Dry Etching Of High Aspect Ratio 4h-Sic Microstructures

Deep reactive-ion etching (DRIE) of high aspect ratio structures in 4H-SiC is demonstrated. Electroplated nickel is used as the etch mask and patterned with openings ranging from 2-10 mu m. Etch depths of 51 to 57 mu m are obtained after a 2 hour reactive ion etch with SF6/O-2 inductively coupled plasma for 2-6 mu m mask openings. Thus, aspect ratios (depth: mask opening) of 25.5 to 9.5 are achieved. Sidewall morphology is shown as a function of helium back side cooling with close to vertical sidewalls obtained with less cooling. (c) 2017 The Electrochemical Society. All rights reserved.