In-situ plasma cleaning of stainless steel III-V MOCVD growth systems

Abstract

A plasma enhanced, in-situ, dry etching process for the cleaning of stainless steel III-V Metal Organic Chemical Vapor Deposition growth systems was investigated as a function of etchant gas, flow rate, electrode configuration, power density and plasma frequency. The plasma enhanced etching process was investigated using Ar, CH4 (5% in H2), CCl2F2 (Freon 12)/Ar and Cl2/Ar plasmas with flows varying from 5 to 25 seem. The plasma was excited using three electrode configurations, and two radio frequency generators (90–460 KHz and 13.56 MHz), singly and in combination. The plasma power was varied over the range from 200 to 700 Watts (∼0.2W/cm2 – 0.7W/cm2). The etching rates of GaAs, InP, As, and Mo were measured using a weight difference method. The Cl2/Ar plasmas exhibited etching rates typically 5 to 10 times greater than that of CCl2F2 plasmas, which in turn is several times greater than that of the other etchant gases investigated. At 400 W, elemental As etch rates, as high as ∼180μm/hr and ∼20μm/hr were achieved using Cl2 and CCl2F2 plasmas, respectively. InP/GaAs etch rates using Cl2 were ∼30μm/hr and using CCl2F2 were ∼7μm/hr. Plasma characteristics and etch rate measurements are reported. The in-situ process investigated is a safe, cost effective and an efficient method for increasing reactor uptime.