Apparatus and method for improving mask bump etch uniformity

Abstract

The application provides a device and method for improving mask boss corrosion uniformity, and relates to the technical field of mask processing. The device comprises: a corrosion tank for containing a corrosion solution; a vacuum fixing mechanism arranged above the corrosion tank and used for fixing a to-be-corroded mask upside down by vacuum adsorbing the back surface of the to-be-corroded mask, so as to immerse a to-be-corroded surface of the to-be-corroded mask, on which a glue boss is formed, into the corrosion solution and corrode the area outside the glue boss, thereby forming a final boss on the to-be-corroded mask, wherein the immersion depth of the to-be-corroded surface satisfies that only the to-be-corroded surface is in contact with the corrosion solution, and a mask pattern is formed on the final boss.

Description

Technical Field

[0001] This application relates to the field of mask processing technology, specifically to the field of wet etching technology, and particularly to a device and method for improving the etching uniformity of mask bosses. Background Technology

[0002] Since surface plasmon super-resolution lithography is a near-field lithography, the distance between the mask and the substrate is very close, and the requirements for large-area PV undulations on the mask surface are high. Therefore, the contact area between the mask and the substrate can be reduced by creating protrusions with mask patterns on the mask surface, thereby improving the lithography quality.

[0003] In related technologies, a mask wet etching process can be used to create bosses on the mask surface. The conventional operation involves using tape to adhere to the back of the mask to protect it from corrosion by the etching solution during the wet etching process. The mask with the tape attached is then immersed in the etching solution for the conventional wet etching process.

[0004] However, traditional mask wet etching processes suffer from technical problems such as surface particle adhesion due to tape protection, corrosion solution contamination, and poor etching uniformity. Summary of the Invention

[0005] In view of this, embodiments of this application provide an apparatus and method for improving the corrosion uniformity of mask bosses, which can at least partially solve the above-mentioned technical problems.

[0006] One embodiment of this application provides an apparatus for improving the uniformity of etching of mask bosses, comprising: an etching tank for holding an etching solution; and a vacuum fixing mechanism disposed above the etching tank for fixing the mask to be etched by vacuum adsorption of the back side of the mask to be etched, so as to immerse the surface of the mask to be etched with adhesive bosses into the etching solution and etch the area other than the adhesive bosses, thereby forming a final boss on the mask to be etched, wherein the immersion depth of the surface to be etched is such that only the surface to be etched contacts the etching solution, and a mask pattern is formed on the final boss.

[0007] According to an embodiment of this application, it further includes: a rotary drive mechanism, rotatably connected to the vacuum fixing mechanism, used to drive the vacuum fixing mechanism to rotate at a preset speed, while simultaneously driving the mask to rotate in the etching solution.

[0008] According to an embodiment of this application, it further includes: an air blowing mechanism, the outlet of which points to the back of the mask, for blowing air onto the back of the mask to prevent the corrosive solution from splashing onto the back of the mask to be corroded or the gas after the corrosive solution evaporates from remaining on the back of the mask to be corroded.

[0009] Another embodiment of this application provides a method for improving the uniformity of mask boss corrosion, comprising: using a vacuum fixing mechanism to fix the mask to be etched by vacuum adsorption of the back side of the mask; controlling the surface of the mask to be etched, on which the adhesive boss is formed, to be immersed in the corrosion solution to a preset depth for corrosion of the area outside the adhesive boss; cleaning the etched surface to be etched to obtain a mask with a final boss, wherein a mask pattern is formed on the final boss.

[0010] According to an embodiment of this application, the method further includes: spin-coating photoresist onto a clean mask surface; exposing and developing the mask with the photoresist to form photoresist bumps in the patterned area of ​​the mask; and removing the photoresist outside the bumps to obtain the mask to be etched.

[0011] According to an embodiment of this application, it further includes: using a rotary drive mechanism to drive a vacuum fixing mechanism to rotate at a preset speed, thereby causing the mask to be etched to rotate in the etching solution, wherein the rotational speed of the rotary drive mechanism is 5 rpm to 100 rpm.

[0012] According to embodiments of this application, the method further includes: using an air blowing mechanism to blow air onto the back of the mask to prevent the corrosive solution from splashing onto the back of the mask to be etched or the gas from the evaporation of the corrosive solution from remaining on the back of the mask to be etched.

[0013] According to the embodiments of this application, the vacuum negative pressure value of the vacuum fixing mechanism for vacuum adsorbing the mask to be etched is greater than -30MPa; the preset depth of the surface to be etched into the etching solution is 0.5±0.3mm; and the etching time of the surface to be etched in the etching solution is 60min~120min.

[0014] Another aspect of this application provides a mask for surface plasmonic super-resolution lithography, wherein a boss is formed on the surface of the mask and a mask pattern is formed on the boss; the mask is prepared using the apparatus or method provided in this application.

[0015] According to an embodiment of this application, the length of the section of the boss edge parallel to the mask surface is 4mm~40mm, the width is 4mm~40mm, and the height of the boss edge perpendicular to the mask surface is 10μm~20μm.

[0016] The apparatus and method for improving the corrosion uniformity of mask bosses provided in this application have at least the following technical effects.

[0017] The vacuum fixing mechanism uses vacuum adsorption to fix the mask upside down, allowing only the surface of the mask with protrusions to be etched to contact the etchant solution. This achieves tape-free, full back protection, eliminating tape particle contamination at the source. This prevents tape particles from adhering to the mask surface and contaminating the etchant solution, ensuring the flatness of the mask's etched surface, reducing product defect rates, and decreasing the frequency of etchant solution replacement, thus lowering process consumable costs.

[0018] The mask is driven to rotate in the etching solution by a rotary drive mechanism. By controlling the rotation speed of the mask, the uniformity of contact between the etching solution and the mask surface is further optimized, thereby improving the overall etching accuracy.

[0019] By setting up an air blowing mechanism to blow air onto the back of the mask, a positive pressure zone is created on the back of the mask, preventing the etchant from seeping into the back from the edge gaps. This ensures that only the front boss area is corroded, further preventing the etchant from corroding the back of the mask and thus not affecting the flatness of the back of the mask.

[0020] The mask prepared using this device and method has high-quality bosses, which meet the high requirements of surface plasmon lithography for the PV undulation of the mask surface. In other words, the mask is well-suited for surface plasmon lithography. Attached Figure Description

[0021] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments of this application with reference to the accompanying drawings.

[0022] Figure 1 One of the structural diagrams of an apparatus for improving the corrosion uniformity of mask bosses according to an embodiment of this application is shown schematically.

[0023] Figure 2 The diagram illustrates a second structural diagram of a device for improving the corrosion uniformity of mask bosses according to an embodiment of this application.

[0024] Figure 3 A flowchart illustrating a method for improving the corrosion uniformity of mask bosses according to an embodiment of this application is shown schematically.

[0025] Figure 4 The diagram schematically illustrates the structural diagrams corresponding to each operation in the method for improving the corrosion uniformity of mask bosses according to embodiments of this application.

[0026] Figure 5A The diagram illustrates the height of the mask bosses obtained by etching a thin mask using a conventional wet etching process according to Embodiment 1 of this application.

[0027] Figure 5BThe diagram illustrates the height of the mask bosses obtained by etching a thinned mask plate according to the apparatus and method for improving the etching uniformity of mask bosses in Embodiment 1 of this application.

[0028] Figure 6A The diagram illustrates the height of the mask bosses obtained by etching an unthinned mask using a conventional wet etching process according to Embodiment 2 of this application.

[0029] Figure 6B The diagram illustrates the height of a mask boss obtained by etching an unthinned mask plate according to the apparatus and method for improving the etching uniformity of mask bosses in Embodiment 2 of this application. Detailed Implementation

[0030] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0031] In the process of developing this application, it was discovered that in traditional tape-protected wet etching processes, the etching solution used in wet etching undergoes a slight dissolution and peeling reaction with the protective tape, resulting in the formation of tiny particles from the tape. These particles directly adhere to the area of ​​the mask to be etched, affecting the process effect. The continuous shedding of tape particles and their mixing into the etching solution contaminates the solution, affecting its purity and thus reducing the stability of the etching process. Furthermore, this method is prone to uneven etching and inconsistent edge etching.

[0032] In view of this, embodiments of this application provide an apparatus and method for improving the uniformity of mask boss etching. The core design concept is inverted etching combined with vacuum adsorption fixation. The vacuum adsorption structure firmly fixes the back of the mask, achieving tape-free full back protection, allowing only the surface of the mask to be etched to contact the etching solution, thus eliminating tape particle contamination at the source. Simultaneously, a rotation drive structure is added during the etching process. By controlling the mask's rotation speed, the contact uniformity between the etching solution and the mask surface is further optimized, improving the overall etching accuracy. A detailed description is provided below with reference to the accompanying drawings and specific embodiments.

[0033] Figure 1 One of the structural diagrams of an apparatus for improving the corrosion uniformity of mask bosses according to an embodiment of this application is shown schematically.

[0034] like Figure 1As shown, the device for improving the corrosion uniformity of mask bosses in this application embodiment may include an corrosion tank 1 and a vacuum fixing mechanism 2.

[0035] Erosion tank 1 is used to hold the corrosion solution.

[0036] A vacuum fixing mechanism 2 is positioned above the etching tank 1. It is used to invert and fix the mask 4 to be etched by vacuum adsorption of the back side of the mask 4. This immerses the surface of the mask 4, where adhesive protrusions 5 are formed, into the etching solution, etching the area outside the adhesive protrusions and forming the final protrusions on the mask. The immersion depth of the surface to be etched is such that only the surface to be etched contacts the etching solution, and the final protrusions form the mask pattern.

[0037] In some embodiments, the material of the corrosion tank 1 can be a corrosion-resistant material, such as polypropylene (PP), polytetrafluoroethylene (PTFE), fluoropolymer-lined stainless steel, etc. The interior of the corrosion tank 1 forms a cavity for holding the corrosive solution.

[0038] In some embodiments, the etching solution can be determined according to the material of the mask, such as BOE (buffered oxide etchant), HF (silicon etching), KOH (anisotropic etching), H3PO4, etc.

[0039] In some embodiments, an overflow port may be provided above the corrosion tank 1 to maintain a constant liquid level and prevent inconsistent corrosion depth. A drain valve may be provided at the bottom of the corrosion tank 1 for easy replacement of the corrosion solution and cleaning of the corrosion tank 1.

[0040] In some embodiments, the opening size of the corrosion tank 1 is slightly larger than that of the mask, ensuring that the surface to be etched can be fully immersed after the mask is turned upside down, and that the liquid level is higher than the top of the boss.

[0041] In some embodiments, the vacuum fixing mechanism may include a substrate for providing rigid support. The substrate has a sealing groove and a vacuum hole array on its surface, and a vacuum interface on its side. An O-ring or a silicone sealing strip is embedded in the sealing groove to form a vacuum-sealed area. The vacuum hole array connects to a vacuum chamber beneath the substrate, generating suction force after evacuation. The vacuum interface is connected to a vacuum pump / generator to provide negative pressure.

[0042] Figure 2 The diagram illustrates a second structural diagram of a device for improving the corrosion uniformity of mask bosses according to an embodiment of this application.

[0043] like Figure 2As shown, the device for improving the corrosion uniformity of the mask boss in this embodiment may further include a rotary drive mechanism 3, which is rotatably connected to the vacuum fixing mechanism 2, for driving the vacuum fixing mechanism 2 to rotate at a preset speed, while simultaneously driving the mask 4 to rotate in the corrosion solution.

[0044] In some embodiments, the rotary drive mechanism 3 can be rotatably and detachably connected to the substrate of the vacuum fixing mechanism 2 to realize the rotation of the vacuum fixing mechanism 2.

[0045] It should be understood that rotation generates centrifugal force, preventing bubbles from remaining on the sides of the boss, thus avoiding the "air shield" blocking corrosion and eliminating localized under-etching. The exothermic corrosion creates a temperature gradient within the tank; rotation forces mixing, ensuring uniform temperature at all points and eliminating thermally driven rate differences. The accumulation of corrosion products (such as SiF4 and metal ions) on the surface inhibits the reaction; rotation carries these away, preventing self-inhibition. In other words, rotation uses forced convection to continuously replace the "used" etching solution on the surface, ensuring that every point on the mask is always immersed in "fresh, fully concentrated" etching solution, resulting in consistent corrosion depth and good uniformity.

[0046] In some embodiments, the apparatus for improving the corrosion uniformity of mask bosses may further include an air blowing mechanism, the outlet of which is directed toward the back of the mask, for blowing air toward the back of the mask to prevent the corrosive solution from splashing onto the back of the mask to be corroded or the gas after the corrosive solution evaporates from remaining on the back of the mask to be corroded, causing corrosion to the back of the mask.

[0047] For example, the blowing mechanism can be a nitrogen purge needle, which is a thin stainless steel tube that extends upward from the substrate and faces the opening on the back of the mask. Nitrogen is blown upward from the purge needle into the cavity on the back of the mask, creating a positive pressure zone on the back of the mask to prevent the etchant from seeping into the back from the edge gaps, ensuring that only the front boss area is etched.

[0048] Based on the above-described apparatus for improving the corrosion uniformity of mask bosses, embodiments of this application also provide a method for improving the corrosion uniformity of mask bosses.

[0049] Figure 3 A flowchart illustrating a method for improving the corrosion uniformity of mask bosses according to an embodiment of this application is shown schematically.

[0050] like Figure 3 As shown, the method for improving the corrosion uniformity of mask bosses in this application may include operations S301 to S303.

[0051] In operation S301, the vacuum fixing mechanism is used to fix the mask to be etched by vacuum adsorption of the back side of the mask.

[0052] In operation S302, the surface of the mask to be etched, which has adhesive protrusions, is immersed in the etching solution to a preset depth to etch the area outside the adhesive protrusions.

[0053] During the S303 process, the etched surface is cleaned to obtain a mask with the final boss.

[0054] In some embodiments, the method may further include: spin-coating photoresist onto a clean mask surface; exposing and developing the mask with the photoresist to form photoresist bumps in the patterned area of ​​the mask; and removing the photoresist outside the bumps to obtain the mask to be etched.

[0055] In some embodiments, the method may further include: using a rotary drive mechanism to drive a vacuum fixing mechanism to rotate at a preset speed, while simultaneously causing the mask to be etched to rotate in the etching solution.

[0056] In some embodiments, the method may further include: blowing air onto the back of the mask using an air blowing mechanism to prevent the corrosive solution from splashing onto the back of the mask to be corroded or the gas from the evaporation of the corrosive solution from remaining on the back of the mask to be corroded, thereby causing corrosion to the back of the mask.

[0057] Figure 4 The diagram schematically illustrates the structural diagrams corresponding to each operation in the method for improving the corrosion uniformity of mask bosses according to embodiments of this application.

[0058] For example, positive photoresist 402 can be spin-coated onto the surface of the clean mask 401 to obtain a structure as shown below. Figure 4 As shown in Figure a.

[0059] The positive photoresist 402 is exposed and developed to form photoresist protrusions 403 in the patterned area of ​​the mask 401. The photoresist outside the protrusions is removed to obtain the mask to be etched, and the resulting structure is as follows. Figure 4 As shown in b. This process requires ensuring that the adhesive does not peel off during the etching process.

[0060] The back of the mask to be etched is flattened and placed against the vacuum fixing mechanism. Vacuum adsorption is then activated, using the vacuum to adhere the back of the mask and secure it in an inverted position. The vacuum fixing mechanism maintains a negative pressure greater than -30 MPa on the mask to be etched, ensuring a firm and secure hold without any loosening.

[0061] With the etchable side of the mask facing down, slowly immerse it in the etching solution, controlling the immersion depth to 0.5±0.3mm. Only the front of the mask should be in complete contact with the etching solution; the back side should be purged with nitrogen gas to prevent solution contact and ensure the flatness of the mask's back side is maintained, thus preventing the exposure machine from failing to hold the mask. Start the rotary drive mechanism, setting a constant speed of 5rpm~100rpm to rotate the mask uniformly in the etching solution. Due to the protective effect of the adhesive bosses on the patterned area, etching only occurs on the areas outside the adhesive bosses. Remove a certain thickness from the areas not covered by the adhesive bosses, forming 404 bosses in the patterned area of ​​the mask. The resulting structure is shown below. Figure 4 As shown in c. Rotation ensures that the mask etching uniformity meets the requirements.

[0062] The rotational speed of the rotary drive mechanism can be determined based on the type of etching solution. For example, for isotropic wet etching (such as HF silica gel etching), the rotational speed can be 10-20 rpm; a slow rotation is sufficient for uniform etching, while a too-fast rotation will cause the etching solution to be splashed out. For anisotropic etching (such as KOH etching of silicon), the rotational speed can be 5-15 rpm; the etching rates on the crystal planes vary greatly, requiring extremely uniform etching. For metal etching (such as stainless steel pickling), the rotational speed can be 30-100 rpm; metal etching is rapid, requiring strong convection.

[0063] The rate at which the mask is immersed in the etching solution can be measured in advance, and the etching time can be set according to the required height to complete the wet etching process. The etching time can be 60 min to 120 min.

[0064] After etching is complete, the mask is lifted out of the etching solution, rinsed with pure water and dried by rotary evaporation, the vacuum adsorption is turned off, and the mask is removed. No tape is involved in the entire process, and no particulate pollution is generated.

[0065] Before removing the adhesive, a chromium film can be plated on the area outside the boss 404 to form an absorption layer 405, resulting in a structure as shown below. Figure 4 As shown in d.

[0066] After removing the photoresist from the boss surface and cleaning, a mask boss with a narrow and steep edge transition region is obtained, resulting in a mask with the final boss. The boss surface has the previously processed mask pattern, and the resulting structure is as follows. Figure 4 As shown in Figure e. To more clearly illustrate the apparatus and method for improving the corrosion uniformity of mask bosses provided in the embodiments of this application, specific embodiments are described below with reference to the accompanying drawings.

[0067] Example 1

[0068] In this embodiment 1, a thin-faced mask is used, which is a mask whose back side is hollowed out / thinned.

[0069] The thin mask is etched using a traditional wet etching process. The back of the mask is protected with tape, and the mask is placed in a fixture for etching. The etching solution is kept in a static state.

[0070] The apparatus and method for improving the corrosion uniformity of mask bosses according to the embodiments of this application are used to etch thin mask plates. A vacuum fixing mechanism is used to adsorb the back of the mask and has a rotation function to ensure that the mask rotates at a low speed and the corrosion liquid is in a flowing state.

[0071] Figure 5A The diagram illustrates the height of the mask bosses obtained by etching a thin mask using a conventional wet etching process according to Embodiment 1 of this application.

[0072] Figure 5B The diagram illustrates the height of the mask bosses obtained by etching a thinned mask plate according to the apparatus and method for improving the etching uniformity of mask bosses in Embodiment 1 of this application.

[0073] contrast Figure 5A and Figure 5B It can be seen that after etching the thin mask using the traditional wet etching process, the uniformity of mask etching is 0.568% when four points are measured at the edge of the boss. However, after etching the thin mask using the device and method of this application to improve the uniformity of mask boss etching, the uniformity of mask etching is 0.282% when four points are measured at the edge of the boss, thus improving the uniformity.

[0074] Example 2

[0075] This embodiment 2 uses an un-thinned mask.

[0076] Traditional wet etching process is used to etch an un-thinned mask. The back of the mask is protected with tape, and the mask is placed in a fixture for etching. The etching solution is in a static state.

[0077] The apparatus and method for improving the corrosion uniformity of mask bosses according to the embodiments of this application are used to etch unthinned mask plates. A vacuum fixing mechanism is used to adsorb the back of the mask and has a rotation function to ensure that the mask rotates at a low speed and the corrosion liquid is in a flowing state.

[0078] Figure 6A The diagram illustrates the height of the mask bosses obtained by etching an unthinned mask using a conventional wet etching process according to Embodiment 2 of this application.

[0079] Figure 6B The diagram illustrates the height of a mask boss obtained by etching an unthinned mask plate according to the apparatus and method for improving the etching uniformity of mask bosses in Embodiment 2 of this application.

[0080] contrast Figure 6A and Figure 6B It can be seen that after etching a thin mask using the traditional wet etching process, the uniformity of mask etching is 0.370% when measuring four points on the edge of the boss. However, after etching a thin mask using the device and method for improving the uniformity of mask boss etching according to the embodiments of this application, the uniformity of mask etching is 0.089% when measuring four points on the edge of the boss, thus improving the uniformity.

[0081] In summary, based on the data from Embodiments 1 and 2 above, it can be seen that the apparatus and method for improving the corrosion uniformity of mask bosses in this application eliminates the tape protection process and adopts a vacuum fixing mechanism to reduce the source of particles, simplify the process flow, reduce costs, and avoid mask damage caused by tearing the tape after corrosion. Simultaneously, the rotation function ensures liquid flow and corrosion uniformity, which better meets the requirements of high-precision mask manufacturing.

[0082] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this application is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this application, and all such substitutions and modifications should fall within the scope of this application.

Claims

1. A device for improving the corrosion uniformity of mask bosses, characterized in that, include: Etching tank, used to hold corrosive solutions; A vacuum fixing mechanism is provided above the etching tank. It is used to fix the mask to be etched by vacuum adsorption of the back side of the mask to be etched, so as to immerse the surface of the mask to be etched with adhesive protrusions into the etching solution and etch the area other than the adhesive protrusions, so as to form the final protrusion on the mask to be etched. The immersion depth of the surface to be etched is such that only the surface to be etched comes into contact with the corrosive solution, and a mask pattern is formed on the final protrusion.

2. The apparatus according to claim 1, characterized in that, Also includes: A rotary drive mechanism is rotatably connected to the vacuum fixing mechanism and is used to drive the vacuum fixing mechanism to rotate at a preset speed, while simultaneously causing the mask to be etched to rotate in the etching solution.

3. The apparatus according to claim 1, characterized in that, Also includes: An air blowing mechanism is provided, with its outlet pointing towards the back of the mask to be etched. The mechanism is used to blow air onto the back of the mask to prevent the corrosion solution from splashing onto the back of the mask or the gas from the evaporation of the corrosion solution from remaining on the back of the mask.

4. A method for improving the corrosion uniformity of mask bosses, characterized in that, include: A vacuum fixing mechanism is used to fix the mask to be etched by vacuum adsorption of the back side of the mask; The surface of the mask to be etched, which has adhesive protrusions, is immersed in the etching solution to a preset depth to etch the area outside the adhesive protrusions. The surface to be etched is cleaned and etched to obtain a mask with a final boss, wherein a mask pattern is formed on the final boss.

5. The method according to claim 4, characterized in that, Also includes: Spin-coat photoresist onto a clean mask surface; The photoresist-coated mask is exposed and developed to form photoresist bosses in the patterned area of ​​the mask. Remove the photoresist outside the area of ​​the photoresist boss to obtain the mask to be etched.

6. The method according to claim 4, characterized in that, Also includes: The vacuum fixing mechanism is driven by a rotary drive mechanism to rotate at a preset speed, thereby rotating the mask to be etched in the etching solution. The rotary drive mechanism rotates at a speed of 5 rpm to 100 rpm.

7. The method according to claim 4, characterized in that, Also includes: An air blowing mechanism is used to blow air onto the back of the mask to be etched, in order to prevent the corrosive solution from splashing onto the back of the mask or the gas from the evaporation of the corrosive solution from remaining on the back of the mask.

8. The method according to any one of claims 4 to 6, characterized in that, The vacuum fixing mechanism vacuum adsorbs the mask to be etched with a vacuum negative pressure value greater than -30MPa; The predetermined depth to which the surface to be corroded is immersed in the corrosive solution is 0.5 ± 0.3 mm; The corrosion time of the surface to be corroded in the corrosive solution is 60 min to 120 min.

9. A mask for surface plasmon super-resolution lithography, characterized in that, The mask surface has protrusions, and mask patterns are formed on the protrusions; the mask is prepared using the apparatus according to any one of claims 1 to 3 or the method according to any one of claims 4 to 8.

10. The mask according to claim 9, characterized in that, The length of the protrusion along the cross section parallel to the mask surface is 4mm~40mm, the width is 4mm~40mm, and the height of the protrusion along the cross section perpendicular to the mask surface is 10μm~20μm.

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