Semiconductor device having buried word line and method of manufacturing the same
The present disclosure provides a semiconductor device. The semiconductor device can be a recessed access device (RAD) transistor, which includes a substrate, a word line disposed in the substrate and surrounded by a dielectric liner, an isolation layer disposed in the substrate to cap the word line, and an insulative plug penetrating through the isolation layer and extending into the word line.
1. A semiconductor device, comprising:
a substrate;
a word line disposed in the substrate;
a dielectric liner disposed between the substrate and the word line;
an isolation layer disposed in the substrate to cap the word line; and
an insulative plug penetrating through the isolation layer and extending into the word line.
2. The semiconductor device of claim 1 , wherein the insulative plug and the word line are concentric.
3. The semiconductor device of claim 1 , wherein the word line has a first width, and the insulative plug has a second width less than the first width.
4. The semiconductor device of claim 3 , wherein the second width gradually decreases at positions of increasing distance from an upper surface of the substrate.
5. The semiconductor device of claim 1 , wherein the insulative plug is entirely surrounded by the isolation layer.
6. The semiconductor device of claim 1 , wherein the insulative plug has a first dielectric constant, and the isolation layer has a second dielectric constant greater than the first dielectric constant.
7. The semiconductor device of claim 1 , further comprising a void introduced in the isolation layer.
8. The semiconductor device of claim 7 , wherein the void extends around a perimeter of the insulative plug.
9. The semiconductor device of claim 1 , further comprising a plurality of impurity regions in the substrate and disposed on either side of the word line.