Anisotropic metal thin film photolithography process

Abstract

The application discloses a special-shaped metal film photoetching process, wherein a photoetching surface of a ceramic substrate is a slope surface, a photoetching plate for exposure and development is a flexible film, and a metal film is sputtered titanium platinum gold, the photoetching process comprises the following steps: glue spraying, glue surface detection, exposure and development, sputtering and post-processing, and the photoetching process for metal plating on the special-shaped body adopts an optimized photoetching technology; wherein the photoetching plate is used instead of a hard plate by using a flexible film, and a glue spraying process is used instead of a uniform glue process, so that the bonding force and uniformity of a product connecting part and a slope surface plating layer area are better.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal thin film photoetching, and particularly relates to a special-shaped metal thin film photoetching process. BACKGROUND

[0002] Photoetching is a process technology for transferring the pattern on a mask plate to a wafer by using photochemical reaction principle and chemical and physical etching methods. The principle of photoetching originates from photographic plate making in printing technology, and is to process micro-patterns on a plane. Photoetching is mainly divided into optical photoetching and particle beam photoetching (common particle beam photoetching mainly includes X-ray, electron beam and ion beam photoetching) according to the exposure light source. Among them, optical photoetching is the most important photoetching technology at present, and its mainstream position will still be unshakable in the next few years.

[0003] The main difficulty and key point is to perform metallization on the slope surface of the special-shaped body. The current surface metallization process is mainly for flat surfaces. Using the traditional process to perform metallization on the inclined surface will cause pattern missing, multi-angle and pattern deformation, and the current surface metallization process needs to be changed and optimized.

[0004] For such special products, screen printing technology is usually used because photoetching process is generally used on flat surfaces, and the effect of special-shaped or curved surfaces is much worse than that of flat surfaces. However, the line width and line spacing required by this product are small, and the product precision requirement is high. The precision of screen printing technology is low, which can easily cause the electrode at the connection to be disconnected, and cannot meet the requirements. When using photoresist, the most commonly used method for coating is uniform coating. A typical uniform coating process includes the steps of dropping, high-speed rotation and drying (solvent evaporation). The photoresist is dropped on the surface of the product, and then the photoresist is uniformly distributed on the surface of the product by high-speed rotation. However, this product is a special-shaped product, and the surface to be photoetched is not a flat surface but a slope surface. Uniform coating will cause uneven coating of the surface. SUMMARY

[0005] In order to solve the above problems, the present application provides a special-shaped metal thin film photoetching process. The photoetched surface of the ceramic substrate is a slope surface, the photoetched plate for exposure and development is a flexible film, and the metal thin film is sputtered titanium platinum gold. The photoetching process includes spraying, detecting the glue surface, exposure and development, sputtering and post-processing, and the specific process steps are as follows.

[0006] a. Place the ceramic substrate with the photoetched surface upward on the heating workbench for heating;

[0007] b. Spray the photoresist liquid on the photoetched surface of the ceramic substrate;

[0008] c. Accelerate the volatilization of the solvent on the surface of the heated ceramic substrate;

[0009] d, rotating the ceramic substrate and spraying again, spraying four times in front and back;

[0010] e, detecting the sprayed glue surface;

[0011] f, using a mask contact type to expose and develop the lithography surface;

[0012] g, using sputtering titanium platinum gold to perform sputtering process after lithography;

[0013] h, performing weak alkali and laser scanning on the sputtered ceramic substrate to complete post-processing.

[0014] The photoresist used herein is not a dry film, the product size herein is small and the surface is uneven, the dry film cannot completely cover the surface, the line width and line spacing of the pattern required herein are small, and the dry film is prone to cause the electrode to disconnect at the connection, while the photoresist can be evenly distributed on the uneven product surface.

[0015] When using photoresist, uniform coating is the most commonly used coating method, a typical uniform coating process includes dropping, high-speed rotation and drying (solvent evaporation) steps, the photoresist is dropped on the product surface in an appropriate amount, and then the photoresist is evenly distributed on the product surface by high-speed rotation, but this product is an uneven product, and the surface to be lithographed is not a plane but a slope, uniform coating will cause uneven coating of the surface, and pinhole-like point leakage and area leakage will occur, therefore, the photoresist is sprayed in this paper, in addition to having very high photoresist coating efficiency, the spraying process can solve some problems that cannot be solved by uniform coating on uneven product surfaces, such as the need for high coverage of the product edge, and the use of the spraying process on uneven substrates can obtain uniform film thickness on the pattern groove, sidewall and edge.

[0016] The invention adopts high-pressure gas atomization, and the atomized photoresist droplets are splashed onto the product surface, and in the process of flying, the solvent in the photoresist volatilizes, and after the volatilized droplets accumulate, a thin film with uniform thickness is formed. Place the product on the workpiece table and heat it to the process temperature. Heating can accelerate the volatilization of the solvent after the photoresist droplets are on the product surface, so that the fluidity of the photoresist is minimized to more closely cover the surface of the uneven body. The nozzle sprays photoresist on the product surface, while the mechanical arm drives the nozzle to perform S-shaped scanning in the X / Y plane, covering the entire surface of the desired area, so that the entire surface is evenly covered with photoresist. For the uneven structure area of the uneven body, the direction of the uneven structure is different, and the amount of sprayed photoresist is different, different directions will cause shielding, resulting in a large difference in the amount of photoresist. By rotating the product and spraying again, spraying four times in front and back, the photoresist layer with sufficient thickness and uniform thickness can be covered in each direction.

[0017] After the glue spraying is completed, the product needs to be inspected for the state after the glue spraying. There may be a little point leakage at the product joint. If there is a little leakage, the glue needs to be supplemented, and the subsequent exposure and development will not have a leakage exposure.

[0018] Generally, exposure has mask alignment exposure, step projection exposure, laser direct writing, electron beam direct writing, etc. The conventional use is mask alignment exposure and step projection exposure. The product made by the invention is a special-shaped slope. Step projection exposure needs a mask to obtain a pattern. There is a projection system between the mask and the photoresist. The pattern is exposed on the photoresist according to a certain proportion. It is not easy to expose on the curved surface, which will cause the pattern to deform and be missing. Therefore, the invention adopts mask alignment exposure, which needs a mask to obtain a pattern. The mask pattern and the photoresist pattern have a 1:1 relationship. Generally, it is contact type and proximity type. Since the invention needs to be performed on a zigzag slope, the proximity mask has a certain distance from the product, and the surface of the product is not a plane, which will cause the pattern to deform, be missing, and have multiple angles during exposure. Therefore, the invention adopts contact type, which can restore the required pattern on the zigzag slope with 1:1 and reduce the pattern deformation, missing, and multiple angles. It is to draw air between the mask and the substrate to make them better fit.

[0019] The mask of a single product is fixed on the surface of the product, and then multiple products are spliced. The periphery of the product does not need to be metallized. This tooling can also well shield the periphery of the product.

[0020] The most core of exposure is the light source. Common light sources include ultraviolet light (UV), deep ultraviolet light (DUV), and extreme ultraviolet light (EUV). The invention adopts ultraviolet light (i-line: 365nm). Uv ultraviolet light includes g-line (436nm) and i-line (365nm). For ultraviolet light, the shorter the wavelength, the smaller the feature size that can be exposed. Therefore, the invention adopts ultraviolet light (i-line: 365nm).

[0021] After exposure and development, titanium platinum gold sputtering is performed. Titanium platinum gold has better adhesion to aluminum nitride substrates than chromium nickel gold, and is more conducive to subsequent sputtering post-processing, making the pattern restoration degree higher.

[0022] After titanium platinum gold sputtering, the surface of the product is inspected. Some products have electrode sticking. Laser scanning is adopted. However, considering that the aluminum nitride may lose nitrogen ions after laser scanning, it also needs to be etched with weak alkali. At this time, the platinum in titanium platinum gold has better acid and alkali resistance.

[0023] Advantages:

[0024] The metalization photoetching process on the special-shaped body uses optimized photoetching technology; wherein the photoetching plate uses a film soft plate instead of a hard plate, and uses a spraying glue process instead of a uniform glue process, so that the bonding force and uniformity of the plated area of the product connection and slope are better.

[0025] The line width and line spacing of the pattern are small, and the dry film is prone to cause the electrode to disconnect at the connection, while the photoresist can be uniformly distributed on the surface of the special-shaped product.

[0026] In addition to having very high photoresist coating efficiency, the spraying glue process can solve some problems that cannot be obtained on the uneven product surface by uniform glue or require higher product edge coverage, and using the spraying process on the uneven substrate can obtain uniform film thickness in the pattern groove, sidewall and edge.

[0027] For the area of the special-shaped body with undulating structure, the undulating structure has different orientations, and the amount of sprayed photoresist is different. Different orientations will cause shielding, resulting in a large difference in the amount of photoresist. By rotating the product and spraying again, after four times of spraying, each orientation can cover a photoresist layer with sufficient thickness and uniform thickness.

[0028] Since the invention needs to be performed on a zigzag slope, the proximity mask plate has a certain distance from the product, and the product surface is not a plane, which can cause pattern deformation, pattern missing and pattern multi-angle during exposure. Therefore, the invention uses a contact type, which can reproduce the required pattern on the zigzag slope with 1:1 and reduce pattern deformation, pattern missing and pattern multi-angle. Vacuum is drawn between the mask and the substrate to better adhere.

[0029] Laser scanning is used, but considering that after the aluminum nitride is scanned by the laser, there may be nitrogen ions lost, and a weak alkali is also needed to etch the aluminum nitride substrate. At this time, the platinum in titanium platinum gold has better acid and alkali resistance. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic diagram of a ceramic substrate structure of a special-shaped metal thin film photoetching process.

[0031] Figure 2 It is a schematic diagram of a photoetching plate pattern of a special-shaped metal thin film photoetching process. DETAILED DESCRIPTION

[0032] In order to deepen the understanding of the invention, the invention will be further described below in combination with examples and drawings, which are only used to explain the invention and do not constitute a limitation on the protection scope of the invention.

[0033] As shown in Figure 1 , 2 ;

[0034] The dry film cannot completely cover the small product size and the uneven surface of the product herein, the line width and line spacing of the pattern required herein are small, and the dry film is prone to cause the electrode to be disconnected at the connection. The photoresist can be uniformly distributed on the uneven product surface; the photoresist is sprayed in the process, and the uniform coating method will cause the photoresist to accumulate at the turning area of the uneven body slope, resulting in uneven distribution of the photoresist on the entire product surface. After optimization of the glue concentration, temperature, flow rate, spraying movement speed and ultrasonic power, the photoresist is sprayed; after the spraying of the photoresist is completed, the state of the product after the spraying needs to be checked. There may be a little point-shaped glue leakage at the joint of the product. If there is a little glue leakage, the glue needs to be supplemented, and there will be no exposure leakage after subsequent exposure and development; after the inspection is completed, exposure and development are performed. Exposure on the curved surface will cause the pattern to deform or be exposed, so contact exposure is adopted for mask alignment exposure. The pattern required by the product can be better restored 1:1. Since the product is a zigzag plane, the line length is appropriately lengthened after calculation, the mask plate of a single product is fixed on the product surface, and multiple products are placed in a special tool for layout; after exposure and development, titanium platinum gold is sputtered. Titanium platinum gold has better bonding force with aluminum nitride substrate than chromium nickel gold, and is more conducive to subsequent sputtering post-processing, so that the pattern restoration degree is higher; after sputtering titanium platinum gold, the product surface is checked, and some products have electrode sticking. Laser scanning is adopted, but considering that the aluminum nitride may lose nitrogen ions after laser scanning in the later stage, it also needs to be etched by weak alkali. At this time, the platinum in the titanium platinum gold has better acid and alkali resistance.

[0035] Embodiment example

[0036] a. Place the ceramic substrate with the photoetched surface facing up on the heating workbench for heating;

[0037] b. Spray the photoresist liquid on the photoetched surface of the ceramic substrate in a glue spraying manner;

[0038] c. After heating, the ceramic substrate accelerates the volatilization of the solvent on the surface of the photoresist liquid;

[0039] d. Rotate the ceramic substrate and spray again. After four times of spraying;

[0040] e. Detect the glue surface after spraying;

[0041] f. Use a mask plate to contact the photoetched surface for mask alignment exposure and development;

[0042] g. Use sputtered titanium platinum gold to perform sputtering process after photoetching;

[0043] h. Perform weak alkali and laser scanning on the sputtered ceramic substrate to complete the post-processing.

[0044] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A special-shaped metal thin film photoetching process, the photoetched surface of a ceramic substrate is a slope, the photoetching plate exposed and developed is a flexible film, and the metal thin film is sputtered titanium platinum gold, characterized in that, The photoetching process comprises glue spraying, glue surface detection, exposure and development, sputtering and post-processing, and the specific process steps are as follows: a. Place the ceramic substrate with the photoetched surface upwards on the heating workbench for heating; b. Spray the photoetching glue liquid on the photoetched surface of the ceramic substrate; c. After heating, the ceramic substrate makes the photoetching glue liquid accelerate the volatilization of the solvent on the surface; d. Rotate the ceramic substrate and spray again, four times before and after spraying; e. Detect the sprayed glue surface; f. Use the mask contact type to perform mask alignment exposure and development on the photoetched surface; g. Use sputtering titanium platinum gold to perform sputtering process after photoetching; h. Perform weak alkali and laser scanning on the sputtered ceramic substrate to complete the post-processing; The pattern of the mask is the same as that of the photoetching glue, the bottom surface of the mask is air suction type and is attached to the ceramic substrate, the light source for exposure and development is ultraviolet light, and the ultraviolet light is i-line 365nm type.

2. A photoetching process of a profiled metal film according to claim 1, characterized in that, The heating workbench is a rotary clamping workbench, the surface of the heating workbench is provided with a clamping clamp, the bottom surface of the heating workbench is provided with a heating surface, and the material of the ceramic substrate is aluminum nitride.

3. A photoetching process of a profiled metal film according to claim 1, characterized in that, The photoetching glue is sprayed on the photoetched surface through a spray head, the spray head is a mechanical arm moving type spray head, and the mechanical arm drives the nozzle to perform S-shaped scanning in the X / Y plane.

4. The photoetching process of claim 1, wherein, The exposure and development position is provided with an exposure tool, and the exposure tool is externally wrapped around the outer side of the ceramic substrate.

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