Dry etching method

Abstract

A dry etching method enabling etching of a layer of a copper (Cu) based material at a wafer heating temperature lower than heretofore, and a practically useful method for detecting the end point of etching. If the Cu layer is etched using an etching gas including a compound containing chlorine (Cl) and oxygen (O) as component elements or an etching gas including a compound containing Cl and a compound containing O as component elements, respectively, the Cu layer is removed not only in the form of copper chloride CuCl.sub.x but in the form of copper oxychloride CuCl.sub.x O.sub.y, where x is 1 to 2 and y is 1 to 8. Since CuCl.sub.x O.sub.y has a vapor pressure lower than that of CuCl.sub.x, a conventional etching reaction product, it is unnecessary to heat the wafer to higher temperatures as in the conventional practice, while there is no risk of a copper oxide film being formed on the surface of the Cu layer. The end point of etching may be detected by detecting a decrease in emission peak intensities in the molecular spectrum of CuCl appearing the specific wavelengths, such as 402 nm or 433 nm.