Method of producing semiconductor device involving the use of silicon nitride as an oxidation mask

Claim 1

A method of producing a semiconductor device, comprising the sequential steps of: forming desired semiconductor regions in a silicon semiconductor substrate selectively using masking films; removing all of the masking films used in forming the desired semiconductor regions in the semiconductor substrate to expose the entire surface of the semiconductor substrate; forming a first silicon dioxide insulation film on the exposed surface of the substrate; selectively forming a silicon nitride film on the surface of the first insulation film to provide covered and uncovered portions of the first insulation film, said covered portions being over predetermined semiconductor regions; and selectively forming a second silicon dioxide insulation film on the uncovered portions of the first insulation film and into the underlying semiconductor substrate beneath the uncovered portions adjacent the previously-formed predetermined semiconductor regions by using the selectively formed silicon nitride film as an oxidation mask on the covered portions of the first insulation film.

Claim 2

A method of producing a semiconductor device, comprising the sequential steps of: forming desired semiconductor regions in a silicon semiconductor substrate selectively using masking films; removing all of the masking films used in forming the desired semiconductor regions in the semiconductor substrate to expose the entire surface of the semiconductor substrate; forming a first silicon dioxide insulation film on the exposed surface of the substrate; selectively forming a silicon nitride film on the surface of the first insulation film to provide covered and uncovered portions of the first insulation film, said covered portions being over predetermined semiconductor regions; and selectively forming a second silicon dioxide insulation film on the uncovered portions of the first insulation film and into the underlying semiconductor substrate beneath the uncovered portions adjacent the previously-formed predetermined semiconductor regions by using the selectively formed silicon nitride film as an oxidation mask on the covered portions of the first insulation film.

Claim 15

A method of producing a semiconductor device, comprising the steps of: forming desired semiconductor regions in a silicon semiconductor substrate selectively using masking films; removing all of the masking films used in forming the desired semiconductor regions within the silicon semiconductor substrate to expose the entire surface of the substrate; heating the silicon substrate in a mixed gas stream consisting of hydrogen gas, oxygen gas and a gas of a halogen-containing compound to form a first silicon dioxide film on the exposed surface of the silicon substrate; effecting a reaction between monosilane and ammonia to form a silicon nitride film on the surface of the first silicon dioxide film; selectively etching the silicon nitride film to leave predetermined portions of the nitride film thereby to provide covered and uncovered portions of the first silicon dioxide film at predetermined locations; heating the substrate in a mixed gas stream comprising hydrogen gas, oxygen gas and a gas of a halogen-containing compound to form a second silicon dioxide film selectively on the uncovered portions of the first silicon dioxide film and extending into the underlying substrate of the uncovered portions, the remaining predetermined portions of the silicon nitride film acting as an oxidation mask in the selective formation of the second silicon dioxide film; removing the remaining predetermined portions of the silicon nitride film to expose the portions of the first silicon dioxide film beneath said silicon nitride film; forming a third silicon dioxide film covering both the second silicon dioxide film and the exposed portions of the first silicon dioxide film; and forming a silicon dioxide film doped with phosphorus or a mixture of phosphorus and arsenic on the third silicon dioxide film by oxidizing monosilane in the presence of phosphorus or a mixture of phosphorus and arsenic.

Claim 16

A method of producing a semiconductor device, comprising the steps of: forming desired semiconductor regions in a silicon semiconductor substrate selectively using masking films; removing all of the masking films used in forming the desired semiconductor regions within the silicon semiconductor substrate to expose the entire surface of the substrate; heating the silicon substrate in a mixed gas stream consisting of hydrogen gas, oxygen gas and a gas of a halogen-containing compound to form a first silicon dioxide film on the exposed surface of the silicon substrate; effecting a reaction between monosilane and ammonia to form a silicon nitride film on the surface of the first silicon dioxide film; selectively etching the silicon nitride film to leave predetermined portions of the nitride film thereby to provide covered and uncovered portions of the first silicon dioxide film at predetermined locations; heating the substrate in a mixed gas stream comprising hydrogen gas, oxygen gas and a gas of a halogen-containing compound to form a second silicon dioxide film selectively on the uncovered portions of the first silicon dioxide film and extending into the underlying substrate of the uncovered portions, the remaining predetermined portions of the silicon nitride film acting as an oxidation mask in the selective formation of the second silicon dioxide film; removing the remaining predetermined portions of the silicon nitride film to expose the portions of the first silicon dioxide film beneath said silicon nitride film; forming a third silicon dioxide film covering both the second silicon dioxide film and the exposed portions of the first silicon dioxide film; and forming a silicon dioxide film doped with phosphorus or a mixture of phosphorus and arsenic on the third silicon dioxide film by oxidizing monosilane in the presence of phosphorus or a mixture of phosphorus and arsenic.