Electronic Quality Improvement of Highly Defective Quasi-Mono Silicon Material by Phosphorus Diffusion Gettering

Quasi-mono silicon (QM-Si) attracts interest as a substrate material for silicon device processing with the promise to yield single-crystalline silicon quality with multicrystalline silicon cost. A significant barrier to widespread implementation of QM-Si is ingot edge-contamination caused by the seed material and crucible walls during crystal growth. This work aims to recover the scrap material in QM-Si manufacturing with a process easily adaptable to semiconductor device manufacturing. A phosphorus diffusion process at 870 °C for 60 min significantly improves the electronic quality of a QM-Si wafer cut from a contaminated edge brick. The harmonic minority carrier recombination lifetime of the wafer, a key predictor of ultimate device performance, experiences a tenfold increase from 17 to 178 μs, which makes the scrap QM-Si material usable for device fabrication. Local areas with suboptimal (<50 μs) lifetimes remaining can be further improved by a high temperature anneal before the phosphorus diffusion process.