Electron cyclotron resonance etching characteristics of GaN in plasmas with and without hydrogen

Abstract

Electron cyclotron resonance (ECR) plasma etching characteristics of gallium nitride (GaN) are investigated using low pressure (4-10 mTorr) SiCl4/Ar and Cl2/H2/Ar ECR discharges. The purpose of this effort is to develop a dry etching process for making laser mirrors on GaN and to examine dry etching processes of GaN that do not require hydrogen, which is known to cause carrier compensation in GaN. The etch rate is found to increase near-linearly with increasing DC bias, and a minimum DC bias of 100V is required to initiate etching in SiCl4/Ar. We have also found that the material quality significantly affects the etch rate. The latter decreases with x-ray rocking curve half-width and increases with defect density. A reasonable etch rate of 660Ǻ/min and good surface morphologies obtained in SiCl/Ar ECR etching make this process suitable for gate recess of an FET. An etch rate of 5270Ǻ/min has been achieved in Cl2/H2/Ar plasmas. This is the highest reported etch rate of GaN so far. The smooth and vertical etch sidewalls (etch to mask selectivity of 16 is obtained) make this process promising for dry-etched laser mirrors on GaN.

Inductively Coupled Plasma Etching of III‐V Nitrides in CH 4 / H 2 / Ar and CH 4 / H 2 / N 2 Chemistries

“…The basic trend is that the surfaces are smoother at lower ion energy conditions. Figure 8 shows the raw AFM data for GaN as-grown and after etch as a function of ICP power in CH,/H,/Ar plasmas.…”

Magnetized inductively coupled plasma etching of GaN in Cl2/BCl3 plasmas

“…[1][2][3][4] In the case of GaN-based optoelectronic devices, fabricating the devices successfully requires reproducible etching processes with high etch rate, vertical, and smooth etch profile. [7][8][9][10][11][12][13][14][15][16] The application of a magnetic field to inductively coupled plasmas is known to further increase plasma densities, but also to increase the plasma uniformity if adequate combinations of permanent magnetic cusping and Helmholtz-type axial magnets are used. [7][8][9][10][11][12][13][14][15][16] The application of a magnetic field to inductively coupled plasmas is known to further increase plasma densities, but also to increase the plasma uniformity if adequate combinations of permanent magnetic cusping and Helmholtz-type axial magnets are used.…”