Dry etching method

U.S. Patent Number: 5391244

Abstract: A dry etching method for performing one-stage anisotropic etching of a W-polycide film without using a CFC (chlorofluorocarbon) gas is disclosed. The W-polycide film on a substrate is etched by using sulfur halide such as S.sub.2 Cl.sub.2 and S.sub.2 Br.sub.2 for an etching gas while heating the substrate within a temperature range of up to 90.degree. C. Free S released from the sulfur halide is deposited on the substrate within the temperature range, thereby contributing to improvement of selectivity and anisotropy, and Cl.sup.* and Br.sup.* become etchants. Although WCl.sub.x and WBr.sub.x, which are etching reaction products, have low vapor pressure at a normal temperature and under normal pressure, WCl.sub.x and WBr.sub.x may be eliminated sufficiently under reduced pressure and heated conditions. Since F.sup.* is not formed in a plasma, no undercut is generated on an underlying polysilicon layer. Also, since C does not exist, particle pollution can be prevented and selectivity for a gate oxide film can be improved. If a nitrogen based compound, such as N.sub.2, is added to the sulfur halide, deposition of sulfur nitride based compounds can be expected, and the wafer heating temperature can be raised up to 130.degree. C.

Inventors: Kadomura; Shingo (Kanagawa, JP)

Assignee: Sony Corporation (Tokyo, JP)

Application Number: 08/013,325

Issued: 1995-02-21

Expired: 2007-02-21

Classes: 438/695 ; 257/E21.312; 257/E21.314; 430/323; 438/696; 438/715; 438/721

Field of search: 156/643,646,662,656,657,655,659.1,661.1,651,653

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