Conformal layers by radical-component CVD
Methods, materials, and systems are described for forming conformal dielectric layers containing silicon and nitrogen (e.g., a silicon-nitrogen-hydrogen (Si—N—H) film) from a carbon-free silicon-and-nitrogen precursor and radical-nitrogen precursor. The carbon-free silicon-and-nitrogen precursor is predominantly excited by contact with the radical-nitrogen precursor. Because the silicon-and-nitrogen film is formed without carbon, the conversion of the film into hardened silicon oxide is done with less pore formation and less volume shrinkage. The deposited silicon-and-nitrogen-containing film may be wholly or partially converted to silicon oxide which allows the optical properties of the conformal dielectric layer to be selectable. The deposition of a thin silicon-and-nitrogen-containing film may be performed at low temperature to form a liner layer in a substrate trench. The low temperature liner layer has been found to improve the wetting properties and allows flowable films to more completely fill the trench.
1. A method of forming a conformal silicon-and-nitrogen-containing layer on a patterned substrate in a substrate processing region in a substrate processing chamber, the method comprising:
mixing a carbon-free silicon-and-nitrogen-containing precursor with a radical-nitrogen precursor, wherein the carbon-free silicon-and-nitrogen-containing precursor is predominantly excited by contact with the radical-nitrogen precursor; and
depositing a conformal silicon-and-nitrogen-containing layer having a conformal layer thickness on the patterned substrate, wherein the patterned substrate comprises a substrate gap.
2. The method of claim 1 wherein a conformal deposition pressure in the substrate processing region during deposition of the conformal silicon-and-nitrogen-containing film is below or about 200 mTorr.
3. The method of claim 1 wherein a conformal deposition temperature of the substrate during deposition of the conformal silicon-and-nitrogen-containing film is below or about 200° C.
4. The method of claim 1 wherein the conformal layer thickness is below or about 20 nm.
5. The method of claim 1 further comprising converting the silicon-and-nitrogen containing layer to a silicon-and-oxygen-containing layer by exposing the silicon-and-nitrogen-containing layer to ozone.
6. The method of claim 1 , wherein the carbon-free silicon-and-nitrogen containing precursor comprises a silyl-amine.
7. The method of claim 6 wherein the silyl-amine comprises N(SiH 3 ) 3 .
8. The method of claim 1 wherein the radical-nitrogen precursor is generated from a nitrogen-and-hydrogen containing gas using a plasma before being mixed with the carbon-free silicon-and-nitrogen containing precursor.
9. The method of claim 8 wherein the nitrogen-and-hydrogen containing gas comprises a gas selected from the group consisting of ammonia, N 2 and H 2 .
10. The method of claim 1 wherein the conformal silicon-and-nitrogen containing layer comprises a carbon-free Si—N—H layer.
11. The method of claim 1 wherein the conformal silicon-and-nitrogen containing layer is converted to a silicon oxide layer by exposing the silicon-and-nitrogen containing layer to an oxygen-containing atmosphere.
12. The method of claim 11 wherein the oxygen-containing atmosphere comprises one or more gases selected from the group consisting of oxygen, ozone, and steam.
13. A method of forming a silicon-containing layer with reduced volume shrinkage, the method comprising:
transferring a substrate containing a gap;
mixing a carbon-free silicon-and-nitrogen-containing precursor with a radical-nitrogen precursor, wherein the carbon-free silicon-and-nitrogen-containing precursor is predominantly excited by contact with the radical-nitrogen precursor;
depositing a conformal silicon-and-nitrogen-containing layer on the substrate, wherein the conformal silicon-and-nitrogen-containing layer has a conformality and is formed from the mixing of the carbon-free silicon-and-nitrogen-containing precursor with the radical-nitrogen precursor; and
depositing a flowable silicon-and-nitrogen-containing layer over the conformal silicon-and-nitrogen-containing layer, wherein the silicon-containing layer comprises both the conformal silicon-and-nitrogen-containing layer and the flowable silicon-and-nitrogen-containing layer.
14. The method of claim 13 further comprising heating the silicon-containing layer in an oxygen-containing atmosphere to increase the oxygen content, wherein the silicon-containing layer retains a volume of about 85% or more of the carbon-free silicon-and-nitrogen containing layer deposited in the gap.
15. The method of claim 13 wherein the conformality of the conformal silicon-and-nitrogen-containing layer is greater than or about 80%.
16. The method of claim 13 wherein the conformal silicon-and-nitrogen containing layer is deposited on the substrate by the reaction of a silicon-and-nitrogen-containing precursor with a radical-nitrogen precursor, wherein the radical-nitrogen precursor provides the dominant excitation to the silicon-and-nitrogen precursor.
17. The method of claim 16 wherein the silicon-and-nitrogen-containing precursor comprises N(SiH 3 ) 3 and the radical-nitrogen precursor is formed from plasma-activated NH 3 .
18. The method of claim 14 wherein the oxygen-containing atmosphere comprises at least one of O 2 , O 3 , or H 2 O.
19. The method of claim 13 wherein the silicon-containing layer in the gap is substantially void-free.
20. The method of claim 16 wherein the silicon-and-nitrogen containing layer comprises a Si—N—H layer.
21. The method of claim 13 wherein the conformal silicon-and-nitrogen-containing layer comprises a Si—N—H layer.
22. The method of claim 13 wherein the substrate gap has a width of about 50 nm or less.