For a single crystal wafer, due to its inherent brittleness, the surface roughness is regarded as the most critical factor in determining the strength of the chip. After a grinding process is applied to the back side, grinding traces can be left on the wafer, depending on the grinding mode. This paper is intended to evaluate the effects of grinding marks on the bending strength of chips quantitatively when the grinding marks are generated by back grinding during the course of the silicon wafer thinning process. To that end, chips were taken from wafers under different grinding conditions and the bending strength of each was then measured, depending on the direction of the bending axis and on the grinding marks. Using the AFM, surface roughness was measured in each grinding condition. In addition, after the bending strength test, the fracture behavior depending on each bending condition was analyzed. In conclusion, when polishing using grit that was less fine than number- 2000 grit, the bending strengths of thinned chips were strikingly different depending on the location on the wafer. However, the chips precisely polished had a greater strength than the chips that were ground.

Keywords: Roughness, Bending Strength, Silicon wafer