STUDY AND APPLICATION OF REACTIVE ION ETCHING ON GAINP INGAAS/GAINP QUANTUM-WELL HEMTS/

The gate recessing of a GaInP/InGaAs/GaInP quantum-weil HEMT (QHEMT) u sing pure BCl3 plasma is found improved by the addition of an appropri ate amount of Ar to the gas flow. The influence of BCl3/Ar gas flow ra tio on GaAs to GaInP etch selectivity, surface roughness and surface d amage was determined. These results indicate that the conditions for m inimum surface roughness, as determined by atomic force microscopy, co rresponded with the conditions for minimum plasma damage. as determine by Raman spectroscopy. The best BCl3/Ar gas flow ratio for minimum su rface damage and roughness was found to be 6:4 at a pressure of 60 mTo rr with a 100 W RF power at this study. Two BCl3:Ar flow rate ratios, 6:4 and 10:0 (pure BCl3) were used to etch the gate recess in GaInP/In GaAs/GaInP QHEMT. From C-T measurements, it is found that the plasma-i nduced damage of the sample S-6:4 dry-etch with 6:4 BCl3/Ar is less th an that of the sample S-10:0 dry-etched with pure BCl3. The d.c. chara cteristics of S-6:4 device was found to be superior to those of the we t-etched sample S-wet and S-10:0. In addition, the threshold voltage u niformity of sample SG:4 was found to be better than that of sample S- wet and sample S-10:0. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.