EFFECTIVE PASSIVATION OF THE LOW-RESISTIVITY SILICON SURFACE BY A RAPID THERMAL OXIDE PLASMA SILICON-NITRIDE STACK

A passivation scheme involving plasma silicon nitride (PECVD SiN) depo sition on top of SiO2 grown by rapid thermal oxidation is developed to attain a low surface recombination velocity (S) of nearly 10 cm/s on the 1.25 Omega cm p-type (100) silicon surface. Such low S values are achieved by the stack structure even when the rapid thermal oxide (RTO ) or PECVD SIN films individually yield poorer surface passivation. Cr itical to achieving low S by the RTO/PECVD SN stack is the use of a sh ort, moderate temperature anneal (in this st;dy 730 degrees C for 30 s econds) after the stack formation. This thermal treatment is believed to enhance the release and delivery of atomic hydrogen from the SiN fi lm to the Si-SiO2 interface, thereby reducing the density of interface traps at the silicon surface. Compatibility with this post-deposition anneal makes the stack passivation scheme attractive for cost-effecti ve solar cell. production where a similar anneal is required to form s creen-printed contacts. (C) 1998 American Institute of Physics.