Chemical Mechanical Polishing of Epitaxial Germanium on SiO2-patterned Si(001) Substrates

Abstract

Aspect Ratio Trapping is a promising technique for heterointegration of Ge onto Si substrates. By growing Ge in patterned SiO2 trenches, lattice-mismatch dislocations arising from the epitaxial interface can be effectively trapped. However, planarization of these samples is required to enable device fabrication. This paper describes the development and optimization of a chemical mechanical polishing process for these structures. Polishing using diluted Nalco 2360 slurry was investigated, with the addition of NaOCl, NH4OH, or H2O2, for Ge removal rate increase. A slurry mix consisting of Nalco 2360, H2O2, and DI water was shown to have low dishing and low surface metals contamination, and planarized the Ge Aspect Ratio Trapping samples very effectively.