The Investigation on Fast and Uniform Diffusion for Silicon Solar Cell Production

Diffusion tubes are used in normal production process. It can provide a high minority carrier lifetime. But it is determined by the cleanliness of the tubes. Trace amount of impurity in the tubes will strongly influence the lifetime. Additionally, the phosphorous source, POCl3 is a highly toxic and corrosive chemical, which needs a high cost to manage. In this paper, a fast and uniform diffusion process used for solar cell production is investigated. A kind of nontoxic and low corrosive phosphorous source is sprayed on the surface of silicon wafers. And then the wafers are transported inline into a high temperature nitrogen atmosphere by an alloy belt. After this inline diffusion, the unevenness of sheet resistance can be decreased to below 5%, the efficiency of the cells using inline diffusion is a little higher than that of the cells diffused in tubes which may be attribute to the excellent uniformity.