Microwave enhanced silicon KOH etching

Abstract

A microwave source system have been used to increase silicon etch rate in KOH solution by a factor of about 2, when compared to conventional process. In this work, using a commercial microwave oven (operated at 850W), a home-made microwave system and a polytetrafluoroethylene (PTFE) reactor, where the silicon etching is processed with KOH-water solution, were developed. Silicon wafers, previously oxidized and patterned with standard photo-lithographic process, were etched using 2.5, 5 and 10 M KOH-water solution. The process temperature was manually controlled. The etch solution passes through a heat exchanger for cooling purpose and is pumped back to the reactor. Etch rate of about 1.38 μm/min for the [100] silicon crystal plane and 2.7 nm/min for thermal silicon oxide was achieved.