Optical emission end point detection for reactive ion etching of Si/SiGe structures

Abstract

Reactive ion etching of epitaxial Si 1−x Ge x (0.1 ⩽ × ⩽ 0.33)) using a Cl 2/SiCl 4/N 2 discharge has been studied. Optical emission monitoring of the 265. 1 nm Ge line during SiGe etching provided a sensitive and accurate indicator for end point detection. The realization of defined etch stops in a 30 nm thick buried Si 0.78Ge 0.22 layer on an underlying Si substrate during dry etching of Si/SiGe/Si heterostructures for technological applications was demonstrated. The etch rate of the SiGe film has found to increase with the Ge content. A good correlation of the 265 nm emission line intensity of Ge to the SiGe etch rate was observed. Optical emission end point detection can overcome the lack of Si/SiGe selectivity.