Monolayer control of chemical beam etching

Abstract

An etching process with real-time monitoring of each monolayer removed is demonstrated. This etching capability which we refer to as monolayer chemical beam etching (ML-CBET) is achieved by employing in-situ reflection high energy electron diffraction (RHEED) intensity oscillation monitoring during etch. The etching is accomplished by injecting AsCl 3 or PCl 3 gas directly into the growth chamber at a temperature comparable to the typical growth temperature in the same system. This permits instant switching from etching to growth and vice versa in the same experimental run. The combination of growth and etch in a single chamber with both controllable at atomic scale presents a very powerful processing method for the fabrication of intergrated devices that require multiple steps of etch and regrowth. We have also identified the roughening mechanism during etch and present the methods to obtain excellent morphology through a migration enhanced smoothing mechanism.