Alumina-sintered body and associated manufacturing method, and electrostatic chuck and associated manufacturing method

• US 20060205585A1
• Filed: 03/08/2006
• Published: 09/14/2006
• Est. Priority Date: 03/11/2005
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Mori, Yutaka, Nobori, Kazuhiro, Matsuda, Hiroto
• Granted Patent: US 7,387,977 B2
• Time in Patent Office: Days
• US Class Current: 501/127
• CPC Class Codes: C04B 2235/5418 expressed by the size of the particles or aggregates thereof
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/604 Pressing at temperatures other than sintering temperatures
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/6565 Cooling rate
• CPC Class Codes: C04B 2235/658 Atmosphere during thermal treatment
• CPC Class Codes: C04B 2235/661 Multi-step sintering
• 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 2235/721 Carbon content
• 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 35/111 Fine ceramics
• CPC Class Codes: C04B 35/62655 Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 35/62695 Granulation or pelletising devices for shaping artificial aggregates from ceramic mixtures B28B1/004
• CPC Class Codes: C04B 35/632 Organic additives
• CPC Class Codes: C04B 35/63416 Polyvinylalcohols [PVA]; Polyvinylacetates
• CPC Class Codes: C04B 35/645 Pressure sintering
• CPC Class Codes: H01L 21/6833 Details of electrostatic chucks
• CPC Class Codes: H02N 13/00 Clutches or holding devices using electrostatic attraction, e.g. using Johnson-Rahbek effect
• CPC Class Codes: Y10T 279/23 with magnetic or electrostatic means

Abstract

A binder is mixed to alumina powder with a purity of 99.5% or more (step S11), the mixture is granulated (step S12), resultant granule powder is formed with a die (step S13), and a formed compact is sintered in a hot-pressing manner (step S14).

Claims

1. An alumina-sintered body obtained by mixing a binder to alumina powder with a purity of 99.5% or more to prepare granulated powder, forming a compact of the granulated powder with a metallic die, and performing a hot-press sintering of the compact, whereby the alumina-sintered body contains 0.05% to 0.5% by weight residual carbon, and has a four-point bending strength of 500 MPa or more.

2. The alumina-sintered body as claimed in claim 1, having a volume resistivity of 10¹⁵Ω

·

cm or more.

3. The alumina-sintered body as claimed in claim 1, wherein the granulated powder is prepared by a spray drying method.

4. The alumina sintered body as claimed in claim 1, wherein size of crystal grains in the alumina sintered body is 1 to 3 μ

m.

8. An electrostatic chuck, comprising:

a first alumina sintered body;

an electrode formed on an outer surface of the first alumina sintered body by screen printing; and

a second alumina sintered body formed on the electrode and the outer surface with the electrode formed thereon by hot-press sintering of alumina granulated powder obtained by mixing alumina powder and a binder, the second alumina sintered body covering the electrode and having the electrode embedded therein, wherein

the first alumina sintered body is the alumina sintered body as claimed in claim 1.

5. A manufacturing method of alumina-sintered body, comprising the steps of:

mixing a binder to alumina powder with a purity of 99.5% or more to prepare granulated powder;

forming a compact of the granulated powder with a metallic die; and

performing a hot-press sintering of the compact.

6. The method of manufacturing an alumina sintered body as claimed in claim 5, wherein the binder is polyvinyl alcohol and an amount of the binder added is 1.1 to 11 wt %.

7. The manufacturing method as claimed in claim 5, wherein the granulated powder is prepared by a spray drying method.

9. A method of manufacturing an electrostatic chuck, comprising the steps of:

forming an electrode on an outer surface of a first alumina sintered body by screen printing; and

forming a second alumina sintered body on the electrode and the outer surface with the electrode formed thereon by hot-press sintering of alumina granulated powder obtained by mixing alumina powder and a binder, the second alumina sintered body covering the electrode and having the electrode embedded therein, wherein

the first alumina sintered body is manufactured by the method as claimed in claim 5.