A method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist

Abstract

This invention relates to the field of electromagnetic shielding materials technology, and discloses a method for fabricating a metal mesh electromagnetic shielding optical window based on a single-layer positive photoresist. This invention proposes a method to form an undercut photoresist pattern on the surface of the optical window through two exposures in different directions, thereby obtaining the metal mesh electromagnetic shielding optical window. In the two exposures, the first exposure is a back-side generalized exposure, and the generalized exposure area acts as a sacrificial layer, avoiding multiple photoresist coating and baking processes, greatly simplifying the process. The method for fabricating a metal mesh electromagnetic shielding optical window based on a single-layer positive photoresist provided by this invention has advantages such as simple operation, high fabrication efficiency and high yield, and avoids the problem of mutual interference between reagents of various photoresists. The resulting product has excellent electromagnetic shielding performance and optical transmittance.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic shielding optical materials, and specifically discloses a method for preparing a metal grid electromagnetic shielding optical window based on a single-layer positive photoresist. Background Art

[0002] In modern society, optical windows face extremely complex spatial electromagnetic environments during use, so it is necessary to ensure the electromagnetic shielding effect of optical windows. As one of the effective methods to achieve electromagnetic shielding of optical windows, metal grid electromagnetic shielding technology has received extensive attention and research.

[0003] Positive photoresist has excellent photosensitivity and resolution and is widely used in semiconductor lithography processes. Compared with negative photoresist, positive photoresist is more suitable for the stripping process of metal patterns. At present, the mainstream preparation method for preparing metal grids is the stripping route, that is, by coating a layer of positive photoresist on the surface of the optical window, and then forming the pattern of the photoresist by photolithography, and selectively stripping after metal plating to form a metal grid. The main problem of this technical route is that the stripping is not thorough. Although the thickness of the photoresist is much greater than the thickness of the metal coating, the divergence angle of the metal coating and the morphological defects of the exposure can easily lead to metal adhesion between the side wall of the photoresist and the bottom of the line. It is reported that a multi-layer glue process has been used to prepare the undercut structure of the positive photoresist to optimize the stripping. Although this technology can achieve relatively easy metal selective removal, it is not only costly, but also requires multiple coatings and baking, and different photoresist solvents have mutual influences, and the process is relatively complicated. Therefore, it is of certain significance to use a single layer of positive photoresist to prepare the undercut structure, simplify the manufacturing process, and reduce the manufacturing cost. Summary of the invention

[0004] In view of the conventional single-layer positive photoresist-based metal grid electromagnetic shielding optical window preparation in the prior art, there are peeling difficulties including incomplete peeling or broken wires; and although the metal grid electromagnetic shielding optical window prepared by multi-layer photoresist can solve the peeling difficulties, the process is complicated, time-consuming and costly. In view of positive photoresist, the present invention provides a method for preparing an undercut structure by a single-layer photoresist, which is simple to operate and efficient.

[0005] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0006] In the first aspect, the present invention provides a method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, and the preparation process flow chart thereof is as follows: Figure 1 As shown, step 1, coating a layer of positive photoresist on the pre-treated optical window surface, and baking to obtain an optical window coated with positive photoresist;

[0007] Step 2, performing back-flooding exposure on the optical window coated with the positive photoresist to obtain a back-flooded optical window coated with the positive photoresist;

[0008] Step 3: Place the optical window coated with positive photoresist and exposed from the back side with the front side facing upward, place the mask, and expose from the front side to obtain an optical window coated with positive photoresist and exposed from the front side; wherein the energy of the front exposure is the energy E that can just expose the positive photoresist through. 正 , the data is obtained from experimental tests;

[0009] Step 4, developing the optical window coated with the positive photoresist and exposed on the front side to obtain an optical window with an undercut structure;

[0010] Step 5: Plating a chrome layer and a copper layer in sequence on the surface of the optical window with the undercut structure, peeling off the glue, and obtaining a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist;

[0011] The energy calculation formula of the back side flood exposure is shown in Formula 1:

[0012] Formula 1

[0013] In formula 1:

[0014] E 背 The energy of back flooding exposure, in mJ / cm 2 ; E 正 is the energy that can just expose the positive photoresist, obtained from experimental tests; T is the optical transmittance of the optical window coated with positive photoresist to the exposure light source, which can be selected from 10% to 100%, preferably 10% to 30%; p is the proportional coefficient related to the exposure depth, which is 0.25 to 0.5.

[0015] In the process of preparing metal mesh electromagnetic shielding optical windows, the undercut structure can effectively avoid the deposition of metal photoresist on the side, thereby promoting stripping; while the photoresist pattern without undercut structure is very likely to have problems of incomplete stripping or broken wires after metal coating, which in turn affects the performance of the optical window. Figure 2 In the prior art, it is impossible to prepare a relatively obvious undercut structure by using a single layer of photoresist, while the preparation by using multiple layers of photoresist is complicated and inefficient, and there is also the problem of interference between reagents of multiple photoresists.

[0016] For positive photoresist, the present invention proposes a method for preparing an undercut structure by applying a double exposure. The first exposure is a back flood exposure, and the flood exposure area is used as a sacrificial layer to avoid the process of multiple photoresist coating and baking, which greatly simplifies the process. The method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist provided by the present invention has the advantages of simple operation, high preparation efficiency and yield, and there is no problem of interference between reagents of multiple photoresists.

[0017] Preferably, step 1 specifically comprises: coating a layer of positive photoresist on the clean surface of the optical window, and baking in an environment of 80° C. to 110° C. for 10 min to 20 min to obtain the optical window coated with the positive photoresist;

[0018] Wherein, the thickness of the coated positive photoresist is 5um~10um.

[0019] The preparation process of the clean optical window includes: ultrasonically cleaning the optical window to be treated with acetone and alcohol reagent for 10 minutes to 20 minutes respectively, and baking at 100° C. to 150° C. for 30 minutes to 40 minutes to obtain the clean optical window.

[0020] Preferably, the positive photoresist includes but is not limited to AZ4620, AZ4562 or AZ1505.

[0021] The wavelength of the back flood exposure light source is 350nm~450nm, and the exposure energy is 100mJ / cm 2 ~200mJ / cm 2 .

[0022] Preferably, the front exposure mode includes vacuum contact exposure;

[0023] The vacuum contact exposure has a wavelength of 350nm~450nm and an exposure energy of 50mJ / cm 2 ~150mJ / cm 2 , the adsorption pressure is -28KPa~-32KPa.

[0024] Preferably, the developing solution of the developing treatment includes at least one of potassium hydroxide solution, sodium hydroxide solution or TMAH developing solution, and the developing time is 1 min to 3 min.

[0025] Preferably, the thickness of the chromium layer is 10 nm to 20 nm, and the thickness of the copper layer is 100 nm to 500 nm.

[0026] Preferably, during the stripping and debonding, an N-methylpyrrolidone aqueous solution with a mass concentration of 15% to 35% is used.

[0027] In a second aspect, the present invention provides a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, and the optical window is prepared by the above-mentioned method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist.

[0028] The metal grid electromagnetic shielding optical window based on a single-layer positive photoresist provided by the present invention has a simple preparation process and has excellent electromagnetic shielding performance and optical transmittance performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 The present invention is a process flow chart of preparing a metal grid electromagnetic shielding optical window based on a single-layer positive photoresist;

[0031] Figure 2 FIG. 1 is a schematic diagram comparing the stripping process of the photoresist pattern containing the undercut structure in the present invention and the undercut structure in the present invention. Figure 2 a is a schematic diagram of the stripping process of a photoresist pattern without an undercut structure. Figure 2 b is a schematic diagram of the stripping process of a photoresist pattern containing an undercut structure. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0033] In order to better illustrate the embodiments of the present invention, further examples are given below.

[0034] Example 1

[0035] This embodiment provides a method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist. The preparation process flow chart is as follows: Figure 1 As shown, the specific steps include:

[0036] Step 1: ultrasonically clean the optical window to be processed using acetone and alcohol reagent for 20 minutes respectively, and bake it in an oven at 150°C for 30 minutes to obtain a clean optical window;

[0037] A layer of AZ4620 positive photoresist is coated on the clean optical window surface, the thickness of the photoresist is 10 μm, and the optical window coated with positive photoresist is obtained by baking in an oven at 80° C. for 10 min.

[0038] Step 2: Perform back flood exposure, select LED light as exposure light source, set the light source wavelength to 405nm, and the exposure energy to 200mJ / cm 2 , flood-exposing the optical window coated with the positive photoresist to obtain an optical window coated with the positive photoresist with a back side flood-exposed;

[0039] The energy calculation formula of the back side flood exposure is shown in Formula 1:

[0040] Formula 1

[0041] Among them, p is 0.4, and it is determined that E 正 150mJ / cm 2 , T is 30%;

[0042] Step 3: Place the optical window coated with positive photoresist facing up, place the mask, select the exposure light source as LED light, set the light source wavelength to 405nm, and the exposure energy to 150mJ / cm 2 , the adsorption pressure is -30KPa, and vacuum contact exposure is performed to obtain an optical window coated with positive photoresist with positive exposure;

[0043] Step 4, developing the optical window coated with the positive photoresist and exposed on the front side in a TMAH 2.38% developer for 3 minutes to obtain an optical window with an undercut structure photoresist pattern;

[0044] Step 5: a chromium layer with a thickness of 10 nm and a copper layer with a thickness of 500 nm are plated in sequence on the surface of the optical window with the undercut structure to obtain a metal grid sample;

[0045] Use 15% N-methylpyrrolidone aqueous solution to remove glue; in this process, it is found that the stripping and degumming are smooth, and there is no phenomenon of incomplete stripping or broken wires;

[0046] The metal grid sample after stripping and debonding was cleaned with alcohol ultrasonic cleaning for 10 minutes to obtain a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, which was recorded as optical window I.

[0047] Example 2

[0048] This embodiment provides a method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, which specifically includes the following steps:

[0049] Step 1: Use acetone and alcohol reagent to ultrasonically clean the optical window to be treated for 10 minutes respectively, and bake it in an oven at 100°C for 40 minutes to obtain a clean optical window;

[0050] A layer of AZ4562 positive photoresist is coated on the clean optical window surface, the thickness of the photoresist is 5 μm, and the optical window coated with positive photoresist is obtained by baking it in an oven at 100° C. for 20 minutes;

[0051] Step 2: Perform back flood exposure, select LED light as exposure light source, set the light source wavelength to 365nm, and the exposure energy to 125mJ / cm 2 , flood-exposing the optical window coated with the positive photoresist to obtain an optical window coated with the positive photoresist with a back side flood-exposed;

[0052] The energy calculation formula of the back side flood exposure is shown in Formula 1:

[0053] Formula 1

[0054] Among them, p is 0.25, and the measured E 正 100mJ / cm 2 , T is 20%;

[0055] Step 3: Place the optical window coated with positive photoresist facing up, place the mask, select the exposure light source as LED light, set the light source wavelength to 365nm, and the exposure energy to 100mJ / cm 2 , the adsorption pressure is -32KPa, and vacuum contact exposure is performed to obtain an optical window coated with positive photoresist with positive exposure;

[0056] Step 4, developing the optical window coated with the positive photoresist and exposed on the front side in a potassium hydroxide solution with a mass concentration of 1.5% for 1 minute to obtain an optical window with an undercut structure;

[0057] Step 5: a chromium layer with a thickness of 20 nm and a copper layer with a thickness of 300 nm are plated in sequence on the surface of the optical window with the undercut structure to obtain a metal grid sample;

[0058] Use 20% N-methylpyrrolidone aqueous solution to remove glue; in this process, it is found that the stripping and degumming are smooth, and there is no phenomenon of incomplete stripping or broken wires;

[0059] The metal grid sample after stripping and debonding was cleaned with alcohol ultrasonic cleaning for 10 minutes to obtain a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, which was recorded as optical window II.

[0060] Example 3

[0061] This embodiment provides a method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, which specifically includes the following steps:

[0062] Step 1: Use acetone and alcohol reagent to ultrasonically clean the optical window for 15 minutes respectively, and bake it in an oven at 120°C for 35 minutes to obtain a clean optical window;

[0063] A layer of AZ1505 positive photoresist is coated on the clean optical window surface, the thickness of the photoresist is 8 μm, and the optical window coated with positive photoresist is obtained by baking in an oven at 110° C. for 15 minutes;

[0064] Step 2: Perform back flood exposure, select the exposure light source as a mercury lamp, set the light source wavelength to 436nm, and the exposure energy to 150mJ / cm 2 , flood-exposing the optical window coated with the positive photoresist to obtain an optical window coated with the positive photoresist with a back side flood-exposed;

[0065] The energy calculation formula of the back side flood exposure is shown in Formula 1:

[0066] Formula 1

[0067] Among them, p is 0.3, and the measured E 正 50mJ / cm 2 , T is 10%;

[0068] Step 3: Place the optical window coated with positive photoresist facing up, place the mask, select the exposure light source as a mercury lamp, set the light source wavelength to 436nm, and the exposure energy to 50mJ / cm 2 , the adsorption pressure is -28KPa, and vacuum contact exposure is performed to obtain an optical window coated with positive photoresist with positive exposure;

[0069] Step 4, developing the optical window coated with the positive photoresist and exposed on the front side in a sodium hydroxide solution with a mass concentration of 1.5% for 2 minutes to obtain an optical window with an undercut structure;

[0070] Step 5: a chromium layer with a thickness of 15 nm and a copper layer with a thickness of 100 nm are plated in sequence on the surface of the optical window with the undercut structure to obtain a metal grid sample;

[0071] The adhesive was removed by using an aqueous solution of N-methylpyrrolidone with a mass concentration of 35%. During this process, it was found that the adhesive was removed smoothly without incomplete removal or wire breakage.

[0072] The metal grid sample after stripping and debonding was cleaned with alcohol ultrasonic cleaning for 10 minutes to obtain a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, which was recorded as optical window III.

[0073] Comparative Example 1

[0074] This comparative example provides a method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, which specifically comprises the following steps:

[0075] Step 1: ultrasonically clean the optical window to be processed using acetone and alcohol reagent for 20 minutes respectively, and bake it in an oven at 150°C for 30 minutes to obtain a clean optical window;

[0076] A layer of AZ4620 positive photoresist is coated on the clean optical window surface, the thickness of the photoresist is 10 μm, and the optical window coated with positive photoresist is obtained by baking in an oven at 80° C. for 10 min.

[0077] Step 2: Place the optical window coated with positive photoresist facing up, place the mask, select the exposure light source as LED light, set the light source wavelength to 405nm, and the exposure energy to 120mJ / cm 2 , the adsorption pressure is -30KPa, and after vacuum contact exposure, an optical window coated with positive photoresist with positive exposure is obtained;

[0078] Step 3, developing the optical window coated with the positive photoresist and exposed on the front side in a TMAH 2.38% developer for 3 minutes, and obtaining an optical window without an undercut structure after development;

[0079] Step 4, a chromium layer with a thickness of 10 nm and a copper layer with a thickness of 500 nm are plated on the surface in sequence to obtain a metal grid sample;

[0080] Using a 15% mass concentration of N-methylpyrrolidone aqueous solution to remove the adhesive, it was found that the conventional single-layer adhesive did not form an undercut structure, and the adhesive was not completely removed during the stripping process;

[0081] The metal grid optical window sample after debonding was cleaned ultrasonically with alcohol for 10 minutes, and the obtained product was recorded as optical window pair I.

[0082] The schematic diagram of the stripping process comparison of photoresist patterns with or without undercut structures is as follows Figure 2 As shown, Figure 2 a is a schematic diagram of the stripping process of a photoresist pattern without an undercut structure. Figure 2b is a schematic diagram of the stripping process of a photoresist pattern containing an undercut structure. The so-called undercut structure is a structure formed on the photoresist surface after exposure and development, which is wide at the bottom and narrow at the top. In this way, metal deposition will not occur on the side of the photoresist during metal coating, and stripping is relatively simple. In the process according to this comparative example, the undercut structure is formed, resulting in incomplete stripping, which in turn will lead to metal residues, which is likely to affect the performance of the resulting optical window.

[0083] Comparative Example 2

[0084] This comparative example provides a method for preparing a metal grid electromagnetic shielding optical window based on a double-layer glue, which specifically includes the following steps:

[0085] Step 1: ultrasonically clean the optical window to be processed using acetone and alcohol reagent for 20 minutes respectively, and bake it in an oven at 150°C for 30 minutes to obtain a clean optical window;

[0086] A layer of PGMI photoresist as a sacrificial layer is coated on the surface of the clean optical window, the thickness of the photoresist is 1 μm, and the photoresist is placed in an oven and baked at 100° C. for 1 min to remove the solvent, thereby obtaining an optical window coated with a sacrificial layer;

[0087] Step 2: The optical window coated with the sacrificial layer is further coated with AZ4620 positive photoresist with a thickness of 10 μm, and is placed in an oven and baked at 80° C. for 10 min to obtain an optical window coated with a sacrificial layer + positive photoresist;

[0088] Step 3: Place the optical window coated with sacrificial layer + positive photoresist facing up, place the mask, perform vacuum contact exposure, select the exposure light source as LED light, set the light source wavelength to 405nm, and the exposure energy to 120mJ / cm 2 , the adsorption pressure is -30KPa, and after exposure, an optical window with a positive-exposed sacrificial layer + positive photoresist is obtained;

[0089] Step 4: Develop the optical window coated with the sacrificial layer + positive photoresist exposed on the front side in TMAH 2.38% developer for 3 minutes. Since a double-layer photoresist is used to form an undercut structure, an optical window with an undercut structure is obtained.

[0090] Step 5: a chromium layer with a thickness of 10 nm and a copper layer with a thickness of 500 nm are plated in sequence on the surface of the optical window with the undercut structure to obtain a metal grid sample;

[0091] Using 15% N-methylpyrrolidone aqueous solution for stripping and 5% sodium hydroxide solution for degumming, it was found that the surface metal and surface photoresist could be removed smoothly.

[0092] The metal grid sample was ultrasonically cleaned with alcohol for 10 minutes to obtain a metal grid electromagnetic shielding optical window prepared with a double-layer photoresist, which was recorded as optical window pair II.

[0093] Comparative Example 3

[0094] This comparative example provides a method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist. The preparation method is basically the same as that of Example 1, except that the back flood exposure energy is increased from 200 mJ / cm 2 Replaced with 300mJ / cm 2 (ie, p in Formula 1 is 0.6), the remaining steps and parameters are the same as those in Example 1, and the final product is recorded as optical window pair III. During the preparation process, it was found that no obvious undercut structure could be formed in step 4, resulting in incomplete peeling.

[0095] Comparative Example 4

[0096] This comparative example provides a method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist. The preparation method is basically the same as that of Example 1, except that the back flood exposure energy is increased from 200 mJ / cm 2 Replaced with 60mJ / cm 2 (ie, the transmittance is not divided in Formula 1), the remaining steps and parameters are the same as those in Example 1, and the final product is recorded as optical window pair IV. During the preparation process, it was found that no obvious undercut structure could be formed in step IV, resulting in incomplete peeling.

[0097] Effect example

[0098] The present invention conducts a yield test on the metal grid electromagnetic shielding optical windows obtained in Examples 1-3 and Comparative Examples 1-4 (1000 pieces), uses a Fourier transform infrared spectrometer to test the optical transmittance, and conducts an electromagnetic shielding performance test according to the GJB 8820-2015 standard. The specific results are shown in Table 1.

[0099] Table 1 Performance of optical windows made by different preparation processes

[0100]

[0101] It can be seen from the data in Table 1 that the electromagnetic shielding optical windows based on a single layer of metal mesh electromagnetic shielding prepared in Examples 1 to 3 of the present invention have excellent electromagnetic shielding performance and optical transmittance, meet the electromagnetic shielding performance while having a high transmittance, meet the product requirements of the mesh window, and can achieve an effect similar to that of the metal mesh electromagnetic shielding optical window prepared based on a double layer of photoresist in Comparative Example 2. However, the preparation process provided by Examples 1 to 3 of the present invention is simpler, the preparation efficiency and yield are higher, and there will be no problem of interference between reagents of multiple photoresists.

[0102] Comparative Example 1 is a metal mesh electromagnetic shielding optical window prepared using a single layer of glue in the prior art. Since a relatively obvious bottom cut structure cannot be formed during the preparation process, the peeling is not thorough when removing the glue, resulting in metal residue, which in turn affects the performance of the optical window, resulting in poor electromagnetic shielding performance and optical transmittance performance.

[0103] Comparative Examples 3 and 4 are to prepare metal grid electromagnetic shielding optical windows after adjusting the energy of back flooding exposure on the basis of Example 1. It is found that the undercut structure formed by too high back flooding exposure energy is easily destroyed, resulting in the upper layer of photoresist falling off, and the photoresist side wall adhesion after coating, which is difficult to peel off; the undercut structure formed by too low back flooding exposure energy is too short, and the undercut structure can be covered after the metal film layer is plated, forming metal adhesion on the side wall of the photoresist, which is difficult to peel off. This shows that the back flooding exposure energy plays an important role in the formation of the photoresist undercut structure, and needs to be precisely controlled to obtain products with excellent electromagnetic shielding performance and optical transmittance.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, characterized in that: The preparation method comprises the following steps: Step 1, coating a layer of positive photoresist on the clean surface of the optical window, and baking to obtain an optical window coated with the positive photoresist; Step 2, performing back-flooding exposure on the optical window coated with the positive photoresist to obtain a back-flooded optical window coated with the positive photoresist; Step 3, placing the optical window coated with positive photoresist and back-exposed with the front side facing upward, placing the mask, and exposing the front side to obtain an optical window coated with positive photoresist and front-exposed; wherein the energy of the front exposure is the energy that can just expose the positive photoresist through; Step 4, developing the optical window coated with the positive photoresist and exposed on the front side to obtain an optical window with an undercut structure; Step 5: plating a metal layer on the surface of the optical window with the undercut structure, peeling off the glue, and obtaining a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist; The energy of the back flood exposure in step 2 is ; E 背 The energy of back flooding exposure, in mJ / cm 2 ; E 正 is the energy that can just expose the positive photoresist; T is the optical transmittance of the optical window coated with the positive photoresist to the exposure light source; p is the proportional coefficient related to the exposure depth, which is 0.25~0.

5.

2. The method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist according to claim 1, characterized in that: In step 1, the coating thickness of the positive photoresist is 5um to 10um; and / or In step 1, the baking temperature is 80° C. to 110° C., and the baking time is 10 min to 20 min.

3. The method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist according to claim 1, characterized in that: The positive photoresist includes any one of AZ4620, AZ4562 or AZ1505.

4. The method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist according to claim 1, characterized in that: The back flood exposure light source wavelength is 350nm~450nm, and the exposure energy is 100mJ / cm 2 ~200mJ / cm 2 .

5. The method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist according to claim 1, characterized in that: The front exposure mode includes vacuum contact exposure; The light source wavelength of the vacuum contact exposure is 350nm~450nm, and the exposure energy is 50mJ / cm 2 ~150mJ / cm 2 , the adsorption pressure is -28KPa~-32KPa.

6. The method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist according to claim 1, characterized in that: The developing solution of the developing treatment includes at least one of potassium hydroxide solution, sodium hydroxide solution or TMAH developing solution, and the developing time is 1 min to 3 min.

7. The method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist according to claim 1, characterized in that: From bottom to top, the metal layer includes a chromium layer and a copper layer, the thickness of the chromium layer is 10nm-20nm, and the thickness of the copper layer is 100nm-500nm.

8. The method for preparing a metal grid electromagnetic shielding optical window based on a single layer of positive photoresist as claimed in claim 1, characterized in that: During the stripping and degumming, an N-methylpyrrolidone aqueous solution with a mass concentration of 15% to 35% is used.

9. A metal grid electromagnetic shielding optical window based on a single layer of positive photoresist, characterized in that: The optical window is prepared by the method for preparing a metal grid electromagnetic shielding optical window based on a single-layer positive photoresist as described in any one of claims 1 to 8.

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