Patent ID: 8114719

Claim:
A write-once memory device comprising: a first memory cell formed over an insulating surface, and comprising a first semiconductor film having at least two first impurity regions and a first region therebetween, a first insulating film over the first semiconductor film, a first gate electrode formed over the first region, and at least two first wirings connected to the respective first impurity regions; and a second memory cell formed over the insulating surface, and comprising a second semiconductor film having at least two second impurity regions and a second region therebetween, a second insulating film over the second semiconductor film, a second gate electrode formed over the second region, and at least two second wirings connected to the respective second impurity regions, wherein the first region is altered to an insulating state and the second region is maintained in an initial state when applying a gate voltage to the first gate electrode and the second gate electrode, a first voltage to at least one of the two first wirings, and a second voltage to at least one of the two second wirings, and wherein the first voltage is lower than the second voltage.