Investigation of the Defect Distribution of Laser Contact Opening Applied to Poly-Si/SiNx Stacks

Herein, an analysis on the impact of laser contact opening of TOPCon/SiNx stacks is presented. By etching in tetramethylammonium hydroxide (TMAH), the defect distribution in the interfacial tunnel oxide is accessed and analyzed. The defect density is significantly increased in areas where adjacent laser contact openings (LCO) overlap. Using microscopic photoluminescence (mu-PL) spectroscopy, it is verified that correlates with an increase in the local recombination rate and thus an increase in the J(0,Met). Therefore, overlapping LCO of SiNx in TOPCon/SiNx stacks should be avoided as much as possible. Furthermore, the investigations indicate that defects in the interfacial oxide are dominantly created along exposed structures like tips and edges of (etched-back) pyramids. A comparison of TOPCon/SiNx stacks with a variation of TOPCon thicknesses indicate that etch pits, and thus the defect density, related to LCO become more significant at lower thicknesses.

Automated summary

This study presents an analysis on the impact of laser contact opening of TOPCon/SiNx stacks. By etching in tetramethylammonium hydroxide (TMAH), the defect distribution in the interfacial tunnel oxide is accessed and analyzed. The findings show that the defect density significantly increases in areas where adjacent laser contact openings overlap. Furthermore, the investigations reveal that defects in the interfacial oxide are mainly created along exposed structures like tips and edges of (etched-back) pyramids. Comparison of TOPCon/SiNx stacks with different TOPCon thicknesses also indicates that etch pits and defect density related to laser contact opening become more significant at lower thicknesses.