Patent ID: 8735231

Claim:
A method for manufacturing a semiconductor device comprising the steps of: forming a first insulating layer over a first conductive layer; forming a first semiconductor layer over the first insulating layer; forming a second semiconductor layer over the first semiconductor layer; forming an impurity semiconductor layer over the second semiconductor layer; etching the impurity semiconductor layer, the second semiconductor layer and the first semiconductor layer with a first predetermined mask; forming a second conductive layer over the impurity semiconductor layer; forming a second insulating layer over the second conductive layer; etching the second insulating layer and the second conductive layer with a second predetermined mask to form a pair of second insulating layers and a pair of second conductive layers; etching the impurity semiconductor layer and the second semiconductor layer to form a pair of impurity semiconductor layers and a pair of second semiconductor layers so as to expose the first semiconductor layer between the pair of second semiconductor layers; forming a third insulating layer at least over the pair of second insulating layers, the first semiconductor layer and the first insulating layer; forming a first opening portion in the third insulating layer and the first insulating layer; forming a second opening portion in the third insulating layer and one of the pair of second insulating layers; and forming a third conductive layer over the third insulating layer, wherein a thickness of the first insulating layer is substantially equal to a thickness of the pair of second insulating layers.