Wafer processing method
By exposing grooves on the wafer and separating the chip by secondary wet etching, the problems of large stress and deformation caused by mechanical cutting are solved, and a higher yield rate and longer chip service life is achieved.
Patent Information
- Application Number
- CN202311079765.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-25
- Publication Date
- 2025-02-25
AI Technical Summary
The existing semiconductor cutting methods cause large stress in the wafer through mechanical processing, causing deformation, affecting the working performance of the internal integrated circuit of the chip and increasing the bad product rate.
The secondary wet etching method is used instead of mechanical cutting, by exposing the grooves on the first and second surfaces of the wafer, wet etching the grooves on both surfaces, until the wafer is separated into independent chips along the grooves.
It effectively reduces the stress during wafer separation, reduces the deformation of semiconductors, improves the yield rate of the product, and improves the performance and service life of the chip through efficient cleaning and drying.
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a wafer processing method. Background Art
[0002] With the advancement of semiconductor technology, chips are becoming thinner, the density of chips on wafers is getting higher and higher, and the cutting position between chips is getting narrower and narrower. At present, semiconductor cutting methods are generally achieved through mechanical processing. For example, the wafer cutting process requires grinding and thinning the bottom of the wafer, and then cutting the wafer with a rotating grinding wheel tool. In the process of cutting, it is easy to cause internal stress in the wafer semiconductor and cause deformation. However, whether it is mechanical grinding and thinning or mechanical cutting on the front side, it will cause large internal stress, which will cause the semiconductor to deform. Excessive deformation will affect the working performance of the integrated circuit inside the chip, increase the defective rate, and is not conducive to production needs.
[0003] Therefore, it is urgent to provide an improved wafer processing method to overcome the above defects. Summary of the invention
[0004] The object of the present invention is to provide an improved wafer processing method to avoid mechanical cutting and greatly reduce the stress generated when the wafer is separated, thereby reducing the deformation of the semiconductor and improving the yield rate of the product.
[0005] To achieve the above object, the wafer processing method of the present invention comprises the following steps:
[0006] Protecting a first surface and a second surface of a wafer, exposing the groove on the first surface of the wafer;
[0007] Placing the first surface of the wafer in a silicon etching solution to wet-etch the groove, wherein the groove is etched to a first depth;
[0008] Placing the second surface of the wafer in a silicon etching solution to wet-etch the back side of the groove, wherein the groove is etched to a second depth, and the sum of the first depth and the second depth is suitable for separating the wafer into independent chips along the groove;
[0009] The independent chip is placed in a mixture of ammonia, hydrogen peroxide and deionized water for cleaning; and
[0010] The individual chips are dried.
[0011] Compared with the prior art, the present invention first protects the wafer to expose only the groove on the first surface, and after the first wet etching, the groove is corroded to the first depth, and then the back of the groove is wet-etched for the second time to further corrode the groove until the wafer is separated into independent chips along the groove. The use of secondary wet etching to replace the processing method of mechanical cutting can avoid excessive deformation caused by mechanical cutting, protect the working performance of the integrated circuit inside the chip, and ensure the yield rate. Moreover, the chips separated by wet etching are efficiently cleaned and dried, which further improves the performance of the chip and extends its service life. The mixed solution of ammonia water, hydrogen peroxide and deionized water is simple and easy to obtain, and has low cost.
[0012] Preferably, the method further comprises: coating photoresist on the first surface and the second surface of the half wafer and exposing the groove.
[0013] Preferably, the method further comprises: the photoresist covers the side walls of the groove and only exposes the bottom wall of the groove.
[0014] Preferably, the silicon etching solution is a mixture of nitric acid, glacial acetic acid and hydrofluoric acid. More preferably, the ratio of nitric acid: glacial acetic acid: hydrofluoric acid is 7:1:1. More preferably, the concentration of the glacial acetic acid is 60%-70%.
[0015] Preferably, in the wet etching, the etching time is 20-40 seconds and the etching temperature is 20-25°C.
[0016] Preferably, after the cleaning with the mixed solution, the independent chip is further rinsed with deionized water.
[0017] More preferably, in the mixed solution, the ratio of ammonia water, hydrogen peroxide and deionized water is 1:1:5, and the cleaning temperature is 50-60°C.
[0018] Preferably, in the drying, the drying temperature is 100-120° C. and the drying time is 1-2 hours. DETAILED DESCRIPTION
[0019] The wafer processing method of the present invention is further described below in conjunction with the embodiments, but the present invention is not limited thereby. The method of the present invention is intended to provide an improved wafer processing method, avoiding mechanical cutting, greatly reducing the stress generated when the wafer is separated, thereby reducing the deformation of the semiconductor and improving the yield rate of the product.
[0020] In one embodiment of the wafer processing method of the present invention, the following steps are included:
[0021] Protecting a first surface and a second surface of a wafer, exposing the groove on the first surface of the wafer;
[0022] Placing the first surface of the wafer in a silicon etching solution to wet-etch the groove, wherein the groove is etched to a first depth;
[0023] Placing the second surface of the wafer in a silicon etching solution to wet-etch the back side of the groove, wherein the groove is etched to a second depth, and the sum of the first depth and the second depth is suitable for separating the wafer into independent chips along the groove;
[0024] The independent chip is placed in a mixture of ammonia, hydrogen peroxide and deionized water for cleaning; and
[0025] The individual chips are dried.
[0026] The present invention first protects the wafer to expose only the groove on the first surface, etches the groove to a first depth after the first wet etching, and then etches the groove further to a second depth on the back of the groove until the wafer is separated into independent chips along the groove. The use of secondary wet etching to replace the mechanical cutting method can avoid excessive deformation caused by mechanical cutting, protect the working performance of the integrated circuit inside the chip, and ensure the yield rate. Moreover, the chips separated by wet etching are efficiently cleaned and dried, further improving the performance of the chip and extending its service life.
[0027] Specifically, before wet etching, a mask is made by exposing and developing a photoresist to leave a position for wet etching, which is the position of the groove. The first surface and the second surface of the wafer are coated with photoresist to achieve a protective effect. Preferably, the photoresist covers the side walls of the groove to protect the side walls, and only exposes the bottom wall of the groove. The object of the present invention is to deepen the bottom wall of the groove to reach a separation depth.
[0028] Specifically, the first surface of the wafer is placed in an etching tank, and the silicon etching solution is a mixture of nitric acid, glacial acetic acid and hydrofluoric acid. In a preferred embodiment, the ratio of nitric acid: glacial acetic acid: hydrofluoric acid is 7:1:1, and the concentration of glacial acetic acid is 60%-70%, such as 60%. The specific silicon etching solution can effectively corrode the groove without damaging the internal components of the wafer. Specifically, the etching time is 20-40 seconds, and the etching temperature is preferably 20-25°C. After the first wet etching, the groove is corroded to the first depth.
[0029] Then, the second surface of the wafer is placed in a silicon etching solution to perform wet etching on the back of the groove. Preferably, the silicon etching solution is a mixture of nitric acid, glacial acetic acid and hydrofluoric acid. In a preferred embodiment, the ratio of nitric acid: glacial acetic acid: hydrofluoric acid is 7:1:1, and the concentration of glacial acetic acid is 60%-70%, such as 60%. The etching time is 20-40 seconds, and the etching temperature is preferably 20-25°C. After the second wet etching, the groove is etched to a second depth, and the sum of the first depth and the second depth is suitable for separating the wafer along the groove into independent chips.
[0030] Secondary wet etching replaces mechanical cutting, and the etching time is controllable and efficient, avoiding mechanical cutting and greatly reducing the stress generated during wafer separation, thereby reducing semiconductor deformation, protecting the working performance of the integrated circuit inside the chip, and improving the product yield.
[0031] Then, after separation, the chip surface is rinsed with deionized water, and then immersed in a mixture of heated ammonia, hydrogen peroxide, and deionized water for cleaning at a temperature of 50-60° C. for 10-20 minutes. Preferably, the ratio of ammonia, hydrogen peroxide, and deionized water is 1:1:5.
[0032] Next, the chip surface is rinsed with deionized water to wash away the residues. For example, the flow rate of the deionized water is 100 psi.
[0033] Finally, the chip is dried at a temperature of 100-120°C and preferably for 1-2 hours.
[0034] Compared with the prior art, the present invention first protects the wafer and exposes only the groove on the first surface. After the first wet etching, the groove is corroded to the first depth, and then the back of the groove is wet-etched for the second time to further corrode the groove until the wafer is separated into independent chips along the groove. The use of secondary wet etching to replace the mechanical cutting method can avoid excessive stress and excessive deformation caused by mechanical cutting, protect the working performance of the integrated circuit inside the chip, and ensure the yield rate. Experiments show that this method significantly improves the deformation caused by stress on the wafer surface compared with the prior art, reducing the existing deformation height difference from 8-12μm to 0.2-2μm. Moreover, the chips separated by wet etching are efficiently cleaned and dried, which further improves the performance of the chip and extends its service life.
[0035] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope covered by the present invention.
Claims
1. A wafer processing method, characterized in that: The following steps are involved: Protecting a first surface and a second surface of a wafer, exposing the groove on the first surface of the wafer; Placing the first surface of the wafer in a silicon etching solution to wet-etch the groove, wherein the groove is etched to a first depth; Placing the second surface of the wafer in a silicon etching solution to wet-etch the back side of the groove, wherein the groove is etched to a second depth, and the sum of the first depth and the second depth is suitable for separating the wafer into independent chips along the groove; The independent chip is placed in a mixture of ammonia, hydrogen peroxide and deionized water for cleaning; and The individual chips are dried.
2. The wafer processing method according to claim 1, characterized in that: Also includes: Photoresist is coated on the first surface and the second surface of the half wafer to expose the groove.
3. The wafer processing method according to claim 2, characterized in that: Also includes: The photoresist covers the sidewalls of the groove and only exposes the bottom wall of the groove.
4. The wafer processing method according to claim 1, wherein: The silicon etching solution is a mixture of nitric acid, glacial acetic acid and hydrofluoric acid.
5. The wafer processing method according to claim 4, characterized in that: The ratio of nitric acid: glacial acetic acid: hydrofluoric acid is 7:1:
1.
6. The wafer processing method according to claim 4, characterized in that: The concentration of the glacial acetic acid is 60%-70%.
7. The wafer processing method according to claim 1, wherein: In the wet etching, the etching time is 20-40 seconds and the etching temperature is 20-25°C.
8. The wafer processing method according to claim 1, wherein: After the mixed solution is cleaned, the independent chip is rinsed with deionized water.
9. The wafer processing method according to claim 1, wherein: In the mixed solution, the ratio of ammonia water, hydrogen peroxide and deionized water is 1:1:5, and the cleaning temperature is 50-60°C.
10. The wafer processing method according to claim 1, wherein: In the drying, the drying temperature is 100-120° C. and the drying time is 1-2 hours.