Method of forming pre-metal dielectric layer
View Patent ↗A method of forming a pre-metal dielectric (PMD) layer is disclosed. In the method, after a nitride liner layer is formed on a substrate having a transistor, a USG layer is deposited thereon and then planarized. Next, ion implantation and annealing are performed for gettering, first in a gate region and then in a non-gate region of the USG layer. The USG layer is generally free from plasma damage and has a good gap-fill capability. Further, ion implantation and annealing after deposition of the USG layer may enhance a gap-fill capability, a gettering capability, and electrical properties of a transistor.
1. A method of forming a pre-metal dielectric (PMD) layer, the method comprising:
forming a nitride liner layer on a substrate containing a transistor;
depositing an undoped silica glass (USG) layer on the nitride liner layer and then planarizing the USG layer;
performing a first ion implantation and a first annealing in a first selected region of the USG layer; and
performing a second ion implantation and a second annealing in a second selected region of the USG layer,
wherein one of the first and second regions corresponds to a transistor gate region.
2. The method of claim 1 , wherein the USG layer comprises O 3 tetraethyl orthosilicate (TEOS) or atomic layer deposition (ALD) TEOS.
3. The method of claim 1 , further comprising:
before depositing the USG layer, implanting fluorine ions into the nitride liner layer and heating.
4. The method of claim 1 , wherein the first and second ion implantations for gettering use nitrogen ions, phosphorus ions, or arsenic ions.
5. The method of claim 1 , wherein the first and second annealing comprises heating in a furnace for 10 minutes to 80 minutes at a temperature of 600° C. to 1200° C.
6. The method of claim 1 , wherein the first and second annealing comprises rapid thermal annealing for 10 seconds to 80 seconds at a temperature of 600° C. to 1200° C.
7. The method of claim 1 , wherein the USG layer comprises TEOS.
8. The method of claim 1 , wherein one of the first and second regions consists essentially of a transistor gate region.
9. The method of claim 8 , wherein the other of the first and second regions consists essentially of a non-gate region.
10. The method of claim 1 , further comprising forming a mask substantially covering regions other than the transistor gate region.
11. The method of claim 1 , further comprising forming a first mask substantially covering regions other than the transistor gate region before performing the ion implantation and annealing in the transistor gate region.
12. The method of claim 11 , further comprising forming a second mask substantially covering the transistor gate region before performing the other ion implantation and annealing.
13. The method of claim 1 , wherein the first and second ion implantations improves the gettering capability of the PMD layer.
14. The method of claim 13 , wherein at least one of the first and second ion implantations further improves the reflow capability of the PMD layer.
15. The method of claim 1 , wherein the ion implantation in the transistor gate region comprises implanting at least one first ion selected from the group consisting of nitrogen, phosphorous and arsenic.
16. The method of claim 13 , wherein the other ion implantation comprises implanting at least one second ion selected from the group consisting of nitrogen, phosphorous and arsenic.
17. The method of claim 14 , wherein at least one of the first and second ions further comprises boron.
18. The method of claim 14 , wherein each of the first and second ions consist essentially of phosphorous.