Magnetized inductively coupled plasma etching of GaN in Cl-2/BCl3 plasmas

In this study, Cl-2/BCl3 magnetized inductively coupled plasmas were used t o etch GaN, and the effects of magnetic confinements of inductively coupled plasmas on the GaN etch characteristics were investigated as a function of Cl-2/BCl3. Also, the effects of Kr addition to the magnetized Cl-2/BCl3 pl asmas on the GaN etch rates were investigated. The characteristics of the p lasmas were estimated using a Langmuir probe and quadrupole mass spectromet ry (QMS). Etched GaN profiles were observed using scanning electron microsc opy. The small addition of BCl3 (10%-20%) in Cl-2 increased the GaN etch ra tes for plasmas both with and without magnetic confinements. The applicatio n of magnetic confinements to the Cl-2/BCl3 inductively coupled plasmas inc reased the GaN etch rates and changed the Cl-2/BCl3 gas composition of the peak GaN etch rate from 10% BCl3 to 20% BCl3. It also increased the etch se lectivity over the photoresist, while slightly reducing the selectivity ove r SiO2. The application of the magnetic field significantly increased posit ive BCl2+ measured by QMS and total ion saturation current measured by the Langmuir probe. Other species such as Cl, BCl, and Cl+ increased, whereas s pecies such as BCl2 and BCl3 decreased with the application of the magnetic field. Therefore, it appears that the increase of the GaN etch rate in our experiment is related to the increased dissociative ionization of BCl3 by the application of the ;magnetic field. The addition of 10% Kr in an optimi zed Cl-2/BCl3 condition (80% Cl-2/20% BCl3) with the magnets increased the GaN etch rate about 60%. A more anisotropic GaN etch profile was obtained w ith the application of the magnetic field, and a vertical GaN etch profile was obtained with the addition of 10% Kr in an optimized Cl-2/BCl3 conditio n with the magnets. (C) 2000 American Vacuum Society. [S0734-2101(00)16404- 8].