Method of producing semiconductor memory

A method of producing a semiconductor memory including a plurality of memory cell transistors formed on a semiconductor substrate, each of said memory cell transistors including a laminated gate formed of a floating gate and a control gate, comprising the steps of:

• forming a plurality of element separation regions in the semiconductor substrate in a row direction and a column direction for separating the memory cell transistors;
• forming a gate oxide film on the semiconductor substrate;
• forming a first conductive layer on the gate oxide film;
• etching the first conductive layer to form a plurality of slits;
• forming spacers on sidewall portions of each of the slits;
• forming a first insulating film on the first conductive layer, the spacers, and the semiconductor substrate;
• forming a second conductive layer on the first insulating film;
• etching the first conductive layer, the second conductive layer, and the first insulating film using one single mask to form the laminated gate;
• implanting a conductive impurity into the semiconductor substrate exposed on both sides of the laminated gate to form a drain/source region;
• forming an interlayer insulating film;
• and
• forming a contact hole penetrating the interlayer insulating film to reach the semiconductor substrate.