Atomic layer deposition of indium gallium zinc oxide
Methods of forming indium gallium zinc oxide (IGZO) films by vapor deposition are provided. The IGZO films may, for example, serve as a channel layer in a transistor device. In some embodiments atomic layer deposition processes for depositing IGZO films comprise an IGZO deposition cycle comprising alternately and sequentially contacting a substrate in a reaction space with a vapor phase indium precursor, a vapor phase gallium precursor, a vapor phase zinc precursor and an oxygen reactant. In some embodiments the ALD deposition cycle additionally comprises contacting the substrate with an additional reactant comprising one or more of NH 3 , N 2 O, NO 2 and H 2 O 2 .
1. An atomic layer deposition (ALD) process for forming an indium gallium zinc oxide (IGZO) channel layer in a transistor device, the ALD process comprising a deposition cycle comprising alternately and sequentially contacting a substrate in a reaction space with a vapor phase indium precursor, a vapor phase gallium precursor, a vapor phase zinc precursor and an oxygen reactant, and repeating the deposition cycle until a IGZO thin film of a desired thickness has been formed, wherein the deposition cycle comprises a zinc indium oxide sub-cycle that is repeated N1 times and comprises alternately and sequentially contacting the substrate with the zinc precursor, the indium precursor and the oxygen reactant and a gallium oxide sub-cycle that is repeated N2 times and comprises alternately and sequentially contacting the substrate with the gallium precursor and the oxygen reactant, where N is an integer.
2. The process of claim 1 , wherein the gallium precursor comprises at least one amine or alkylamine ligand.
3. The process of claim 1 , wherein the zinc precursor comprises one or more of elemental zinc, a zinc halide, and an alkyl zinc compound.
4. The process of claim 1 , wherein the indium precursor comprises one or more of an indium alkyl, an indium beta diketonate, an indium cyclopentadienyl, and an indium halide.
5. The process of claim 1 , wherein the indium precursor is trimethyl indium, the zinc precursor is diethyl zinc and the gallium precursor is Ga(NMe 2 ) 3 ).
6. The process of claim 1 , wherein the substrate is contacted with a surface modification agent before the substrate is contacted with the vapor phase indium precursor, before the substrate is contacted with the vapor phase gallium precursor, and/or before the substrate is contacted with the vapor phase zinc precursor.
7. The process of claim 6 , wherein the surface modification agent reacts with OH groups on the substrate surface and wherein the surface modification agent comprises an alcohol or acid anhydride.
8. The process of claim 1 , wherein the substrate is contacted with a dopant precursor comprising a cerium precursor, a tantalum precursor, a silicon precursor, and/or a germanium precursor.
9. An atomic layer deposition (ALD) process for forming an indium gallium zinc oxide (IGZO) channel layer in a transistor device, the ALD process comprising a deposition cycle comprising alternately and sequentially contacting a substrate in a reaction space with a vapor phase indium precursor, a vapor phase gallium precursor, a vapor phase zinc precursor and an oxygen reactant, and repeating the deposition cycle until a IGZO thin film of a desired thickness has been formed, wherein the deposition cycle comprises a zinc gallium oxide sub-cycle that is repeated N1 times and comprises alternately and sequentially contacting the substrate with the zinc precursor, the gallium precursor and the oxygen reactant; and an indium oxide sub-cycle that is repeated N2 times and comprises alternately and sequentially contacting the substrate with the indium precursor and the oxygen reactant, where N is an integer.
10. The process of claim 9 , wherein the gallium precursor comprises at least one amine or alkylamine ligand.
11. The process of claim 9 , wherein the zinc precursor comprises one or more of elemental zinc, a zinc halide, and an alkyl zinc compound.
12. The process of claim 9 , wherein the indium precursor comprises one or more of an indium alkyl, an indium beta diketonate, an indium cyclopentadienyl, and an indium halide.
13. The process of claim 9 , wherein the indium precursor is trimethyl indium, the zinc precursor is diethyl zinc and the gallium precursor is Ga(NMe 2 ) 3 ).
14. The process of claim 9 , wherein the substrate is contacted with a surface modification agent before the substrate is contacted with the vapor phase indium precursor, before the substrate is contacted with the vapor phase gallium precursor, and/or before the substrate is contacted with the vapor phase zinc precursor.
15. The process of claim 14 , wherein the surface modification agent reacts with OH groups on the substrate surface and wherein the surface modification agent comprises an alcohol or acid anhydride.
16. The process of claim 9 , wherein the substrate is contacted with a dopant precursor comprising a cerium precursor, a tantalum precursor, a silicon precursor, and/or a germanium precursor.
17. An atomic layer deposition (ALD) process for forming an indium gallium zinc oxide (IGZO) channel layer in a transistor device, the ALD process comprising a deposition cycle comprising alternately and sequentially contacting a substrate in a reaction space with a vapor phase indium precursor, a vapor phase gallium precursor, a vapor phase zinc precursor and an oxygen reactant, and repeating the deposition cycle until a IGZO thin film of a desired thickness has been formed, wherein the deposition cycle comprises a zinc oxide sub-cycle that is repeated N1 times and comprises alternately and sequentially contacting the substrate with the zinc precursor and the oxygen reactant; and an indium gallium oxide sub-cycle that is repeated N2 times and comprises alternately and sequentially contacting the substrate with the indium precursor and the gallium precursor and the oxygen reactant, where N is an integer.
18. The process of claim 17 , wherein the gallium precursor comprises at least one amine or alkylamine ligand.
19. The process of claim 17 , wherein the zinc precursor comprises one or more of elemental zinc, a zinc halide, and an alkyl zinc compound.
20. The process of claim 17 , wherein the indium precursor comprises one or more of an indium alkyl, an indium beta diketonate, an indium cyclopentadienyl, and an indium halide.
21. The process of claim 17 , wherein the indium precursor is trimethyl indium, the zinc precursor is diethyl zinc and the gallium precursor is Ga(NMe 2 ) 3 ).
22. The process of claim 21 , wherein the surface modification agent reacts with OH groups on the substrate surface and wherein the surface modification agent comprises an alcohol or acid anhydride.
23. The process of claim 22 , wherein the surface modification agent reacts with OH groups on the substrate surface and wherein the surface modification agent comprises an alcohol or acid anhydride.
24. The process of claim 17 , wherein the substrate is contacted with a dopant precursor comprising a cerium precursor, a tantalum precursor, a silicon precursor, and/or a germanium precursor.