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WO2010076254A1 - Procédé de détermination d'une caractéristique - Google Patents

Procédé de détermination d'une caractéristique Download PDF

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Publication number
WO2010076254A1
WO2010076254A1 PCT/EP2009/067620 EP2009067620W WO2010076254A1 WO 2010076254 A1 WO2010076254 A1 WO 2010076254A1 EP 2009067620 W EP2009067620 W EP 2009067620W WO 2010076254 A1 WO2010076254 A1 WO 2010076254A1
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WO
WIPO (PCT)
Prior art keywords
population
target
substrate
target population
forming
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2009/067620
Other languages
English (en)
Inventor
Henricus Megens
Jozef Finders
Antoine Kiers
Johannes Quaedackers
Maurits Van Der Schaar
Christian Leewis
Hendrik Van Laarhoven
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ASML Netherlands BV
Original Assignee
ASML Netherlands BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ASML Netherlands BV filed Critical ASML Netherlands BV
Priority to KR1020117017727A priority Critical patent/KR101330116B1/ko
Priority to JP2011542800A priority patent/JP5525547B2/ja
Priority to CN200980152725.XA priority patent/CN102265220B/zh
Publication of WO2010076254A1 publication Critical patent/WO2010076254A1/fr
Priority to IL213064A priority patent/IL213064A/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/0271—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers
    • H01L21/0273—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers characterised by the treatment of photoresist layers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
    • G03F7/70466—Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70616—Monitoring the printed patterns
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70616—Monitoring the printed patterns
    • G03F7/70625—Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70616—Monitoring the printed patterns
    • G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70681—Metrology strategies
    • G03F7/70683—Mark designs
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/706835—Metrology information management or control
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/706843—Metrology apparatus
    • G03F7/706851—Detection branch, e.g. detector arrangements, polarisation control, wavelength control or dark/bright field detection
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7073—Alignment marks and their environment
    • G03F9/7076—Mark details, e.g. phase grating mark, temporary mark
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7073—Alignment marks and their environment
    • G03F9/708—Mark formation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/544—Marks applied to semiconductor devices or parts, e.g. registration marks, alignment structures, wafer maps

Definitions

  • the present invention relates to a method of determining a characteristic of a substrate.
  • a lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate.
  • a lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs).
  • a patterning device which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC.
  • This pattern can be transferred onto a target portion (e.g., comprising part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate.
  • resist radiation-sensitive material
  • a single substrate will contain a network of adjacent target portions that are successively patterned.
  • lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the "scanning"-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate. [0004] In order to monitor the lithographic process, it is necessary to measure parameters of the patterned substrate, for example the overlay error between successive layers formed in or on it.
  • One form of specialized inspection tool is a scatterometer in which a beam of radiation is directed onto a target on the surface of the substrate and properties of the scattered or reflected beam are measured. By comparing the properties of the beam before and after it has been reflected or scattered by the substrate, the properties of the substrate can be determined. This can be done, for example, by comparing the reflected beam with data stored in a library of known measurements associated with known substrate properties. Two main types of scatterometer are known.
  • Spectroscopic scatterometers direct a broadband radiation beam onto the substrate and measure the spectrum (intensity as a function of wavelength) of the radiation scattered into a particular narrow angular range.
  • Angularly resolved scatterometers use a monochromatic radiation beam and measure the intensity of the scattered radiation as a function of angle.
  • the manufacture of IC chip involves the fabrication of many layers.
  • a plurality of lithography and etch processing steps may be used in the manufacture of each layer: this is known as double patterning.
  • double patterning There are a number of different methods of achieving double patterning.
  • the first of these is known as lithographic-etch-lithography- etch (LELE) and in this a first pattern is exposed and etched.
  • a second pattern, with features located in the spaces between the features of the first pattern, is then exposed and etched.
  • LFLE lithography-freeze-lithography-etch
  • a pattern is exposed in the resist, which is then frozen.
  • a second pattern can then also be exposed in the resist and both patterns are then etched into the substrate.
  • Another double patterning method is known as the spacer method.
  • the spacer method a sacrificial template is put down and spacers placed either side, and adjacent to, the sacrificial template. The template is then removed and the resulting pattern etched into the substrate.
  • the features exposed during the first lithography step may not be identical to those exposed during the second lithography step.
  • the features exposed during each lithography step may be different and need to be assessed separately.
  • the features exposed during the first and second lithography step are, necessarily, very similar and form a regular pattern it can be difficult to distinguish between the two sets of features using angular resolve scatterometry.
  • an inspection apparatus configured to measure a property of a substrate, a method of determining a characteristic of either a first population or a second population of features on a substrate, said first and second population being nominally (e.g., substantially) identical and forming (e.g., producing) a single pattern within a single layer on a substrate, said pattern having a period equal to the distance between a feature of said first population and the nearest feature of said second population, said method comprising: forming a first population on said substrate, said first population comprising a first target population; forming a second population on said substrate, said second population comprising a second target population, said second target population and said first target population forming a combined target population; detecting radiation reflected from said combined target population; and calculating a characteristic of either said first population or said second population using radiation reflected from said target, wherein said second target population has an asymmetry with respect to said first target population.
  • Figure 1 depicts a lithographic apparatus, according to an embodiment of the present invention
  • Figure 2 depicts a lithographic cell or cluster, according to an embodiment of the present invention
  • Figure 3 depicts a first scatterometer, according to an embodiment of the present invention
  • Figure 4 depicts a second scatterometer, according to an embodiment of the present invention
  • Figure 5 depicts a pattern exposed using a double patterning technique, according to an embodiment of the present invention
  • Figure 6 is a graph depicting how the intensity of the zeroth order diffraction pattern varies with the overlay error, according to an embodiment of the present invention
  • Figure 7a depicts a pattern in which there is an overlay error between the first and second populations, according to an embodiment of the present invention
  • Figure 7b depicts a target population in which there is a bias and an overlay error between the first and second target populations, according to an embodiment of the present invention
  • Figure 8a depicts a stage in the spacer patterning technique and the resulting pattern, according to an embodiment of the present invention
  • Figure 8b depicts a stage in the manufacture of a target using a spacer patterning technique and the resulting target, according to an embodiment of the present invention
  • Figure 9 depicts a target manufactured according to an embodiment of the present invention
  • Figure 10 depicts another target according to an embodiment of the present invention.
  • Figure 11 depicts a target according to an embodiment of the present invention.
  • Embodiments of the invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by one or more processors.
  • a machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device).
  • a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others.
  • the apparatus comprises an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., UV radiation or DUV radiation); a support structure (e.g., a mask table) MT constructed to support a patterning device (e.g., a mask) MA and connected to a first positioner PM configured to accurately position the patterning device in accordance with certain parameters; a substrate table (e.g., a wafer table) WT constructed to hold a substrate (e.g., a resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate in accordance with certain parameters; and a projection system (e.g., a refractive projection lens system) PL configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g., comprising one or more dies) of the substrate W.
  • a radiation beam B e.g., UV radiation or DUV radiation
  • a support structure e.g.
  • the illumination system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping, or controlling radiation.
  • the support structure supports, i.e., bears the weight of, the patterning device. It holds the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as for example whether or not the patterning device is held in a vacuum environment.
  • the support structure can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device.
  • the support structure may be a frame or a table, for example, which may be fixed or movable as required.
  • the support structure may ensure that the patterning device is at a desired position, for example with respect to the projection system. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device.”
  • patterning device used herein should be broadly interpreted as referring to any device that can be used to impart a radiation beam with a pattern in its cross-section such as to create a pattern in a target portion of the substrate. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so called assist features. Generally, the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in the target portion, such as an integrated circuit.
  • the patterning device may be transmissive or reflective.
  • Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels.
  • Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types.
  • An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in a radiation beam, which is reflected by the mirror matrix.
  • projection system used herein should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system”.
  • the apparatus is of a transmissive type (e.g., employing a transmissive mask).
  • the apparatus may be of a reflective type (e.g., employing a programmable mirror array of a type as referred to above, or employing a reflective mask).
  • the lithographic apparatus may be of a type having two (e.g., dual stage) or more substrate tables (and/or two or more mask tables). In such "multiple stage” machines the additional tables may be used in parallel, or preparatory steps may be carried out on one or more tables while one or more other tables are being used for exposure.
  • the lithographic apparatus may also be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g., water, so as to fill a space between the projection system and the substrate.
  • a liquid having a relatively high refractive index e.g., water
  • An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems.
  • immersion as used herein does not mean that a structure, such as a substrate, must be submerged in liquid, but rather only means that liquid is located between the projection system and the substrate during exposure.
  • the illuminator IL receives a radiation beam from a radiation source SO.
  • the source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In such cases, the source is not considered to form part of the lithographic apparatus and the radiation beam is passed from the source SO to the illuminator IL with the aid of a beam delivery system BD comprising, for example, suitable directing mirrors and/or a beam expander. In other cases the source may be an integral part of the lithographic apparatus, for example when the source is a mercury lamp.
  • the source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system.
  • the illuminator IL may comprise an adjuster AD for adjusting the angular intensity distribution of the radiation beam.
  • an adjuster AD for adjusting the angular intensity distribution of the radiation beam.
  • the illuminator IL may comprise various other components, such as an integrator IN and a condenser CO.
  • the illuminator may be used to condition the radiation beam, to have a desired uniformity and intensity distribution in its cross-section.
  • the radiation beam B is incident on the patterning device (e.g., mask MA), which is held on the support structure (e.g., mask table MT), and is patterned by the patterning device. Having traversed the mask MA, the radiation beam B passes through the projection system PL, which focuses the beam onto a target portion C of the substrate W.
  • the substrate table WT can be moved accurately, e.g., so as to position different target portions C in the path of the radiation beam B.
  • the first positioner PM and another position sensor can be used to accurately position the mask MA with respect to the path of the radiation beam B, e.g., after mechanical retrieval from a mask library, or during a scan.
  • movement of the mask table MT may be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM.
  • movement of the substrate table WT may be realized using a long-stroke module and a short- stroke module, which form part of the second positioner PW.
  • the mask table MT may be connected to a short-stroke actuator only, or may be fixed.
  • Mask MA and substrate W may be aligned using mask alignment marks M1 , M2 and substrate alignment marks P1 , P2.
  • the substrate alignment marks as illustrated occupy dedicated target portions, they may be located in spaces between target portions (these are known as scribe-lane alignment marks).
  • the mask alignment marks may be located between the dies.
  • step mode the mask table MT and the substrate table WT are kept essentially stationary, while an entire pattern imparted to the radiation beam is projected onto a target portion C at one time (i.e., a single static exposure).
  • the substrate table WT is then shifted in the X and/or Y direction so that a different target portion C can be exposed.
  • step mode the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.
  • the mask table MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam is projected onto a target portion C (i.e., a single dynamic exposure).
  • the velocity and direction of the substrate table WT relative to the mask table MT may be determined by the (de-)magnification and image reversal characteristics of the projection system PL.
  • the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, whereas the length of the scanning motion determines the height (in the scanning direction) of the target portion.
  • the mask table MT is kept essentially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam is projected onto a target portion C.
  • a pulsed radiation source is employed and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan.
  • This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device, such as a programmable mirror array of a type as referred to above.
  • Combinations and/or variations on the above described modes of use or entirely different modes of use may also be employed.
  • the lithographic apparatus LA forms part of a lithographic cell LC, also sometimes referred to a lithocell or cluster, which also includes apparatus to perform pre- and postexposure processes on a substrate.
  • lithographic cell LC also sometimes referred to a lithocell or cluster
  • apparatus to perform pre- and postexposure processes on a substrate Conventionally these include spin coaters SC to deposit resist layers, developers DE to develop exposed resist, chill plates CH and bake plates BK.
  • a substrate handler, or robot, RO picks up substrates from input/output ports 1/01 , 1/O2, moves them between the different process apparatus and delivers then to the loading bay LB of the lithographic apparatus.
  • track control unit TCU which is itself controlled by the supervisory control system SCS, which also controls the lithographic apparatus via lithography control unit LACU.
  • SCS supervisory control system
  • LACU lithography control unit
  • An inspection apparatus is used to determine the properties of the substrates, and in particular, how the properties of different substrates or different layers of the same substrate vary from layer to layer.
  • the inspection apparatus may be integrated into the lithographic apparatus LA or the lithocell LC or may be a stand-alone device. To enable most rapid measurements, it is desirable that the inspection apparatus measure properties in the exposed resist layer immediately after the exposure.
  • the latent image in the resist has a very low contrast such that there is only a very small difference in refractive index between the parts of the resist which have been exposed to radiation and those which have not and not all inspection apparatus have sufficient sensitivity to make useful measurements of the latent image.
  • measurements may be taken after the postexposure bake step (PEB) which is customarily the first step carried out on exposed substrates and increases the contrast between exposed and unexposed parts of the resist.
  • PEB postexposure bake step
  • the image in the resist may be referred to as semi-latent.
  • Figure 3 depicts a scatterometer which may be used in an embodiment of the present invention. It comprises a broadband (white light) radiation projector 2 which projects radiation onto a substrate W. The reflected radiation is passed to a spectrometer detector 4, which measures a spectrum 10 (intensity as a function of wavelength) of the specular reflected radiation. From this data, the structure or profile giving rise to the detected spectrum may be reconstructed by processing unit PU, e.g., by Rigorous Coupled Wave Analysis and non-linear regression or by comparison with a library of simulated spectra as shown at the bottom of Figure 3.
  • processing unit PU e.g., by Rigorous Coupled Wave Analysis and non-linear regression or by comparison with a library of simulated spectra as shown at the bottom of Figure 3.
  • Such a scatterometer may be configured as a normal-incidence scatterometer or an oblique-incidence scatterometer.
  • FIG. 4 Another scatterometer that may be used with the present invention is shown in Figure 4.
  • the radiation emitted by radiation source 2 is focused using lens system 12 through interference filter 13 and polarizer 17, reflected by partially reflected surface 16 and is focused onto substrate W via a microscope objective lens 15, which has a high numerical aperture (NA), for example, at least about 0.9 and at least about 0.95.
  • NA numerical aperture
  • Immersion scatterometers may even have lenses with numerical apertures over 1.
  • the reflected radiation then transmits through partially reflective surface 16 into a detector 18 in order to have the scatter spectrum detected.
  • the detector may be located in the back-projected pupil plane 11 , which is at the focal length of the lens system 15, however the pupil plane may instead be re-imaged with auxiliary optics (not shown) onto the detector.
  • the pupil plane is the plane in which the radial position of radiation defines the angle of incidence and the angular position defines azimuth angle of the radiation.
  • the detector is a two-dimensional detector so that a two- dimensional angular scatter spectrum of a substrate target 30 can be measured.
  • the detector 18 is an array of CCD or CMOS sensors, and may use an integration time of, for example, 40 milliseconds per frame.
  • a reference beam is often used for example to measure the intensity of the incident radiation. To do this, when the radiation beam is incident on the beam splitter 16 part of it is transmitted through the beam splitter as a reference beam towards a reference mirror 14. The reference beam is then projected onto a different part of the same detector 18.
  • a set of interference filters 13 is available to select a wavelength of interest in the range of, for example, about, 405 - 790 nm or even lower, such as about 200 - 300 nm.
  • the interference filter may be tunable rather than comprising a set of different filters.
  • a grating could be used instead of interference filters.
  • the detector 18 may measure the intensity of scattered light at a single wavelength, or narrow wavelength range, the intensity separately at multiple wavelengths or integrated over a wavelength range. Furthermore, the detector may separately measure the intensity of transverse magnetic- and transverse electric-polarized light and/or the phase difference between the transverse magnetic- and transverse electric-polarized light.
  • a broadband light source i.e., one with a wide range of light frequencies or wavelengths - and therefore of colors
  • the plurality of wavelengths in the broadband each has a bandwidth of *8 and a spacing of at least 2*8 (i.e., twice the bandwidth).
  • a plurality of "sources" of radiation may be different portions of an extended radiation source which have been split using fiber bundles. In this way, angle resolved scatter spectra can be measured at multiple wavelengths in parallel.
  • a 3-D spectrum for example, such as wavelength and two different angles, can be measured, which contains more information than a 2-D spectrum. This allows more information to be measured which increases metrology process robustness. This is described in more detail in European Patent No. 1 ,628,164A, which is incorporated by reference herein in its entirety.
  • the target 30 on substrate W may be a grating, which is printed such that after development, the bars are formed of solid resist lines.
  • the bars may alternatively be etched into the substrate.
  • This pattern is sensitive to chromatic aberrations in the lithographic projection apparatus, particularly the projection system PL, and illumination symmetry and the presence of such aberrations will manifest themselves in a variation in the printed grating. Accordingly, the scatterometry data of the printed gratings is used to reconstruct the gratings.
  • the parameters of the grating such as line widths and shapes, may be input to the reconstruction process, performed by processing unit PU, from knowledge of the printing step and/or other scatterometry processes.
  • Figures 7a and 7b show patterns exposed according to an embodiment of the present invention.
  • Figure 7a depicts the main pattern in which there is a single pattern made up of a first population, A, and a second population, B.
  • OV overlay error
  • Figure 7b depicts a target used in the first embodiment of the invention.
  • a first target population has been formed and a second target population then formed.
  • the second target population has a bias, ⁇ with respect to the first target population.
  • the deviation in placement of the second target population with respect to the first target population is equal to the bias, ⁇ , plus the overlay error OV. It is this introduced asymmetry which means that it is much easier to determine the overlay error.
  • the zeroth order diffraction pattern is detected and the deviation from the expected diffraction pattern used to determine the overlay error. Alternatively, it is easier to distinguish between the two populations and thus measure characteristics of the two populations such as the critical dimension or the side wall angle of either population.
  • Figures 8a and 8b depict a spacer method of double patterning according to an embodiment of the present invention.
  • spacer, 21 is used to generate spaces between the resist 22 and thus generate a regular pattern.
  • Figure 8b depicts the situation when the spacer 21 is too small and thus there is an overlay error OV between adjacent features or any parameter of either population.
  • a known bias would be introduced by deliberately modifying the size of the spacer and any characteristics of the features, such as those introduced by an error in the size of the spacer, assessed.
  • the bias may be any value but should be less than the period of the pattern. For example, for a pattern having a period of about 16 nm and a bias of about 5-10 nm is desired.
  • For improved calculation of the overlay error there may be a plurality of targets (e.g., each having their own target populations), each target having a different introduced bias.
  • FIG. 9 Another embodiment of the present invention is depicted in Figure 9. As can be seen, the second population B has a larger critical dimension than the first population A. Introducing this asymmetry again makes it easier to distinguish between the two populations and thus assess characteristics of each of the populations.
  • Figure 9 depicts the second population having a larger critical dimension, it could equally well have a smaller critical dimension or alternatively other characteristics of it such as the side wall angle varied. Indeed, any characteristic which will affect the zeroth order diffraction pattern may be varied in order to generate such an asymmetry.
  • Similar to the first embodiment there may a plurality of targets, each having a different critical dimension of the second target population.
  • Figure 10 depicts a target population in which there has been both a bias introduced and also the critical dimension of the second population varied, according to an embodiment of the present invention. This will again make it easier to distinguish between the different populations and thus measure the overlay error and characteristics of each population.
  • a further embodiment of the present invention is depicted in Figure 11 which depicts another target population.
  • this embodiment relates to the introduction of asymmetry into a target population.
  • asymmetry such as missing lines, a bias and a variation in critical dimension have been outlined above although any method of introducing an asymmetry would be suitable.
  • Further examples of asymmetries between the two populations would be the second population being a different height from the first population. Alternatively, different materials could be used for the different populations.
  • the invention is not limited to the use of just two populations and could equally well be applied when there are three or more populations.
  • lithographic apparatus in the manufacture of ICs
  • the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquid-crystal displays (LCDs), thin film magnetic heads, etc.
  • LCDs liquid-crystal displays
  • any use of the terms “wafer” or “die” herein may be considered as synonymous with the more general terms “substrate” or "target portion”, respectively.
  • the substrate referred to herein may be processed, before or after exposure, in for example a track, which is a tool that typically applies a layer of resist to a substrate and develops the exposed resist, a metrology tool and/or an inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers. [0066] Although specific reference may have been made above to the use of embodiments of the invention in the context of optical lithography, it will be appreciated that the invention may be used in other applications, for example imprint lithography, and where the context allows, is not limited to optical lithography.
  • a topography in a patterning device defines the pattern created on a substrate.
  • the topography of the patterning device may be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof.
  • the patterning device is moved out of the resist leaving a pattern in it after the resist is cured.
  • UV radiation e.g., having a wavelength of or about 365, 355, 248, 193, 157 or 126 nm
  • EUV radiation e.g., having a wavelength in the range of 5-20 nm
  • particle beams such as ion beams or electron beams.
  • lens may refer to any one or combination of various types of optical components, including refractive, reflective, magnetic, electromagnetic and electrostatic optical components.
  • the invention may take the form of a computer program containing one or more sequences of machine- readable instructions describing a method as disclosed above, or a data storage medium (e.g., semiconductor memory, magnetic or optical disk) having such a computer program stored therein.
  • a data storage medium e.g., semiconductor memory, magnetic or optical disk

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)

Abstract

Selon l'invention, une première population cible et une seconde population cible sont gravées dans un substrat. La seconde population cible présente une asymétrie par rapport à la première. Ceci peut permettre aux différentes populations cibles d'être distinguées et à des caractéristiques des différentes populations cibles d'être déterminées.
PCT/EP2009/067620 2008-12-30 2009-12-21 Procédé de détermination d'une caractéristique Ceased WO2010076254A1 (fr)

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KR1020117017727A KR101330116B1 (ko) 2008-12-30 2009-12-21 특성을 결정하는 방법
JP2011542800A JP5525547B2 (ja) 2008-12-30 2009-12-21 特性を求める方法
CN200980152725.XA CN102265220B (zh) 2008-12-30 2009-12-21 确定特性的方法
IL213064A IL213064A (en) 2008-12-30 2011-05-23 Method for setting a dimension

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US61/141,414 2008-12-30

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JP5760566B2 (ja) * 2011-03-23 2015-08-12 ソニー株式会社 光学素子、光学系、撮像装置、光学機器、および原盤
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CN102265220B (zh) 2014-03-12
TWI467346B (zh) 2015-01-01
IL213064A (en) 2016-03-31
JP5525547B2 (ja) 2014-06-18
CN102265220A (zh) 2011-11-30
JP2012516027A (ja) 2012-07-12
IL213064A0 (en) 2011-07-31
KR20110110263A (ko) 2011-10-06
TW201040669A (en) 2010-11-16
NL2003990A (en) 2010-07-01

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