Classifications

• • 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
  • G03F7/20—Exposure; Apparatus therefor
  • G03F7/2022—Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure
  • G03F7/2024—Multi-step exposure, e.g. hybrid; backside exposure; blanket exposure, e.g. for image reversal; edge exposure, e.g. for edge bead removal; corrective exposure of the already developed image
• • 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
  • G03F7/004—Photosensitive materials
  • G03F7/038—Macromolecular compounds which are rendered insoluble or differentially wettable
  • G03F7/0382—Macromolecular compounds which are rendered insoluble or differentially wettable the macromolecular compound being present in a chemically amplified negative photoresist composition
• • 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
  • G03F7/004—Photosensitive materials
  • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
  • G03F7/0392—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition
• • 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
  • G03F7/004—Photosensitive materials
  • G03F7/09—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers
  • G03F7/11—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers having cover layers or intermediate layers, e.g. subbing 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
  • G03F7/16—Coating processes; Apparatus therefor
• • 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
  • G03F7/16—Coating processes; Apparatus therefor
  • G03F7/162—Coating on a rotating support, e.g. using a whirler or a spinner
• • 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
  • G03F7/20—Exposure; Apparatus therefor
  • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
  • G03F7/2004—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light
• • 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
  • G03F7/26—Processing photosensitive materials; Apparatus therefor
  • G03F7/38—Treatment before imagewise removal, e.g. prebaking
• • 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
  • G03F7/26—Processing photosensitive materials; Apparatus therefor
  • G03F7/40—Treatment after imagewise removal, e.g. baking
• • 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
  • G03F7/26—Processing photosensitive materials; Apparatus therefor
  • G03F7/40—Treatment after imagewise removal, e.g. baking
  • G03F7/405—Treatment with inorganic or organometallic reagents after imagewise removal
• • G—PHYSICS
  • G06—COMPUTING OR CALCULATING; COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F18/00—Pattern recognition
  • G06F18/20—Analysing
  • G06F18/22—Matching criteria, e.g. proximity measures

Definitions

• This invention relates to patterning critical dimension uniformity (CDU) control. Specifically, the disclosure relates to incorporation of photo-sensitized chemically amplified resist (PSCAR) chemistries into the resist matrix for better/alternative CDU control methods.
• PSCAR photo-sensitized chemically amplified resist
• a PSCAR is a resist composition formulated for a two-exposure treatment to fully create a latent pattern prior to developing the resist. Such double exposure differs from use of conventional photoresists wherein a single exposure of radiation through a mask generates an area of de-protected (positive-tone) or protected (negative-tone) material that defines a soluble or insoluble area for subsequent development.
• a PSCAR in contrast, can include a non- chemically selective light exposure followed by a chemically selective light exposure prior to developing the resist.
• the first (non-chemically selective) exposure of the photoresist material typically occurs through a mask at a first radiation wavelength or wavelength range.
• This first exposure creates areas in the photoresist that become sensitive to a secondary chemically- selective exposure.
• the second (chemically selective) exposure combined traditionally with a bake process, then causes these chemically-sensitive areas to change the solubility of the PSCAR in those areas.
• the acid created allows for an autocatalytic de -protection reaction(s) of the polymer backbone at protected sites (typically involving a bake), thus changing the solubility of the resist during a subsequent develop.
• a target latent image or pattern is then fully created, having the desired de-protection profile, and such a resist film can then be developed into a relief pattern. More details on using photo-sensitized chemically amplified resists can be found in S. Tagawa et al., "Super High Sensitivity Enhancement by Photo-Sensitized Chemically Amplified Resist Process", Journal of Photopolymer Science and Technology, Vol. 26, Number 6 (2013), pp. 825-830.
• PSCAR photoresist lithographic patterning when photon density is low, such as when using EUV (extreme ultraviolet) wavelengths for exposure patterning.
• a photosensitizer is created during the initial EUV (or eBeam, or excimer laser such as using krypton fluorine (KrF), argon fluorine (ArF), etc.) exposure by the reaction of intermediates.
• a subsequent UV (ultraviolet) flood exposure enables the photosensitizer to cause a photo acid generator (PAG) to generate acid, which in turn shifts a solubility of the PSCAR via an autocatalytic de-protection reaction between the generated acid and protected polymer sites.
• PAG photo acid generator
• a choice of UV flood wavelength can be based on the particular characteristics of a given photosensitizer. It is typically beneficial to select a wavelength (or wavelength range) that maximizes absorbance by the photosensitizer while minimizing the absorbance by the PAG and precursor to the photosensitizer. Such optimization helps prevent the flood exposure from generating acid in areas in which no photosensitizer has been created.
• photosensitizer having absorbed UV light from the UV flood exposure, will then decompose PAGs in proximity to the photosensitizer. This decomposition amplifies acid generation in the exposed area while essentially keeping the lack of acid formation in dark areas from the initial EUV (or eBeam, or excimer laser) exposure. This means avoiding a DC-bias shift in films associated with flood UV exposure.
• CD uniformity can vary across a surface of a substrate.
• a given wafer can have one CD value in a center portion of the wafer, while having another CD value closer to an edge of a wafer.
• a wafer can also have CDs that vary based on order of exposure progression, such as when using a stepper exposure system.
• CDs may be too large or too small, and the CD variation may be spread randomly across the wafer, may be based on radial location, and/or may correlate with particular features such as location of scribe lanes.
• CD control of the patterning step has involved one of three methods.
• the first method is the CD Optimizer (CDO) by TEL, in which critical dimension control is by zonal temperature compensation during post-exposure bake (PEB).
• the second method is the DoseMapper (DoMa) by ASML, in which critical dimension control is by intrafield and/or interfield dose compensation during exposure.
• the third method is Hydra by Lam Research, in which critical dimension control is by zonal temperature control during etch.
• the method comprises receiving a substrate having an underlying layer and a radiation-sensitive material layer deposited on the underlying layer.
• the method further comprises exposing a first wavelength of light through a patterned mask onto the radiation- sensitive material layer, the first wavelength of light comprising a wavelength in the UV spectrum; first developing the pattern-exposed radiation- sensitive material layer; flood exposing a second wavelength of light to the first developed radiation- sensitive material layer, the second wavelength of light comprising a wavelength that is different from the first wavelength of light; and second developing the flood-exposed radiation- sensitive material layer to form a radiation- sensitive material pattern.
• the radiation- sensitive material Prior to the step of flood exposing, the radiation- sensitive material comprises a first light wavelength activation threshold that controls the generation of acid to a first acid concentration in the radiation- sensitive material layer and controls generation of photosensitizer molecules in the radiation- sensitive material layer, and a second light wavelength activation threshold that can excite the photosensitizer molecules in the radiation- sensitive material layer that results in the acid comprising a second acid concentration that is greater than the first acid concentration, the second light wavelength activation threshold being different than the first light wavelength activation threshold.
• the radiation sensitive material pattern comprises a corrected or slimmed critical dimension (CD) across the entire substrate or a portion of the substrate, following the second developing step.
• FIG. 1A is a graph depicting the acid and photosensitizer concentrations after a first patterned exposure
• FIG. IB is a graph depicting the acid and photosensitizer concentrations after a second flood exposure
• FIG. 2 is a graph depicting the selective absorption of UV light with a photosensitizer
• FIG. 3 is a table illustrating the various pathways to alter the radial dose signature delivered within-wafer to alter the final critical dimension uniformity signature
• FIG. 4 is a flow chart depicting processes for critical dimension control according to embodiments of the invention.
• the first embodiment of this invention proposes the use of a PSCAR chemistry rather than a conventional CAR chemistry for use as a multi-patterning resist material.
• a PSCAR includes a photoresist having a segregated activation capability that enables the generation of chemicals within the photoresist to occur at different times and under different process conditions.
• the PSCAR chemistry creates a background photosensitizer (PS) concentration profile 120 at a time of primary exposure (or during the time between the primary and the secondary exposures) that follows the initial acid concentration profile 110 generated.
• PS background photosensitizer
• the primary exposure wavelength can be, but is not limited to, EUV (13.5nm), ArF (193nm) (dry or immersion), and/or KrF (248nm). Some acid may be formed during the primary exposure, for example, from PAGs inside the PSCAR, to form the acid concentration profile 110, although in other embodiments no acid is formed.
• the secondary exposure wavelength (UV flood) is at an alternative wavelength, often trying to escape the absorption of other components within the resist matrix and thus is usually required to be >300nm, for example, 365nm can be used.
• the PS generated as a result of the primary exposure can then be used to alter the acid generated by amplifying the decomposition of PAGs into acid in subsequent processing.
• FIG. IB shows graph 130 of photosensitizer (PS) and acid concentration profiles, 150 and 140, respectively, following the secondary exposure.
• an excited photosensitizer from the UV flood exposure at the secondary exposure wavelength, will decompose PAGs in the proximity of the excited photosensitizer to get amplification of acid generation in the exposed area while essentially keeping the lack of acid formation in the dark area (unexposed) of the original exposure (meaning no significant DC-bias shift of all film associated with flood UV exposure).
• a resist composition is created (or selected) to generate photosensitizer when the resist (as a film) is exposed to a first wavelength range of light.
• a second wavelength range of light is then used to amplify an acid reaction without using thermal diffusion.
• the first and second wavelength ranges may or may not overlap.
• the segregated activation capability may overlap between the photosensitizer and a photo acid generator, such that a relatively small amount of acid may be generated during the first exposure, as seen in FIG. 1A. This relatively small amount of acid may be, for example, less than half an amount of acid that may be generated during a second exposure.
• the photoresist may be optimized to minimize the reaction rate of the acid or an amount of acid that may be generated when the photoresist is exposed to the first wavelength range of light. Acid generation may also be minimized by passing light through a patterned mask that may reduce the amount of light that may intersect with photoresist during the first exposure of light.
• the photoresist film is exposed to light again. This subsequent exposure can include a second wavelength range that induces or amplifies the acid concentration within the photoresist film.
• the first wavelength range may be less than 300nm and the second wavelength range may be greater than 300nm.
• a first light exposure activates a PAG at exposure locations such that photo acid is generated at those locations.
• the photo acid can then change a solubility of the photoresist film via an autocatalytic de-protection reaction between the generated acid and protected polymer sites.
• a mask-based pattern exposure of light which is at a lower power than the conventional process, primarily creates photosensitizers along with a much smaller amount of acid compared to the conventional process.
• Photosensitizers can be created or generated by a photosensitizer generation compound, which is a precursor to the photosensitizer, reacting with acid molecules that are in proximity to change the photosensitizer generation molecules into the photosensitizer.
• This initial mask-based exposure can be considered a low-power exposure relative to the power of the conventional process.
• a high-power UV flood exposure is executed that creates an enormous amount of acid relative to what was created with the mask-based exposure.
• Flood exposure herein refers to light exposure without any mask or patterning mechanism so that all portions of a substrate receive about the same amount of radiation.
• Embodiments herein can include a resist composition that includes one or more photosensitizer generation compounds. Such compounds respond to a particular light wavelength activation threshold by generating photosensitizer molecules in a photoresist layer or composition. Photosensitizer molecules can absorb light energy and transfer the light energy to another molecule, such as a PAG. This energy transfer can in turn activate the receiving molecule. In the case of a PAG receiving the energy transfer, the PAG can then generate acid. Some photosensitizer compounds may transfer energy in a ground state while others may conduct the transfer in an excited state. Exemplary photosensitizer generation compounds include, but are not limited to, acetophenone, triphenylene, benzophenone, fluorenone, anthraquinone, phenanthrene, or derivatives thereof.
• Resist compositions herein can also include a PAG compound that responds to a second light wavelength activation threshold that controls the generation of acid in the photoresist layer.
• the second activation wavelength can be different than the first activation wavelength.
• a PAG can be a cationic photoinitiator that converts absorbed light energy into chemical energy (e.g., an acidic reaction).
• the PAG compound may include, but is not limited to triphenylsulfonium triflate, triphenylsulfonium nonaflate, triphenylsulfonium
• Embodiments herein can also include a photoactive agent that can modify acid concentration and/or concentration of a photosensitizer.
• the photoactive agent can include a second PAG, or a photo-destructive base, also known as a photo-decomposable base.
• a photo- destructive base can include one or more base compounds that decompose in the exposed areas, which allows for a higher total base loading that can neutralize photoactive acids in the non- exposed areas.
• a photo-destructive base thus includes compounds that can provide this general base loading effect.
• the non-decomposed base will denature one or more photo acids such that these photo acids are no longer photo-sensitive, or no longer sensitive to radiation.
• Common photoresist compositions typically include some type of a base load to help increase contrast to result in crisp lines.
• This base load typically acts to uniformly adjust acid concentration to provide a uniform profile (remove a gradient exposure). As disclosed herein, by adding more base to a given resist film, a given acid concentration can be reduced. Likewise, a given acid concentration can be increased by selectively adding acid compounds.
• the photosensitizer and/or photosensitizer generator is within the resist matrix from the beginning, but this doesn't preclude it from being dissolved in solution and incorporated via a spin-on process after the first development step, similar to acid rinse processes for slimming, and then subsequently exposed by the UV flood exposure process (at a secondary exposure wavelength), baked, and developed.
• CD within- wafer (WIW) distributions can be de-convolved into radial and tilt components.
• Radial signatures can be adjusted in one embodiment with the use of a rotating and translating substrate under a light source, during UV flood exposure. This hardware concept allows for many pathways to alter the radial dose signature delivered WrW to alter the final WfW CDU signature.
• the radial dose alteration can include variable settings for rotation, scan rate, power setting, light source working distance, use of apertures, focal position variation, light source zonal control, etc., to name a few, and any permutations thereof.
• the UV flood light energy (at the secondary exposure wavelength), delivered to the wafer can be controlled by use of digital pixel-based projection systems having an array of independently addressable projection points, the projected pattern being based on a CD signature that spatially characterizes CD values of structures.
• the digital pixel-based projection system can be embodied as a digital light processing (DLP) chip, a grating light valve (GLV), a galvanometer- mounted and -actuated mirror (“galvo-mirror”) to direct a light beam, or any other micro projection and/or scanning technology (“Other”), with a light source that can focus an image or pattern (optionally using a lens) onto a wafer and correct or adjust critical dimension non-uniformities.
• DLP digital light processing
• GLV grating light valve
• galvo-mirror galvanometer- mounted and -actuated mirror
• Other micro projection and/or scanning technology
• the digital pixel-based projection systems have historically had reliability issues (from absorption issues within the projection system) below 300nm wavelengths. While there are ways to engineer the operation at lower wavelengths, the absorbance of the PS material, in which 365nm is a preferred exposure wavelength, allows for potentially more reliable operation. A wavelength of 365nm is a significantly higher wavelength than that available to photolyze the existing PAGs within a majority of
• EUV/ArF/KrF resist systems given historical PAG absorption curves. With this in mind, the use of PSCAR chemistries/methods and subsequent 365nm flood exposure wavelength use potentially has the benefit of higher projection system lifetime and reliability.
• UV flood (at secondary exposure wavelength) by rotation/translation methods can be combined with digital pixel-based projection systems (at secondary exposure wavelength) to correct for CD non-uniformities.
• digital pixel-based projection systems at secondary exposure wavelength
• the rotation/translation flood hardware can deliver the majority of the required secondary exposure wavelength (e.g., 97%) and the digital pixel-based projection system can then deliver the remaining dose required for CD non-uniformity minimization (e.g., 0-3% across wafer).
• sub-process flows for the UV flood exposure include, but are not limited to:
• 300-400nm may be 365nm.
• the ability to maximize the CDU improvement requires the CD distribution be shifted such that the majority of the CDs across the wafer are on one side or the other of the nominal dimension required (depending on the develop tone), such that a secondary exposure has the ability to correct all areas of the wafer. Therefore, when incorporating the secondary PSCAR flood process(es), a shift to slightly under-dosing the primary exposure may be required. In other words, for a PSCAR process, which uses two exposure steps, the exposure dose of the first exposure step is reduced relative to the exposure dose in a CAR process, which uses a single exposure step.
• the embodiments herein offer several process control schemes and wafer sequence options.
• the secondary exposure(s) and post-secondary exposure bake
• DEV development
• the process begins at 410 with initial processing of the wafer.
• a thin film is added, which may be referred to as the underlying layer into which a pattern is to be transferred.
• a coating of radiation-sensitive material for example a photoresist, is applied over the thin film.
• a lithography process is performed on the radiation-sensitive material coating. More specifically, the radiation-sensitive material coating is exposed through a mask to a first wavelength ( ⁇ ) of light, which is in the UV spectrum, to create a patterned exposure.
• a post-exposure bake (PEB) is performed.
• the process can proceed in accordance with one embodiment, as indicated by branch 500 of flow chart 400.
• the pattern-exposed radiation- sensitive material coating is subjected to a first development process (1 st DEV).
• the developed radiation- sensitive material coating is coated with a photosensitizer (PS) generation compound or a PS compound to incorporate the PS generation compound or PS compound into the radiation- sensitive material coating.
• PS photosensitizer
• spin-coating may be used to apply the PS generation compound or the PS compound.
• acid present in the pattern-exposed radiation- sensitive material coating may then be reacted with the incorporated PS generation compound.
• step 520 may be omitted and a PS generation compound may be a component of the radiation- sensitive material coating when applied in 430 over the thin film, which PS generation compound is later reacted to generate PS.
• a flood process (or processes) is performed to flood expose the first developed radiation- sensitive material coating to a second wavelength ( ⁇ ) of light, which is different than the first wavelength ( ⁇ ) of light.
• the flood process may include, for example, any of the Sub Flows A-G described above, which include a flood bake.
• an after-develop inspection (ADI) may optionally be performed, at 530, as part of a feed-forward (FF) control strategy.
• ADI after-develop inspection
• FF feed-forward
• the process parameters of the flood exposure or flood bake in 540 can be altered based on a critical dimension signature obtained from inspecting the first-developed radiation- sensitive material coating, as indicated by the FF arrow in branch 500.
• a second development process (2 nd DEV) is performed at 550.
• the underlying thin film is etched using the patterned radiation-sensitive material coating as a mask.
• processing of the wafer continues with a Next Process. A new wafer may then be processed according to the flow chart 400 and branch 500.
• branch 500 of flow chart 400 may include ADI at 560 and/or an after-etch inspection (AEI) at 580, in which the wafer is inspected after the 2 nd DEV at 550 and/or after the etch at 570, respectively, as part of a feed-back (FB) control strategy.
• AEI after-etch inspection
• FB feed-back
• the process parameters of the flood exposure or flood bake in 540 can be altered for a next wafer being processed based on a critical dimension signature obtained from inspecting the second- developed radiation- sensitive material coating and/or the etched underlying thin film layer, as indicated by the FB arrows in branch 500.
• a flood process (or processes) is performed to flood expose the pattern-exposed radiation-sensitive material coating to a second wavelength ( ⁇ ) of light, which is different than the first wavelength ( ⁇ ) of light.
• the flood process 610 may include any of the Sub Flows A-G described above.
• a development process (DEV) is performed at 620, which is the only DEV step of this process flow.
• the underlying thin film is etched using the patterned radiation-sensitive material coating as a mask.
• processing of the wafer continues with a Next Process. A new wafer may then be processed according to the flow chart 400 and branch 600.
• branch 600 of flow chart 400 may include ADI at 630 and/or AEI at 650, in which the wafer is inspected after the DEV at 620 and/or after the etch at 640, respectively, as a part of a FB control strategy.
• the process parameters of the flood exposure or flood bake in 610 can be altered for a next wafer being processed based on a critical dimension signature obtained from inspecting the developed radiation-sensitive material coating and/or the etched underlying thin film layer, as indicated by the FB arrows in branch 600.
• the radiation-sensitive material coating comprises a first light wavelength activation threshold that controls the generation of acid to a first acid concentration in the radiation- sensitive material and controls generation of
• the photosensitizer molecules in the radiation- sensitive material and a second light wavelength activation threshold that can excite the photosensitizer molecules in the radiation-sensitive material that results in the acid comprising a second acid concentration that is greater than the first acid concentration, the second light wavelength activation threshold being different than the first light wavelength activation threshold.
• the first wavelength of light in 440
• the second wavelength of light in 540 or 610 is at or above the second light wavelength activation threshold.
• AEI averaged after-etch inspection
• ADI averaged after-develop inspection
• ADI results can be used from either ADI step (e.g., 530 and 560), and be fed back for next wafer process control.
• ADI step e.g., 530 and 560
• feed forward control strategies at the wafer level are enabled.
• a known ADI CD map can be fed forward into the flood controller to augment the flood process (dose delivered locally within-wafer) specific to that wafer for tighter final CD distribution at ADI. Any of the above control schemes used by themselves, or in conjunction, could lead to tighter patterning CD control.
• CDU control is herein largely controlled by UV flood dose control module(s).
• WIW control schemes can also be more realizable; they can make use of actual WIW information to feed forward to secondary exposure to allow for tighter patterning CD control.
• substrate refers to the object being processed in accordance with the invention.
• the substrate may include any material portion or structure of a device, particularly a semiconductor or other electronics device, and may, for example, be a base substrate structure, such as a semiconductor wafer, or a layer on or overlying a base substrate structure such as a thin film.
• substrate is not limited to any particular base structure, underlying layer or overlying layer, patterned or un-patterned, but rather, is contemplated to include any such layer or base structure, and any combination of layers and/or base structures.
• the description may reference particular types of substrates, but this is for illustrative purposes only.

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