Functional mask plate, preparation process and application thereof

Abstract

The application relates to the technical field of mask manufacturing, and particularly discloses a functional mask, a preparation process and application thereof, wherein a buffer layer in the functional mask is directly plated on a pattern layer by magnetron sputtering before gluing, and then a wet etching process is used to remove the buffer layer corresponding to an etching position of the pattern layer. The application changes the traditional functional film preparation process, directly plates the buffer layer on the pattern layer before gluing the substrate, takes the pattern layer as a protective layer of the substrate, avoids high-energy particle bombardment on the substrate in the process of preparing the buffer layer by magnetron sputtering, effectively prevents the substrate from being damaged by impurity bombardment, and thus avoids the functional mask product from being scrapped.

Description

Technical Field

[0001] This invention relates to the field of photomask manufacturing technology, specifically to a functional photomask and its preparation process and applications. Background Technology

[0002] A photomask is an optical element consisting of a substrate and a pattern layer. It is a master template used to transfer computer-designed graphics and is widely used in exposure and batch graphic transfer processes in industries such as integrated circuits, flat panel displays, circuit boards, and touch screens. Its substrate is typically made of soda ash glass or quartz glass, and the pattern layer is usually made of chromium metal or chromium oxide.

[0003] During use, photomasks are susceptible to risks such as photoresist contamination, electrostatic discharge (ESD) damage, and scratches from foreign objects. These issues can damage the intricate patterns on the photomask, thus affecting its lifespan. To address different application needs, the photomask manufacturing industry has developed photomasks with additional functions, including anti-fouling, anti-static, and scratch resistance. Unlike traditional photomasks, these photomasks with added functions are collectively referred to as functional photomasks.

[0004] like Figure 1 As shown, existing functional photomasks typically form a buffer layer on the patterned layer using magnetron sputtering after the mask pattern is generated, usually using Si. X O Y or Si X N Y A buffer layer can increase the adhesion of functional coatings and extend their lifespan. However, during the magnetron sputtering process of depositing a buffer layer, due to impurities in the target material and fluctuations in current control, some high-energy particles may bombard the substrate, causing irreparable damage to the glass substrate and rendering it unusable. Summary of the Invention

[0005] The purpose of this invention is to provide a functional photomask, its preparation process, and its application, thereby solving the problem of glass substrate damage when forming a buffer layer on a patterned layer using magnetron sputtering in the prior art.

[0006] This invention is achieved through the following technical solution:

[0007] A process for fabricating a functional photomask, wherein the buffer layer in the functional photomask is directly deposited onto the pattern layer by magnetron sputtering before the adhesive is applied, and then the buffer layer corresponding to the etchable position of the pattern layer is removed by wet etching.

[0008] The existing method of manufacturing functional photomasks involves completing the buffer layer after the pattern has solidified. At this point, most of the glass substrate is exposed to the bombardment of high-energy particles, which can easily lead to damage defects in the glass substrate.

[0009] The application improves the existing process, completes the buffer layer before the pattern forming, and can avoid the high-energy particle bombardment to the substrate in the process of preparing the buffer layer by the magnetron sputtering under the protection of the pattern layer, reduces the damage of the substrate, and reduces the scrap.

[0010] Therefore, the application solves the problem of glass substrate damage in the process of forming the buffer layer on the pattern layer by the magnetron sputtering in the prior art.

[0011] Further, the preparation process of the functional mask plate specifically includes the following steps.

[0012] S1, depositing a pattern layer for etching a pattern on a substrate;

[0013] S2, depositing a buffer layer on the pattern layer by the magnetron sputtering;

[0014] S3, coating a resist on the buffer layer;

[0015] S4, performing photolithography on the resist to form a pattern required by the mask plate;

[0016] S5, developing the resist with the pattern after the photolithography;

[0017] S6, etching the buffer layer by a wet etching process;

[0018] S7, etching the pattern layer;

[0019] S8, removing the resist;

[0020] S9, forming a functional layer on the buffer layer.

[0021] Further, the pattern layer is a chromium layer or a chromium oxide layer or a mixed layer of chromium and chromium oxide, and the thickness of the pattern layer is 80-120 nm.

[0022] The main difficulty of the application lies in the thickness control of the film layer and the matching wet etching process. If the film layer is too thick, the transmittance of the photomask will be affected, and if the film layer is too thin, an effective surface rough layer cannot be formed.

[0023] The buffer layer can be a silicon nitride layer or a silver layer.

[0024] When the buffer layer is a silicon nitride layer, the plating film current is 3-5 A, the time is controlled within 10-15 minutes, and the film thickness is controlled within 8-15 nm. At the same time, the corresponding wet etching process is required. The specific etching process is as follows:

[0025] The buffer layer is etched by mixing 4%-10% NH4HF2 and 6%-15% hydrogen peroxide with 75%-90% deionized water, and the etching time is 60-90 s. The percentage in the formula represents the weight percentage of each substance in the etching solution.

[0026] When the buffer layer is silver layer, the thickness of the silver layer is 5-8nm (plating film current is 2-4A, time control is 6-8 minutes), 8% oxalic acid, 28% ferric nitrate, 1.5% cerous ammonium nitrate (the rest is deionized water), etching time is 40-60s. The percentage in the formula represents the weight percentage of each substance in the etching solution.

[0027] Further, 15%-30% cerous ammonium nitrate and 8%-20% nitric acid are mixed with 23%-50% deionized water to etch the pattern layer, and the etching time is 45-90s. The percentage in the formula represents the weight percentage of each substance in the etching solution.

[0028] Further, after etching the buffer layer, the mask plate is rinsed and baked at a temperature above 100℃.

[0029] Further, the functional layer includes fluorosilane polymer, antistatic agent or aluminum oxide.

[0030] Specifically, if the anti-fouling function is needed, fluorosilane polymer is evaporated; if the antistatic is needed, antistatic agent is evaporated; if the scratch resistance is needed, thin aluminum oxide is plated.

[0031] Further, the functional layer is formed on the buffer layer by vacuum evaporation.

[0032] A functional mask plate includes a substrate, a pattern layer, a buffer layer and a functional layer; the functional layer is arranged on the surface of the buffer layer and filled in the etching groove of the pattern layer and the buffer layer.

[0033] The structure of the functional mask plate of the present application is different from that of the functional mask plate prepared by the existing process. The functional mask plate prepared by the existing process is formed by etching the pattern layer to form the required pattern, and then forming the buffer layer on the pattern layer by magnetron sputtering. At this time, not only is there a buffer layer on the pattern layer, but there is also a buffer layer filled in the etching groove of the pattern layer (i.e. a buffer layer is also formed on the substrate), and the functional layer completely covers the buffer layer. The functional layer of the functional mask plate of the present application does not completely cover the buffer layer, but part of it covers the buffer layer and part of it is filled in the etching groove of the pattern layer and the buffer layer, and this part covers the substrate.

[0034] Application of a functional mask plate in the touch screen industry.

[0035] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0036] 1. In the process of the prior art magnetron sputtering buffer layer, due to the impurities of the film deposition target and the current control fluctuation, part of the high-energy particles will bombard the substrate, causing damage to the glass substrate, which cannot be repaired, resulting in scrap; the present application changes the traditional functional film manufacturing process, the buffer layer is directly plated on the pattern layer before the substrate is coated with glue, the pattern layer is used as a protective layer of the substrate, avoiding the high-energy particle bombardment on the substrate during the preparation of the buffer layer by magnetron sputtering, effectively preventing the substrate from being damaged by impurity bombardment, thereby avoiding the scrap of the mask plate product.

[0037] 2. The improvement of the preparation process of the present application not only changes the preparation sequence of the buffer layer, but also, since the buffer layer of the present application is formed on the pattern layer before the pattern is etched, in order to achieve the etching of the pattern layer to the required pattern, the buffer layer needs to be etched first, therefore, the present application also increases the etching of the buffer layer based on the existing process. Since the structure of the functional mask plate of the present application is different from the hard mask process structure of the existing semiconductor manufacturing industry, the mask plate prepared by the present application is relatively large, about 700-1000mm, wet etching method is needed to etch the buffer layer, and the thickness of the buffer layer is thinner than the silicon nitride layer in the hard mask process structure of the semiconductor manufacturing industry. Therefore, the etching of the buffer layer in the functional mask plate structure of the present application cannot be used as a reference for the existing technology, and a new buffer layer wet etching process needs to be developed based on the thickness and material of the buffer layer. The etching process of the present application can complete the etching of the buffer layer.

[0038] 3. The functional mask plate prepared by the present application is mainly applied to the manufacture of photomask in the touch screen industry, and the structure of the functional mask plate prepared by the present application has not been used in the domestic touch mask industry; the structure is to plate a buffer layer on a chromium layer, which is opposite to the use of the semiconductor hard mask. The main function of the silicon nitride in the buffer layer of the present application is to form a rough surface structure and increase the adhesion of the functional layer, which is different from the silicon nitride in the semiconductor hard mask (the function of the silicon nitride in the semiconductor hard mask is to act as an etching-resistant layer to protect the bottom metal from being damaged by the plasma etching process). BRIEF DESCRIPTION OF DRAWINGS

[0039] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0040] Figure 1 It is a process flow chart for the existing functional mask plate;

[0041] Figure 2 It is a process flow chart for the functional mask plate of the present application;

[0042] Figure 3A schematic diagram of forming a buffer layer on a pattern layer by using a magnetron sputtering method in a preparation process of a functional mask;

[0043] Figure 4 A schematic diagram of forming a buffer layer on a pattern layer by using a magnetron sputtering method in a preparation process of a functional mask;

[0044] Figure 5 A structural schematic diagram of the functional mask prepared by the present application.

[0045] Markings in the drawings and corresponding component names:

[0046] 100 - substrate; 200 - pattern layer; 300 - buffer layer; 400 - functional layer. DETAILED DESCRIPTION

[0047] To make the purpose, technical solutions and advantages of the present application clearer and more apparent, the present application is further described in detail below with reference to examples and drawings, the schematic embodiments of the present application and the descriptions thereof are only used to explain the present application, and do not limit the present application.

[0048] Example 1:

[0049] As shown in Figure 1 , the preparation process of the existing functional mask usually forms a buffer layer on the pattern layer by using a magnetron sputtering method after the mask pattern is generated, and SiO2 or SiN is usually used. X O Y or Si X N Y . The defects of the existing preparation process of the functional mask are shown in Figure 3 , in the sputtering process, impurities in the target material and the environment will bombard the substrate 100 together with Si atoms, and the substrate 100 is glass. Since the pattern on the pattern layer 200 has been formed, part of the substrate 100 is exposed, and this part is easily damaged after being bombarded by impurities, which affects the light transmission and causes the mask to be scrapped.

[0050] Therefore, the present embodiment improves the existing process as follows:

[0051] A preparation process of a functional mask, the buffer layer 300 in the functional mask is directly plated on the pattern layer 200 by using a magnetron sputtering method before gluing, and then a wet etching process is used to remove the buffer layer 300 corresponding to the etching position of the pattern layer 200. Figure 4As shown, the embodiment changes the traditional functional film production process, and directly plates the buffer layer 300 on the pattern layer 200 before the substrate 100 is coated with glue, so that the pattern layer 200 serves as a protective layer of the substrate 100, preventing the substrate 100 from being damaged by impurity bombardment, thereby avoiding the problem of mask product scrapping.

[0052] Specifically, the preparation process of the functional mask includes the following steps: Figure 2

[0053] S1, first clean the substrate 100, and then deposit a pattern layer 200 for etching patterns on the substrate 100 by using a chemical vapor deposition process, the pattern layer 200 is a chromium layer or a chromium oxide layer or a mixed layer of chromium and chromium oxide, and the thickness of the pattern layer 200 is 80-120 nm.

[0054] S2, a buffer layer 300 is plated on the pattern layer 200 by using a magnetron sputtering process.

[0055] In this embodiment, the buffer layer 300 is a silicon nitride layer, the thickness of the silicon nitride layer is 8-15 nm, the plating film current is controlled at 3-5 A during magnetron sputtering, and the time is controlled at 10-15 minutes, so that the thickness of the silicon nitride layer is 8-15 nm, and the silicon nitride layer can increase the bonding force of the functional layer 400.

[0056] S3, apply a resist on the silicon nitride layer.

[0057] S4, perform laser drawing on the resist to form a pattern required by the mask.

[0058] S5, develop the resist after the pattern is etched.

[0059] S6, etch the buffer layer 300 by using a wet etching process: specifically, etch the buffer layer 300 by using 4%-10% NH4HF2 and 6%-15% hydrogen peroxide mixed with 75%-90% deionized water, and the etching time is 60-90 s. The specific etching solution formula and etching time can be adjusted according to the specific thickness of the silicon nitride layer.

[0060] After the buffer layer 300 is etched, the mask is flushed and then baked at 110°C for 30 minutes to remove residual NH4HF2 and hydrogen peroxide, and the resist is hardened.

[0061] S7, etch the pattern layer 200: specifically, etch the pattern layer 200 by using 15%-30% cerous nitrate and 8%-20% nitric acid mixed with 23%-50% deionized water, and the etching time is 45-90 s; the specific etching solution formula and etching time can be adjusted according to the specific thickness of the pattern layer 200.

[0062] ​S8, flush water and remove the surface residual resist, complete the pattern curing; then use ultrasonic cleaning and dry the mask.

[0063] S9, form a functional layer 400 on the buffer layer 300: vacuum evaporation on the surface of the silicon nitride layer plated with the corresponding functional layer. If you need anti-fouling function, evaporation of fluorosilane polymer; if you need anti-static, evaporation of antistatic agent; if you want to scratch, you can use a thin layer of aluminum oxide.

[0064] Example 2:

[0065] The preparation process of the functional mask, comprising the following steps:

[0066] S1, first clean the substrate 100, then on the substrate 100 using chemical deposition process to deposit a layer of etching pattern for the pattern layer 200, the pattern layer 200 is chromium layer or chromium oxide layer or chromium and chromium oxide mixed layer, the thickness of the pattern layer 200 is 80nm~120nm.

[0067] S2, using magnetron sputtering on the pattern layer 200 plated a layer of buffer layer 300;

[0068] In this embodiment, the buffer layer 300 is silver layer, using magnetron sputtering on the pattern layer 200 plated a layer of silver layer:

[0069] The thickness of the silver layer is 5~8nm, the plating film current is 2~4A, the time control is 6~8 minutes.

[0070] S3, on the silicon nitride layer coated with resist.

[0071] S4, on the resist laser drawing to form the required pattern of mask.

[0072] S5, the resist after the pattern of photoetching is developed.

[0073] S6, using wet etching process to etch the buffer layer 300: using 8% oxalic acid and 28% ferric nitrate and 1.5% cerium ammonium nitrate mixed with 62.5% deionized water to etch the buffer layer 300, etching time 40~60s, the specific etching solution formula and etching time can be adjusted according to the specific thickness of the silver layer.

[0074] Silver plating can increase the antistatic effect, but the transmittance will decrease about 1%. Under normal circumstances, it does not affect the use. Silicon nitride has no antistatic effect, but the transmittance is basically not affected.

[0075] After the buffer layer 300 etching is completed, the mask is flushed and then baked at 110℃ for 30 minutes, to remove the residual oxalic acid, and to resist the film.

[0076] S7, etching the pattern layer 200: 15% to 30% of cerous nitrate and 8% to 20% of nitric acid are mixed with 23% to 50% of deionized water to etch the pattern layer 200, and the etching time is 45 to 90 seconds; the specific etching solution formula and etching time can be adjusted according to the specific thickness of the pattern layer 200.

[0077] S8, flushing and then removing the residual resist on the surface, completing the pattern curing; then using ultrasonic cleaning and drying the mask.

[0078] S9, forming the functional layer 400 on the buffer layer 300: using vacuum evaporation to plate the corresponding functional layer on the surface of the silicon nitride layer. If anti-dirt function is needed, fluorosilane polymer is evaporated; if anti-static is needed, anti-static agent is evaporated; if anti-scratch is needed, thin aluminum oxide is plated.

[0079] Example 3:

[0080] The functional mask includes a substrate 100, a pattern layer 200, a buffer layer 300 and a functional layer 400; the functional layer 400 is arranged on the surface of the buffer layer 300 and fills the etching groove between the pattern layer 200 and the buffer layer 300.

[0081] The functional mask of the embodiment is mainly applied to the manufacture of optical masks in the touch industry, and the structure has not been used in the domestic touch mask industry. The structure is to plate a buffer layer 300 (silicon nitride layer or silver layer) on a chromium layer, and the structure is opposite to the use mode of a semiconductor hard mask. The silicon nitride in the structure of the embodiment is different from the silicon nitride in the semiconductor hard mask, and the main function of the silicon nitride in the structure of the embodiment is to form a rough structure on the surface and increase the adhesion of the functional layer. The function of the silicon nitride in the semiconductor hard mask is to serve as an etching-resistant layer to protect the bottom metal from being damaged by the plasma etching process.

[0082] The improvement of the preparation process of the application not only changes the preparation sequence of the buffer layer 300, but also because the buffer layer 300 of the application is formed on the pattern layer 200 before pattern etching, in order to realize the etching of the required pattern of the pattern layer 200, the buffer layer 300 needs to be etched first, therefore, the application also increases the etching step of the buffer layer 300 on the basis of the existing process, because the structure of the functional mask of the application is different from the hard mask process structure in the existing semiconductor manufacturing industry, the mask prepared by the application is relatively large, about 700-1000mm, the buffer layer needs to be etched by wet etching, and the thickness of the buffer layer 300 is thinner than the silicon nitride layer in the hard mask process structure in the semiconductor manufacturing industry, so the etching of the buffer layer 300 in the functional mask structure of the application cannot be used as a reference for the existing technology, and a new buffer layer 300 wet etching process needs to be developed based on the thickness and material of the buffer layer 300, and the film thickness control and supporting wet etching process development are also the difficulties of the application, the application designs the wet etching process of the buffer layer according to the specific buffer layer thickness and the structure of the entire functional mask, and the wet etching process of the buffer layer is:

[0083] When the buffer layer 300 is a silicon nitride layer, the plating film current is 3-5A, the time is controlled within 10-15 minutes, and the film thickness is controlled within 8-15nm. At the same time, the corresponding wet etching process is needed. The specific etching process is:

[0084] The buffer layer is etched by mixing 4%-10% NH4HF2 and 6%-15% hydrogen peroxide with 75%-90% deionized water, and the etching time is 60-90s.

[0085] When the buffer layer 300 is a silver layer, the thickness of the silver layer is 5-8nm (plating film current 2-4A, time control within 6-8 minutes); the buffer layer 300 is etched by mixing 8% oxalic acid and 28% ferric nitrate and 1.5% cerium nitrate with 62.5% deionized water, and the etching time is 40-60s.

[0086] The above specific embodiments further illustrate the purpose, technical solutions and advantages of the application, and it should be understood that the above is only a specific embodiment of the application and does not limit the protection scope of the application, any modification, equivalent replacement, improvement, etc. within the spirit and principles of the application should be included in the protection scope of the application.

[0087] It should be noted that the structure, proportion, size, etc. shown in the drawings attached to the present specification are only used to cooperate with the content disclosed in the specification, so that those skilled in the art can understand and read, and are not used to limit the conditions that the present application can be implemented, so they do not have technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that the present application can produce, should still fall within the scope of the technical content disclosed by the present application. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and the like in the present specification are only for the convenience of clear description, and are not used to limit the scope of the present application, and the change or adjustment of the relative relationship is also considered as the implementation of the present application without substantial changes in technical content.

Claims

1. A process for preparing a functional mask, characterized in that, The buffer layer (300) in the functional mask is directly plated on the pattern layer (200) by magnetron sputtering before gluing, and then the buffer layer (300) corresponding to the etching position of the pattern layer (200) is removed by wet etching process. The buffer layer (300) is a silicon nitride layer or a silver layer. When the buffer layer (300) is a silicon nitride layer, the plating current is 3-5 A, the time is controlled within 10-15 minutes, the film thickness is controlled within 8-15 nm, and the specific etching process is that the buffer layer (300) is etched by using an etching solution mixed by 4-10 wt% NH4HF2, 6-15 wt% hydrogen peroxide and 75-90 wt% deionized water, and the etching time is 60-90 s. When the buffer layer (300) is a silver layer, the thickness of the silver layer is 5-8 nm, the plating current is 2-4 A, the time is controlled within 6-8 minutes, and the specific etching process is that the buffer layer (300) is etched by using an etching solution mixed by 8 wt% oxalic acid, 28 wt% ferric nitrate, 1.5 wt% cerium ammonium nitrate and the rest deionized water, and the etching time is 40-60 s. The method comprises the following steps: S1, depositing a pattern layer (200) for etching pattern on a substrate (100); S2, plating a buffer layer (300) on the pattern layer (200) by magnetron sputtering; S3, coating a resist on the buffer layer (300); S4, performing photoetching on the resist to form a pattern required by the mask; S5, developing the photoetched pattern resist; S6, etching the buffer layer (300) by wet etching process; S7, etching the pattern layer (200); S8, removing the resist; S9, forming a functional layer (400) on the buffer layer (300).

2. The process for preparing a functional mask according to claim 1, characterized in that, The pattern layer (200) is a chromium layer or a chromium oxide layer or a mixed layer of chromium and chromium oxide, and the thickness of the pattern layer (200) is 80-120 nm.

3. The process for preparing a functional mask according to claim 1, wherein, The pattern layer (200) is etched by using an etching solution mixed by 30 wt% cerium ammonium nitrate, 20 wt% nitric acid and 50 wt% deionized water.

4. The functional mask prepared by the preparation process according to any one of claims 1-3, comprising a substrate (100), a pattern layer (200), a buffer layer (300) and a functional layer (400); characterized in that, The functional layer (400) is arranged on the surface of the buffer layer (300) and fills in the etching groove between the pattern layer (200) and the buffer layer (300).

5. The application of the functional mask in claim 4 in the touch industry.

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