Quasi-atomic layer etching of silicon with surface chlorination and removal using Ar or He plasmas

A comparative study of argon (Ar) and helium (He) plasmas is conducted in quasi-atomic layer etching (ALE) processes for silicon (Si). The ALE window is identified to be between 35 and 55 V for Ar and 25-45 V for He, with an etch per cycle of 6.0 angstrom/cycle for Ar and 7.5 angstrom/cycle for He. Thirty percent thicker chlorination layers are observed with Cl2/He ALE than with Cl2/Ar ALE in the chlorination step. The penetration depth of He ions is twice that of Ar ions, with a standard deviation of 4.5 times greater. This study demonstrates that He ions in the removal steps considerably affect the subsequent modification steps in Si ALE. A comparative study was conducted on argon (Ar) and helium (He) plasmas in quasi-atomic layer etching (ALE) processes for silicon (Si). The study demonstrates that He ions in the removal steps can significantly influence the subsequent modification steps in Si ALE processes. image