Shallow junction formation by phosphorus diffusion from in situ spike-doped chemical vapor deposited amorphous silicon

Abstract

Shallow and lateral homogeneous delineated n +p-junctions were formed by utilizing solid source diffusion from a deposited amorphous silicon layer with an in situ imbedded P rich zone. After heat treatment the layer remains flat, surface roughness has found to be less than 3nm. Dopant pile up at the Si-layer/Si-substrate interface has been observed and interpreted based on segregation phenomena. From the time dependence the P segregation pile up has found to be diffusion limited except of a small starting period. The dopant concentration in the Si-substrate drops down over more than 2 orders of magnitude in a thickness range less than 20 nm.