Patent ID: 8400817

Claim:
A semiconductor device comprising: a source line; a bit line; a first signal line; a second signal line; a word line; a memory cell array comprising a plurality of memory cells; a first driver circuit electrically connected to the source line and the bit line; a second driver circuit electrically connected to the first signal line; a third driver circuit electrically connected to the second signal line; and a fourth driver circuit electrically connected to the word line, wherein one of the plurality of memory cells comprises: a first transistor comprising a first gate electrode, a first source electrode, and a first drain electrode; a second transistor comprising a second gate electrode, a second source electrode, and a second drain electrode; and a capacitor comprising a first terminal and a second terminal, wherein the second transistor comprises an oxide semiconductor material, wherein the first gate electrode, one of the second source electrode and the second drain electrode, and the first terminal of the capacitor are electrically connected to one another, wherein the source line and the first source electrode are electrically connected to each other, wherein the bit line and the first drain electrode are electrically connected to each other, wherein the first signal line and the other of the second source electrode and the second drain electrode are electrically connected to each other, wherein the second signal line and the second gate electrode are electrically connected to each other, wherein the word line and the second terminal of the capacitor are electrically connected to each other, and wherein the first transistor comprises: a channel formation region comprising a semiconductor material other than an oxide semiconductor; impurity regions provided with the channel formation region sandwiched therebetween; a gate insulating layer over the channel formation region; the first gate electrode over the gate insulating layer; and the first source electrode and the first drain electrode electrically connected to the impurity regions.