Method of producing MIS structure

Claim 1

In a method of manufacturing a silicon gate MOS field-effect transistor wherein an oxide film is thermally formed on a silicon substrate, a polycrystalline silicon layer is formed on said oxide film, parts of said oxide film and said polycrystalline silicon layer are etched to form a gate and simultaneously expose parts of said substrate, pent roof portions of the polycrystalline silicon layer extending over said oxide film being formed as a result of the etching of parts of said oxide film and said polycrystalline silicon layer, and impurities are doped into said substrate with said gate used as a mask to thereby form a source and a drain, the improvement comprising the step of: completely removing said pent roof portions of said polycrystalline silicon layer resulting from the etching of said oxide film and said polycrystalline silicon layer by etching a surface of said polycrystalline silicon layer after the formation of said gate or after the doping of said impurities by the use of a liquid etchant whose etching rate is larger for said polycrystalline silicon layer than for said oxide film.

Claim 3

A method of manufacturing a semiconductor device comprising the steps of: a. selectively forming a first layer of insulating material on the surface of a semiconductor substrate on a first conductivity type by forming an initial insulating layer on the surface of said substrate, and removing prescribed portions of said initial layer to expose said substrate therebeneath; b. selectively forming a second layer of material which is at least semiconductive on said initial layer and removing prescribed portions of said second layer over said prescribed portions of said initial layer, while partially overlapping said prescribed portions of said initial layer, so that said second layer does not extend over the side edge of said initial layer; and c. introducing impurities of a second conductivity type, opposite said first conductivity type into the exposed portions of said substrate to form respective semiconductor regions of said second conductivity type therein which extend to the surface of said substrate; and wherein said step (b) further comprises the step of etching both said initial insulating layer and said second layer with a liquid etchant whose etching rate for said second layer is greater than its etching rate for said initial layer, subsequent to step (c) of introducing impurities.

Claim 4

A method of manufacturing a semiconductor device comprising the steps of: a. selectively forming a first layer of insulating material on the surface of a semiconductor substrate on a first conductivity type by forming an initial insulating layer on the surface of said substrate, and removing prescribed portions of said initial layer to expose said substrate therebeneath; b. selectively forming a second layer of material which is at least semiconductive on said initial layer and removing prescribed portions of said second layer over said prescribed portions of said initial layer, while partially overlapping said prescribed portions of said initial layer, so that said second layer does not extend over the side edge of said initial layer; and c. introducing impurities of a second conductivity type, opposite said first conductivity type into the exposed portions of said substrate to form respective semiconductor regions of said second conductivity type therein which extend to the surface of said substrate; and wherein said step (b) further comprises the step of etching both said initial insulating layer and said second layer with a liquid etchant whose etching rate for said second layer is greater than its etching rate for said initial layer, subsequent to step (c) of introducing impurities.

Claim 7

A method of manufacturing a field effect transistor comprising the steps of: a. forming an insulating film on a major surface of a semiconductor body of a first conductivity type; b. selectively forming a conductive film to be used as a gate electrode of said transistor on said insulating layer; c. selectively etching said insulating film to partially expose surface portions of said major surface of said body by using a first etchant whose etching rate for said insulating film is greater than its etching rate for said conductive film, thereby forming pent roof portions of said conductive film which project laterally beyond the underlying insulating film; d. forming a pair of semiconductor regions of a second conductivity type in said semiconductor body by introducing an impurity through said exposed surface portions employing said conductive film and the remaining insulating film as a mask; and e. partially removing prescribed portions of said conductive film by using a second etchant whose etching rate for said conductive film is greater than its etching rate for said insulating film, so that said pent roof portions of said conductive film are completely removed.

Claim 8

A method of manufacturing a field effect transistor comprising the steps of: a. forming an insulating film on a major surface of a semiconductor body of a first conductivity type; b. selectively forming a conductive film to be used as a gate electrode of said transistor on said insulating layer; c. selectively etching said insulating film to partially expose surface portions of said major surface of said body by using a first etchant whose etching rate for said insulating film is greater than its etching rate for said conductive film, thereby forming pent roof portions of said conductive film which project laterally beyond the underlying insulating film; d. forming a pair of semiconductor regions of a second conductivity type in said semiconductor body by introducing an impurity through said exposed surface portions employing said conductive film and the remaining insulating film as a mask; and e. partially removing prescribed portions of said conductive film by using a second etchant whose etching rate for said conductive film is greater than its etching rate for said insulating film, so that said pent roof portions of said conductive film are completely removed.