Formation of SiN thin films
Methods of forming silicon nitride thin films on a substrate in a reaction space under high pressure are provided. The methods can include a plurality of plasma enhanced atomic layer deposition (PEALD) cycles, where at least one PEALD deposition cycle comprises contacting the substrate with a nitrogen plasma at a process pressure of 20 Torr to 500 Torr within the reaction space. In some embodiments the silicon precursor is a silyl halide, such as H 2 SiI 2 . In some embodiments the processes allow for the deposition of silicon nitride films having improved properties on three dimensional structures. For example, such silicon nitride films can have a ratio of wet etch rates on the top surfaces to the sidewall of about 1:1 in dilute HF.
1. A method of forming a silicon nitride thin film on a substrate in a reaction space comprising:
a plurality of super-cycles comprising:
a plurality of silicon nitride deposition sub-cycles comprising alternately and sequentially contacting the substrate with a silicon precursor and a nitrogen plasma at a pressure of 5 Torr or less; and
a plurality of high-pressure treatment sub-cycles, wherein at least one of the plurality of high-pressure treatment sub-cycles comprises contacting the substrate with a nitrogen plasma at a pressure of greater than 20 Torr,
wherein the silicon nitride thin film is deposited on a three-dimensional structure on the substrate and a wet etch rate ratio of a wet etch rate of silicon nitride formed on a sidewall surface of the three-dimensional structure to a wet etch rate of the silicon nitride formed on a top surface of the three-dimensional structure is from about 0.8 to about 1.33 in dilute HF.
2. The method of claim 1 , wherein the silicon precursor is H 2 SiI 2 .
3. The method of claim 1 , wherein the nitrogen-containing plasma is generated from a nitrogen precursor selected from the group consisting of NH 3 , N 2 H 4 , an N 2 /H 2 mixture, N 2 , and any mixtures thereof.
4. The method of claim of claim 1 , wherein a wet etch rate ratio of a wet etch rate of silicon nitride formed on a sidewall surface of the three-dimensional structure to a wet etch rate of the silicon nitride formed on a top surface of the three-dimensional structure is 1:1 in dilute HF.
5. The method of claim 1 , wherein the at least one silicon nitride deposition sub-cycle further comprises flowing a carrier gas throughout the at least one silicon nitride deposition sub-cycle.
6. The method of claim 1 , wherein the at least one silicon nitride deposition sub-cycle further comprises flowing a hydrogen-containing gas and a nitrogen-containing gas throughout the at least one silicon nitride deposition sub-cycle.
7. The method of claim 6 , wherein the hydrogen-containing gas and the nitrogen-containing gas are used to form the nitrogen-containing plasma.
8. The method of claim 1 , wherein the at least one high-pressure treatment sub-cycle further comprises flowing a carrier gas throughout the at least one high-pressure treatment sub-cycle.
9. The method of claim 1 , wherein the pressure in the high pressure treatment sub-cycles is 20 Torr to 500 Torr.
10. The method of claim 1 , wherein the pressure in the high pressure treatment sub-cycles is 20 Torr to 30 Torr.