Patent ID: 8471377

Claim:
A semiconductor device comprising: a first substrate having a top surface and a flat bottom surface, and having in the top surface, a compound semiconductor layer in which a semiconductor active element is located, and having, in the bottom surface, a first contact region for electrical connection, the first contact region being electrically connected to the semiconductor active element; and a second substrate of a material other than a compound semiconductor, having a flat top surface, and a second contact region buried in and exposed at the top surface, and a having a passive circuit electrically connected to the second contact region, the second substrate having no semiconductor active elements, the passive circuit being either buried within the second substrate or exposed at a bottom side of the second substrate so that there are no irregularities on the top surface of the second substrate, the flat top surface of the second substrate being directly bonded to the flat bottom surface of the first substrate so that the first contact region is electrically connected to the second contact region.