Surface preparation prior to deposition
View Patent ↗Methods are provided herein for treating substrate surfaces in preparation for subsequent nucleation-sensitive depositions (e.g., polysilicon or poly-SiGe) and adsorption-driven deposition (e.g. atomic layer deposition or ALD). Prior to depositing, the surface is treated with non-depositing plasma products. The treated surface more readily nucleates polysilicon and poly-SiGe (such as for a gate electrode), or more readily adsorbs ALD reactants (such as for a gate dielectric). The surface treatment provides surface moieties more readily susceptible to a subsequent deposition reaction, or more readily susceptible to further surface treatment prior to deposition. By changing the surface termination of the substrate with a low temperature radical treatment, subsequent deposition is advantageously facilitated without depositing a layer of any appreciable thickness and without significantly affecting the bulk properties of the underlying material. Preferably less than 10 Å of the bulk material incorporates the excited species, which can include fluorine, chlorine and particularly nitrogen excited species.
1. A method comprising:
forming a layer of dielectric material over a substrate;
exposing the layer of dielectric material to a source of nitrogen excited species, wherein exposing incorporates less than about 10 atomic percent nitrogen at a depth of greater than about 10 Å from an upper surface of the layer of dielectric material; and
depositing a conductor over the layer of dielectric material after exposing the layer of dielectric material to the source of nitrogen excited species, wherein the conductor contacts a portion of the layer of dielectric material exposed to the source of nitrogen excited species.
2. The method of claim 1 , wherein the substrate is electrically conductive.
3. The method of claim 1 , wherein the layer of dielectric material is a transistor gate dielectric layer.
4. The method of claim 1 , wherein the layer of dielectric material has a dielectric constant of greater than about 4.
5. The method of claim 1 , wherein exposing incorporates less than about 1 atomic percent nitrogen at a depth of greater than about 10 Å from the surface.
6. The method of claim 1 , wherein the layer of dielectric material comprises a material selected from the group consisting of aluminum oxide, zirconium oxide, hafnium oxide, tantalum oxide, barium strontium titanate and strontium bismuth tantalate.
7. The method of claim 6 , wherein the layer of dielectric material comprises zirconium oxide.
8. The method of claim 1 , wherein forming the layer of dielectric material comprises an atomic layer deposition.
9. The method of claim 1 , wherein depositing the conductor comprises a chemical vapor deposition.