Reactive ion etching of boron nitride and gallium nitride materials in Cl_2/Ar and BCl_3/Cl_2/Ar chemistries

摘要

Boron nitride (BN) and gallium nitride (GaN) are known as superior semiconductor materials for high power and high temeprature applications. Undoped BN layers grown using ion beam and electron cyclotron resonance (ECR) assisted physical deposition on conductive GaN films have demonstrated good insulating properties. These films are thus good candidates as thin insulating layers in high temperature GaN-based device structures such as MIS diodes and MISFETs due to their close thermal expansion coefficient. In order to address the device processing issue, reactive ion etching (RIE) tests were performed on these films. Using Cl_2/Ar chemistry, etch rates up to 600 A/min were measured. These rates were found to increase linearly with increasing rf power and Cl_2 flow rate. GaN layers grown by gas source MBE were also dry etched, resulting in smooth sidewalls. Etch layers grown by gas source MBE were also dry etched, resulting in smooth sidewalls. Etch rates up to 1,400 A/min were achieved at 200 W rf power (-230 V d.c. bias) in a BCl_c/Cl_2/Ar for BN and GaN respectively, etch selectivities in excess of 5:1 can be obtained. Finally, preliminary Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) results on residue deposition and surface composition changes as a function of the different etch conditions are presented.