Developing method

Abstract

The invention provides a developing method. The developing method comprises the following steps: mounting an exposed wafer on a machine table; adjusting the pre-wetting nozzle to an initial position, wherein the initial position deviates from the center of the wafer; enabling the wafer to be in a rotating state; the pre-wetting nozzle sprays pre-wetting liquid to the surface of the wafer while moving from the initial position to the center of the wafer; and spraying a developing solution to the surface of the wafer through the developing solution nozzle to enable the developing solution to cover the surface of the wafer. According to the developing method provided by the invention, the pre-wetting nozzle is adjusted to the initial position, and the initial position and the center of the wafer have offset, so that the pre-wetting liquid can be better mixed with the developing solution during spraying, and the concentration uniformity of the developing solution at each part of the wafer is improved; and the risk that the wafer has defects after development due to too low concentration of the developing solution is reduced.

Description

Technical Field

[0001] The present invention relates to a developing method. Background Art

[0002] Development is an important process step in the photolithography process. Before the development process, the developer needs to be sprayed on the wafer. The spraying method of the developer will be different depending on the type of photoresist, the film thickness of the photoresist and different types of photolithography machines.

[0003] In order to make the eye shadow liquid spread better on the surface of the wafer and facilitate the reaction between the developer and the photoresist, deionized water is used to pre-wet the wafer surface before spraying the developer to improve the adhesion between the developer and the wafer.

[0004] The conventional wafer surface is pre-wetted before spraying a developer for development. This may result in development defects in the center of the wafer, which are manifested as holes with development defects on the wafer surface being shallower than holes with normal development. Summary of the invention

[0005] The object of the present invention is to provide a developing method, which has the advantage of less wafer defects after development.

[0006] To achieve the above object, the present invention provides a developing method, which comprises:

[0007] Mount the exposed wafer on the machine;

[0008] Adjusting the pre-wetting nozzle to a starting position, wherein there is an offset between the starting position and the center of the wafer;

[0009] Putting the wafer into a rotating state;

[0010] The pre-wetting nozzle moves from the starting position toward the center of the wafer while spraying the pre-wetting liquid onto the surface of the wafer;

[0011] The developer is sprayed onto the wafer surface through a developer nozzle so that the developer covers the wafer surface.

[0012] Preferably, along the radial direction of the wafer, the offset distance between the starting position and the center of the wafer is not less than 50 mm.

[0013] Preferably, along the radial direction of the wafer, the distance between the pre-wetting starting position and the center of the wafer is 60-90 mm.

[0014] Preferably, along the radial direction of the wafer, the horizontal moving speed of the pre-wetting nozzle toward the center of the wafer is 150 mm / s to 300 mm / s.

[0015] Preferably, along the radial direction of the wafer, the horizontal moving speed of the pre-wetting nozzle toward the center of the wafer is 200 mm / s to 300 mm / s.

[0016] Preferably, the height between the pre-wetting nozzle and the wafer surface is 1.2 mm to 1.5 mm.

[0017] Preferably, the diameter of the wafer is not less than 8 inches.

[0018] Preferably, the pre-wetting liquid is deionized water.

[0019] Preferably, the wafer is a CMOS image sensor wafer.

[0020] In summary, compared with the prior art, the developing method provided by the present invention has the following beneficial effects:

[0021] The developing method of the present invention adjusts the pre-wetting nozzle to the starting position, and there is an offset between the starting position and the center of the wafer, so that the pre-wetting liquid can be better mixed with the developer during spraying, thereby improving the uniformity of the developer concentration at various locations on the wafer and reducing the risk of defects in the wafer after development due to too low a developer concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the pre-wetting nozzle of the present invention spraying pre-wetting liquid onto the surface of a wafer.

[0023] Description of reference numerals:

[0024] Pre-wetted nozzle 10

[0025] Wafer 20

[0026] Pre-wetting liquid 30 DETAILED DESCRIPTION

[0027] The following will be combined with the attached embodiment of the present invention Figure 1 , the technical solutions, structural features, objectives achieved and effects in the embodiments of the present invention are described in detail.

[0028] It should be noted that the drawings are in a very simplified form and use non-precise proportions. They are only used to conveniently and clearly assist in explaining the embodiments of the present invention, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention.

[0029] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only the elements explicitly listed, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0030] The present invention provides a developing method, which comprises at least the following steps:

[0031] During the processing of the wafer, it is necessary to go through the steps of coating, exposure, and development. Coating refers to applying photoresist on the surface of the wafer 20. The photoresist is sensitive to light of a certain wavelength. After the photoresist is applied to the wafer 20, the wafer 20 is exposed. Exposure refers to irradiating the wafer coated with photoresist with light of a certain wavelength. The properties of the photoresist on the wafer 20 change after being irradiated with light. The exposed wafer 20 is mounted on the machine to prepare for developing the exposed wafer 20. During the development process, the developer needs to be sprayed on the surface of the wafer 20. In order to improve the adhesion between the developer and the wafer 20, the wafer 20 is usually pre-wetted. In this embodiment, the pre-wetting liquid 30 selected is deionized water.

[0032] First, the pre-wetting nozzle 10 is adjusted to the starting position. There is an offset between the starting position and the center of the wafer 20. In order to avoid the pre-wetting liquid 30 being concentrated in the center of the wafer 20, the developer is dripped onto the wafer surface after the pre-wetting liquid is added to the wafer surface. The concentration of the developer at the center of the wafer 20 after mixing with the pre-wetting liquid is lower than the concentration of the developer in the surrounding area after mixing with the pre-wetting liquid, which leads to abnormal development of the wafer 20 due to the low concentration of the developer during the development process, resulting in defects in the wafer 20 after the final processing is completed.

[0033] After the position of the pre-wetting nozzle 10 is adjusted, the wafer 20 is driven to start rotating, so that the wafer 20 is in a rotating state. When the wafer 20 is in a rotating state, the pre-wetting liquid 30 is sprayed onto the surface of the wafer 20, so that the pre-wetting liquid 30 is dispersed more evenly on the surface of the wafer 20, avoiding the pre-wetting liquid 30 from being concentrated on the surface of the wafer 20. For the developer subsequently sprayed on the surface of the wafer 20, the uniformity of the concentration of the developer after mixing with the pre-wetting liquid 30 can be improved.

[0034] When the wafer 20 is in a rotating state, the pre-wetting nozzle 10 is further controlled to move from the starting position to the center of the wafer 20, and the pre-wetting nozzle 10 always sprays the pre-wetting liquid 30 onto the surface of the wafer 20 during the movement. During the spraying process, the pre-wetting nozzle 10 makes a reciprocating linear motion along the radial direction of the wafer 20, and the wafer 20 makes a rotational motion around its own axis, so that the pre-wetting liquid 30 is sprayed on the surface of the wafer 20 as evenly as possible, thereby improving the uniformity of the concentration of the developer and the pre-wetting liquid 30 after mixing on the wafer 20.

[0035] The developer is sprayed onto the surface of the wafer 20 through the developer nozzle so that the developer covers the surface of the wafer 20 . After the pre-wetting liquid 30 has been sprayed onto the surface of the wafer 20 , the developer is sprayed onto the surface of the wafer 20 again so that the developer and the pre-wetting liquid 30 are evenly mixed on the surface of the wafer 20 .

[0036] Along the radial direction of the wafer 20, the offset distance between the starting position of the pre-wetting nozzle 10 and the center of the wafer 20 is not less than 50 mm. If the distance between the starting position of the pre-wetting nozzle 10 and the center of the wafer 20 is too small, the pre-wetting liquid 30 cannot be evenly dispersed on the surface of the wafer 20. The offset distance between the starting position of the pre-wetting nozzle 10 for spraying the pre-wetting liquid 30 and the center point of the wafer 20 is controlled to be not less than 50 mm to ensure that the pre-wetting liquid 30 can be sprayed on the surface of the wafer 20 within a sufficiently large range.

[0037] A preferred option is to control the distance between the pre-wetting start position and the center of the wafer 20 to be 60-90 mm along the radial direction of the wafer 20. In this embodiment, the distance between the pre-wetting start position and the center of the wafer 20 is selected to be 80 mm.

[0038] In order to reduce the possibility of defects in the wafer 20 after processing, the horizontal moving speed of the pre-wetting nozzle 10 toward the center of the wafer 20 along the radial direction of the wafer 20 is 150 mm / s to 300 mm / s.

[0039] In order to further reduce the possibility of defects after processing the wafer 20, the horizontal moving speed of the pre-wetting nozzle 10 toward the center of the wafer 20 is controlled within the range of 200 mm / s to 300 mm / s along the radial direction of the wafer 20. In this embodiment, the horizontal moving speed of the pre-wetting nozzle 10 toward the center of the wafer 20 is set to 250 mm / s.

[0040] In order to prevent the pre-wetting liquid 30 from dripping from the pre-wetting nozzle 10 and falling on the target area on the wafer 20, the height of the pre-wetting nozzle 10 from the surface of the wafer 20 is 1.2mm~1.5mm. If the distance between the pre-wetting nozzle 10 and the surface of the wafer 20 is too close, there may be a risk of the pre-wetting nozzle 10 contacting the surface of the wafer 20. If the distance between the pre-wetting nozzle 10 and the surface of the wafer 20 is too large, the pre-wetting liquid 30 may fail to drip onto the target area on the wafer 20.

[0041] The diameter of the wafer 20 is not less than 8 inches. If the diameter of the wafer 20 is too small, the starting position of the pre-wetting nozzle 10 will exceed the boundary of the wafer 20, causing the pre-wetting liquid 30 to drip outside the wafer 20, thereby causing incomplete mixing of the pre-wetting liquid 30 and the developer. In order to ensure the mixing effect between the pre-wetting liquid 30 and the developer, the diameter of the applicable wafer 20 is not less than 8 inches.

[0042] The wafer 20 is a CMOS (Complementary Metal-Oxide-Semiconductor) image sensor wafer 20 .

[0043] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A developing method, It is characterized in that At least: Mount the exposed wafer on the machine; Adjusting the pre-wetting nozzle to a starting position, wherein there is an offset between the starting position and the center of the wafer; Putting the wafer into a rotating state; The pre-wetting nozzle moves from the starting position toward the center of the wafer while spraying the pre-wetting liquid onto the surface of the wafer; The developer is sprayed onto the wafer surface through a developer nozzle so that the developer covers the wafer surface.

2. The method according to claim 1, It is characterized in that Along the radial direction of the wafer, the offset distance between the starting position and the center of the wafer is not less than 50 mm.

3. The method according to claim 2, It is characterized in that Along the radial direction of the wafer, the distance between the pre-wetting starting position and the center of the wafer is 60-90 mm.

4. The method according to claim 1, It is characterized in that Along the radial direction of the wafer, the horizontal moving speed of the pre-wetting nozzle toward the center of the wafer is 150 mm / s to 300 mm / s.

5. The method as claimed in claim 4, It is characterized in that Along the radial direction of the wafer, the horizontal moving speed of the pre-wetting nozzle toward the center of the wafer is 200 mm / s to 300 mm / s.

6. The method according to claim 1, It is characterized in that The height of the pre-wetting nozzle from the wafer surface is 1.2 mm to 1.5 mm.

7. The method according to claim 1, It is characterized in that The diameter of the wafer is not less than 8 inches.

8. The method according to claim 1, It is characterized in that The pre-wetting liquid is deionized water.

9. The method according to claim 1, It is characterized in that The wafer is a CMOS image sensor wafer.

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