Method for manufacturing semiconductor device and semiconductor device
According to one embodiment, a method can include dry etching an interlayer insulating layer provided on a foundation layer by using a mask having a plurality of first openings and a plurality of second openings arranged more closely than the first openings to form simultaneously a first hole reaching the foundation layer under each of the first openings and a second hole reaching the foundation layer under the second openings. The first hole reaches the foundation layer without contacting any other first holes. After starting of the dry etching, a plurality of holes are formed under each of the plurality of second openings, and with the progress of the dry etching, the plurality of holes are connected with each other at least at their upper parts including their open ends to form the second hole having an opening area larger than an opening area of the first hole.
1. A semiconductor device, comprising:
a foundation layer including a plurality of semiconductor layers formed in striped patterns;
an interlayer insulating layer provided on the foundation layer;
plural first plugs connected to respective of the semiconductor layers, each of the first plugs provided in a respective first hole which is formed in the interlayer insulating layer and reaches the foundation layer; and
a second plug provided in a second hole which is formed in the interlayer insulating layer and reaches the foundation layer, the second plug connected to the plurality of semiconductor layers,
the second hole including:
an upper part including an opening end having an opening area larger than an opening area of the first hole; and
a lower part including a plurality of holes, each of which is connected in common to the upper part and is diverged from the upper part to reach the foundation layer.
2. The device according to claim 1 , wherein at least one of the holes reaches one of the semiconductor layers.
3. The device according to claim 1 , wherein the plurality of first plugs are arrayed in the direction where the plurality of semiconductor layers are arrayed repeatedly.
4. The device according to claim 1 , wherein the opening end of the upper part of the second hole extends continuously in the direction where the plurality of semiconductor layers are arrayed repeatedly.
5. The device according to claim 1 , wherein the upper part of the second hole extends continuously in the direction where the plurality of semiconductor layers are arrayed repeatedly.
6. The device according to claim 1 , further comprising a plurality of first upper layer wirings respectively extending in the direction to which the semiconductor layers extend, one of the semiconductor layers being connected to one of the first upper layer wirings via one of the first plugs.
7. The device according to claim 1 , further comprising a second upper layer wiring arranged across the plurality of semiconductor layers, the plurality of semiconductor layers being connected via the second plug to the common second upper layer wiring.
8. The device according to claim 1 , further comprising a plurality of floating gates provided alongside in the direction to which the semiconductor layers extend, and covered respectively with an insulator.