Non-volatile semiconductor memory device having thin film transistors equipped with floating gates

A non-volatile semiconductor memory device having a plurality of stacked memory transistors, each of the stacked memory transistors comprising:

• a first channel region provided in a surface region of a semiconductor substrate of a first conductivity type;
• first source/drain regions of a second conductivity type provided in the surface region of said semiconductor substrate, said first channel region being provided between said first source/drain regions;
• a first gate insulating film covering said first channel region;
• a first floating gate electrode provided on said first gate insulating film;
• a second gate insulating film covering said first floating gate electrode;
• a control gate electrode provided on said second gate insulating film;
• a third gate insulating film covering said control gate electrode;
• a second floating gate electrode provided on said third gate insulating film;
• a fourth gate insulating film covering said second floating gate electrode;
• a second channel region of the first conductivity type semiconductor thin film provided over said second floating gate electrode with said fourth gate insulating film being interposed therebetween;
• and
• second source/drain regions of the second conductivity type semiconductor thin film formed with said second channel region being interposed therebetween
• said stacked memory transistors being disposed in a matrix form, said first drain and the second drain regions of the stacked memory transistors being connected by bit lines in a column direction and said control gate electrodes of the stacked memory transistors being connected by word lines in a row direction, said first source regions of the stacked memory transistors being commonly connected to form a first source line, said second source regions of the stacked memory transistors being commonly connected to form a second source line, and a particular one of said stacked memory transistors being selected by said word lines, said bit lines and either one of said first and second source lines.