Laser-assisted dry etching ablation of InP

An XeCl excimer laser has been used to ablate InP in a Cl2/He environment. The chlorination of the surface of InP has been carried out at pressures of the reactive gas, p, between 15 and 40 mTorr. The saturation 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 ≤ 5 Hz the removal of material at rates from 0.02 to more than 0.4 nm/pulse has been achieved. Near atomically smooth surfaces have been observed if the thickness of the removed material did not exceed approximately 100 nm. The diffraction and interference effects, which depend on the state of the polarization of the laser beam and its coherence, have been observed to influence the surface morphology of material etched to depths greater than 100 nm. For linearly polarized light the formation of surface gratings with a period of Λ ≈ 0.25 μm has been observed. Depth profiles of laser-etched craters indicated a strong dependence on the laser beam profile.