Semiconductor device and method for fabricating the same
A semiconductor device includes a substrate, a gate feature, a gate spacer, and a dielectric layer. The gate feature is above the substrate and includes a gate electrode. The gate spacer is on a sidewall of the gate feature. The dielectric layer is in contact with the gate spacer and has a larger thickness than the gate electrode.
1. A semiconductor device comprising:
a substrate including a bottom portion and a top portion extending from the bottom portion;
an isolation structure surrounding the top portion of the substrate;
a dummy gate feature above the top portion of the substrate and the isolation structure and including a dummy gate electrode;
a first dielectric layer over the dummy gate feature and having a larger thickness than the dummy gate electrode; and
a bit line stack including a first and second bit line conductors, wherein the first dielectric layer has a larger thickness than at least one of the first and the second bit line conductors.
2. The semiconductor device of claim 1 , wherein the dummy gate feature includes a barrier metal and the first dielectric layer has a larger thickness than the barrier metal.
3. The semiconductor device of claim 1 , wherein the dummy gate feature includes a hard mask and the first dielectric layer has a larger thickness than the hard mask.
4. The semiconductor device of claim 1 , further comprising:
a second dielectric layer over the first dielectric layer; and
a third dielectric layer over the second dielectric layer, wherein the third dielectric layer has a smaller thickness than the first dielectric layer.
5. The semiconductor device of claim 1 , wherein the first dielectric layer has a larger thickness than a height of the dummy gate feature.
6. A method for fabricating a semiconductor device, the method comprising:
providing a substrate having a pair of gate features;
forming a spacer layer over the gate features;
removing a portion of the spacer layer to expose top surfaces of the gate features;
forming a first dielectric layer over the spacer layer and the top surface of the gate feature, wherein a first seam is formed in the first dielectric layer between the gate features; and
forming a bit line stack over the substrate, wherein the first dielectric layer has a larger thickness than a bit line conductor of the bit line stack.
7. The method of claim 6 , further comprising forming a second dielectric layer over the first dielectric layer, wherein the first dielectric layer has a larger thickness than the second dielectric layer.
8. The method of claim 6 , further comprising forming a dummy gate feature over the substrate, wherein the first dielectric layer has a larger thickness than a dummy gate electrode of the dummy gate feature.
9. The method of claim 6 , further comprising forming a bit line stack over the substrate, wherein the first dielectric layer has a substantially the same thickness as a bit line dielectric of the bit line stack.
10. The method of claim 6 , further comprising forming a dummy gate feature over the substrate, wherein forming the first dielectric layer is such that a second seam is between the dummy gate feature and the gate features.