# US 10,308,560 B2 · High thermal conductive silicon nitride sintered body, and silicon nitride substrate and silicon nitride circuit board and semiconductor apparatus using the same

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- Number: US 10,308,560 B2
- Document ID: US10308560B2
- Status: Granted
- Kind: B2
- Application number: 15/545,586
- Filed: 2016-01-19
- Published: 2018-01-04
- Granted: 2019-06-04
- Earliest claimed: 2015-01-23
- Assignees: Kabushiki Kaisha Toshiba; Toshiba Materials Co., Ltd.
- Applicants: Kabushiki Kaisha Toshiba; Toshiba Materials Co., Ltd.
- Inventors: Katsuyuki Aoki
- Web page: https://patentgrep.com/patent/US10308560B2

## CPC

- C04B 35/584: based on silicon nitride
- C04B 37/026: {consisting of metals or metal salts}
- H05K 1/03: Use of materials for the substrate
- H05K 1/05: Insulated {conductive substrates, e.g. insulated} metal substrate
- H10W 40/10: Arrangements for heating
- H10W 40/255: {having a laminate or multilayered structure, e.g. direct bond copper [DBC] ceramic substrates}
- H10W 70/60: Insulating or insulated package substrates; Interposers; Redistribution layers (leadframes H10W70/40)
- H10W 70/68: Shapes or dispositions thereof
- H10W 70/692: Ceramics or glasses
- C04B 2235/3205: Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
- C04B 2235/3206: Magnesium oxides or oxide-forming salts thereof
- C04B 2235/3208: Calcium oxide or oxide-forming salts thereof, e.g. lime
- C04B 2235/3224: Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
- C04B 2235/3225: Yttrium oxide or oxide-forming salts thereof
- C04B 2235/3232: Titanium oxides or titanates, e.g. rutile or anatase
- C04B 2235/3244: Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
- C04B 2235/3248: Zirconates or hafnates, e.g. zircon
- C04B 2235/3249: containing also titanium oxide or titanates, e.g. lead zirconate titanate (PZT)
- C04B 2235/3878: Alpha silicon nitrides
- C04B 2235/3895: Non-oxides with a defined oxygen content, e.g. SiOC, TiON
- C04B 2235/5436: micrometer sized, i.e. from 1 to 100 micron
- C04B 2235/5445: submicron sized, i.e. from 0,1 to 1 micron
- C04B 2235/6562: Heating rate
- C04B 2235/6565: Cooling rate
- C04B 2235/6567: Treatment time
- C04B 2235/767: Hexagonal symmetry, e.g. beta-Si3N4, beta-Sialon, alpha-SiC or hexa-ferrites
- C04B 2235/77: Density
- C04B 2235/786: Micrometer sized grains, i.e. from 1 to 100 micron
- C04B 2235/80: Phases present in the sintered or melt-cast ceramic products other than the main phase
- C04B 2235/85: Intergranular or grain boundary phases
- C04B 2235/96: Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
- C04B 2235/9607: Thermal properties, e.g. thermal expansion coefficient
- C04B 2235/963: Surface properties, e.g. surface roughness
- C04B 2237/125: based on noble metals, e.g. silver
- C04B 2237/127: The active component for bonding being a refractory metal
- C04B 2237/368: Silicon nitride
- C04B 2237/407: Copper
- C04B 2237/704: of one or more of the ceramic layers or articles
- C04B 2237/706: of one or more of the metallic layers or articles
- C04B 2237/86: Joining of two substrates at their largest surfaces, one surface being complete joined and covered, the other surface not, e.g. a small plate joined at it's largest surface on top of a larger plate
- H05K 1/0306: {Inorganic insulating substrates, e.g. ceramic, glass}
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

The present invention provides a high thermal conductive silicon nitride sintered body having a thermal conductivity of 50 W/m·K or more and a three-point bending strength of 600 MPa or more, wherein when an arbitrary cross section of the silicon nitride sintered body is subjected to XRD analysis and highest peak intensities detected at diffraction angles of 29.3±0.2°, 29.7±0.2°, 27.0±0.2°, and 36.1±0.2° are expressed as I29.3°, I29.7°, I27.0°, and I36.1°, a peak ratio (I29.3°)/(I27.0°+I36.1°) satisfies a range of 0.01 to 0.08, and a peak ratio (I29.7°)/(I27.0°+I36.1°) satisfies a range of 0.02 to 0.16. Due to above configuration, there can be provided a silicon nitride sintered body having a high thermal conductivity of 50 W/m·K or more, and excellence in insulating properties and strength.

## Claims

### Claim 1

A high thermal conductive silicon nitride sintered body having a thermal conductivity of 50 W/m·K or more and a three-point bending strength of 600 MPa or more,
wherein highest peak intensities detected at diffraction angles of 29.3±0.2°, 29.7±0.2°, 27.0±0.2°, and 36.1±0.2° are expressed as I29.3°, I29.7°, I27.0°, and I36.1°, respectively, the highest peak intensities being detected by XRD analysis for an arbitrary cross section of the silicon nitride sintered body, whereby a peak ratio (I29.3°)/(I27.0°+I36.1°) satisfies a range of 0.01 to 0.08, and a peak ratio (I29.7°)/(I27.0°+I36.1°) satisfies a range of 0.02 to 0.16, and
the I29.3° and I29.7° correspond to peaks depending on a rare earth element-hafnium-oxygen compound crystal.

### Claim 2 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein the I27.0° and I36.1° correspond to peaks depending on a β-Si3N4 crystal.

### Claim 3 (depends on 2)

The high thermal conductive silicon nitride sintered body according to claim 2, wherein the rare earth element-hafnium-oxygen compound crystal comprises two or more types of compound crystals having same constituent elements and different composition ratios.

### Claim 4 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein a sum of the peak ratio (I29.3°)/(I27.0°+I36.1°) and the peak ratio (I29.7°)/(I27.0°+I36.1°) satisfies a range of 0.03 to 0.20.

### Claim 5 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein when a highest peak intensity detected at 34.8±0.2° is expressed as I34.8°, a peak ratio (I34.8°)/(I27.0°+I36.1°) is 0.02 or less (including zero).

### Claim 6 (depends on 2)

The high thermal conductive silicon nitride sintered body according to claim 2, wherein the rare earth element-hafnium-oxygen compound crystal comprises two or more types selected from a Y1.6Hf0.3O3 crystal, a Y0.5Hf0.5O1.75 crystal, and a Y0.1Hf0.9O1.95 crystal.

### Claim 7 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, comprising yttrium.

### Claim 8 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein a maximum diameter of a grain boundary phase is 10 μm or less in an arbitrary cross section of the silicon nitride sintered body.

### Claim 9 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein an average particle diameter of major axes of silicon nitride crystal particles is 1 to 10 μm.

### Claim 10 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein a porosity of the sintered body is 3% or less (including zero).

### Claim 11 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein when a relative dielectric constant at 50 Hz is expressed as εr50, and a relative dielectric constant at 1 kHz is expressed as εr1000, the sintered body satisfies a relation: (εr50−εr1000)/εr50≤0.1.

### Claim 12 (depends on 1)

A silicon nitride substrate comprising the high thermal conductive silicon nitride sintered body according to claim 1.

### Claim 13 (depends on 12)

The silicon nitride substrate according to claim 12, wherein a thickness of the silicon nitride substrate is 0.10 mm or more and 0.70 mm or less.

### Claim 14 (depends on 13)

The silicon nitride substrate according to claim 13, wherein the thickness of the silicon nitride substrate is 0.10 mm or more and less than 0.30 mm.

### Claim 15 (depends on 12)

The silicon nitride substrate according to claim 12, wherein a maximum diameter of the major axes of the silicon nitride crystal particles in the high thermal conductive silicon nitride sintered body is 20% or less of the thickness of the silicon nitride substrate.

### Claim 16 (depends on 12)

A silicon nitride circuit board, wherein a metal plate is bonded to the silicon nitride substrate according to claim 12.

### Claim 17 (depends on 16)

The silicon nitride circuit board according to claim 16, wherein a plurality of metal plates are bonded to at least one surface of the silicon nitride substrate.

### Claim 18 (depends on 16)

The silicon nitride circuit board according to claim 16, wherein a thickness of at least one metal plate is 0.70 mm or more.

### Claim 19 (depends on 16)

A semiconductor apparatus, wherein a semiconductor chip is mounted on the silicon nitride circuit board according to claim 16.

### Claim 20 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein a dielectric voltage level of the silicon nitride sintered body is 10 kV/mm or more.

### Claim 21 (depends on 1)

The high thermal conductive silicon nitride sintered body according to claim 1, wherein a rear earth element of the rare earth element-hafnium-oxygen does not include an element other than yttrium.

### Claim 22 (depends on 21)

The high thermal conductive silicon nitride sintered body according to claim 21, wherein the rare earth element-hafnium-oxygen compound crystal comprises two or more types selected from a Y1.6Hf0.3O3 crystal, a Y0.5Hf0.5O1.75 crystal, and a Y0.1Hf0.9O1.95 crystal.

### Claim 23 (depends on 22)

The high thermal conductive silicon nitride sintered body according to claim 22, wherein an average particle diameter of major axes of silicon nitride crystal particles is 1 to 10 μm.

### Claim 24 (depends on 23)

The high thermal conductive silicon nitride sintered body according to claim 23, wherein when a relative dielectric constant at 50 Hz is expressed as εr50, and a relative dielectric constant at 1 kHz is expressed as εr1000, the sintered body satisfies a relation: (εr50−εr1000)/εr50≤0.1.