Characterization of AlGaN/GaN degradations during plasma etching for power devices

During the fabrication of a MOS-HEMT, the plasma-etching steps are critical because they can damage the GaN materials and lead to electrical degradation effects. To address these limitations, we studied the influence of plasma parameters on electrical degradation in an AlGaN/GaN heterostructure. In this work, the modifications induced by bias-voltage applied during the SiN capping layer opening are investigated. Physical (XRD, XRR, AFM and TEM) and chemical (XPS) characterizations have been performed to have a better understanding this plasma parameter on GaN damage. These results are correlated with Rsheet measurements to evaluate the electrical degradation in the heterostructure. Finally, degradation mechanisms and recommendation have been proposed to improve the plasma etching process.