A semiconductor device is disclosed that includes an interposer and a semiconductor chip. The interposer includes a Si substrate; multiple through vias provided through an insulating material in corresponding through holes passing through the Si substrate; a thin film capacitor provided on a first main surface of the Si substrate so as to be electrically connected to the through vias; and multiple external connection terminals provided on a second main surface of the Si substrate so as to be electrically connected to the through vias. The second main surface faces away from the first main surface. The semiconductor chip is provided on one of the first main surface and the second main surface so as to be electrically connected to the through vias. The Si substrate has a thickness less than the diameter of the through holes.