Light-induced dry etching of semiconductors in the vacuum ultraviolet

The dry etching of Si with XeF₂ and of GaAs with Cl₂ in a wavelength range around 120 nm combines very high efficiency with excellent selectivity and provides a perspective to reach lateral resolutions required in about 10 years. Projection optics based on conventional optical materials and light sources seem to be feasible. The high quantum efficiencies between 10 and 100 removed atoms per photon originate from chain reactions. The relevant reactions are initiated by excitation of surface layers which provides the high selectivity. Optimal etching conditions concerning dark reaction and nonselective reactions are specified. The influence of the chain reactions on the topography is investigated.