# US 7,744,965 B2 · Method and apparatus for manufacturing a zinc oxide thin film at low temperatures

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- Number: US 7,744,965 B2
- Document ID: US7744965B2
- Status: Granted
- Kind: B2
- Application number: 11/377,204
- Filed: 2006-03-17
- Published: 2007-02-22
- Granted: 2010-06-29
- Earliest claimed: 2005-08-18
- Assignees: Yamanashi University; Yamanashi Prefecture; NAKAYA ltd.
- Inventors: Takashi Matsumoto; Chitake Imazu; Shigeru Hagihara; Kazuhiro Kijima; Osamu Abe; Satoshi Hiraki; Yuichiro Fujikawa
- Web page: https://patentgrep.com/patent/US7744965B2

## CPC

- C23C 14/0026: {Activation or excitation of reactive gases outside the coating chamber}
- C23C 14/086: {of zinc, germanium, cadmium, indium, tin, thallium or bismuth}
- H10P 14/22: using physical deposition, e.g. vacuum deposition or sputtering
- H10P 14/2911: {Arsenides}
- H10P 14/2922: {being non-crystalline insulating materials, e.g. glass or polymers}
- H10P 14/3426: {Oxides}
- H10P 14/3442: {N-type}
- Y10T 428/12667: Oxide of transition metal or Al
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The present invention provides a method and apparatus for forming a zinc oxide thin film with high transparency and high conductivity on a surface of a flexible substrate such as plastic without the indispensable requirement of doping impurities. In the method of forming a zinc oxide thin film by reacting oxygen radicals and zinc atoms on a surface of a substrate placed in a film-forming chamber evacuated to a vacuum, the density of crystal defects that are defects of the atomic arrangement of the zinc oxide thin film is controlled by the temperature of the substrate, and the zinc oxide thin film is thereby formed. It is suitable to form the film while maintaining the temperature of the substrate at 400° C. or less to intentionally disturb the regularity of the atomic arrangement of the zinc oxide thin film.

## Claims

### Claim 1

A method of manufacturing a zinc oxide thin film by reacting oxygen radicals and zinc atoms on a surface of a substrate placed in a film-forming chamber evacuated to a vacuum, wherein the density of crystal defects that are defects of the atomic arrangement of the zinc oxide thin film is controlled by at least a temperature of the substrate, and the zinc oxide thin film is formed,
the density of crystal defects is controlled to within a range of 1×1018 defects/cm3 to 5×1021 defects/cm3, and
wherein the temperature of the substrate is maintained at 400° C. or less by cooling means to form the zinc oxide thin film.

### Claim 2 (depends on 1)

The method of manufacturing a zinc oxide thin film according to claim 1, wherein in reacting the oxygen radicals and the zinc atoms on the surface of the substrate to form the zinc oxide thin film, a dopant is supplied to the surface of the substrate to form the zinc oxide thin film.

### Claim 3 (depends on 2)

The method of manufacturing a zinc oxide thin film according to claim 2, wherein a supply amount of the dopant is controlled so that the ratio of the dopant to the zinc atoms in the zinc oxide thin film is within a range of 1:10 to 1:1000.

### Claim 4 (depends on 1)

The method of manufacturing a zinc oxide thin film according to claim 1, wherein the substrate is a flexible substrate such as plastic.

### Claim 5 (depends on 4)

The method of manufacturing a zinc oxide thin film according to claim 4, wherein the flexible substrate is selected from the group consisting of polyethylene terephthalate (PET), polycarbonate (PC), polyvinyl chloride (PVC) and polypropylene (PP).

### Claim 6 (depends on 1)

The method of manufacturing a zinc oxide thin film according to claim 1, wherein the density of crystal defects in forming the film is controlled by considering the density of crystal defects recovered by a heat treatment process subsequent to formation of the film.