In order to find out which metals cause s-pits in silicon epitaxial layers in ordinary production conditions

some of the pure metals

such as Fe

Cr

Cu

Au

and aqueous solutions of FeCl3

CuCl2 and NaCl were used for intentional contamination. The samples were <111>rientation

CZ dislocation-free silicon single crystal wafers. After such contamination

a hydrogen heat treatment or an epitaxy process was carried on at about 1200℃. It was observed that the contamination of Fe or FeCl3 always produced s-pits defects

and the same with Cr. But when the substrates were contaminated by Cu

Au

or NaCl

CuCl2

no s-pits were observed.Metals which cause s-pits in silicon epitaxial layers will produce the same defects in single crystal substrates.