Wafer thinning method

Abstract

The invention discloses a wafer thinning method. The wafer thinning method is characterized by comprising the steps of providing a wafer to be thinned, trimming a wafer edge by laser, and removing a part of material at a round angle to form an arc chamfer angle; preparing a coating liquid, uniformly coating the coating liquid on a front surface of the wafer and the chamfer angle of the edge, baking and hardening to form a coverage layer, and fixing the front surface of the wafer and a substrate; performing first-time grinding on a back surface of the wafer, and performing first-time wet etching on the back surface of the wafer; performing second-time grinding on the back surface of the wafer; and performing second-time wet etching on the back surface of the wafer, making the wafer and thesubstrate separated, removing the coverage layer of the wafer, thereby obtaining the thinned wafer. The wafer thinning method employs a special protection process, the internal stress of the device generated during the wafer thinning process can be reduced, the front surface of the wafer can be prevented from being polluted by a mixture of particle generated during the wafer thinning process and cooling wafer, the breakage probability is reduced, the finished rate is improved, and the production cost is reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a wafer thinning method. Background technique [0002] In the chip manufacturing process of semiconductor devices, in order to improve efficiency, the size of the wafer used to manufacture the chip is getting larger and larger. In order not to reduce the strength, the thickness of the wafer is also continuously thickened with the increase in size. On the other hand, the thickness requirements of the package for the chip have not changed. In particular, when the chip size is smaller than 0.5mm and further reduced, the thickness of the chip will increase significantly relative to the length and width, and the chip is more like a cube or a cylinder. The form factor will seriously affect the package. In this case, it is necessary to perform ultra-thick thinning of the wafer after the chip manufacturing process is basically completed. [0003] The existing device wafer thinni...

AI Technical Summary

Problems solved by technology

[0003] The existing device wafer thinning methods are generally grinding and wet etching. The grinding thinning speed is fast and has a good effect on improving production capacity. However, grinding is easy to cause wafer cracks, increase internal stress, and the difference in surface thickness is obvious, so it will It is easy to cause wafer fragmentation in the subsequent process

Wet etching thinning can relieve the internal stress caused by grinding, and can make the surface have better thickness uniformity, but the thinning rate is slow

At present, the commonly used process for thinning device wafers is to perform one grinding after bonding the device wafer to the carrier, and then perform multiple wet etching. Although this process method utilizes wet etching to a certain extent However, due to the excessive thickness of the grinding, the generated internal stress is correspondingly too large, and device wafer fragments will still occur during the thinning process, which will affect the device wafer yield and cause cost loss