Reactive Ion Etching of Tungsten Films Sputter Deposited on GaAs

A correlation between reactive ion etching (RIE) characteristics of W films and their microstructural features has been investigated, and it was found that the α‐phase W can be controllably etched compared with the α+β mixed modification. The etch rate for the stable, α‐phase W films with and plasmas has been shown to depend strongly on the discharge parameters—RF power and reactor pressure. Effects of the Ar, , and additions and the etching selectivity between the W film and photoresist (Shipley AZ‐1350) have also been studied in detail. These observations have led to the conclusion that the mixed system is mostly attractive for a variety of device processing applications. The chemical nature of the RIE‐processed W surface has been examined by secondary ion mass spectrometry, and an apparent presence of C, O, F, and S species on the surface has been confirmed. By I‐V and C‐V measurements of Schottky contacts fabricated on RIE‐processed surface, no indication of damage layers has been detected.