Stress Concentration Reduction at Crack Tip by Adding Nanonotches on Chip Surface

Increasing uses of silicon chip in solar cell makes the thinning of silicon chip necessary. Surface defects are easily induced on chip during the thinning and machining processes. The stress concentration resulted from defects would be the source of crack and failure of silicon chips. In this research, the finite element analysis was used to investigate the effect of nanonotches on stress concentration caused by surface defect with different parameters for silicon chip. Since we focused on the stress distribution near the defect, nanonotches were introduced in the nearby area of defect in the finite element analysis. The silicon chip was under four-point bending and the stress concentration factor at crack tip on silicon chip with nanonotches was reduced more than 40% for the case studied.