Patent ID: 8450145

Claim:
A method for producing a nonvolatile semiconductor memory device comprising: forming a first metal wiring and a second metal wiring on a substrate; forming an interlayer insulation film on a whole surface to cover the first metal wiring and the second metal wiring; forming a first opening having a depth to reach the first metal wiring, in the interlayer insulation film on the first metal wiring, and forming a second opening having a depth to reach the second metal wiring, in the interlayer insulation film on the second metal wiring; depositing a variable resistor on a whole surface so as not to completely fill the first opening and the second opening, and so as not to cover in the first opening and the second opening, depositing a first electrode on a whole surface so as to completely fill the first opening but not to completely fill and not to cover in the second opening; back-etching the first electrode both in the first opening and in the second opening simultaneously, until a surface of the variable resistor is exposed in the second opening, with the first opening filled with the first electrode; back-etching the variable resistor both in the first opening and in the second opening simultaneously, until a surface of the second metal wiring is exposed in the second opening, with the first opening filled with the first electrode; forming a third metal wiring on the second metal wiring exposed in the second opening, and on the first electrode formed in the first opening; and wherein at least one of a shape or a size of the first opening is different from that of the second opening.