Semiconductor device and manufacturing method thereof

A method of manufacturing a semiconductor device including a non-volatile memory cell transistor and a plurality of field effect transistors, comprising the steps of:

• simultaneously forming a separation electrode and a floating gate electrode insulated on a semiconductor substrate;
• forming the plurality of field effect transistors on said semiconductor substrate to be electrically separated from each other by said separation electrode;
• and
• forming a non-volatile memory cell transistor by forming a control gate electrode insulated on said floating gate electrode;
• wherein said step of simultaneously forming said separation electrode and said floating gate electrode includes the step of simultaneously forming a first separation electrode for electrically separating said plurality of field effect transistors from each other and a second separation electrode for electrically separating a plurality of said non-volatile memory cell transistors from each other.

A method of manufacturing a semiconductor device including a non-volatile memory cell transistor and a plurality of field effect transistors, comprising the steps of:

• simultaneously forming a separation electrode and a floating gate electrode insulated on a semiconductor substrate;
• forming the plurality of field effect transistors on said semiconductor substrate to be electrically separated from each other by said separation electrode;
• and
• forming a non-volatile memory cell transistor by forming a control gate electrode insulated on said floating gate electrode;
• forming a first impurity region by introducing ions of a first impurity at a portion of said semiconductor substrate which opposes to said gate electrode, forming a second impurity region by implanting ions of a second impurity with a higher dosage than said first impurity ions to a portion of said semiconductor substrate opposing to said floating gate electrode, forming a third impurity region by implanting ions of a third impurity at a dosage not lower than that of said second impurity ions at a portion of said semiconductor substrate opposing to said first separation electrode.