Aluminum nitride sintered product, method for producing the same, and electrostatic chuck including the same

• US 8,022,001 B2
• Filed: 11/16/2009
• Issued: 09/20/2011
• Est. Priority Date: 11/21/2008
• Status: Active Grant

• Current Assignee: NGK Insulators Limited
• Original Assignee: NGK Insulators Limited
• Inventors: Hayase, Toru, Teratani, Naomi, Katsuda, Yuji
• Primary Examiner(s): GROUP, KARL E
• Application Number:
  US12/618,901
• Publication Number:
  US 20100128409A1
• Time in Patent Office: 673 Days
• Field of Search: 501/98.4, 501/98.6
• US Class Current: 501/98.4
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• CPC Class Codes: C04B 2235/3222 Aluminates other than alumino-silicates, e.g. spinel (MgAl2O4)
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3865 Aluminium nitrides
• CPC Class Codes: C04B 2235/3886 Refractory metal nitrides, e.g. vanadium nitride, tungsten nitride
• CPC Class Codes: C04B 2235/3895 Non-oxides with a defined oxygen content, e.g. SiOC, TiON
• 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 2235/656 characterised by specific heating conditions during heat treatment
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2235/6581 Total pressure below 1 atmosphere, e.g. vacuum
• CPC Class Codes: C04B 2235/661 Multi-step sintering
• 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 2235/85 Intergranular or grain boundary phases
• CPC Class Codes: C04B 2235/9607 Thermal properties, e.g. thermal expansion coefficient
• CPC Class Codes: C04B 35/581 based on aluminium nitride
• CPC Class Codes: C04B 35/62655 Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 35/645 Pressure sintering
• CPC Class Codes: H01L 21/6833 : Details of electrostatic chucks

Abstract

A method for producing an aluminum nitride sintered product according to the present invention includes the steps of (a) preparing a powder mixture that contains AlN, 2 to 10 parts by weight of Eu₂O₃ with respect to 100 parts by weight of AlN, Al₂O₃ such that a molar ratio of Al₂O₃ to Eu₂O₃ is 2 to 10, and TiO₂ such that a molar ratio of TiO₂ to Al₂O₃ is 0.05 to 1.2, but not Sm; (b) producing a compact from the powder mixture; and (c) firing the compact by subjecting the compact to hot-press firing in a vacuum or in an inert atmosphere.

Claims

1. A method for producing an aluminum nitride sintered product comprising the steps of:

(a) preparing a powder mixture that contains aluminum nitride, 2 to 10 parts by weight of europium oxide with respect to 100 parts by weight of aluminum nitride, aluminum oxide such that a molar ratio of aluminum oxide to europium oxide is 2 to 10, and titanium oxide such that a molar ratio of titanium oxide to aluminum oxide is 0.05 to 1.2, but not a samarium compound;

(b) producing a compact from the powder mixture; and

(c) firing the compact by (1) subjecting the compact to hot-press firing in a vacuum or in an inert atmosphere or (2) subjecting the compact to hot-press firing in a vacuum or in an inert atmosphere and subsequently to an annealing treatment at a temperature higher than a temperature in the firing.

2. The method for producing an aluminum nitride sintered product according to claim 1,

wherein, in the step (a) of preparing the powder mixture, 3 to 5 parts by weight of europium oxide is used with respect to 100 parts by weight of aluminum nitride.

3. An aluminum nitride sintered product produced by the method for producing an aluminum nitride sintered product according to claim 1.

4. An aluminum nitride sintered product according to claim 3,

wherein the aluminum nitride sintered product contains aluminum nitride as a main component;

includes a continuous grain boundary phase having peaks corresponding to EuAl₁₂O₁₉ and a crystal phase having peaks corresponding to TiN, but not a crystal phase containing Sm;

has a volume resistivity of 1×

10¹²Ω

·

cm or less at 500 V/mm at room temperature; and

has an activation energy (Ea) of 0.5 eV or less, the activation energy being obtained on the basis of a variation in volume resistivity from room temperature to 300°

C.

6. An electrostatic chuck produced with the aluminum nitride sintered product according to claim 3.

7. An electrostatic chuck produced with the aluminum nitride sintered product according to claim 4.

5. An aluminum nitride sintered product that contains aluminum nitride as a main component;

includes a continuous grain boundary phase having peaks corresponding to EuAl₁₂O₁₉ and a crystal phase having peaks corresponding to TiN, but not a crystal phase containing Sm;

has a volume resistivity of 1×

10¹²Ω

·

cm or less at 500 V/mm at room temperature; and

has an activation energy (Ea) of 0.5 eV or less, the activation energy being obtained on the basis of a variation in volume resistivity from room temperature to 300°

C.

8. An electrostatic chuck produced with the aluminum nitride sintered product according to claim 5.