Semiconductor device and method for fabricating the same
A semiconductor device includes a substrate including a trench, a buried gate filling a part of the trench, an inter-layer dielectric layer formed on the buried gate to gap-fill the rest of the trench, and a protection layer covering substantially an entire surface of the substrate including the inter-layer dielectric layer.
1. A semiconductor device, comprising:
a substrate including a trench;
a buried gate filling a part of the trench;
an inter-layer dielectric layer formed on the buried gate to gap-fill the rest of the trench;
a hard mask layer on an active region around the trench; and
a protection layer covering an entire surface of the substrate including the inter-layer dielectric layer and the hard mask layer,
wherein the inter-layer dielectric layer comprises:
a first inter-layer dielectric layer sealing a top surface of the buried gate and an exposed sidewall of the trench; and
a second inter-layer dielectric layer formed on the first inter-layer dielectric layer to gap-fill the rest of the trench,
wherein the first inter-layer dielectric layer comprises a nitride layer and the second inter-layer dielectric layer comprises an oxide layer.
2. The semiconductor device of claim 1 , wherein the protection layer comprises a nitride layer.
3. The semiconductor device of claim 1 , wherein the protection layer comprises a silicon nitride layer formed by a low pressure chemical vapor deposition (LPCVD) process.
4. The semiconductor device of claim 1 , wherein the buried gate comprises one of a titanium nitride (TiN) layer, a tantalum nitride (TaN) layer, a tantalum carbon nitride (TaCN) layer, a tungsten nitride (WN) layer, a tungsten (W) layer and a combination thereof.
5. The semiconductor device of claim 1 , wherein the buried gate comprises a stacked structure of a TiN layer and a W layer.
6. The semiconductor device of claim 1 , wherein the nitride layer comprises a silicon nitride layer formed by an LPCVD process.
7. The semiconductor device of claim 1 , wherein the oxide layer comprises a spin on dielectric layer.
8. A semiconductor device, comprising:
a substrate divided into a peripheral circuit region and a cell region where a trench is formed;
a buried gate filling a part of the trench;
an inter-layer dielectric layer formed on the buried gate to gap-fill the rest of the trench; and
a protection layer covering an entire surface of the substrate corresponding to the cell region without covering the peripheral circuit region,
wherein the inter-layer dielectric layer comprises:
a first inter-layer dielectric layer sealing a top surface of the buried gate and an exposed sidewall of the trench; and
a second inter-layer dielectric layer formed on the first inter-layer dielectric layer to gap-fill the rest of the trench,
wherein the first inter-layer dielectric layer comprises a nitride layer and the second inter-layer dielectric layer comprises an oxide layer.
9. The semiconductor device of claim 8 , further comprising a gate dielectric layer for a transistor formed in the peripheral circuit region over the substrate corresponding to the peripheral region.
10. The semiconductor device of claim 8 , wherein the protection layer comprises a nitride layer.
11. The semiconductor device of claim 8 , wherein the protection layer comprises a silicon nitride layer formed by an LPCVD process.
12. The semiconductor device of claim 8 , wherein the buried gate comprises one of a TiN layer, a TaN layer, a TaCN layer, a WN layer, a W layer and a combination thereof.
13. The semiconductor device of claim 8 , wherein the buried gate comprises a stacked structure of a TiN layer and a W layer.
14. The semiconductor device of claim 8 , wherein the nitride layer comprises a silicon nitride layer formed by an LPCVD process.
15. The semiconductor device of claim 8 , wherein the oxide layer comprises a spin on dielectric layer.
16. The semiconductor device of claim 8 , wherein the inter-layer dielectric layer comprises a nitride layer or an oxide layer.