JP2003031494A - Optical property measurement mask, optical property measurement method, projection optical system adjustment method, and exposure apparatus manufacturing method - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide an optical characteristic measurement mask that can reduce the measurement time. SOLUTION: A measurement mask R _T has a plurality of patterns 6.
7 _{i, j} are provided, and an opening plate 66 is provided on the emission side of the substrate and has pinhole openings 70 _{i, j} individually corresponding to each pattern. The light transmittance is set to such a degree that the light shielding part partially transmits light. For this reason, when the mask _RT is arranged on the object plane and illuminated by the illumination light, the illumination light emitted from the pattern passes through each of the pinhole openings and the resist on the wafer on the image plane via the projection optical system PL. The pattern is projected onto the layer and the pattern is transferred to the resist layer. At this time, even a small amount of light from the light-shielding portion, which is originally light-shielded, reaches the wafer and promotes exposure of the resist on the wafer surface. Therefore, it is possible to shorten the exposure time for obtaining a pattern transfer image having a target line width, and the measurement time for the optical characteristics of the projection optical system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical characteristic measuring mask, an optical characteristic measuring method, a projection optical system adjusting method, and an exposure apparatus manufacturing method. The optical characteristic measuring mask used for measuring the optical characteristic of the projection optical system projecting onto two surfaces, the optical characteristic measuring method for measuring the optical characteristic of the projection optical system, and the result measured by the optical characteristic measuring method. The present invention relates to an adjusting method for adjusting a projection optical system based on the above, and a manufacturing method for an exposure apparatus that transfers a mask pattern onto a substrate.

[0002]

2. Description of the Related Art Conventionally, semiconductor elements (CPU, DRA
M, etc.), image pickup devices (CCDs, etc.), liquid crystal display devices, thin film magnetic heads, etc. In the lithography process, various exposure apparatuses for forming a device pattern on a substrate are used. In recent years, with high integration of semiconductor elements and the like, a step-and-repeat type reduction projection exposure apparatus (so-called stepper) capable of accurately forming a fine pattern on a substrate such as a wafer or a glass plate with high throughput, A projection exposure apparatus such as a step-and-scan type scanning exposure apparatus (so-called scanning stepper), which is an improved version of this stepper, is mainly used.

By the way, when manufacturing a semiconductor device or the like, it is necessary to stack different layers of circuit patterns on a substrate, and therefore, the reticle (or mask) on which the circuit pattern is drawn and the substrate are formed. It is important to accurately superimpose the pattern already formed on each of the shot areas. In order to perform such superposition with high accuracy, it is necessary to accurately measure the optical characteristics of the projection optical system, adjust it to a desired state, and manage it.

Conventionally, as a method for measuring the optical characteristics of a projection optical system, exposure is performed using a measurement mask on which a predetermined measurement pattern is formed, and the substrate on which the projected image of the measurement pattern is transferred is developed. A method of calculating optical characteristics based on a measurement result obtained by measuring the obtained resist image (hereinafter, referred to as “baking method”) is mainly used. In addition, without actually performing the exposure, the measurement mask is illuminated with illumination light to measure the aerial image (projection image) of the measurement pattern formed by the projection optical system, and the optical characteristics are determined based on the measurement result. Calculation method (hereinafter referred to as "aerial image measurement method")
It is also done).

In the conventional exposure apparatus, low order aberrations such as so-called Seidel's 5 aberrations such as spherical aberration, coma aberration, astigmatism, curvature of field, distortion (distortion), etc. are recorded by the above-mentioned printing method or aerial image measuring method. It has been mainly performed to measure and to adjust and manage the various aberrations of the projection optical system based on the measurement result.

However, semiconductor devices are becoming highly integrated year by year,
Along with this, the exposure apparatus is required to have an exposure performance with higher accuracy, and in recent years, it has become insufficient to adjust only the above-mentioned low-order aberrations. Therefore,
The optical characteristics of the projection optical system including higher order aberrations can be measured by measuring the wavefront aberration of the projection optical system not only during assembly in the exposure equipment manufacturing plant but also after installation in the clean room of the semiconductor manufacturing plant. The need for maintenance has arisen.

As a technique for measuring the wavefront aberration using the above-mentioned printing method, a mask having a special structure is used, and a plurality of measurement patterns on the mask are individually provided with pinholes and projection optics. In addition to printing on the substrate sequentially through the system, the reference pattern on the mask is printed on the substrate via the projection optical system without passing through the condenser lens and pinhole, and multiple measurements are obtained as a result of each printing. U.S. Pat. No. 5,978,085 discloses an invention relating to a technique for calculating a wavefront aberration by measuring a positional deviation amount of each resist image of a work pattern with respect to a resist image of a reference pattern and performing a predetermined calculation.

[0008]

However, when the technique disclosed in the above-mentioned US patent is applied to an actual stepper or the like, there is an inconvenience that it takes too much time for measurement. This is for the following reason.

In the mask described in the above-mentioned US patent, each of the plurality of measurement patterns on the mask is printed on the substrate through the individually provided pinholes and projection optical system in sequence, so that the existence of pinholes causes The energy of the illumination light reaching the substrate is about 1 of the energy applied to the mask.
It is about / 100. Therefore, the illumination energy required for measuring the optical characteristics using the conventional measurement mask is 20 m.
Since it is about J to 30 mJ, it is necessary to simply calculate and use 2 to 3 J or more illumination energy when using the mask described in the above-mentioned US patent, and when the same illumination light source and illumination optical system are used. It takes about 100 times as long as the conventional baking method.

The present invention has been made under such circumstances, and a first object of the present invention is to provide an optical characteristic measuring mask which can shorten the time required for measuring the optical characteristic.

A second object of the present invention is to provide a method for measuring the optical characteristics of a projection optical system which can improve the measuring ability.

A third object of the present invention is to provide a method of adjusting a projection optical system which can adjust the optical characteristics of the projection optical system with high accuracy.

A fourth object of the present invention is to provide a method of manufacturing an exposure apparatus capable of accurately transferring a mask pattern onto a substrate.

[0014]

According to a first aspect of the present invention, there is provided an optical characteristic used for measuring an optical characteristic of a projection optical system (PL) for projecting a pattern on a first surface onto a second surface. The measurement mask includes a plurality of measurement patterns (6
7 _{i, j} ) has a pattern forming member (60) having a pattern surface arranged in a predetermined positional relationship; arranged on the ejection side of the pattern forming member with respect to the pattern surface, and corresponds to each of the measurement patterns. An aperture plate (66) having a plurality of pinhole-shaped apertures (70 _{i, j} ) formed therein, and the light-shielding portion of each of the measurement patterns is set to have a transmittance that allows some light to pass through. Is a mask for measuring optical characteristics.

Here, the optical characteristic measuring mask is not limited to a photomask or an original plate such as a reticle, but includes all those having the above-mentioned respective constituents.

According to this, for example, in a state where the pattern surface of the pattern forming member is located on the first surface, the mask for measuring optical characteristics is arranged on the object plane side of the projection optical system, and the image plane of the projection optical system (first A substrate having a surface coated with a photosensitive agent (resist) is placed on the second surface. In this state, when the plurality of measurement patterns arranged in a predetermined positional relationship on the pattern surface of the pattern forming member are illuminated by the illumination light, the illumination light emitted from each of the measurement patterns emits the illumination light of the pattern forming member. It enters the projection optical system through each of a plurality of pinhole-shaped openings provided corresponding to each measurement pattern on the aperture plate arranged on the exit side with respect to the pattern surface,
It is projected on the photosensitive layer (resist layer) on the substrate through the projection optical system. At this time, since the light-shielding portion of each measurement pattern is set to have such a transmittance that a part of light is transmitted, a slight amount of light (hereinafter, appropriately referred to as “leakage light”) from a portion where light is originally shielded. ) Also reaches on the substrate through each pinhole-shaped opening and the projection optical system, and promotes the exposure of the photosensitive agent on the substrate surface. That is, the leaked light promotes the exposure of the entire area on which the measurement pattern is projected. Therefore, it is possible to shorten the irradiation time (exposure time) of the illumination light for obtaining the transfer image of the target line width measurement pattern, for example, the resist image, and as a result, it is possible to measure the optical characteristics of the projection optical system. It is possible to reduce the time required.

In place of the substrate having the photosensitive layer formed on the surface thereof, for example, a reference plate having at least one reference pattern formed thereon is arranged on the second surface (image surface) of the projection optical system or a conjugate surface thereof. The optical characteristics of the projection optical system may be measured based on the amount of displacement between the projected image of each measurement pattern and the reference pattern.

In this case, as in the optical characteristic measuring mask according to claim 2, a plurality of light-collecting elements (corresponding to each of the plurality of measuring patterns on the incident side of the pattern forming member). 65 _{i, j} ) may be further provided.

In each of the optical characteristic measuring masks described in claims 1 and 2, like the optical characteristic measuring mask described in claim 3, the pattern forming member has a position of a projection position of each measuring pattern. It is possible to further have a reference pattern (74 ₁ , 74 ₂ ) that serves as a reference for the shift.

In this case, as in the optical characteristic measuring mask according to the fourth aspect, the reference pattern can be set to have such a transmittance that the light-shielding portion partially transmits light. .

According to a fifth aspect of the present invention, there is provided an optical characteristic measuring method for measuring an optical characteristic of a projection optical system for projecting a pattern on a first surface onto a second surface. While arranging multiple measurement patterns according to the positional relationship of
A reference substrate (W _F ) on which a plurality of reference patterns are formed in advance in a positional relationship corresponding to the positional relationship of the plurality of measurement patterns is arranged on the second surface, and the plurality of measurement patterns are irradiated with illumination light. Each of the illumination light that illuminates and is generated from each of the plurality of measurement patterns is on the second surface via a pinhole and the projection optical system that are individually provided for each of the measurement patterns. Forming step of projecting onto the reference substrate to form transfer images of the respective measurement patterns on the photosensitive layer on the reference substrate; from corresponding reference patterns of transfer images of the respective measurement patterns on the reference substrate And a measuring step of obtaining an optical characteristic of the projection optical system based on the positional deviation amount of.

According to this, in the forming step, a plurality of measurement patterns are arranged on the first surface (the object plane of the projection optical system) in a predetermined positional relationship, and a plurality of reference patterns are previously formed on the second surface. Arranges the reference substrate formed in a positional relationship corresponding to the positional relationship of the plurality of measurement patterns. Then, in this state, the plurality of measurement patterns are illuminated with illumination light, and each of the illumination light generated from each of the plurality of measurement patterns is provided with a pinhole corresponding to each measurement pattern. And projecting onto the reference substrate on the second surface (image plane of the projection optical system) via the projection optical system,
A transfer image of each measurement pattern is formed on the photosensitive layer on the reference substrate. Next, in the measurement step, the optical characteristics of the projection optical system are obtained based on the amount of positional deviation of the transfer image of each measurement pattern on the reference substrate from the corresponding reference pattern.

That is, in the optical characteristic measuring method of the present invention, since it is sufficient to transfer the measurement pattern, the transfer of the reference pattern (normally this transfer is performed by the step-and-repeat method) becomes unnecessary. Therefore, the time required for the exposure can be shortened accordingly.

The illumination light (diffracted light) generated from each of the measurement patterns is limited by a pinhole-shaped opening provided corresponding to each measurement pattern, and passes through each opening. Only light reaches the substrate. The light passing through each of the openings has different positions passing through the pupil plane of the projection optical system, depending on which position of the measurement pattern the light originates from. That is, the image of each measurement pattern is formed at a position displaced according to the inclination of the wavefront of light passing through each measurement pattern with respect to the ideal wavefront. On the other hand, since the reference substrate can be manufactured in advance, by using a highly accurate pattern drawing device,
The arrangement of the reference pattern can be made almost as designed. Therefore, the amount of positional deviation of the transfer image of each measurement pattern on the reference substrate from the corresponding reference pattern is an amount that accurately reflects the optical characteristics of the projection optical system. It is possible to accurately obtain the optical characteristics of. Therefore, in terms of time and accuracy, it is possible to contribute to the improvement of the measurement ability of the optical characteristics of the projection optical system.

The invention according to claim 6 is the invention according to claim 1 or 2.
An optical characteristic measuring method for measuring the optical characteristic of a projection optical system using the optical characteristic measuring mask according to claim 1, illuminating the optical characteristic measuring mask arranged on the first surface with illumination light, Photosensitivity on a substrate (W) arranged on the second surface via a pinhole-shaped opening provided corresponding to each of the plurality of measurement patterns and the projection optical system. A transfer step of transferring to the layer; a measurement step of obtaining the optical characteristics of the projection optical system based on the amount of displacement of the transfer image of each measurement pattern from a predetermined reference position; .

According to this, in the transfer step, each mask for optical characteristic measurement according to claim 1 and 2 arranged on the first surface is illuminated with illumination light, and a pattern is formed on the mask for optical characteristic measurement. A plurality of measurement patterns formed on a member and a photosensitive layer on a substrate disposed on the second surface through a pinhole-shaped opening provided corresponding to each measurement pattern and a projection optical system. Transfer to. At this time, since the light-shielding portion of each measurement pattern is set to have a transmittance that allows a part of light to pass therethrough, leakage light from the portion where the light is originally shielded also has a pinhole-shaped opening and a projection optical system. Reach the substrate through the substrate and accelerate the exposure of the photosensitive layer on the substrate surface. That is,
The leaked light promotes the exposure of the entire area on which the measurement pattern is projected. Therefore, it is possible to shorten the irradiation time (exposure time) of the illumination light for obtaining the transfer image of the target line width measurement pattern, for example, the resist image.

Then, in the measuring step, the optical characteristics of the projection optical system are obtained based on the amount of displacement of the transfer image of each measuring pattern from the predetermined reference position. Also in this case, claim 5
For the same reason as above, the image of each measurement pattern is imaged at a position displaced in accordance with the inclination of the wavefront of the light passing through each measurement pattern with respect to the ideal wavefront. The quantity accurately reflects the optical characteristics of the projection optical system, and based on this quantity, the optical characteristics of the projection optical system can be accurately obtained. Therefore, in terms of time and accuracy, it is possible to contribute to the improvement of the measurement ability of the optical characteristics of the projection optical system.

In this case, as in the optical characteristic measuring method according to the seventh aspect, in the transferring step, a plurality of reference patterns are previously formed on the substrate in a positional relationship corresponding to a positional relationship of the plurality of measuring patterns. Using the formed reference substrate, in the measurement step, the optical characteristic of the projection optical system can be obtained based on the amount of positional deviation of the transfer image of each measurement pattern from the corresponding reference pattern.

In the optical characteristic measuring method according to the fifth or seventh aspect, the positional relationship (interval, etc.) of the plurality of reference patterns on the reference substrate is measured, and the measurement result is used for measurement. It is desirable to obtain the amount of positional deviation described above for each pattern or to correct the measurement result of the optical characteristics of the projection optical system. As a result, the measurement error of the optical characteristics of the projection optical system due to the position error of the reference pattern on the reference substrate can be reduced.

The invention according to claim 8 is the invention according to claim 3 or 4.
An optical characteristic measuring method for measuring the optical characteristic of a projection optical system using the optical characteristic measuring mask according to claim 1, illuminating the optical characteristic measuring mask arranged on the first surface with illumination light, Transferring the plurality of measurement patterns to a photosensitive layer on a substrate arranged on the second surface via a pinhole-shaped opening provided corresponding to each of the measurement patterns and the projection optical system. A second transfer step in which the reference pattern on the optical characteristic measuring mask is sequentially transferred to the photosensitive layer on the substrate by using the illumination light as a reference for positional deviation of each measuring pattern. An optical characteristic measuring method including: a measuring step for obtaining an optical characteristic of the projection optical system based on a positional deviation amount of a transfer image of each measuring pattern from a corresponding reference pattern.

According to this, in the first transfer step, each of the optical characteristic measuring masks according to claim 3 and 4 arranged on the first surface is illuminated with illumination light, and the optical characteristic measuring masks are illuminated. A plurality of measurement patterns formed on the pattern forming member are arranged on the second surface via a pinhole-shaped opening provided corresponding to each of the measurement patterns and a projection optical system. Transfer to the photosensitive layer. At this time, since the light-shielding portion of each measurement pattern is set to have a transmittance that allows a part of light to pass therethrough, leakage light from the portion where the light is originally shielded also has a pinhole-shaped opening and a projection optical system. Reach the substrate through the substrate and accelerate the exposure of the photosensitive layer on the substrate surface. That is, the leaked light promotes the exposure of the entire area on which the measurement pattern is projected. Therefore, it is possible to shorten the irradiation time (exposure time) of the illumination light for obtaining the transfer image of the target line width measurement pattern, for example, the resist image.

In the second transfer step, the reference pattern on the optical characteristic measuring mask is sequentially transferred to the photosensitive layer on the substrate using the illumination light as a reference for the positional deviation of each measuring pattern.

Then, in the measuring step, the optical characteristic of the projection optical system is obtained based on the amount of displacement of the transfer image of each measuring pattern from the corresponding reference pattern. Also in this case, for the same reason as in claim 5, the image of each measurement pattern is
An image is formed at a position shifted according to the inclination of the wavefront of light passing through each measurement pattern with respect to the ideal wavefront. on the other hand,
The diffracted light generated from the reference pattern is directly incident on the projection optical system without being restricted by the pinhole-shaped opening, and is projected onto the substrate via the projection optical system. Therefore, by irradiating the illumination light in a state where the reference pattern is positioned near the optical axis of the projection optical system, the image is imaged in a state in which there is almost no influence of the aberration of the projection optical system and there is no positional deviation. . Therefore, the amount of positional deviation described above is an amount that accurately reflects the optical characteristics of the projection optical system, and based on this amount, the optical characteristics of the projection optical system can be accurately obtained. Therefore, in terms of time and accuracy, it is possible to contribute to the improvement of the measurement ability of the optical characteristics of the projection optical system.

In each of the optical characteristic measuring methods described in claims 5 to 8, as in the invention described in claim 9, in the measuring step, the wavefront of the projection optical system is calculated based on the calculation result of the positional deviation amount. Aberration can be calculated.

The invention described in claim 10 is an optical characteristic measuring method for measuring an optical characteristic of a projection optical system for projecting a pattern on a first surface onto a second surface, wherein a predetermined measurement pattern is formed. And a step of preparing a plurality of measuring masks in which the light shielding portions of the measuring pattern have different transmittances; a step of measuring the thickness of the photosensitive layer on the substrate for transferring the measuring pattern; Selecting a specific measurement mask from the plurality of measurement masks according to the measured thickness of the photosensitive layer; and illuminating the specific measurement mask by arranging the specific measurement mask on the first surface. Illuminating with light and transferring the measurement pattern on the specific measurement mask to the photosensitive layer on the substrate arranged on the second surface via the projection optical system; Based on the measurement result of the transfer image of the measurement pattern An optical characteristic measuring method comprising: step and of calculating the optical characteristic of the projection optical system are.

According to this, the thickness of the photosensitive layer on the substrate is measured before the measurement of the optical characteristics is started, and the illumination light transmission according to the measured thickness (and its sensitivity) of the photosensitive layer is performed. A specific measurement mask for which the light-shielding portion has been set is selected.
Then, the selected specific measurement mask is arranged on the first surface and illuminated with illumination light, and the measurement pattern on the specific measurement mask is arranged on the second surface via the projection optical system. The image is transferred onto the photosensitive layer on the substrate, and the optical characteristics of the projection optical system are calculated based on the measurement result of the transfer image of the measurement pattern on the substrate. This makes it possible to keep the line width of the transfer image of the measurement pattern formed on the substrate within the range of the desired line width, and as a result, the projection optical system is not affected by the thickness of the photosensitive layer. The optical characteristics of the system can be accurately measured. Therefore, in terms of accuracy, it is possible to contribute to the improvement of the measurement capability of the optical characteristics of the projection optical system.

An eleventh aspect of the present invention is an optical characteristic measuring method for measuring the optical characteristic of a projection optical system using the optical characteristic measuring mask according to the first or second aspect. While illuminating the mask for measuring optical characteristics arranged in, the plurality of measurement patterns are projected through the pinhole-shaped opening and the projection optical system, respectively, and the second surface or the conjugate surface thereof is projected. Based on the amount of displacement from the predetermined reference position of the projected image of each measurement pattern,
An optical characteristic measuring method is characterized in that the optical characteristic of the projection optical system is measured.

According to this, the optical characteristic measuring mask arranged on the first surface is illuminated, and a plurality of measuring patterns are projected through the pinhole-shaped opening and the projection optical system, respectively. The optical characteristic of the projection optical system is measured based on the amount of displacement of the projected image of each measurement pattern on the surface or its conjugate surface from a predetermined reference position. in this case,
Since the light-shielding portion of each measurement pattern is set to a transmittance that allows some light to pass through, leakage light from the portion where light is originally shielded is also transmitted through each pinhole-shaped opening and projection optical system. Reach onto the substrate. In this case as well, for the same reason as in claim 5, the image of each measurement pattern is formed at a position displaced according to the inclination of the wavefront of the light passing through each measurement pattern with respect to the ideal wavefront. The above positional deviation amount is an amount that accurately reflects the optical characteristics of the projection optical system,
Based on this amount, the optical characteristics of the projection optical system can be accurately obtained. Therefore, in terms of accuracy, it is possible to contribute to the improvement of the measurement capability of the optical characteristics of the projection optical system.

In this case, as in the optical characteristic measuring method according to the twelfth aspect, a reference plate on which at least one reference pattern is formed is arranged on the second surface or a conjugate surface thereof, and each of the reference patterns is formed. It is possible to obtain the positional deviation amount of the projected image of the measurement pattern.

The invention described in claim 13 is the invention according to claims 5 to 1.
Measuring the optical characteristic of the projection optical system by using the optical characteristic measuring method according to any one of 2); and adjusting the projection optical system based on the measurement result of the optical characteristic.
It is a method of adjusting the projection optical system including.

According to this, since the optical characteristics of the projection optical system are measured by using the optical characteristic measuring methods described in claims 5 to 12, the optical characteristics of the projection optical system can be accurately measured. Since the projection optical system is adjusted based on the measurement result of the optical characteristics measured with high accuracy, the optical characteristics of the projection optical system can be adjusted with high accuracy.

The invention according to claim 14 is the mask (R)
13. An exposure apparatus manufacturing method for manufacturing an exposure apparatus (10) for transferring the pattern according to claim 1 onto a substrate (W) via a projection optical system, the optical characteristic measurement according to claim 5. And a step of adjusting the projection optical system based on the measured optical characteristic, and a method of measuring the optical characteristic of the projection optical system using a method.

According to this method, the optical characteristics of the projection optical system are accurately measured by using the optical characteristic measuring methods according to claims 5 to 12, and the projection optical system is adjusted based on the measured optical characteristics. Therefore, the imaging characteristics of the projection optical system can be adjusted accurately. Therefore, an exposure apparatus is manufactured in which the imaging characteristics of the projection optical system are adjusted with high accuracy, and the pattern of the mask is accurately transferred onto the substrate through the projection optical system by performing exposure using the exposure apparatus. It will be possible.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION << First Embodiment >> A first embodiment of the present invention will be described below with reference to FIGS. 1 to 7B.

FIG. 1 shows the schematic arrangement of an exposure apparatus 10 according to the first embodiment. This exposure apparatus 10 is
This is a step-and-repeat reduction projection exposure apparatus using a pulse laser light source as an exposure light source (hereinafter referred to as “light source”), that is, a so-called stepper.

This exposure apparatus 10 serves as a mask stage for holding an illumination system including a light source 16 and an illumination optical system 12, and a reticle R as a mask illuminated by exposure illumination light EL as an energy beam from the illumination system. Reticle stage RST, a projection optical system PL for projecting the exposure illumination light EL emitted from the reticle R onto a wafer W (on the image plane) as a substrate, and a substrate on which a Z tilt stage 58 for holding the wafer W is mounted. A wafer stage WST as a stage and a control system for these are provided.

As the light source 16, here, ArF is used.
An excimer laser light source (output wavelength 193 nm) is used. As the light source 16, a light source that outputs pulsed light in the vacuum ultraviolet region such as an F ₂ laser light source (output wavelength 157 nm) or a KrF excimer laser light source (output wavelength 248 n
A light source that outputs pulsed light in the near-ultraviolet region such as m) may be used.

The light source 16 is actually the illumination optical system 1.
2 is installed in a low-clean service room different from the clean room in which the chamber 11 in which the exposure apparatus main body including the reticle stage RST, the projection optical system PL, the wafer stage WST and the like is housed is installed. And is connected to the chamber 11 via a light-transmitting optical system (not shown) including an optical axis adjusting optical system at least partially called a beam matching unit. This light source 16
Is based on the control information TS from the main controller 50, the internal controller turns on / off the output of the laser beam LB.
Off, energy per pulse of the laser beam LB, oscillation frequency (repetition frequency), center wavelength, spectrum half width, etc. are controlled.

The illumination optical system 12 includes a cylinder lens,
Beam expander, zoom optical system (neither shown), and optical integrator (homogenizer)
Beam shaping / illuminance homogenizing optical system 20 including a fly-eye lens or an internal reflection type integrator (fly-eye lens in the present embodiment) 22 and the like, and an illumination system aperture stop plate 2
4, first relay lens 28A, second relay lens 28
B, a reticle blind 30, a mirror M for bending the optical path, a condenser lens 32, and the like.

Beam shaping / illuminance uniforming optical system 20
Are connected to a light transmission optical system (not shown) through a light transmission window 17 provided in the chamber 11. This beam shaping
The illuminance homogenizing optical system 20 shapes the cross-sectional shape of the laser beam LB which is pulse-emitted by the light source 16 and is incident through the light transmission window 17 using, for example, a cylinder lens or a beam expander. Then, the fly-eye lens 22 positioned on the exit end side inside the beam shaping / illuminance uniformizing optical system 20.
In order to illuminate the reticle R with a uniform illuminance distribution, by the incidence of the laser beam whose cross-sectional shape is shaped, on the exit-side focal plane of the illumination optical system 12, which is arranged so as to substantially coincide with the pupil plane. A surface light source (secondary light source) including a large number of point light sources (light source images) is formed. The laser beam emitted from this secondary light source is hereinafter referred to as "illumination light EL".

An illumination system aperture stop plate 24 made of a disk-shaped member is arranged near the exit-side focal plane of the fly-eye lens 22. The illumination system aperture stop plate 24 has, for example, an aperture stop having a normal circular aperture (normal aperture) and an aperture stop having a small circular aperture (small aperture) for reducing a coherence factor σ value at substantially equal angular intervals. σ stop), a ring-shaped aperture stop for ring-shaped illumination (ring-shaped aperture stop), and a modified aperture stop formed by eccentrically arranging a plurality of apertures for the modified light source method (of which two types are shown in FIG. 1). Only the aperture stop is shown) and so on. The illumination system aperture stop plate 24 is adapted to be rotated by a drive device 40 such as a motor controlled by the main control device 50, whereby any aperture stop is selectively placed on the optical path of the illumination light EL. The light source surface shape in the Koehler illumination, which will be described later, is limited to an annular zone, a small circle, a large circle, a fourth circle, or the like.

In this embodiment, the aperture stop plate 24 is used to change the light quantity distribution of illumination light on the pupil plane of the illumination optical system (the shape and size of the secondary light source), that is, the illumination condition of the reticle R. However, instead of the aperture stop plate 24 or in combination with the aperture stop plate 24, for example, a plurality of diffractive optical elements arranged interchangeably on the optical path of the illumination optical system, and movable along the optical axis of the illumination optical system. An optical unit including at least one prism (conical prism, polyhedron prism, etc.) and at least one zoom optical system is provided as a light source 16 and an optical integrator (fly-eye lens) 22.
And the intensity distribution of the illumination light on the incident surface of the optical integrator (fly-eye lens) 22 or the incident angle range of the illumination light is made variable to reduce the light amount loss due to the change of the illumination condition. It is preferable to minimize it.

Illumination light EL emitted from the illumination system aperture stop plate 24
The reticle blind 30 on the optical path of the first
A relay optical system including a relay lens 28A and a second relay lens 28B is arranged. The reticle blind 30 is arranged on a conjugate plane with respect to the pattern surface of the reticle R, and has a rectangular opening that defines a rectangular illumination area IAR on the reticle R. Here, as the reticle blind 30, a movable blind whose opening shape is variable is used, and the opening is set by the main control device 50 based on blind setting information also called masking information.

A bending mirror M for reflecting the illumination light EL passing through the second relay lens 28B toward the reticle R is arranged on the optical path of the illumination light EL behind the second relay lens 28B constituting the relay optical system. And this mirror M
The condenser lens 32 is arranged on the optical path of the rear illumination light EL.

In the above configuration, the fly-eye lens 2
The incident surface of No. 2, the arrangement surface of the reticle blind 30, and the pattern surface of the reticle R are optically set to be conjugate with each other, and are formed on the exit-side focal plane of the fly-eye lens 22 (the pupil of the illumination optical system). Surface) and the Fourier transform surface (exit pupil surface) of the projection optical system PL are optically set to be conjugate with each other to form a Koehler illumination system.

The illumination optical system 12 configured in this way
In brief, the laser beam LB pulse-emitted from the light source 16 is incident on the beam shaping / illuminance uniforming optical system and the cross-sectional shape is shaped, and then is incident on the fly-eye lens 22. As a result, the fly-eye lens 22
The secondary light source described above is formed at the exit end of the.

Illumination light EL emitted from the above-mentioned secondary light source
Passes through one of the aperture stops on the illumination system aperture stop plate 24, then passes through the first relay lens 28A, the rectangular aperture of the reticle blind 30, and then passes through the second relay lens 28B. After the optical path is bent vertically downward, the rectangular illumination area IAR on the reticle R held on the reticle stage RST is illuminated with a uniform illuminance distribution via the condenser lens 32.

The reticle R is loaded on the reticle stage RST, and is held by suction via an electrostatic chuck (or vacuum chuck) or the like (not shown). The reticle stage RST is driven by a drive system (not shown) on a horizontal plane (XY
It is configured such that minute driving (including rotation) is possible within a plane. Further, reticle stage RST is configured to be movable within a predetermined stroke range (about the length of reticle R) in the Y-axis direction. The position of reticle stage RST is measured with a predetermined resolution (for example, a resolution of about 0.5 to 1 nm) by a position detector (not shown), for example, a reticle laser interferometer, and the measurement result is sent to main controller 50. It is being supplied.

As the projection optical system PL, for example, a bilateral telecentric reduction system is used. The projection magnification of this projection optical system PL is, for example, 1/4, 1/5 or 1/6.
Etc. Therefore, as described above, when the illumination area IAR on the reticle R is illuminated by the illumination light EL, the image formed by reducing the pattern formed on the reticle R by the projection optical system PL at the projection magnification is the surface. A rectangular exposure area IA on the wafer W coated with a resist (photosensitizer)
It is projected and transferred (usually coincident with the shot area).

As the projection optical system PL, as shown in FIG. 1, a refraction system consisting of a plurality of, for example, 10 to 20 refracting optical elements (lenses) 13 is used. A plurality of lenses 13 forming this projection optical system PL
Among them, a plurality of lenses 13 on the object plane side (reticle R side) (here, four lenses for simplification of description)
₁ , 13, ₂ , 13 ₃ , and 13 ₄ are movable lenses that can be externally driven by the imaging characteristic correction controller 48. The lenses 13 ₁ , 13 ₂ and 13 ₄ are respectively held by lens holders (not shown), and these lens holders are supported at three points in the direction of gravity by drive elements (not shown) such as piezo elements. Then, by independently adjusting the voltage applied to these drive elements, the lens 1
3 ₁ , 13 ₂ , 13 ₄ are shift-driven in the Z-axis direction which is the optical axis direction of the projection optical system PL, and are driven in the tilt direction with respect to the XY plane (that is, the rotation direction around the X-axis and the rotation direction around the Y-axis). It is possible (tiltable). Further, the lens 13 ₃ is held by a lens holder (not shown) are driven element disposed such as a piezoelectric element at approximately 90 ° intervals, for example, in the outer peripheral portion of the lens holder, the two driving elements facing each other By adjusting the voltage applied to each drive element as a set, the lens 1
3 ₃ can be two-dimensionally shift-driven in the XY plane.

The reticle R and the optical elements (particularly lens elements) of the projection optical system PL are respectively illuminated by the illumination light E.
The glass material is appropriately selected according to the wavelength of L. For example,
When the wavelength of the illumination light EL is about 190 nm or more (the illumination light EL is ArF excimer laser light, KrF excimer laser light, or the like), synthetic quartz can be used. However, for example, when the wavelength of the illumination light EL is about 180 nm or less (the illumination light EL is F ₂ laser light or the like), it is difficult to use synthetic quartz in terms of transmittance and the like, so that fluoride crystals such as fluorite and impurities ( Synthetic quartz or the like doped with fluorine etc. is used.

The wafer stage WST can be freely driven in the XY two-dimensional plane by the wafer stage drive section 56. The wafer W is electrostatically attracted (or vacuum attracted) on the Z tilt stage 58 mounted on the wafer stage WST via a wafer holder (not shown).
And so on. The Z tilt stage 58 has the function of adjusting the position (focus position) of the wafer W in the Z direction and adjusting the tilt angle of the wafer W with respect to the XY plane. The X, Y position and rotation (including yawing, pitching, and rolling) of wafer stage WST are fixed to movable mirror 5 fixed on Z tilt stage 58.
An external wafer laser interferometer 54W measures through 2W, and the measured value of the wafer laser interferometer 54W is supplied to the main controller 50.

On the Z-tilt stage 58, a reference mark plate FM having a first reference mark and other reference marks for so-called baseline measurement of a wafer alignment system (not shown) is formed on the surface of the wafer W. It is fixed so that it is flush with the surface of.

The control system is mainly constituted by the main controller 50 in FIG. The main controller 50 is composed of a so-called workstation (or microcomputer) including a CPU (central processing unit), a ROM (read only memory), a RAM (random access memory), etc. For example, the stepping between shots of the wafer stage WST, the exposure timing, etc. are centrally controlled so as to be performed accurately.

Next, the measurement reticle R _T as an optical characteristic measurement mask used when measuring the optical characteristics of the projection optical system PL of the exposure apparatus 10 of this embodiment will be described.

FIG. 2 shows this measurement reticle R._TOutline of
A perspective view is shown. Moreover, in FIG.
Reticle R loaded on the RST_TLight of
The schematic diagram of the XZ cross section near the axis AX is a model of the projection optical system PL.
It is shown with a schematic diagram. Further, in FIG. 4, the reticle is
Reticle R loaded on the stage RST _T
Is a schematic view of the XZ cross section near the −Y side end of the projection optical system P.
It is shown with a schematic diagram of L.

As is apparent from FIG. 2, the entire shape of the measurement reticle R _T is substantially the same as that of a normal reticle with a pellicle. This measurement reticle R _T
Is a glass substrate 60 as a pattern forming member, and a lens mounting member 6 having a rectangular plate shape fixed to the central portion of the upper surface of the glass substrate 60 in FIG. 2 in the X-axis direction.
2. A spacer member 64 made of a frame-shaped member attached to the lower surface of the glass substrate 60 in FIG. 2 and having the same appearance as a normal pellicle frame, and the spacer member 6
4 is provided with an opening plate 66 and the like attached to the lower surface.

In the lens mounting member 62, n circular openings 63 _{i, j} (i = 1 to p, i = 1 to p, i = 1 to p
j = 1 to q, pxq = n) are formed. Inside each circular opening 63 _{i, j,} a condenser lens 65 _{i, j} made of a convex lens having an optical axis in the Z-axis direction is provided (see FIG. 3).

Further, the glass substrate 60 and the spacer member 64
As shown in FIG. 3, reinforcing members 69 are provided at predetermined intervals inside the space surrounded by the opening plate 66.

Further, as shown in FIG. 3, measurement patterns 67 _{i, j} are formed on the lower surface of the glass substrate 60 so as to face the condenser lenses 65 _{i, j} . Further, as shown in FIG. 4, the opening plate 66 is formed with pinhole-shaped openings 70 _{i, j} facing the respective measurement patterns 67 _{i, j} . The pinhole-shaped opening 70 _{i, j} has a diameter of, for example, about 100 to 150 μm.

Returning to FIG. 2, the lens holding member 62 has a Y
The opening 7 is formed in the center of a part of the belt-shaped region at both ends in the axial direction.
2 ₁ and 72 ₂ are formed respectively. As shown in FIG. 4, a reference pattern 74 ₁ is formed on the lower surface (pattern surface) of the glass substrate 60 so as to face one opening 72 ₁ . Although not shown, the other opening 7
The lower surface of the glass substrate 60 (pattern surface) facing 2 ₂
In addition, a reference pattern similar to the reference pattern 74 ₁ (for convenience, described as “reference pattern 74 ₂ ”) is formed.

Further, as shown in FIG. 2, on the X axis passing through the center of the reticle of the glass substrate 60, a pair of reticle alignment marks RM1 are arranged on both outsides of the lens holding member 62 in a symmetrical arrangement with respect to the center of the reticle. RM2 is formed.

Here, in this embodiment, as the measurement pattern 67 _{i, j} , a mesh pattern (street line pattern) as shown in FIG. 5A is used.
The measurement pattern 67 _{i, j} is a negative pattern (so-called blank pattern) formed by removing the chromium layer, which is the light-shielding portion, in a mesh shape (street line shape) by patterning. Here, the thickness of the chrome layer is, for example, 0.
It is about 1 μm, and has a transmittance of about 2 to 20% with respect to the illumination light EL (ArF excimer laser light).

Optimal conditions (such as the transmittance of the light-shielding portion) depending on the illumination conditions of the reticle R (the light amount distribution of the illumination light EL on the pupil plane of the illumination optical system), the type of resist, and the film thickness.
Therefore, it is possible to prepare a plurality of reticles having different transmittances of the light-shielding portion and select one reticle according to the illumination condition, the type of resist, the film thickness, and the like.

The above measurement pattern 67_{i, j}Corresponding to
The reference pattern 74₁, 74₂As shown in Fig. 5 (B)
Measurement pattern 67_{i, j}At the same pitch as
Uses a two-dimensional grid pattern with square patterns
I have been. In this case, the reference pattern 74₁, 74₂When
The pattern of the light-shielding chrome layer is a two-dimensional grid.
Negative pattern formed by removing by negative (
A loose pattern) is used. Also in this case,
The thickness of the chrome layer is the same as the measurement pattern 67 described above. _{i, j}When
With the same thickness, illumination light EL (ArF excimer laser
(Light) has a similar transmittance.

The pattern of FIG. 5A is used as the reference patterns 74 ₁ and 74 ₂ and the pattern of FIG.
It is possible to use the pattern shown in (B).
Further, the measurement pattern 67 _{i, j} is not limited to this, and patterns of other shapes may be used. In that case,
As the reference pattern, a pattern having a predetermined positional relationship with the measurement pattern may be used. That is,
The reference pattern may be any pattern as long as it serves as a reference for the positional deviation of the measurement pattern, and its shape and the like are not limited, but in order to measure the optical characteristics (including the imaging characteristics) of the projection optical system PL, A pattern in which the pattern is distributed over the entire image field or exposure area of the optical system PL is desirable.

Next, the procedure for measuring the optical characteristics of the projection optical system PL using the measurement reticle R _T will be described.

First, main controller 50 loads measurement reticle R _T onto reticle stage RST via a reticle loader (not shown). Next, in main controller 50, while monitoring the output of laser interferometer 54W, wafer stage WST is moved via wafer stage drive unit 56, and a pair of reticle alignment reference marks (hereinafter, referred to as reference marks for reticle alignment on fiducial mark plate FM. A "second reference mark") is positioned at a predetermined reference position. Here, the reference position is, for example, the center of the pair of second reference marks,
It is set at a position corresponding to the origin on the stage coordinate system defined by the laser interferometer 54W.

Next, in main controller 50, a pair of reticle alignment marks RM1, on reticle R _T for measurement is used.
The RM2 and the second reference marks corresponding thereto are simultaneously observed by a pair of reticle alignment microscopes (not shown), and projected images of the reticle alignment marks RM1 and RM2 on the reference plate FM and the corresponding second reference marks. The reticle stage RST is finely driven in the XY two-dimensional plane via a drive system (not shown) so that the positional deviation amounts of are both minimized. As a result, the reticle alignment is completed and the center of the reticle substantially coincides with the optical axis of the projection optical system PL.

Next, main controller 50 loads wafer W having a surface coated with a resist (photosensitive agent) onto Z tilt stage 58 by using a wafer loader (not shown).

Next, the main controller 50 includes all of the condenser lenses 65 _{i, j} of the measurement reticle R _T and does not include the openings 72 ₁ and 72 ₂ , and the lens holding member 62 in the X-axis direction. In order to form a rectangular illumination area having a length within the maximum width in the X-axis direction, the opening of the reticle blind 30 is set via a drive system (not shown). At the same time,
The main controller 50 rotates the illumination system aperture stop plate 24 via the drive device 40 to set a predetermined aperture stop, for example, a small σ stop on the optical path of the illumination light EL. At this time, the luminous flux diameter (or incident angle range) of the illumination light incident on the optical integrator (fly-eye lens 22) is reduced by using an optical unit (not shown) in the illumination optical system described above, for example, a zoom optical system. It is desirable to minimize light loss.

After such preparatory work, main controller 50
Then, the control information TS is given to the light source 16, the laser beam LB is emitted, and the reticle R _T is irradiated with the illumination light EL to perform exposure. As a result, as shown in FIG. 3, the respective measurement patterns 67 _{i, j} are simultaneously exposed to the wafer W via the corresponding pinhole-shaped openings 70 _{i, j} and the projection optical system PL.
Transferred to the upper resist (positive resist) layer. As a result, a reduced image (latent image) 6 of each measurement pattern 67 _{i, j} as shown in FIG. 6A is formed on the resist layer on the wafer W.
7 ′ _{i, j} are formed at predetermined intervals along the XY two-dimensional direction at predetermined intervals.

Here, in the case of the present embodiment _{, since} the light shielding portion of each measurement pattern 67 _{i, j} has a transmittance of about 2 to 20%, when the transmittance of the light shielding portion is 0. Compared with the above, it is possible to shorten the time until the required amount of energy corresponding to the resist sensitivity is applied to the resist layer.
The reason for this will be briefly described.

FIG. 7A shows a lateral distribution of the light intensity immediately below the pattern surface, focusing on one line pattern portion forming an arbitrary measurement pattern on the measurement reticle R _T of this embodiment. The axis is shown as position. on the other hand,
As a comparative example, FIG. 7B shows the distribution of the light intensity corresponding to FIG. 7A when the transmittance of the light shielding portion is 0, with the horizontal axis representing the position. As is clear from a comparison of these figures, only the shaded portion in FIG. 7 (A) makes this embodiment enter the projection optical system PL via a pinhole-shaped opening, and on the wafer W. It can be seen that a large amount of light is incident on the image forming position of the line pattern on the resist layer. Therefore, in the case of the present embodiment, the exposure time required to transfer the measurement pattern 67 _{i, j} can be shortened by an amount corresponding to the transmittance of the light shielding portion. However, the light transmitted through the light-shielding portion is also radiated to the region on the wafer W corresponding to the light-shielding portion, which means that the contrast of the transfer image of the measurement pattern composed of the above-mentioned line pattern depends on the transmittance of the light-shielding portion. It means to decrease. Therefore, the transmittance of the light shielding portion should not be set too high.

Next, in main controller 50, based on the measured value of a reticle laser interferometer (not shown) and the designed positional relationship between the reticle center and one of the reference patterns 74 ₁ ,
The reticle stage RS is arranged via a drive system (not shown) so that the center position of the reference pattern 74 ₁ coincides with the optical axis AX.
The T is moved in the Y-axis direction by a predetermined distance. Next, in the main controller 50, the illumination light EL is illuminated only on a rectangular area of a predetermined area (this area is not covered by any condenser lens) on the lens holding member 62 including the moved opening 72 _1. In order to define the area, the opening of the reticle blind 30 is set via a drive system (not shown).

Next, the main controller 50, the wafer W latent image 67 _'1,1 of the first measurement pattern 67 _1,1 are formed
The wafer stage WST is moved while monitoring the measurement value of the laser interferometer 54W so that the approximate center of the upper region substantially coincides with the optical axis of the projection optical system PL.

Then, in the main controller 50, the control information T
S is given to the light source 16 to cause the laser beam LB to emit light, and the illumination light EL is irradiated to the reticle _RT to perform exposure.
As a result, the reference pattern 74 ₁ is transferred in an overlapping manner onto the region (referred to as the region S _1,1 ) in which the latent image of the measurement pattern 67 _1,1 of the resist layer on the wafer W is already formed. As a result, in the area S _1,1 on the wafer W, as shown in FIG. 6B, the latent image 67 ′ _1,1 of the measurement pattern 67 _{1,1 and} the latent image 74 of the reference pattern 74 ₁ are formed. ' ₁ is formed in the positional relationship shown in the same figure. In this case, for the same reason as in the case of transfer of the measurement pattern described above, by the amount corresponding to the reference pattern 74 ₁ of the light shielding portion of the transmission required to transfer the reference pattern 74 ₁ can be shortened exposure time .

Next, in the main controller 50, the reticle R
The design arrangement pitch p of the measurement patterns 67 _{i, j} on the wafer W is calculated based on the arrangement pitch of the measurement patterns 67 _{i, j} on _T and the projection magnification of the projection optical system PL, and the pitch is calculated. The wafer stage WST is moved in the X-axis direction by p, and the center of the area (called area S _1,2 ) on the wafer W where the latent image of the second measurement pattern 67 _1,2 is formed. Moves wafer stage WST so that it substantially coincides with the optical axis of projection optical system PL.

Then, in the main controller 50, the control information T
S is given to the light source 16 to cause the laser beam LB to emit light, and the illumination light EL is irradiated to the reticle _RT to perform exposure.
As a result, the reference pattern 74 ₁ is transferred onto the area S _1,2 on the wafer W in an overlapping manner. Also in this case, the exposure time required for transferring the reference pattern 74 ₁ can be shortened for the same reason as in the case of transferring the measurement pattern described above.

Thereafter, by repeating the inter-region stepping operation and the exposure operation similar to the above, the measurement pattern and the reference pattern similar to those in FIG. 6B are formed in the region S _{i, j} on the wafer W. A latent image is formed. Also in this case, the exposure time required for transferring the reference pattern 74 ₁ to each area S _{i, j} can be shortened.

In this way, all exposure is completed.
In the main controller 50, a wafer loader (not shown) is used.
And unload the wafer W from the Z tilt stage 58.
Connected to the chamber 11 inline.
The illustrated coater / developer (abbreviated as "C / D" below)
Send) to. Then, the development of the wafer W is performed in the C / D.
And the matrix is formed on the wafer W after the development.
Areas S arranged in a line _{i, j}The same arrangement as in Fig. 6 (B)
A resist image of the measurement pattern and the reference pattern is formed by
To be done.

After that, the wafer W which has been developed is C /
Then, the overlay error is measured for each region S _{i, j} by using an external overlay measuring device (registration measuring device), and based on this result, each measurement pattern 67 _i, Positional error (positional shift amount) of the resist image of _j with respect to the resist image of the corresponding reference pattern 74 _1.
Is calculated. There are various possible methods for calculating the positional deviation amount, but in any case, it is preferable to perform statistical calculation based on the measured raw data from the viewpoint of improving accuracy.

Then, for each region S _{i, j} , the amount of positional displacement (Δξ, Δη) of the measurement pattern with respect to the reference pattern in the X and Y two-dimensional directions is obtained.

Here, the wavefront of the projection optical system PL is calculated by calculation based on this position shift amount. As a premise, the physical relationship between the position shift amount (Δξ, Δη) and the wavefront is calculated as follows. A brief description will be given with reference to FIGS. 3 and 4.

FIG. 3 shows a measurement pattern 67._{k, l}About
Then, as representatively shown, the measurement pattern 67_{i, j}
(67_{k, l}) Of the diffracted light generated by
Opening 70 _{i, j} The light that has passed through the_{k, l}
Of the projection optical system
The position passing through the pupil plane of PL is different. That is, of the pupil plane
The wavefront at each position is the measurement pattern corresponding to that position.
67_{k, l}Corresponding to the wavefront of light through the position at
There is. And if the projection optical system PL has no aberration at all,
, Those wavefronts are the pupil planes of the projection optical system PL.
Is the code F₁The ideal wavefront as shown by
Surface). However, projection without aberrations
In the pupil plane, the example
For example, the curved wavefront F as shown by the dotted line₂Becomes
Therefore, the measurement pattern 67_{i, j}On the wafer W
Wave front F₂At a position shifted according to the inclination of the ideal wavefront of
It is imaged.

On the other hand, the reference pattern 74 ₁ (or 7
4 ₂ ) generates diffracted light, as shown in FIG.
Without being restricted by the pinhole-shaped opening, the light directly enters the projection optical system PL and is imaged on the wafer W through the projection optical system PL. Furthermore, this reference pattern 74
_Since exposure using ₁ is performed with the center of the reference pattern 74 ₁ being positioned on the optical axis of the projection optical system PL, most of the imaging light flux generated from the reference pattern 74 ₁ is an aberration of the projection optical system PL. The image is formed on the minute area including the optical axis without any positional deviation without being affected by.

Therefore, the positional deviation amount (Δξ, Δη) becomes a value that directly reflects the inclination of the wavefront with respect to the ideal wavefront, and conversely the wavefront can be restored based on the positional deviation amount (Δξ, Δη). In addition, the amount of positional deviation (Δξ,
As is clear from the physical relationship between Δη) and the wavefront, the wavefront calculation principle in this embodiment is based on the well-known Shack-Hart method.
It is the wavefront calculation principle of man itself.

Next, a method for calculating the wavefront based on the above-mentioned amount of positional deviation will be briefly described.

As described above, the positional deviation amount (Δξ, Δη) corresponds to the inclination of the wavefront, and by integrating this, the shape of the wavefront (strictly speaking, deviation from the reference surface (ideal wavefront)).
Is required. If the equation of the wavefront (deviation of the wavefront from the reference plane) is W (x, y) and the proportional coefficient is k, the relational expressions such as the following equations (1) and (2) are established.

[0100]

[Equation 1]

Since it is not easy to directly integrate the wavefront inclination given only by the amount of positional deviation, the surface shape is developed into a series and fitted to it. In this case, the series should be orthogonal. The Zernike polynomial is a series suitable for expanding an axisymmetric surface, and expands into a trigonometric series in the circumferential direction. That is, when the wavefront W is represented by the polar coordinate system (ρ, θ), the Zernike polynomial can be expanded as R _n ^m (ρ) as shown in the following expression (3).

[0102]

[Equation 2]

Since the specific form of R _n ^m (ρ) is well known (for example, it is described in a general textbook of optics), detailed description thereof will be omitted. Since it is an orthogonal system, the coefficients of each term, A _n ^m and B _n ^m, can be independently determined.
Cutting with a finite term corresponds to performing some sort of filtering.

In practice, the derivative is detected as the above-mentioned positional deviation amount, and therefore the fitting needs to be performed on the differential coefficient. Polar coordinate system (x = ρcos θ, y = ρs
in θ) is expressed by the following equations (4) and (5).

[0105]

[Equation 3]

Since the differential form of the Zernike polynomial is not an orthogonal system, the fitting must be performed by the least square method. The information (the amount of deviation) from one measurement pattern is X
And the number of measurement patterns is N (N is, for example, about 81 to 400),
The number of observation equations given by the above equations (1) to (5) is 2N.
(= About 162 to 800). From now on, for example, 27
Much smaller the error of each coefficient to determine the coefficients (the variation coefficients except A _{¹ 1,} B _{1 1} representing the tilt of the surface is accommodated in several nm).

Each term in the Zernike polynomial corresponds to an optical aberration. Moreover, the low-order terms almost correspond to Seidel aberrations. Therefore, the wavefront aberration of the projection optical system PL can be obtained by using the Zernike polynomial.

Therefore, in this embodiment, as described above,
Each area S obtained by_{i, j}Against the reference pattern for
Amount of misalignment of measuring pattern in X, Y two-dimensional direction
The data of (Δξ, Δη) is shown in FIG.
Is input to the main controller 50 via the input / output device 44 of
It Each area calculated from an external overlay measuring instrument
S _{i, j}Displacement data (Δξ, Δη) for
Can be input to the main controller 50 online.
Noh.

In any case, in response to the above input,
The CPU in the main controller 50 uses a predetermined calculation program to correspond to each region S _{i, j} based on the positional deviation amount (Δξ, Δη) according to the principle described above, that is, the projection optical system PL. wavefront corresponding to the first measurement point to the n-th measurement point in the visual field (wavefront aberration), wherein the calculation coefficient of each term of the Zernike polynomial, for example, the second term of the coefficient Z ₂ - coefficient Z ₃₆ of paragraph 36 To do.

In the exposure apparatus 10 of the present embodiment, at the time of manufacturing a semiconductor device, a reticle R for device manufacturing is loaded as a reticle on the reticle stage RST, and thereafter, reticle alignment and a so-called baseline of a wafer alignment system not shown. Measurement and EGA
Preparation work such as wafer alignment such as (enhanced global alignment) is performed. After that, the same step-and-repeat exposure is performed as in the measurement of the optical characteristics described above. However, in this case, stepping is performed in units of shots based on the wafer alignment result. Since the operation during exposure does not differ from that of a normal stepper, detailed description thereof will be omitted.

However, in the exposure apparatus 10, the maintenance is periodically performed, and at that time, the wavefront aberration is measured using the above-described measurement reticle R _{T according} to the procedure described above, and based on the measurement result. Thus, the projection optical system PL is adjusted. This adjustment is performed, for example, by the main control device 50 based on the measurement result of the wavefront aberration, astigmatism, coma aberration, distortion, field curvature (or focus), low-order aberration such as spherical aberration, that is, Seidel's 5 aberrations. Etc., and gives a command to the imaging characteristic correction controller 48 to correct these aberrations. As a result, the imaging characteristic correction controller 48 controls the applied voltage to a predetermined drive element that drives at least one predetermined movable lens of the movable lenses 13 _{1 to} 13 ₄ in at least one degree of freedom direction, and At least one of the position and the posture of the predetermined movable lens is adjusted, and the imaging characteristics of the projection optical system PL, such as distortion, field curvature, coma aberration, spherical aberration, and astigmatism, are corrected.

In this case, the relationship between the unit drive amount of each movable lens in the direction of each degree of freedom and the change amount of the wavefront aberration (the coefficient of each term of the Zernike polynomial) is obtained in advance and stored in a memory as a database. At the same time, an adjustment amount calculation program for calculating the adjustment amount of the imaging characteristic based on this database and the coefficient of each term of the Zernike polynomial may be prepared. This way,
In the main controller 50, when the measurement result of the wavefront aberration (calculated value of the coefficient of each term of the Zernike polynomial) is obtained, the above adjustment is performed using the database and the obtained measurement result of the wavefront aberration. An adjustment amount for driving the movable lenses 13 _{1 to} 13 ₄ in each of the degrees of freedom is calculated according to the amount calculation program, and a command value of this adjustment amount is given to the imaging characteristic correction controller 48. As a result, the image formation characteristic correction controller 48 controls the voltage applied to each drive element that drives the movable lenses 13 _{1 to} 13 ₄ in the respective degrees of freedom, and at least the positions and orientations of the movable lenses 13 _{1 to} 13 ₄ are controlled. One of them is adjusted almost at the same time, and image forming characteristics of the projection optical system PL, such as distortion, field curvature, and coma aberration,
Spherical aberration, astigmatism, etc. are corrected. Regarding coma aberration, spherical aberration, and astigmatism, not only low-order aberrations but also high-order aberrations can be corrected.

Next, a method of manufacturing the exposure apparatus 10 will be described.

In manufacturing the exposure apparatus 10, first, an illumination optical system 12 including optical elements such as a plurality of lenses and mirrors, a projection optical system PL, a reticle stage system including a large number of mechanical parts, a wafer stage system, and the like are provided. , Assembling each as a unit, and performing optical adjustments so that each unit exhibits the desired performance as a unit,
Make mechanical and electrical adjustments.

Next, the illumination optical system 12, the projection optical system PL, etc. are assembled in the exposure apparatus main body, and the reticle stage system, wafer stage system, etc. are attached to the exposure apparatus main body to connect wiring and piping.

Next, the illumination optical system 12 and the projection optical system PL
With respect to, the optical adjustment is further performed. This is because the optical characteristics of those optical systems, in particular, the projection optical system PL slightly change before and after assembling to the exposure apparatus main body. In the present embodiment, when the optical adjustment of the projection optical system PL is carried out after being incorporated in the exposure apparatus main body, the wavefront aberration of the projection optical system PL is measured by the procedure described above using the measurement reticle R _T described above. To do. And
Based on this wavefront aberration result, Seidel aberration and the like are corrected in the same manner as during the above-mentioned maintenance. Also,
If necessary, readjust the assembling of the lens or the like based on the higher-order aberration. If the desired performance cannot be obtained by the readjustment, it is necessary to reprocess some lenses. In order to easily reprocess the optical elements of the projection optical system PL, the above-mentioned wavefront aberration is measured before the projection optical system PL is incorporated into the exposure apparatus main body, and the optical processing that requires reprocessing is performed based on this measurement result. Identify the presence or absence of elements and their positions,
The reprocessing of the optical element and the readjustment of other optical elements may be performed in parallel.

Thereafter, further comprehensive adjustment (electrical adjustment, operation confirmation, etc.) is performed. This makes it possible to manufacture the exposure apparatus 10 of the present embodiment, which can accurately transfer the pattern of the reticle R onto the wafer W by using the projection optical system PL whose optical characteristics are adjusted with high accuracy. . It is desirable that the exposure apparatus be manufactured in a clean room where the temperature and cleanliness are controlled.

By the way, as in the present embodiment, based on the measurement result of the positional relationship between the image of the measurement pattern formed on the resist layer on the wafer and the image of the reference pattern, the optical characteristics (wavefront) of the projection optical system are measured. When calculating (e.g. aberration),
It is known that the measurement result of spherical aberration is different depending on the thickness of the resist layer. This is because the line width of the image formed on the resist layer is slightly different depending on the thickness of the resist layer. Therefore, it is desirable that the thickness of the resist layer be substantially constant when measuring the optical characteristics of the projection optical system. However, as a practical matter, it is not easy to always keep the thickness of the resist layer constant when the resist is applied onto the wafer using a spin coater or the like.

Therefore, when the optical characteristics of the projection optical system are measured by using the same measurement reticle as the above-mentioned measurement reticle R _T , the light-shielding portion (chrome layer) of each of the above-described measurement patterns is previously prepared. A plurality of types of measurement reticles having the same thickness as the light-shielding portion (chrome layer) of the reference pattern, that is, different illumination light transmittance, and having the same configuration as the above-described measurement reticle are prepared. Then, when measuring the optical characteristics of the projection optical system, prior to the start of the measurement, the thickness of the resist layer on the wafer used for measurement by the optical method or the contact needle method is measured, and based on the measurement result. Then, an appropriate measurement reticle in which the light shielding portion is set to the illumination light transmittance according to the thickness of the resist layer and the resist sensitivity is selected. Then, using the selected measurement reticle, the measurement pattern and the reference pattern are sequentially transferred onto the wafer in the same procedure as described above, and the wafer is developed. By doing so, it is possible to always keep the line widths of the measurement pattern and the reference pattern formed on the wafer within the range of the desired line width.

The reason is that, as described above, the light transmitted through the above-mentioned light-shielding portion is also radiated to the region on the wafer W corresponding to the light-shielding portion, which means that the transmittance of the light-shielding portion is changed. This is because it means that the film thickness of the resist layer after development can be controlled. Therefore, by using the above method of selecting an appropriate measurement reticle according to the film thickness on the wafer before development, the film thickness of the resist layer after development is always constant, and as a result, the desired line width is obtained. It is possible to obtain a resist image of.

The thickness of the above-mentioned light-shielding portion (chrome layer),
That is, instead of preparing a plurality of types of masks having different illumination light transmissivities and having the same configuration as the measurement reticle described above, a region without a pattern is prepared in the measurement reticle or the like and used as a measurement pattern or a reference pattern. The region and the substrate such as a wafer may be double-exposed. In this case, if the exposure is performed through a region having no pattern while adjusting the exposure amount, the same effect as when changing the transmittance of the light-shielding portion is obtained, and as a result, the above-mentioned light-shielding portion (chrome layer) is obtained. It is possible to achieve the same purpose as in the case where a plurality of masks having different illumination light transmittances are prepared.

Then, the amount of positional deviation of the resist image of each measurement pattern formed on the wafer with respect to the corresponding reference pattern is measured, and based on the measurement result, the optical characteristics of the projection optical system are measured. , For example, the wavefront aberration is calculated. As a result, it becomes possible to measure the spherical aberration that is not affected by the thickness of the resist layer based on the measurement result of the wavefront aberration.

Note that a reticle having a light-transmitting portion having a different transmittance is selected according to the thickness of the resist layer described above, in other words, the light-transmitting portion of the reticle has a different transmittance depending on the thickness of the resist layer. This method can be suitably applied to the measurement of spherical aberration by the conventional printing method using a measurement pattern.

As described above, according to this embodiment
And the pattern surface of the glass substrate 60 becomes the object surface (first surface).
In the state where it is positioned, the measurement lens is placed on the object plane side of the projection optical system PL.
Chickle R_TThe image plane of the projection optical system PL (second surface)
Wafer W with a photosensitive agent (resist) applied on its surface
Place. In this state, place on the pattern surface of the glass substrate 60.
A plurality of measurement patterns 67 arranged in a fixed positional relationship
_{i, j}However, when illuminated by the illumination light EL,
The illumination light emitted from the measurement pattern is reflected by the glass substrate 60.
Each of the aperture plates 66 arranged on the emission side with respect to the pattern surface
Measurement pattern 67 _{i, j}Was provided corresponding to
A plurality of pinhole-shaped openings 70_{i, j}Through each of
It is incident on the projection optical system PL and is transmitted through the projection optical system PL.
It is projected on the photosensitive layer (resist layer) on the roof W. this
At this time, each measurement pattern 67_{i, j}Part of the light-shielding part of
Since the transmittance is set to a certain level, the light is originally blocked.
The leaked light from the part that has a pinhole-shaped opening 70
_{i, j}And reaches the wafer W via the projection optical system PL,
The exposure of the resist on the surface of the wafer W is promoted. Therefore, the eyes
Transfer image of target line width measurement pattern, eg, resist
The irradiation time (exposure time) of the illumination light EL to obtain the image
It can be shortened.

Further, the reference pattern 74 ₁ (74 ₂ ) on the measurement reticle R _T is sequentially transferred to the resist layer on the wafer W by using the illumination light EL as a reference for the positional deviation of each measurement pattern 67 _{i, j.} To do. Since 74 ₁ (74 ₂₎ also shielding portion reference pattern is set to the transmittance of the extent through which some light, leakage light from the light-shielding portion promotes a photosensitive resist on the wafer W surface, the reference pattern 74 ₁ It is also possible to shorten the exposure time for the transfer of (74 ₂ ). However, the reference pattern 7
The light shielding portion 4 ₁ (74 ₂ ) does not necessarily have to transmit the illumination light EL. This is because the diffracted light generated by the reference pattern 74 ₁ (74 ₂ ) is not limited by the pinhole-shaped opening.

Then, the wavefront aberration is obtained as the optical characteristic of the projection optical system PL based on the amount of displacement of the resist image of each measurement pattern 67 _{i, j} with respect to the resist image of the corresponding reference pattern 74 ₁ (74 ₂ ). . In this case, as described above, the positional deviation amount is an amount that accurately reflects the optical characteristic of the projection optical system PL, and the optical characteristic of the projection optical system PL can be accurately obtained based on this amount. Is possible. Therefore, it is possible to improve the ability to measure the optical characteristics (wavefront aberration) of the projection optical system PL in terms of time and accuracy.

Further, according to the present embodiment, the wavefront aberration of the projection optical system PL is measured with high accuracy at the time of maintenance or the like, and the projection optical system PL is adjusted based on the measurement result of the wavefront aberration measured with high accuracy. Since it is adjusted, the optical characteristics of the projection optical system PL can be adjusted with high accuracy.

Furthermore, according to the present embodiment, the exposure apparatus 1
Even when 0 is manufactured, after the projection optical system PL is incorporated in the exposure apparatus main body, as described above,
Is measured, and the projection optical system PL is adjusted based on the measured wavefront aberration, so that the imaging characteristics of the projection optical system are adjusted with high accuracy. Therefore, the exposure apparatus 10 in which the image forming characteristics of the projection optical system are adjusted with high accuracy is manufactured, and exposure is performed using the exposure apparatus 10, whereby the reticle pattern is accurately transferred onto the wafer via the projection optical system PL. It becomes possible to transfer.

In the above embodiment, the case where the measurement pattern and the reference pattern are formed on the same measurement reticle R _T has been described, but the present invention is not limited to this.
The reference pattern may be formed on a reticle (mask) different from the measurement pattern.

<< Second Embodiment >> Next, a second embodiment of the present invention will be described with reference to FIGS. 8 and 9A to 9C. Here, the same reference numerals are used for the same or equivalent components as those in the first embodiment described above, and the description thereof will be simplified or omitted.

In the second embodiment, when measuring the optical characteristics of the projection optical system PL, specifically, the wavefront aberration, the measurement reticle R ′ shown in FIG. 8 is used instead of the above-mentioned measurement reticle R _{T. It} is characterized in that _T is used, and correspondingly, a reference wafer W _F as a reference substrate shown in FIG. 9A is used.

[0132] measurement reticle R _'T is configured in the same manner is basically the measurement reticle R _T described above, the lower surface of the glass substrate 60 (pattern surface), the reference pattern is formed at all However, correspondingly, there is a difference in that the lens holding member 62 is not provided with an opening forming a passage of illumination light with respect to the reference pattern. The other parts are configured similarly to the measurement reticle R _T.

In the second embodiment, instead of providing the reference pattern on the measurement reticle R ′ _T , the reference wafer W _F provided with the reference pattern is used.
As shown in FIG. 9A, the reference wafer W _F has a rectangular division area obtained by multiplying a rectangular area including all the measurement patterns 67 _{i, j} on the measurement reticle R ′ _T by the projection magnification. SA _{1 to} SA _m (m = 8 in the case of FIG. 9A) are preformed wafers. Each partition area SA is shown in FIG.
As shown in the enlarged view of the partitioned area SA _m in (B), the reference pattern 76 _{i, j} is previously formed in each area S _{i, j of} the matrix arrangement corresponding to the measurement pattern 67 _{i, j.} ing. The reference pattern 76 _{i, j} is shown in FIG.
As shown in an enlarged view in (C), a two-dimensional square pattern is arranged with a pitch corresponding to the measurement patterns 67 _{i, j} similar to the reference patterns 74 ₁ and 74 _{2 in the first} embodiment. (However, in this case, each square pattern has an arrangement and size corresponding to the measurement pattern reduced according to the projection magnification).

In the second embodiment, the projection optical system P
When measuring the wavefront aberration of the L, resist is coated on the reference wafer W _F, and loads the reference wafer W _F on the wafer stage WST. Then, the measurement pattern 67 _{i, j} of the reticle R ′ _T is transferred onto at least one divided area SA on the reference wafer W _{F by} the same procedure as in the first embodiment described above. Then, the reference wafer W _F is developed by C / D (not shown). After this development, the reference wafer W _F
A resist image of the measurement pattern 67 _{i, j} and the reference pattern 76 _{i, j} is formed on each of the areas S _{i, j} arranged in a matrix in the same manner as in FIG. 6B.

After that, the wafer W which has been developed is C /
The amount of displacement (Δξ, Δη) of the measurement pattern in the two-dimensional X and Y directions with respect to the reference pattern for each region S _{i, j} taken out from D and using an external overlay measurement device (registration measurement device). Ask for. Then, in the same procedure as described above, based on the positional deviation amount (Δξ, Δη),
Wavefront aberration is measured as an optical characteristic of the projection optical system PL.

[0136] In this case, the measurement pattern 67 _i, the image of the _j, as described above, depending on the inclination with respect to the ideal wavefront of the wavefront of each measurement pattern 67 _i, light through a _j by the projection optical system PL The image is formed at a position that is offset. On the other hand, since the reference wafer W _F can be manufactured in advance _, the arrangement of the reference patterns 76 _{i, j} can be made almost as designed by using a highly accurate pattern drawing device or the like. Therefore, the amount of positional deviation of the transferred image of each measurement pattern 67 _{i, j} on the reference wafer W _F with respect to the corresponding reference pattern 76 _{i, j} is an amount that accurately reflects the optical characteristics of the projection optical system PL. Based on this amount, it is possible to accurately obtain the optical characteristics of the projection optical system PL, for example, the wavefront aberration.

[0137] The present also in the second embodiment performs the maintenance of the exposure apparatus periodically, in time, using the measurement reticle R _'T described above is performed the measurement of the wavefront aberration by the procedure described above, Based on the measurement result, the projection optical system PL is adjusted as in the first embodiment. Further, also in the manufacturing process of the exposure apparatus, the measurement of the wavefront aberration after assembling the projection optical system PL to the exposure apparatus main body and the adjustment of the projection optical system PL based on the measurement are performed in the same manner as in the first embodiment. .

According to the second embodiment described above,
It is possible to obtain the same effect as that of the first embodiment described above. In addition to this, in the present embodiment, when measuring the optical characteristics of the projection optical system PL, it suffices to transfer the measurement pattern. Therefore, the transfer of the reference pattern (normal transfer is a step-and-repeat method). Performed) is unnecessary, and the measurement time can be shortened accordingly, and the time required for measuring the optical characteristics of the projection optical system can be further shortened, and the adjustment time of the projection optical system can be further shortened.

When the reference wafer is used as in the second embodiment, the light-shielding portion of each measurement pattern does not necessarily have the transmittance of the illumination light. Even in such a case, the transfer of the reference pattern performed by the step-and-repeat method becomes unnecessary, and the measurement time can be shortened accordingly.

In the second embodiment, the case where the reference pattern is previously formed on the reference wafer has been described. However, the present invention is not limited to this, and the reference wafer on which the measurement pattern is previously formed is prepared. The reference pattern may be transferred to the resist layer on the reference wafer to measure the amount of positional deviation. Even in such a case, the time required to measure the optical characteristics of the projection optical system PL can be significantly reduced.
Since the measurement pattern is transferred onto the wafer through the pinhole-shaped opening, the exposure itself is one time, but it is equal to or longer than the transfer time of the reference pattern performed by the step-and-repeat method. It takes more time. Therefore, if the time required for transferring the measurement pattern onto the wafer is not necessary, it is clear that the time required for exposure can be greatly reduced.

In the optical characteristic measuring mask of the present invention, it is not always necessary to provide a condenser element such as a condenser lens. As the condenser element, a Fresnel lens or other optical elements may be used in addition to the condenser lens.

In each of the above embodiments, after the measurement pattern (and the reference pattern) is transferred onto the wafer W,
Although the wavefront aberration of the projection optical system PL is calculated based on the measurement result of the resist image obtained by developing the wafer, the invention is not limited to this, and the measurement pattern and the reference pattern of the measurement pattern formed on the resist layer are not limited to this. The latent image or the image obtained by etching the wafer may be measured. Even in such a case, the amount of displacement from the reference position of the latent image or etching image of the measurement pattern (for example, the projected position of the designing measurement pattern or the position of the latent image or etching image of the reference pattern) is measured. If so, it is possible to obtain the wavefront aberration of the projection optical system based on the measurement result in the same procedure as in the above-described embodiments. Further, in the above-described embodiment, the amount of positional deviation described above is measured using the overlay measuring device, but other than that, for example, an alignment sensor or the like provided in the exposure apparatus may be used.

Further, in each of the above-mentioned embodiments, a plurality of measurement patterns are transferred onto the wafer by one exposure operation, but they may be transferred in two or more exposure operations separately. The reticle may be moved during the exposure operation. In this case, at least one measurement pattern may be formed on the reticle without forming a plurality of measurement patterns on the reticle corresponding to the projection visual field (illumination light irradiation area) of the projection optical system PL. Further, although the measurement reticle is used in each of the above-described embodiments, for example, at least one measurement pattern and the reference pattern are formed on the reticle stage RST, and a pinhole shape is used when measuring the optical characteristics of the projection optical system. The plate on which the opening is formed may be arranged close to the pattern surface of the reticle, or a pinhole plate may be provided on the lower surface of the reticle stage close to the measurement pattern. That is, the optical characteristic measuring mask of the present invention is not limited to a mask or a reticle, and is a concept including a pattern plate provided on, for example, a reticle stage.

When an optical characteristic measuring mask other than the above-described measuring reticle is used together with the reference wafer as in the second embodiment, at least one measuring element is used for the optical characteristic measuring mask. Only the use pattern may be formed.

Further, in each of the above embodiments, the case where the wavefront aberration is obtained as the optical characteristic of the projection optical system has been described. However, based on the amount of displacement of the projection position of each measurement pattern from the predetermined reference position. The optical characteristics are not limited to wavefront aberrations as long as they are required.

As in the second embodiment, when a reference wafer is used, the reference pattern is transferred onto the wafer using an exposure device such as a stepper instead of a high-precision pattern drawing device. May be manufactured. However, in such a case, the positional relationship (interval, etc.) of the plurality of reference patterns on the reference wafer is measured, and the projection optical system PL is also taken into consideration, for example, in consideration of the measurement result.
It is desirable to obtain the optical characteristics of As a result, the measurement error of the optical characteristics of the projection optical system PL due to the position error of the reference pattern on the reference wafer can be reduced. In this case, the above-mentioned positional deviation amount (Δξ, Δη) is obtained for each measurement pattern in consideration of the measurement result of the positional relationship of the plurality of reference patterns, and the optical characteristic of the projection optical system is determined based on this positional deviation amount. It may be calculated, or when the positional deviation amount (Δξ, Δη) is calculated, the positional relationship of the reference pattern is not particularly considered, and the projection optical system PL measured (obtained) based on the positional deviation amount is used. The measurement result of the optical characteristic may be corrected using the measurement result of the positional relationship of the plurality of reference patterns.

Furthermore, when the measurement reticle R _T or the measurement reticle R ′ _T is used as the optical characteristic measurement mask, the positional relationship (interval, etc.) of a plurality of measurement patterns on these measurement reticles is measured. Incidentally, it is desirable to obtain the optical characteristics of the projection optical system PL in consideration of this measurement result as well. Accordingly, it is possible to reduce the measurement error of the optical characteristics of the projection optical system PL caused by the position error (drawing error) of the measurement pattern on the measurement reticle. Also in this case, as in the above case, the positional deviation amount (Δξ, Δ
When obtaining η), the position error of the measurement pattern may be taken into consideration, or the measurement result of the optical characteristics may be corrected using the position error of the measurement pattern.

In each of the above embodiments, when the optical characteristics of the projection optical system PL are measured using the measurement reticle R _T or R ′ _T , the measurement pattern and the reference pattern are transferred onto the wafer, or the measurement pattern is measured. Although the printing method of transferring the use pattern onto the reference wafer is adopted, the invention is not limited to this, and the aerial image measuring method of measuring the position of the aerial image (projected image) may be adopted.

That is, when measuring the optical characteristics of the projection optical system PL, the measurement reticle R is placed on the reticle stage RST in the same procedure as in the first embodiment described above.
_{After T} (or R ′ _T ) is placed and reticle alignment is performed, the measurement reticle R _T (or R ′ _T ) is illuminated and a plurality of measurement patterns 67 _{i, j} are formed in a pinhole shape. The image is projected through the aperture 70 _{i, j} and the projection optical system PL. Then, the amount of positional deviation (Δξ, Δη) from the predetermined reference position of the projected image of each measurement pattern 67 _{i, j} on the image plane (or its conjugate plane) is obtained, and based on this positional deviation amount, The optical characteristics (for example, wavefront aberration) of the projection optical system may be obtained by the same procedure as in the first and second embodiments. In this case, an array sensor (CCD or the like) is arranged on the image plane (second plane) of the projection optical system PL or its conjugate plane, and the positional deviation amount of the projected image of the measurement pattern with respect to each sensor (pixel) is calculated as above. It may be obtained as a positional deviation amount. In this case, since the light-shielding portion of each measurement pattern is set to have a transmittance that allows some light to pass therethrough, leakage light from the portion where the light is originally shielded also has a pinhole-shaped opening and projection optical system. To reach the image plane via. Further, for the same reason as described above, the image of each measurement pattern is formed at a position displaced according to the inclination of the wavefront of the light passing through each measurement pattern with respect to the ideal wavefront. The amount accurately reflects the optical characteristic of the projection optical system PL, and based on this amount, the optical characteristic of the projection optical system can be accurately obtained.

In this case, a reference plate on which at least one reference pattern is formed is arranged on the image surface (second surface) or its conjugate surface, and the positional deviation amount of the projected image of each measurement pattern with respect to the reference pattern is determined. You may ask.

Further, when the reference plate is arranged on a surface substantially conjugate with the second surface (image surface) of the projection optical system, the optical characteristics of the optical system which makes the image surface and the reference plate conjugate with each other are measured. Aside
For example, it is preferable to use the measurement result to obtain the positional deviation amount described above or to correct the measurement result of the optical characteristic of the projection optical system. As a result, the measurement error of the optical characteristics due to the optical system can be reduced. Further, a plurality of reference patterns may be formed on the reference plate in substantially the same positional relationship as the plurality of measurement patterns. In this case, it is possible to shorten the measurement time of the amount of positional deviation described above. In this case, the positional relationship (interval, etc.) of the plurality of reference patterns is measured, and the above-mentioned positional deviation amount is obtained for each measurement pattern using this measurement result, or the measurement result of the optical characteristics of the projection optical system is obtained. It is desirable to correct Accordingly, it is possible to reduce the measurement error of the optical characteristic due to the position error of the reference pattern on the reference plate. further,
When the numbers of the measurement patterns and the reference patterns are different, for example, when the number of the reference patterns is smaller than that of the measurement patterns, it is necessary to move the reference plate within the second surface (image surface) or its conjugate plane. At this time, since a positioning error may occur when the reference plate moves, for example, the positioning error is measured for each projection position of the measurement pattern and, for example, the above-mentioned measurement result is used to determine the amount of positional deviation, or It is preferable to correct the measurement result of the characteristic.

In each of the above embodiments, the case where the present invention is applied to a stepper has been described. However, the present invention is not limited to this, and the mask and substrate disclosed in, for example, US Pat. No. 5,473,410 may be used. The present invention can also be applied to a scanning type exposure apparatus that moves in synchronism to transfer a mask pattern onto a substrate.

The application of the exposure apparatus is not limited to the exposure apparatus for semiconductor manufacturing, and for example, an exposure apparatus for liquid crystal for transferring a liquid crystal display element pattern onto a rectangular glass plate, a thin film magnetic head, a micromachine. And DNA
It can be widely applied to exposure apparatuses for manufacturing chips and the like. Further, not only microdevices such as semiconductor elements, but also glass substrates or silicon wafers for manufacturing reticles or masks used in light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern onto a substrate.

In addition, the light source of the exposure apparatus of the above embodiment is
Not only UV pulse light sources such as F ₂ laser light source, ArF excimer laser light source, KrF excimer laser light source, but also ultra-high pressure mercury lamps that emit g-line (wavelength 436 nm), i-line (wavelength 365 nm) and other bright lines can be used. Is.

Further, a single-wavelength laser light in the infrared region or visible region emitted from a DFB semiconductor laser or a fiber laser is amplified by a fiber amplifier doped with erbium (or both erbium and ytterbium), and a nonlinear It is also possible to use a harmonic wave whose wavelength is converted into ultraviolet light using an optical crystal. Further, the magnification of the projection optical system is not limited to a reduction system, and may be a unity magnification system or a magnification system.

As for the semiconductor device, the step of designing the function / performance of the device, the step of producing a reticle based on this design step, the step of producing a wafer from a silicon material, and the reticle of the reticle by the exposure apparatus of the above-described embodiment. Transferring the pattern to the wafer,
It is manufactured through a device assembly step (including a dicing process, a bonding process, a packaging process), an inspection step, and the like.

[0157]

As described above, according to the optical characteristic measuring mask of the present invention, the time required for the exposure can be shortened, and the total time required for measuring the optical characteristic can be shortened. There is an effect that can be.

Further, the optical characteristic measuring method according to the present invention has an effect that the measuring ability can be improved.

Further, according to the method of adjusting the projection optical system of the present invention, the optical characteristics of the projection optical system can be adjusted with high accuracy.

Further, according to the method of manufacturing the exposure apparatus of the present invention, it is possible to manufacture the exposure apparatus capable of accurately transferring the mask pattern onto the substrate.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus according to a first embodiment.

FIG. 2 is a schematic perspective view showing a measurement reticle.

FIG. 3 is a diagram showing a schematic view of an XZ section in the vicinity of the optical axis of a measurement reticle in a state of being mounted on a reticle stage together with a schematic diagram of a projection optical system.

FIG. 4 is a diagram showing, together with a schematic diagram of a projection optical system, a schematic diagram of an XZ cross section in the vicinity of the −Y side end portion of a measurement reticle in a state of being loaded on a reticle stage.

5A is a diagram showing a measurement pattern formed on the measurement reticle of the first embodiment, and FIG.
FIG. 6B is a diagram showing a reference pattern formed on the measurement reticle of the first embodiment.

6A is a diagram showing a reduced image (latent image) of a measurement pattern formed at a predetermined interval on a resist layer on a wafer, and FIG. 6B is a diagram showing FIG. FIG. 7A is a diagram showing a positional relationship between the latent image of the measurement pattern and the latent image of the reference pattern.

FIG. 7A is a diagram showing a light intensity distribution immediately below a pattern surface focused on one line pattern portion forming an arbitrary measurement pattern on a measurement reticle R _T ; FIG. 7B shows the case where the transmittance of the light shielding part is 0.
It is a figure which shows the distribution of the light intensity corresponding to (A) as a comparative example.

FIG. 8 is a schematic perspective view showing a measurement reticle according to a second embodiment.

FIG. 9A to FIG. 9C are views for explaining a reference wafer.

[Explanation of symbols]

10 ... Exposure device, 60 ... Glass substrate (pattern forming member), 65 _{i, j} ... Condensing lens (condensing element), 66 ... Aperture plate, 67 _{i, j} ... Measurement pattern, 70 _{i, j} ... Pinhole -Shaped apertures, 74 ₁ , 74 ₂ ... Reference pattern, EL ... Illumination light,
PL ... projection optical system, R ... reticle (mask), R _T ... measurement reticle (optical characteristic measuring mask), W ... wafer (substrate), W _F ... reference wafer (reference substrate).

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ identification code FI theme code (reference) G03F 7/20 521 G03F 9/00 H 9/00 H01L 21/30 516A 515F

Claims (14)

[Claims] 1. An optical characteristic measuring mask used for measuring an optical characteristic of a projection optical system for projecting a pattern on a first surface onto a second surface, wherein a plurality of measuring patterns are provided at predetermined positions. A pattern forming member having a pattern surface arranged in relation to each other; an opening formed on the emitting side of the pattern forming member with respect to the pattern surface, and having a plurality of pinhole-shaped openings respectively corresponding to the respective measurement patterns A mask for optical characteristic measurement, comprising a plate, and the light-shielding portion of each of the measurement patterns is set to have a transmittance that allows a part of light to pass therethrough. 2. The optical characteristic measurement according to claim 1, further comprising a plurality of light-collecting elements arranged on the incident side of the pattern forming member so as to correspond to each of the plurality of measurement patterns. Mask. 3. The optical characteristic measuring mask according to claim 1, wherein the pattern forming member further has a reference pattern serving as a reference for positional deviation of projection positions of the respective measurement patterns. 4. The optical characteristic measuring mask according to claim 3, wherein the reference pattern is set to have such a transmittance that the light shielding portion allows a part of light to pass therethrough. 5. An optical characteristic measuring method for measuring an optical characteristic of a projection optical system for projecting a pattern on a first surface onto a second surface, wherein a plurality of measurements are performed on the first surface in a predetermined positional relationship. And a reference substrate on which a plurality of reference patterns are previously formed on the second surface in a positional relationship corresponding to the positional relationship of the plurality of measurement patterns, and the plurality of measurement patterns are arranged. The second illuminating light is illuminated by illuminating light, and each of the illuminating lights generated from each of the plurality of measurement patterns is passed through a pinhole provided corresponding to each of the measurement patterns and the projection optical system. Forming a transfer image of each of the measurement patterns on a photosensitive layer on the reference substrate by projecting onto the reference substrate on a surface; Correspondence of the transfer image of each of the measurement patterns on the reference substrate Measurement step and obtaining the optical characteristics of the projection optical system based on the positional deviation amount from the reference pattern that; optical characteristic measuring method comprising. 6. An optical characteristic measuring method for measuring the optical characteristic of a projection optical system using the optical characteristic measuring mask according to claim 1 or 2, wherein the optical characteristic measuring method is arranged on the first surface by illumination light. The mask for optical characteristic measurement is illuminated, and the plurality of measurement patterns are arranged on the second surface via a pinhole provided corresponding to each measurement pattern and the projection optical system. A transfer step of transferring to the photosensitive layer on the substrate; a measurement step of obtaining optical characteristics of the projection optical system based on a displacement amount of the transfer image of each of the measurement patterns from a predetermined reference position;
Optical characteristic measuring method including. 7. In the transfer step, as the substrate, a reference substrate in which a plurality of reference patterns are formed in advance in a positional relationship corresponding to the positional relationship of the plurality of measurement patterns is used. 7. The optical characteristic of the projection optical system is obtained based on the amount of displacement of the transfer image of the measurement pattern from the corresponding reference pattern.
The optical characteristic measuring method described in. 8. An optical characteristic measuring method for measuring the optical characteristic of a projection optical system using the optical characteristic measuring mask according to claim 3 or 4, wherein the optical characteristic measuring method is arranged on the first surface by illumination light. The mask for optical characteristic measurement is illuminated, and the plurality of measurement patterns are arranged on the second surface via a pinhole provided corresponding to each measurement pattern and the projection optical system. A first transfer step of transferring to a photosensitive layer on a substrate; using the illumination light, the reference pattern on the optical characteristic measuring mask as a reference for displacement of each of the measuring patterns, the photosensitive layer on the substrate And a second transfer step of sequentially transferring to each of the measurement patterns; and a measurement step of obtaining the optical characteristics of the projection optical system based on the amount of positional deviation of the transfer image of each measurement pattern from the corresponding reference pattern. . 9. The optical characteristic according to claim 5, wherein in the measuring step, a wavefront aberration of the projection optical system is calculated based on a calculation result of the positional deviation amount. Measuring method. 10. An optical characteristic measuring method for measuring an optical characteristic of a projection optical system for projecting a pattern on a first surface onto a second surface, wherein a predetermined measuring pattern is formed, A step of preparing a plurality of measurement masks in which the light-shielding portions have different transmittances; a step of measuring the thickness of the photosensitive layer on the substrate for transferring the measurement pattern; Selecting a specific measurement mask from the plurality of measurement masks according to the thickness; arranging the specific measurement mask on the first surface and illuminating with illumination light; Transferring the measurement pattern on the measurement mask to the photosensitive layer on the substrate arranged on the second surface via the projection optical system; Of the projection optical system based on the measurement result Process and of calculating the academic characteristics; optical property measurement method comprising. 11. An optical characteristic measuring method for measuring an optical characteristic of a projection optical system using the optical characteristic measuring mask according to claim 1 or 2, wherein the optical characteristic is arranged on the first surface. While illuminating the measurement mask, the plurality of measurement patterns are projected through the pinhole-shaped opening and the projection optical system, respectively, and the measurement patterns are projected on the second surface or the conjugate surface thereof. An optical characteristic measuring method, characterized in that the optical characteristic of the projection optical system is measured based on a displacement amount of an image from a predetermined reference position. 12. A reference plate on which at least one reference pattern is formed is arranged on the second surface or a conjugate surface thereof, and a positional deviation amount of a projected image of each measurement pattern with respect to the reference pattern is obtained. The optical characteristic measuring method according to claim 11. 13. A step of measuring an optical characteristic of a projection optical system using the optical characteristic measuring method according to any one of claims 5 to 12; and the projection optical system based on a measurement result of the optical characteristic. Adjusting the projection optical system. 14. A method of manufacturing an exposure apparatus for manufacturing an exposure apparatus for transferring a pattern of a mask onto a substrate via a projection optical system, wherein the optical characteristic measurement according to any one of claims 5 to 12. A method of manufacturing an exposure apparatus, comprising: measuring an optical characteristic of the projection optical system using a method; and adjusting the projection optical system based on the measured optical characteristic.