Dry etching method

Abstract

Abstract A method for dry etching for forming a contact hole in a silicon oxide interlayer insulating film is proposed, by which high etchrate, high selectivity, low pollution and low damage may be achieved. An etching gas containing cyclic saturated fluorocarbon compounds, such as octafluorocyclobutane (c-C 4 F 8 ), or cyclic unsaturated fluorocarbon compounds, such as hexafluorocyclobutene (c-C 4 F 6 ), is used, and the wafer temperature is controlled to be 50° C. or lower. Both of the compounds are higher fluorocarbon compounds having three or more carbon atoms and yield more CF x + radicals per molecule than does CF 4 or the like compound to enable etching with a high etch rate. Besides, as compared with straight-chain saturated fluorocarbon compounds having the same number of carbon atoms, the above compounds exhibit a higher C/F ratio (the ratio of the number of carbon atoms to that of fluorine atoms per molecule) to permit carbonaceous polymers to be deposited effectively. In this manner, high selectivity and low damage basically may be achieved without using deposition gases simultaneously, with the result that low pollution may also be achieved.

Inventors

• 👤 Toshiharu Yanagida

Bibliographic Details