Atomic layer etching
Atomic layer etching (ALE) processes are disclosed. In some embodiments, the methods comprise at least one etch cycle in which a substrate comprising a metal, metal oxide, metal nitride or metal oxynitride layer is contacted with an etch reactant comprising an vapor-phase N-substituted derivative of amine compound. In some embodiments the etch reactant reacts with the substrate surface to form volatile species including metal atoms from the substrate surface. In some embodiments a metal or metal nitride surface is oxidized as part of the ALE cycle. In some embodiments a substrate surface is contacted with a halide as part of the ALE cycle. In some embodiments a substrate surface is contacted with a plasma reactant as part of the ALE cycle.
1. A method of etching a metal, metal oxide or metal nitride on a substrate surface by chemical atomic layer etching in a reaction space, the method comprising one or more etching cycles, each cycle comprising:
contacting the substrate surface with an etch reactant comprising a vapor-phase N-substituted derivative of an amine compound; and
removing excess etch reactant and reaction by-products from the reaction space,
wherein the N-substituted derivative of an amine compound has the formula:
wherein each R1-R6 independently is any alkyl group and each R7 and R8 independently is any of H, methyl, ethyl, isopropyl, n-propyl, tert-butyl, sec-butyl, n-butyl, any isomer of pentyl, any isomer of hexyl, phenyl and fluoro.
2. The method of claim 1 , wherein the metal, metal oxide or metal nitride comprises a metal selected from Co, Ni, Cu, Fe, Mn, Ti, Ta, Hf, Zn, La, Sc, Mo and Cr.
3. The method of claim 1 , wherein the etch cycle is part of a cyclic vapor deposition process.
4. The method of claim 1 , wherein the etch cycle is repeated two or more times in a row.
5. The method of claim 1 , wherein the substrate is a semiconductor substrate.
6. The method of claim 1 , additionally comprising contacting the substrate surface with a vapor-phase second reactant selected from a halide, an oxidant and a plasma reactant.
7. The method of claim 6 , wherein the substrate surface is contacted with the vapor-phase second reactant after being contacted with the etch reactant.
8. The method of claim 1 , wherein the etch cycle comprises:
contacting a metal or metal nitride on the substrate surface with an oxidant to form metal oxide on the substrate surface;
contacting the metal oxide on the substrate surface with the vapor-phase etch reactant comprising an N-substituted derivative of amine compound; and
removing excess etch reactant and reaction by-products from the reaction space.
9. The method of claim 8 , wherein the oxidant comprises O 3 , O 2 , H 2 O, H 2 O 2 , SO 3 , or excited oxygen species.
10. The method of claim 1 , wherein the etch cycle comprises contacting the substrate surface with a plasma to form a plasma-modified surface prior to contacting the substrate surface with the etch reactant.
11. The method of claim 10 , wherein the plasma comprises a plasma generated in a gas comprising hydrogen, nitrogen, a nitrogen-hydrogen mixture, argon, or helium.
12. The method of claim 1 , wherein the etch cycle comprises:
contacting the metal, metal oxide or metal nitride on the substrate surface with a vapor-phase halide reactant to form a halidized surface;
contacting the halidized surface with a vapor-phase etch reactant comprising an N-substituted derivative of amine compound; and
removing excess etch reactant and reaction by-products from the reaction space.
13. The method of claim 12 , wherein prior to contacting the substrate surface with the vapor-phase halide reactant the substrate surface comprises a metal or metal nitride and the metal or metal nitride is contacted with an oxidant to form a metal oxide.
14. The method of claim 12 , wherein the halide reactant comprises a metal halide, a non-metal halide, an organic halide, or an interhalogen.