Electrostatic chuck

• US 10,460,970 B2
• Filed: 02/23/2018
• Issued: 10/29/2019
• Est. Priority Date: 09/30/2015
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Watanabe, Morimichi, Nanataki, Tsutomu
• Primary Examiner(s): Kitov, Zeev V
• Application Number:
  US15/903,175
• Publication Number:
  US 20180190527A1
• Time in Patent Office: 613 Days
• Field of Search: 361234
• CPC Class Codes: B32B 18/00 Layered products essentially comprising ceramics, e.g. refractory products
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/322 Transition aluminas, e.g. delta or gamma aluminas
• CPC Class Codes: C04B 2235/3262 Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/445 Fluoride containing anions, e.g. fluosilicate
• CPC Class Codes: C04B 2235/5292 Flakes, platelets or plates
• CPC Class Codes: C04B 2235/5296 with a defined aspect ratio, e.g. indicating sphericity spherical constituents C04B2235/528
• 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 2235/6025 Tape casting, e.g. with a doctor blade
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2235/6586 Processes characterised by the flow of gas
• CPC Class Codes: C04B 2235/72 Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 2235/786 Micrometer sized grains, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/787 Oriented grains
• CPC Class Codes: C04B 2235/96 Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 2235/963 Surface properties, e.g. surface roughness
• CPC Class Codes: C04B 2237/064 based on alumina or aluminates
• CPC Class Codes: C04B 2237/343 : Alumina or aluminates
• CPC Class Codes: C04B 2237/52 : Pre-treatment of the joining surfaces, e.g. cleaning, machining
• CPC Class Codes: C04B 35/101 : Refractories from grain sized mixtures
• CPC Class Codes: C04B 35/111 : Fine ceramics
• CPC Class Codes: C04B 35/1115 : Minute sintered entities, e.g. sintered abrasive grains or shaped particles such as platelets abrasives C09K3/14
• CPC Class Codes: C04B 35/6262 : of calcined, sintered clinker or ceramics
• CPC Class Codes: C04B 35/6264 : Mixing media, e.g. organic solvents
• CPC Class Codes: C04B 35/6342 : Polyvinylacetals, e.g. polyvinylbutyral [PVB]
• CPC Class Codes: C04B 35/638 : Removal thereof
• CPC Class Codes: C04B 35/64 : Burning or sintering processes C04B33/32 takes precedence ; powder metallurgy B22F
• CPC Class Codes: C04B 35/645 : Pressure sintering
• CPC Class Codes: C04B 37/005 : consisting of glass or ceramic material
• CPC Class Codes: H01L 21/6831 : using electrostatic chucks
• CPC Class Codes: H01L 21/6833 : Details of electrostatic chucks
• CPC Class Codes: H01L 21/68757 : characterised by a coating or a hardness or a material

Abstract

An electrostatic chuck includes a dielectric layer including an oriented alumina sintered body having a degree of c-plane orientation of 5% or more, the degree of c-plane orientation being determined by a Lotgering method using an X-ray diffraction profile obtained by the irradiation of an X-ray in the 2θ range of 20° to 70°; a ceramic layer integrated with a surface disposed opposite a wafer placement surface of the dielectric layer; and an electrostatic electrode between the dielectric layer and the ceramic layer.

Claims

1. An electrostatic chuck comprising:

a dielectric layer including an oriented alumina sintered body having a degree of c-plane orientation of 5% or more, the degree of c-plane orientation being determined by a Lotgering method using an X-ray diffraction profile obtained by the irradiation of an X-ray in the 2θ

range of 20°

to 70°

;

a ceramic layer integrated with a surface disposed opposite a wafer placement surface of the dielectric layer; and

an electrostatic electrode between the dielectric layer and the ceramic layer,

wherein a proportion by volume of pores having a diameter of 0.2 μ

m or more with respect to the volume of the oriented alumina sintered body is 130 ppm or less by volume.

2. The electrostatic chuck according to claim 1, wherein the ceramic layer contains alumina serving as a main component.

3. The electrostatic chuck according to claim 1, wherein the oriented alumina sintered body has a degree of c-plane orientation of 70% or more.

4. The electrostatic chuck according to claim 1, wherein the oriented alumina sintered body has a sintered grain size of 15 to 200 μ

m.

5. The electrostatic chuck according to claim 1, wherein the oriented alumina sintered body has a volume resistivity of 1×

10¹⁷ Ω

cm or more at room temperature and a volume resistivity of 1×

10¹⁵ Ω

cm or more at 200°

C.

6. The electrostatic chuck according to claim 1, wherein a full width at half maximum obtained in an X-ray rocking curve (XRC) measurement of the oriented alumina sintered body is 15°

or less.

7. The electrostatic chuck according to claim 1, wherein a content of an impurity element other than Mg, C, or F in the oriented alumina sintered body is 50 ppm or less.

8. The electrostatic chuck according to claim 1, wherein the oriented alumina sintered body has a content of F of 200 ppm or less by mass.

9. An electrostatic chuck comprising:

a dielectric layer including an oriented alumina sintered body having a degree of c-plane orientation of 5% or more, the degree of c-plane orientation being determined by a Lotgering method using an X-ray diffraction profile obtained by the irradiation of an X-ray in the 2θ

range of 20°

to 70°

;

a ceramic layer integrated with a surface disposed opposite a wafer placement surface of the dielectric layer; and

an electrostatic electrode between the dielectric layer and the ceramic layer,

wherein when an image obtained by capturing a field of view having a length of 370.0 μ

m and a width of 372.0 μ

m with a scanning electron microscope at a magnification of 1,000 is visually observed, the number of foreign objects having a diameter of 0.2 μ

m or more is 50 or less.

10. The electrostatic chuck according to claim 9, wherein the ceramic layer contains alumina serving as a main component.

11. The electrostatic chuck according to claim 9, wherein the oriented alumina sintered body has a degree of c-plane orientation of 70% or more.

12. The electrostatic chuck according to claim 9, wherein the oriented alumina sintered body has a sintered grain size of 15 to 200 μ

m.

13. The electrostatic chuck according to claim 9, wherein the oriented alumina sintered body has a volume resistivity of 1×

10¹⁷ Ω

cm or more at room temperature and a volume resistivity of 1×

10¹⁵ Ω

cm or more at 200°

C.

14. The electrostatic chuck according to claim 9, wherein a full width at half maximum obtained in an X-ray rocking curve (XRC) measurement of the oriented alumina sintered body is 15°

or less.

15. The electrostatic chuck according to claim 9, wherein a content of an impurity element other than Mg, C, or F in the oriented alumina sintered body is 50 ppm or less.

16. The electrostatic chuck according to claim 9, wherein the oriented alumina sintered body has a content of F of 200 ppm or less by mass.