Surface plasma photoetching mask plate and preparation method thereof

Abstract

The invention relates to the field of surface plasma photoetching, in particular to a surface plasma photoetching mask and a preparation method thereof. Comprising a mask plate body, the mask plate body comprises a first surface and a second surface arranged on the opposite side of the first surface, a boss is arranged on the first surface, a groove is formed in the second surface, a transition surface is arranged between the top surface of the boss and the first surface, a barrier layer is arranged on the bottom surface of the groove, and the barrier layer is arranged on the first surface. And the barrier layer covers the orthographic projection area of the transition surface on the bottom surface of the groove. The groove is formed in the back surface of the mask plate, and the barrier layer is arranged in the orthographic projection area, corresponding to the boss transition inclined surface on the front surface of the mask plate, in the groove, so that the edge area of the mask boss can be effectively prevented from being imaged to the surface of a wafer during photoetching, imaging defects are reduced, and the photoetching quality is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of surface plasma lithography masks, and particularly to a surface plasma lithography mask and its preparation method. Background Technology

[0002] The core principle of surface plasmon lithography (SPL) is to utilize the near-field enhancement effect generated by surface plasmon polaritons (SPPs) or localized surface plasmon resonance (LSPR) on the metal-dielectric interface (usually a metal thin film) for patterning. Traditional lithography is limited by light diffraction; according to the Rayleigh criterion, CD = K1 × λ / NA, and the minimum feature size (CD) is limited by the wavelength of the light source (λ), the numerical aperture of the objective lens (NA), and the process factor (K1). SPL utilizes SPPs / LSPR to localize the light field energy within the subwavelength scale (much smaller than the incident light wavelength), thereby achieving super-resolution (subwavelength) lithography.

[0003] The basic process of surface plasmon lithography (SPL) mainly includes: incident light irradiating a specially designed metal mask, and the nanostructures on the mask (such as holes, slits, protrusions, etc.) exciting SPPs or LSPRs. These excited plasmas form highly localized near-field hotspots or specific light field distributions near the mask surface, with the characteristic size of their intensity distribution being much smaller than the incident wavelength. The photoresist (photosensitive material) placed close to the mask is exposed to these near-field hotspots. After development, nanopatterns with a resolution far exceeding that of traditional lithography are obtained on the photoresist.

[0004] Surface plasmon lithography (SPL) has advantages such as high resolution (up to 20 nm or even lower), relatively simple optical system, and potential low cost (compared to EUV lithography).

[0005] In near-field lithography (such as surface plasmon lithography (SP) and nanoimprint lithography (NIL)), the boss mask is a special type of mask used in SPL. Its core feature is that the mask surface has raised platform-like or columnar structures (boobs), and the boss surface contains a metal mask pattern structure.

[0006] As a core component for pattern transfer, photomasks face a series of key challenges. The following are the main problems currently existing with photomasks under near-field lithography conditions: The processing of boss masks mainly adopts wet etching or dry etching. The edges of the processed bosses often have large roughness, which leads to light leakage at the edges of the bosses in subsequent photolithography processes after the absorption layer is deposited. This will transfer the outline of the mask bosses to the substrate or wafer, affecting the quality of the photolithography pattern and failing to meet the requirements for multi-field exposure on the wafer. Summary of the Invention

[0007] (a) Technical problems to be solved The purpose of this invention is to overcome the technical defects in the prior art where the edges of the processed bosses often have large roughness, which leads to light leakage at the edges of the bosses during subsequent photolithography processes after the deposition of the absorption layer. This will transfer the mask boss outline to the substrate or wafer, affecting the quality of the photolithography pattern and failing to meet the requirements for multi-field exposure on the wafer.

[0008] (II) Technical Solution In a first aspect, the present invention provides a surface plasmon lithography mask, comprising a mask body, the mask body including a first surface and a second surface located on the opposite side of the first surface, a boss being provided on the first surface, the top surface of the boss having a mask pattern formed by an absorption layer; a groove being provided on the second surface, a transition surface being provided between the top surface of the boss and the first surface, and a blocking layer being provided on the bottom surface of the groove, the blocking layer covering the orthographic projection area of ​​the transition surface on the bottom surface of the groove.

[0009] Preferably, the barrier layer is arranged in a ring shape.

[0010] Preferably, the material of the barrier layer is capable of preventing light beams of 365nm and / or 193nm from passing through.

[0011] Preferably, the material of the barrier layer is resistant to acid corrosion.

[0012] Preferably, the barrier layer is any one of a chromium layer, a tantalum layer, or a molybdenum layer.

[0013] Preferably, the thickness of the barrier layer is 40-100 nm.

[0014] In a second aspect, the present invention provides a method for preparing the surface plasma lithography mask, comprising the following steps; S1. Divide the first surface of the mask body into regions according to the position of the mask pattern: wherein the mask pattern is located in the first region and the remaining regions are the second regions; S2. Based on the projection position of the first region on the second surface, a groove is prepared, wherein the orthographic projection area of ​​the groove on the first surface is greater than the area of ​​the first region. S3. Etch the second region to form a boss in the first region relative to the second region, and there is a transition surface between the first region and the second region; S4. A barrier layer is prepared on the bottom surface of the groove. The barrier layer is annular and covers the orthogonal projection area of ​​the transition surface on the bottom surface of the groove.

[0015] Preferably, in step S3, the depth of etching the second region to the height of forming the boss is 5-20 μm.

[0016] Preferably, step S3 further includes the following step: forming a second absorption layer on the surface of the etched second region, the second absorption layer being a metallic chromium layer, and the thickness of the second absorption layer being not less than 40 nm.

[0017] Preferably, step S4 includes the following steps: S41. A second photoresist layer is prepared on the first surface; the second photoresist layer covers the first region, the transition surface, and the second region. S42. The second photoresist layer is exposed by laser direct writing, and after development, a first groove ring is formed in the area corresponding to the transition surface of the boss. S43. Prepare a third photoresist layer on the bottom surface of the groove; S44. Irradiate the first surface with ultraviolet light, expose the third photoresist layer using the first groove ring, and after development, form a second groove ring in the corresponding area of ​​the third photoresist layer on the bottom surface of the groove. S45. Prepare a barrier layer in the second groove ring of the third photoresist layer, remove the remaining second and third photoresist layers, and complete the mask preparation.

[0018] (III) Beneficial Effects Compared with the prior art, the beneficial effects of the present invention are as follows: In the technical solution of the present invention, by setting a barrier layer in the groove on the back of the mask, the barrier layer can cover the projection area of ​​the protrusion transition surface of the mask on the bottom surface of the groove, effectively preventing the protrusion edge area of ​​the mask from being imaged onto the wafer surface during photolithography, reducing imaging defects and greatly improving the photolithography quality.

[0019] The technical solution of this invention directly and physically blocks light that may leak or scatter from the rough transition surface, ensuring that the carefully designed mask pattern on the top surface of the boss is exposed onto the photoresist. This effectively prevents the mechanical outline of the mask boss, rather than the designed circuit pattern, from being imaged onto the wafer substrate due to edge light leakage, thereby avoiding defects such as pattern distortion and edge burrs, and obtaining a photolithographic pattern with clear outline and extremely high fidelity.

[0020] The technical solution of this invention eliminates the instability caused by random light leakage at the edge of the photomask, ensuring the uniformity of all exposure field patterns on the entire wafer and providing a reliable guarantee for advanced processes.

[0021] The technical solution of this invention reduces the extreme dependence on the machining accuracy of the boss edge through innovative back-end structure design, widens the window of the front-end etching process, and improves the manufacturing yield and efficiency of the mask itself. Attached Figure Description

[0022] Figure 1 A schematic cross-sectional view of the surface plasmonic photolithography mask structure according to Embodiment 1 of the present invention is shown.

[0023] Figure 2 A schematic diagram of the barrier layer of the surface plasmonic photomask structure according to Embodiment 1 of the present invention is shown.

[0024] Figure 3 The diagram schematically illustrates the positional relationship between the barrier layer and the transition surface of the surface plasmon lithography mask structure according to Embodiment 1 of the present invention in the orthographic projection view of the bottom surface of the groove.

[0025] Figure 4 The diagram illustrates a top view of the surface plasmonic photolithography mask structure according to Embodiment 1 of the present invention.

[0026] Figure 5 The diagram illustrates the structure of the mask corresponding to each step of the method for preparing the surface plasmonic photolithography mask structure according to Embodiment 2 of the present invention (wherein, from top to bottom, it is a diagram of the structural change process of the mask body from S1 to S2).

[0027] Figure 6 The schematic diagram shows the structure of the mask corresponding to each step of the method for preparing the surface plasmonic photolithography mask structure according to Embodiment 2 of the present invention (wherein, from top to bottom, it is a diagram of the structural change process of S3-S41).

[0028] Figure 7 The schematic diagram shows the structure of the mask corresponding to each step of the method for preparing the surface plasmonic photolithography mask structure according to Embodiment 2 of the present invention (wherein, from top to bottom, it is a diagram of the structural change process of the mask body from S42 to S45).

[0029] Figure 8 A schematic diagram of the cross-sectional structure of the surface plasmon lithography mask structure of Comparative Example 1 is shown.

[0030] Figure 9The schematic diagram shows the expected effect obtained after photolithographic imaging of the surface plasmonic photomask structure of Example 1 and Comparative Example 1.

[0031] Explanation of reference numerals in the attached figures: 1-Mask version body; 100-First surface; 101-First region; 102-Second region; 200-Second surface; 2-First absorption layer; 3-First photoresist layer; 4-Groove; 5-Boss; 6-Second absorption layer; 7-Second photoresist layer; 8-Third photoresist layer; 9-Groove ring; 10-Blocking layer; 11-Transition surface light leakage profile; 12-Transition surface; 13-First groove ring. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0033] It should be noted that if the embodiments of this disclosure involve directional indication, the directional indication is only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0034] This invention provides a surface plasma lithography mask, such as... Figure 1-3 As shown, the mask includes a mask body 1, which is made of quartz material and has a thickness of 6-7 mm. The mask body 1 includes a first surface 100 and a second surface 200 disposed on the back side of the first surface 100. A boss 5 is provided on the first surface 100, with a vertical height of 5-20 μm. A groove 4 is provided on the second surface 200. A transition surface 12 is formed between the top surface of the boss 5 and the first surface 100. A blocking layer 10 is provided on the bottom surface of the groove 4, covering the orthographic projection area of ​​the transition surface 12 onto the bottom surface of the groove 4. This design does not rely on improving the difficult-to-handle edge topography on the front side, but rather intercepts stray light scattered or leaked from the rough transition surface by setting a physical barrier in the precisely projected area of ​​the optical path, further ensuring image quality.

[0035] Based on the above embodiments, the orthographic projection shape of the transition surface 12 within the groove 4 depends on the shape of the boss 5. Commonly used boss 5 shapes are circular or square. The orthographic projection shape of the transition surface 12 corresponding to a circular boss 5 is an annulus, and the orthographic projection shape of the transition surface 12 corresponding to a square boss 5 is a square annulus.

[0036] The shape of the blocking layer 10 also depends on the shape of the boss 5. The blocking layer 10 is a circular ring or a square ring. The blocking layer 10 and the orthographic projection shape of the transition surface 12 are concentrically arranged, and the orthographic projection area of ​​the blocking layer 10 covers the orthographic projection area of ​​the transition surface 12. The width of the blocking layer 10 is L1, and the width of the light leakage profile 11 formed on the transition surface is L2, and L1 > L2.

[0037] Based on the above embodiments, the height of the boss 5 is not less than 5μm. The distance between the bottom of the groove 4 and the boss 5 is 0.5-1.5mm.

[0038] The material of the barrier layer 10 has the following characteristics: it can prevent 365nm and / or 193nm light beams from passing through during photolithography, thus avoiding exposure on the photoresist, and it is resistant to acid corrosion. Based on the above embodiments, the thickness of the barrier layer 10 is 40-100nm, and the barrier layer 10 includes any one of a chromium layer, a tantalum layer, and a molybdenum layer. The barrier layer 10 is formed by magnetron sputtering or ion beam sputtering. Among them, chromium has a high extinction coefficient in the DUV band, and a very thin layer thickness can achieve complete light blocking, which meets the requirements of micro-nano processing. At the same time, it has good adhesion and corrosion resistance, making it the optimal choice in terms of overall performance.

[0039] This embodiment also discloses a method for preparing a surface plasma lithography mask, such as... Figure 4-6 As shown, it includes the following steps: S1. Divide the first surface 100 of the mask body 1 into regions according to the position of the mask pattern: wherein the mask pattern is located in the first region 101, and the remaining regions are the second region 102; the first region 101 is located in the middle of the first surface 100. In a more specific embodiment, the mask pattern is prepared as follows: a first absorption layer 2 is formed on the first surface 100, the first absorption layer 2 preferably being a chromium film with a thickness of 40 nm; the mask pattern is formed on the first absorption layer 2 by laser direct writing or electron beam direct writing and dry etching.

[0040] S2. Based on the projection position of the first region 101 on the second surface 200, a groove 4 is prepared, wherein the orthogonal projection area of ​​the groove 4 on the first surface 100 is greater than the area of ​​the first region 101. S3. A first photoresist layer 3 is formed on the surface of the first absorption layer 2. A first region 101 is formed on the first photoresist layer 3 by laser direct writing. A second region 102 is etched, forming a protrusion 5 between the first region 101 and the second region 102. A transition surface 12 is formed between the first region 101 and the second region 102. A second absorption layer 6 is formed on the surface of the etched second region 102 by magnetron sputtering. Then, the first photoresist layer 3 on the top surface of the protrusion 5 is removed by wet cleaning. The second absorption layer 6 is a chromium layer with a thickness of not less than 40 nm. The etching depth of the second region 102 to the height of the protrusion is 5 μm-20 μm. The protrusion height is a key parameter for achieving a low gap between the mask and the wafer during surface plasmon lithography imaging. The above height range can effectively reduce the gap and improve imaging quality.

[0041] In the technical solution of this embodiment, up to this step, that is, without setting the blocking layer 10, the transition surface 12 area connecting the top edge of the boss 5 and the second absorption layer 6 will leak light. As a result, during the photolithography process using this mask, the light-leaking area at the edge of the boss 5, other than the original photolithography pattern, will also form a pattern, affecting the exposure quality and failing to meet the requirements of multi-field photolithography.

[0042] S4. A barrier layer 10 is prepared on the bottom surface of the groove 4. The barrier layer 10 is annular and covers the orthographic projection area of ​​the transition surface 12 on the bottom surface of the groove 4.

[0043] Specifically, it includes the following steps: S41. A second photoresist layer 7 is prepared on the first surface 100; the second photoresist layer 7 covers the first region 101 and the second region 102; the thickness of the second photoresist layer 7 is not less than 10 μm. S42. Prepare a third photoresist layer 8 on the bottom surface of the groove 4; the thickness of the third photoresist layer 8 is 150nm-1μm; S43. The second photoresist layer 7 is exposed by laser direct writing, and after development, a first groove ring 13 is formed in the area corresponding to the transition surface 12 of the boss 5. S44. The first surface 100 is irradiated with ultraviolet light, and the third photoresist layer 8 is exposed using the first groove ring 13. After development, a second groove ring 9 is formed in the corresponding area of ​​the third photoresist layer 8 on the bottom surface of the groove 4; the pattern is slightly larger than the edge of the boss 5. S45. A barrier layer 10 is prepared in the second groove ring 9 of the third photoresist layer 8 by magnetron sputtering, and the remaining second photoresist layer 7 and third photoresist layer 8 are removed to complete the mask preparation.

[0044] In steps S41-S45 above, the front photoresist pattern is used as a mask, and the back barrier layer is precisely patterned by front light exposure. This method utilizes light to achieve sub-micron level high-precision replication between the front and back patterns, overcoming the challenge of double-sided alignment when the front and back markings cannot be seen simultaneously. Compared to mechanical alignment, it ensures better repeatability and is less costly.

[0045] Based on the above embodiments, there is another method for preparing the barrier layer 10: Specifically, a mask is set in the groove 4 region, and an annular region is set on the mask for photolithography, so that the corresponding position of the third photoresist layer 8 is developed and removed, and then a metal chromium film is deposited as a whole by magnetron sputtering, and then the third photoresist area in other regions of the groove 4 is cleaned off, thus obtaining the barrier layer 10.

[0046] Based on the above structure and preparation steps, the following two specific embodiments and one comparative example are provided.

[0047] Example 1: This embodiment provides a surface plasma lithography mask, such as... Figure 1-3 As shown, the structure includes a mask body 1, which is made of quartz and has a thickness of 6.5 mm. The mask body 1 includes a first surface 100 and a second surface 200. The first surface 100 has a boss 5 with a height of 10 μm. Corresponding to the boss 5, the second surface 200 has a groove 4 with a depth of 5.5 mm. The top surface area of ​​the boss 5 is 8.91 cm². 2 The bottom surface area of ​​groove 4 is 28.26 cm². 2 The ratio between the area of ​​the mask pattern on boss 5 and the surface area of ​​boss 5. For example... Figure 4 As shown.

[0048] There is a transition surface 12 between the top surface of the boss 5 and the first surface 100. A blocking layer 10 is provided in the orthographic projection area of ​​the transition surface 12 on the bottom surface of the groove 4, that is, at the position of the light leakage contour 11 of the formed transition surface.

[0049] Specifically, the top surface of the protrusion 5 has a first absorption layer 2, which is a metal film layer, specifically a chromium metal film. A designed mask pattern is etched on the chromium metal film, and the thickness of the first absorption layer 2 is 40nm.

[0050] A second absorption layer 6 is disposed on the first surface 100 of the mask, excluding the surface of the boss 5 and the other recessed surfaces. The second absorption layer 6 is also a chromium film and the thickness of the second absorption layer 6 is 40nm.

[0051] A groove 4 is provided on one side of the second surface 200 of the mask, and the groove 4 is coaxially arranged with the boss 5.

[0052] Specifically, the orthographic projection shape of the transition surface 12 within the groove 4 depends on the shape of the boss 5. In this embodiment, the boss 5 is square, and the orthographic projection shape of the transition surface 12 is a square ring.

[0053] The blocking layer 10 is specifically a chromium film. The material of the blocking layer 10 possesses the following properties: it can prevent the transmission of 365nm / 193nm light beams; it is resistant to acid corrosion. The blocking layer 10 is a square ring, and its shape is concentrically aligned with the orthographic projection of the transition surface 12. In this embodiment, the width of the square ring of the blocking layer 10 is 100-200μm. The thickness of the blocking layer 10 is 50nm.

[0054] Example 2: This embodiment discloses a method for preparing a surface plasma lithography mask, combined with... Figure 4-7 As shown, it includes the following steps; S1. Divide the first surface 100 of the mask body 1 into regions according to the position of the mask pattern: wherein the mask pattern is located in the first region 101, and the remaining regions are the second region 102; the first region 101 is located in the middle of the first surface 100; for example Figure 4 As shown; Specifically, the mask pattern is prepared as follows: a first absorption layer 2 is formed on the first surface 100, the first absorption layer 2 preferably being a chromium film with a thickness of 40 nm; the mask pattern is formed on the first absorption layer 2 by laser direct writing or electron beam direct writing and dry etching.

[0055] S2. Based on the projection position of the first region 101 on the second surface 200, a groove 4 is prepared, wherein the orthogonal projection area of ​​the groove 4 on the first surface 100 is greater than the area of ​​the first region 101. S3. A first photoresist layer 3 is formed on the surface of the first absorption layer 2. A first region 101 is formed on the first photoresist layer 3 by laser direct writing. A second region 102 is etched, so that the first region 101 forms a protrusion 5 relative to the second region 102. The first region 101 and the second region 102 have a transition surface 12. A second absorption layer 6 is formed on the surface of the etched second region 102 by magnetron sputtering. Then, the first photoresist layer 3 on the top surface of the protrusion 5 is removed by wet cleaning. The thickness of the second absorption layer 6 is not less than 40 nm. A second absorption layer 6 is prepared on the first surface 100 by magnetron sputtering. Then, the first photoresist layer 3 on the top surface of the protrusion 5 is removed by wet cleaning. The second absorption layer 6 is a chromium layer, and the thickness of the second absorption layer 6 is not less than 40 nm. Figure 6 As shown. The second region 102 is etched to a depth of 10 μm.

[0056] S4. A barrier layer 10 is prepared on the bottom surface of the groove 4. The barrier layer 10 is annular and covers the orthographic projection area of ​​the transition surface 12 on the bottom surface of the groove 4. Specifically, this includes the following steps: S41. A second photoresist layer 7 is prepared on the first surface 100; the second photoresist layer 7 covers the first region 101 and the second region 102; the thickness of the second photoresist layer 7 is not less than 10 μm. S42. Prepare a third photoresist layer 8 on the bottom surface of the groove 4; the thickness of the third photoresist layer 8 is 150nm-1μm; S43. The second photoresist layer 7 is exposed by laser direct writing, and after development, a first groove ring 13 is formed in the area corresponding to the transition surface 12 of the boss 5. S44. The first surface 100 is irradiated with ultraviolet light, and the third photoresist layer 8 is exposed using the first groove ring 13. After development, a second groove ring 9 is formed in the corresponding area of ​​the third photoresist layer 8 on the bottom surface of the groove 4; the pattern is slightly larger than the edge of the boss 5. S45. A barrier layer 10 is prepared in the second groove ring 9 of the third photoresist layer 8 by magnetron sputtering, and the remaining second photoresist layer 7 and third photoresist layer 8 are removed to complete the mask preparation.

[0057] Comparative Example 1: This comparative example provides a surface plasma lithography mask, such as... Figure 8 As shown, the structure is basically the same as that of Embodiment 1, except that the mask of Comparative Example 1 does not have a blocking layer 10.

[0058] To compare the effects of the two different photomasks, photolithographic imaging simulations were performed using the photomasks of Example 1 and Comparative Example 1, respectively, and the results are as follows. Figure 9 The diagram shown illustrates the expected outcome after photolithographic imaging. Figure 9 Middle, left side Figure 9 a shows the expected result of photolithographic imaging using the mask from Example 1, on the right. Figure 9 b shows the expected result of photolithography imaging using the mask of Comparative Example 1. The transition region exhibits a ring structure after imaging.

[0059] pass Figure 9 As can be seen, through the simulated photolithography imaging of the mask in Embodiment 1 of the present invention, no other non-mask patterns are involved except for the mask pattern, and the photolithography pattern can be accurately replicated on the wafer surface.

[0060] In the technical solution of the present invention, by setting a groove 4 on the back side of the mask, and then setting a barrier layer 10 in the groove 4 corresponding to the orthogonal projection area of ​​the transition slope of the protrusion 5 on the front side of the mask, it is possible to effectively prevent the edge area of ​​the mask protrusion 5 from being imaged onto the wafer surface during photolithography, thereby reducing imaging defects and greatly improving the photolithography quality.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A surface plasma lithography mask, characterized in that, The mask includes a mask body (1), which includes a first surface (100) and a second surface (200) located on the opposite side of the first surface (100). A boss (5) is provided on the first surface (100), and the top surface of the boss (5) has a mask pattern formed by an absorption layer. A groove (4) is provided on the second surface (200), and a transition surface (12) is provided between the top surface of the boss (5) and the first surface (100). A blocking layer (10) is provided on the bottom surface of the groove (4), and the blocking layer (10) covers the orthographic projection area of ​​the transition surface (12) on the bottom surface of the groove (4).

2. The surface plasma lithography mask according to claim 1, characterized in that, The barrier layer (10) is arranged in a ring shape.

3. The surface plasma lithography mask according to claim 2, characterized in that, The material of the barrier layer (10) is capable of preventing light beams of 365nm and / or 193nm from passing through.

4. The surface plasma lithography mask according to claim 3, characterized in that, The material of the barrier layer (10) is resistant to acid corrosion.

5. The surface plasma lithography mask according to claim 4, characterized in that, The barrier layer (10) is any one of a chromium layer, a tantalum layer, or a molybdenum layer.

6. The surface plasma lithography mask according to claim 5, characterized in that, The thickness of the barrier layer (10) is 40-100 nm.

7. A method for preparing a surface plasmonic photomask according to any one of claims 1 to 6, characterized in that, Includes the following steps; S1. Divide the first surface of the mask body into regions according to the position of the mask pattern: wherein the mask pattern is located in the first region (101), and the remaining regions are the second region (102). S2. Based on the projection of the first region (101) onto the second surface (200), a groove (4) is prepared, wherein the orthographic projection area of ​​the groove (4) on the first surface (100) is greater than the area of ​​the first region (101); S3. Etch the second region (102) to form a boss (5) in the first region (101) relative to the second region (102), and there is a transition surface (12) between the first region (101) and the second region (102). S4. A barrier layer (10) is prepared on the bottom surface of the groove (4). The barrier layer (10) is annular and covers the orthographic projection area of ​​the transition surface (12) on the bottom surface of the groove (4).

8. The method for preparing a surface plasma lithography mask according to claim 7, characterized in that, In step S3, the depth of etching the second region (102) to the height of forming the boss is 5-20 μm.

9. The method for preparing a surface plasma lithography mask according to claim 7 or 8, characterized in that, Step S3 further includes the following steps: forming a second absorption layer (6) on the surface of the etched second region (102), the second absorption layer (6) being a metallic chromium layer, and the thickness of the second absorption layer (6) being not less than 40 nm.

10. The method for preparing a surface plasma lithography mask according to claim 7, characterized in that, Step S4 includes the following steps: S41. A second photoresist layer (7) is prepared on the first surface (100); the second photoresist layer (7) covers the first region (101), the transition surface (12) and the second region (102). S42. The second photoresist layer (7) is exposed by laser direct writing and developed to form a first groove ring (13) in the area corresponding to the transition surface (12) of the boss (5). S43. A third photoresist layer (8) is prepared on the bottom surface of the groove (4); S44. The first surface (100) is irradiated with ultraviolet light, and the third photoresist layer (8) is exposed using the first groove ring (13). After development, a second groove ring (9) is formed in the area corresponding to the third photoresist layer (8) on the bottom surface of the groove (4). S45. A barrier layer (10) is prepared in the second groove ring (9) of the third photoresist layer (8), and the remaining second photoresist layer (7) and third photoresist layer (8) are removed to complete the mask preparation.

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