Mullite sintered body, method for producing the same, and composite substrate

Patent metadata

Field	Value
Publication number	US-9776924-B2
Application number	US-201615064968-A
Country	US
Kind code	B2
Filing date	Mar 9, 2016
Priority date	Jun 6, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

A mullite sintered body according to the present invention has an impurity element content of 1% by mass or less and contains sintered mullite grains having an average grain size of 8 μm or less. When a surface of the mullite sintered body is finished by polishing, pores in the surface have an average largest pore length of 0.4 μm or less. The surface preferably has a center line average surface roughness (Ra) of 3 nm or less. The surface preferably has a maximum peak height (Rp) of 30 nm or less. The number of pores in the surface is preferably 10 or less per unit area of 4 μm×4 μm.

First claim

What is claimed is:

1. A composite substrate comprising:
a support substrate; and
a functional substrate bonded to the support substrate,
wherein the support substrate is a mullite sintered body having an impurity element content of 1% by mass or less, the mullite sintered body containing sintered mullite grains having an average grain size of 8 μm or less, wherein pores present in a polished surface thereof have an average largest pore length of 0.4 μm or less, the mullite sintered body has a porosity of less than 0.03%, and the maximum peak height (Rp) of the surface of the mullite sintered body is 30 nm or less, and
wherein when the mullite sintered body is formed into a plate having a thickness of 0.1 mm, the plate has a total light transmittance of 20% or more to light having a wavelength of 550 nm.

2. The composite substrate according to claim 1 , wherein the surface of the mullite sintered body has a center line average surface roughness (Ra) of 3 nm or less.

3. The composite substrate according to claim 1 , wherein the number of pores in the surface of the mullite sintered body is 10 or less per unit area of 4 μm×4 μm.

4. The composite substrate according to claim 1 , wherein the mullite sintered body has a 4-point flexural strength of 280 MPa or more.

5. The composite substrate according to claim 1 , wherein the impurity element content of the mullite sintered body is 0.5% by mass or less.

6. The composite substrate according to claim 1 , wherein the functional substrate is directly bonded to the support substrate.

7. The composite substrate according to claim 1 , wherein the mullite sintered body has a bulk density of 3.15 g/cm 3 .

Assignees

• Ngk Insulators Ltd

Inventors

• Isoda Yoshinori
• Sato Yosuke
• Katsuda Yuji

Classifications

• C04B2235/5436

  micrometer sized, i.e. from 1 to 100 micron · CPC title

• C04B2235/785

  Submicron sized grains, i.e. from 0,1 to 1 micron · CPC title

• C04B2237/55

  Pre-treatments of a coated or not coated substrate other than oxidation treatment in order to form an active joining layer · CPC title

• C04B2237/34

  Oxidic · CPC title

• C04B2235/6586

  Processes characterised by the flow of gas · CPC title