Tantalum‐Based Encapsulants For Thermal Annealing of GaAs

Abstract

During thermal annealing of there is a tendency for arsenic to evaporate. This process can have deleterious consequences and must be controlled during annealing by encapsulants. We survey conducting electrically, sputtered tantalum‐based encapsulants as capping materials for thermal annealing of in the temperature range 550–900°C. Conducting capping layers have the advantage that they can be integrated in a contact metallization scheme. The backscattering spectrometry results show that Ta is not an effective cap. Evaporation through can be detected after annealing at 700°C. Amorphous was a good cap up to 800°C, and amorphous up to 850°C. Thus, while the effectiveness of Ta‐based caps was improved significantly by the addition of either nitrogen or silicon alone, the best results were obtained for caps containing both Si and N.