Photomask and method for manufacturing the same

Abstract

A photomask and a manufacturing method thereof, wherein the manufacturing method comprises: providing a transparent substrate, the transparent substrate comprising a first surface and a second surface opposite to the first surface; forming a plurality of discrete shielding patterns on the first surface of the transparent substrate; and forming linear microlenses on the second surface of the transparent substrate between the adjacent shielding patterns, the linear microlenses being used to converge more exposure light rays incident from the second surface to the first surface of the transparent substrate between the adjacent shielding patterns. When exposure is performed using the photomask of the present application, the linear microlenses can converge more exposure light rays incident from the second surface to the first surface of the transparent substrate between the adjacent shielding patterns (or to the light transmission region between the shielding patterns), thus improving the photosensitivity of the light transmission region and the resolution during photolithography.

Description

Technical Field

[0001] This application relates to the field of photomasks, and more particularly to a photomask and a method for manufacturing the same. Background Technology

[0002] Photolithography is an indispensable and crucial technology in integrated circuit manufacturing. The photolithography process typically includes the following steps: first, a photoresist or other photosensitive material is coated onto the wafer surface; after the photoresist material dries, a mask pattern on a photomask is exposed onto the photoresist photosensitive material using a specific light source through an exposure machine; subsequently, the photoresist photosensitive material is developed with a developer, forming a photoresist pattern on the wafer surface. This photoresist pattern serves as a mask pattern in subsequent ion implantation or etching processes.

[0003] Existing photomasks generally include: a transparent substrate; a plurality of discrete masking patterns (or masking patterns) formed on the surface of the transparent substrate; an annular frame on the surface of the transparent substrate, the annular frame surrounding the masking patterns; and a protective film on the top surface of the annular frame, the protective film and the annular frame being used to seal the photomask.

[0004] However, when using existing photomasks for exposure, the resolution still needs to be improved. Summary of the Invention

[0005] Some embodiments of this application provide a method for fabricating a photomask, including: A transparent substrate is provided, the transparent substrate including a first surface and a second surface opposite to the first surface; Multiple discrete masking patterns are formed on the first surface of the transparent substrate; Linear microlenses are formed on the second surface of a transparent substrate between the adjacent masking patterns. These linear microlenses are used to focus more of the exposure light incident from the second surface onto the first surface of the transparent substrate between the adjacent masking patterns.

[0006] In some embodiments, the linear microlens is larger than the spacing between adjacent masking patterns, and the linear microlens extends on the second surface along the extension direction of the adjacent masking patterns on the first surface.

[0007] In some embodiments, the linear microlenses converge the exposure light onto a first surface of a transparent substrate between adjacent masking patterns, and the size of the light is equal to the spacing between the adjacent masking patterns.

[0008] In some embodiments, the method for forming the linear microlens includes laser processing, photoresist hot melting, electric field induced rheoforming, confined micropore electrowetting, or ion exchange.

[0009] In some embodiments, the method further includes: etching a first surface of the transparent substrate to form a plurality of discrete annular trenches in the transparent substrate; The annular groove is filled with opaque material to form an annular deep groove structure; the masking pattern is located on the first surface of the transparent substrate in the middle of the annular deep groove structure and on the surface of the annular deep groove structure.

[0010] In some embodiments, the annular deep trench structure has an outwardly inclined outer wall, the surface of which coincides with the outermost optical path of the exposure light converged by the linear microlens, and the bottom edge of the masking pattern is flush with the edge of the top surface of the annular deep trench structure.

[0011] In some embodiments, the masking pattern is formed after the deep trench structure, or the masking pattern is formed simultaneously with the annular deep trench structure.

[0012] In some embodiments, when the masking pattern is formed after the deep trench structure, the formation process of the deep trench structure and the masking pattern includes: forming a patterned first mask layer on the surface of the transparent substrate, the patterned first mask layer having a plurality of discrete annular first openings exposing a portion of the surface of the transparent substrate; using the patterned first mask layer as a mask, etching the transparent substrate along the annular first openings to form a plurality of discrete annular trenches in the transparent substrate; removing the patterned first mask layer; forming an opaque material film on the surface of the annular trenches and the transparent substrate; and removing the opaque material film from the surface of the transparent substrate using a chemical mechanical polishing process. A thin film is formed in the annular trench to create an annular deep trench structure; a masking pattern film is formed on the surface of the transparent substrate and the surface of the annular deep trench structure; a patterned second mask layer is formed on the surface of the masking pattern film, the patterned second mask layer covering the surface of the masking pattern film on the surface of the transparent substrate in the middle of the annular deep trench structure and on the surface of the annular deep trench structure, exposing the surface of the masking pattern film in other areas; using the patterned second mask layer as a mask, the masking pattern film is etched to form a masking pattern on the surface of the transparent substrate in the middle of the annular deep trench structure and on the surface of the annular deep trench structure; the patterned second mask layer is then removed.

[0013] In some embodiments, when the masking pattern and the annular deep trench structure are formed simultaneously, the formation process of the deep trench structure and the masking pattern includes: forming a patterned first mask layer on the surface of the transparent substrate, the patterned first mask layer having a plurality of discrete annular first openings exposing a portion of the surface of the transparent substrate; using the patterned first mask layer as a mask, etching the transparent substrate along the annular first openings to form a plurality of discrete annular trenches in the transparent substrate; removing the patterned first mask layer; forming an opaque material film on the surface of the annular trenches and the transparent substrate; and using a chemical mechanical polishing process. The surface of the opaque material film is planarized; a patterned second mask layer is formed on the planarized surface of the opaque material film, the patterned second mask layer covering the surface of the transparent substrate in the middle of the annular trench and the surface of the opaque material film on the annular trench, exposing the surface of the opaque material film in other areas; using the patterned second mask layer as a mask, the opaque material film is etched to form an annular deep trench structure in the annular trench, and a masking pattern is formed on the surface of the transparent substrate in the middle of the annular deep trench structure and on the surface of the annular deep trench structure; the patterned second mask layer is removed.

[0014] In some embodiments, the deep trench structure is used to prevent exposed light from being scattered and / or refracted at the periphery of the masking pattern and then moving or spreading to the opaque area at the bottom of the masking pattern.

[0015] Some embodiments of this application also provide a photomask, including: A transparent substrate, the transparent substrate including a first surface and a second surface opposite to the first surface; Multiple discrete masking patterns located on the first surface of the transparent substrate; A linear microlens is located on the second surface of a transparent substrate between the adjacent masking patterns. The linear microlens is used to focus more of the exposure light incident from the second surface onto the first surface of the transparent substrate between the adjacent masking patterns.

[0016] In some embodiments, the linear microlens is larger than the spacing between adjacent masking patterns, and the linear microlens extends on the second surface along the extension direction of the adjacent masking patterns on the first surface.

[0017] In some embodiments, the linear microlenses converge the exposure light onto a first surface of a transparent substrate between adjacent masking patterns, and the size of the light is equal to the spacing between the adjacent masking patterns.

[0018] In some embodiments, the method further includes: a plurality of discrete annular grooves penetrating a first surface of the transparent substrate and located in the transparent substrate; an annular deep trench structure filling the annular grooves; and the masking pattern located on the first surface of the transparent substrate in the middle of the annular deep trench structure and on the surface of the annular deep trench structure.

[0019] In some embodiments, the annular deep trench structure has an outwardly inclined outer wall, the surface of which coincides with the outermost optical path of the exposure light converged by the linear microlens, and the bottom edge of the masking pattern is flush with the edge of the top surface of the annular deep trench structure.

[0020] The photomask fabrication method of some embodiments of this application provides a transparent substrate, the transparent substrate including a first surface and a second surface opposite to the first surface, and then forming a plurality of discrete masking patterns on the first surface of the transparent substrate; a linear microlens is formed on the second surface of the transparent substrate between adjacent masking patterns, the linear microlens being used to converge more of the exposure light incident from the second surface onto the first surface of the transparent substrate between adjacent masking patterns. When exposure is performed using the photomask of this application, the linear microlenses can converge more of the exposure light incident from the second surface onto the first surface of the transparent substrate between adjacent masking patterns (or converge it into the light-transmitting area between the masking patterns), thereby increasing the photosensitivity of the light-transmitting area and thus improving the resolution during photolithography.

[0021] Furthermore, the bottom edge of the formed masking pattern is flush with the edge of the top surface of the annular deep trench structure. The annular deep trench structure has an outwardly inclined outer wall. The surface of the outer wall of the annular deep trench structure coincides with the outermost optical path of the exposure light converged by the subsequently formed linear microlenses. This allows the annular deep trench structure to prevent the exposure light from being scattered and / or refracted at the edges of the formed masking pattern and then moving or diffusing into the opaque area at the bottom of the masking pattern. In other words, the deep trench structure can confine the exposure light within the light-transmitting area between adjacent masking patterns, preventing the exposure light from reaching or diffusing into the opaque area at the bottom of the masking pattern due to scattering and / or refraction at the edges of the masking pattern. This improves the positional and dimensional accuracy of the photolithographic pattern formed in the photoresist layer after exposure (using the photomask of this application for exposure) and maintains a better sidewall morphology. At the same time, the formed deep trench structure does not block the exposure light converged by the subsequently formed linear microlenses, improving the photosensitivity of the light-transmitting area and thus improving the resolution during photolithography. Attached Figure Description

[0022] Figures 1-7This is a schematic diagram of the photomask fabrication process in some embodiments of this application. Detailed Implementation

[0023] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. In describing the embodiments of this application in detail, for ease of explanation, the schematic diagrams may be partially enlarged without adhering to the general scale, and the schematic diagrams are merely examples and should not limit the scope of protection of this application. Furthermore, in actual manufacturing, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0024] This application first provides a method for fabricating a photomask, and the photomask fabrication process will be described in detail below with reference to the accompanying drawings.

[0025] refer to Figure 1 A transparent substrate 201 is provided, the transparent substrate 201 including a first surface 11 and a second surface 12 opposite to the first surface 11.

[0026] The transparent substrate 201 serves as the carrier of the photomask. The transparent substrate 201 is made of a light-transmitting material with a light transmittance greater than 90%. In some embodiments, the material of the transparent substrate 201 can be quartz glass or soda glass. In other embodiments, the material of the transparent substrate 201 can also be fused silica, calcium fluoride, silicon nitride, titanium dioxide alloy, or sapphire. The transparent substrate 201 includes two opposing first surfaces 11 and second surfaces 12. A masking pattern and an annular frame are subsequently formed on the first surface 11. When the photomask of this application is used for exposure, the exposure light generated by the exposure light source is incident from the second surface 12 side. After being blocked by the masking pattern, part of the exposure light is emitted from the first surface 11 of the transparent substrate 201.

[0027] In some embodiments, the transparent substrate 201 may include a central region and an edge region surrounding the central region. The central region may be square, circular, or other suitable shapes, and the edge region may be annular, surrounding the central region. The central region may subsequently be used to form a masking pattern (or a masking pattern), and the central region may also be used to form a phase-shifting layer. The edge region may subsequently be used to form an annular frame.

[0028] In some embodiments, it also includes: reference Figure 2 The first surface 11 of the transparent substrate 201 is etched to form a plurality of discrete annular grooves 207 in the transparent substrate 201.

[0029] The annular groove 207 is subsequently used to form a deep groove structure. The number of the annular groove 207 is at least one.

[0030] The annular trench 207 has an outwardly inclined outer wall. The inclination angle of the outer wall (the angle between the outer wall and the second surface 12 of the transparent substrate 201) is greater than or equal to the incident angle of the outermost optical path of the exposure light converged by the subsequently formed linear microlenses (the incident angle is the angle between the outermost optical path of the exposure light converged by the linear microlenses and the second surface 12 of the transparent substrate 201). This ensures that after the annular deep trench structure is subsequently formed in the annular deep trench, the annular deep trench structure also has an outwardly inclined outer wall. The surface of the outer wall of the annular deep trench structure coincides with or is located outside the outermost optical path of the exposure light converged by the subsequently formed linear microlenses. The annular deep trench structure prevents the exposed light from being scattered and / or refracted at the edges of the subsequently formed masking pattern, thus preventing it from moving or diffusing into the opaque area at the bottom of the masking pattern. In other words, the deep trench structure confines the exposed light to the light-transmitting area between adjacent masking patterns, preventing the exposed light from reaching or diffusing into the opaque area at the bottom of the masking pattern due to scattering and / or refraction at the edges of the masking pattern. This improves the positional and dimensional accuracy of the photolithographic pattern formed in the photoresist layer after exposure (using the photomask of this application) and maintains a better sidewall morphology. At the same time, the formed deep trench structure does not block the exposed light converged by the linear microlenses, improving the photosensitivity of the light-transmitting area and thus improving the resolution during photolithography.

[0031] The annular groove 207 is annular in shape, and the outer wall shape of the annulus is the same as the side wall shape of the subsequently formed masking pattern. In some embodiments, the annulus includes a square annulus, a rectangular annulus, a polygonal annulus (with more than 4 sides), or other regular or irregular patterned annulus.

[0032] In some embodiments, the depth of the annular trench 207 is 500nm-2.5um, the width of the annular trench 207 is smaller than the width of the subsequently formed masking pattern, and the width of the annular trench 207 is 10nm-300nm.

[0033] In some embodiments, before forming the annular trench 207, a patterned first mask layer (not shown) is formed on the first surface 11 of the transparent substrate 201. The patterned first mask layer has a plurality of discrete annular first openings that expose a portion of the first surface 11 of the transparent substrate 201. Using the patterned first mask layer as a mask, the transparent substrate 201 is etched along the annular first openings to form a plurality of discrete annular trenches in the transparent substrate 201. The patterned first mask layer is then removed.

[0034] The transparent substrate 201 can be etched using either a dry etching process or a wet etching process.

[0035] refer to Figure 3 and Figure 4 In the annular groove 207 (reference) Figure 2 The interior is filled with opaque material to form an annular deep groove structure 209 (reference). Figure 4 ); a masking pattern 202 is formed on the surface of the transparent substrate 201 in the middle of the annular deep trench structure 209 and on the surface of the annular deep trench structure 209 (see reference). Figure 4 ).

[0036] In this embodiment, the bottom edge of the formed masking pattern 201 is flush with the edge of the top surface of the annular deep trench structure 209, that is, the bottom edge of the formed masking pattern 201 coincides with the edge of the top surface of the annular deep trench structure 209. In other embodiments, the bottom edge of the formed masking pattern 201 may also protrude to both sides beyond the edge of the top surface of the annular deep trench structure 209. Furthermore, in some embodiments, the annular deep trench structure 209 may have outwardly inclined outer walls, the surface of which coincides with or is located outside the outermost optical path of the exposure light converged by the subsequently formed linear microlens, such that the annular deep trench structure 209 can prevent the exposure light from being scattered and / or refracted at the edges of the formed masking pattern 202 and then moving or diffusing towards the opaque area at the bottom of the masking pattern 202, i.e., the deep trench structure 209 can divert the exposure light... The linear constraint within the light-transmitting area between adjacent masking patterns 202 prevents the exposure light from reaching or diffusing into the opaque area at the bottom of the masking pattern 202 due to scattering and / or refraction at the edge of the masking pattern 202. This improves the positional and dimensional accuracy of the photolithographic pattern formed in the photoresist layer after exposure (using the photomask of this application for exposure) and maintains a good sidewall morphology. At the same time, the formed deep trench structure 209 does not block the exposure light converged by the subsequently formed linear microlenses, improving the photosensitivity of the light-transmitting area and thus improving the resolution during photolithography.

[0037] In this embodiment, the masking pattern 202 and the annular deep trench structure 209 are formed simultaneously to save process steps.

[0038] In some embodiments, when the masking pattern 202 and the annular deep trench structure 209 are formed simultaneously, the formation process of the deep trench structure 209 and the masking pattern 202 includes: first forming a plurality of discrete annular trenches 207 in the transparent substrate 201 (see reference). Figure 2); An opaque material film 208 (reference) is formed on the surface of the annular groove and the transparent substrate. Figure 3 The surface of the opaque material film 208 is planarized using a chemical mechanical polishing process, resulting in a flat surface. A patterned second mask layer (not shown in the figure) is formed on the planarized surface of the opaque material film 208. The patterned second mask layer covers the surface of the transparent substrate in the middle of the annular trench and the surface of the opaque material film 208 in the annular trench, exposing the surface of the opaque material film 208 in other areas. Using the patterned second mask layer as a mask, the opaque material film 208 is etched to form an annular deep trench structure 209 in the annular trench 207. A masking pattern 202 is formed on the surface of the transparent substrate 201 in the middle of the annular deep trench structure 209 and on the surface of the annular deep trench structure 209. The patterned second mask layer is then removed. The masking pattern 202 is formed simultaneously with the annular deep trench structure 209, which not only simplifies the process steps, but also, since the masking pattern 202 and the annular deep trench structure 209 are an integral structure, the masking pattern 202 and the annular deep trench structure 209 are more firmly bonded, making it less likely for the masking pattern 202 to detach from the surface of the transparent substrate 201 or to deform.

[0039] In this embodiment, the masking pattern 202 and the annular deep trench structure 209 are made of the same material. The material of the masking pattern 202 and the annular deep trench structure 209 is one or more of chromium, nickel, aluminum, ruthenium, molybdenum, titanium, tantalum, copper, tungsten, silver, and platinum, or one or more of chromium, nickel, aluminum, ruthenium, molybdenum, titanium, tantalum, copper, tungsten, silver, platinum, chromium oxide, iron oxide, niobium oxide, chromium nitride, molybdenum trioxide, molybdenum nitride, chromium oxide, titanium nitride, zirconium nitride, titanium oxide, tantalum nitride, tantalum oxide, silicon dioxide, niobium nitride, silicon nitride, silicon oxynitride, amorphous carbon, silicon carbide, neutral alumina, and alumina.

[0040] In some embodiments, the depth of the bottom of the annular deep trench structure 209 is 500nm-2.5um, and the width of the annular deep trench structure 209 is smaller than the width of the formed masking pattern 202. The width of the annular deep trench structure 209 is 10nm-300nm, which allows the deep trench structure 209 to better confine the exposure light within the light-transmitting area between adjacent masking patterns 202, and to better prevent the exposure light from reaching or diffusing into the opaque area at the bottom of the masking pattern 202 due to scattering and / or refraction at the edge of the masking pattern 202.

[0041] In some embodiments, the masking pattern 202 is formed after the deep trench structure 209. The formation process of the deep trench structure 209 and the masking pattern 202 includes: forming a patterned first mask layer (not shown) on the surface of the transparent substrate 201, the patterned first mask layer having a plurality of discrete annular first openings exposing a portion of the surface of the transparent substrate 201; using the patterned first mask layer as a mask, etching the transparent substrate 201 along the annular first openings to form a plurality of discrete annular trenches 207 (see reference) in the transparent substrate 201. Figure 2 The process involves: removing the patterned first mask layer; forming an opaque material film on the surfaces of the annular trench 207 and the transparent substrate 201; removing the opaque material film from the surface of the transparent substrate 201 using a chemical mechanical polishing process, forming an annular deep trench structure 209 in the annular trench 207; forming a masking pattern film on the surface of the transparent substrate 201 and the surface of the annular deep trench structure 209; forming a patterned second mask layer on the surface of the masking pattern film, the patterned second mask layer covering the surface of the masking pattern film on the surface of the transparent substrate 201 in the middle of the annular deep trench structure 209 and on the surface of the annular deep trench structure 209, exposing the surface of the masking pattern film in other areas; using the patterned second mask layer as a mask, etching the masking pattern film to form a masking pattern 202 on the surface of the transparent substrate 201 in the middle of the annular deep trench structure 209 and on the surface of the annular deep trench structure 209; and removing the patterned second mask layer.

[0042] The masking pattern 202 may be made of the same material as or different from the annular deep trench structure 209. The material of the masking pattern 202 (or the annular deep trench structure 209) is one or more of chromium, nickel, aluminum, ruthenium, molybdenum, titanium, tantalum, copper, tungsten, silver, and platinum, or one or more of chromium, nickel, aluminum, ruthenium, molybdenum, titanium, tantalum, copper, tungsten, silver, platinum, chromium oxide, iron oxide, niobium oxide, chromium nitride, molybdenum trioxide, molybdenum nitride, chromium oxide, titanium nitride, zirconium nitride, titanium oxide, tantalum nitride, tantalum oxide, silicon dioxide, niobium nitride, silicon nitride, silicon oxynitride, amorphous carbon, silicon carbide, neutral alumina, and alumina.

[0043] In some embodiments, after forming the masking pattern 202, a phase-shifting layer is formed on the first surface 11 of the transparent substrate 201 between the masking patterns 202. The phase-shifting layer is used to change the phase of the exposure light incident on the substrate to improve the resolution during exposure. The material of the phase-shifting layer is MoSi or MoSiON.

[0044] refer to Figure 5 and Figure 6 , Figure 6 for Figure 5 A bottom view of the middle part of the structure shows that a linear microlens 205 is formed on the second surface 12 of the transparent substrate 201 between the adjacent shielding patterns 202. The linear microlens 205 is used to converge more of the exposure light incident from the second surface 12 onto the first surface 11 of the transparent substrate 201 between the adjacent shielding patterns 202.

[0045] The linear microlens 205 is linear or strip-shaped, has an upwardly convex surface, and its cross-section is convex. Therefore, when using the photomask of this application for exposure, the linear microlens 205 can concentrate more of the exposure light incident from the second surface 12 onto the first surface 11 of the transparent substrate 201 between adjacent masking patterns 202 (or concentrate it into the light-transmitting area between the masking patterns 202), thereby improving the photosensitivity of the light-transmitting area and thus improving the resolution during photolithography.

[0046] In one embodiment, the dimension D1 of the linear microlens 205 is larger than the spacing D2 between adjacent masking patterns 202 (see reference). Figure 5 The linear microlens 205 extends on the second surface 12 along the extending direction Y of the adjacent shielding pattern 202 on the first surface 11 (see reference). Figure 6 The size of the exposure light converged by the linear microlens 205 onto the first surface 11 of the transparent substrate 201 between adjacent masking patterns 202 (the distance between the outermost optical path 13 of the exposure light converged by the linear microlens 205 and the bottom contact point of the two adjacent masking patterns 202) is equal to the spacing D2 between the adjacent masking patterns 202. This allows the linear microlens 205 to better converge more of the exposure light incident from the second surface 12 onto the first surface 11 of the transparent substrate 201 between adjacent masking patterns 202 (or converge it into the light-transmitting area between the masking patterns 202), and has little impact on the size of the exposure light after passing through the first surface 11 of the transparent substrate 201 between the two adjacent masking patterns 202. Therefore, while increasing the photosensitivity of the light-transmitting area of ​​the mask, there is no need to change the existing masking pattern 202 design on the photomask.

[0047] The linear microlens 205 is formed by laser processing, photoresist hot melting, electric field induced rheoforming, confined micropore electrowetting, or ion exchange.

[0048] In some embodiments, the linear microlens 205 is formed using a photoresist hot-melt method, the process including: spin-coating a photoresist layer of a specific thickness on the second surface of the transparent substrate 201; patterning the photoresist layer through exposure and development processes to form a patterned photoresist layer; and baking the patterned photoresist layer to form a pair of linear microlenses 205.

[0049] In some embodiments, reference Figure 7 It also includes: forming an annular frame 204 around the shielding pattern 202 on the surface of the edge region of the transparent substrate 201; and forming a protective film 206 on the top surface of the annular frame 204 to close the space inside the annular frame 204.

[0050] The annular frame 204 is used to support the protective film that is subsequently formed. The annular frame 204 and the protective film that are subsequently formed can isolate the masking pattern 202 on the photomask 201 and the surface of the middle area of ​​the photomask 201 from the external environment, preventing pollution from the external environment.

[0051] The annular frame 204 is a hollow ring, and the material of the annular frame 204 is a material with a certain mechanical strength. In some embodiments, the material of the annular frame 204 is aluminum. In other embodiments, the material of the annular frame 204 can be aluminum alloy, ceramic, carbon steel, or other suitable metallic or non-metallic materials.

[0052] In some embodiments, the annular frame 204 is adhered to the edge region of the transparent substrate by an adhesive layer 203.

[0053] The material of the adhesion layer 203 is an organic adhesive. In some embodiments, the organic adhesive is a rubber adhesive, a polyurethane adhesive, an acrylic adhesive, a SEBS (styrene-vinyl butene-styrene) adhesive, a SEPS (styrene-vinyl propylene-styrene) adhesive, or a siloxane adhesive.

[0054] The protective film 206 is made of a light-transmitting material.

[0055] Some embodiments of the present invention also provide a photomask, see reference. Figure 5 and Figure 6 ,include: A transparent substrate 201, the transparent substrate 201 including a first surface 11 and a second surface 12 opposite to the first surface 11; Multiple discrete masking patterns 202 located on the first surface 11 of the transparent substrate 201; A linear microlens 205 is located on the second surface 12 of the transparent substrate 201 between the adjacent masking patterns 202. The linear microlens 205 is used to focus more of the exposure light incident from the second surface 12 onto the first surface 21 of the transparent substrate 201 between the adjacent masking patterns 202.

[0056] In some embodiments, the size D1 of the linear microlens 205 is larger than the spacing D2 between adjacent masking patterns 202 (see reference). Figure 5 The linear microlens 205 extends on the second surface 11 along the extension direction of the adjacent shielding pattern 202 on the first surface 11 (see reference). Figure 6 ).

[0057] In some embodiments, reference Figure 5 It also includes: a plurality of discrete annular grooves penetrating the first surface of the transparent substrate and located in the transparent substrate; an annular deep trench structure 209 filling the annular grooves; and the masking pattern 202 located on the first surface 11 of the transparent substrate 201 in the middle of the annular deep trench structure 209 and on the surface of the annular deep trench structure 209.

[0058] In some embodiments, the size of the exposure light rays converged by the linear microlenses 205 onto the first surface 11 of the transparent substrate 201 between adjacent masking patterns 202 is equal to the spacing D2 between the adjacent masking patterns 202. The annular deep trench structure 209 has outwardly inclined outer walls, the surface of which coincides with the outermost optical path of the exposure light rays converged by the linear microlenses 205, and the bottom edge of the masking pattern 202 is flush with the edge of the top surface of the annular deep trench structure 209.

[0059] In some embodiments, the shading pattern 202 may be made of the same material as or different from the annular deep trench structure 209.

[0060] In some embodiments, the material of the masking pattern 202 or the annular deep trench structure 209 is one or more of chromium, nickel, aluminum, ruthenium, molybdenum, titanium, tantalum, copper, tungsten, silver, and platinum, or one or more of chromium, nickel, aluminum, ruthenium, molybdenum, titanium, tantalum, copper, tungsten, silver, platinum, chromium oxide, iron oxide, niobium oxide, chromium nitride, molybdenum trioxide, molybdenum nitride, chromium oxide, titanium nitride, zirconium nitride, titanium oxide, tantalum nitride, tantalum oxide, silicon dioxide, niobium nitride, silicon nitride, silicon oxynitride, amorphous carbon, silicon carbide, neutral alumina, and alumina.

[0061] In some embodiments, the depth of the annular trench is 500nm-2.5um and the width is 10nm-300nm.

[0062] In some embodiments, the deep trench structure 209 is used to prevent exposed light from being scattered and / or refracted at the periphery of the masking pattern and then moving or spreading to the opaque area at the bottom of the masking pattern.

[0063] In some embodiments, reference Figure 7 It also includes: an annular frame 204 surrounding the shielding pattern 202 on the surface of the edge region of the transparent substrate 201; and a protective film 206 on the top surface of the annular frame 204 that closes the space inside the annular frame 204.

[0064] It should be noted that the limitations or descriptions of the same or similar parts in some embodiments of the photomask of this application and some embodiments of the aforementioned photomask formation method will not be repeated here. For details, please refer to the limitations or descriptions of the corresponding parts in some embodiments of the aforementioned photomask formation method.

[0065] Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make possible changes and modifications to the technical solutions of this application by utilizing the methods and techniques disclosed above without departing from the spirit and scope of this application. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall fall within the protection scope of the technical solutions of this application.

Claims

1. A method for fabricating a photomask, characterized in that, include: A transparent substrate is provided, the transparent substrate including a first surface and a second surface opposite to the first surface; The first surface of the transparent substrate is etched to form a plurality of discrete annular trenches in the transparent substrate; The annular groove is filled with an opaque material to form an annular deep groove structure; Multiple discrete masking patterns are formed on the first surface of the transparent substrate, and the masking patterns are located on the first surface of the transparent substrate in the middle of the annular deep trench structure and on the surface of the annular deep trench structure. Linear microlenses are formed on the second surface of a transparent substrate between adjacent masking patterns. The linear microlenses are used to converge more of the exposure light incident from the second surface to the first surface of the transparent substrate between adjacent masking patterns. The annular deep trench structure has outwardly inclined outer walls. The surface of the outer walls coincides with the outermost optical path of the exposure light converged by the linear microlenses. The deep trench structure is used to prevent the exposure light from moving or diffusing to the opaque area at the bottom of the masking pattern after scattering and / or refraction at the periphery of the masking pattern.

2. The method for fabricating a photomask as described in claim 1, characterized in that, The linear microlens is larger than the spacing between adjacent masking patterns, and the linear microlens extends on the second surface along the extension direction of the adjacent masking patterns on the first surface.

3. The method for fabricating a photomask as described in claim 1 or 2, characterized in that, The linear microlenses converge the exposure light onto the first surface of the transparent substrate between adjacent masking patterns. The size of the light is equal to the spacing between the adjacent masking patterns.

4. The method for fabricating a photomask as described in claim 1, characterized in that, The methods for forming the linear microlenses include laser processing, photoresist hot melting, electric field induced rheoforming, confined micropore electrowetting, or ion exchange.

5. The method for fabricating a photomask as described in claim 1, characterized in that, The bottom edge of the masking pattern is flush with the edge of the top surface of the annular deep trench structure.

6. The method for fabricating a photomask as described in claim 1, characterized in that, The shading pattern is formed after the deep trench structure, or the shading pattern is formed simultaneously with the annular deep trench structure.

7. The method for fabricating a photomask as described in claim 6, characterized in that, When the masking pattern is formed after the deep trench structure, the formation process of the deep trench structure and the masking pattern includes: forming a patterned first mask layer on the surface of the transparent substrate, the patterned first mask layer having a plurality of discrete annular first openings exposing a portion of the surface of the transparent substrate; using the patterned first mask layer as a mask, etching the transparent substrate along the annular first openings to form a plurality of discrete annular trenches in the transparent substrate; removing the patterned first mask layer; forming an opaque material film on the surface of the annular trenches and the transparent substrate; and removing the opaque material film on the surface of the transparent substrate using a chemical mechanical polishing process. An annular deep trench structure is formed in the annular trench; a masking pattern film is formed on the surface of the transparent substrate and the surface of the annular deep trench structure; a patterned second mask layer is formed on the surface of the masking pattern film, the patterned second mask layer covering the surface of the masking pattern film on the surface of the transparent substrate in the middle of the annular deep trench structure and on the surface of the annular deep trench structure, exposing the surface of the masking pattern film in other areas; using the patterned second mask layer as a mask, the masking pattern film is etched to form a masking pattern on the surface of the transparent substrate in the middle of the annular deep trench structure and on the surface of the annular deep trench structure; the patterned second mask layer is removed.

8. The method for fabricating a photomask as described in claim 6, characterized in that, When the masking pattern and the annular deep trench structure are formed simultaneously, the formation process of the deep trench structure and the masking pattern includes: forming a patterned first mask layer on the surface of the transparent substrate, the patterned first mask layer having a plurality of discrete annular first openings exposing a portion of the surface of the transparent substrate; using the patterned first mask layer as a mask, etching the transparent substrate along the annular first openings to form a plurality of discrete annular trenches in the transparent substrate; removing the patterned first mask layer; forming an opaque material film on the surface of the annular trenches and the transparent substrate; and planarizing using a chemical mechanical polishing process. The surface of the opaque material film; a patterned second mask layer is formed on the planarized surface of the opaque material film, the patterned second mask layer covering the surface of the transparent substrate in the middle of the annular trench and the surface of the opaque material film on the annular trench, exposing the surface of the opaque material film in other areas; using the patterned second mask layer as a mask, the opaque material film is etched to form an annular deep trench structure in the annular trench, and a masking pattern is formed on the surface of the transparent substrate in the middle of the annular deep trench structure and on the surface of the annular deep trench structure; the patterned second mask layer is removed.

9. A photomask, characterized in that, include: A transparent substrate, the transparent substrate including a first surface and a second surface opposite to the first surface; Multiple discrete masking patterns located on the first surface of the transparent substrate; A linear microlens is located on the second surface of a transparent substrate between adjacent masking patterns. The linear microlens is used to focus more of the exposure light incident from the second surface onto the first surface of the transparent substrate between adjacent masking patterns. It also includes: a plurality of discrete annular grooves penetrating the first surface of the transparent substrate and located in the transparent substrate; an annular deep trench structure filled with an opaque material; the masking pattern located on the first surface of the transparent substrate and the surface of the annular deep trench structure in the middle of the annular deep trench structure, the annular deep trench structure having an outwardly inclined outer sidewall, the surface of the outer sidewall coinciding with the outermost optical path of the exposure light converged by the linear microlens, the deep trench structure being used to prevent the exposure light from moving or diffusing to the opaque area at the bottom of the masking pattern after being scattered and / or refracted at the periphery of the masking pattern.

10. The photomask as described in claim 9, characterized in that, The linear microlens is larger than the spacing between adjacent masking patterns, and the linear microlens extends on the second surface along the extension direction of the adjacent masking patterns on the first surface.

11. The photomask as described in claim 9 or 10, characterized in that, The linear microlenses converge the exposure light onto the first surface of the transparent substrate between adjacent masking patterns. The size of the light is equal to the spacing between the adjacent masking patterns.

12. The photomask as described in claim 9, characterized in that, The bottom edge of the masking pattern is flush with the edge of the top surface of the annular deep trench structure.

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