Reactive ion etching (RIE) and photo-assisted RIE processes are being developed for these materials. BN dry etching was found optimum in Cl2/Ar at 40 mTorr with and without irradiation. The standard and photo-assisted RIE etch rates increased with dc self-bias, up to 1020 and 2200 Å/min at -400 V dc bias, respectively. GaN was found to etch better in BCl3/Cl2/N2 at 30 mTorr, reaching 3240 at -470 V dc bias under a filtered Xe lamp beam. Smoother and cleaner etched surfaces resulted when the photo-assisted RIE process was used instead of the standard process. This work is currently being extended to the AlGaN and InGaN ternaries.

As a backup and a complement to the dry etching techniques, we are developing a photoelectrochemical (PEC) wet etch process which utilizes photogenerated electron-hole pairs to enhance oxidation and reduction reactions taking place in an electrochemical cell. While promising results have been obtained, many refinements need to be realized for this technique to become mature.

A unique miniature time of flight mass spectrometer is being evaluated for real time plasma etch monitoring in collaboration with Ionwerks, a local high technology company. The mass spectrometer, which employs orthogonal extraction, has a resolving power m/Dm in excess of 500 and a detection limit of 10 ppm for all masses at a one second sampling rate. In addition, optical emission spectroscopy (OES) identification of species in the plasma is also being implemented.