| abstract |
SUMMARY OF THE INVENTION The present invention provides a semiconductor device occupying a small area and having a high degree of integration. The semiconductor device includes a first insulating layer, a conductive layer, and a second insulating layer. The conductive layer is between the first insulating layer and the second insulating layer. The first insulating layer, the conductive layer, and the second insulating layer overlap each other in the region. The contact plug passes through the first insulating layer, the conductive layer, and the second insulating layer. In the depth direction from the second insulating layer to the first insulating layer, the diameter of the contact plug changes to a smaller value at the interface between the second insulating layer and the conductive layer. |