Patent ID: 8649226

Claim:
A nonvolatile semiconductor memory device comprising: a substrate; a memory cell transistor located on a first well and comprising a control gate insulation film, a control gate located on the control gate insulation film, a first source and a first drain, the first well being formed in the substrate and being electrically isolated from the substrate; a memory cell comprising the memory cell transistor; a memory cell array comprising a plurality of the memory cells arranged in a matrix; a first bit line electrically connected to a plurality of the first drains located in a first column of the memory cell array; a word line electrically connected to a plurality of the control gate electrodes located in a first row of the memory cell array; a column decoder electrically connected to a second bit line and controlling electric potential of the second bit line; a first transistor located on a second well and comprising a first gate insulation film, a first gate electrode, a second source and a second drain, the second well being electrically isolated from the first well, the first transistor being located between the first bit line and second bit line, the second source being electrically connected to the first bit line, the second drain being electrically connected to the column decoder via the second bit line, the second well being formed in the substrate and being isolated from the substrate; a row decoder electrically connected to the word line and controlling electric potential of the word line, the row decoder comprising a second transistor, the second transistor comprising a second gate insulation film, a second gate electrode, a third source and a third drain, the first gate insulation film being thinner than the second gate insulation film; a first control unit controlling electric potential of the first gate electrode; a first voltage application unit for applying first voltage to the first well; and a second voltage application unit for applying second voltage to the second well.