Method in depositing metal oxide materials
The present invention relates to a method for enhancing uniformity of metal oxide coatings formed by Atomic Layer Deposition (ALD) or ALD-type processes. Layers are formed using alternating pulses of metal halide and oxygen-containing precursors, preferably water, and purging when necessary. An introduction of modificator pulses following the pulses of the oxygen-containing precursor affects positively on layer uniformity, which commonly exhibits gradients, particularly in applications with closely arranged substrates. In particular, improvement in layer thickness uniformity is obtained. According to the invention, alcohols having one to three carbon atoms can be used as the modificator.
1. A method for reducing or eliminating layer non-uniformity in an ALD or ALD-type process for depositing a metal oxide film, the method comprising the following phases:
a) exposing a surface to a first precursor or precursor mixture comprising at least one metal halide,
b) exposing the resulting surface to a second precursor selected from the group consisting of water, hydrogen peroxide, tert-butanol and mixtures of these,
c) exposing the resulting surface to at least one modificator comprising a chemical substance selected from the group consisting of alcohols having one to three carbon atoms,
wherein steps (a), (b), and (c) provide a metal oxide film that is deposited on the surface.
2. A method according to claim 1 , comprising the repetition of phases b-c at least once.
3. A method according to claim 1 , comprising repetition of phases a-c at least once.
4. A method according to claim 3 , comprising at least one cycle of phases a and b without phase c.
5. A method according to claim 1 , wherein phases a) and/or b) comprises the use of several of the precursors in succession.
6. A method according to claim 1 , wherein the modificator is methanol, ethanol or n-propanol.
7. A method according to claim 1 , wherein said non-uniformity reduction relates to non-uniformity of physical layer thickness.
8. A method according to claim 1 , wherein said non-uniformity reduction relates to non-uniformity in crystallinity.
9. A method according to claim 1 , wherein an oxide of Ta, Ti, Al, Hf, Zr, or Nb, or a combination of these oxides is deposited.
10. A method according to claim 1 , wherein the first precursor is selected from the group consisting of tantalum chloride, titanium chloride, aluminium chloride, hafnium chloride, zirconium chloride and niobium chloride and mixtures of these.
11. A method according to claim 1 , further comprising at least one purging operation.
12. A method according to claim 1 , wherein a dose of second precursor and a dose of modificator overlap, fully or partially.
13. A method according to claim 1 , wherein the phases are implemented in a coating application, where two or more surfaces are coated and the distance between the surfaces to be coated is <12 mm.
14. A method according to claim 1 , wherein the phases are implemented in a coating application, where two or more surfaces are coated and the distance between the surfaces to be coated is <1 micrometer.
15. A method according to claim 1 , wherein the phases are performed in an ALD reactor.
16. A method according to claim 1 , wherein the phases are performed for depositing an optical film or a film stack.
17. The method according to claim 16 , wherein the film stack contains titanium oxide and silicon oxide, titanium oxide and aluminium oxide, or titanium oxide, aluminium oxide and silicon oxide.
18. The method according to claim 16 , wherein the surface where the optical film is deposited is a glass substrate.
19. A method according to claim 1 , wherein the phases are performed for depositing a dielectric film or a film stack.
20. The method according to claim 19 , wherein the film stack contains at least one of titanium oxide, aluminium oxide, hafnium oxide, zirconium oxide, tantalum oxide, and niobium oxide.
21. The method according to claim 20 , wherein the surface where the dielectric film is deposited is a silicon wafer or a structure made on a silicon wafer.
22. A method according to claim 1 , wherein the surface is an inner surface of a tubular structure.