High density N-channel silicon gate read only memory

A method of making a semiconductor device comprising the steps of:

• masking a plurality of elongated parallel areas on a face of a semiconductor wafer with a material which inhibits oxidation;
• growing a thick field oxide on said face while leaving unoxidized a plurality of elongted parallel regions;
• removing the masking material;
• introducing a conductivity type determining impurity into said face of said semiconductor wafer to heavily-dope the plurality of elongated regions;
• selectively removing the thick field oxide in areas between a plurality of the elongated regions;
• growing thin gate oxide in such areas;
• and providing a plurality of strips of conductive material over the field oxide generally perpendicular to the elongated regions extending across the plurality of areas.

A method of making an N-channel read only memory comprising the steps of:

• masking a plurality of elongated parallel areas on a face of a semiconductor body with a material which inhibits oxidationl;
• growing a thick field oxide on said face while leaving unoxidized a plurality of elongated parallel regions at said parallel areas;
• removing the masking material;
• introducing a conductivity type determining impurity into said face of the semiconductor body to heavily dope the plurality of elongated regions;
• selectively removing the thick field oxide in selected areas between a plurality of the elongated regions while leaving other such areas of field oxide intact to program the memory in a pattern of logic ones and zeros;
• forming thin gate dielectric in the selected areas;
• and providing a plurality of strips of conductive material over the field oxide generally perpendicular to the elongated regions extending across the selected areas.