Method of manufacturing non-volatile semiconductor memory device

A method of manufacturing a non-volatile semiconductor memory device having a floating gate for storing data, the method comprising the steps of:

• preparing a semiconductor substrate;
• selectively implanting ions of a fist impurity into said semiconductor substrate to form a channel stop;
• forming a field oxide film on said channel stop to define an element region;
• implanting ions of a second impurity into said semiconductor substrate at said element region to form a first impurity region for receiving a voltage to generate a tunnel current between said first impurity region and said floating gate;
• forming a first insulating film on said element region;
• forming a second insulating film on the resulting structure;
• forming a mask on the second insulating film;
• patterning the mask to form an opening at a tunnel region over said first impurity region and extending at least partially over said field oxide film;
• removing the second insulating film at said tunnel region;
• implanting ions of a third impurity into said semiconductor substrate at said tunnel region using the patterned mask to form a second impurity region;
• removing the mask;
• annealing the resulting structure using said second insulating film as a mask;
• exposing a surface of said semiconductor substrate at said tunnel region by removing the gate insulating film at said tunnel region and the portion of said field oxide film at said tunnel region, wherein said second impurity region prevents said channel stop from being exposed;
• forming a tunnel insulating film through which the tunnel current flows on the exposed surface of said semiconductor substrate;
• and
• forming the floating gate on said first, second, and tunnel insulating films.

A method of manufacturing a non-volatile semiconductor memory device having a floating gate for storing data, the method comprising the steps of:

• forming a field oxide film on a channel stop in a semiconductor substrate of a first conductivity type to define an element region;
• implanting ions of a first impurity of a second conductivity type into the semiconductor substrate in the element region to form a first impurity region for receiving a voltage to generate a tunnel current between said first impurity region and said floating gate;
• forming a gate insulating film on the element region;
• forming a masking material on the resulting structure;
• patterning the masking material to form an opening over the first impurity region and extending at least partially over said field oxide film;
• implanting ions of a second impurity of the second conductivity type into the semiconductor substrate using the patterned masking material as a mask to form a second impurity region;
• exposing a surface of said semiconductor substrate at said tunnel region by removing the gate insulating film at said tunnel region and the portion of said field oxide film at said tunnel region, wherein said second impurity region prevents said channel stop from being exposed;
• removing the masking material;
• forming a tunnel insulating film through which the tunnel current flows on the surface of that portion of the semiconductor substrate from which the gate insulating film and the field oxide film have been removed;
• and
• forming the floating gate on the gate and tunnel insulating films.