Selective etching method for III-V group semiconductor material using a mixed etching gas and a stop-etching gas

Claim 1

A selective etching method comprising etching a III-V group compound semiconductor free from Al, said III-V group compound semiconductor free from Al being adjacent to a III-V group compound semiconductor containing Al, using a mixed gas containing a fluoride stop-etching gas containing C and F as constituent elements and a chloride etching gas consisting of Si and Cl as constituent elements, wherein the III-V group compound semiconductor containing Al is a compound semiconductor composed at least of Al, Ga and As and wherein said III-V group compound semiconductor which are free from Al are compound semiconductors at least composed of Ga and As and are free from Al, wherein the stop-etching gas consisting of C and F as constituent elements is at least one fluorocarbon based gas selected from the group consisting of CF 4 , C 2 F 6 , C 3 F 8 , CHF 3 , CH 2 F 2 and CBrF 3 and wherein the etching gas consisting of Si and Cl as constituent gases is at least one silane-based gas selected from the group consisting of SiCl 4 , SiH 2 Cl 2 and SiHCl 3 , and wherein a rare gas is additionally contained in the mixed gas and is one or more gases selected from the group consisting of He, Ne, Ar, Kr, Xe and Rn.

Claim 3

A method for producing a field effect transistor comprising a step of forming a channel region on a substrate, a step of forming a layer of a first compound semiconductor comprising at least Al, Ga and As, a step of forming a layer of a second compound semiconductor comprising at least Ga and As and free from Al, and a step of selectively etching the layer of the second compound semiconductor on other layer of the first compound semiconductor using a mixed gas consisting of a stop-etching fluorocarbon based gas and an etching silane based gas, characterized by further comprising a step of forming a gate electrode on a region on the substrate from which the layer of the second compound semiconductor has been selectively etched to expose the layer of the first compound semiconductor, in which said stop-etching fluorocarbon gas and said etching silane based gas of the mixed gas employed in the selective etching are at least one selected from the group consisting of CE 4 , C 2 F 6 , C 3 F 8 , CHF 3 , CH 2 F 2 and CbrF 3 and at least one selected from the group consisting of SiCl 4 , SiH 2 Cl 2 and SiHCl 3 , and wherein a rare gas is additionally contained in the mixed gas employed in the step of selective etching and is one or more gases selected from the group consisting of He, Ne, Ar, Kr, Xe and Rn.

Claim 4

A method for producing a field effect transistor comprising a step of forming a channel region on a substrate, a step of forming a layer of a first compound semiconductor comprising at least Al, Ga and As, a step of forming a layer of a second compound semiconductor comprising at least Ga and As and free from Al, and a step of selectively etching the layer of the second compound semiconductor on other layer of the first compound semiconductor using a mixed gas consisting of a stop-etching fluorocarbon based gas and an etching silane based gas, characterized by further comprising a step of forming a gate electrode on a region on the substrate from which the layer of the second compound semiconductor has been selectively etched to expose the layer of the first compound semiconductor, in which said stop-etching fluorocarbon gas and said etching silane based gas of the mixed gas employed in the selective etching are at least one selected from the group consisting of CE 4 , C 2 F 6 , C 3 F 8 , CHF 3 , CH 2 F 2 and CbrF 3 and at least one selected from the group consisting of SiCl 4 , SiH 2 Cl 2 and SiHCl 3 , and wherein a rare gas is additionally contained in the mixed gas employed in the step of selective etching and is one or more gases selected from the group consisting of He, Ne, Ar, Kr, Xe and Rn.