Mask structure and method of forming the same

Abstract

The present disclosure relates to the technical field of semiconductor technology, and discloses a mask structure and a forming method thereof. The forming method comprises: forming a to-be-patterned film layer, a first mask layer, a light-blocking layer and a first photoresist layer which are sequentially stacked and distributed; forming a first developing area in the first photoresist layer; etching the light-blocking layer in the first developing area to form a first mask pattern exposing the first mask layer; etching the first mask layer exposed in the first mask pattern to form a plurality of second mask patterns which are spaced apart; and etching the to-be-patterned film layer with the second mask pattern as a mask to form a target mask pattern, wherein an etching selection ratio of the first mask layer to the to-be-patterned film layer is greater than an etching selection ratio of the light-blocking layer to the to-be-patterned film layer. The forming method of the present disclosure can improve the resolution of the mask pattern.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and more specifically, to a mask structure and a method for forming the same. Background Technology

[0002] Photomasks are one of the commonly used auxiliary structures in semiconductor manufacturing processes. However, during the formation of mask patterns in photomasks, the resolution of the formed mask patterns is relatively low due to the influence of the manufacturing process.

[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] In view of this, the present disclosure provides a mask structure and a method for forming the same, which can improve the resolution of the mask pattern.

[0005] According to one aspect of this disclosure, a method for forming a mask structure is provided, comprising:

[0006] The patterned film layer, the first mask layer, the light-shielding layer, and the first photoresist layer are formed in sequence and stacked.

[0007] A first development area is formed within the first photoresist layer;

[0008] The light-shielding layer is etched in the first developing area to form a first mask pattern that exposes the first mask layer;

[0009] The first mask layer exposed within the first mask pattern is etched to form a plurality of spaced second mask patterns;

[0010] The second mask pattern is used as a mask to etch the film layer to be patterned to form a target mask pattern. The etching selectivity ratio between the first mask layer and the film layer to be patterned is greater than the etching selectivity ratio between the light-shielding layer and the film layer to be patterned.

[0011] In one exemplary embodiment of this disclosure, before forming the first photoresist layer, the formation method further includes:

[0012] A second mask layer is formed on the surface of the light-shielding layer, and the first photoresist layer is located on the surface of the second mask layer;

[0013] Etching the light-shielding layer in the first developing area to form a first mask pattern exposing the first mask layer includes:

[0014] The second mask layer is etched in the first developing area to form an opening that exposes the light-shielding layer;

[0015] The light-shielding layer is etched at the opening to form a first mask pattern that exposes the first mask layer, wherein the etch selectivity ratio of the second mask layer to the patterned film layer is greater than the etch selectivity ratio of the light-shielding layer to the patterned film layer.

[0016] In an exemplary embodiment of this disclosure, the film layer to be patterned includes a central region and an edge region surrounding the outer periphery of the central region, the orthographic projection of the second mask pattern onto the film layer to be patterned is located in the central region, and the formation method further includes:

[0017] A second photoresist layer is formed on the side of the second mask layer away from the film layer to be patterned. The orthographic projection of the second photoresist layer on the film layer to be patterned is located in the edge region and coincides with the boundary of the edge region.

[0018] Remove the second mask layer and the light-shielding layer from the areas not covered by the second photoresist layer;

[0019] Remove the second photoresist layer.

[0020] In an exemplary embodiment of this disclosure, the film layer to be patterned includes a central region and an edge region surrounding the outer periphery of the central region. The orthographic projection of the first mask pattern onto the film layer to be patterned is located in the central region and coincides with the boundary of the central region. Etching the first mask layer exposed within the first mask pattern to form a plurality of spaced-apart second mask patterns includes:

[0021] A third photoresist layer is formed on the surface of the second mask layer away from the patterned film layer, and the third photoresist layer fills the first mask pattern.

[0022] Multiple spaced third developing regions are formed within the third photoresist layer, and the orthographic projection of the third developing region on the film layer to be patterned is located in the central region.

[0023] The first mask layer is etched in the third developing area to form the second mask pattern.

[0024] In one exemplary embodiment of this disclosure, the forming method further includes:

[0025] Remove the third photoresist layer.

[0026] In one exemplary embodiment of this disclosure, after forming the target mask pattern, the forming method further includes:

[0027] Remove the second mask layer located in the edge region and the remaining first mask layer on the surface of the central region.

[0028] In one exemplary embodiment of this disclosure, the thickness of the first mask layer is 2nm to 20nm, and the thickness of the photoresist layer is 50nm to 100nm.

[0029] In one exemplary embodiment of this disclosure, the first mask layer and the second mask layer are made of the same material.

[0030] In one exemplary embodiment of this disclosure, the material of the film layer to be patterned is a transparent material.

[0031] According to one aspect of this disclosure, a mask structure is provided, said mask structure being formed by the method for forming a mask structure as described in any one of the preceding claims.

[0032] The mask structure and its formation method disclosed herein can add a first mask layer between the film layer to be patterned and the light-shielding layer. Since the etch selectivity between the first mask layer and the film layer to be patterned is greater than that between the light-shielding layer and the film layer to be patterned, the etch selectivity between the first mask layer and the film layer to be patterned is relatively larger than that between the light-shielding layer. When etching the film layer to be patterned, the etching micro-load effect can be effectively reduced by setting the first mask layer, improving the etch depth-to-width ratio of the film layer to be patterned, which helps to more accurately transfer the second mask pattern into the film layer to be patterned, so as to obtain vertical sidewalls, thereby improving the resolution of the final target mask pattern.

[0033] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0035] Figure 1 This is a schematic diagram of the developing area in related technologies.

[0036] Figure 2 This is a schematic diagram of a mask pattern in related technologies.

[0037] Figure 3 This is a flowchart of the method for forming the mask structure in an embodiment of this disclosure.

[0038] Figure 4This is a schematic diagram of the patterned film layer, the first mask layer, the light-shielding layer, and the first photoresist layer in an embodiment of this disclosure.

[0039] Figure 5 This is a schematic diagram of the first developing area in one embodiment of the present disclosure.

[0040] Figure 6 This is a schematic diagram of the first developing area in another embodiment of the present disclosure.

[0041] Figure 7 This is a schematic diagram of the first mask pattern in one embodiment of the present disclosure.

[0042] Figure 8 This is a schematic diagram of the first mask pattern in another embodiment of the present disclosure.

[0043] Figure 9 This is a schematic diagram of the second mask pattern in one embodiment of the present disclosure.

[0044] Figure 10 This is a schematic diagram of the second mask pattern in another embodiment of the present disclosure.

[0045] Figure 11 This is a schematic diagram of a target mask pattern in one embodiment of the present disclosure.

[0046] Figure 12 This is a schematic diagram of a target mask pattern in another embodiment of the present disclosure.

[0047] Figure 13 This is a schematic diagram of the second mask layer in an embodiment of this disclosure.

[0048] Figure 14 This is a schematic diagram of an opening in one embodiment of the present disclosure.

[0049] Figure 15 This is a schematic diagram of an opening in another embodiment of the present disclosure.

[0050] Figure 16 This is a schematic diagram of the second photoresist material layer in an embodiment of this disclosure.

[0051] Figure 17 This is a schematic diagram of the second developing area in an embodiment of this disclosure.

[0052] Figure 18 This is a schematic diagram of the structure after step S330 is completed in an embodiment of this disclosure.

[0053] Figure 19 This is a schematic diagram of the third photoresist layer in an embodiment of this disclosure.

[0054] Figure 20 This is a schematic diagram of the third developing area in an embodiment of this disclosure.

[0055] Figure 21 This is a schematic diagram of the structure after step S170 is completed in an embodiment of this disclosure.

[0056] Explanation of reference numerals in the attached figures:

[0057] 100. Film layer to be etched; 10. Mask pattern; 200. Light-shielding layer; 300. Photoresist layer; 30. Developing area; 1. Film layer to be patterned; 101. Target mask pattern; 2. First mask layer; 201. Second mask pattern; 3. Light-shielding layer; 301. First mask pattern; 4. First photoresist layer; 401. First developing area; 5. Second mask layer; 501. Opening; 6. Second photoresist layer; 61. Second photoresist material layer; 7. Third photoresist layer; 71. Third developing area; A. Central region; B. Edge region. Detailed Implementation

[0058] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore detailed descriptions of them will be omitted. Furthermore, the drawings are merely illustrative of this disclosure and are not necessarily drawn to scale.

[0059] Although relative terms such as "up" and "down" are used in this specification to describe the relative relationship of one component of an icon to another, these terms are used only for convenience, such as according to the orientation of the examples shown in the accompanying drawings. It is understood that if the device of the icon is flipped upside down, the component described as "up" will become the component described as "down." When a structure is "up" of another structure, it may mean that the structure is integrally formed on the other structure, or that the structure is "directly" mounted on the other structure, or that the structure is "indirectly" mounted on the other structure through another structure.

[0060] The terms “a,” “one,” “the,” “the,” and “at least one” are used to indicate the presence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended inclusion and to mean that there may be other elements / components / etc. in addition to the listed elements / components / etc.; the terms “first,” “second,” and “third,” etc., are used only as markers and are not a limitation on the number of objects.

[0061] The fabrication process for forming a mask pattern in a photomask structure / mask mainly includes: forming a light-shielding layer 200 (the material of which can be chromium) and a photoresist layer 300 on the film layer 100 to be etched; exposing and developing the photoresist layer 300 to form the developing area 30 (e.g., Figure 1 (As shown); the light-shielding layer 200 and the film layer 100 to be etched are etched in the developing area 30, thereby forming a mask pattern 10 (as shown) in the film layer 100 to be etched. Figure 2 (As shown). In the above process, especially in the manufacturing process of a fully transparent, chromium-free alternating phase-shifting photomask, the thickness of the light-shielding layer 200 is often relatively thick to ensure the light-shielding effect. However, the thicker the light-shielding layer 200, the stronger the interaction between the light waves and the light-shielding layer 200. During the exposure of the photoresist layer 300, the optimal focus value shifts more with the pattern size, resulting in a lower resolution of the final mask pattern 10. Furthermore, the greater the thickness of the light-shielding layer 200, the thicker the photoresist layer 300 will also be, making it prone to photoresist collapse during development, leading to a lower product yield. In addition, during the etching of the film layer 100, the relatively thick light-shielding layer 200 results in a strong etching micro-load effect, further affecting the resolution of the mask pattern 10. Currently, the thickness of the light-shielding layer 200 has been reduced to the limit of opacity and cannot be further thinned. Therefore, a new process technology is needed to overcome this technological bottleneck.

[0062] Based on this, the present disclosure provides a method for forming a mask structure. Figure 3 A flowchart illustrating the method for forming the mask structure of this disclosure is shown; please refer to [link / reference]. Figure 3 As shown, the forming method includes steps S110-S150, wherein:

[0063] Step S110: Forming a patterned film layer, a first mask layer, a light-shielding layer and a first photoresist layer that are stacked in sequence;

[0064] Step S120: A first developing area is formed within the first photoresist layer;

[0065] Step S130: Etch the light-shielding layer in the first developing area to form a first mask pattern that exposes the first mask layer;

[0066] Step S140: Etch the first mask layer exposed within the first mask pattern to form a plurality of spaced second mask patterns;

[0067] Step S150: Using the second mask pattern as a mask, the film layer to be patterned is etched to form a target mask pattern. The etching selectivity ratio between the first mask layer and the film layer to be patterned is greater than the etching selectivity ratio between the light-shielding layer and the film layer to be patterned.

[0068] The method for forming a mask structure disclosed herein can add a first mask layer between the film layer to be patterned and the light-shielding layer. Since the etch selectivity between the first mask layer and the film layer to be patterned is greater than that between the light-shielding layer and the film layer to be patterned, the etch selectivity between the first mask layer and the film layer to be patterned is relatively larger than that between the light-shielding layer. When etching the film layer to be patterned, the etching micro-load effect can be effectively reduced by setting the first mask layer, improving the etch depth-to-width ratio of the film layer to be patterned, which helps to more accurately transfer the second mask pattern into the film layer to be patterned, so as to obtain vertical sidewalls, thereby improving the resolution of the final target mask pattern.

[0069] The following provides a detailed description of each step and specific details of the method for forming the mask structure disclosed herein:

[0070] like Figure 3 As shown, in step S110, a patterned film layer, a first mask layer, a light-shielding layer, and a first photoresist layer are formed in sequence.

[0071] like Figure 4 As shown, the material of the patterned film layer 1 can be a transparent material, such as quartz. In other embodiments, the material of the patterned film layer 1 can be a substrate used to prepare a fully transparent alternating phase mask. The patterned film layer 1 serves as a substrate, and a first mask layer 2 is formed on its surface by chemical vapor deposition, physical vapor deposition, or atomic layer deposition. Of course, the first mask layer 2 can also be formed by other methods, and no specific limitation is made here. In some embodiments of this disclosure, the material of the first mask layer 2 can be a material with a relatively high etch selectivity compared to the patterned film layer 1, such as chromium. The thickness of the first mask layer 2 is relatively small; for example, it can be 2 nm to 20 nm. For example, the thickness of the first mask layer 2 can be 2 nm, 5 nm, 10 nm, 15 nm, or 20 nm. Of course, the first mask layer 2 can also have other thicknesses, which will not be listed here.

[0072] In some embodiments of this disclosure, the patterned film layer 1 may include a central region A and an edge region B, wherein the central region A and the edge region B may be adjacent to each other, and the edge region B may surround the outer periphery of the central region A. For example, the central region A may be a circular region, an elliptical region, a rectangular region, or an irregularly shaped region; of course, it may also be a region of other shapes, without special limitation. The edge region B may be an annular region and may surround the outer periphery of the central region A; it may be a circular annular region, a rectangular annular region, or an annular region of other shapes, which will not be listed here.

[0073] The material of the light-shielding layer 3 can be a material with high optical density. For example, the optical density of the light-shielding layer 3 can be higher than that of the first mask layer 2. That is, under the premise of achieving the same optical density, the thickness of the light-shielding layer 3 is less than the thickness of the first mask layer 2. For example, the material of the light-shielding layer 3 can be molybdenum silicide. Compared with the traditional use of chromium as the material of the light-shielding layer 3, using molybdenum silicide with higher optical density as the light-shielding layer 3 requires only a very thin thickness to block light with a wavelength of 193nm. For example, experiments show that the optical density of a 47nm thick molybdenum silicide film and the optical density of a 73nm thick chromium film are both 3.1. That is, when achieving the same light-shielding effect, the thickness of the light-shielding layer 3, which uses molybdenum silicide as the main material in this application, is relatively small (36% less than the thickness of the chromium film). This results in a relatively small interaction between the light wave and the light-shielding layer 3 during the subsequent exposure of the first photoresist layer 4 on its surface, and a relatively smaller degree of shift in the optimal focus value with the pattern size. In some embodiments of this disclosure, the light-shielding layer 3 can be formed on the surface of the first mask layer 2 by means of chemical vapor deposition, physical vapor deposition or atomic layer deposition. Of course, the light-shielding layer 3 can also be formed by other means. No special limitation is made here on the formation method of the light-shielding layer 3.

[0074] A first photoresist layer 4 can be formed on the side of the light-shielding layer 3 facing away from the first mask layer 2. For example, the material of the first photoresist layer 4 can be photoresist, and it can be formed on the side of the light-shielding layer 3 facing away from the first mask layer 2 by spin coating or other methods. In this process, since the thickness of the light-shielding layer 3 is relatively small, the thickness of the first photoresist layer 4 can also be reduced accordingly, thereby avoiding photoresist collapse during the subsequent development process of the first photoresist layer 4, which helps to improve product yield. For example, the thickness of the first photoresist layer 4 is relatively small, for example, its thickness can be 50nm to 100nm, such as 50nm, 60nm, 70nm, 80nm, 90nm or 100nm. Of course, the first photoresist layer 4 can also have other thicknesses, which will not be listed here.

[0075] like Figure 3 As shown, in step S120, a first developing region 401 is formed in the first photoresist layer 4.

[0076] like Figure 5 and Figure 6As shown, the first photoresist layer 4 can be exposed and developed to form the first developed area 401. The number of first developed areas 401 can be one or more, without special limitation. The orthographic projection of the first developed area 401 onto the patterned film layer 1 can be located in the central region A. In the direction parallel to the first photoresist layer 4, the cross-section of the first developed area 401 can be circular, elliptical, rectangular, polygonal, or irregular; the shape of the first developed area 401 is not particularly limited here.

[0077] like Figure 3 As shown, in step S130, the light-shielding layer 3 is etched in the first developing area 401 to form a first mask pattern 301 that exposes the first mask layer 2.

[0078] like Figure 7 and Figure 8 As shown, the light-shielding layer 3 can be etched using a dry etching process to form a first mask pattern 301 within the light-shielding layer 3. The first mask pattern 301 can be a through-hole penetrating the light-shielding layer 3. The number of first mask patterns 301 is equal to the number of first developing areas 401. For example, when there is one first developing area 401, there is also one first mask pattern 301; when there are multiple first developing areas 401, there are also multiple first mask patterns 301. A first mask pattern 301 can be formed correspondingly below each first developing area 401.

[0079] In some embodiments of this disclosure, the material of the light-shielding layer 3 is molybdenum silicide. Since molybdenum silicide has good etching properties, it is easy to form a first mask pattern 301 with a good morphology.

[0080] like Figure 3 As shown, in step S140, the first mask layer 2 exposed in the first mask pattern 301 is etched to form a plurality of spaced second mask patterns 201.

[0081] like Figure 9 and Figure 10 As shown, the first mask layer 2 exposed by the first mask pattern 301 can be etched using a dry etching process, thereby forming multiple spaced second mask patterns 201 within the first mask layer 2. The orthographic projection of each second mask pattern 201 onto the patterned film layer 1 is located in the central region A. In the direction parallel to the first mask layer 2, the cross-section of the second mask pattern 201 can be circular, elliptical, rectangular, polygonal, or irregular in shape; no specific limitation is made on the specific shape of the second mask pattern 201 here.

[0082] like Figure 3As shown, in step S150, the film layer 1 to be patterned is etched using the second mask pattern 201 as a mask to form the target mask pattern 101. The etching selectivity ratio of the first mask layer 2 to the film layer 1 to be patterned is greater than the etching selectivity ratio of the light-shielding layer 3 to the film layer 1 to be patterned.

[0083] like Figure 11 and Figure 12 As shown, the second mask pattern 201 can be used as a mask for dry etching of the patterned film layer 1, thereby forming multiple spaced target mask patterns 101 within the patterned film layer 1. During the etching process of the patterned film layer 1, since the etch selectivity ratio between the first mask layer 2 and the patterned film layer 1 is relatively large, the etching micro-load effect can be effectively reduced by setting the first mask layer 2, improving the etch aspect ratio of the patterned film layer 1, and helping to more accurately transfer the second mask pattern 201 into the patterned film layer 1, so as to obtain vertical sidewalls, thereby improving the resolution of the final formed target mask pattern 101. At the same time, since the thickness of the first mask layer 2 is relatively small, it helps to further reduce the etching micro-load effect and further improve the resolution of the target mask pattern 101.

[0084] In an exemplary embodiment of this disclosure, before forming the first photoresist layer 4, the method for forming the mask structure of this disclosure may further include:

[0085] Step S160: A second mask layer 5 is formed on the surface of the light-shielding layer 3, and the first photoresist layer 4 is located on the surface of the second mask layer 5.

[0086] like Figure 13 As shown, the material of the second mask layer 5 can be a material with a relatively high etch selectivity compared to the light-shielding layer 3. In some embodiments of this disclosure, the second mask layer 5 is made of the same material as the first mask layer 2. For example, both the second mask layer 5 and the first mask layer 2 are made of chromium, and the light-shielding layer 3 is made of molybdenum silicide. The thickness of the second mask layer 5 is relatively small. For example, its thickness can be 2nm to 20nm. For example, the thickness of the second mask layer 5 can be 2nm, 5nm, 10nm, 15nm, or 20nm. Of course, the second mask layer 5 can also have other thicknesses, which will not be listed here.

[0087] The second mask layer 5 can be formed on the surface of the light-shielding layer 3 by means of chemical vapor deposition, physical vapor deposition or atomic layer deposition. Of course, the second mask layer 5 can also be formed by other means. No special limitation is made on the formation method of the second mask layer 5 here.

[0088] In this embodiment, etching the light-shielding layer 3 in the first developing area 401 to form a first mask pattern 301 exposing the first mask layer 2 (i.e., step S130) includes steps S210 and S220, wherein:

[0089] In step S210, the second mask layer 5 is etched in the first developing area 401 to form an opening 501 that exposes the light-shielding layer 3.

[0090] like Figure 14 and Figure 15 As shown, the second mask layer 5 can be etched using a dry etching process to form an opening 501 within the second mask layer 5. The opening 501 can be a through-hole penetrating the second mask layer 5. The number of openings 501 is equal to the number of first developing areas 401. For example, when there is one first developing area 401, there is also one opening 501; when there are multiple first developing areas 401, there are also multiple openings 501. An opening 501 can be formed correspondingly below each first developing area 401.

[0091] It should be noted that after the opening 501 is formed, the first photoresist layer 4 can be removed by ashing or other processes, thereby exposing the surface of the remaining second mask layer 5.

[0092] In step S220, the light-shielding layer 3 is etched at the opening 501 to form a first mask pattern 301 that exposes the first mask layer 2. The etching selectivity ratio of the second mask layer 5 to the patterned film layer 1 is greater than the etching selectivity ratio of the light-shielding layer 3 to the patterned film layer 1.

[0093] Please continue reading Figure 7 and Figure 8 As shown, a second mask layer 5 with an opening 501 can be used as a mask to etch the light-shielding layer 3 exposed in the opening 501 using a dry etching process, thereby forming a first mask pattern 301 within the light-shielding layer 3. During this process, since the etch selectivity ratio between the second mask layer 5 and the light-shielding layer 3 is relatively large, the etch micro-load effect during the etching process of the light-shielding layer 3 can be effectively reduced by the second mask layer 5, improving the etch aspect ratio of the light-shielding layer 3 and helping to improve the resolution of the first mask pattern 301 formed within the light-shielding layer 3. At the same time, the presence of the second mask layer 5 can further reduce the thickness of the photoresist layer; its relatively small thickness helps to mitigate development collapse and further improve the resolution of the first mask pattern 301.

[0094] In some embodiments of this disclosure, when the material of the second mask layer 5 is the same as that of the first mask layer 2, when etching the first mask layer 2 exposed in the first mask pattern 301 to form a plurality of spaced second mask patterns 201 (i.e., performing step S140), at least a portion of the second mask layer 5 can be consumed simultaneously, thereby reducing the thickness of the second mask layer 5.

[0095] In an exemplary embodiment of this disclosure, before etching the patterned film layer 1 using the second mask pattern 201 as a mask (i.e., step S150), the method for forming the mask structure of this disclosure may further include steps S310-S330, wherein:

[0096] In step S310, a second photoresist layer 6 is formed on the side of the second mask layer 5 away from the patterned film layer 1. The orthographic projection of the second photoresist layer 6 on the patterned film layer 1 is located in the edge region B and coincides with the boundary of the edge region B.

[0097] In this embodiment, please continue to refer to Figure 9 As shown, there can be multiple second mask patterns 201, which can be spaced out, and the orthographic projections of the multiple second mask patterns 201 onto the patterned film layer 1 are all located in the central region A. Figure 16 As shown, a second photoresist layer 61 can be formed on the surface of the second mask layer 5 by spin coating or other methods. During this process, the second photoresist layer 61 can fill each opening 501, each first mask pattern 301, and each second mask pattern 201. The material of the second photoresist layer 61 can be photoresist. The second photoresist layer 61 can be exposed and developed to form a second developed area 611. The orthographic projection of the second developed area 611 on the film layer 1 to be patterned is located in the central region A, and its boundary coincides with the boundary of the central region A. That is, the second developed area 611 exposes each second mask pattern 201, and the orthographic projection of the remaining second photoresist layer 61 on the film layer 1 to be patterned is located in the edge region B, and coincides with the boundary of the edge region B. The remaining second photoresist layer 61 can be used as the second photoresist layer 6.

[0098] Step S320: Remove the second mask layer 5 and the light-shielding layer 3 from the areas not covered by the second photoresist layer 6.

[0099] like Figure 18 As shown, the second mask layer 5 and the light-shielding layer 3 exposed in the area not covered by the second photoresist layer 6 can be removed by a dry etching process, thereby exposing the surface of the first mask layer 2 corresponding to the central region A. It should be noted that the exposed first mask layer 2 contains all the second mask patterns 201.

[0100] Step S330: Remove the second photoresist layer 6.

[0101] The second photoresist layer 6 can be removed by ashing or other methods. Of course, other methods can also be used to remove the second photoresist layer 6; no specific limitation is made here regarding the method of removal. In this embodiment, the structure after step S330 is as follows: Figure 18 As shown.

[0102] In another exemplary embodiment of this disclosure, please continue to refer to Figure 8 As shown, there is one first mask pattern 301. The orthographic projection of the first mask pattern 301 onto the patterned film layer 1 is located in the central region A and coincides with the boundary of the central region A. Etching the first mask layer 2 exposed within the first mask pattern 301 to form multiple spaced second mask patterns 201 (i.e., step S140) includes steps S410-S430, wherein:

[0103] In step S410, a third photoresist layer 7 is formed on the surface of the second mask layer 5 away from the patterned film layer 1, and the third photoresist layer 7 fills the first mask pattern 301.

[0104] like Figure 19 As shown, a third photoresist layer 7 can be formed on the surface of the second mask layer 5 by spin coating or other methods. In this process, the third photoresist layer 7 can fill the opening 501 and the first mask pattern 301 opposite to the opening 501. The material of the third photoresist layer 7 can be photoresist.

[0105] In step S420, a plurality of spaced third developing regions 71 are formed in the third photoresist layer 7, and the orthographic projection of the third developing regions 71 on the patterned film layer 1 is located in the central region A.

[0106] like Figure 20 As shown, the third photoresist layer 7 can be exposed and developed to form multiple spaced third developing areas 71. Each third developing area 71 exposes the first mask layer 2 below it, and its orthographic projection on the film layer 1 to be patterned is located in the central region A. In the direction parallel to the film layer 1 to be patterned, the cross-section of the third developing area 71 can be circular, elliptical, rectangular, polygonal, or irregular in shape. No special limitation is made on the shape of the third developing area 71 here.

[0107] In step S430, the first mask layer 2 is etched in the third developing area 71 to form the second mask pattern 201.

[0108] The first mask layer 2 can be etched in the third developing area 71 by a dry etching process, thereby forming a plurality of second mask patterns 201 in the first mask layer 2. Each second mask pattern 201 can expose the patterned film layer 1 below it.

[0109] In one exemplary embodiment of this disclosure, the method for forming the mask structure may further include:

[0110] Step S440: Remove the third photoresist layer 7.

[0111] The third photoresist layer 7 can be removed by ashing or other methods. Of course, the third photoresist layer 7 can also be removed by other methods. No special limitation is made on the removal method of the third photoresist layer 7 here.

[0112] In one exemplary embodiment of this disclosure, after forming the target mask pattern 101, the method for forming the mask structure of this disclosure may further include:

[0113] Step S170: Remove the second mask layer 5 located in the edge region B and the remaining first mask layer 2 on the surface of the central region A.

[0114] The remaining second mask layer 5 and the remaining first mask layer 2 on the surface of the central region A can be removed by dry etching or other methods. Of course, other methods can also be used to remove the second mask layer 5 and the remaining first mask layer 2 on the surface of the central region A. No specific limitations are made here regarding the removal method of the second mask layer 5 and the remaining first mask layer 2 on the surface of the central region A. The etching gas used in the dry etching process can be set according to the specific materials of the second mask layer 5, the first mask layer 2, the light-shielding layer 3, and the film layer 1 to be patterned, as long as it can remove the second mask layer 5 and the remaining first mask layer 2 on the surface of the central region A without damaging the film layer 1 to be patterned and the remaining light-shielding layer 3 in the edge region B. In this embodiment, the structure after step S170 is as follows: Figure 21 As shown.

[0115] It should be noted that although the steps of the mask structure formation method in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that these steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or one step may be broken down into multiple steps.

[0116] This disclosure also provides a mask structure, which is formed by the mask structure forming method of any of the above embodiments. The specific details and manufacturing processes of each part of the above mask structure have been described in detail in the corresponding mask structure forming methods, and therefore will not be repeated here.

[0117] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A method for forming a mask structure, characterized in that, include: The patterned film layer, the first mask layer, the light-shielding layer, and the first photoresist layer are formed in sequence and stacked. A first development area is formed within the first photoresist layer; A second mask layer is formed on the surface of the light-shielding layer, and the first photoresist layer is located on the surface of the second mask layer; Etching the light-shielding layer in the first developing area to form a first mask pattern exposing the first mask layer includes: The second mask layer is etched in the first developing area to form an opening that exposes the light-shielding layer; The light-shielding layer is etched at the opening to form a first mask pattern that exposes the first mask layer. The etching selectivity ratio of the second mask layer to the patterned film layer is greater than that of the light-shielding layer to the patterned film layer. The first mask layer exposed within the first mask pattern is etched to form a plurality of spaced second mask patterns; The second mask pattern is used as a mask to etch the film layer to be patterned to form a target mask pattern. The etching selectivity ratio between the first mask layer and the film layer to be patterned is greater than the etching selectivity ratio between the light-shielding layer and the film layer to be patterned.

2. The forming method according to claim 1, characterized in that, The film layer to be patterned includes a central region and an edge region surrounding the outer periphery of the central region. The orthographic projection of the second mask pattern onto the film layer to be patterned is located in the central region. Before etching the film layer to be patterned using the second mask pattern as a mask, the formation method further includes: A second photoresist layer is formed on the side of the second mask layer away from the film layer to be patterned. The orthographic projection of the second photoresist layer on the film layer to be patterned is located in the edge region and coincides with the boundary of the edge region. Remove the second mask layer and the light-shielding layer from the areas not covered by the second photoresist layer; Remove the second photoresist layer.

3. The forming method according to claim 1, characterized in that, The patterned film layer includes a central region and an edge region surrounding the outer periphery of the central region. The orthographic projection of the first mask pattern onto the patterned film layer is located in the central region and coincides with the boundary of the central region. Etching is performed on the first mask layer exposed within the first mask pattern to form a plurality of spaced-apart second mask patterns, including: A third photoresist layer is formed on the surface of the second mask layer away from the patterned film layer, and the third photoresist layer fills the first mask pattern. Multiple spaced third developing regions are formed within the third photoresist layer, and the orthographic projection of the third developing region on the film layer to be patterned is located in the central region. The first mask layer is etched in the third developing area to form the second mask pattern.

4. The forming method according to claim 3, characterized in that, The forming method further includes: Remove the third photoresist layer.

5. The forming method according to claim 2 or 4, characterized in that, After forming the target mask pattern, the forming method further includes: Remove the second mask layer located in the edge region and the remaining first mask layer on the surface of the central region.

6. The forming method according to claim 1, characterized in that, The thickness of the first mask layer is 2nm to 20nm, and the thickness of the photoresist layer is 50nm to 100nm.

7. The forming method according to claim 1, characterized in that, The first mask layer and the second mask layer are made of the same material.

8. The forming method according to claim 1, characterized in that, The material of the film layer to be patterned is a transparent material.

9. A mask structure, characterized in that, The mask structure is formed by the method for forming a mask structure according to any one of claims 1-8.

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