Circuit substrate including insulating layer of aluminum nitride and

Abstract

Disclosed is a circuit substrate and a semiconductor device to which the circuit substrate is applied. The circuit substrate has an insulating layer and an electrically conductive layer. The insulating layer is composed of a sintered aluminum nitride composition containing: aluminum nitride; a first component given by a compound containing an element which is selected from the group consisting of group IIa elements and group IIIa elements of the periodic table; a second component given by either a simple boron or a boron compound; and a third component give by either a simple manganese or a manganese compound. The electrically conductive layer contains: a conductive component given by a metal or an electrically conductive compound for exhibiting electric conductivity; aluminum nitride; the first component; the second component; and the third component. The semiconductor device has the above circuit substrate, a semiconductor element mounted on the circuit substrate, and a cap being tightly bonded to the circuit substrate with a sealing glass to cover the semiconductor element.