Dry etching of Combined Gallium Nitride Epitaxial Layer and Silicon Carbide Substrate

Statement of work Dry etching of Combined Gallium Nitride Epitaxial Layer and Silicon Carbide Substrate (See illustrative cross section below) Vendor:  Shall fabricate one 3” and approximately 350 microns thick single crystal 4H-SiC wafer. Wafer is already electroplated with patterned nickel etch mask to facilitate the etching process.  Shall etch wafer to 280 microns to a diaphragm having approximate thickness of 70 microns. Diaphragm radii range from 300 microns to 900 microns.  Shall use reasonable effort to obtain a smooth diaphragm with fewer than 5 micro mask artifacts on each etched diaphragm surface.  Shall achieve diaphragm thickness uniformity across the 3” wafer of ±5% of the 70- micron thickness.  Shall achieve diaphragm features that are smooth and free of “scallops.”  The intersection of the diaphragm base with the sidewall shall have a reasonable radius but shall not be notched.  Edge-wall trenching artifacts at the intersection of the diaphragm base and the sidewall shall not be accepted.  The aspect ratio (etched depth/etched width) shall be no less than 5. Higher aspect ratio will be preferred.  The etch recipe shall be determined by the foundry.  Shall dry-etch the top side p-GaN to 3 μm (SiO2 etch mask provide) to exposed 4H-SiC surface.  Shall confirm etched depth to be 3 microns.  Confirm etched depth. -- 1 of 1 --