Low damage and selective gate recess recess etching of InAlAs/InGaAs HEMTs using fluorine and chlorine gas mixtures

A selective gate recess etching process to remove the top InGaAs cap layer from an underlying InAlAs layer is critical in the fabrication of InAlAs/InGaAs heterostructure FETs. In this study, we used mixtures of fluorine- and chlorine-based gases (CHF₃+BCl₃, CF₄+BCl₃) to realize both a high etching selectivity together with a low surface damage characteristics for gate-recessing in InP-HEMT fabrication. The etching characteristics of both mixing approaches were analyzed and compared. The DC and microwave noise characteristics of the devices were also evaluated