Michaelis–Menten kinetics during dry etching processes

Abstract

The chemical etching of germanium in Br2 environment at elevated temperatures is described by the Michaelis–Menten equation. The validity limit of Michaelis–Menten kinetics is subjected to the detailed analysis. The steady-state etching rate requires synergy of two different process parameters. High purity gas should be directed to the substrate on which intermediate reaction product does not accumulate. Theoretical calculations indicate that maximum etching rate is maintained when 99.89% of the germanium surface is covered by the reaction product, and 99.9999967% of the incident Br2 molecules are reflected from the substrate surface. Under these conditions, single GeBr2 molecule is formed after 30 million collisions of Br2 molecules with the germanium surface.

Summary

Knizikevičius's study applies Michaelis–Menten kinetics to the chemical etching of germanium in a Br₂ environment at elevated temperatures. The research analyzes the validity of this application, emphasizing the need for the synergy of two different process parameters to achieve the steady-state etching rate. Theoretical calculations suggest that maintaining the maximum etching rate requires specific conditions, including a high coverage of the germanium surface by the reaction product and a significant reflection of incident Br₂ molecules from the substrate surface.