Oxide-rich liner layer for flowable CVD gapfill
The formation of a gap-filling silicon oxide layer with reduced volume fraction of voids is described. The deposition involves the formation of an oxygen-rich less-flowable liner layer before an oxygen-poor more-flowable gapfill layer. However, the liner layer is deposited within the same chamber as the gapfill layer. The liner layer and the gapfill layer may both be formed by combining a radical component with an unexcited silicon-containing precursor (i.e. not directly excited by application of plasma power). The liner layer has more oxygen content than the gapfill layer and deposits more conformally. The deposition rate of the gapfill layer may be increased by the presence of the liner layer. The gapfill layer may contain silicon, oxygen and nitrogen and be converted at elevated temperature to contain more oxygen and less nitrogen. The presence of the gapfill liner provides a source of oxygen underneath the gapfill layer to augment the gas phase oxygen introduced during the conversion.
1. A method of forming a silicon oxide layer on a patterned substrate containing a trench, the method comprising:
transferring the substrate into a substrate processing chamber;
forming an oxygen-rich liner layer on the substrate including in the trench;
forming a gapfill dielectric layer on the substrate and in the trench, wherein the gapfill dielectric layer has a lower oxygen content than the oxygen-rich liner layer and the gapfill dielectric layer is flowable during formation; and
curing the gapfill dielectric layer at an elevated temperature to transfer some of the oxygen from the oxygen-rich liner layer into the gapfill dielectric layer.
2. The method of claim 1 , wherein the oxygen-rich liner layer is more conformal than the gapfill dielectric layer.
3. The method of claim 1 , wherein the gapfill dielectric layer substantially tills the trench.
4. The method of claim 1 , wherein forming the gapfill dielectric layer comprises:
flowing a gapfill plasma precursor into a remote plasma region to form plasma effluents; and
combining the plasma effluents with a flow of a silicon-containing precursor in the substrate processing region to form the gapfill dielectric layer, wherein the silicon-containing precursor is not directly excited by an application of plasma power and the gapfill dielectric layer is a silicon-and-oxygen-containing layer.
5. The method of claim 1 , wherein forming the oxygen-rich liner layer comprises:
flowing a liner plasma precursor into a remote plasma region to form plasma effluents; and
combining the plasma effluents with a flow of a silicon-containing precursor in the substrate processing region to form the oxygen-rich liner layer, wherein the silicon-containing precursor is not directly excited by an application of plasma power and the gapfill dielectric layer is a silicon-and-oxygen-containing layer.
6. The method of claim 4 , wherein the operation of flowing the gapfill plasma precursor comprises flowing oxygen and nitrogen into the remote plasma region with a gapfill atomic oxygen-to-nitrogen flow rate ratio.
7. The method of claim 5 , wherein the operation of flowing the liner plasma precursor comprises flowing oxygen and nitrogen into the remote plasma, region with a liner atomic-oxygen-to-nitrogen flow rate ratio.
8. The method of claim 7 , wherein the liner atomic-oxygen-to-nitrogen flow rate ratio exceeds the gapfill atomic-oxygen-to-nitrogen flow rate ratio such that the oxygen content of the oxide-rich liner exceeds that of the gapfill dielectric layer.
9. The method of claim 8 , wherein the liner atomic-oxygen-to-nitrogen flow rate ratio exceeds the gapfill atomic-oxygen-to-nitrogen flow rate ratio by a multiplicative factor greater than 5.
10. The method of claim 4 , wherein the silicon-containing precursor comprises a silicon-and-nitrogen-containing precursor and the plasma effluents comprise a radical-nitrogen precursor.
11. The method of claim 10 , wherein the silicon-and-nitrogen-containing precursor comprises at least one of H 2 N(SiH 3 ), HN(SiH 3 ) 2 , and N(SiH 3 ) 3 and the plasma precursor comprises at least one of NH 3 , NH 4 OH, N 2 O, NO, NO 2 , N 2 and H 2 .
12. The method of claim 4 , wherein the remote plasma region is within the substrate processing chamber and separated from the substrate processing chamber by a showerhead.
13. The method of claim 1 , wherein the operation of curing the gapfill dielectric layer comprises exposing the gapfill dielectric layer to an ozone-containing atmosphere at the elevated temperature.
14. The method of claim 13 , wherein the operation of curing the gapfill dielectric layer further comprises subsequently exposing the gapfill dielectric layer to an oxygen-containing atmosphere comprising at least one of O 2 , O 3 and H 2 O, at an annealing temperature greater than the elevated temperature.
15. The method of claim 1 , wherein the trench has a width of about 50 nm or less.