Depositing tungsten into high aspect ratio features
Methods and apparatuses for filling high aspect ratio features with tungsten-containing materials in a substantially void-free manner are provided. In certain embodiments, the method involves depositing an initial layer of a tungsten-containing material followed by selectively removing a portion of the initial layer to form a remaining layer, which is differentially passivated along the depth of the high-aspect ration feature. In certain embodiments, the remaining layer is more passivated near the feature opening than inside the feature. The method may proceed with depositing an additional layer of the same or other material over the remaining layer. The deposition rate during this later deposition operation is slower near the feature opening than inside the features due to the differential passivation of the remaining layer. This deposition variation, in turn, may aid in preventing premature closing of the feature and facilitate filling of the feature in a substantially void free manner.
1. A method of filling a high aspect ratio feature provided on a substrate, the method comprising:
introducing a tungsten-containing precursor and a reducing agent into a processing chamber;
depositing a layer of a tungsten-containing material on the substrate via a chemical vapor deposition reaction between the tungsten-containing precursor and the reducing agent, such that the layer partially fills the high aspect ratio feature; and
selectively removing a portion of the layer using an etching material to form a remaining layer,
wherein the selective removal is performed without using an in-situ plasma and further wherein the selective removal is performed in a mass transport regime corresponding to a lower concentration of the etching material inside the high aspect ratio feature than near the opening of the high aspect ratio feature, wherein the etching material comprises multiple components, the multiple components having different relative concentrations throughout the depth of the high aspect ratio feature during the selective removal.
2. The method of claim 1 , wherein a temperature of the substrate during selective removal is at least about 300 degrees Centigrade.
3. The method of claim 1 , wherein the etching material comprises one or more of molecular fluorine and atomic fluorine.
4. The method of claim 1 , wherein the etching material is introduced into the processing chamber at a flow rate of less than about 2,000 sccm to achieve the mass transport regime.
5. The method of claim 1 , wherein the etching material is introduced into the processing chamber at a flow rate of less than about 1,000 sccm to achieve the mass transport regime.
6. The method of claim 1 , wherein the etching material is introduced into the processing chamber at a flow rate of less than about 500 sccm to achieve the mass transport regime.
7. The method of claim 1 further comprising repeating the deposition operation and the selective removal operation.
8. The method of claim 7 , wherein the selective removal operation is repeated using different process conditions than the prior selective removal operation.
9. The method of claim 1 , wherein depositing the layer of a tungsten-containing material and selectively removing the portion of the layer is performed in the same processing chamber.
10. The method of claim 9 , wherein depositing the layer of a tungsten-containing material and selectively removing the portion of the layer is performed on different stations.
11. The method of claim 9 , wherein depositing the layer of a tungsten-containing material and selectively removing the portion of the layer is performed on a same station.
12. The method of claim 1 , wherein depositing the layer of a tungsten-containing material and selectively removing the portion of the layer is performed in different processing chambers.
13. The method of claim 1 , wherein the etching material is introduced into the processing chamber from a remote plasma generator.