Sputtering Target and Oxide Semiconductor Film

• US 20100108502A1
• Filed: 11/30/2007
• Published: 05/06/2010
• Est. Priority Date: 12/13/2006
• Status: Active Grant

• Current Assignee: Idemitsu Kosan Company Limited
• Original Assignee: Idemitsu Kosan Company Limited
• Inventors: Inoue, Kazuyoshi, Utsuno, Futoshi, Yano, Koki
• Granted Patent: US 8,784,700 B2
• Time in Patent Office: Days
• US Class Current: 204/298.130
• CPC Class Codes: C01G 15/00 Compounds of gallium, indium or thallium
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3244 Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3251 Niobium oxides, niobates, tantalum oxides, tantalates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3256 Molybdenum oxides, molybdates or oxide forming salts thereof, e.g. cadmium molybdate
• CPC Class Codes: C04B 2235/3258 Tungsten oxides, tungstates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3284 Zinc oxides, zincates, cadmium oxides, cadmiates, mercury oxides, mercurates or oxide forming salts thereof
• CPC Class Codes: C04B 2235/3286 Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate
• CPC Class Codes: C04B 2235/3287 Germanium oxides, germanates or oxide forming salts thereof, e.g. copper germanate
• CPC Class Codes: C04B 2235/3293 Tin oxides, stannates or oxide forming salts thereof, e.g. indium tin oxide [ITO]
• CPC Class Codes: C04B 2235/5409 expressed by specific surface values
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5445 submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/604 Pressing at temperatures other than sintering temperatures
• CPC Class Codes: C04B 2235/6585 at an oxygen percentage above that of air
• CPC Class Codes: C04B 2235/6586 Processes characterised by the flow of gas
• CPC Class Codes: C04B 2235/725 Metal content
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 35/01 based on oxide ceramics
• CPC Class Codes: C04B 35/453 : based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
• CPC Class Codes: C04B 35/6261 : Milling
• CPC Class Codes: C04B 35/62625 : Wet mixtures
• CPC Class Codes: C04B 35/62655 : Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• 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: H01J 2237/332 : Coating
• 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 21/02631 : Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation

Abstract

A sputtering target containing oxides of indium (In), gallium (Ga) and zinc (Zn), which includes a compound shown by ZnGa₂O₄ and a compound shown by InGaZnO₄.

Claims

1. A sputtering target containing oxides of indium (In), gallium (Ga) and zinc (Zn), which comprises a compound shown by ZnGa₂O₄ and a compound shown by InGaZnO₄.

2. The sputtering target according to claim 1, which comprises a homologous structure compound shown by InGaO₃(ZnO)_m wherein m is an integer of 1 to 20 and a spinel structure compound shown by ZnGa₂O₄.

3. The sputtering target according to claim 1, wherein an atomic ratio shown by In/(In+Ga+Zn), an atomic ratio shown by Ga/(In+Ga+Zn) and an atomic ratio shown by Zn/(In+Ga+Zn) satisfy the following relationship:

0.2<

In/(In+Ga+Zn)<

0.77

0.2<

Ga/(In+Ga+Zn)<

0.50

0.03<

Zn/(In+Ga+Zn)<

0.50

4. The sputtering target according to claim 1, wherein the atomic ratio shown by In/(In+Ga+Zn) and the atomic ratio shown by Ga/(In+Ga+Zn) satisfy the following relationship:

In/(In+Ga+Zn)>

Ga/(In+Ga+Zn)

5. The sputtering target according to claim 1, wherein the sputtering target comprises a metal element with an atomic valency of positive tetravalency or higher, and the atomic ratio of the metal element with an atomic valency of positive tetravalency or higher relative to the total metal elements is 0.0001 to 0.2.

6. The sputtering target according to claim 5, wherein the metal element with an atomic valency of positive tetravalency or higher is one or more elements selected from tin, zirconium, germanium, cerium, niobium, tantalum, molybdenum and tungsten.

7. The sputtering target according to claim 1, which has a bulk resistance of less than 5×

10<sup>−

3</sup> Ω

cm.

8. The sputtering target according to claim 2, wherein the average diameter of the spinel structure compound shown by ZnGa₂O₄ is 10 μ

m or less.

9. The sputtering target according to claim 1, which has a sintered body density of 6.0 g/cm³ or more.

10. The sputtering target according to claim 1, which has a surface roughness (Ra) of 2 μ

m or less and an average transverse rupture strength of 50 MPa or more.

11. The sputtering target according to claim 1, wherein the content of each of Fe, Al, Si, Ni and Cu is 10 ppm (weight) or less.

12. A method for producing the sputtering target according to claim 1 comprising:

pulverizing and mixing/granulating indium oxide, gallium oxide and zinc oxide to prepare a mixture;

molding the mixture to prepare a molded product; and

firing the molded product in an oxygen stream or under oxygen pressure at a temperature of 1250°

C. or higher and lower than 1450°

C.

13. An oxide semiconductor film obtained by sputtering the sputtering target according to claim 1.

14. A sputtering target comprising a compound shown by InGaZnO₄ as a main component, which further contains a metal element with an atomic valency of positive tetravalency or higher.

15. The sputtering target according to claim 14, wherein the content of the metal element with an atomic valency of positive tetravalency or higher is 100 ppm to 10000 ppm relative to the total metal elements in the sputtering target.

16. The sputtering target according to claim 14, wherein the content of the metal element with an atomic valency of positive tetravalency or higher is 200 ppm to 5000 ppm relative to the total metal elements in the sputtering target.

17. The sputtering target according to claim 14, wherein the content of the metal element with an atomic valency of positive tetravalency or higher is 500 ppm to 2000 ppm relative to the total metal elements in the sputtering target.

18. The sputtering target according to claim 14, which has a bulk resistance of less than 1×

10<sup>−

3</sup> Ω

cm.

19. The sputtering target according to claim 14, wherein the metal element with an atomic valency of positive tetravalency or higher is at least one element selected from the group consisting of tin, zirconium, germanium, cerium, niobium, tantalum, molybdenum and tungsten.

20. A method for producing a sputtering target comprising the steps of:

preparing, as raw material powder, mixed powder containing indium oxide powder having a specific surface area of 6 to 10 m²/g, gallium oxide powder having a specific surface area of 5 to 10 m²/g and zinc oxide powder having a surface area of 2 to 4 m²/g, the specific surface area of the entire mixed powder being 5 to 8 m²/g;

mixing/pulverizing the raw material powder by means of a wet medium stirring mill to increase the specific surface area of the entire mixed powder by 1.0 to 3.0 m²/g;

molding the raw material powder to obtain a molded product; and

sintering the molded product in an oxygen atmosphere at a temperature of 1250 to 1450°

C.

22. The method for producing a sputtering target according to claim 20, wherein the sintering is performed without conducting prefiring.

23. The method for producing a sputtering target according to claim 20, wherein the density of a sintered body obtained in the sintering step is 6.0 g/cm³ or more.

21. A method for producing a sputtering target comprising the steps of:

preparing, as raw material powder, mixed powder containing indium oxide powder having a median diameter of particle size distribution of 1 to 2 μ

m, gallium oxide powder having a median diameter of particle size distribution of 1 to 2 μ

m and zinc oxide powder having a median diameter of particle size distribution of 0.8 to 1.6 μ

m, the median diameter of particle size distribution of the entire mixed powder being 1.0 to 1.9 μ

m;

mixing/pulverizing the raw material powder by means of a wet medium stirring mill to allow the raw material powder to have a median diameter of 0.6 to 1 μ

m;

molding the raw material powder to obtain a molded product; and

sintering the molded product in an oxygen atmosphere at a temperature of 1250 to 1450°

C.