Photomask and manufacturing method thereof

Abstract

The invention provides a photomask and a manufacturing method thereof. The manufacturing method comprises the following steps: providing an initial photomask; based on the structure information of the to-be-processed semiconductor structure and a first database, determining graph parameters of the target graph; and forming a target pattern in the target area of the initial photomask based on the pattern parameters to obtain a target photomask. In the disclosure, the target pattern is determined based on the structure information of the to-be-processed semiconductor structure and the first database, the target pattern is formed in the target area of the initial photomask to obtain the target photomask, and the target pattern can change the light transmittance of the target area so as to change the exposure speed and further control the exposure removal depth of the photoresist. When a plurality of target patterns are arranged in the target area, the photoresist with different depths can be formed in the photoresist layer through one-time exposure, so that the to-be-processed semiconductor structure with a three-dimensional structure is formed, the exposure times are reduced, the production efficiency is improved, and the number of photomasks is reduced, so that the cost is reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a photomask and a method for manufacturing the same. Background Art

[0002] Semiconductor structures are developing towards three-dimensional (3D) structures, which have higher integration density and can provide stronger performance. However, semiconductor structures with three-dimensional structures have more complicated manufacturing steps.

[0003] At present, semiconductor structures are usually made by photolithography technology. When a mask in the related technology is used to expose the photoresist on the semiconductor structure, the manufacturing process is cumbersome and inefficient. In addition, each process requires a corresponding mask, which makes the number of masks huge and increases the cost. Summary of the invention

[0004] The following is a summary of the subject matter of the detailed description of the present disclosure. This summary is not intended to limit the scope of the claims.

[0005] In a first aspect of the present disclosure, a method for manufacturing a photomask is provided, comprising:

[0006] Provide initial photomask;

[0007] Determining graphic parameters of a target graphic based on structural information of the semiconductor structure to be processed and a first database, wherein the target graphic is used to adjust the transmittance of a target area of ​​the initial mask, and the first database is used to characterize the corresponding relationship between the structural information and the graphic parameters, and the graphic parameters include the density of a plurality of sub-graphics contained in the target graphic;

[0008] Based on the pattern parameters, the target pattern is formed in the target area of ​​the initial mask to obtain a target mask.

[0009] In some embodiments, the first database includes a first sub-database and a second sub-database, and determining the graphic parameters of the target graphic based on the structural information of the semiconductor structure to be processed and the first database includes:

[0010] Based on the structural information, determining a target thickness of the photoresist layer corresponding to the target area on the semiconductor structure to be processed, wherein the target thickness is the thickness of the photoresist layer after being exposed;

[0011] Determining a target transmittance of the target area based on the target thickness and the first sub-database, wherein the first sub-database is used to characterize a corresponding relationship between the transmittance and the thickness of the photoresist layer;

[0012] Based on the target light transmittance and the second sub-database, the density of the plurality of sub-patterns in the target pattern is determined, and the second sub-database is used to characterize the corresponding relationship between the light transmittance and the density of the sub-patterns.

[0013] In some embodiments, determining a target thickness of a photoresist layer corresponding to the target area on the semiconductor structure to be processed based on the structural information includes:

[0014] Based on the structural information, determining a first preset thickness of the photoresist layer corresponding to the target area, the first preset thickness being the thickness of the portion of the photoresist layer that needs to be removed, and the structural information including a second preset thickness of an area of ​​the semiconductor structure to be processed corresponding to the target area;

[0015] The target thickness is determined based on the first preset thickness, the second preset thickness, and an initial thickness of the photoresist layer.

[0016] In some embodiments, the graphic parameters further include shapes and sizes of the plurality of sub-graphics contained in the target graphic.

[0017] In some embodiments, the target area includes a first area and a second area, and the target graphic includes a first target graphic and a second target graphic;

[0018] The forming of the target pattern in the target area of ​​the initial mask comprises:

[0019] Opening a hole in the first area to form a first target pattern, so that part of the exposure light can pass through the first area; and / or,

[0020] A light shielding structure is filled in the second region to form a second target pattern to reduce the light transmittance of the second region.

[0021] In some embodiments, filling the second region with a light shielding structure to form the target pattern includes:

[0022] forming a plurality of through holes in the second region, wherein the through holes penetrate the initial mask along a thickness direction of the initial mask, and the number of the through holes is the same as the number of sub-patterns in the second target pattern;

[0023] A light shielding structure made of a light shielding material is filled in the plurality of through holes, and the plurality of light shielding structures form the second target pattern.

[0024] In some embodiments, after determining the target pattern, the method for making the mask further includes:

[0025] Based on preset rules, performing quality inspection on the plurality of sub-graphs in the target graph;

[0026] If the plurality of sub-patterns all meet the preset rule, the target pattern is formed on the initial mask.

[0027] In a second aspect of the present disclosure, a photomask is provided, comprising:

[0028] a substrate, including a target area;

[0029] A target pattern, arranged in a target area of ​​the substrate, the target pattern being composed of a plurality of sub-patterns;

[0030] The target pattern enables the target area to have a target light transmittance, so that the photoresist layer corresponding to the target area has a target thickness after being exposed.

[0031] In some embodiments, the target area includes a first area and a second area, and the target graphic includes a first target graphic and a second target graphic;

[0032] Wherein, the first region is provided with the first target pattern formed by opening along the thickness direction of the substrate, and other structures of the first region except the first target pattern are made of light-shielding material; and / or,

[0033] The second area is provided with a plurality of light-shielding structures, the plurality of light-shielding structures constitute the second target pattern, and other structures in the second area except the second target pattern are made of a light-transmitting material.

[0034] In some embodiments, the shape of the sub-graphic includes a rectangle, a triangle, a circle or a special shape; and / or,

[0035] In the length and width directions of the mask, the size of the sub-pattern is less than or equal to 100 nm.

[0036] In the method for making a mask provided by the present invention, a target pattern is determined based on the structural information of the semiconductor structure to be processed and a first database, and the target pattern is formed in a target area of ​​an initial mask to obtain a target mask. The target pattern can change the transmittance of the target area, thereby changing the exposure speed, and further controlling the depth of the photoresist removed by exposure. When a plurality of target patterns are provided in the target area, photoresists of different depths can be formed in the photoresist layer through a single exposure, thereby forming a three-dimensional structure of the semiconductor structure to be processed, thereby reducing the number of exposures, improving production efficiency, and reducing the number of masks to reduce costs.

[0037] Other aspects will be apparent upon reading and understanding the drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings incorporated into the specification and constituting a part of the specification illustrate embodiments of the present disclosure and are used together with the description to explain the principles of the embodiments of the present disclosure. In these drawings, similar reference numerals are used to represent similar elements. The drawings described below are some embodiments of the present disclosure, rather than all embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 The present invention is a flow chart of a method for manufacturing a photomask according to an exemplary embodiment.

[0040] Figure 2 is a flow chart of a method for manufacturing a photomask according to another exemplary embodiment.

[0041] Figure 3 is a flow chart of a method for manufacturing a photomask according to yet another exemplary embodiment.

[0042] Figure 4 It is a schematic diagram of forming a photoresist layer with a pattern on a substrate in the related art.

[0043] Figure 5 FIG. 4 is a schematic diagram showing a method of forming a photoresist layer having a pattern according to an exemplary embodiment of the present disclosure.

[0044] Figure 6 FIG. 4 is a schematic diagram showing a method of forming a photoresist layer having a pattern according to another exemplary embodiment of the present disclosure.

[0045] Figure 7 FIG. 4 is a schematic diagram showing a method of forming a photoresist layer having a pattern according to another exemplary embodiment of the present disclosure.

[0046] Figure 8 FIG. 4 is a schematic diagram showing a photoresist layer after patterning according to an exemplary embodiment.

[0047] Fig. 9 FIG. 4 is a schematic diagram showing a method of forming a semiconductor structure to be processed according to an exemplary embodiment.

[0048] Fig.10 FIG. 4 is a schematic diagram showing a method of forming a semiconductor structure to be processed according to an exemplary embodiment.

[0049] Fig.11 is a schematic diagram showing a semiconductor structure to be processed according to an exemplary embodiment.

[0050] Reference numerals:

[0051] 10', initial photomask; 11', light shielding area; 12', light transmitting area; 20', photoresist layer; 30', substrate;

[0052] 10. Target mask;

[0053] 11. target area; 111. first area; 112. second area;

[0054] 12, target graphic; 12a, sub-graphic; 121, first target graphic; 122, second target graphic;

[0055] 20. photoresist layer; 21. first groove; 22. second groove;

[0056] 30. substrate;

[0057] 40. Semiconductor structure; 41. First structure; 42. Second structure. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the disclosed embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present disclosure. It should be noted that the embodiments in the present disclosure and the features in the embodiments can be arbitrarily combined with each other without conflict.

[0059] See also Figure 4 , showing that in the related art, photolithography technology is used to manufacture a semiconductor structure. When an initial mask 10' is used to expose a photoresist layer 20' of a substrate 30', each exposure can only remove the photoresist layer 20' of the same thickness, and then a semiconductor structure is formed in the area where the photoresist is removed. That is, after each exposure, only a semiconductor circuit in a planar form can be formed, resulting in a cumbersome manufacturing process and a large number of masks, which increases the manufacturing cost.

[0060] In order to solve the above problems, the embodiment of the present disclosure provides a photomask and a method for making the same, the method comprising the following steps: providing an initial photomask; determining the graphic parameters of the target graphic based on the structural information of the semiconductor structure to be processed and a first database; forming the target graphic in the target area of ​​the initial photomask based on the graphic parameters to obtain the target photomask. In the present disclosure, the target graphic can change the transmittance of the target area, thereby changing the exposure speed, and then controlling the depth of the photoresist removed by exposure. When the target area is provided with multiple target graphics, photoresists of different depths can be formed in the photoresist layer through a single exposure, thereby forming a semiconductor structure to be processed with a three-dimensional structure, reducing the number of exposures, improving production efficiency, and reducing the number of masks to reduce costs.

[0061] In an exemplary embodiment of the present disclosure, a method for manufacturing a photomask is provided, such as Figure 1 As shown, the method for making a photomask may include the following steps:

[0062] Step S110: providing an initial mask.

[0063] In this step, refer to Figure 4 The initial photomask 10' can be a photomask with a circuit pattern already formed in the related art. For example, the chip foundry can provide the currently used photomask to the photomask manufacturing plant, and the photomask manufacturing plant can design the existing initial photomask 10' using the photomask manufacturing method provided by the embodiment of the present disclosure. In this step, the production is performed on the basis of the initial photomask 10' with a circuit pattern already formed, which can greatly shorten the production time.

[0064] In some optional embodiments, the initial photomask 10' may also be a substrate without a circuit pattern formed thereon, that is, the photomask manufacturing plant needs to manufacture the target photomask 10 from scratch. When processing the substrate without a circuit pattern formed thereon, compared with the aforementioned example, the original pattern (i.e., the circuit pattern) and the newly added pattern (i.e., the target pattern 12) are manufactured by the same process, and there is no need to align the newly added pattern with the original pattern, which is conducive to improving the yield of the manufactured target photomask 10.

[0065] Step S120: determining graphic parameters of the target graphic based on the structural information of the semiconductor structure to be processed and the first database.

[0066] In this step, refer to Figures 5 to 7 The semiconductor structure 40 to be processed is the semiconductor structure 40 that needs to be produced using the target mask 10. The semiconductor structure 40 is formed on a substrate 30, such as a wafer. The semiconductor structure 40 can form a processor chip, a memory, etc.

[0067] Among them, the semiconductor structure 40 needs to go through multiple processes such as photolithography, deposition and grinding before it is fully formed, so that the semiconductor structure 40 to be processed presents a variety of different shapes during the forming process, and each shape has corresponding structural information. For example, each time the shape structure of the semiconductor structure 40 to be processed changes due to photolithography, deposition or grinding, a corresponding structural information after the process step is completed will be generated. The number of target masks 10 corresponds to the number of structural information. In one example, the number of target masks 10 can be calculated along the height direction of the semiconductor structure 40 ( Figure 7 The semiconductor structures 40 are grouped into a plurality of stages, each of which has a corresponding target mask 10 .

[0068] Among them, see Figure 7The structural information of the semiconductor structure 40 to be processed can represent the shape, size, etc. of the semiconductor structure 40 to be processed. For example, the structural information may include the projection of the semiconductor structure 40 to be processed on the substrate (e.g. Figure 7 The shape of the target graphic 12 (such as L-shaped as shown) and the thickness of each part of the projection can be determined by the projection graphic. Figure 7 The density of the sub-patterns 12a corresponding to different positions of the target pattern 12 can be determined by the thickness of each portion.

[0069] Among them, Figure 5 and Figure 6 As shown, the target pattern 12 is formed in the target area 11 of the initial mask 10' to change (increase or decrease) the transmittance of the target area 11 of the initial mask 10'. The transmittance is the ratio of the remaining intensity of the exposure light after passing through the mask to the original intensity. The higher the transmittance, the stronger the exposure light and the higher the efficiency of the photoresist being exposed. Exemplarily, when the photoresist is a positive photoresist, compared with the photoresist corresponding to the 90% transmittance area, the photoresist in the 45% transmittance area will have less structure removed after being exposed for the same time, thereby having a greater thickness.

[0070] The first database is used to characterize the correspondence between the structural information and the graphic parameters of the target graphic 12. Exemplarily, the graphic parameters include the density of the multiple sub-graphics 12a constituting the target graphic 12, and the structural information includes the thickness and shape of the semiconductor structure 40 to be processed.

[0071] For example, see Figures 7 to 11 The semiconductor structure 40 to be processed includes a first structure 41 and a second structure 42. The first structure 41 and the second structure 42 are arranged in an "L" shape. The first structure 41 is arranged along a first direction ( Fig.10 The second structure 42 extends in the second direction (x direction) and has a thickness m. Fig.10 y direction as shown in the figure and having a thickness of n, m is greater than n, it can be determined that the target area 11 is also in an "L" shape, the area of ​​the target area 11 corresponding to the first structure 41 is provided with a sub-graphic 12a of a first preset density, and the area of ​​the target area 11 corresponding to the second structure 42 is provided with a sub-graphic 12a of a second preset density, the first preset density is greater than the second preset density, and the sub-graphics 12a of different preset densities make different positions of the target area 11 have different densities, so that a single exposure and development process can remove photoresists of different depths in different areas. For example, refer to Figure 7 and Figure 8 , in the thickness direction of the target mask 10 ( Fig.10In the z direction shown in FIG. 1 , the thickness of the photoresist layer 20 corresponding to the first structure 41 is removed to form a first groove 21 with a depth of m, and the thickness of the photoresist layer 20 corresponding to the second structure 42 is removed to form a second groove 22 with a thickness of n. The top surface of the second groove 22 is higher than the top surface of the first groove 21. Next, referring to FIG. Fig. 9 A deposition process may be used to form a three-dimensional semiconductor structure 40 in the first groove 21 and the second groove 22 .

[0072] Here, it should be noted that the sub-pattern 12a provided in the embodiment of the present disclosure is a fine pattern. In the length and width directions of the mask, the size of the sub-pattern 12a does not exceed 100nm. After the exposure light passes through the sub-pattern 12a, it can be diffracted and scattered to illuminate the entire target area 11, and the target pattern 12 will not be transferred to the photoresist layer 20, that is, the top surface of the photoresist layer 20 facing the target area 11 will be removed relatively smoothly. As can be seen from the above, the manufacturing method provided in this embodiment can make the target area 11 of the mask have different transmittances, so that the photoresist layer 20 of different thicknesses can be removed in one exposure operation, and then a three-dimensional, solid semiconductor structure 40 is directly formed in the area where the photoresist is removed.

[0073] Step S130 : forming a target pattern in a target area of ​​the initial mask based on the pattern parameters to obtain a target mask.

[0074] In this step, for example, an electron beam mask lithography device may be used to transfer the target pattern 12 to the target region 11 of the initial mask 10 ′, thereby obtaining the target mask 10 .

[0075] In this embodiment, the target pattern can change the transmittance of the target area, thereby changing the exposure speed, and further controlling the depth of the photoresist removed by exposure. When the target area is provided with multiple target patterns, photoresists of different depths can be formed in the photoresist layer through a single exposure, thereby forming a three-dimensional structure of the semiconductor structure to be processed, reducing the number of exposures, improving production efficiency, and reducing the number of masks to reduce costs.

[0076] In some embodiments, this embodiment is a further description of step S120 in the above embodiment. Step S120, forming a target pattern in the target area of ​​the initial mask, may specifically include the following steps:

[0077] Step S121, forming a first target pattern by opening a hole in the first area, so that part of the exposure light can pass through the first area.

[0078] Among them, Figure 5As shown, the target area 11 includes a first area 111 and a second area 112. The first area 111 may be a light shielding area 11' in the initial mask 10'. The first area 111 of the initial mask 10' can completely block the exposure light, so that the photoresist layer 20 directly facing the first area 111 has the same and higher height. In this embodiment, a plurality of through holes (i.e., sub-patterns 12a) may be opened in the first area 111 (light shielding area 11') of a portion of the initial mask 10', thereby forming a first target pattern 121, so that a portion of the exposure light can pass through the first area 111 through the through holes and irradiate the photoresist layer 20, and the irradiated area of ​​the photoresist layer 20 may be removed. For example, see Figure 5 As the density of the sub-pattern 12a in the first target pattern 121 gradually increases, the thickness of the photoresist layer 20 corresponding to the first area 111 after being exposed and developed gradually decreases. That is, by setting the sub-pattern, different positions of the photoresist layer 20 that originally has the same height and is relatively high can present different heights, thereby defining semiconductor structures 40 with different thicknesses at different positions.

[0079] Step S122: Fill the second region with a light shielding structure to form a second target pattern to reduce the light transmittance of the second region.

[0080] The second region 112 may be the light-transmitting region 12 ′ in the initial mask 10 ′.

[0081] In one example, the second target pattern 122 can be formed in the following manner: a plurality of through holes are formed in the second region 112, the through holes penetrate the initial mask 10' along the thickness direction of the initial mask 10', and the number of the through holes is the same as the number of sub-patterns 12a in the second target pattern 122. A light shielding structure made of a light shielding material is filled in the plurality of through holes, and the plurality of light shielding structures constitute the second target pattern 122. The light shielding material is, for example, metal silicide.

[0082] In another example, the second target pattern 122 can be formed in the following manner: a plurality of light shielding films are formed in the second region 112 using existing processes such as sputtering and distillation, each light shielding film has the same shape and size as the sub-pattern 12a, and the plurality of light shielding films constitute the second target pattern 122. The light shielding films can be made of metal silicide.

[0083] In an exemplary embodiment, Figure 2 As shown, the embodiment of the present disclosure provides a method for manufacturing a photomask, comprising the following steps:

[0084] Step S210: providing an initial mask.

[0085] The implementation method and principle of this step are the same as those of step S110 and will not be repeated here.

[0086] Step S220: determining a target thickness of the photoresist layer corresponding to the target area on the semiconductor structure to be processed based on the structural information.

[0087] The photomask produced by the production method provided in the embodiment of the present disclosure is applied to the photolithography process, and the photolithography process includes processes such as spin coating, exposure, development, deposition and etching. Spin coating can form a photoresist on a wafer, and then the photoresist is exposed, and the photoresist irradiated by the exposure light (such as ultraviolet light) reacts, and then the photoresist (taking positive photoresist as an example) irradiated by the exposure light can be removed using a developer, and the photoresist that is not irradiated will be retained, and then, semiconductor material can be deposited in the area where the photoresist is removed to form a semiconductor structure 40.

[0088] It can be seen from the above that the shape of the removed photoresist layer 20 is related to the shape of the semiconductor structure 40, so that the target thickness of the photoresist layer 20 corresponding to the target area 11 can be determined according to the structural information of the semiconductor structure 40 to be manufactured, and then the semiconductor structure 40 of the specified shape can be manufactured.

[0089] In some embodiments, step S220 may specifically include the following steps:

[0090] Step S221: determining a first preset thickness of a photoresist layer corresponding to a target area based on structural information, wherein the structural information includes a second preset thickness of an area of ​​the semiconductor structure to be processed corresponding to the target area.

[0091] In this step, the first preset thickness is the thickness of the portion of the photoresist layer 20 that needs to be removed.

[0092] Step S222: determining a target thickness based on the first preset thickness, the second preset thickness, and the initial thickness of the photoresist layer.

[0093] In this step, the first preset thickness can be determined based on the second preset thickness, and then the target thickness can be determined based on the initial thickness and the first preset thickness of the photoresist layer 20. The target thickness of the photoresist layer 20 is the thickness remaining after exposure and development.

[0094] Exemplarily, the thickness of the semiconductor structure 40 to be formed (i.e., the second preset thickness) is a, and the area on the wafer corresponding to the target area 11 has a photoresist layer 20 with a thickness (i.e., the initial thickness) of b, b≥a, and the photoresist layer 20 corresponding to the target area 11 needs to be removed of the first preset thickness of photoresist c, c≤b. If the subsequently formed semiconductor structure 40 can just fill the area from which the photoresist is removed, then a=c, i.e., the first preset thickness is equal to the second preset thickness, so that the target thickness of the photoresist layer 20 is bc, i.e., the target thickness is the difference between the initial thickness and the first preset thickness.

[0095] Step S230: Determine the target light transmittance of the target area based on the target thickness and the first sub-database.

[0096] In this step, the first database includes a first sub-database, and the first sub-database is used to characterize the corresponding relationship between the thickness and transmittance of the photoresist layer 20. That is, as long as the target thickness is determined, the target transmittance that can achieve the target thickness can be found in the first sub-database.

[0097] Step S240: Determine the density of the plurality of sub-patterns in the target pattern based on the target light transmittance and the second sub-database.

[0098] In this step, the first database includes a second sub-database, and the second sub-database is used to characterize the corresponding relationship between the transmittance and the density of the sub-graphic 12a. That is, after determining the target transmittance, the density of the sub-graphic 12a that makes the target area 11 have the target transmittance can be found in the second sub-database, and the density of the sub-graphic 12a is used as the graphic parameter of the target graphic 12.

[0099] Step S250: forming a target pattern in a target area of ​​the initial mask based on the pattern parameters to obtain a target mask.

[0100] The implementation method and principle of this step are the same as those of step S130 in the aforementioned embodiment, and will not be repeated herein.

[0101] In this embodiment, when the structural information is determined, the density of the sub-graphic 12 a can be determined quickly and accurately by using the first sub-database and the second sub-database, that is, the graphic parameters of the target graphic 12 can be determined.

[0102] In some embodiments, this embodiment is a further description of step S120 in the above embodiment, see Figure 5 and Figure 6 , based on the structural information of the semiconductor structure 40 to be processed and the first database, the graphic parameters of the target graphic 12 are determined, and the graphic parameters may also include the shapes and sizes of the multiple sub-graphics 12a in the target graphic 12. It can be understood that, when the size and shape of the sub-graphics 12a are controlled to remain unchanged, the greater the density of the sub-graphics 12a, the larger the area of ​​the target graphic 12, and the greater the change in the transmittance of the target area 11 of the initial mask 10'. Therefore, the transmittance of the target area 11 can also be adjusted by adjusting the shape and size of the sub-graphics 12a.

[0103] In one example, the sub-pattern 12a may be in a rectangular, circular, triangular, hexagonal or irregular shape. In the length and width directions of the mask, the size of the sub-pattern 12a does not exceed 100 nm.

[0104] In an exemplary embodiment, Figure 3 As shown, this embodiment provides a method for manufacturing a photomask, comprising the following steps:

[0105] Step S310: providing an initial mask.

[0106] The implementation method and principle of this step are the same as those of step S110 in the aforementioned embodiment, and will not be described in detail.

[0107] Step S320: determining graphic parameters of the target graphic based on the structural information of the semiconductor structure to be processed and the first database.

[0108] The implementation method and principle of this step are the same as those of step S120 in the aforementioned embodiment, and will not be repeated herein.

[0109] Step S330: Based on preset rules, quality inspection is performed on multiple sub-graphs in the target graph.

[0110] In this step, it can be understood that the sub-patterns 12a constituting the target pattern 12 are small-sized (not exceeding 100 nm) patterns and are in large numbers. The smaller the size, the lower the yield. Therefore, the sub-patterns 12a can be quality inspected to ensure the yield of the target mask 10 manufactured subsequently. The preset rules can be formulated by the mask manufacturer or by the consumer who needs the mask.

[0111] In an example, the preset rule may be whether the density of the sub-graphics 12 a reaches a preset threshold, and the distribution uniformity of the multiple sub-graphics 12 a in the target area 11 .

[0112] In another example, the preset rule may be the shape and size of the sub-pattern 12a. By checking the shape of the sub-pattern 12a, it is possible to avoid the sub-pattern 12a being too large, resulting in the sub-pattern 12a being transferred to the photoresist, and to avoid the sub-pattern 12a being too small and slit-shaped, thereby failing to effectively adjust the transmittance of the target area 11.

[0113] If the plurality of sub-patterns 12a all meet the preset rules, step S340 is executed. If not, the mask manufacturing factory can choose to send the target pattern 12 to the consumer who purchased the mask for confirmation. If the confirmation is passed, step S340 is executed. If not, step S320 is returned to be executed, that is, the target pattern 12 is re-determined.

[0114] Step S340: forming a target pattern in the target area of ​​the initial mask based on the pattern parameters to obtain a target mask.

[0115] The implementation method and principle of this step are the same as those of step S130 in the aforementioned embodiment, and will not be repeated herein.

[0116] Step S350: Perform quality inspection on the target pattern on the target mask.

[0117] In this step, the same preset rules as step S330 may be used for quality inspection, which will not be described in detail.

[0118] If the quality inspection passes, step S360 is executed. If not, the target photomask 10 is scrapped.

[0119] Step S360: Use the target mask to perform exposure and confirm the photoresist pattern after exposure and development.

[0120] This step simulates the actual production to expose and develop the photoresist. If the formed photoresist pattern meets the requirements, it means that the target mask 10 is qualified.

[0121] According to an exemplary embodiment of the present disclosure, Figures 5 to 7 As shown, an embodiment of the present disclosure provides a photomask, which may be the target photomask 10 provided by any of the foregoing embodiments of the present disclosure.

[0122] like Figures 5 to 7 As shown, the target photomask 10 includes a substrate, which serves as a carrier of the pattern (circuit pattern, target pattern 12) on the photomask. The substrate can be made of a transparent material or a light-shielding material. The transparent material is, for example, quartz or soda glass, and the light-shielding material is, for example, metal silicide.

[0123] See also Figures 5 to 7 , the target mask 10 also includes a circuit pattern, the circuit pattern is arranged on the substrate, and the circuit pattern can be transferred to the photoresist layer 20, thereby manufacturing a semiconductor structure 40. Exemplarily, Figure 5 A plurality of rectangular circuit patterns are shown. Figure 7 An L-shaped circuit pattern is shown.

[0124] See also Figures 5 to 7 The target mask 10 further includes a target pattern 12, which is composed of a plurality of sub-patterns 12a. The target pattern 12 is disposed in a target region 11 of the substrate, and the density of the plurality of sub-patterns 12a in the target pattern 12 can be adaptively set so that the transmittance of the target region 11 is a target transmittance, so that the photoresist layer 20 corresponding to the target region 11 has a target thickness after being exposed.

[0125] In the disclosed embodiments, the target pattern can change the transmittance of the target area, thereby changing the exposure speed, and further controlling the depth of the photoresist removed by exposure. When the target area is provided with multiple target patterns, photoresists of different depths can be formed in the photoresist layer through a single exposure, thereby forming a three-dimensional semiconductor structure to be processed, reducing the number of exposures, improving production efficiency, and reducing the number of masks to reduce costs.

[0126] Among them, see Figure 5 , the first region 111 is provided with a first target pattern 121, and the first target pattern 121 can be formed by a through hole penetrating the substrate. The other structures of the first region 111 except the first target pattern 121 are composed of a light-shielding material, and it can be determined that the first region 111 of the initial photomask 10' is a region with a light transmittance equal to 0. After exposure and development, the shape of the photoresist layer 20 corresponding to the first region 111 of the initial photomask 10' will not change. In the photomask provided in this embodiment, the first target pattern 121 is formed by a through hole or a light-transmitting material that allows light to pass through, so that part of the exposure light can pass through the first region 111 to expose the photoresist layer 20 directly below the first region 111, so that part of the structure of the photoresist layer 20 is removed.

[0127] Among them, see Figure 6 The second region 112 is provided with a second target pattern 122, the second target pattern 122 is composed of a plurality of light-shielding structures, and other structures of the second region 112 except the second target pattern 122 are made of a light-transmitting material.

[0128] The shape of the sub-graphic 12a of the target graphic 12 may be any one of a rectangle, a triangle, a circle, a regular hexagon or a special shape. Figure 5 A sub-pattern 12a having a rectangular shape is shown.

[0129] Among them, see Figure 5 , in the length of the mask ( Figure 7 in the x direction) and width ( Figure 7 In the y direction (shown in FIG. 2 ), the size of the sub-pattern 12a is less than or equal to 100 nm. By setting the size of the sub-pattern 12a to be less than or equal to 100 nm, the sub-pattern 12a can be prevented from being clearly transferred to the photoresist.

[0130] The various embodiments or implementation methods in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referenced to each other.

[0131] In the description of this specification, reference to the terms "embodiment", "exemplary embodiment", "some embodiments", "illustrative embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure.

[0132] In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0133] In the description of the present disclosure, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present disclosure.

[0134] It is to be understood that the terms "first", "second", etc. used in the present disclosure can be used to describe various structures in the present disclosure, but these structures are not limited by these terms. These terms are only used to distinguish a first structure from another structure.

[0135] In one or more of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the parts in the accompanying drawings are not drawn to scale. In addition, some well-known parts may not be shown. For the sake of simplicity, the structure obtained after several steps can be described in one figure. Many specific details of the present disclosure, such as the structure, materials, dimensions, processing technology and technology of the device are described below to more clearly understand the present disclosure. However, as those skilled in the art will appreciate, the present disclosure may not be implemented in accordance with these specific details.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A method for making a photomask, characterized in that: include: Provide initial photomask; Determining graphic parameters of a target graphic based on structural information of the semiconductor structure to be processed and a first database, wherein the target graphic is used to adjust the transmittance of a target area of ​​the initial mask, and the first database is used to characterize the corresponding relationship between the structural information and the graphic parameters, and the graphic parameters include the density of a plurality of sub-graphics contained in the target graphic; Based on the pattern parameters, the target pattern is formed in the target area of ​​the initial mask to obtain a target mask.

2. The method for manufacturing a photomask according to claim 1, characterized in that: The first database includes a first sub-database and a second sub-database, and determining the graphic parameters of the target graphic based on the structural information of the semiconductor structure to be processed and the first database includes: Based on the structural information, determining a target thickness of a photoresist layer corresponding to the target area on the semiconductor structure to be processed, wherein the target thickness is a thickness of the photoresist layer after being exposed; Determining a target transmittance of the target area based on the target thickness and the first sub-database, wherein the first sub-database is used to characterize a corresponding relationship between the transmittance and the thickness of the photoresist layer; Based on the target light transmittance and the second sub-database, the density of the plurality of sub-patterns in the target pattern is determined, and the second sub-database is used to characterize the corresponding relationship between the light transmittance and the density of the sub-patterns.

3. The method for manufacturing a photomask according to claim 2, characterized in that: The step of determining a target thickness of a photoresist layer corresponding to the target area on the semiconductor structure to be processed based on the structural information includes: Based on the structural information, determining a first preset thickness of the photoresist layer corresponding to the target area, the first preset thickness being the thickness of the portion of the photoresist layer that needs to be removed, and the structural information including a second preset thickness of an area of ​​the semiconductor structure to be processed corresponding to the target area; The target thickness is determined based on the first preset thickness, the second preset thickness, and an initial thickness of the photoresist layer.

4. The method for manufacturing a photomask according to claim 1, characterized in that: The graphic parameters also include shapes and sizes of the multiple sub-graphics contained in the target graphic.

5. The method for manufacturing a photomask according to any one of claims 1 to 4, characterized in that: The target area includes a first area and a second area, and the target graphic includes a first target graphic and a second target graphic; The forming of the target pattern in the target area of ​​the initial mask comprises: Opening a hole in the first area to form a first target pattern, so that part of the exposure light can pass through the first area; and / or, A light shielding structure is filled in the second region to form a second target pattern to reduce the light transmittance of the second region.

6. The method for manufacturing a photomask according to claim 5, characterized in that: Filling the second area with a light shielding structure to form the target pattern includes: forming a plurality of through holes in the second region, wherein the through holes penetrate the initial mask along a thickness direction of the initial mask, and the number of the through holes is the same as the number of sub-patterns in the second target pattern; A light shielding structure made of a light shielding material is filled in the plurality of through holes, and the plurality of light shielding structures form the second target pattern.

7. The method for manufacturing a photomask according to claim 1, characterized in that: After determining the target pattern, the method for making the mask further includes: Based on preset rules, performing quality inspection on the plurality of sub-graphs in the target graph; If the plurality of sub-patterns all meet the preset rule, the target pattern is formed on the initial mask.

8. A photomask, characterized in that: include: a substrate, including a target area; A target pattern, arranged in a target area of ​​the substrate, the target pattern being composed of a plurality of sub-patterns; The target pattern enables the target area to have a target light transmittance, so that the photoresist layer corresponding to the target area has a target thickness after being exposed.

9. The photomask according to claim 8, wherein: The target area includes a first area and a second area, and the target graphic includes a first target graphic and a second target graphic; Wherein, the first region is provided with the first target pattern formed by opening along the thickness direction of the substrate, and other structures of the first region except the first target pattern are made of light-shielding material; and / or, The second area is provided with a plurality of light-shielding structures, the plurality of light-shielding structures constitute the second target pattern, and other structures in the second area except the second target pattern are made of a light-transmitting material.

10. The photomask according to claim 8 or 9, characterized in that: The shape of the sub-graphics includes a rectangle, a triangle, a circle or a special shape; and / or, In the length and width directions of the mask, the size of the sub-pattern is less than or equal to 100 nm.

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