Method for manufacturing sputtering target, method for forming oxide film, and transistor

• US 10,522,347 B2
• Filed: 03/07/2017
• Issued: 12/31/2019
• Est. Priority Date: 02/28/2013
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Tsubuku, Masashi, Oota, Masashi, Kurosawa, Yoichi, Ishihara, Noritaka
• Primary Examiner(s): Nguyen, Khanh T
• Application Number:
  US15/451,715
• Publication Number:
  US 20170178904A1
• Time in Patent Office: 1,029 Days
• Field of Search: 252500, 349 43
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01G 15/006 Compounds containing, besides gallium, indium, or thallium, two or more other elements, with the exception of oxygen or hydrogen
• CPC Class Codes: C01P 2002/32 spinel-type (AB2O4)
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2002/85 by XPS, EDX or EDAX data
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C23C 14/08 Oxides C23C14/10 takes precedence
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: C23C 14/3414 Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• CPC Class Codes: C30B 1/04 Isothermal recrystallisation
• CPC Class Codes: C30B 23/08 by condensing ionised vapours by reactive sputtering C30B25/06
• CPC Class Codes: C30B 28/02 directly from the solid state
• CPC Class Codes: C30B 29/22 Complex oxides
• CPC Class Codes: C30B 29/68 Crystals with laminate structure, e.g. "superlattices"
• CPC Class Codes: H01J 2237/081 Sputtering sources
• CPC Class Codes: H01J 2237/3322 Problems associated with coating
• CPC Class Codes: H01J 2237/3323 uniformity
• CPC Class Codes: H01J 37/3429 : Plural materials
• CPC Class Codes: H01L 21/02565 : Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02609 : Crystal orientation
• CPC Class Codes: H01L 21/02631 : Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 29/045 : by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/24 : including, apart from doping materials or other impurities, only semiconductor materials not provided for in groups H01L29/16, H01L29/18, H01L29/20, H01L29/22 including organic materials H10K99/00
• CPC Class Codes: H01L 29/66969 : of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/7869 : having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78696 : characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

A method for manufacturing a sputtering target with which an oxide semiconductor film with a small amount of defects can be formed is provided. Alternatively, an oxide semiconductor film with a small amount of defects is formed. A method for manufacturing a sputtering target is provided, which includes the steps of: forming a polycrystalline In-M-Zn oxide (M represents a metal chosen among aluminum, titanium, gallium, yttrium, zirconium, lanthanum, cesium, neodymium, and hafnium) powder by mixing, sintering, and grinding indium oxide, an oxide of the metal, and zinc oxide; forming a mixture by mixing the polycrystalline In-M-Zn oxide powder and a zinc oxide powder; forming a compact by compacting the mixture; and sintering the compact.

Claims

1. A method for manufacturing a semiconductor device, comprising the steps of:

forming a gate electrode;

forming a first oxide film by using a first sputtering target comprising In, Ga and Zn over the gate electrode;

forming a second oxide film by using a second sputtering target comprising In, Ga and Zn over the first oxide film; and

forming a source electrode and a drain electrode over the second oxide film,

wherein the first oxide film comprises a microcrystal,

wherein the second oxide film comprises a c-axis aligned crystal part, and

wherein an atomic ratio of metal elements of the second sputtering target satisfies Ga>

In and Zn>

Ga.

2. The method for manufacturing a semiconductor device according to claim 1, wherein an atomic ratio of metal elements of the first sputtering target satisfies In:

Ga;

Zn=1;

1;

1.

3. The method for manufacturing a semiconductor device according to claim 1, wherein the c-axis of the second oxide film is aligned in a direction parallel to a normal vector of a surface where the second oxide film is formed or a top surface of the second oxide film.

4. The method for manufacturing a semiconductor device according to claim 1,

wherein a direction of an a-axis of a first region of the second oxide film is different from a direction of an a-axis of a second region of the second oxide film, and

wherein a direction of a b-axis of the first region of the second oxide film is different from a direction of a b-axis of the second region of the second oxide film.

5. The method for manufacturing a semiconductor device according to claim 1, wherein an electron diffraction pattern of the second oxide film shows a plurality of bright spots.

6. The method for manufacturing a semiconductor device according to claim 1,

wherein an atomic ratio of Ga to In and an atomic ratio of Zn to In in the first oxide film are lower than those in the first sputtering target, and

wherein an atomic ratio of Ga to In and an atomic ratio of Zn to In in the second oxide film are lower than those in the second sputtering target.

7. A method for manufacturing a semiconductor device, comprising the steps of:

forming a gate electrode;

forming a first oxide film by using a first sputtering target comprising In, Ga and Zn over the gate electrode;

forming a second oxide film by using a second sputtering target comprising In, Ga and Zn over the first oxide film; and

forming a source electrode and a drain electrode over the second oxide film,

wherein the first oxide film comprises a microcrystal,

wherein the second oxide film comprises a c-axis aligned crystal part,

wherein an atomic ratio of metal elements of the first sputtering target satisfies In ≥

Ga and Zn≥

Ga, and

wherein an atomic ratio of metal elements of the second sputtering target satisfies Ga>

In and Zn>

Ga.

8. The method for manufacturing a semiconductor device according to claim 7, wherein an atomic ratio of metal elements of the first sputtering target satisfies In:

Ga;

Zn=1;

1;

1.

9. The method for manufacturing a semiconductor device according to claim 7, wherein the c-axis of the second oxide film is aligned in a direction parallel to a normal vector of a surface where the second oxide film is formed or a top surface of the second oxide film.

10. The method for manufacturing a semiconductor device according to claim 7,

wherein a direction of an a-axis of a first region of the second oxide film is different from a direction of an a-axis of a second region of the second oxide film, and

wherein a direction of a b-axis of the first region of the second oxide film is different from a direction of a b-axis of the second region of the second oxide film.

11. The method for manufacturing a semiconductor device according to claim 7,

wherein the second oxide film comprises a first crystal part and a second crystal part,

wherein a direction of a c-axis of the first crystal part is parallel to a direction of a c-axis of the second crystal part,

wherein a direction of an a-axis of the first crystal part is different from a direction of an a-axis of the second crystal part, and

wherein a direction of a b-axis of the first crystal part is different from a direction of a b-axis of the second crystal part.

12. The method for manufacturing a semiconductor device according to claim 7,

wherein an atomic ratio of Ga to In and an atomic ratio of Zn to In in the first oxide film are lower than those in the first sputtering target, and

wherein an atomic ratio of Ga to In and an atomic ratio of Zn to In in the second oxide film are lower than those in the second sputtering target.

13. The method for manufacturing a semiconductor device according to claim 7, wherein a size of the c-axis aligned crystal part in the second oxide film is greater than or equal to 1 nm and less than or equal to 100 nm.

14. A method for manufacturing a semiconductor device,

forming a gate electrode;

forming a first oxide film by using a first sputtering target comprising In, Ga and Zn over the gate electrode;

forming a second oxide film by using a second sputtering target comprising In, Ga and Zn over the first oxide film; and

forming a source electrode and a drain electrode over the second oxide film,

wherein the first oxide film comprises a microcrystal,

wherein the second oxide film comprises a c-axis aligned crystal part,

wherein an atomic ratio of Ga to In in the second sputtering target is higher than an atomic ratio of Ga to In in the first sputtering target, and

wherein an atomic ratio of In to Zn in the second sputtering target is higher than an atomic ratio of In to Zn in the first sputtering target.

15. The method for manufacturing a semiconductor device according to claim 14, wherein an atomic ratio of metal elements of the first sputtering target satisfies In:

Ga;

Zn=1;

1;

1.

16. The method for manufacturing a semiconductor device according to claim 14, wherein the c-axis of the second oxide film is aligned in a direction parallel to a normal vector of a surface where the second oxide film is formed or a top surface of the second oxide film.

17. The method for manufacturing a semiconductor device according to claim 14, wherein a direction of an a-axis of a first region of the second oxide film is different from a direction of a second region of the second oxide film.

18. The method for manufacturing a semiconductor device according to claim 14,

wherein the second oxide film comprises a first crystal part and a second crystal part,

wherein a direction of a c-axis of the first crystal part is parallel to a direction of a c-axis of the second crystal part,

wherein a direction of an a-axis of the first crystal part is different from a direction of an a-axis of the second crystal part, and

wherein a direction of a b-axis of the first crystal part is different from a direction of a b-axis of the second crystal part.

19. The method for manufacturing a semiconductor device according to claim 14,

wherein an atomic ratio of Ga to In and an atomic ratio of Zn to In in the first oxide film are lower than those in the first sputtering target, and

wherein an atomic ratio of Ga to In and an atomic ratio of Zn to In in the second oxide film are lower than those in the second sputtering target.

20. The method for manufacturing a semiconductor device according to claim 14, wherein a size of the c-axis aligned crystal part in the second oxide film is greater than or equal to 1 nm and less than or equal to 100 nm.