Low temperature diffusion process for dopant concentration enhancement

摘要

Doped semiconductor with high dopant concentrations in small semiconductor regions without excess spreading of the doped region are formed by: (a) applying a dopant-containing oxide glass layer (60) on the semiconductor surface (61), (b) capping the dopant-containing oxide glass layer with a conformal silicon oxide layer (62), (c) heating the substrate from step (b) in a non-oxidizing atmosphere whereby at least a portion of the dopant in the glass diffuses into the substrate at the semiconductor surface, and (d) heating the glass-coated substrate from step (c) in an oxidizing atmosphere whereby at least a portion of the dopant in the glass near the semiconductor surface is forced into the substrate at the semiconductor surface by diffusion of oxygen through the glass. The method is especially useful for making buried plates in semiconductor substrates which may be used in trench capacitor structures. The preferred semiconductor substrate material is monocrystalline silicon. The preferred dopant is arsenic.