Dry etching method

Abstract

A method for dry etching enabling good anisotropic processing even at a wafer cooling temperature closer to room temperature than with conventional low temperature etching. Etching is carried out using an etching gas including a compound containing oxygen (O) as a component element and a compound containing hydrogen (H) as a component element, or using a H.sub.2 O containing gas, while the wafer is cooled to a temperature not higher than 0.degree. C. H.sub.2 O produced or present in an etching system is condensed in a quantity monistically determined by the relation between the amount of the moisture and the dew point and is deposited as ice on a wafer surface. This ice contributes to anisotropic processing by being deposited on a pattern sidewall on which ions are not bombarded in the perpendicular direction. In this manner, etching at a temperature at which ice can be deposited is enabled without regard to the combinations between the layer of a material to be etched and the etching gas. Selectivity may also be improved because the amount of the ion incident energy may be reduced in expectation of the sidewall protection effects of ice. There is no risk of particle contamination because ice may be removed by wafer heating and evacuation to vacuum.