GaAs etch rate enhancement with SF6 addition to BCl3 plasmas

A dramatic increase in the GaAs etch rate has been observed with the additi on of SF6 to BCl3 plasmas. The etch rate increases from 70 Angstrom/min in pure BCl3 to 4000 Angstrom/min with 70% SF6 in the total flow. Optical emis sion intensities of both molecular and atomic chlorine were observed to inc rease with SF6 addition, and the peak intensity of the atomic chlorine emis sion coincided with the peak in the etch rate. Argon was added to the mixtu re as an actinometer, and the argon emission intensity at 750 nm increased significantly with the addition of SF6. However, microwave measurements ind icated that the average electron density decreases with increasing SF6 addi tion. It is believed that the increased production of etch species is due t o an increase in the average electron temperature as a result of electron a ttachment heating. (C) 2000 The Electrochemical Society. S0013-4651(99)12-0 83-4. All rights reserved.