Forming chan-stops by selectively implanting impurity ions through field-oxide layer during later stage of MOS-device fabrication

Claim 1

A method of manufacturing a MOS type semiconductor device comprising the steps of: forming a relatively thick oxide film on a semiconductor substrate; removing a portion of said oxide film to expose a portion of said semiconductor substrate which is used to form an active region; forming a polycrystalline silicon gate electrode on said exposed portion of said semiconductor substrate; forming diffused layers being of a conductivity type opposite to that of said semiconductor substrate in said exposed portion thereof; forming an oxide film on said polycrystalline silicon gate electrode; depositing a polycrystalline silicon film, a silicon nitride film and a resin film on said polycrystalline silicon gate electrode to form a flat surface such that the flat surface of the active region would lie at a level lower than an upper surface of said relatively thick oxide film; etching off said relatively thick oxide film to have a predetermined thickness by utilizing said polycrystalline silicon film, said silicon nitride film, and said resin film as a mask; implanting ions of an impurity into said semiconductor substrate to form channel stop layers; and exposing said polycrystalline silicon film on said diffused layers to form electrodes.

Claim 2

A method of manufacturing a MOS type semiconductor device comprising the steps of: forming a relatively thick oxide film on a semiconductor substrate; removing a portion of said oxide film to expose a portion of said semiconductor substrate which is used to form an active region; forming a polycrystalline silicon gate electrode on said exposed portion of said semiconductor substrate; forming diffused layers being of a conductivity type opposite to that of said semiconductor substrate in said exposed portion thereof; forming an oxide film on said polycrystalline silicon gate electrode; depositing a polycrystalline silicon film, a silicon nitride film and a resin film on said polycrystalline silicon gate electrode to form a flat surface such that the flat surface of the active region would lie at a level lower than an upper surface of said relatively thick oxide film; etching off said relatively thick oxide film to have a predetermined thickness by utilizing said polycrystalline silicon film, said silicon nitride film, and said resin film as a mask; implanting ions of an impurity into said semiconductor substrate to form channel stop layers; and exposing said polycrystalline silicon film on said diffused layers to form electrodes.