Title :
A selective dry-etch technique for GaAs MESFET gate recessing
Author :
Chang, Edward Y. ; Van Hove, James M. ; Pande, Krishna P.
Author_Institution :
Unisys Corp., St. Paul, MN, USA
fDate :
10/1/1988 12:00:00 AM
Abstract :
Reports a selective dry-etching technique for GaAs MESFET gate recessing, where a thin AlGaAs etch stop is used to precisely control the recess depth. Selective dry etching was achieved by using a CCl2F2/He gas mixture yielding a selectivity of >600 for GaAs over AlGaAs. A thin (35-50-Å) AlxGa 1-xAs layer (x=0.3) was used to control the etch depth. The surface composition of the RIE (reactive ion etch) recessed AlGaAs layers was analyzed by angle-resolved X-ray photospectrometry and compared to the surface compositions of the wet-chemically recessed samples. The standard deviation of MESFET threshold voltage was as low as 20 mV across a 3-in. wafer by using this selective dry-etch technique. The MESFETs show excellent electrical characteristics with transconductance of 150 mS/mm for a 1×100 μm gate and breakdown voltages as high as 38 V
Keywords :
III-V semiconductors; Schottky gate field effect transistors; X-ray spectroscopy; gallium arsenide; sputter etching; 20 mV; AlxGa1-xAs layer; CCl2F2-He; GaAs; MESFET gate recessing; RIE; angle-resolved X-ray photospectrometry; breakdown voltages; electrical characteristics; etch stop; recess depth; selective dry-etch technique; selectivity; surface composition; threshold voltage; transconductance; Chemical processes; Dry etching; Gallium arsenide; Helium; MESFETs; Surface cleaning; Surface morphology; Surface treatment; Threshold voltage; Wet etching;
Journal_Title :
Electron Devices, IEEE Transactions on