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.
Dr. Srivastava joined Onto Innovation in June 2022 as Director, Strategic Marketing where he manages metrology and inspection strategy for substrates and compound semiconductor devices. He has over 25 years’ experience in the semiconductor industry, and prior to joining Onto Innovation he worked at Applied Materials in the ion implant division. Dr. Srivastava has published over 30 papers in peer-reviewed journals and holds over a dozen patents and trade secrets. He is a member of the American Vacuum Society and the Institute of Electrical and Electronics Engineers.