JP6625711B2 - Curvature measuring device and curvature measuring method - Google Patents

Description

  The present invention relates to a curvature measurement device and a curvature measurement method.

Conventionally, IGBT (Insulated Gate Bipolar Transi)
In a manufacturing process of a semiconductor element requiring a crystal film having a relatively large thickness, such as a power device such as an insulated gate bipolar transistor (storage), a single crystal thin film is formed by vapor phase growth on a substrate such as a semiconductor wafer. An epitaxial growth technique for forming a film is used. In a film forming apparatus used for this epitaxial growth technique, a substrate such as a wafer is placed in a film forming chamber maintained at normal pressure or reduced pressure. Then, while the substrate is heated, a gas (raw material gas) serving as a raw material for film formation is supplied into the film formation chamber. As a result, a chemical reaction such as a thermal decomposition reaction or a hydrogen reduction reaction of the source gas occurs on the surface of the substrate, and an epitaxial film is formed on the substrate.

In this film forming apparatus, a curvature measuring device (warpage measuring device) for measuring a curvature of a substrate as a measurement object is used. This curvature measuring device is mainly used at the time of optimizing a process procedure or the like, but in recent years, it is also used in a mass production device, and constant warpage monitoring is required. For example, in gallium nitride (GaN) film formation on 8-inch silicon,
In addition to differences in the thermal expansion coefficients of silicon and GaN thin films and large mismatches in crystal lattice constants, there are also film preparation conditions that cause a large temperature range, so it is very difficult to monitor how much the wafer is warped during film formation. It has become important. If the warpage monitoring is neglected, the quality of the product is degraded due to the tearing of the wafer or the generation of fine cracks in the thin film after the temperature is lowered during or after the film formation. Therefore, warpage monitoring is indispensable in optimizing a process procedure prior to mass production, but is required for quality maintenance even in a mass production situation in which a state in a film forming chamber changes little by little.

At present, the mainstream curvature measuring device allows at least two laser beams to be incident on a substrate in parallel through a window of a film forming chamber, reflected by the substrate, and returned through the aforementioned window. The position of the laser beam is detected, and the interval between them is read. Even when three or more laser beams are used, there is no difference in principle from the case where two laser beams are used. For simplicity, a case where two laser beams are used will be described below. As a method for detecting two laser beams, a two-point batch CCD system in which two laser beams are collectively detected by a two-dimensional CCD (charge coupled device) is generally employed. In this method, two laser beams are incident on the same element surface (light receiving surface),
The laser light is obtained as two points in the pixel. Then, the distance between the two points is calculated by image processing and converted into a curvature.

JP-A-10-78310

However, in the above-described two-point collective CCD method, when the warpage is large, the two points may coincide with each other, and the distance between the two points may not exist. For this reason, the curvature cannot be measured even though the curvature itself exists. Further, even when the two points do not coincide with each other, the S / N ratio (S / N) deteriorates in an area where warpage is large because of the CCD resolution. Further, when it is necessary to make the space between the two points narrow in order to reduce the window through which the two laser beams pass, the condition becomes worse and the SN ratio worsens.

The problem to be solved by the present invention is to provide a curvature measuring device and a curvature measuring method capable of suppressing the curvature measurement failure and improving the curvature measurement accuracy.

The first curvature measuring device according to the embodiment of the present invention includes a light emitting unit that emits a laser beam, and a laser beam emitted by the light emitting unit, the first laser beam having a different polarization direction and a different traveling direction. A first polarizing beam splitter for splitting the laser beam into a second laser beam;
A reflecting portion that reflects one of the first laser light and the second laser light so that the laser light travels in parallel to the object to be measured; and a first laser light that is specularly reflected by the object to be measured. Second
A second polarization beam splitter that transmits one of the laser beams and reflects the other in a direction different from the traveling direction of the one, and a second polarization beam splitter that has been reflected by the second polarization beam splitter. One-dimensional first detecting the incident position of the transmitted first laser light
And a one-dimensional second position detecting element for detecting an incident position of the second laser beam transmitted through the second polarizing beam splitter or reflected by the second polarizing beam splitter.

In addition, the second curvature measuring device according to the embodiment of the present invention includes a light emitting unit that emits laser light, and a first laser that emits a laser beam emitted by the light emitting unit, the first laser having a different polarization direction and a different traveling direction. A first polarization beam splitter for separating light and a second laser beam, and a reflection unit for reflecting the second laser beam such that the first laser beam and the second laser beam travel in parallel to the object to be measured. A second polarization beam splitter that transmits one of the first laser light and the second laser light traveling toward the measurement object; and a first polarization beam splitter and a second laser beam traveling toward the measurement object.
And a quarter-wave plate through which the first laser light and the second laser light that are specularly reflected by the measurement object pass and a quarter-wave plate that is specularly reflected by the measurement object A first position detecting element and a second position detecting element for detecting respective incident positions of the passed first laser light and second laser light are provided.

In the second curvature measuring device, when the first laser beam traveling toward the measurement target passes through the second polarization beam splitter, the second polarization beam splitter is specularly reflected by the measurement target. The reflector reflects the first laser light that has passed through the quarter-wave plate and reflects the second laser light that has been specularly reflected by the measurement object and has passed through the quarter-wave plate. The position detecting element detects an incident position of the first laser light reflected by the second polarizing beam splitter, and the second position detecting element detects an incident position of the second laser light reflected by the reflecting section. It is desirable to detect.

In the second curvature measuring device, when the second laser beam traveling toward the measurement object passes through the second polarization beam splitter, the first polarization beam splitter is specularly reflected by the measurement object. The second polarizing beam splitter reflects the first laser beam that has passed through the quarter-wave plate, and reflects the second laser beam that has been specularly reflected by the object to be measured and passed through the quarter-wave plate. The first position detecting element detects an incident position of the first laser beam reflected by the first polarizing beam splitter, and the second position detecting element detects the incident position of the first laser beam reflected by the second polarizing beam splitter. It is desirable to detect the incident position of the second laser light.

In the first or second curvature measuring device, the displacement amount of the incident position of the first laser beam detected by the first position detecting element and the second position detected by the second position detecting element. The difference between the amount of displacement of the incident position of the laser light is calculated, and the amount of change in curvature of the measurement object is calculated from the correlation between the calculated difference and the individual optical path lengths of the first laser light and the second laser light. It is desirable to further include a calculation unit.

In the first or second curvature measuring device, the first position detecting element and the second position detecting element may include two lines of the first laser light and the second laser light reflected by the measurement object. It is desirable to detect the shortest distance displacement in minutes.

Further, in the first or second curvature measuring device, the first laser light is condensed in a direction perpendicular to the element row direction of the first position detection element, and the second laser light is detected in the second position detection. It is desirable to further include a condenser lens that collects light in a direction perpendicular to the element row direction of the elements.

Also, in the first or second curvature measuring device, the light emitting unit may be a laser
It is desirable to emit laser light having a wavelength of less than nm.

Further, in the first or second curvature measuring device, the first position detecting element has a first light receiving surface on which the first laser light is incident, and the first light receiving surface is formed by the method. The line direction is inclined at least 10 degrees from the optical axis of the first laser light, and the second position detection element has a second light receiving surface on which the second laser light is incident, and the second light receiving surface Preferably, the surface has a normal direction inclined at least 10 degrees from the optical axis of the second laser beam.

In the first or second curvature measuring device, the first laser light is extended in a direction perpendicular to the element row direction of the first position detecting element, and the second laser light is transmitted to the second position detecting element. It is desirable to further include a molded portion that extends in a direction perpendicular to the element row direction.

In the first curvature measuring method according to the embodiment of the present invention, the step of emitting the laser beam by the light emitting unit and the step of converting the laser beam emitted by the light emitting unit into the first and second directions different in the polarization direction and the traveling direction, respectively. Separating the first laser beam and the second laser beam into a laser beam and a second laser beam by the first polarizing beam splitter; A step of reflecting one of the second laser beams by the reflecting portion, and transmitting one of the first laser beam and the second laser beam mirror-reflected by the object to be measured, and transmitting the other to the one of the one laser beam. Reflecting the second laser beam in a direction different from the traveling direction by the second polarizing beam splitter; and determining the incident position of the first laser beam reflected by the second polarizing beam splitter or transmitted through the second polarizing beam splitter. A step of detecting the original first position sensitive detector, the reflected by transmitted through the second polarization beam splitter or the second polarization beam splitter 2
Detecting the incident position of the laser beam by the one-dimensional second position detecting element.

Further, in the second curvature measuring method according to the embodiment of the present invention, the step of emitting the laser beam by the light emitting unit and the step of causing the laser beam emitted by the light emitting unit to have the first and second directions different from each other in the polarization direction and the traveling direction, respectively. Separating the first laser beam and the second laser beam into a second laser beam and a second laser beam by using a first polarizing beam splitter. A step of reflecting by the reflector, a step of transmitting one of the first laser light and the second laser light traveling toward the measurement object by the second polarization beam splitter, and traveling toward the measurement object. Passing the first laser light and the second laser light through a 波長 wavelength plate, and passing the first laser light and the second laser light mirror-reflected by the object to be measured through the 波長 wavelength plate; Specular reflection by the measurement object And a step of detecting by a first laser beam and the second laser beam of each of the incident positions, respectively a first position detecting element and a second position detecting element passed through the quarter-wave plate Te.

In the second curvature measurement method, when the first laser light traveling toward the measurement object passes through the second polarization beam splitter, the first laser light is specularly reflected by the measurement object and passes through the quarter-wave plate. The first laser beam thus reflected is reflected by the second polarization beam splitter and detected by the first position detecting element, and the second laser beam that has been specularly reflected by the object to be measured and passed through the quarter-wave plate is reflected. It is desirable that the light is reflected by the portion and detected by the second position detecting element.

In the second curvature measurement method, when the second laser beam traveling toward the measurement object passes through the second polarization beam splitter, the second laser beam is specularly reflected by the measurement object and passes through the quarter-wave plate. The first laser beam reflected by the first polarizing beam splitter is detected by the first position detecting element, and the second laser beam that has been specularly reflected by the object to be measured and passed through the quarter-wave plate is converted to the second laser beam. It is desirable that the light is reflected by the second polarizing beam splitter and detected by the second position detecting element.

According to the aspect of the invention, it is possible to suppress the curvature measurement from being disabled and to improve the curvature measurement accuracy.

FIG. 1 is a diagram illustrating a schematic configuration of a film forming apparatus according to a first embodiment. It is a front view showing the schematic structure of the curvature measuring device concerning a 1st embodiment. It is a front view showing the modification 1 of the curvature measuring device concerning a 1st embodiment. It is a side view showing the schematic structure of the curvature measuring device concerning a 1st embodiment. FIG. 3 is an explanatory diagram for explaining a laser beam interval on a substrate surface according to the first embodiment. 5 is a graph showing a relationship between an incident angle and a reflectance of S-polarized light and P-polarized light according to the first embodiment. It is a front view showing the schematic structure of the curvature measuring device concerning a 2nd embodiment. It is a front view showing the schematic structure of the curvature measuring device concerning a 3rd embodiment. It is a front view showing the modification of the curvature measuring device concerning a 3rd embodiment. It is a front view showing modification 2 of the curvature measuring device concerning a 1st embodiment. FIG. 4 is a perspective view showing the curvature measuring device shown in FIG. 3. It is a perspective view which shows the modification of the curvature measuring device shown in FIG.

(1st Embodiment)
A first embodiment will be described with reference to FIGS.

As shown in FIG. 1, a film forming apparatus 1 according to the first embodiment includes a chamber 2 serving as a film forming chamber for forming a film on a substrate W, and a gas (a raw material gas) supplied to the substrate W in the chamber 2. A gas supply unit 3 for supplying the substrate W, a shower plate 4 positioned above the chamber 2, a susceptor 5 for supporting the substrate W in the chamber 2, a rotating unit 6 for holding and rotating the susceptor 5, and a substrate W. , A plurality of gas discharge units 8 for discharging gas from the chamber 2, an exhaust mechanism 9 for exhausting gas from the gas discharge units 8, and a curvature (warpage amount) of the substrate W are measured. Curvature measuring device 1
0, a control unit 11 for controlling each unit, and a notification unit 12 for notifying a warning.

The chamber 2 functions as a film formation chamber (reaction chamber) in which a thin film is vapor-phase grown on a surface of a substrate W (for example, a semiconductor substrate wafer) to form an epitaxial film. The chamber 2 is formed in a box shape such as a cylindrical shape, and houses therein a substrate W to be processed and the like.

The gas supply unit 3 includes a plurality of gas storage units 3a that individually store gas, a plurality of gas pipes 3b that connect the gas storage unit 3a and the shower plate 4, and a gas supply unit that supplies the gas flowing through the gas pipes 3b. A plurality of gas valves 3c for changing the flow rate are provided. These gas valves 3
“c” is individually provided for each gas pipe 3 b and is electrically connected to the control unit 11, and its driving is controlled by the control unit.

The gas supply unit 3 supplies a source gas for growing a crystal film on the surface of the substrate W heated by the heater 7, for example, three types of gases, through the shower plate 4 to the inside of the chamber 2. For example, a metal organic chemical vapor deposition (MOCVD) method using a Si substrate as the substrate W
When a GaN (gallium nitride) epitaxial film is formed using GaN, as an example, a source gas of gallium (Ga) such as a trimethyl gallium (TMG) gas, ammonia (N
A source gas of nitrogen (N) such as H3) and a hydrogen gas as a carrier gas are used.

These three types of gases are stored in the respective gas storage sections 3a, and these gases are supplied as a raw material gas from the shower plate 4 toward the substrate W in a shower shape, and a GaN epitaxial film is formed on the substrate W. Will be formed. The type and number of gases are not particularly limited. For example, when a silicon nitride (SiC) epitaxial film is formed on the substrate W, the first, second, and third types are used. It is possible to use a source gas of carbon, a source gas of silicon, and a gas used for separating these gases, and a separation gas having low reactivity with the other two gases. is there.

The shower plate 4 is provided on the upper part of the chamber 2 and is formed in a plate shape having a predetermined thickness. The shower plate 4 has a plurality of gas supply passages 4a through which gas flows, and a large number of gas discharge holes (gas ejection holes) 4b connected to the gas supply passages 4a. The gas supply flow path 4a and the gas discharge holes 4b are formed on the substrate W in a state where each gas is separated without mixing a plurality of types (for example, first, second, and third types) of each gas. It is formed in such a structure that it can be sprayed toward the shower. For example, the gas supply channels 4a are independent of each other, and the gases are mixed in the shower plate 4 and are prevented from reacting with each other. In the shower plate 4, the gases are not necessarily supplied separately, but may be supplied as a mixture.

The shower plate 4 rectifies a gas for forming an epitaxial film and supplies the gas from each of the gas discharge holes 4b toward the surface of the substrate W in a shower shape. As a material for the shower plate 4, for example, a metal material such as stainless steel or an aluminum alloy can be used. By using such a shower plate 4, the flow of the source gas in the chamber 2 can be made uniform, and the source gas can be uniformly supplied onto the substrate W.

The susceptor 5 is provided above the rotating unit 6 and is formed in an annular shape having an opening 5a. The susceptor 5 has a structure in which a counterbore (annular concave portion) is provided on the inner peripheral side of the opening 5a, and the outer peripheral portion of the substrate W is received and supported in the counterbore. Since the susceptor 5 is exposed to a high temperature, for example, the surface of a carbon (C) material such as isotropic graphite is coated with high-heat-resistant high-purity SiC by a CVD method. As the structure of the susceptor 5, a structure in which the opening 5a is left as it is as described above is used. However, the structure is not limited to this. For example, a member for closing the opening 5a is provided, and the opening 5a is formed. It is also possible to use a closing structure.

The rotating part 6 has a cylindrical part 6a for holding the susceptor 5, and a hollow rotating body 6b serving as a rotation axis of the cylindrical part 6a. The cylindrical portion 6a has a structure in which an upper portion is opened, and the susceptor 5 is arranged on the upper portion of the cylindrical portion 6a. When the substrate W is placed on the susceptor 5, the opening 5a of the susceptor 5 is covered, and a hollow region is formed. In the rotating part 6, the susceptor 5 rotates through the cylindrical part 6a by rotating the rotating body 6b by a rotating mechanism (not shown). Therefore, the substrate W on the susceptor 5 rotates with the rotation of the susceptor 5.

Here, the space region in the chamber 2 is a first region R1, and the hollow region substantially separated from the first region R1 by the substrate W and the susceptor 5 is a second region R2. Since the first region R1 and the second region R2 are separated from each other, it is possible to prevent the surface of the substrate W from being contaminated by contaminants generated around the heater 7. Further, it is also possible to prevent the gas in the first region R1 from entering the second region R2 and coming into contact with the heater 7 arranged in the second region R2.

The heater 7 is provided in the cylindrical portion 6a, that is, in the second region R2. As the heater 7, for example, a resistance heater can be used, and the heater is configured by coating a surface of a carbon (C) material such as isotropic graphite with high heat resistant SiC. The heater 7
Power is supplied by a wiring 7a passing through a substantially cylindrical quartz shaft 6c provided in the rotating body 6b, and the substrate W is heated from the back surface. The wiring 7a is electrically connected to the control unit 11, and the power supply to the heater 7 is controlled by the control unit 11.

An elevating pin, an elevating device (both not shown), and the like are disposed as a substrate elevating mechanism inside the shaft 6c. The elevating device can raise or lower the elevating pins, and the elevating pins are used when the substrate W is carried into the chamber 2 and carried out of the chamber 2. The lifting pins support and lift the substrate W from below, and separate it from the susceptor 5.
Then, the operation is performed so that the substrate W is arranged at a predetermined position on the rotating unit 6 above the susceptor 5 so that the substrate W can be transferred to and from a transfer robot (not shown) for the substrate W. I do.

The gas discharge section 8 is a discharge hole for discharging the source gas after the reaction, and a plurality of gas discharge sections are provided below the chamber 2. These gas discharge units 8 are provided on the bottom surface of the chamber 2 and around the rotating unit 6 and are connected to an exhaust mechanism 9 for exhausting gas.

The exhaust mechanism 9 includes a plurality of gas exhaust passages 9a through which the reacted source gas flows, an exhaust valve 9b for changing the flow rate of the gas, and a vacuum pump 9c serving as a driving source for exhaust. The exhaust mechanism 9 exhausts the reacted raw material gas from the inside of the chamber 2 through each gas exhaust unit 8. The exhaust valve 9b and the vacuum pump 9c are electrically connected to the control unit 11, and the driving thereof is controlled by the control unit 11. Note that the exhaust mechanism 9 can adjust the inside of the chamber 2 to a predetermined pressure under the control of the control unit 11.

The curvature measuring device 10 is provided above the shower plate 4, and measures the curvature of the substrate W on the susceptor 5 by projecting and receiving two laser beams on the substrate W on the susceptor 5 (details). , Described below). Each laser beam is applied to each gas supply passage 4 of the shower plate 4.
a, a portion having a light transmitting property, ie, a window of the chamber 2 (a window for passing a laser beam)
Light is emitted and received through The curvature measuring device 10 is electrically connected to the control unit 11 and passes the measured curvature (curvature information) to the control unit 11.

As the shape of the window of the chamber 2, various shapes such as a slit shape, a rectangular shape, and a circular shape can be used, and the size of the window is such that it can project and receive laser light. It is. As a material of the window, for example, a light-transmitting material such as quartz glass can be used.

The control unit 11 includes a microcomputer for centrally controlling each unit, and a storage unit (not shown) for storing film formation processing information regarding the film formation processing, various programs, and the like. The control unit 11 controls the gas supply unit 3, the rotation mechanism of the rotation unit 6, the exhaust mechanism 9, and the like based on the film formation processing information and various programs, and rotates the susceptor that rotates according to the rotation of the rotation unit 6. Control of gas supply for supplying various gases from the gas supply unit 3 via the shower plate 4 to the surface of the substrate W on the substrate 5 and heating of the substrate W by the heater 7 are performed. In the control of the gas supply unit 3, the operation of each gas valve 3 c of the gas supply unit 3 is controlled, and three types of gas supply, for example, timings and periods for supplying three types of gases are adjusted. Is possible.

In addition, the control unit 11 determines whether the curvature measured by the curvature measuring device 10 has reached a predetermined set value, and determines that the curvature measured by the curvature measuring device 10 has reached a predetermined set value. The film processing is stopped, and a notification instruction is output to the notification unit 12. The set value is set in advance by a user or the like via an input unit (for example, an input device such as a keyboard or a mouse), and can be changed as needed.

When the notification unit 12 receives the notification instruction from the control unit 11, that is, when the curvature measured by the curvature measuring device 10 reaches a predetermined set value, the user is informed that there is a problem with the warpage of the substrate W (warning). ). As the notification unit 12, for example, various notification units such as an alarm device such as a lamp and a buzzer, a display unit for displaying characters, and a voice output unit for outputting a voice can be used.

In the film forming apparatus 1 having such a configuration, the substrate W is rotated by the rotation of the rotating unit 6, and the substrate W is heated by the heater 7. Further, three types of source gases are introduced into the chamber 2 by the shower plate 4, and the three types of source gases are respectively supplied in a shower shape toward the surface of the substrate W, and the epitaxial film is vapor-phased on the substrate W such as a wafer. It grows and forms a film. The shower plate 4 separates the substrates W in the chamber 2 without mixing the three gases.
To supply. In this film forming apparatus 1, a plurality of types of gases, for example, first, second and third types of gases are used to form an epitaxial film, but the types of gases are limited to three types. For example, two types or more types than three types may be used.

The transfer of the substrate W into the chamber 2 or the transfer of the substrate W out of the chamber 2 can be performed using a transfer robot (not shown). In this case, the above-described substrate lifting mechanism can be used. For example, when carrying out the substrate W, the substrate W is lifted by the substrate lifting mechanism and separated from the susceptor 5. Next, the substrate W is delivered to the transfer robot, and is carried out of the chamber 2. When the substrate W is loaded, the substrate W is received from the transfer robot, and the substrate W is lowered by the substrate lifting mechanism, and the substrate W is placed on the susceptor 5.

Next, the above-described curvature measuring device 10 will be described in detail with reference to FIGS. FIGS. 2 to 4 show schematic structures of the curvature measuring device 10 using schematic diagrams of optical components. Although the separation distance between the curvature measuring device 10 and the substrate W is shown to be short, in actuality, Is 2
The distance is about 0 to 50 cm, and the laser light passes through the window of the chamber 2. Although the direction of the laser beam reflected by the polarizing beam splitter is shown to be bent at a substantially right angle, this angle does not need to be particularly near the right angle in some cases.

As shown in FIG. 2, the curvature measuring device 10 includes an irradiation unit 10 a that causes two laser beams L <b> 1 and L <b> 2 to be incident on a substrate W to be measured in parallel and a laser beam L <b> 1 and L <b> 2. An optical filter 10b that cuts light other than the wavelength, a condenser lens 10c that collects the two laser lights L1 and L2, and a course change that separates the two laser lights L1 and L2 mirror-reflected by the substrate W. Part 10d and the first laser light L of the two separated laser lights L1 and L2
One one-dimensional first position detecting element 10e for detecting the incident position of the first one, and one-dimensional second position detecting element 10e for detecting the incident position of the second laser light L2 of the two separated laser lights L1 and L2. The curvature (warpage) of the substrate W is calculated using the position detection element 10f and the incident positions of the laser beams L1 and L2 detected by the first position detection element 10e and the second position detection element 10f. And a calculation unit 10g.

The irradiation unit 10a causes the first laser light L1 and the second laser light L2 having different polarization directions, that is, different polarization components (polarization planes) to be incident on the substrate W in a state where they are parallel to each other. For example, the irradiation unit 10a includes a laser light emitting unit (light emitting unit) 21, a polarizing beam splitter (first polarizing beam splitter) 22, and a mirror (reflecting unit) 23 for emitting laser light. The irradiating section 10a separates the laser light emitted from the laser light emitting section 21 into an S-polarized component (S-polarized light) and a P-polarized component (P-polarized light) by a polarization beam splitter 22, and outputs the S-polarized component The first laser beam L1) is directly incident on the substrate W, and the mirror 23 reflects the laser beam of the P-polarized component (second laser beam L2) so as to be parallel to the laser beam of the S-polarized component. Incident on The traveling directions of the laser beams L1 and L2 do not necessarily have to be strictly parallel. As described above, the polarization component (polarization direction) includes, for example, an S-polarization component and a P-polarization component perpendicular to the traveling direction of light, and the S-polarization component and the P-polarization component are components orthogonal to each other. At this time, the polarization components (polarization directions) do not necessarily need to be orthogonal to each other, but are preferably at least 70 degrees and at most 90 degrees for more accurate separation.

Here, the polarizing beam splitter is an optical component formed by bonding two prisms on one bonding surface, and by forming a multilayer film of a dielectric material on the bonding surface in advance, the bonding is performed according to the polarization direction. It has the function of transmitting or reflecting light on the surface. By appropriately designing the structure of the multilayer film formed on the bonding surface, it has a function of reflecting P-polarized light on the bonding surface and transmitting S-polarized light, or conversely, reflecting S-polarized light on the bonding surface and transmitting P-polarized light. Functional ones can be made. For simplicity, the former polarization beam splitter is called a P-polarization reflection type or S-polarization transmission type, and the latter polarization beam splitter is called an S-polarization reflection type or P-polarization transmission type. These polarizing beam splitters having different functions have their respective characteristics and can be used properly. The polarization beam splitter 22 shown in FIG. 2 for splitting the laser beam into two is an S-polarized light transmission type, and a polarized beam for splitting the two laser beams reflected from the object to be measured (substrate W) by polarized light. The splitter (the course changing unit 10d) is an S-polarized reflection type. FIG. 3 shows a case where the present embodiment having the configuration of FIG. 2 is configured using only a P-polarized light transmission type polarization beam splitter. References regarding the S-polarized light transmission type polarizing beam splitter include “WO9707418 (WO / 1997/007418)” or “Li Li and JA Dobr”.
owolski, "High-performance thin-film polarizing beam splitter operating at angle
s greater than the critical angle ", Applied Optics, Vol. 39, No. 16, pp. 2754-71
].

The incident position of the laser beams L1 and L2 with respect to the substrate W is, for example, near the center of the substrate W, and the incident angle A1 thereof is desirably at least 20 degrees or less (details will be described later). Further, as the laser light, a wavelength of 700 nm or less, more preferably 600 nm or less (for example, 532 nm), in which the sensitivity of the silicon detection system is high and the influence of heat radiation is small, is avoided by avoiding the influence of light emission of the substrate W that glows red. It is desirable to use the laser light of

The optical filter 10b is provided between the substrate W and the course changing unit 10d and is provided with the first laser light L1.
And the second laser light L2 are provided on an optical path that travels in parallel, and cut (remove) light other than the wavelengths of the first laser light L1 and the second laser light L2. For example, a monochromatic filter can be used as the optical filter 10b. By providing the optical filter 10b, light having a wavelength other than the laser beams L1 and L2 (green in the above example) is prevented from being incident on the position detection elements 10e and 10f. The position detection accuracy can be improved by avoiding the influence of the light emission.

In addition, as the one-dimensional position detecting element 10e or 10f, for example, a semiconductor position detecting element (
PSD) is used. PSD is the center of gravity of the distribution of the incident laser light (the light amount of the spot) (
Position), and the center of gravity is output as two electric signals (analog signals). PSDs are sensitive to light in the visible light range. In the film forming apparatus 1, the substrate W is red-hot, that is, emits light on the red side. If the substrate W only heats up red, the intensity of the laser light is overwhelmingly strong. Therefore, no problem occurs if at least a green laser light away from red is used. However, when a film is formed in the film forming apparatus 1, there occurs a timing at which the laser light is hardly reflected by interference between the film and the laser light. At this timing, the intensity of the red heat exceeds the intensity of the reflected laser beam, so that the position detecting element 10
On e or 10f, the position of the laser beam reflected from the measurement object (substrate W) may not be measured accurately or at all. To suppress this, it is desirable to provide an optical filter 10b that does not transmit light other than the wavelength of the laser light used in the present embodiment. In addition, as the position detecting element 10e or 10f, in addition to the PSD, a solid-state imaging device (CCD or CM) is used.
OS, etc.) can also be used.

In addition, in order to eliminate the effect of the interference caused by the film formed on the object to be measured, it is also effective to use laser light having a wavelength that the film to be formed absorbs as the laser light in the present embodiment. . More specifically, a laser beam having higher energy than the band gap of a film to be formed can be given. When the film to be formed absorbs the laser beam used in the present embodiment, the interference effect decreases as the film becomes thicker, and the interference effect does not appear at a certain thickness or more. For example, when a GaN film is formed, GaN has an absorption edge in the ultraviolet region (365 nm) at room temperature, but has a small band gap at a temperature of 700 ° C. or more and absorbs light in the blue-violet region. Therefore, when GaN is grown at a temperature of 700 ° C. or higher, the effect of GaN interference can be reduced by using, for example, 405 nm laser light in the present embodiment.

The condenser lens 10c is provided between the substrate W and the course changing part 10d and on an optical path where the first laser light L1 and the second laser light L2 travel in parallel. This condenser lens 10
c focuses the first laser beam L1 on the element surface (light receiving surface) of the first position detection element 10e in a direction (short direction) perpendicular to the element row direction of the first position detection element 10e; The second laser light L2 is applied to the second position detecting element 10f on the element surface (light receiving surface) of the second position detecting element 10f.
The light is condensed in the direction (transverse direction) perpendicular to the element row direction of f. A semi-cylindrical lens can be used as the condenser lens 10c.

Here, as shown in FIG. 4 (side view of FIG. 2), when the substrate W is tilted due to vibration or the like, the substrate W
The second laser light L <b> 2 reflected by the laser beam deflects in a fan shape from a point (incident point) incident on the substrate W. Although not shown in FIG. 4 for simplification of the drawing, the first laser light L1 also has a fan shape. For this reason, the second laser light L2 reflected by the substrate W is added to the second laser light L2 so that the first laser light L1 reflected by the substrate W does not deviate from the first position detecting element 10e. In order to collect light so as not to deviate from the position detecting element 10f, an appropriate lens is provided as the condenser lens 10c. This makes it possible to collect the first laser light L1 and the second laser light L2 that have swung in a fan shape due to the inclination of the substrate W again at one point.
At this time, if a simple circular lens is used, there is a case where even the displacement information due to the warpage of the substrate W is lost. Therefore, the warp information direction, that is, each position detecting element 10e and 10f
A semi-cylindrical lens is used as the condenser lens 10c so as not to condense the light displacement in the longitudinal direction.

As described above, the amount of deflection in the short direction of each of the position detection elements 10e and 10f is determined by the condensing lens 10c.
Is no longer a problem. On the other hand, those longitudinal deflections are the two position detecting elements 1
There is no problem because the difference between the incident positions of 0e and 10f is canceled by taking the difference. From these facts, it is possible to maintain the S / N. It should be noted that an excessively large deflection such that the laser beam deviates from the two position detection elements 10e and 10f even by such a method is a problem of the apparatus itself of the film forming apparatus 1 (for example, abnormal vibration, assembly accuracy, etc.). ) Or when the substrate W comes off the counterbore 5a of the susceptor 5. Conversely, by appropriately monitoring the signal from the curvature measuring device, the above-described abnormality can be quickly found.

The course changing unit 10d includes the first laser light L1 and the second laser light L1 that are specularly reflected by the surface of the substrate W.
Are separated, and their traveling directions are changed to greatly different directions. For example, a polarization beam splitter (a second polarization beam splitter) can be used as the course changing unit 10d. The traveling directions of the diverted first laser light L1 and second laser light L2 are such that the first laser light L1 can be detected by the first position detection element 10e, and the second position detection is performed. The range is set so that the second laser beam L2 can be detected by the element 10f. In addition, it is also possible to add an optical component such as a mirror between the course changing unit 10d and the position detecting element 10e or 10f to change the installation position of the position detecting element 10e or 10f.

The first position detection element 10e is a first laser beam L1 separated by the course changing unit 10d.
And a one-dimensional position detecting element that receives the first laser light L1 of the second laser light L2 and detects the incident position (light receiving position) thereof. The first position detecting element 10e has an element surface (
The normal direction of the (light receiving surface) is provided to be inclined within a range of 10 to 20 degrees from the optical axis of the first laser beam L1.

The second position detecting element 10f is provided with the first laser beam L1 separated by the course changing unit 10d.
And a one-dimensional position detecting element that receives the second laser light L2 of the second laser light L2 and detects the incident position (light receiving position) thereof. Like the first position detecting element 10e, the second position detecting element 10f has a normal direction of the element surface (light receiving surface) within a range of 10 to 20 degrees from the optical axis of the second laser beam L2. It is provided to be inclined.

In this manner, the normal direction of the detection surface of the position detectors (the first position detection element 10e and the second position detection element 10f) is deliberately inclined with respect to the direction of the incident laser light so that the light is reflected from the position detector. It is possible to prevent the returned laser light from returning to the above optical system (return light). The returned light acts as noise on the originally required reflected light from the measurement object. By tilting the position detector as described above, the reflected light from the position detecting element 10e or 10f is prevented from entering the course changing unit 10d, and the position detection accuracy is reduced due to the adverse effect of the reflected light (return light). Can be suppressed.

The calculating unit 10g calculates a substrate using the incident position of the first laser light L1 detected by the first position detecting element 10e and the incident position of the second laser light L2 detected by the second position detecting element 10f. The curvature (warpage amount) of W is calculated. For example, the calculating unit 10g calculates the displacement amount of the incident position of the first laser light L1 detected by the first position detecting element 10e and the second laser light L2 detected by the second position detecting element 10f. A difference between the displacement amount of the incident position and the calculated difference is correlated with the respective optical path lengths of the first laser light L1 and the second laser light L2, and the curvature change amount of the substrate W is calculated. The curvature before the displacement can be converted into an absolute value of the radius of curvature by using a calibration mirror, a substrate without deformation, or the like as a reference.

As a predetermined relational expression indicating the correlation, as an example, the displacement amount on the position detectors (the first position detection element 10e and the second position detection element 10f) corresponding to each of the laser beams L1 and L2 is X1. And X2, the respective optical path lengths of the laser beams L1 and L2 are Y1 and Y2, and the amount of curvature change is Z1, the relational expression of (X1 + X2) / 2 = w × Y × Z1 is given. Here, w is the distance between the irradiation positions of the two laser beams on the object to be measured. In addition,
It is assumed that Y1 and Y2 are approximately equal, and Y is the same. The signs of X1 and X2 are such that the displacements of the two laser beams in the center direction are the same.

Here, it is not realistic to measure w and Y exactly, but on the other hand, since there is no significant change at the time of measurement, the total amount of displacement is expressed as “Xtotal = C × Z1” (Xtotal = X1 + X2). In a simple relationship in which the curvature is proportional to (ie, the change in the geometric distance between the two laser beams), C can be determined and applied by the calibration mirrors (two types) having a known radius of curvature. One of the two types has a radius of curvature as infinite as possible (that is, a plane), and the other preferably has the smallest possible radius of curvature. If possible, it is preferable to measure those having an intermediate radius of curvature and confirm that linearity (when a calibration curve is prepared for Z1) is established in the measurement range.

Further, it is preferable that the calculation unit 10g captures signals from the position detection elements 10e and 10f at a predetermined timing. For example, the calculation unit 10g captures the phase signal of the periodic motion accompanying the substrate W and simultaneously captures the signals from the position detection elements 10e and 10f,
The curvature is calculated using only the position signal in an arbitrary phase range of the periodic motion. For example, when the periodic motion is a rotational motion, the timing of capturing a signal is set as the timing of each rotation of the motor of the rotation mechanism (Z-phase pulse of the motor), and each position detection element is synchronized with the rotation of the motor. Capture signals from 10e and 10f. The position signal may be information of any one point, may be an average value in an arbitrary range, and preferably integrates them.
When these are difficult, it is recommended to take in all the information for a plurality of cycles and take the average.

Next, a laser beam interval on the surface of the substrate W (the first laser beam L1 and the second laser beam L2
Will be described with reference to FIG. Although actually more complicated than FIG. 5, the model is simplified to estimate the order of the displacement.

As shown in FIG. 5, a mirror surface having a radius of curvature R (m) is assumed, and a line segment (radius) extending from a tangent to the mirror surface and passing through the center of the mirror surface is H. The light beam is incident on the mirror surface in parallel with the line segment H, and is reflected inside the mirror surface. As long as the curvature does not become very large, the point where the reflected light beam intersects with the line segment H is approximated as the midpoint of the deformation (R / 2), and the displacement amount observation point in the curvature measurement device 10 is the height in FIG. It is approximated as L, the amount of displacement observed when the curvature of the reflected light beam changes is approximated as dZ, and the reflection point of the incident light beam is approximated as being at the same height as the lowest point of the circle.

Here, assuming that a straight line distance between the straight line H and the incident light beam is w (m), dZ is dZ = w−Z =
w− (R / 2−L) × tan (2α), and tan (2α) is tan (2α) by approximation.
) = 2α = 2w / R, so that dZ = w− (R / 2−L) × 2w / R = 2wL / R.

As an example, considering the film formation state of GaN based on a change in the radius of curvature of about 100 (m), the resolution of the change in curvature is 100 (m) at the worst, and 500 (m) in reality. In this case, 1000 (m) is preferable. On the other hand, as described above, it is desirable that the distance between the substrate W and each of the position detection elements 10e and 10f is long. However, in actuality, disturbance (air fluctuation) due to convection of air in the optical path and installation in the apparatus housing are also required. 20 to 20
A value of 50 cm is appropriate. Here, the radius of curvature (R) is 500 m or more, and the distance (L)
Is 30 cm, the above equation becomes dZ = 0.012 w.

However, the displacement dZ has a lower limit due to the performance of the light receiving element. For example, in a CCD, the element pitch is about 1 μm unless it is very expensive and high performance. Also, since PSD is an analog measurement, the limitation of the light receiving element itself is not clear, but the performance of a general-purpose logger that captures the signal is within a reasonable range of 10 nm to 0.1 μm. Even if is used, it is difficult to recognize a change on the order of nm due to a disturbance such as air. As a result, it is practical in most cases if a displacement of about 1 μm can be practically identified. Therefore, from the above formula, first, it is preferable that w is 1 mm or more.

On the other hand, on the side where the curvature is large and the amount of displacement is large, the laser beam interval must be limited to the light receiving range of the light receiving element and the laser interval so as not to protrude from the optical element related to the light collecting system. The radius of curvature may be less than 1 m, and it is better to assume the range of measurable up to about R = 0.5 m. In this case, dZ = 1.2w in the above equation. A relatively general-purpose C that is easy to obtain
CDs and PSDs have a light receiving size of about 10 mm square to 20 mm square, and w may be 8 to 16 mm so that the displacement amount falls within the light receiving range. However, for the optical element up to the light receiving element, for example, if a small one is selected in order to reduce the cost, the optical element is usually limited to 10 mm square. That is, the displacement width is 1 no matter how large
It is required to be less than 0 mm. For this reason, it is desirable that w is 8 mm or less, preferably about 4 mm or less in view of a margin for positive and negative optical path changes.

As described above, the straight line distance (laser interval) w between the straight line H and the incident light beam is 8 mm or less or 4 m.
m and preferably 1 mm or more as described above.
Therefore, it is preferable that w is within a range of 1 mm ≦ w ≦ 8 mm, and further, 1
More preferably, it is within the range of mm ≦ w ≦ 4 mm.

When two optical paths overlap on the surface of the substrate W (that is, when they are incident on the same point), the inclination of the reflection point is the same for both optical paths. That is, both are inclined by the same amount in the same direction. In the two laser systems, since the warpage (curvature) is obtained from the difference between the two inclinations, detection cannot be performed in principle if both are the same, and the incident point needs to be shifted even slightly. On the other hand, the greater the distance between the incident points, the greater the difference between the two inclinations and the higher the sensitivity. However, it is difficult to provide a large window in the chamber 2 in the film forming apparatus 1. For this reason, it is desirable to set the laser beam interval in the range described above,
It is also possible to set the laser beam interval outside the above-mentioned range according to various conditions (for example, a window size that can be secured).

Next, the incident angle of the laser beam to the surface of the substrate W (the individual incident angle of the first laser beam L1 and the second laser beam L2) will be described with reference to FIG.

FIG. 6 shows the dependency of the reflectance on the incident angle (the relationship between the incident angle and the reflectance) when the substrate W is quartz. Graph B1 is a graph when the incident light is S-polarized light, and graph B2 is a graph when the incident light is P-polarized light. From these graphs B1 and B2, for S-polarized light and P-polarized light traveling parallel to the incident surface, when the incident angle is 0 degree, the reflectance is the same, and the incident angle is 10 degrees or 20 degrees. It is almost the same to the extent. Therefore, in order to make the reflectances of the S-polarized light and the P-polarized light substantially the same, it is desirable that the light incident angle A1 (see FIG. 2) be at least 20 degrees or less.

As described above, such a curvature measuring device 10 is used in the above-described step of forming an epitaxial film.
The warpage of the substrate W is monitored. In this warpage monitoring, the first laser light L having different polarization directions is used.
The first and second laser beams L2 are irradiated by the irradiation unit 10a and are incident on the surface of the substrate W in parallel. Next, the first laser light L1 and the second laser light L2 specularly reflected by the substrate W pass through the optical filter 10b in parallel and further pass through the condenser lens 10c.
It is separated by the course changing unit 10d. The separated first laser light L1 and second laser light L2 are condensed in the lateral direction of the first position detecting element 10e and the second position detecting element 10f by the action of the condensing lens 10c. Then, among the separated laser beams L1 and L2, the first laser beam L1 is detected by the first position detecting element 10e, and the second laser beam L2 is detected by the second position detecting element 10f.

After that, the incident positions of the first laser light L1 and the second laser light L2 are calculated by the calculation unit 1.
0 g is used to calculate the curvature (the amount of warpage) of the substrate W. For example, the first laser light L
The difference between the amount of displacement of the incident position of No. 1 and the amount of displacement of the incident position of the second laser beam L2 is calculated, and the amount of curvature change (curvature) of the substrate W is calculated from the correlation between the difference and each optical path length. You. When the calculated curvature is input to the control unit 11, the control unit 11 determines whether the input curvature is greater than a predetermined set value, and determines whether the curvature measured by the curvature measurement device 10 is a predetermined value. If it is determined that the value is larger than the set value, processing such as stopping the film forming process and outputting a notification instruction to the notification unit 12 can be performed. When the notification unit 12 receives the notification instruction from the control unit 11, the notification unit 12 can perform processing such as notifying the user that there is a problem with the warpage of the substrate W (warning).

Here, in the conventional two-point collective CCD method, when the warpage is large as described above, the two points may coincide with each other, and the distance between the two points no longer exists. Will exist. On the other hand, according to the present embodiment, no matter where the two laser beams L1 and L2 overlap, the two laser beams L1 and L2 are forcibly separated by their polarization and the course changing unit 10d. Further, it is calculated how much the position of each of the laser beams L1 and L2 has shifted from the original position, and the change in the interval is read only by subtraction. Therefore, there is no unmeasurable region as in the conventional two-point collective CCD system, and the SN ratio (S / N) in the vicinity does not decrease. In addition, in the conventional two-point collective CCD method, optical path adjustment (setting) must be performed to avoid an unmeasurable area. However, according to the present embodiment, the restriction is eliminated, and the robustness of the adjustment is reduced. Get higher.

The laser beams L1 and L2 of the curvature measuring device 10 pass through the window of the chamber 2,
The window of the chamber 2 tends to tilt due to various factors. These various factors include, for example, deformation of the chamber 2 due to heat and displacement due to vibration. Further, the substrate W measured by the curvature measuring device 10 generates periodic vibration due to rotation. Even if such a window tilt or periodic vibration of the substrate W occurs, the first laser light L
1 so as not to deviate from the first position detecting element 10e.
Light is collected so that 2 does not deviate from the second position detecting element 10f. That is,
Since the first laser light L1 and the second laser light L2, which oscillate in a fan shape due to the inclination of the window and the periodic vibration of the substrate W, are collected again at one point, the curvature is caused by the inclination of the window and the periodic vibration of the substrate W. A decrease in measurement accuracy can be suppressed.

As described above, according to the first embodiment, the first laser light L1 and the second laser light L2 having different polarization directions are incident on the substrate W in parallel, and are specularly reflected by the substrate W. The courses of the first laser light L1 and the second laser light L2 are changed by the course changing unit 10d so as not to be mixed, and the first laser light L1 and the second laser light L2 whose courses are changed are further changed. Each is detected by the first position detecting element 10e and the second position detecting element 10f. Therefore, unlike the case of using the conventional two-point collective CCD method, the two points on the element surface of the CCD do not coincide with each other, and even if the two laser beams L1 and L2 overlap, they are separated. Are detected by the two position detecting elements 10e and 10f, respectively. Accordingly, unlike the conventional two-point collective CCD method, measurement is not impossible, and the deterioration of the S / N ratio (S / N) is suppressed even when the warpage is large or the distance between the two points is narrow. It becomes possible. Therefore, it is possible to suppress the curvature measurement from being impossible and improve the curvature measurement accuracy.

(Second embodiment)
A second embodiment will be described with reference to FIG. In the second embodiment, differences from the first embodiment (component arrangement of the curvature measuring device 10) will be described, and other description will be omitted. FIG. 7 shows a schematic structure of the curvature measuring device 10 using schematic diagrams of optical components, similarly to FIGS. 2 to 4 described above, and the distance between the curvature measuring device 10 and the substrate W is large. Although shown briefly, the actual separation distance is about 20 to 50 cm, and the laser light passes through the window of the chamber 2. Although the direction of the laser beam reflected by the polarizing beam splitter is shown to be bent at a substantially right angle, this angle does not need to be particularly near the right angle in some cases.

As shown in FIG. 7, the irradiation unit 10a of the curvature measuring device 10 according to the second embodiment includes a laser light emitting unit (light emitting unit) 21 that emits laser light, and the first laser light. L1 (
A polarization beam splitter 22 for separating the laser beam into S-polarized light and second laser light L2 (P-polarized light), and a mirror 23 are provided. The polarization beam splitter 22 is provided on an optical path between the laser light emitting unit 21 and the surface of the substrate W, and the mirror 23 transmits the first laser light L1 separated by the polarization beam splitter 22 to the substrate W. It is provided at a position where it reflects toward the surface.

The irradiating section 10a separates the laser light emitted from the laser light emitting section 21 into a first laser light L1 and a second laser light L2 by a polarization beam splitter 22, and converts the second laser light L2 into the substrate W as it is. And the first laser light L1 is converted by the mirror 23 into the second laser light L2.
Is reflected so as to be parallel to the surface of the substrate W and is incident on the surface of the substrate W.

Note that the optical filter 10b, the condenser lens 10c, the course changing unit 10d, and the second position detecting element 10f are provided substantially on the normal line of the substrate W, and the first position detecting element 10e is advanced by the course changing unit 10d. It is provided at a position where the first laser light L1 whose direction has been changed can be detected. The two beam splitters 22 and 10d used in the present embodiment having the configuration shown in FIG. 7 are both P-polarization transmission type polarization beam splitters.

In the curvature measuring device 10 having such a configuration, the first laser light L1 and the second laser light L2
, The four optical paths, which are the sum of the incident optical path to the substrate W and the reflected optical path from the substrate W, are adjusted to be substantially in the same plane, and further adjusted to a position where the reflected optical path is sandwiched between the incident optical paths. Accordingly, in all the optical paths of the incident optical path and the reflected optical path passing through the window of the chamber 2, the separation distance between the optical paths located on the outer periphery thereof can be reduced. For this reason, the window of the chamber 2 through which each of the laser beams L1 and L2 passes can be reduced, and as a result, the detection position accuracy can be prevented from lowering due to the inclination of the window due to heat or the like.

As described above, according to the second embodiment, it is possible to obtain the same effects as those of the above-described first embodiment, and it is possible to suppress the curvature measurement from being disabled and improve the curvature measurement accuracy. it can. Further, since the window of the chamber 2 through which the laser beams L1 and L2 pass can be reduced, it is possible to suppress a decrease in the detection position accuracy due to the inclination of the window due to heat or the like.

(Supplement to the first or second embodiment described above)
Here, some of the various features of the first or second embodiment will be enumerated.

The angles of incidence of the laser light on the substrate W, that is, the first laser light L1 and the second laser light L2 are at least 20 degrees or less (see FIG. 2). Thereby, the first laser light L1 and the second
When the laser light L2 is S-polarized light and P-polarized light, it is possible to make the reflectances of the two substantially the same (see FIG. 6), so that the position detection accuracy can be improved.

When the path changing unit 10d is removed (in a state), the respective optical paths of the first laser light L1 and the second laser light L2 are the element surfaces (light receiving surfaces) of the second position detecting element 10f. ) Are adjusted so as to intersect (see FIG. 2). Thereby, each of the laser beams L1 and L
Since the distance between the two optical paths can be reduced, the course changing unit 10d can be reduced in size. Note that it is desirable that the above-mentioned intersection position be the center of the second position detection element 10f in the longitudinal direction. In this manner, the position detector 10 is caused by the periodic vibration of the substrate W or the like.
Even if the irradiation position of the laser beam L1 or L2 moves on the light receiving surface of f or 10e, the possibility that this irradiation position extremely becomes the end of the light receiving surface or deviates from the light receiving surface is reduced, and the position detection is performed. A decrease in accuracy can be suppressed.

The light receiving surface (first light receiving surface) of the first position detecting element 10e is inclined at least 10 degrees from the optical axis of the first laser light L1 (the optical axis of the incident light). Similarly, the second position detecting element 1
The light receiving surface at 0f (the second light receiving surface) is also inclined at least 10 degrees from the optical axis of the second laser light L2 (the optical axis of the incident light). Accordingly, it is possible to prevent the reflected light from the position detecting element 10e or 10f from being incident on the course changing unit 10d, so that it is possible to suppress a decrease in the position detection accuracy due to the adverse effect of the reflected light.

In addition, an optical filter 10b that does not transmit wavelengths other than the wavelengths near the wavelengths of the first laser light L1 and the second laser light L2 is provided on the optical path from the substrate W to the course changing unit 10d.
This suppresses light having a wavelength other than the wavelength (for example, green) near each of the laser beams L1 and L2 from being incident on the position detection elements 10e and 10f. Avoidance can improve the position detection accuracy.

In addition, a phase signal of a periodic motion accompanying the substrate W is taken in, and each position detecting element 1
The signals from 0e and 10f are fetched, and the curvature is calculated using only the position signal at an arbitrary phase of the periodic motion. For example, when the periodic motion is a rotational motion, the timing of taking in the signal is the timing of each rotation of the motor of the rotation mechanism (Z-phase pulse of the motor), and each position detecting element is synchronized with the rotation of the motor. Capture signals from 10e and 10f. This makes it possible to read and use signals at a timing synchronized with the movement even when there is vibration due to the periodic movement, etc., and to prevent the position detection accuracy from deteriorating due to the periodic vibration. Thus, the position detection accuracy can be improved as compared with a case where a signal is read and used at a timing not synchronized with the periodic movement.

One or both of the one-dimensional position detecting elements 10e and 10f are semiconductor position detecting elements (PSDs) that output the center of gravity of the distribution of the incident laser light as two electric signals. Alternatively, one or both of the one-dimensional position detection elements 10e and 10f are solid-state imaging devices (for example, CCDs). Here, in the conventional two-point collective CCD method, a distance between two points is determined by complicated image processing, so that a high-speed computer is required, and the cost is increased. On the other hand, if the processing speed is sacrificed in order to suppress the cost, the performance of the device will be reduced. In the case of using the PSD, image processing is not required, an analog signal is read for each PSD, and simple calculations such as four arithmetic operations may be performed, thereby suppressing an increase in cost and a decrease in apparatus performance. In addition, even when a CCD is used, the incident position can be grasped by simple image processing as compared with two-dimensional image processing, and an increase in cost and a decrease in device performance can be suppressed.

In the second embodiment, all four optical paths of the two laser beams L1 and L2, which are the optical path incident on the substrate W and the optical path reflected from the substrate W, are adjusted to be substantially in the same plane. The reflected light path is adjusted to a position sandwiched between the incident light paths. Accordingly, in all the optical paths of the incident optical path and the reflected optical path passing through the window of the chamber 2, the separation distance between the optical paths located on the outer periphery thereof can be reduced. For this reason, the window of the chamber 2 through which each of the laser beams L1 and L2 passes can be reduced, and as a result, the detection position accuracy can be prevented from lowering due to the inclination of the window due to heat or the like.

(Third embodiment)
A third embodiment will be described with reference to FIG. In the third embodiment, differences from the first embodiment (part arrangement and configuration of the curvature measuring device 10) will be described, and other description will be omitted. FIG. 8 shows a schematic structure of the curvature measuring device 10 using a schematic diagram of the optical component, and the distance between the curvature measuring device 10 and the substrate W is similar to that of FIGS. 2 to 4 described above. Although shown briefly, the actual separation distance is about 20 to 50 cm, and the laser light passes through the window of the chamber 2. Although the direction of the laser beam reflected by the polarizing beam splitter is shown to be bent at a substantially right angle, this angle does not need to be particularly near the right angle in some cases.

As shown in FIG. 8, the curvature measuring device 10 according to the third embodiment is different from the first embodiment (further the second embodiment) in that the incident light perpendicular to the surface of the substrate W which is the object to be measured. And the reflected light are used to measure the curvature (the incident angle of the laser light is 90 degrees, and the incident light and the reflected light have the same optical axis).

The curvature measuring device 10 includes a 部 wavelength plate 10h through which two laser beams L1 and L2 pass, in addition to an irradiation unit 10a, a first position detection element 10e, a second position detection element 10f, and a calculation unit 10g. And the first of the two laser beams L1 and L2 mirror-reflected by the surface of the substrate W.
And a polarization beam splitter 10i that reflects the laser beam L1. This polarization beam splitter 10i is provided instead of the course changing unit 10d according to the first embodiment.

The irradiation unit 10a divides the laser light into a first laser light L1 (P-polarized light) and a second laser light L2 (S-polarized light). A polarization beam splitter 22 and a mirror 23 that reflects the second laser light L2 are provided.

The polarizing beam splitter (first polarizing beam splitter) 22 is provided between the laser light emitting unit 21 and the surface of the substrate W, that is, the first laser light L1 emitted from the laser light emitting unit 21 is applied to the surface of the substrate W. It is provided on a vertically incident optical path. This polarization beam splitter 22
Is one that substantially transmits P-polarized light and substantially reflects S-polarized light.
Bend over).

The mirror 23 reflects the second laser light L2 (S-polarized light) separated by the polarization beam splitter 22 toward the surface of the substrate W while making the second laser light L2 (S-polarized light) parallel to the first laser light L1 (P-polarized light). The second laser beam L2 that has been specularly reflected by the surface of W and passed through the quarter-wave plate 10h
Functions as a reflection part that reflects (P-polarized light) (S-polarized light and P-polarized light are bent by, for example, 90 degrees)
.

The first position detection element 10e detects an incident position of the first laser light L1 which is specularly reflected by the surface of the substrate W and reflected by the polarization beam splitter 10i. Further, the second position detecting element 10 f is mirror-reflected by the surface of the substrate W and is reflected by the mirror 23.
The incident position of the laser beam L2 is detected. The first position detecting element 10e and the second position detecting element 10f are arranged, for example, on the same straight line, but are not limited to this.

The 波長 wavelength plate 10 h includes an optical path where the first laser light L1 is perpendicularly incident on the surface of the substrate W and an optical path where the second laser light L2 is incident on the surface of the substrate W in parallel with the first laser light L1. Are provided on both optical paths. For this reason, the quarter-wave plate 10h is provided with a first laser beam L1 which is perpendicularly incident on the surface of the substrate W and a second laser beam L2 which is incident on the surface of the substrate W in parallel with the first laser beam L1. Is passed, and the first laser light L1 and the second laser light L2, which are specularly reflected by the surface of the substrate W, pass through.

Each of the laser beams L1 and L2 has a property that the polarization direction changes by 90 degrees when each of the laser beams L1 and L2 passes through the quarter-wave plate 10h twice (the laser beam becomes circularly polarized light once passed). Therefore, when P-polarized light passes through the quarter-wave plate 10h twice, the polarization direction changes by 90 degrees to become S-polarized light. Conversely, when S-polarized light passes through the quarter-wave plate 10h twice, the polarization direction changes. It changes by 90 degrees and becomes P-polarized light. Further, since the circularly polarized light is obtained by shifting the optical axis of the quarter-wave plate by 45 degrees with respect to the polarization plane of the linearly polarized light, the first laser light L1 and the second laser light L2 having the orthogonal polarization directions are obtained. By adjusting the optical axis in the middle of the polarization direction of the laser beam L2, the two laser beams L1 and L2 are adjusted.
Can be given a symmetric condition.

The polarization beam splitter (second polarization beam splitter) 10i is a first laser beam L1.
Is provided on an optical path perpendicularly incident on the surface of the substrate W, and directs the first laser beam L1 (S-polarized light) vertically mirror-reflected by the surface of the substrate W to the first position detecting element 10e. reflect. The polarization beam splitter 10i substantially transmits P-polarized light and substantially reflects S-polarized light (
Only the S-polarized light is bent, for example, by 90 degrees).

In such a curvature measuring device 10, the substrate W
Monitor for warpage. In the warpage monitoring, when the laser light is emitted by the laser light emitting unit 21, first, the first laser light L1 (P-polarized light) and the second laser light L2 (S-polarized light) whose polarization directions are different from each other by 90 degrees. The light is split by the polarizing beam splitter 22. Next, the first laser light L1 passes through the polarizing beam splitter 10i and the quarter-wave plate 10h and is incident perpendicularly on the surface of the substrate W. The second laser light L2 is reflected by the mirror 23, becomes parallel to the first laser light L1, passes through the quarter-wave plate 10h, and enters the surface of the substrate W.

Next, the first laser light L1 specularly reflected by the surface of the substrate W passes through the quarter-wave plate 10h, changes its polarization direction, and becomes S-polarized light. The first laser light L1 (S-polarized light) is reflected by the polarization beam splitter 10i, enters the first position detection element 10e, and
Is detected by the position detection element 10e. Further, the second mirror reflected by the surface of the substrate W
Laser light L2 passes through the quarter-wave plate 10h, changes its polarization direction, and becomes P-polarized light. The second laser light L2 (P-polarized light) is reflected by the mirror 23 toward the polarization beam splitter 22, passes through the polarization beam splitter 22, and enters the second position detecting element 10f, where It is detected by the position detecting element 10f. Subsequent processing (calculation of the curvature of the substrate W, warning notification, etc.) is the same as in the first embodiment.

In addition, on the optical path of the first laser light L1 between the first position detecting element 10e and the polarizing beam splitter 10i, and on the optical path of the second laser light L2 between the second position detecting element 10f and the polarizing beam splitter 22, It is also possible to provide a turning part such as a turning mirror so as to reflect the laser light in the upward direction in FIG. 8, for example. In this case, the first position detecting element 10e
In addition, the degree of freedom in setting the second position detecting element 10f can be improved.

Further, the first laser light L1 is perpendicularly incident on the surface of the substrate W, and furthermore, the second laser light L1
While maintaining that the laser beam 2 is incident on the surface of the substrate W in parallel to the first laser light L1, the polarization beam splitter 22, the mirror 23, the polarization beam splitter 10i, and the like are tilted so that the first position detection element 10e and the polarization It is also possible to make the optical path of the first laser beam L1 between the beam splitters 10i and the optical path of the second laser beam L2 between the second position detecting element 10f and the polarizing beam splitter 22 non-parallel.

Although the two beam splitters 10i and 22 used in the third embodiment shown in FIG. 8 are both of the P-polarized light transmission type, the same function is realized even if the two beam splitters are both of the S-polarized light transmission type. can do. Further, the first polarization beam splitter 22 and the second polarization beam splitter 10i may be of different transmission types (S transmission type and P transmission type). In this case, as shown in FIG. 9, the second polarization beam splitter 10i is placed between the mirror 23 and the quarter-wave plate 10h in the optical path of the second laser light L2. The first position detection element 10e detects the position of the first laser beam L1 reflected by the first polarization beam splitter 22, and
The position detection element 10f detects the position of the second laser beam L2 reflected by the second polarization beam splitter 10i.

In recent years, the size of the window of the chamber 2 has been reduced, and the restrictions on the window have become strict. In order to respond to the miniaturization of the window and to reduce the noise due to the deformation of the window and the restriction on the space on the chamber 2, the measurement by the vertical incident reflection is performed. Therefore, it is desired to suppress the loss of light quantity. As described above, since the laser beam is split into the first laser beam L1 and the second laser beam L2 by the polarization beam splitter 22, the amount of the laser beam is reduced by half, but after the separation, the first laser beam L1 and the second laser beam L2 are separated. Even if the two laser beams L2 are reflected by the optical system such as the polarization beam splitter 10i and the mirror 23, the respective light amounts hardly decrease, and the loss of the light amounts can be suppressed. Therefore, in the measurement by the vertical incident reflection, there is no remarkable decrease (unnecessary scattering) of the light from the incident to the reflection, and the loss of the light amount can be suppressed.

Furthermore, in the measurement by the vertical incident reflection, the first laser light L1 and the second laser light L2 always keep their polarization directions orthogonal to each other after separation, so that the two laser lights L1 and L2 are separated by any factor. Even if the laser beams L1 and L2 overlap, it is possible to prevent the curvature measurement from being disabled, and also to improve the curvature measurement accuracy. In the measurement by the vertical incident reflection, it is possible to change only the direction of the reflected light to the direction of a detector such as the first position detecting element 10e or the second position detecting element 10f.

As described above, according to the third embodiment, the first laser light L1 and the second laser light L2 whose polarization directions are different from each other are made incident on the substrate W in parallel, and are specularly reflected by the substrate W. The first laser light L1 and the second laser light L2 are not mixed but detected by the first position detecting element 10e and the second position detecting element 10f, respectively. Note that each of the laser beams L1 and L2
Are not necessarily strictly parallel, but may be approximately parallel. For this reason, unlike the case of using the conventional two-point collective CCD method, the two points on the element surface of the CCD do not coincide with each other, and even if the two laser beams L1 and L2 overlap, the polarization property does not increase. And are detected by two position detecting elements 10e and 10f, respectively. Accordingly, unlike the conventional two-point collective CCD method, measurement is not impossible, and the deterioration of the S / N ratio (S / N) is suppressed even when the warpage is large or the distance between the two points is narrow. It becomes possible. Therefore, it is possible to suppress the curvature measurement from being impossible and improve the curvature measurement accuracy.

Further, after the laser light is separated, even if the first laser light L1 and the second laser light L2 are reflected by optical systems such as the polarizing beam splitter 10i and the mirror 23, the respective light amounts hardly decrease. Loss can be reduced. In addition, by adopting the measurement based on the vertical incident reflection, the window of the chamber 2 through which each of the laser beams L1 and L2 passes can be made smaller, so that the detection position accuracy is reduced by the inclination of the window due to heat or the like. Can be suppressed.

(Other embodiments)
In the first to third embodiments described above, each of the laser beams L1 and L2 is not formed into a sheet shape, but is not limited thereto, and may be formed into a sheet shape. For example, as shown in FIG. 10, each of the laser beams L1 and L2 is converted into one-dimensional position detection elements 10e and 10f in the element row direction (longitudinal direction) by a shaping part 10j such as a semi-cylindrical lens or a unidirectional diffusion filter. The sheet may be stretched in a direction perpendicular to the sheet (transverse direction) and formed into a sheet extending in the transverse direction. The molding unit 10j is provided on an optical path between the irradiation unit 10a and the substrate W.
Accordingly, even when the laser beams L1 and L2 are displaced in the short direction of the one-dimensional position detecting element 10e or 10f due to periodic vibration (for example, vibration of the substrate W due to rotation), the laser light L1 and L2 remain in the short direction. Since it is in the form of a sheet, it surely enters the condenser lens 10c (even without the condenser lens 10c, it surely enters the one-dimensional position detecting element 10e or 10f). As a result, the laser beams L1 and L2 are condensed by the condensing lens 10c and surely enter the one-dimensional position detecting element 10e or 10f. Therefore, it is possible to suppress a decrease in position detection accuracy due to periodic vibration. it can. When a periodic vibration occurs on the substrate W, the laser light L1 or L2 not only shifts in the short direction of the position detection element 10e or 10f, but also rotates the substrate W of the measurement target. It shifts in a circle according to the rotation. Even in such a case, since each of the laser beams L1 and L2 is in the form of a sheet in the above-described lateral direction, it is surely incident on the condenser lens 10c.

In the above-described first to third embodiments, the irradiation unit 10a is arranged in parallel or in parallel by the laser light emission unit 21, the polarization beam splitter 22, the mirror 23, and the like.
Although the first laser light L1 and the second laser light L2 are generated, the present invention is not limited thereto. For example, the first laser light L1 and the second laser light L2 may be parallel or parallel using two laser light emitting units. Laser light L
It is also possible to generate the first and second laser beams L2. Since the light amounts of the laser beams L1 and L2 tend to be reduced due to the presence of the window of the chamber 2 or the like, the use of two laser light emitting portions makes the light amount smaller than the case of using one laser light emitting portion. Can be raised. In this case, it is possible to eliminate the need for the incident side polarization beam splitter 22 and the like. However, since there is a polarizing plate for improving the polarization and the size of the laser beam emitting unit main body, two polarizing plates are required. It is desirable to provide a mirror for bringing the laser beams L1 and L2 closer to each other, a cooling system for the laser beam emitting unit body, and the like. Further, a space for installing the curvature measuring device 10 (
Since the upper portion of the film forming apparatus 1 is narrow, the housing is preferably small. To avoid the increase in the number of components described above, light can be brought in from an external light source by a fiber or the like.

In the above-described first to third embodiments, the curvature measuring device 10 measures the warpage of the substrate W. However, the present invention is not limited to this. For example, the curvature may be applied in addition to the warpage. Thus, it is possible to measure the inclination, the height position, and the like of the substrate W.

In the first to third embodiments, the shower plate 4 and the curvature measuring device 10 are not cooled. However, the present invention is not limited to this. For example, the shower plate 4 and the curvature measuring device 10 are not cooled. It is also possible to provide a cooling device for cooling the shower plate 4, the curvature measuring device 10, and the like.

In the embodiments described so far, the second polarization beam splitter causes one of the laser beams reflected from the object to be measured to pass through the plane including the optical paths of the two laser beams incident on the object to be measured. (Directions in the plane of the paper in FIGS. 2, 3, and 7 to 10). On the other hand, it is also possible to make the reflection direction perpendicular to the above-mentioned plane (perpendicular to the plane of the paper in FIGS. 2, 3, and 7 to 10). This can be realized by simply rotating the installation of the second polarizing beam splitter by 90 ° about the optical path of the incident laser light as an axis. By making these changes,
The degree of freedom of the shape of the curvature measuring device of the present embodiment is increased, and the curvature measuring device can be easily installed in a restricted space.

When the above-described change of the reflection direction is performed, the polarization is reversed because the second polarization beam splitter is rotated by 90 °. It should be noted that the S or P polarized laser light originally becomes P or S polarized light in the polarized beam splitter rotated as described above. Further, when the above-described change in the reflection direction is performed, the change in the position of the laser light reflected by the second polarization beam splitter on the position detector due to the change in the curvature of the measurement object is rotated by 90 °. Specifically, FIG.
11 and 12, the effect of rotating the second polarizing beam splitter by 90 ° as described above is shown in FIGS. FIG. 11 shows the relationship between the joining surface of the second polarization beam splitter 10d, the incident laser light, and the laser light reflected by the second polarization beam splitter 10d in the case of FIG. It is shown. As shown in FIG. 11, the direction of the laser beam reflected by the second polarization beam splitter 10d changes substantially in the vertical direction corresponding to the change in the warpage of the substrate W that is the measurement target. This change in position is shown in FIG.
Is substantially in the vertical direction on the paper surface. On the other hand, FIG. 12 shows the second polarization beam splitter 10d as 90
Shows the case when rotated. As shown in FIG. 12, the laser beam reflected by the second polarization beam splitter 10d is reflected in a direction perpendicular to the plane of FIG. The direction of the laser light reflected by the second polarization beam splitter 10d changes in a substantially horizontal direction in accordance with the change in the warp of the measurement object. It should be noted that this is substantially in the horizontal direction in FIG.

Further, taking the case of FIG. 9 as an example, consider a case where the second polarization beam splitter 10i is rotated by 90 ° about the direction of the second laser beam L2 as an axis. In this case, by making the second polarization beam splitter 10i a P-polarized light transmission type, a function equivalent to the configuration in FIG. 9 can be realized. However, the direction in which the second laser beam L2 is reflected is a direction perpendicular to the plane of FIG.

In this embodiment, the film formation by MOCVD is cited as a main application example. However, if there is a possibility that the warpage of the substrate accompanying the film formation may occur, not only the MOCVD but also a method such as sputtering or vapor deposition is used. Needless to say, the present invention is applicable to general warpage measurement not limited to film formation. In the present embodiment, a single-wafer type apparatus is described as a main application example. However, the present invention is not limited to a single-wafer type apparatus, and is also applied to, for example, a batch processing apparatus (simultaneous processing of a plurality of sheets). It is possible.

While some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other forms, and do not depart from the gist of the invention.
Various omissions, replacements, and changes can be made. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

DESCRIPTION OF SYMBOLS 1 Film-forming apparatus 2 Chamber 3 Gas supply part 3a Gas storage part 3b Gas pipe 3c Gas valve 4 Shower plate 4a Gas supply flow path 4b Gas discharge hole 5 Susceptor 5a Opening part 6 Rotating part 6a Cylindrical part 6b Rotating body 6c Shaft 7 Heater 7a Wiring 8 Gas exhaust unit 9 Exhaust mechanism 9a Gas exhaust flow path 9b Exhaust valve 9c Vacuum pump 10 Curvature measuring device 10a Irradiation unit 10b Optical filter 10c Condenser lens 10d Route change unit 10e First position detecting element 10f Second position detection Element 10g Calculation unit 10h Quarter-wave plate 10i Polarization beam splitter 10j Molding unit 11 Control unit 12 Notification unit 21 Laser beam emission unit 22 Polarization beam splitter 23 Mirror L1 First laser beam L2 Second laser beam R1 First region R2 Second area W substrate

Claims (5)

Either the first laser light or the second laser light is reflected such that the first laser light and the second laser light, which have different polarization directions and traveling directions, respectively, travel to the measurement object in parallel. A reflector,
One of the first laser light and the second laser light specularly reflected by the measurement object is transmitted, and the other is reflected in a direction different from the traveling direction of the one, thereby separating the laser light in a different direction. A one-dimensional first position detecting element that detects respective incident positions of the obtained first laser light and the second laser light, and a one-dimensional second position detecting element;
A curvature measuring device comprising:   The displacement amount of the incident position of the first laser beam detected by the first position detecting element and the displacement amount of the incident position of the second laser beam detected by the second position detecting element A calculating unit that calculates a difference, and calculates a curvature change amount of the measurement object from a correlation between the calculated difference and individual optical path lengths of the first laser light and the second laser light. The curvature measuring device according to claim 1, wherein   The first position detecting element and the second position detecting element detect a displacement of a shortest distance between two lines of the first laser light and the second laser light reflected by the measurement object. The curvature measuring device according to claim 1 or 2, wherein   The first laser light is focused in a direction perpendicular to the element row direction of the first position detection element, and the second laser light is focused in a direction perpendicular to the element row direction of the second position detection element. The curvature measuring device according to claim 1, further comprising a condenser lens that collects light. One of the first laser light and the second laser light is reflected by the reflection unit so that the first laser light and the second laser light, which have different polarization directions and traveling directions, respectively, travel to the measurement object in parallel. Reflecting by;
A step of transmitting one of the first laser light and the second laser light specularly reflected by the measurement object and reflecting the other in a direction different from the traveling direction of the one,
A step of detecting the incident position of the first laser light by a one-dimensional first position detecting element;
A step of detecting the incident position of the second laser beam with a one-dimensional second position detecting element;
A curvature measuring method characterized by having:

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