Wafer thinning technology

Wafer thinning process using high mesh grindstone

In the processing of the thinning of a wafer of 50μm or less, it is requested to process it with a low damage while leaving the gettering site. Although the high mesh grindstone developed by the Company can be used under the same condition as the conventional #2000 grindstone, the damage layer can be reduced to 0.5μm or less.
Further, the pad of the fixed abrasive type is installed in the conventional polish head, which enables further development to increase the chip strength while creating the gettering site as well.
Along with the progress in the thinning of the wafers, there is an increase in their stock removal by one axis processing, thus helping to affect the throughput. Therefore, a high-efficient grinding wheel with one axis which can process at double the speed of a conventional processing has been developed. This grindstone can be effective in the chipping control by one axis processing as well, and reduce the amount of the outer chipping to 10μm or less.

Measures to reduce the outer chipping

Outer chipping of the wafer is directly related to crack, and is caused by one axis coarse grinding process. A big chipping can be reduced by one-axis grindstone or optimization of processing conditions. Moreover, due to the thinning of the wafer, the cross section of wafer edge condition is more prone to chipping and knife-edge. Chipping due to the sharp edge can be prevented from occurring by trimming the wafer edge beforehand. Our grinder carries out fully automatic edge trimming.

Stress relief by scanning polish