Mask and method for manufacturing same

Abstract

The invention provides a mask plate and a method for manufacturing the mask plate. The mask plate comprises a substrate, the substrate is provided with a first surface and a second surface which are opposite, the first surface is a surface with patterns, a plurality of process pixel points used for line width size correction are arranged in the substrate and are arranged in the first direction, the first direction is parallel to the first surface and the second surface, and the second direction is parallel to the second surface. The distance between the process pixel points and the second surface is larger than that between the process pixel points and the first surface; and the process film is formed on the first surface and / or the second surface of the substrate so as to ensure that the substrate recovers a horizontal state along the first direction. According to the embodiment of the invention, the line width uniformity of the wafer manufactured by using the mask plate can be improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of integrated circuit manufacturing, and in particular, to a mask and a method for manufacturing the mask. Background Art

[0002] Critical Dimension Correction (CDC) is a technology used in the photolithography process in the field of integrated circuits. It controls the critical dimensions in the chip manufacturing process, such as line width, spacing, shape, etc., by controlling the exposure time, light source intensity, mask design and other parameters of the photolithography machine. In the CDC technology, lasers can also be used to micro-process the lattice of the quartz mask to form process pixels that change its refractive index, so that part of the light is scattered outside the scanning lens pupil, reducing the intensity of the light, thereby changing the line width and achieving the effect of line width correction.

[0003] In the related art, the process pixel point can only be set at the center of the mask to avoid stress deformation of the mask due to asymmetric expansion, which makes the effect of CDC correction limited and difficult to perform large-scale line width size correction.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The purpose of the present disclosure is to provide a mask and a method for manufacturing the mask, so as to increase the degree of improvement of the line width uniformity of the mask.

[0006] According to a first aspect of the present disclosure, a mask is provided, comprising: a substrate having a first surface and a second surface relative to each other, the first surface being a surface having a pattern, a plurality of process pixel points for line width dimension correction being arranged inside the substrate, the plurality of process pixel points being arranged along a first direction, the first direction being parallel to both the first surface and the second surface, the distance between the plurality of process pixel points and the second surface being greater than the distance between the plurality of process pixel points and the first surface; and a process film formed on the first surface and / or the second surface of the substrate to ensure that the substrate is restored to a horizontal state along the first direction.

[0007] In an exemplary embodiment of the present disclosure, the process film is a shrinkage film formed on the first surface of the substrate to tighten the first surface, or the process film is a tension film formed on the second surface of the substrate to extend the second surface.

[0008] In an exemplary embodiment of the present disclosure, a process film includes a first process film and a second process film.

[0009] In an exemplary embodiment of the present disclosure, a first process film is formed on a first surface of a substrate, and a second process film is formed on a second surface of the substrate.

[0010] In an exemplary embodiment of the present disclosure, a first process film and a second process film are stacked and formed on a first surface of a substrate.

[0011] In an exemplary embodiment of the present disclosure, the first process film and the second process film are stacked and formed on the second surface of the substrate.

[0012] In an exemplary embodiment of the present disclosure, the first process film is a shrink film, and the second process film is a tension film.

[0013] In an exemplary embodiment of the present disclosure, both the first process film and the second process film are shrink films.

[0014] In an exemplary embodiment of the present disclosure, both the first process film and the second process film are tension films.

[0015] In an exemplary embodiment of the present disclosure, a size of the process film is the same as a size of the first side of the substrate.

[0016] In an exemplary embodiment of the present disclosure, a size of the process film is smaller than a size of the first surface of the substrate.

[0017] In an exemplary embodiment of the present disclosure, the process film is formed only on a peripheral area of ​​the first surface and / or a peripheral area of ​​the second surface of the substrate.

[0018] In an exemplary embodiment of the present disclosure, in the peripheral region of the first surface and / or the peripheral region of the second surface of the substrate, the thickness of the process film at different locations is different.

[0019] In an exemplary embodiment of the present disclosure, the process film is formed only in the core region of the first surface and / or the core region of the second surface of the substrate, and the process film has a uniform thickness.

[0020] According to a second aspect of the present disclosure, a method for manufacturing a mask is provided, comprising: providing a substrate, the substrate having a first surface and a second surface arranged opposite to each other, the first surface being a surface having a pattern; performing line width dimension correction on the substrate; measuring a deformation curvature radius of the substrate, and determining a shape, a type, a thickness and a formation area of ​​a process film according to the deformation curvature radius and process parameters of the substrate; forming a process film on the first surface and / or the second surface of the substrate according to the thickness, shape, type and formation area of ​​the process film to ensure that the substrate is restored to a horizontal state along a first direction.

[0021] The disclosed embodiment forms a process film on the substrate of the mask, which can correct the deformation of the substrate and keep the substrate flat while improving the strength of the line width correction of the mask, thereby allowing high-strength line width correction of the substrate and improving the processing accuracy of the mask.

[0022] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0024] Figure 1 Schematic diagram of the structure of a mask in an exemplary embodiment of the present disclosure.

[0025] Figure 2 The figure is a flow chart of a method for manufacturing a mask in one embodiment of the present disclosure.

[0026] Figure 3 It is a functional schematic diagram of the process pixel.

[0027] Figure 4 It is a schematic diagram of forming process pixel points in one embodiment of the present disclosure.

[0028] Figure 5 It is a schematic diagram showing deformation of a substrate after setting process pixel points in an embodiment of the present disclosure.

[0029] Figure 6A to Figure 6E It is a schematic diagram of the method of forming the process film in the embodiment of the present disclosure.

[0030] Figure 7A to Figure 7D It is a schematic diagram of the process film formation area.

[0031] Fig. 8A and Figure 8B It is a schematic diagram of the formation process of the process film. DETAILED DESCRIPTION

[0032] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the examples set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be more comprehensive and complete, and the concepts of the example embodiments are fully conveyed to those skilled in the art. The described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced while omitting one or more of the specific details, or other methods, components, devices, steps, etc. may be adopted. In other cases, known technical solutions are not shown or described in detail to avoid obscuring various aspects of the present disclosure.

[0033] In addition, the accompanying drawings are only schematic diagrams of the present disclosure, and the same reference numerals in the drawings represent the same or similar parts, so their repeated description will be omitted. Some of the block diagrams shown in the accompanying drawings are functional entities, which do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0034] The exemplary embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0035] Figure 1 Schematic diagram of the structure of a mask in an exemplary embodiment of the present disclosure.

[0036] refer to Figure 1 , the mask 100 may include:

[0037] A substrate 1 has a first surface and a second surface opposite to each other, the first surface is a surface with a pattern, a plurality of process pixel points 10 for line width correction are arranged inside the substrate 1, the plurality of process pixel points 10 are arranged along a first direction, the first direction is parallel to both the first surface and the second surface, and the distance between the plurality of process pixel points and the second surface is greater than the distance between the plurality of process pixel points and the first surface;

[0038] The process film 2 is formed on the first surface or the second surface of the substrate 1 to ensure that the substrate 1 recovers to a horizontal state along the first direction.

[0039] The substrate 1 is a quartz substrate. When manufacturing a mask, firstly, a pattern of the photolithography process is designed, and then a metal film (usually a metal such as chromium or platinum) is coated on the first surface of the quartz substrate 1, and a method such as electron beam evaporation or physical vapor deposition is used to form a designed pattern on the metal film to fix the pattern on the metal film.

[0040] The process pixel point 10 is formed by micro-processing the lattice of the quartz mask using a laser to change the refractive index of the substrate 1, so that a part of the light is scattered outside the through hole of the scanning lens, and the intensity of the light is reduced to change the critical dimensions formed by the substrate 1. This is because the intensity of the light source directly affects the exposure dose of the photoresist, thereby affecting the critical dimensions in the chip manufacturing process. Photoresist is a photosensitive material used in chip manufacturing. It can react chemically under the action of light to form the graphics and structure of the chip. During the photolithography process, the light source will irradiate the mask, and then project the graphics onto the photoresist through the lens to cause a chemical reaction. The greater the intensity of the light source, the greater the exposure dose of the photoresist, the stronger the chemical reaction, and the larger the chip graphics and structure formed. Therefore, by controlling the intensity of the light source, the exposure dose of the photoresist can be adjusted, thereby controlling the critical dimensions in the chip manufacturing process, such as line width, spacing, shape, etc. Controlling the intensity of the light source can adjust the critical dimensions.

[0041] In the embodiment of the present disclosure, the distance between the plurality of process pixel points and the first surface is less than or equal to 300 μm.

[0042] Figure 2 The figure is a flow chart of a method for manufacturing a mask in one embodiment of the present disclosure. Figure 2 The method shown can be used to manufacture a mask according to any embodiment of the present disclosure.

[0043] refer to Figure 2 In the embodiment of the present disclosure, the mask manufacturing method 200 may include:

[0044] Step S1, providing a substrate, wherein the substrate has a first surface and a second surface that are arranged opposite to each other, and the first surface is a surface having a pattern;

[0045] Step S2, correcting the line width of the substrate;

[0046] Step S3, measuring the deformation curvature radius of the substrate, and determining the shape, type, thickness and formation area of ​​the process film according to the deformation curvature radius and process parameters of the substrate;

[0047] Step S4, forming a process film on the first surface or the second surface of the substrate according to the shape, type, thickness and formation area of ​​the process film to ensure that the substrate is restored to a horizontal state along the first direction.

[0048] In step S2, the size correction of the substrate 1 may include obtaining a line width size correction amount of the substrate, and then micro-processing the lattice of the substrate according to the line width size correction amount to form a plurality of process pixel points. The plurality of process pixel points are arranged along a first direction, the first direction is parallel to both the first surface and the second surface, and the distance between the plurality of process pixel points and the second surface is greater than the distance between the plurality of process pixel points and the first surface.

[0049] Figure 3 It is a functional schematic diagram of the process pixel.

[0050] refer to Figure 3 In the substrate 1 provided with the process pixel 10, the light used for the photolithography process reaches the process pixel 10 after the first refraction at the second surface S2 (also called the mask glass surface) of the substrate 1, and the light intensity is partially shielded, and the remaining part reaches the first surface S1 (also called the pattern surface) of the substrate 1 after the second refraction at the process pixel 10, and reaches the wafer from the first surface S1 of the substrate 1. The angle of the second refraction is θ. When the material and process are consistent, the refractive index of the first surface S1, the second surface S2, and the process pixel 10 of the substrate 1 remains unchanged, and θ remains unchanged.

[0051] Assuming that the distance between the process pixel point 10 and the first surface S1 (also called the height of the process pixel point 10) is H, the processing size L2 finally formed on the wafer 20 is proportional to the coverage size L1 of the light on the first surface S1 and proportional to the height H of the process pixel point 10. Assuming L1=4L2, then L1 / 2H=tgθ, L2=(H tgθ) / 2, the larger H is, the larger the processing size L2 is, and the smaller H is, the smaller the processing size H2 is. Therefore, in order to make the processing accuracy more precise, it is necessary to set H as small as possible. For example, the process pixel point 10 is set at the center with a height of 3.175mm. If the process pixel point 10 is placed 300μm away from the first surface, the processing accuracy can be improved by 10 times, which is reduced by one order of magnitude, thereby further reducing the process size of lithography and being able to manufacture smaller chips.

[0052] Figure 4 It is a schematic diagram of forming process pixel points in one embodiment of the present disclosure.

[0053] refer to Figure 4 The steps of forming the process pixel point 10 may include:

[0054] Step 1.1: First, use the substrate to be corrected for exposure and collect wafer exposure CDU (Critical Dimension Uniformity) map data. The substrate to be corrected can be a substrate with a pattern formed for the first time, a substrate with line width problems after use, or a substrate that needs critical dimension calibration in other cases.

[0055] Step 1.2: Calculate the number of CDC pixels (process pixel points 10) that need to be inserted in the entire mask (substrate to be corrected) based on the wafer exposure CDU map data, and generate a pixel number map. Among them, the number of CDC pixels is inversely correlated with the CD (Critical Dimension) value. If the CD value needs to be reduced, the number of pixels is increased. The greater the reduction in the CD value, the more pixels there are.

[0056] Step 1.3: Load the substrate to be corrected onto the CDC tool table and set the height of the inserted pixel (process pixel point 10), which refers to the distance from the first surface of the substrate etched with the pattern, such as Figure 2 H in.

[0057] Step 1.4: Set a constant laser power for the CDC tool and insert pixels of different densities at different locations according to the pixel number map (process pixel point 10).

[0058] like Figure 4 As shown, after the process pixel 10 is formed, if the process pixel 10 is placed in a non-central position, stress deformation will occur due to asymmetric expansion, resulting in a pattern placement error, which will cause a wafer overlay error to deteriorate during photolithography.

[0059] In the embodiment of the present disclosure, in order to improve the processing accuracy, the distance between the process pixel point 10 and the first surface S1 is set to be smaller than the distance between the process pixel point 10 and the second surface S2. Therefore, after the line width dimension of the substrate is corrected in step S2, the deformation curvature radius R of the substrate can be measured in step S3, and the shape, type, thickness and formation area of ​​the process film can be determined according to the deformation curvature radius R and the process parameters of the substrate.

[0060] Figure 5 It is a schematic diagram showing deformation of a substrate after setting process pixel points in an embodiment of the present disclosure.

[0061] refer to Figure 5 From the top view of the substrate 1, the substrate 1 has a core area 51 where a pattern is set and a peripheral area 52 where no pattern is set. After the process pixel points 10 are set in the substrate 1, the height of each part of the substrate 1 is measured using a detection instrument, and the height of each area is marked according to the color. In the embodiment of the present disclosure, the darker the color, the smaller the height, which means the more concave; the lighter the color, the larger the height, which means the more convex. Figure 5 As shown, the area where the process pixel point 10 is provided is recessed, so that the substrate 1 is deformed to be recessed in the center and convex around.

[0062] Generally, the deformation of the substrate 1 is uniform radially from the center to the surroundings. By measuring the height of each part of the substrate 1, the overall deformation curvature radius of the substrate 1 can be obtained.

[0063] In some special cases, if the number of process pixel points at a certain location of the substrate 1 is much greater than that at other locations, it may also result in different degrees of deformation and different deformation curvature radii at different locations of the substrate 1 .

[0064] Next, the shape, type, thickness, formation area, and formation method of the process film may be determined according to the specific deformation of the substrate 1 .

[0065] Figure 6A to Figure 6E It is a schematic diagram of the method of forming the process film in the embodiment of the present disclosure.

[0066] refer to Fig. 6A In one embodiment, the process film 2 is formed on the first surface S1 of the substrate 1 , and the process film is a shrink film for tightening the first surface S1 .

[0067] If the process pixel point 10 is placed at a non-central position, the substrate 1 will bulge and bend toward the first surface S1. Therefore, in the embodiment of the present disclosure, a shrink film is provided on the first surface S1 to tighten the first surface S1, correct the bulge of the first surface S1, restore it to flatness, and then maintain the flatness of the substrate 1. The flatness of the embodiment of the present disclosure means that the deformation of each area of ​​the substrate 1 is within a certain range, for example, the maximum deformation curvature radius R of the substrate 1 is reduced to below a preset value, and it is not necessarily absolutely flat.

[0068] refer to Figure 6B In another embodiment, the process film 2 is formed on the second surface S2 of the substrate 1, and the process film is a tension film for stretching the second surface S2. By setting the tension film on the second surface S2 to stretch the second surface S2, the depression of the second surface S2 can be corrected to restore it to flatness, thereby correcting the substrate 1 to restore it to flatness.

[0069] In yet another embodiment, in order to enhance stress and better correct deformation of the substrate 1 , a shrinkage film and a tension film may be formed simultaneously on the first surface and the second surface of the substrate 1 .

[0070] refer to Figure 6C The process film may include a first process film 21 and a second process film 22 , wherein the first process film 21 is formed on the first surface of the substrate, and the second process film 22 is formed on the second surface of the substrate 1 .

[0071] In one embodiment, the first process film 21 is a shrink film, and the second process film 22 is a tension film. By forming corrective stress on the substrate 1 from two surfaces, the substrate 1 can be better restored to flatness.

[0072] In another embodiment, the first process film 21 and the second process film 22 may both be shrinkage films, or may both be tension films.

[0073] When the process film 2 covers the core area of ​​the substrate 1 where the pattern is set, it will form a light intensity attenuation effect on the incident laser. In order to overcome this defect, the thickness of the process film 2 needs to be strictly limited so that the existence of the process film 2 has the smallest effect on the light intensity. This limitation on the film thickness is referred to as the maximum film thickness below. If the calculated stress of the substrate 1 is large, a single layer of shrinkage film or a layer of tension film is used to correct the deformation, and the film thickness that needs to be set may exceed the maximum film thickness. Therefore, in the embodiment of the present disclosure, two process films are used to correct the deformation of the substrate 1.

[0074] Shrink films can be divided into different types according to different unit stresses, and tension films can also be divided into different types according to different unit stresses. Therefore, in order to reduce the total film thickness, a shrink film or tension film with a larger unit stress can be used to correct the deformation of the substrate 1. However, when the film formation area is constant, the smaller the film thickness and the larger the unit stress of the film, the greater the possibility of film fracture. Therefore, different types of shrink films and tension films have corresponding minimum film thickness restrictions, which are referred to as minimum film thickness below.

[0075] Assume that the stress that the current process film needs to provide is x, and the formation area is S. Under the maximum film thickness limit, the shrink film A is selected to provide the correction stress to the first surface of the substrate 1. However, when the film thickness of the shrink film A is set to its corresponding minimum film thickness, the stress y provided by the shrink film A when the formation area is S is still greater than x, that is, the shrink film A will still over-correct the substrate 1 even when it is at its minimum film thickness. At this time, the stress of the substrate 1 can be balanced by forming a layer of shrink film B on the second surface of the substrate 1. The stress provided by the shrink film B when the formation area is S is z, so that x+z=y, and finally the sum of the thickness of the shrink film B and the thickness of the shrink film A is controlled to be less than the maximum film thickness limit.

[0076] The principle of forming the tension membrane on both the first surface and the second surface is the same as above and will not be described in detail.

[0077] By forming films of the same type but with different stresses on the first and second surfaces of the substrate 1, the total thickness of the process film can be limited within a preferred range, so that the presence of the process film does not affect the light transmittance of the mask as much as possible, and each layer of the process film has good strength and is not easy to break.

[0078] In addition to forming the same type of film on the first surface and the second surface, two layers of film may be formed on the first surface or the second surface to achieve the above-mentioned purpose of controlling the film thickness.

[0079] refer to Fig.6D In one embodiment, the first process film 21 and the second process film 22 are stacked and formed on the first surface of the substrate 1 .

[0080] In one case, the first process film 21 is a shrink film, and the second process film 22 is a tension film.

[0081] In order to control the film thickness not to exceed the maximum film thickness, a process film with a larger unit stress may be selected. However, when the range of available process films is limited, if the unit stress of the process film exceeds a certain value, even if the film thickness is set to the minimum film thickness that does not break the film, the stress provided by the process film is greater than the deformation stress of the substrate 1. To this end, one method is as follows Figure 6C As shown, a shrinkage film is attached to the second surface of the substrate 1 to balance the stress. Another method is to reduce the stacking stress of the process film by forming another tension film (second process film 22) on the first process film 21 with greater stress, so as to achieve the purpose that the thickness of the single-layer film is not less than the minimum film thickness corresponding to each layer of the film and the total thickness of the double-layer film is not greater than the maximum film thickness allowed by the mask.

[0082] In another case, two shrinkage films with different unit stresses may be selected to cooperate to achieve the above purpose. The first process film 21 and the second process film 22 may both be shrinkage films.

[0083] In the case of a limited range of process film types, if the thickness of the A film with a larger unit stress is strictly limited due to some reason (such as transmittance, etc.), even if the maximum allowable film thickness is used to form the process film, the stress provided by it is still insufficient to correct the deformation of the substrate 1. The B film with a smaller unit stress, even if the maximum film thickness allowed by the mask is reached, the stress provided by it is still insufficient to correct the deformation of the substrate 1. At this time, these two process films can be used together to achieve stress matching, for example, first forming the A film according to the maximum allowable film thickness of the A film, and then forming the B film to supplement the stress, and finally correcting the deformation of the substrate 1 by superimposing the A film and the B film.

[0084] Fig.6D The overlapping forms of the films shown are only examples. In actual applications, the first process film 21 can be set as a tension film and the second process film 22 can be set as a compression film, or the unit stress of the first process film 21 can be set to be smaller than the unit stress of the second process film 22. Those skilled in the art can make adjustments according to the type of process film actually used.

[0085] refer to Fig. 6E In another embodiment, the first process film 21 and the second process film 22 are stacked and formed on the second surface of the substrate 1 .

[0086] and Fig.6D The principle of the embodiment shown is the same. In one case, the stress provided by the first process film 21 as a tension film is relatively large. In order to balance the stress, a method is as follows Figure 6CAs shown, a tension film is also adhered to the first surface of the substrate 1 to balance the stress. Another method is to form a shrinkage film (second process film 22) on the first process film 21 to reduce the stacking stress of the process film, thereby achieving the purpose that the thickness of the single-layer film is not less than the minimum film thickness corresponding to each layer of the film and the total thickness of the double-layer film is not greater than the maximum film thickness allowed by the mask.

[0087] Correspondingly, Fig.6D The principle of the embodiment shown is the same, the first process film 21 and the second process film 22 can also be tension films, and the unit stress is different. By superimposing the first process film 21 and the second process film 22, a correction stress is provided to the substrate 1, and the film thickness limit of the single layer film and the total film thickness limit are met at the same time.

[0088] Fig. 6E The overlapping forms of the films shown are only examples. In actual applications, the first process film 21 can be set as a compression film and the second process film 22 can be set as a tension film, or the unit stress of the first process film 21 can be set to be greater than or less than the unit stress of the second process film 22. Those skilled in the art can make adjustments according to the type of process film actually used.

[0089] In addition to adjusting the type of film, the deformation of the substrate 1 by the process film can also be adjusted by setting different formation areas.

[0090] Figure 7A to Figure 7D It is a schematic diagram of the process film formation area. Figure 7A to Figure 7D The process membranes mentioned include Figure 6A to Figure 6E The situations mentioned in the text, such as the process membrane being set up individually or in combination, are collectively referred to as process membranes below.

[0091] refer to Fig. 7A In one embodiment, the process film (whether formed by stacking or separately) can be formed on the entire first surface and / or the entire second surface of the substrate 1. The substrate 1 is rectangular and has a core area 71 for setting a pattern and a peripheral area 72 for fixing or other functions. When the process film is formed on the entire first surface and / or the entire second surface of the substrate 1, the core area 71 and the peripheral area 72 both form the process film, and the film thickness at each location can be the same or different according to the stress detection result of the substrate 1.

[0092] Since the core region 71 is provided with a pattern for performing a photolithography operation, the film thickness of the core region 71 must be kept uniform even if the film thickness varies in different places, and the total thickness of the film cannot be greater than the maximum film thickness described above. The thickness of the process film at different positions in the peripheral region 72 may be different to correct different stresses in different regions of the substrate 1.

[0093] Forming the entire process film on the entire first surface and / or the entire second surface of the substrate 1 can provide maximum stress when the film thickness is limited. When the film thickness is uniform everywhere, it can provide more uniform stress, making the substrate 1 smoother and the process film have better adhesion.

[0094] refer to Figure 7B and Figure 7C In another embodiment, in order to prevent the formation of the process film from affecting the light transmission of the core area 71, the process film can be formed only on the peripheral area 72. The advantage of this is that it is not limited by the maximum film thickness, but the disadvantage is that it is difficult to provide deformation correction for the core area 71, and the overall deformation correction effect is limited.

[0095] exist Figure 7B , a process film can be formed in the entire peripheral area 72, Figure 7C , a process film may also be formed in a partial area of ​​the peripheral area 72 according to the stress detection result of the substrate 1 .

[0096] exist Figure 7B If the process film is formed entirely in the peripheral area 72, the thickness of the process film in different areas may be different. The process film formed in the area with greater deformation in the substrate 1 may be thicker, and the process film formed in the area with smaller deformation may be thinner.

[0097] exist Figure 7C If a process film is formed in a partial area of ​​the peripheral area 72, the thickness and area of ​​the process films in different areas may be different. Technical personnel in this field can obtain different process film formation strategies based on actual working condition tests, thereby achieving stress correction for the entire substrate 1 by correcting the deformation of the peripheral area 72.

[0098] refer to Fig.7D In other embodiments, since the deformation of the substrate 1 is caused by the process pixels added to the core area 1, a process film may be formed only on the core area 1 to correct the deformation caused by the process pixels. When the process film is formed on the core area 1, the formed area needs to be equal to the area of ​​the core area 1, and the thickness of the process film at each location is the same to avoid uneven light transmission of the mask.

[0099] Regardless of which method is used to form the process film, the position, thickness and area of ​​the process film need to be calculated based on the actual deformation (stress) detection results of the substrate 1 after setting the process pixel points and the types of process films that can be selected.

[0100] In one embodiment, the process film 2 is a transparent inorganic film, and the material of the inorganic film includes but is not limited to silicon nitride, silicon oxide, and indium tin oxide. The process film 2 can be sputtered by PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) process. PVD is a physical vapor deposition technology that heats a solid material to a high temperature, evaporates or sputters it into a gas or ion, and then deposits it on the surface of the substrate to form a thin film. During the PVD process, the evaporated or sputtered material is deposited on the substrate in the form of atoms or molecules to form a thin film. PVD technology can be used to deposit materials such as metals, alloys, and oxides. Common PVD methods include evaporation, sputtering, and ion plating. CVD is a chemical vapor deposition technology that introduces a gas or a gas mixture into a reaction chamber to cause a chemical reaction on the surface of the substrate to generate a solid product and deposit it on the substrate to form a thin film. During the CVD process, the chemical substances in the gas or gas mixture react chemically on the surface of the substrate to generate a solid product and deposit it to form a thin film. CVD technology can be used to deposit materials such as metals, alloys, nitrides, carbides, etc. Common CVD methods include thermal CVD, low-pressure CVD, and plasma-enhanced CVD. In general, PVD is a physical method of converting materials from solid to gaseous state and then depositing them on a substrate, while CVD is a method of depositing gases or gas mixtures on a substrate through chemical reactions. PVD is more suitable for the deposition of metals and alloys, while CVD is more suitable for the deposition of compound materials.

[0101] In another embodiment, the process film 2 is an organic film, such as a polymer resin film. In this case, the process film 2 can be deposited by CVD or coated by a coating tool and cured by an oven tool.

[0102] Fig. 8A and Figure 8B It is a schematic diagram of the formation process of the process film.

[0103] Fig. 8A The figure shows the process of uniformly forming the process film 2 (shrink film) on the first surface of the substrate 1.

[0104] exist Fig. 8A In the process shown, after the line width dimension of the substrate 1 is corrected in step S2, the substrate 1 is bent. At this time, step S3 is entered to measure the deformation curvature radius R of the substrate 1, and the thickness of the process film is determined according to the deformation curvature radius R and the process parameters of the substrate, see formulas (1) to (3). The deformation curvature radius R is measured, for example, by using a rangefinder to measure, calculate the height of each measurement point, and thus calculate the flatness or curvature of the entire surface.

[0105] The process film 2 needs to form the same stress as the bending of the substrate 1 in order to correct the bending of the substrate 1. The film material can be attached to the surface of the substrate 1 by sputtering, deposition, etc. to form a film with internal stress, namely the process film 2. Due to the difference in materials and process conditions between the process film 2 and the substrate 1, the stress magnitudes are different.

[0106] Assume that the bending stress of substrate 1 is σ s , and its calculation formula is formula (1):

[0107]

[0108] Among them, E s is the elastic modulus of substrate 1, I s is the section moment of inertia of substrate 1, V s is the Poisson's ratio of the material of substrate 1, t s is the thickness of substrate 1, and R is the deformation curvature radius of substrate 1, which can be measured by a measuring instrument. When determining the deformation curvature radius R, firstly, process pixel points 10 can be added to substrate 1 according to the ideal height H (without considering the deformation of substrate 1). The setting of process pixel points 10 will cause the deformation curvature radius R of substrate 1. At this time, the deformation curvature radius R can be measured using tools such as a rangefinder, and brought into formula (1) together with the various parameters of substrate 1 to calculate the bending stress of substrate 1. Then, the parameters of the process film are determined according to the subsequent calculation method, and process film 2 is formed on substrate 1. In addition to using formula (1) to calculate the stress of substrate 1, the stress of substrate 1 can also be directly measured by instruments such as laser interferometers.

[0109] Since the number and position of the process pixel points 10 are different, the influence on the substrate 1 is different, and the process pixel point 10 is determined based on the CD value that actually needs to be corrected. Therefore, the deformation curvature radius R needs to be actually measured before forming the process film each time.

[0110] Determine the bending stress σ of substrate 1 s After that, it is necessary to determine the process parameters of process film 2. According to the equilibrium condition of bending stress, we have:

[0111] σ s =σ f (2)

[0112] Among them, σ f is the bending stress of the process film 2.

[0113] According to the Stoney formula for calculating film stress, we have:

[0114]

[0115] The Stoney formula is a formula used to calculate the strain of a film or coating when it is subjected to a force, that is, the degree of surface bending of the film or coating. f is the thickness of process film 2.

[0116] The film thickness is obtained from

[0117] Fig. 8A The process film 2 shown can completely cover the pattern 11 on the first surface S1 during the formation process.

[0118] After forming the process film 2, the flatness of the substrate 1 is measured again to determine whether the substrate 1 is restored to flatness. After determining whether the substrate 1 is restored to flatness, a protective structure 3 is formed on the portion of the process film 2 close to the wafer.

[0119] Since the protection structure 3 needs to be fixed on the substrate 1 by pasting, Fig. 8A In the process shown, the process film 2 can be arranged to be formed only in the area outside the bonding position of the protection structure 3 and the substrate 1 to ensure the smooth arrangement of the protection structure 3. This factor needs to be taken into account when calculating the film thickness.

[0120] Figure 8B The figure shows the process of uniformly forming the process film 2 (tension film) on the second surface of the substrate 1.

[0121] The process film 2 formed on the second surface S2 and Fig. 8A The thickness of the process film 2 formed on the first surface S1 in the illustrated embodiment is calculated in the same manner and will not be described in detail herein.

[0122] and Fig. 8A Compared with the embodiment shown, Figure 8B The process film 2 will not touch the pattern 11 on the first surface S1 during the formation process, so the formation efficiency is higher, the flatness is better, and the process is easier to implement.

[0123] After forming the process film 2, the flatness of the substrate 1 is measured again to determine whether the substrate 1 is restored to flatness. After determining whether the substrate 1 is restored to flatness, a protective structure 3 is formed on the portion of the process film 2 close to the wafer.

[0124] Since the protective structure 3 can still be installed on the first surface of the substrate 1 at this time, it is only necessary to form the process film 2 normally on the second surface of the substrate 1. Figure 8B The process membrane setting method is compared with Fig. 8A The process membrane setting method is simpler.

[0125] The substrate 1 provided with the process film 2 can be restored to flatness, overcoming the curvature caused by the setting of the process pixel point 10. Therefore, the embodiment of the present disclosure can place the process pixel point 10 below the center position, thereby obtaining a smaller processing size. Compared with the relevant technology, the processing accuracy of the mask provided by the embodiment of the present disclosure is currently at the level of hundreds of microns. If the height H of the placement position of the process pixel point 10 is reduced by 10 times during the CDC process, the processing accuracy will increase by 10 times to the level of ten microns, and the degree of reduction of the critical size of the wafer will be greatly increased.

[0126] It should be noted that, although several modules or units of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to the embodiments of the present disclosure, the features and functions of two or more modules or units described above can be embodied in one module or unit. On the contrary, the features and functions of one module or unit described above can be further divided into multiple modules or units to be embodied.

[0127] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are to be considered exemplary only, and the true scope and concept of the present disclosure are indicated by the claims.

Claims

1. A mask, characterized in that: include: A substrate having a first surface and a second surface opposite to each other, wherein the first surface is a surface having a pattern, and a plurality of process pixel points for line width dimension correction are arranged inside the substrate, wherein the plurality of process pixel points are arranged along a first direction, the first direction is parallel to both the first surface and the second surface, and the distance between the plurality of process pixel points and the second surface is greater than the distance between the plurality of process pixel points and the first surface; A process film is formed on the first surface and / or the second surface of the substrate to ensure that the substrate is restored to a horizontal state along the first direction.

2. The mask according to claim 1, wherein: The process film is a shrinkage film, which is formed on the first surface of the substrate and used to tighten the first surface, or the process film is a tension film, which is formed on the second surface of the substrate and used to extend the second surface.

3. The mask according to claim 1, wherein: The process film includes a first process film and a second process film.

4. The mask according to claim 3, characterized in that: The first process film is formed on the first surface of the substrate, and the second process film is formed on the second surface of the substrate.

5. The mask according to claim 3, characterized in that: The first process film and the second process film are stacked and formed on the first surface of the substrate.

6. The mask according to claim 3, characterized in that: The first process film and the second process film are stacked and formed on the second surface of the substrate.

7. The mask according to any one of claims 4 to 6, characterized in that: The first process film is a shrink film, and the second process film is a tension film.

8. The mask according to claim 4 or 5, characterized in that: The first process film and the second process film are both shrink films.

9. The mask according to claim 4 or 6, characterized in that: The first process film and the second process film are both tension films.

10. The mask according to claim 1, wherein: The size of the process film is the same as the size of the first surface of the substrate.

11. The mask according to claim 1, wherein: The size of the process film is smaller than the size of the first surface of the substrate.

12. The mask according to claim 11, wherein: The process film is formed only on a peripheral area of ​​the first surface and / or a peripheral area of ​​the second surface of the substrate.

13. The mask according to claim 10 or 12, characterized in that: In the peripheral area of ​​the first surface and / or the peripheral area of ​​the second surface of the substrate, the thickness of the process film is different at different positions.

14. The mask according to claim 11, wherein: The process film is formed only in a core region of the first surface and / or a core region of the second surface of the substrate, and the process film has a uniform thickness.

15. A method for manufacturing a mask, characterized in that: Used to manufacture the mask according to any one of claims 1 to 14, comprising: Providing a substrate, the substrate having a first surface and a second surface arranged opposite to each other, wherein the first surface is a surface having a pattern; Performing line width dimension correction on the substrate; Measuring the deformation curvature radius of the substrate, and determining the shape, type, thickness and formation area of ​​the process film according to the deformation curvature radius and the process parameters of the substrate; The process film is formed on the first surface and / or the second surface of the substrate according to the shape, type, thickness and formation area of ​​the process film to ensure that the substrate is restored to a horizontal state along the first direction.

Images