This A copper/ceramic bonded body includes: a copper member made of copper or a copper alloy; and a ceramic member made of oxygen-containing ceramics, wherein the copper member and the ceramic member are bonded to each other, a magnesium oxide layer is formed on a ceramic member side between the copper member and the ceramic member, and an active metal oxide phase composed of an oxide of one or more active metals selected from Ti, Zr, Nb, and Hf is dispersed inside a copper layer in contact with the magnesium oxide layer.

A semiconductor substrate includes a dielectric insulation layer and a first metallization layer attached to the dielectric insulation layer. The dielectric insulation layer includes a first material having a thermal conductivity of between 25 and 180 W/mK, and an insulation strength of between 15 and 50 kV/mm, and an electrically conducting or semiconducting second material evenly distributed within the first material.

A bonded body according to an embodiment includes a substrate, a metal member, and a bonding layer. The bonding layer is provided between the substrate and the metal member. The bonding layer includes a first particle including carbon, a first region including a metal, and a second region including titanium. The second region is provided between the first particle and the first region. A concentration of titanium in the second region is greater than a concentration of titanium in the first region.

Electrical insulating properties between adjacent copper plates are improved while a defect of a bonded substrate which is caused by concentration of stress to end portions of the copper plates is prevented. A bonded substrate includes a silicon nitride ceramic substrate, a copper plate, and a bonding layer. The copper plate and the bonding layer are disposed on the silicon nitride ceramic substrate. The bonding layer bonds the copper plate to the silicon nitride ceramic substrate. The bonding layer includes: an interplate portion between the silicon nitride ceramic substrate and the copper plate; and a protruding portion protruding from between the silicon nitride ceramic substrate and the copper plate. Exposure of the silicon nitride ceramic substrate is prevented at a position where the protruding portion is disposed.

A power module substrate includes an insulating substrate and a metal plate. The metal plate is joined to the insulating substrate with a brazing material in between. As to surface roughness of a lateral surface of the metal plate in a thickness direction, the surface roughness of at least a corner part farthest from a center of the metal plate in plan view is larger than the surface roughness of plane parts sandwiching the corner part.

Provided are a ceramic substrate and a method of manufacturing the same, which suppress a warpage phenomenon caused by a difference in volumes occupied by upper and lower metal layers of a ceramic base material and controls areas of the upper and lower metal layers especially when thicknesses of the upper and lower metal layers on the ceramic base material are equal to each other, thereby reducing a defect rate of the ceramic substrate.

A wiring substrate includes an insulating substrate, a conductor and an Ni film. The insulating substrate has a first surface and a second surface on a side opposite the first surface, and contains AlN. The conductor is disposed on the first surface and contains Cu. The Ni film is disposed so as to extend across an upper surface and a side surface of the conductor to the first surface. Ti oxide is scattered so as to be at a plurality of points on the first surface.

A silicon nitride substrate includes silicon nitride and magnesium, in which when a surface of the silicon nitride substrate is analyzed with an X-ray fluorescence spectrometer under the specific Condition I, XB/XA is 0.8 or more and 1.0 or less.

Provided is a method for producing a silicon nitride sintered body including: a step of molding and firing a raw material powder containing silicon nitride, in which an α-conversion rate of the silicon nitride contained in the raw material powder is less than or equal to 30 mass %. A thermal conductivity (at 20° C.) of the silicon nitride sintered body exceeds 100 W/m.Math.K and a fracture toughness (K.sub.IC) is greater than or equal to 7.4 MPa.Math.m.sup.1/2.

A gas plug of the present disclosure is composed of a columnar porous composite in which a plurality of silicon compound phases containing silicon carbide as a main component are connected to each other via a silicon phase having silicon as a main component. The porous composite is housed inside a tubular body made from a dense ceramic.