Characterization of Thin Films and Critical Dimensions in Silicon Carbide and Gallium Nitride Process Flows

Abstract

As Silicon Carbide (SiC) and Gallium Nitride (GaN) devices go into full high-volume-manufacturing (HVM), process control becomes ever more necessary to maximize device yield across the wafer. This includes on-wafer metrology and inspection, data from which can be fed back and, in some cases, fed forward for equipment control. This paper will focus on key challenges in SiC and GaN device processing. Thin film characterization – thickness, uniformity, multi-layer epitaxy, dopant concentration – is a key requirement to monitor and control process tools. This is especially important for GaN where multiple buffer layers must be deposited, and hence monitored on a silicon or SiC handle wafer. (Add PL for Al conc.) Similarly, metal films characterization is required to prevent surface defects that can cause increased contact resistance. SiC devices are shifting from planar to trench architectures. All such devices will require critical dimension (CD) control for top/bottom of a trench. Simultaneously, overlay metrology for lithography becomes more relevant as process steps increase in complexity. Finally, this presentation will show enterprise software can be used to feedback or feed forward on-wafer results to more effectively control process tools.