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
  • G03F7/004—Photosensitive materials
  • G03F7/09—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers
  • G03F7/091—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers characterised by antireflection means or light filtering or absorbing means, e.g. anti-halation, contrast enhancement
• • 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
  • G03F7/70—Microphotolithographic exposure; Apparatus therefor
  • G03F7/70008—Production of exposure light, i.e. light sources
  • G03F7/70033—Production of exposure light, i.e. light sources by plasma extreme ultraviolet [EUV] sources
• • 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
  • G03F7/004—Photosensitive materials
  • G03F7/09—Photosensitive materials characterised by structural details, e.g. supports, auxiliary 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
  • G03F7/004—Photosensitive materials
  • G03F7/09—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers
  • G03F7/115—Photosensitive materials characterised by structural details, e.g. supports, auxiliary layers having supports or layers with means for obtaining a screen effect or for obtaining better contact in vacuum printing
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P76/00—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P76/00—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography
  • H10P76/20—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising organic materials
  • H10P76/204—Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography of masks comprising organic materials of organic photoresist masks
  • H10P76/2045—Electron beam lithography processes

Definitions

• the present disclosure relates to substrate processing systems and more particularly to EUV photolithography using an intervening layer or a multi-layer stack with varying mean free paths for secondary electron generation.
• Advanced photolithography is typically performed using excimer lasers, which have a wavelength of 193 nm.
• additional techniques such as multi-patterning, immersion and/or optical proximity correction can be performed to significantly increase resolution below 193 nm.
• further decreases to feature sizes using this type of photolithography are not possible.
• EUV photolithography uses extreme ultraviolet (EUV) wavelengths.
• a power source converts plasma into light at 13.5nm, which is 14 times shorter than 193 nm.
• EUV wavelengths require substantial changes to the photolithography process since most materials readily absorb photons at EUV wavelengths.
• EUV photolithography utilize multiple mirrors to reflect light rather than using lenses.
• the EUV photolithography process is also performed in a vacuum environment. Plasma sources are used instead of lasers to generate photons for printing.
• EUV radiation that is reflected by a mask pattern onto a photoresist layer.
• the photoresist layer absorbs EUV photons and generates secondary electrons. More particularly, EUV photons with sufficient energy ionize atoms in the photoresist layer, which releases secondary electrons.
• EUV photolithography is particularly sensitive to stochastic effects. When printing features using EUV, most features are resolved. Due to stochastic variations in arriving photon numbers, some regions designated to print actually fail to reach the threshold to print, which leaves unexposed regions or defects. The rate of failure is related to the dose level. However, increasing the dose level is difficult in EUV-based photolithography systems. Parameters such as dose-to-size and dose-to-defect may be used to characterize performance in EUV-based systems.
• a method for patterning a substrate comprises providing a substrate, and depositing a multi-layer stack including N layers on the substrate.
• N is an integer greater than one.
• the N layers include N mean free paths for secondary electrons, respectively.
• the method comprises depositing a photoresist layer on the multi-layer stack, wherein the N mean free paths converge in the photoresist layer.
• the N mean free paths of the N layers are different.
• the N layers are located at N distances from the photoresist layer, and the N mean free paths of the N layers increase with the N distances, respectively.
• the N layers are located at N distances from the photoresist layer, and the N mean free paths of the N layers monotonically increase with the N distances, respectively.
• the N layers are located at N distances from the photoresist layer, and the N mean free paths of the N layers linearly increase with the N distances, respectively.
• the N layers are located at N distances from the photoresist layer respectively have N absorption rates; and the N absorption rates of the N layers, respectively, increase as the N distances increase.
• each layer of the N layers has the same thickness.
• each layer of the N layers has a different thickness.
• the method further comprises arranging the N layers in an increasing order of thickness, with a thinnest layer of the N layers arranged adjacent to the photoresist layer and with a thickest layer of the N layers arranged adjacent to the substrate.
• the method further comprises exposing the photoresist layer to extreme ultraviolet radiation.
• the method further comprises exposing the photoresist layer to extreme ultraviolet radiation and removing exposed portions of the photoresist layer.
• the method further comprises removing portions of the multi-layer stack located in areas where the photoresist layer is removed.
• the method further comprises exposing the photoresist layer to extreme ultraviolet radiation and removing exposed portions of the photoresist layer to form a patterned photoresist layer.
• the method further comprises performing a deposition process using the patterned photoresist layer and removing the photoresist layer and the multi-layer stack after performing the deposition process.
• the method further comprises exposing the photoresist layer to extreme ultraviolet radiation and removing exposed portions of the photoresist layer to form a patterned photoresist layer.
• the method further comprises performing an etching process using the patterned photoresist layer and removing the photoresist layer and the multi-layer stack after performing the etching process.
• a method for patterning a substrate comprises providing a substrate and depositing a layer on the substrate.
• the layer includes varying mean free paths for secondary electrons.
• the method comprises depositing a photoresist layer on the layer. The varying mean free paths for secondary electrons converge in the photoresist layer.
• the varying mean free paths of the layer monotonically increase with a distance to the photoresist layer.
• the varying mean free paths of the layer linearly increase with a distance to the photoresist layer.
• the varying mean free paths of the layer increase in steps as a function of a distance to the photoresist layer.
• the method further comprises exposing the photoresist layer to extreme ultraviolet radiation.
• the method further comprises exposing the photoresist layer to extreme ultraviolet radiation and removing exposed portions of the photoresist layer.
• the method further comprises removing portions of the layer located in areas where the photoresist layer is removed.
• the method further comprises exposing the substrate to extreme ultraviolet radiation and removing exposed portions of the photoresist layer to form a patterned photoresist layer.
• the method further comprises performing a deposition process using the patterned photoresist layer and removing the layer and the photoresist layer after performing the deposition process.
• the method further comprises exposing the substrate to extreme ultraviolet radiation and removing exposed portions of the photoresist layer to form a patterned photoresist layer.
• the method further comprises performing an etching process using the patterned photoresist layer and removing the layer and the photoresist layer after performing the etching process.
• FIGs. 1 and 2 are side cross-sectional views of examples of substrates including a multi-layer stack with layers producing secondary electrons with varying mean free paths according to the present disclosure;
• FIG. 3 is a flowchart of an example of a method for patterning a substrate using EUV photolithography, according to the present disclosure;
• FIG. 4 is side cross-sectional view of an example of a substrate including a layer with a varying mean free path located between a photoresist layer and an underlying substrate according to the present disclosure
• FIGs. 5A and 5B are graphs illustrating examples of variations in the mean free path in the layer of FIG. 4.
• FIG. 6 is a flowchart of an example of a method for patterning a substrate using the EUV photolithography according to the present disclosure.
• a layer of film may be deposited between the photoresist layer and the underlying substrate.
• the layer enhances secondary electron generation, which improves dose-to-size and dose-to-defect parameters.
• this approach produces only a limited improvement in that the secondary electron generating layer can only produce a finite number of secondary electrons.
• Another approach improves dose-to-size and dose-to-defect using plasma etch smoothing techniques. By improving resist roughness, stochastic failures are mitigated, and lower dose specifications can be used for both size and defectivity. This approach also produces a finite limit on dose gains. However, this approach may be difficult to scale. As lithographic patterning films become thinner, etch techniques to improve roughness may become more limited as selectivity becomes a more critical consideration.
• a method for patterning substrates according to the present disclosure provides improvements in dose-to-size and dose-to-defect parameters for EUV photolithography.
• a multi-layer stack is deposited between the photoresist layer and the underlying substrate. Different layers of the multi-layer stack produce secondary electrons having different mean free paths. In some examples, the mean free paths of the layers in the multi-layer stack increase as a distance from the photoresist layer increases.
• the secondary electrons that are produced have a single mean free path, which results in a finite secondary electron density that can penetrate the photoresist layer.
• the multi-layer stack includes multiple layers having different mean free paths for secondary electrons.
• the mean free paths of the layers converge in the photoresist layer. For example, layers in the multi-layer stack that are located at a greater distance from the photoresist layer have a higher mean free path for secondary electrons as compared to layers that are located closer to the photoresist layer.
• a substrate 10 includes a photoresist layer 20 that is to be patterned.
• the photoresist layer 20 is deposited on a multi-layer stack 22.
• the multi-layer stack 22 includes a layer 24-1 having a first mean free path for secondary electrons and a layer 24-1 having a second mean path for secondary electrons that is different than the first mean free path.
• the multi-layer stack 22 is deposited on underlying substrate layers 32.
• the substrate 10 is exposed to EUV radiation reflected from a mask pattern.
• one or more additional steps may be performed to remove the exposed (or unexposed) photoresist layer and/or portions of the multi-layer stack located in areas where the photoresist layer is removed. Additional processing such as deposition and/or etching can be performed using the patterned photoresist layer 20. After the additional processing is performed, the photoresist layer 20 and the multi-layer stack 22 are removed.
• N secondary electron generating layers 24-N can be used where N is an integer greater than one.
• the method 100 includes depositing a first layer of multi-layer stack 22 with the longest mean free path for secondary electrons on the underlying substrate 32 at 110.
• N-1 additional layers are deposited on the first layer of the multi-layer stack 22.
• the N-1 additional layers have different mean free paths for secondary electrons than the first layer.
• successive deposited layers of the multi-layer stack 22 have a lower mean free path than preceding deposited layers of the multi-layer stack 22.
• the photoresist layer 20 is deposited on the multi-layer stack 22.
• selected portions of the photoresist layer are exposed using EUV light and further processing is performed as described above.
• the layer that is farthest from the photoresist layer 20 produces secondary electrons with the longest mean free path.
• the mean free paths of the other layers in the multi-layer stack 22 are then targeted so that they converge at approximately the same depth in the photoresist layer 20.
• the dose that is required can be reduced by a factor of approximately 3.
• the mean free path of the secondary electrons in each layer is controlled by selecting different materials for the corresponding layers. For example, materials having different absorption can be used. Highly absorbing materials tend to have shorter mean free paths.
• the multi-layer stack 22 includes a highly absorbing layer at the top of the multi-layer stack 22 and gradually lower absorbing layers towards the bottom of the multi-layer stack.
• a substrate 200 includes a photoresist layer 20 that is to be patterned.
• the photoresist layer 20 is deposited on a layer 210 having a mean free path that varies with depth. In some examples, the mean free path increases continuously, monotonically or in steps as a vertical distance from the photoresist layer 20 increases.
• the substrate 200 is exposed to EUV radiation reflected from the mask pattern. In some examples, one or more additional steps may be performed to remove the exposed (or unexposed) photoresist and/or the layer 210 that is located in areas where the photoresist layer 20 is removed. Additional processing such as deposition and/or etching can be performed using the photoresist layer 20 that was patterned. After the additional processing is performed, the photoresist layer 20 and the layer 210 are removed.
• the mean free path can increase with the distance (linearly, monotonically, in steps, etc.).
• the mean free path increases linearly with the distance.
• the mean free path increases in steps as a function of the distance to the photoresist layer.
• a method 300 for patterning a substrate using the EUV photolithography, the photoresist layer 20 and the layer 210 with varying mean free paths is shown.
• the method 300 includes depositing the layer 20 with varying mean free paths for secondary electrons on underlying substrate layers 32 at 310.
• the photoresist layer 20 is deposited on the layer 210.
• selected portions of the photoresist layer 20 are exposed using EUV light and further processing is performed as described above.
• the amount of the localized dose increase can also be modified by scaling the mean free path of all layers.
• the secondary electrons’ inelastic mean free path is a function of electron energy, which results in a finite secondary electron density that can penetrate the photoresist.
• IMFP inelastic mean free path
• a multi-layer film can be developed where, within a critical range of electron energies, the film exhibits a longer IMFP for secondary electrons that are generated further from the photoresist.
• Layers that are farther from the photoresist produce secondary electrons with higher mean free paths (within the critical range of electron energies that can lead to the desired chemical reactions in the photoresist).
• Layers that are closer to the photoresist produce secondary electrons lower mean free paths (within the critical range of electron energies that can lead to the desired chemical reactions in the photoresist).
• the number of generated secondary electrons that reach the photoresist are expected to increase as a result of the arrangement of the multi-layer stack.
• One potential property for modifying the mean free path is to change the film density. Higher density is expected to lead to shorter mean free paths, so a potential stack consists of a higher density film at the top with gradually lower density films towards the bottom of the multilayer stack.
• the multilayer film is also not restricted to separate materials and may be a single material with a gradient.
• the thickness of the photoresist within which a significant change in effective dose is achieved can be modified by scaling the IMFP of all layers. Material examples are shown in the table below.
• the thickness of each layer can be the same or different.
• the total thickness of the multilayer stack may not exceed a predetermined thickness (e.g., 10 nm).
• a predetermined thickness e.g. 10 nm.
• the layers are arranged in monotonically increasing order of thickness from the top of the stack to the bottom of the stack.
• the thinnest layer is arranged at the top of the stack directly below the photoresist, and the thickest layer is arranged at the bottom of the stack directly above the substrate.
• the multilayer stack may include 2-4 layers, and the total thickness of the multilayer stack may be 5 nm.
• the multilayer stack may include 2 layers each having a thickness of 2.5 nm.
• the multilayer stack may include 4 layers each having a thickness of 1.25 nm.
• the multilayer stack may include 2 layers: one layer having a thickness of 2 nm arranged directly below the photoresist layer and another layer having a thickness of 3 nm arranged directly below the 2 nm layer and directly above the substrate.
• the multilayer stack may include 2-4 layers, and the total thickness of the multilayer stack may be 10 nm.
• the multilayer stack may include 2 layers each having a thickness of 5 nm.
• the multilayer stack may include 4 layers each having a thickness of 2.5 nm.
• the multilayer stack may include 2 layers: one layer having a thickness of 4 nm arranged directly below the photoresist layer and another layer having a thickness of 6 nm arranged directly below the 2 nm layer and directly above the substrate.
• the multilayer stack may include 3 layers: a first layer having a thickness of 2 nm, which is arranged directly below the photoresist layer, a second layer having a thickness of 3 nm arranged directly below the first layer, a third layer having a thickness of 5 nm arranged directly below the 3 nm layer and directly above the substrate.
• a first layer having a thickness of 2 nm which is arranged directly below the photoresist layer
• a second layer having a thickness of 3 nm arranged directly below the first layer
• a third layer having a thickness of 5 nm arranged directly below the 3 nm layer and directly above the substrate.
• Various other examples are contemplated.
• the thickness of the single layer with varying mean free paths may not exceed a predetermined thickness (e.g., 10 nm). Further, in either configuration, the thickness of the photoresist layer may be between 20 nm and 40 nm, for example.
• the methods of the present disclosure reduce the EUV dose by about 10%, which translates into significant cost savings.
• the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean“at least one of A, at least one of B, and at least one of C.”

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• Physics & Mathematics (AREA)
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• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Structural Engineering (AREA)
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• Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
• Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
• Materials For Photolithography (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)

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• 2020
  • 2020-05-15 CN CN202080036400.1A patent/CN113924528B/zh active Active
  • 2020-05-15 JP JP2021568218A patent/JP7840155B2/ja active Active
  • 2020-05-15 KR KR1020217040346A patent/KR102795783B1/ko active Active
  • 2020-05-15 TW TW109116186A patent/TWI842899B/zh active
  • 2020-05-15 US US17/595,062 patent/US12372872B2/en active Active
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