Abstract: A semiconductor device having a semiconductor element mounted on an insulating substrate and a decoupling capacitor provided on the semiconductor element. The semiconductor device minimizes the occurrence of switching noise. The semiconductor device comprises an insulating substrate, a semiconductor element mounted on said insulating substrate, and a decoupling capacitor which is joined to the upper surface of said semiconductor element and is electrically connected to said semiconductor element, wherein said decoupling capacitor has a coefficient of thermal expansion close to the coefficient of thermal expansion of said semiconductor element, and is electrically connected to said semiconductor element by soldering and is further secured to said semiconductor element.

Abstract: A dielectric ceramic composition having a high dielectric constant and a coefficient of thermal expansion nearly comparable with that of alumina, and a package for packaging semiconductor. The dielectric ceramic composition contains 0.1 to 0.6 parts by weight of manganese reckoned as an oxide per 100 parts by weight of chief components of the formula xTiO.sub.2 .cndot.yMgO.cndot.zSrO or of the formula xTiO.sub.2 .cndot.yMgO.cndot.zCaO wherein x, y and z are numerals that lie within given ranges. The package for packaging semiconductor comprises a package body composed of alumina and having a semiconductor-mounting portion, and a capacitor made up of a dielectric layer and an electrode layer provided on said semiconductor-mounting portion, wherein the dielectric layer is composed of the TiO.sub.2 --MgO--SrO--MnO.sub.2 -type dielectric ceramic or the TiO.sub.2 --MgO--CaO--MnO.sub.2 -type dielectric ceramic.