Reaction mechanism for fluorine etching of silicon.

Abstract

A reaction mechanism is proposed for etching of Si surfaces by F atoms in which ${\mathrm{SiF}}_{4}$ is formed. We proposed that in the rate-determining step the F atom attacks the back side of a ---${\mathrm{SiF}}_{3}$ moiety with simultaneous Si---F bond formation and Si---Si bond rupture (as in an ${S}_{N}$2 process). The transition state for this process involves charge transfer from the rupturing Si---Si bond to the attacking F atom and is consistent with recent observations that the etch rate is greater for n-type than for p-type silicon.

Group Members

William A. Goddard III

Charles and Mary Ferkel Professor