Investigation of Selective Wet Etching of SiGe Substrates for High-Performance Device Manufacturing

Abstract

The use of SiGe substrate as a semiconductor material is increasing because of its unique properties. In order to manufacture high-performance devices, it is necessary to develop SiGe selective etching technology. In this study, SiGe epi and oxide substrates with varying germanium percentages (15, 25, and 40 %) were used for the investigation of the selective etching process. As the etchant, APM (1:4:20) solutions were used, and added HF and HCl to confirm the pH effect. The evaluation was conducted while adjusting the pH level. In the case of the SiGe epi substrate, the etching rate was very low at high pH, but the etching rate rapidly increased at a specific pH. And then, the etch rate gradually decreased. On the other hand, the etch rates of the oxide substrate rapidly increased as the pH decreased. To explain the etch rate behavior due to the difference in Ge content and type of substrates, the surface chemistry was measured, and the speciation of the solution was analyzed.