阅读说明：本技术 一种改善方片边缘膜厚的涂胶方法 (Gluing method for improving film thickness of edges of square sheets ) 是由 张德强 汤振锋 边疆 孙悦 于 2021-07-12 设计创作，主要内容包括：本发明公开了一种改善方片边缘膜厚的涂胶方法,属于光刻胶涂胶工艺技术领域。该工艺首先进行BSR背洗工艺,然后使用EBR进行方片边缘润湿,此后再进行喷胶涂覆,涂胶过程中进行关闭Cover、关闭Damper操作,成膜之后开启Cover并采用低转速甩干,保证溶剂完全挥发。该工艺可使得方片涂覆过程中保证腔体内充分的湿度,使得光刻胶在方片边缘处具有更好的流动性,在相同的曝光显影条件下可以得到更好的边缘图形。(The invention discloses a gluing method for improving the edge film thickness of a square sheet, and belongs to the technical field of photoresist gluing processes. The process comprises the steps of firstly carrying out BSR back washing, then wetting the edges of square sheets by using EBR, then carrying out glue spraying and coating, closing Cover and Damper in the gluing process, opening the Cover after film forming and drying at low rotating speed to ensure that a solvent is completely volatilized. The process can ensure sufficient humidity in the cavity in the square sheet coating process, so that the photoresist has better fluidity at the edge of the square sheet, and a better edge pattern can be obtained under the same exposure and development conditions.)

1. The gluing method for improving the edge film thickness of the square sheet is characterized by comprising the following steps of: the gluing method is used for uniformly coating the thick film photoresist on 8-inch square sheets and specifically comprises the following steps:

(1) BSR back washing process: spraying a solvent by using a back washing nozzle, wherein the square sheet is adsorbed above the sheet bearing table and rotates along with the rotation of the sheet bearing table, the solvent is uniformly dispersed in the cavity, the humidity in the cavity is increased, and meanwhile, a cavity exhaust valve (Damper) is closed to slow down the volatilization of the solvent;

(2) wetting the edges of the square pieces: wetting the edges of the square sheets (the outer sides of the inscribed circles of the square sheets) in an EBR mode, and rotating at a low rotating speed to ensure that the edges of the square sheets are fully paved with liquid;

(3) carrying out photoresist coating;

(4) closing the Cover, and performing spin coating to form a film;

(5) the Cover was turned on and rotated for a long time to ensure complete evaporation of the solvent.

2. The gluing method for improving the film thickness of the edges of the square pieces as claimed in claim 1, wherein: the thick film photoresist is the photoresist with the film thickness of less than 3 mu m coated on the wafer.

3. The gluing method for improving the film thickness of the edges of the square pieces as claimed in claim 1, wherein: in the step (1), the BSR spraying flow is 50-80 ml/min, the spraying time is 10-20 s, and the rotating speed of the square piece (wafer bearing table) is 500-3500 r/min.

4. The gluing method for improving the film thickness of the edges of the square pieces as claimed in claim 1, wherein: in the step (2), the EBR spraying flow is 5-10 ml/min, the spraying time is 10-20 s, and the wetting position is from the inner tangent circle to the edge of the square sheet.

5. The gluing method for improving the film thickness of the edges of the square pieces as claimed in claim 1, wherein: and (3) setting the glue applying amount, the glue applying speed and the rotating speed according to actual requirements when the photoresist is coated.

6. The gluing method for improving the film thickness of the edges of the square pieces as claimed in claim 1, wherein: in the step (4), the spin rate is 500-1000 r/min, and the rotation time is 20-40 s.

7. The gluing method for improving the film thickness of the edges of the square pieces as claimed in claim 1, wherein: in the step (5), when the square piece rotates for a long time, the rotating speed of the square piece is less than the glue homogenizing speed in the step (4).

8. The gluing method for improving the film thickness of the edges of the square pieces as claimed in claim 7, wherein: in the step (5), when the square sheets are rotated for a long time, the rotating speed of the square sheets is 300-600 r/min, and the rotating time is 25-40 s.

Technical Field

The invention relates to the technical field of photoresist gluing processes, in particular to a gluing method for improving the edge film thickness of a square sheet.

Background

The rapid development of flexible products in the display field makes the glass substrate become one of the important raw materials of the display panel, the square substrate is mainly used in the glass substrate, the traditional glass substrate is mainly in the glue scraping mode, but the glue coating thickness is thinner and thinner along with the development of the flexible electronic process, and the spin coating process mode becomes the best choice for low film thickness and good uniformity at present.

However, the square plate is often poor in edge uniformity and low in utilization rate during gluing, the main reason is that the photoresist is gathered due to the presence of wind veins at four corners, the photoresist starts at the position of an inscribed circle of the square plate, good gluing uniformity can be obtained in the inscribed circle, and annular wind veins can be seen outside the inscribed circle. The main causes of the uneven film thickness are caused by centrifugal force and unstable wind flow in irregular areas outside the inscribed circle.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a method for improving the edge film thickness of a square sheet, which accelerates the surface fluidity of a photoresist on the square sheet by increasing the internal environment humidity of a gluing cavity, and particularly improves the edge film thickness of the square sheet at positions outside an inscribed circle at the edge, so that 8-inch square sheet wind marks are reduced from 45mm to 20mm, and a good pattern effect can be obtained at the edge under the same exposure and development conditions.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a gluing method for improving the edge film thickness of a square sheet is used for uniformly coating thick film photoresist on an 8-inch square sheet, and the gluing process specifically comprises the following steps:

(1) BSR back wash process (back photoresist removal process): spraying a solvent by using a back washing nozzle, wherein the square sheet is adsorbed above the sheet bearing table and rotates along with the rotation of the sheet bearing table, the solvent is uniformly dispersed in the cavity, the humidity in the cavity is increased, and meanwhile, a cavity exhaust valve (Damper) is closed to slow down the volatilization of the solvent;

(2) wetting the edges of the square pieces: wetting the inner tangent circle and the outer tangent circle of the edge of the square sheet in an EBR mode, and rotating at a low rotating speed to ensure that the edge of the square sheet is fully paved with liquid;

(3) carrying out photoresist coating;

(4) closing the Cover, and performing spin coating to form a film.

(5) The Cover was turned on and rotated for a long time to ensure complete evaporation of the solvent.

The thick film photoresist is the photoresist with the film thickness of less than 3 mu m coated on the wafer.

In the step (1), the BSR spraying flow is 50-80 ml/min, the spraying time is 10-20 s, and the rotating speed of the square piece (wafer bearing table) is 500-3500 r/min.

In the step (2), the EBR spraying flow is 5-10 ml/min, the spraying time is 10-20 s, and the wetting position is from the inner tangent circle to the edge.

In the step (3), photoresist coating is performed, and the glue applying amount, the glue applying rate and the rotating speed are set according to actual conditions.

In the step (4), the spin rate is 500-1000 r/min, and the rotation time is 20-40 s.

In the step (5), when the rotating speed is long, the rotating speed is preferably 300-600 r/min less than the glue homogenizing speed in the step (4), and the rotating time is 25-40 s.

The invention has the following advantages and beneficial effects:

the invention provides a gluing process for coating a volatile photoresist with a small viscosity coefficient on the surface of a square sheet, which adopts a mode of firstly adding BSR and then adding EBR under the conditions of Cover and Damper and finally spraying and spin-coating the photoresist. On one hand, the BSR is added, the Cover is closed and the Damper is closed, so that the volatilization degree of the solvent is reduced, the humidity of the cavity is increased, and on the other hand, the fluidity of the photoresist at the edge is enhanced through the wetting of the EBR. The process structure subverts the functions of cleaning wafer back dirt and EBR trimming of the traditional BSR, redefines the functions of the BSR in the square sheet gluing formula from the angles of increasing the cavity humidity and increasing the edge fluidity by the EBR, and further achieves the effect of improving the edge thickness of the square sheet.

Drawings

Fig. 1 is a schematic view of a gluing unit used in the present invention.

FIG. 2 is a formula of an embodiment of the present invention.

FIG. 3 is a diagram showing the gluing result of the example.

FIG. 4 is a graph showing the results after exposure and development in the examples.

Fig. 5 is a formula diagram of comparative example 1.

Fig. 6 is a graph showing the result of the gluing in comparative example 1.

FIG. 7 is a graph showing the results after exposure and development of comparative example 1.

Detailed Description

The invention is described in detail below with reference to the accompanying drawings and examples.

The invention provides a method for improving the gluing thickness of the edges of square sheets, and a schematic diagram of a gluing unit used in the process is shown in figure 1. The 8-inch glass substrate square sheet is placed on a sheet bearing table, and the sheet bearing table can drive the square sheet to rotate clockwise; the glue coating nozzle and the EBR nozzle can translate above the cavity and spray photoresist; the BSR is directly opened in the cavity; the upper Cover can be dropped on the CUP to form a closed cavity.

The square piece coating process in the following examples was performed on a 8-inch glass substrate square surface coated with a 1.7 μm thick photoresist, and the recipe is shown in fig. 2, and includes the following steps:

example 1:

step 1: the square piece rotates along with the wafer bearing platform, the solvent is sprayed with OK73 by BSR, the flow rate is 65ml/min, the spraying time is 10s, and the rotation speed of the wafer bearing platform is 1000 r/s.

Step 2: and (3) closing the BSR, rotating the wafer bearing platform at the rotating speed of 1000r/s for 10s, and mainly drying the solvent on the back surface of the square wafer in the step 1.

Step3& 4: EBR wets the inner circle and outer area of the square sheet, the flow rate is 10ml/min, the rotation speed of the wafer bearing platform is 200r/s, and the rotation time is 10 s.

Step 5: the glue is applied, the flow rate is 2ml, and the speed is 1 ml/s.

Step6& 7: the glue arm returns to the start position, and the Cover is closed.

Step 8: the glue is homogenized to form a film, and the rotation speed of the wafer bearing platform is 700r/s and 25 s.

Step 9: and (5) turning on the Cover, rotating the wafer bearing table at the rotating speed of 400r/s for 25s, and ensuring that the surface solvent is fully volatilized.

In this embodiment, for the photoresist with a thickness within 3 μm, the effect is excellent in reducing the moire at the edge of the square piece, reducing the defect, and improving the surface uniformity of the square piece, compared with the comparative example, the moire width can be reduced to within 20mm, the result is schematically shown in fig. 3, the edge residual photoresist can be completely removed under the same subsequent exposure and development process, and the result after exposure and development is schematically shown in fig. 4.

Comparative example 1:

in this example, the conventional process is used to perform square sheet gluing, and the formula is shown in fig. 5, and the specific implementation manner is as follows:

step1& 2: the square sheet rotates along with the sheet bearing table, the gluing nozzle is adopted to move to a position right above the center of the square sheet, and photoresist is coated at the center of the square sheet; the moving speed is 100mm/s, the glue amount is 3ml, the glue coating speed is 1ml/s, and the rotating speed of the wafer bearing platform is 20 r/s.

Step 3: after the glue is coated, the glue is homogenized at a high rotating speed for 1000r/s for 25 s.

Step 4: and (4) starting a BSR (buffer status report) for back washing, wherein the flow is 50ml/min, the time is 10s, and the rotating speed of the wafer bearing platform is 800 r/s.

Step 5: spin-drying, closing the BSR, and rotating the wafer bearing platform at the speed of 1000r/s for 10 s.

In this example, Damper is opened, Cover is opened all the way through, and the width of the air pattern after gluing is about 45mm, and the result is schematically shown in FIG. 6. After exposure and development, there was residual glue at the edge, and the result is schematically shown in FIG. 7.

The gluing process can ensure sufficient humidity in the cavity in the square sheet coating process, so that the photoresist has better fluidity at the edge of the square sheet, and a better edge pattern can be obtained under the same exposure and development conditions. The BSR on time, flow rate, rotation speed, EBR on time, rotation speed, movement position, movement speed of the glue arm, glue amount, and glue rate may be different from the above parameters depending on the viscosity coefficient, film thickness, and the like of the photoresist, but may be modified within the scope of the technical framework of the present invention described above.