CN-121990833-A - Silicon nitride substrate

CN121990833ACN 121990833 ACN121990833 ACN 121990833ACN-121990833-A

Abstract

The present invention provides a silicon nitride substrate having isotropy and high fracture toughness. The solution is a silicon nitride substrate having silicon nitride particles, wherein an average angle between a main surface of the silicon nitride substrate and a long axis of the silicon nitride particles is 35 DEG to 55 DEG, an average aspect ratio of the silicon nitride particles is less than 2, and an average equivalent circle diameter of the silicon nitride particles is more than 3 mu m.

Inventors

ISHIMOTO RYUJI
Motoyama ANRI

Assignees

株式会社德山

Dates

Publication Date: 20260508
Application Date: 20251022
Priority Date: 20241108

Claims (3)

1. A silicon nitride substrate is provided with silicon nitride particles, wherein the average angle between the main surface of the silicon nitride substrate and the long axis of the silicon nitride particles is 35-55 DEG, the average aspect ratio of the silicon nitride particles is less than 2, and the average equivalent circle diameter of the silicon nitride particles is more than 3 mu m.
2. The silicon nitride substrate according to claim 1, wherein the silicon nitride substrate has a fracture toughness of 8 MPa-m 1/2 or more.
3. The silicon nitride substrate according to claim 1 or 2, wherein the silicon nitride substrate has a thermal conductivity of 80W/(m-K) or more.

Description

Silicon nitride substrate Technical Field The present invention relates to a novel silicon nitride substrate. Background Silicon nitride is excellent in mechanical strength, thermal conductivity, and electrical insulation properties, and is used for substrates for semiconductor modules, etc. Conventional silicon nitride substrates generally have a problem of isotropy in which the fracture toughness in the plane direction of the substrate is lower than the fracture toughness in the vertical direction. In order to solve this problem, for example, patent document 1 discloses a silicon nitride sintered body substrate in which columnar grains of silicon nitride are arranged vertically and horizontally in a random or uniform manner as a whole to improve isotropy. Specifically, a silicon nitride substrate having a fracture toughness (fracture toughness) of 6 to 7 MPa·m 1/2 in both the 1 st direction parallel to the substrate plane and the 2 nd direction perpendicular to the substrate plane is obtained. Prior art literature Patent literature Patent document 1 Japanese patent laid-open publication No. 2019-052072 Disclosure of Invention Problems to be solved by the invention As described above, in patent document 1, a silicon nitride substrate having an improved isotropy and a fracture toughness of about 6 to 7 mpa·m 1/2 is obtained, but further improvement in fracture toughness is desired. Accordingly, an object of the present invention is to provide a silicon nitride substrate having isotropy and higher fracture toughness. Means for solving the problems The present inventors have conducted intensive studies to solve the above problems. As a result, it was found that the above-mentioned problems can be solved by controlling silicon nitride particles having a low aspect ratio and a large size to be isotropically oriented, and the present invention has been completed. That is, the present invention is a silicon nitride substrate having silicon nitride particles, wherein an average angle between a main surface (main surface) of the silicon nitride substrate and a long axis of the silicon nitride particles is 35 ° to 55 °, an average aspect ratio of the silicon nitride particles is less than 2, and an average equivalent circle diameter of the silicon nitride particles is more than 3 μm. The fracture toughness of the silicon nitride substrate is preferably 8MPa ·m 1/2 or more, and the thermal conductivity of the silicon nitride substrate is preferably 80W/(m·k) or more. Effects of the invention According to the present invention, a silicon nitride substrate having isotropy and high fracture toughness can be obtained. Detailed Description The silicon nitride substrate of the present invention comprises silicon nitride particles, wherein the average angle between the main surface of the silicon nitride substrate and the long axis of the silicon nitride particles is 35 DEG to 55 DEG, the average aspect ratio of the silicon nitride particles is less than 2, and the average equivalent circle diameter of the silicon nitride particles is more than 3 mu m. The average angle (hereinafter, may be simply referred to as "average angle") between the main surface of the silicon nitride substrate and the long axis of the silicon nitride particles is 35 ° to 55 °, which means that the orientation of the long axis of the silicon nitride particles is random and does not become oriented. Since the characteristics of the silicon nitride substrate largely depend on the properties of the silicon nitride particles as their main components, by having the characteristics, the silicon nitride substrate can exhibit isotropic properties. The average angle is preferably 37 ° to 53 °, more preferably 40 ° to 50 °. The measurement of the above average angle can be performed using an SEM image obtained by observing a cross section obtained by cutting the silicon nitride substrate along the thickness direction of the substrate by a Scanning Electron Microscope (SEM). Specifically, first, 1000 silicon nitride particles were randomly selected in the SEM image. In the case where 1000 silicon nitride particles are not selected in one image, a plurality of images obtained from the same substrate may be used. Next, in each selected silicon nitride particle, the longest straight line among straight lines connecting the particles from edge to edge is taken as a major axis, and an angle between the major axis and the main surface of the substrate is measured. The angle between the long axis and the main surface of the substrate is the smallest value, and any one of 0 DEG to 90 DEG is used. After measuring angles between the long axis and the main surface of the substrate for all the silicon nitride particles, an average angle between the long axis and the silicon nitride particles can be obtained by calculating a weighted average of areas of the particles in consideration of SEM images. The above average angle is obtained by taking into account a weighted avera