IMPURITY GETTERING BY PHOSPHOROUS DOPING IN SILICON WAFERS

Abstract

In this project, the effect of phosphorous gettering with inline diffusion furnace was studied. Experiments were performed on normal grade A1 wafers as well as a block of laser-marked wafers. The result of the experiment with A1 wafers showed a 0.05% drop in efficiency. However, gains were seen for Isc and Voc and the number of low efficiency cells had reduced significantly. From the experiment with laser-marked wafers, it was observed that only the bottom 40 wafers from a block had benefited from the gettering process with a 0.2% efficiency gain, while the other wafers had slight efficiency degradation. The observed trend can be explain by the iron impurity level and dislocation level in wafers of different vertical positions in a block.