LASER-ASSISTED DRY-ETCHING ABLATION OF INP

An XeCI excimer laser has been used to ablate InP in a Cl-2/He environ ment. The chlorination of the surface of InP has been carried out at p ressures of the reactive gas, p, between 15 and 40 mTorr. The saturati on of the surface of the etched material with the product of reaction takes place at p>18 mTorr, and for the laser pulse repetition rates le ss than or equal to 5 Hz the removal of material at rates from 0.02 to more than 0.4 nm/pulse has been achieved. Near atomically smooth surf aces have been observed if the thickness of the removed material did n ot exceed approximately 100 nm. The diffraction and interference effec ts, which depend on the state of the polarization of the laser beam an d its coherence, have been observed to influence the surface morpholog y of material etched to depths greater than 100 nm. For linearly polar ized light the formation of surface gratings with a period of Lambda a pproximate to 0.25 mu m has been observed. Depth profiles of laser-etc hed craters indicated a strong dependence on the laser beam profile.