Study of diffusion barriers for Au metal on liquid phase oxidized GaAs

Abstract

TiW, TiN, Pd, and Mo as the diffusion barriers (DBs) in Au/DB/GaAs native oxide multilayer structures are investigated. The GaAs native oxides are prepared by liquid phase oxidation, and the results indicate that TiW and Mo films can effectively block Au diffusion at temperatures of up to 550°C for 30min. However, TiN and Pd films can effectively block Au diffusion only at 450°C for 30min. The failure of TiN and Pd appears related to the embedded oxygen in the barrier layers which cause the interdiffusion between Au and the barrier films. In comparison, TiW and Mo show better blocking properties that prevent Au from diffusing into oxide films. They also act as a diffusion barrier even at temperatures above 550°C.