Photoresist coating method for large-aperture special-shaped monocrystalline silicon diffraction element

Abstract

The invention discloses a photoresist coating method for a large-aperture special-shaped monocrystalline silicon diffraction element, which solves the problems of small application range, poor coating quality and easy falling of a photoresist layer in the existing photoresist coating method, and specifically comprises the following steps: step 1, screening surface states; step 2, cleaning the surface of the element; step 3, coating a tackifier; step 4, coating a photoresist; and step 5, quality detection. According to the method, the tackifier is firstly coated before the photoresist is coated, and the action mechanism of the tackifier is mainly to replace a hydrophilic Si-HO group carried by an oxide layer on the surface of the monocrystalline silicon substrate, so that the hydrophilicity of the monocrystalline silicon substrate is changed into hydrophobicity, the adhesive force of the monocrystalline silicon substrate and the photoresist is increased, the degumming phenomenon is avoided, the firmness of the photoresist layer is improved, and the service life of the photoresist layer is prolonged.

Description

Technical Field

[0001] The invention relates to a photoresist coating method, in particular to a photoresist coating method for a large-caliber special-shaped single-crystal silicon diffraction element. Background Art

[0002] Single crystal silicon diffractive optical elements are an important type of element in the field of optics. Compared with traditional refractive and reflective elements, the optical focal length of large-aperture single crystal silicon diffractive elements is entirely introduced by the diffraction structure and does not rely on the change in surface curvature. Large-aperture single crystal silicon diffractive elements have the advantages of small size, light weight and low cost, and are widely used in space remote sensing, spectral measurement, optical communication and other fields.

[0003] The photoresist coating method is one of the core processes in the manufacturing process of optical diffraction elements, including the steps of cleaning the diffraction element, photoresist coating, and post-baking. The photoresist is evenly coated on the surface of the large-aperture diffraction element for the subsequent transfer of the exposure pattern.

[0004] The existing photoresist coating method usually adopts the method of spin coating. The coating machine sprays the photoresist on the center of the component surface during low-speed rotation. When the preset value of the photoresist dosage is reached, the nozzle stops spraying the photoresist, and the coating machine drives the component to perform high-speed circular motion. During the high-speed rotation of the component, the photoresist is coated on its surface by centrifugal force. However, due to the large difference in centrifugal force at each point on the circumference, the thickness of the photoresist coating on the component surface is different, which seriously affects the coating quality of the photoresist. At the same time, the existing coating method is only suitable for circular, rectangular and square optical components. For regular hexagonal ones, the existing coating method is difficult to adapt to the use requirements.

[0005] In addition, for single-crystal silicon diffraction elements, they will not react with oxygen to produce silicon oxide under normal conditions. However, when single-crystal silicon is exposed to a humid, high-temperature or highly oxidizing environment for a long time, or is cleaned in a concentrated sulfuric acid and hydrogen peroxide mixture, a native oxide layer about 1nm to 2nm thick will be generated on the surface. This native oxide layer is also called a silicon oxide passivation layer. The groups on the silicon oxide surface exist in two forms, one is a hydrophilic Si-HO group, and the other is a hydrophobic SI-O group. Usually, only under high pressure and high temperature conditions will the surface of silicon oxide produce hydrophobic SI-O groups, while the surface of conventional silicon oxide is generally hydrophilic Si-HO groups. The presence of hydrophilic Si-HO groups will make the adhesion between the photoresist and the element substrate worse, which will cause the photoresist to easily debond. Although controlling the formation of oxide layer is a solution, it is difficult to implement from the perspective of the actual product development process. First, polishing the component substrate is a long and repetitive process. Polishing is carried out in an aqueous solution environment, and it is difficult to avoid the formation of oxide layer. In addition, it is difficult to achieve constant temperature and dry storage environment. Second, cleaning the monocrystalline silicon substrate with a concentrated sulfuric acid and hydrogen peroxide mixture is an effective means of removing surface organic matter. If this cleaning process is not performed, the organic matter on the surface will cause defects in the substrate coating on the component surface.

[0006] Therefore, there is an urgent need for a single crystal silicon diffraction element photoresist coating method with a wide range of applications, high coating quality, and a firm adhesive layer. Summary of the invention

[0007] The purpose of the present invention is to provide a photoresist coating method for a large-caliber special-shaped single-crystal silicon diffraction element, so as to solve the technical problems of the existing coating method, such as small application range, poor coating quality and easy peeling of the adhesive layer.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A method for coating photoresist on a large-caliber special-shaped single-crystal silicon diffraction element is special in that it comprises the following steps:

[0010] Step 1, surface state screening;

[0011] Screening out the components to be coated with glue with qualified surface conditions; the components to be coated with glue are special-shaped flat-plate diffraction components with a diameter D ≥ 300 mm;

[0012] Step 2: Clean the surface of the component;

[0013] The screened components to be coated with glue are placed into a cleaning tool for cleaning;

[0014] Step 3, coating of tackifier;

[0015] The cleaned component to be coated is loaded into the coating tool, fixed and adsorbed on the coating machine, the coating machine applies a tackifier to the surface of the component to be coated, and then the component to be coated with the coating tool is baked for the first time;

[0016] Step 4, photoresist coating;

[0017] After the first baking, the component to be coated with the coating tool is fixed again and adsorbed on the coating machine, and the coating machine applies photoresist to the surface of the adhesion promoter on the component to be coated, and then the component to be coated with the coating tool is baked for the second time;

[0018] Step 5: Quality inspection;

[0019] After the second baking, the photoresist layer quality is inspected for the coated component. If the quality of the layer is unqualified, the process returns to step 2 until the quality of the layer is qualified, thereby completing the photoresist coating method.

[0020] Furthermore, step 3 is specifically as follows: loading the component to be glued after cleaning into the glue coating tool, adsorbing the component to be glued to the corresponding position of the glue coating machine, and then fixing the glue coating tool on the glue coating machine. The dripper of the glue coating machine drips the viscosity enhancer on the surface of the component to be glued in the form of a spiral line. The glue coating machine drives the component to be glued with the glue coating tool to rotate, so that the viscosity enhancer can be evenly distributed on each point on the surface of the component to be glued, and then removes the glue coating tool from the glue coating machine, and bakes the component to be glued with the glue coating tool for the first time.

[0021] Further, in step 3, the glue coating tooling includes an aluminum alloy disc and a plurality of buckles;

[0022] The middle of the aluminum alloy disc is provided with a mounting groove whose shape matches the shape of the component to be coated with glue and has a mounting gap;

[0023] The depth of the mounting groove is less than the thickness of the component to be coated with glue, and is used to mount the component to be coated with glue; a through hole is provided in the middle of the bottom of the mounting groove, and is used for the glue coating machine to adsorb the component to be coated with glue;

[0024] The installation gap width is 2 mm to 3 mm, and the installation gap is filled by a buffer strip;

[0025] The material of the buffer strip is polytetrafluoroethylene;

[0026] The multiple buckles are arranged around the edge of the installation groove, one end of each buckle is connected to the surface of the aluminum alloy disc, and the other end is used to clamp the component to be coated with glue; the material of the buckle is polytetrafluoroethylene.

[0027] Furthermore, in step 3, the rotation speed of the glue coating machine is 1200r / min to 1400r / min, and the rotation time is 0.8min to 1.2min;

[0028] The temperature of the first baking is 90° C. to 100° C., and the baking time is 1 min to 3 min.

[0029] Furthermore, in step 3, the rotation speed of the glue coating machine is 1300 r / min, and the rotation time is 1 min;

[0030] The first baking temperature is 95° C. and the baking time is 2 minutes.

[0031] Furthermore, in step 3, the rate at which the glue coating machine drips the viscosity enhancer is 2 ml / s to 6 ml / s.

[0032] Furthermore, step 4 is specifically as follows: after the first baking, the component to be coated is adsorbed again on the corresponding position of the glue coating machine, and then the glue coating tool is fixed on the glue coating machine. The dripper of the glue coating machine drips the photoresist in the form of a spiral line on the surface of the tackifier on the component to be coated. The glue coating machine drives the component to be coated with the glue coating tool to rotate, so that the photoresist can be evenly distributed on each point on the surface of the component to be coated, and then the glue coating tool is removed from the glue coating machine, and the component to be coated with the glue coating tool is baked for the second time.

[0033] Furthermore, in step 4, the rotation speed of the glue coating machine is 1200r / min to 1400r / min, and the rotation time is 0.8min to 1.2min;

[0034] The second baking temperature is 90° C. to 100° C., and the baking time is 1 min to 3 min.

[0035] Furthermore, in step 3, the rotation speed of the glue coating machine is 1300 r / min, and the rotation time is 1 min;

[0036] The second baking temperature is 95° C. and the baking time is 2 minutes.

[0037] Further, step 2 is specifically to load the selected components to be coated with glue into a cleaning tool, and sequentially clean them through a deionized water tank, an isopropyl alcohol tank, a concentrated sulfuric acid + hydrogen peroxide tank, a deionized water tank, and an isopropyl alcohol steam tank, wherein the cleaning time in each tank is 5 minutes, and the temperature in the isopropyl alcohol steam tank is 75°C to 85°C;

[0038] Step 5 specifically includes removing the glue coating tool from the glue coating machine, removing the glue-coated components from the glue coating tool, and detecting the uniformity of the glue layer thickness on the surface of the glue-coated components by a glue layer thickness tester. If the glue layer thickness at each point on the surface is inconsistent, the glue layer quality is unqualified, then return to step 2 and adjust the rotation speed and / or rotation time of the glue coating machine until the glue layer quality is qualified and the photoresist coating is completed.

[0039] Beneficial effects of the present invention:

[0040] 1. The present invention first applies a tackifier before applying the photoresist. The main mechanism of action of the tackifier is to replace the hydrophilic Si-HO group carried by the oxide layer on the surface of the single crystal silicon substrate, thereby changing the single crystal silicon substrate from hydrophilic to hydrophobic, increasing the adhesion with the photoresist, avoiding debonding, improving the firmness of the adhesive layer, and extending its life.

[0041] 2. The present invention provides a glue coating tool for the special-shaped single-crystal silicon diffraction element. The mounting groove on the glue coating tool can be set according to the shape of the element to be glued. It can be applicable to hexagonal elements to be glued, fan-shaped elements to be glued, and other special-shaped elements, thereby expanding the scope of application of the glue coating method.

[0042] 3. In the present invention, an installation gap is left between the side wall of the installation groove and the side wall of the component to be glued, and a buffer strip is filled in the installation gap. The buffer strip can limit the lateral movement of the component to be glued, and at the same time, the component to be glued is longitudinally limited by a buckle, thereby avoiding the risk of flying flakes caused by insufficient adsorption force in the prior art, that is, the risk of the component to be glued flying out during the rotation of the glue coating machine, and also avoiding the risk of component damage caused by the rigid contact between the component to be glued and the glue coating tooling.

[0043] 4. The present invention provides a glue coating tooling for the special-shaped single-crystal silicon diffraction element, the depth of the mounting groove of which is less than the thickness of the element to be coated with glue, which can avoid the accumulation of photoresist at the edge of the element to be coated with glue and avoid affecting the uniformity of the entire mirror adhesive layer.

[0044] 5. In the photoresist coating method provided by the present invention, whether it is a drop of thickener or photoresist, it is coated in the form of a spiral line on the surface of the component to be coated, and then rotated. This can avoid the difference in the thickness of the thickener or photoresist coating caused by the difference in centrifugal force at each point on the large-diameter circle, greatly improve the uniformity of the photoresist coating on the surface of the component to be coated, and thus improve the quality of the photoresist layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a flow chart of an embodiment of a method for coating photoresist on a large-caliber special-shaped single-crystal silicon diffraction element according to the present invention;

[0046] Figure 2 It is a top view of a gluing tooling installed with a component to be glued in an embodiment of the present invention.

[0047] Figure Number:

[0048] 1-component to be coated with glue, 2-coating tooling, 3-installation gap, 4-adsorption point, 5-spiral line. DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The embodiment of the present invention provides a method for coating photoresist on a large-diameter special-shaped single-crystal silicon diffraction element, such as Figure 1 As shown, the photoresist coating method comprises the following steps:

[0051] Step 1, surface state screening process;

[0052] Screening out a component 1 to be coated with glue with a qualified surface state, wherein the component 1 to be coated with glue is a special-shaped flat-plate diffraction component with a diameter D≥300 mm, that is, a large-diameter special-shaped single-crystal silicon diffraction component;

[0053] The surface state screening process can visually check whether there are large particles attached to the surface of the component 1 to be coated with glue, whether there are scratches, whether there are broken edges, whether there is pollution, etc. under a strong light to determine whether the component 1 to be coated with glue can enter the next processing process;

[0054] Step 2: Component surface cleaning process;

[0055] The selected components to be coated with glue 1 are loaded into the cleaning tool, and are cleaned in turn through a deionized water tank, an isopropyl alcohol tank, a concentrated sulfuric acid + hydrogen peroxide tank, a deionized water tank, and an isopropyl alcohol steam tank. The cleaning time in each tank is 5 minutes, and the temperature in the isopropyl alcohol steam tank is 75°C to 85°C.

[0056] The cleaning tooling is a tooling for ultrasonic cleaning equipment, which is usually suitable for cleaning square or round wafers. Rectangular tooling can generally be used for special-shaped components. For regular hexagonal components, the base and left and right vertices of the regular hexagonal components can be fixed to the cleaning tooling by buckles, and the buckle position can be located at the midpoint of each side of the hexagon.

[0057] The purpose of the component surface cleaning process is to remove the water film attached to the component to be coated, improve the adhesion of the photoresist to the surface of the component to be coated, and further remove the tiny particles and some organic matter attached to the component to be coated; in the cleaning process, the cleaning tool is installed on the transmission mechanism, and passes through the deionized water tank, isopropyl alcohol tank, concentrated sulfuric acid + hydrogen peroxide, deionized water tank, isopropyl alcohol steam tank in sequence. Each tank body has an ultrasonic function, and the cleaning time of each tank body can be 5 minutes. The temperature of the isopropyl alcohol steam tank is 75℃~85℃, which is about 80℃ in this embodiment. The transmission mechanism is a mechanism that drives the cleaning tool to move in each cleaning tank, similar to a gantry crane, and puts the cleaning tool into the cleaning tank. After the cleaning time is met, the cleaning tool is lifted and moved horizontally to the next cleaning tank, and then the cleaning tool is put into the cleaning tank. After the cleaning time is met, the cleaning tool is lifted again, and so on, passing through the cleaning tanks one by one.

[0058] Step 3, tackifier coating process;

[0059] The cleaned component 1 to be coated with glue is loaded into the glue coating tool 2, the component 1 to be coated with glue is adsorbed on the corresponding position of the glue coating machine, and then the glue coating tool 2 is fixed on the glue coating machine. The dripper of the glue coating machine drips the viscosity enhancer on the surface of the component 1 to be coated with glue in the form of a spiral line 5. The glue coating machine drives the glue coating tool 2 to rotate. The rotation speed range of the glue coating machine is 1200r / min~1400r / min, the rotation time range is 0.8min~1.2min, and the rate range of the dripper of the glue coating machine dripping the viscosity enhancer is 2ml / s~6ml / s; in this embodiment, the rotation speed of the glue coating machine is 1300r / mi n, the rotation time is 1 min; the glue coating machine drives the glue coating tool 2 to rotate so that the tackifier can be evenly distributed on each point on the surface of the component 1 to be coated with glue, and then the glue coating tool 2 is removed from the glue coating machine, and the component 1 to be coated with the glue coating tool 2 is baked for the first time. The temperature range of the first baking is 90°C to 100°C, and the baking time range is 1min to 3min. In this embodiment, the temperature of the first baking is 95°C, and the baking time is 2min. The purpose of the first baking is to remove the solvent in the tackifier and form a base film with strong adhesion to the component 1 to be coated and the photoresist layer.

[0060] In the tackifier coating process and the subsequent photoresist coating process, the component 1 to be coated is fixed in the corresponding position of the coating machine by adsorption at the center of the back. However, for large-aperture flat-plate diffraction elements, the center adsorption area accounts for a small proportion and the adsorption force is insufficient. There is a risk of flying flakes in the component 1 to be coated during the coating process. Therefore, this embodiment designs a special coating tool to solve the above problem.

[0061] like Figure 2As shown, the outer envelope size of the glue coating tool 2 is slightly larger than the size of the component 1 to be coated with glue, and the glue coating tool 2 includes an aluminum alloy disc and a plurality of buckles; a mounting groove whose shape matches the shape of the component 1 to be coated with glue and is provided with a mounting gap 3 is provided in the middle of the aluminum alloy disc; the depth of the mounting groove is less than the thickness of the component 1 to be coated with glue, and is used to install the component 1 to be coated with glue; a through hole is provided in the middle of the bottom of the mounting groove, which is used to adsorb the adsorption point 4 on the back of the component 1 to be coated with glue to the corresponding position of the glue coating machine; the glue coating machine adsorbs the back of the component 1 to be coated with glue by vacuuming; the mounting gap 3 is 2mm to 3mm wide, and the mounting gap 3 is filled with a buffer strip; the buffer strip is made of polytetrafluoroethylene, which plays a buffering role to avoid damage to the component during high-speed glue coating caused by rigid contact between the tool and the component; a plurality of buckles are arranged around the edge of the mounting groove, one end of each buckle is connected to the surface of the aluminum alloy disc, and the other end is used to clamp the component 1 to be coated with glue; the buckle can be made of polytetrafluoroethylene to avoid scratching the surface of the component 1 to be coated with glue.

[0062] Step 4, photoresist coating process;

[0063] After the first baking, the component 1 to be coated with glue is adsorbed again on the corresponding position of the glue coating machine, and then the glue coating tool 2 is fixed on the glue coating machine. The dripper of the glue coating machine drips the photoresist in the form of a spiral line 5 on the surface of the tackifier on the component 1 to be coated with glue. The glue coating machine drives the glue coating tool 2 to rotate. The rotation speed range of the glue coating machine is 1200r / min~1400r / min, and the rotation time range is 0.8min~1.2min; in this embodiment, the rotation speed of the glue coating machine is 1300r / min, and the rotation time is 1min; the glue coating machine rotates so that the photoresist can be evenly distributed on each point on the surface of the component 1 to be coated with glue, and then the glue coating tool 2 is removed from the glue coating machine, and the component 1 to be coated with the glue coating tool 2 is baked for the second time. The temperature range of the second baking is 90℃~100℃, and the baking time range is 1min~3min; in this embodiment, the temperature of the second baking is 95℃, and the baking time is 2min. The purpose of the second baking is to remove excess solvent in the glue layer so that the glue layer adheres more firmly to the primary mirror substrate.

[0064] Step 5: Quality inspection process;

[0065] Remove the glue coating tool 2 from the glue coating machine, remove the glue-coated component from the glue coating tool 2, and use a glue layer thickness tester to detect the uniformity of the glue layer thickness on the surface of the glue-coated component. If the glue layer thickness at each point on the surface is inconsistent, the glue layer quality is unqualified, then return to step 2 and adjust the rotation speed and / or rotation time of the glue coating machine until the glue layer quality is qualified, and the photoresist coating method is completed.

[0066] The present embodiment provides a method for photoresist coating of large-aperture special-shaped single-crystal silicon diffraction elements, which can meet the photoresist coating processing requirements of regular hexagonal, fan-shaped and other special-shaped single-crystal silicon diffraction elements, and at the same time, can solve the problem of photoresist uniformity of large-aperture special-shaped flat-plate single-crystal silicon diffraction elements.

[0067] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for coating photoresist on a large-diameter, special-shaped single-crystal silicon diffraction element, characterized in that: The following steps are involved: Step 1, surface state screening; Screening out the components to be coated with glue with qualified surface conditions; the components to be coated with glue are special-shaped flat-plate diffraction components with a diameter D ≥ 300 mm; Step 2: Clean the surface of the component; The screened components to be coated with glue are placed into a cleaning tool for cleaning; Step 3, coating of tackifier; The cleaned component to be coated is loaded into the coating tool, fixed and adsorbed on the coating machine, the coating machine applies a tackifier to the surface of the component to be coated, and then the component to be coated with the coating tool is baked for the first time; Step 4, photoresist coating; After the first baking, the component to be coated with the coating tool is fixed again and adsorbed on the coating machine, and the coating machine applies photoresist to the surface of the adhesion promoter on the component to be coated, and then the component to be coated with the coating tool is baked for the second time; Step 5: Quality inspection; After the second baking, the photoresist layer quality is inspected for the coated component. If the quality of the layer is unqualified, the process returns to step 2 until the quality of the layer is qualified, thereby completing the photoresist coating method.

2. The photoresist coating method for large-diameter special-shaped single-crystal silicon diffraction element according to claim 1 is characterized in that: Step 3 specifically includes loading the cleaned component to be glued into the glue coating tool, adsorbing the component to be glued to the corresponding position of the glue coating machine, and then fixing the glue coating tool on the glue coating machine. The dripper of the glue coating machine drips the viscosity enhancer on the surface of the component to be glued in the form of a spiral line. The glue coating machine drives the component to be glued with the glue coating tool to rotate, so that the viscosity enhancer can be evenly distributed on each point on the surface of the component to be glued. Then, the glue coating tool is removed from the glue coating machine, and the component to be glued with the glue coating tool is baked for the first time.

3. The photoresist coating method for large-diameter special-shaped single-crystal silicon diffraction element according to claim 2 is characterized in that: In step 3, the glue coating tool includes an aluminum alloy disc and a plurality of buckles; The middle of the aluminum alloy disc is provided with an installation groove whose shape matches the shape of the component to be coated with glue and has an installation gap; The depth of the mounting groove is less than the thickness of the component to be coated with glue, and is used to mount the component to be coated with glue; a through hole is provided in the middle of the bottom of the mounting groove, and is used for the glue coating machine to adsorb the component to be coated with glue; The installation gap width is 2 mm to 3 mm, and the installation gap is filled by a buffer strip; The material of the buffer strip is polytetrafluoroethylene; The multiple buckles are arranged around the edge of the installation groove, one end of each buckle is connected to the surface of the aluminum alloy disc, and the other end is used to clamp the component to be coated with glue; the material of the buckle is polytetrafluoroethylene.

4. The photoresist coating method for large-diameter special-shaped single-crystal silicon diffraction element according to claim 3 is characterized in that: In step 3, the rotation speed of the glue coating machine is 1200r / min to 1400r / min, and the rotation time is 0.8min to 1.2min; The temperature of the first baking is 90° C. to 100° C., and the baking time is 1 min to 3 min.

5. The method for coating photoresist on a large-diameter special-shaped single-crystal silicon diffraction element according to claim 4, characterized in that: In step 3, the rotation speed of the glue coating machine is 1300r / min, and the rotation time is 1min; The first baking temperature is 95° C. and the baking time is 2 minutes.

6. The photoresist coating method for large-diameter special-shaped single-crystal silicon diffraction element according to claim 4, characterized in that: In step 3, the rate at which the glue coating machine drips the viscosity enhancer is 2 ml / s to 6 ml / s.

7. The method for coating photoresist on a large-diameter, special-shaped single-crystal silicon diffraction element according to any one of claims 1 to 6, characterized in that: Specifically, step 4 is as follows: after the first baking, the component to be coated is adsorbed again on the corresponding position of the glue coating machine, and then the glue coating tool is fixed on the glue coating machine. The dripper of the glue coating machine drips the photoresist in the form of a spiral line on the surface of the tackifier on the component to be coated. The glue coating machine drives the component to be coated with the glue coating tool to rotate, so that the photoresist can be evenly distributed on each point on the surface of the component to be coated. Then the glue coating tool is removed from the glue coating machine, and the component to be coated with the glue coating tool is baked for the second time.

8. The method for coating photoresist on a large-diameter, special-shaped single-crystal silicon diffraction element according to claim 7, characterized in that: In step 4, the rotation speed of the glue coating machine is 1200r / min to 1400r / min, and the rotation time is 0.8min to 1.2min; The second baking temperature is 90° C. to 100° C., and the baking time is 1 min to 3 min.

9. The method for coating photoresist on a large-diameter special-shaped single-crystal silicon diffraction element according to claim 8, characterized in that: In step 3, the rotation speed of the glue coating machine is 1300r / min, and the rotation time is 1min; The second baking temperature is 95° C. and the baking time is 2 minutes.

10. The method for coating photoresist on a large-diameter, special-shaped single-crystal silicon diffraction element according to claim 9, characterized in that: Step 2 is specifically to load the selected components to be coated with glue into the cleaning tool, and sequentially clean them through a deionized water tank, an isopropyl alcohol tank, a concentrated sulfuric acid + hydrogen peroxide tank, a deionized water tank, and an isopropyl alcohol steam tank. The cleaning time in each tank is 5 minutes, and the temperature in the isopropyl alcohol steam tank is 75°C to 85°C. Step 5 specifically includes removing the glue coating tool from the glue coating machine, removing the glue-coated components from the glue coating tool, and detecting the uniformity of the glue layer thickness on the surface of the glue-coated components by a glue layer thickness tester. If the glue layer thickness at each point on the surface is inconsistent, the glue layer quality is unqualified, then return to step 2 and adjust the rotation speed and / or rotation time of the glue coating machine until the glue layer quality is qualified and the photoresist coating is completed.

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