A Cu/ceramic bonded body according to the present invention is formed by bonding a copper member made of copper or a copper alloy and a ceramic member made of AlN or Al.sub.2O.sub.3 using a bonding material containing Ag and Ti, in which a Ti compound layer made of a Ti nitride or a Ti oxide is formed at a bonding interface between the copper member and the ceramic member, and Ag particles are dispersed in the Ti compound layer.

After a wet blasting treatment for jetting a slurry, which contains spherical alumina as abrasive grains in a liquid, to the surface of a ceramic substrate 10 of aluminum nitride sintered body so that the ceramic substrate 10 has a residual stress of not higher than 50 MPa and so that the surface of the ceramic substrate 10 to be bonded to the metal plate 14 has an arithmetic average roughness Ra of 0.15 to 0.30 m, a ten-point average roughness Rz of 0.7 to 1.1 m and a maximum height Ry of 0.9 to 1.7 m while causing the ceramic substrate to have a flexural strength of not higher than 500 MPa and causing the thickness of a residual stress layer 10a formed along the surface of the ceramic substrate 10 to be 25 m or less, the metal plate 14 of copper or a copper alloy is bonded to the ceramic substrate 10, which is obtained by the wet blasting treatment, via a brazing filler metal 12 to produce a metal/ceramic bonding substrate which has an excellent bonding strength of the ceramic substrate 10 to the metal plate 14 and which has an excellent heat cycle resistance.

An assembly comprising: two ceramic bodies, which are joined by means of a joint of an active hard solder, or braze, wherein the active hard solder, or braze, has a continuous core volume, which is spaced, in each case, from the ceramic bodies by at least 1 m, and an average composition C.sub.K with a liquidus temperature T.sub.l(C.sub.K), wherein the composition C.sub.K has a coefficient of thermal expansion (C.sub.K), wherein (C.sub.K)=m.Math.(K), wherein m1.5, especially m1.3 and preferably m1.2, wherein (K) is the average coefficient of thermal expansion of the ceramic material of the ceramic bodies, wherein the joint has boundary layers, which border on the ceramic body, wherein at least one of the boundary layers, which lies outside of the core volume, has an average composition C.sub.B with a liquidus temperature T.sub.l(C.sub.B), which lies not less than 50 K, preferably not less than 100 K, and especially preferably not less than 200 K, under the liquidus temperature T.sub.l(C.sub.K) of the average composition C.sub.K of the core volume.

The present invention provides a silicon nitride circuit board in which metal plates are attached on front and rear sides of a silicon nitride substrate having a three-point bending strength of 500 MPa or higher, with attachment layers interposed therebetween, wherein assuming that a thickness of the metal plate on the front side is denoted by t1, and a thickness of the metal plate on the rear side is denoted by t2, at least one of the thicknesses t1 and t2 is 0.6 mm or larger, a numerical relation: 0.10|t1t2|0.30 mm is satisfied, and warp amounts of the silicon nitride substrate in a long-side direction and a short-side direction both fall within a range from 0.01 to 1.0 mm. Due to above configuration, TCT properties of the silicon nitride circuit board can be improved even if the thicknesses of the front and rear metal plates are large.

A pressure sensor, including a platform of ceramic, a measuring membrane arranged on the platform, a pressure measuring chamber enclosed in the platform under the measuring membrane, and at least one metal body connected with the platform via a pressure-tight, preferably elastomer free, mechanical connection. Thermomechanical stresses arising from the connection are reduced by features including that the pressure-tight, mechanical connection occurs via an adapting body arranged between the platform and the metal body. The adapting body has a thermal expansion coefficient, which rises in direction (z) extending from the platform to the metal body from a coefficient of expansion corresponding to a thermal coefficient of expansion of the ceramic of the platform to a coefficient of expansion corresponding to the thermal coefficient of expansion of the metal body, and the adapting body is connected by a first joint with the platform and by a second joint with the metal body.

A bonded substrate includes: a silicon nitride ceramic substrate; a copper plate; and a bonding layer bonding the copper plate to the silicon nitride ceramic substrate, wherein the bonding layer has a first interface in contact with the silicon nitride ceramic substrate and a second interface in contact with the copper plate, and contains a nitride and a silicide of an active metal as at least one metal selected from the group consisting of titanium and zirconium, an atomic fraction of nitrogen of the bonding layer is greatest at the first interface and is smallest at the second interface, and a sum of atomic fractions of the active metal and silicon of the bonding layer is smallest at the first interface and is greatest at the second interface.

A method for the joining of ceramic pieces with a hermetically sealed joint comprising brazing a layer of joining material between the two pieces. The wetting and flow of the joining material is controlled by the selection of the joining material, the joining temperature, the joining atmosphere, and other factors. The ceramic pieces may be aluminum nitride and the pieces may be brazed with an aluminum alloy under controlled atmosphere. The joint material is adapted to later withstand both the environments within a process chamber during substrate processing, and the oxygenated atmosphere which may be seen within the shaft of a heater or electrostatic chuck.

A method for the joining of ceramic pieces with a hermetically sealed joint comprising brazing a layer of joining material between the two pieces. The wetting and flow of the joining material is controlled by the selection of the joining material, the joining temperature, the joining atmosphere, and other factors. The ceramic pieces may be on a non-diffusable type, such as aluminum nitride, alumina, beryllium oxide, and zirconia, and the pieces may be brazed with an aluminum alloy under controlled atmosphere. The joint material is adapted to later withstand both the environments within a process chamber during substrate processing, and the oxygenated atmosphere which may be seen within the shaft of a heater or electrostatic chuck.

There is provided a bonded body of the invention in which a ceramic member formed of a ceramic containing Al and a Cu member formed of Cu or a Cu alloy are bonded to each other, in which a bonding portion is formed between the ceramic member and the Cu member, an active metal compound region formed of a compound containing active metal is formed on the bonded portion on the ceramic member side, and an Al concentration of the bonding portion having a thickness range of 0.5 m to 3 m from one surface of the active metal compound region on the Cu member side towards the Cu member side is in a range of 0.5 at % to 15 at %.

A solder material (30) for bonding a metal layer (20) to a ceramic layer (10), in particular for forming a metal-ceramic substrate as a carrier for electrical components, comprising: a base material and an active metal, wherein the solder material (30) is a foil comprising the base material in a first layer (31) and the active metal in a second layer (32), and wherein the foil has a total thickness (GD) which is less than 50 m, preferably less than 25 m and particularly preferably less than 15 m.