CL-2-BASED DRY-ETCHING OF GAAS, ALGAAS, AND GAP

Cl-2-based plasmas for etching GaAs, AlGaAs, and GaP have been examine d as a function of gas additive (Ar, N-2, or H-2), radio frequency (RF ) and microwave power, plasma composition, mask material, and process pressure. In a load-locked reactor, smooth etched surface morphologies were obtained over basically all conditions investigated, with typica l root-mean-square roughness of less than or equal to 1.5 nm measured by atomic force microscopy. The etch rates for all three materials inc rease with RF power (ion energy), microwave power (ion current), Cl-2 percentage, and pressure, with controlled rates of similar to 0.4 mu m /min at a condition of 2Cl(2)/13Ar, 850 W microwave power, 1.5 mTorr, and 100 to 150 W of RF power. Operating under electron cyclotron reson ance conditions where the ion density is greater than or equal to 5 x 10(11) cm(-3) (measured by microwave reflection interferometry) produc es rapid degradation of photoresist, and more robust mask materials su ch as SiNX, SiO2, or W are necessary.