Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
262 words
A method of manufacturing a vertical double diffusion MOS transistor, comprising the steps of: contacting first and second insulating layers formed on the opposing surface of first and second semiconductor substrates and having first and second conductivity types; converting said first and second insulating layers to a third insulating layer by thermal treatment, said third insulating layer being a unitary body of said first and second insulating layers; forming a groove in said first semiconductor substrate, said groove reaching to said third insulating layer; forming a fourth insulating layer covering the entire surface of said first semiconductor substrate and filling said groove; forming first and second insulating films by selectively removing said forth insulating layer, said first and second insulating films serving as a gate insulating film of the MOS transistor; forming a conductive layer of the second conductivity type on a portion of said first insulating film and on a portion of said fourth insulating layer, said conductive layer serving as a gate electrode of the MOS transistor; forming a first conductive region of the second conductivity type by means of ion implantation and thermal diffusion, said first conductive region serving as a channel region of the MOS transistor, located underneath said first insulating film, and extending from the surface of said first semiconductor substrate to said third insulating layer and said groove; and forming first and second high impurity regions of the first conductivity type underneath said first and second insulating films, said first and second high impurity regions serving as a source and a drain of the MOS transistor.
Claim 2
Independent Claim
262 words
A method of manufacturing a vertical double diffusion MOS transistor, comprising the steps of: contacting first and second insulating layers formed on the opposing surface of first and second semiconductor substrates and having first and second conductivity types; converting said first and second insulating layers to a third insulating layer by thermal treatment, said third insulating layer being a unitary body of said first and second insulating layers; forming a groove in said first semiconductor substrate, said groove reaching to said third insulating layer; forming a fourth insulating layer covering the entire surface of said first semiconductor substrate and filling said groove; forming first and second insulating films by selectively removing said forth insulating layer, said first and second insulating films serving as a gate insulating film of the MOS transistor; forming a conductive layer of the second conductivity type on a portion of said first insulating film and on a portion of said fourth insulating layer, said conductive layer serving as a gate electrode of the MOS transistor; forming a first conductive region of the second conductivity type by means of ion implantation and thermal diffusion, said first conductive region serving as a channel region of the MOS transistor, located underneath said first insulating film, and extending from the surface of said first semiconductor substrate to said third insulating layer and said groove; and forming first and second high impurity regions of the first conductivity type underneath said first and second insulating films, said first and second high impurity regions serving as a source and a drain of the MOS transistor.
Claim 3
Dependent Claim
36 words
A method according to claim 1, wherein the step of converting said first and second insulating layers to said third insulating layer is a step of performing a thermal treatment at 1,000° C. for 30 minutes.
Claim 4
Dependent Claim
53 words
A method according to claim 1, wherein the step of forming said fourth insulating layer is a step of forming a silicon oxide film by oxidizing the surface of said first semiconductor substrate by means of a thermal oxidation process and forming an additional silicon oxide film by means of a CVD process.