US Patent 7504707 Semiconductor device and manufacturing method thereof

A semiconductor device in which a main current flows in a direction of the thickness of a semiconductor substrate, to attain desirable electric characteristics. P type semiconductor regions and N type semiconductor regions are alternately provided with an interval therebetween, both regions in a surface of a second main surface of a semiconductor substrate. Between the P type semiconductor regions and the N type semiconductor regions, trenches formed in the surface of the semiconductor substrate are filled with insulators, thereby forming trench isolation structures. Moreover, a second main electrode is formed in contact with both the P type semiconductor regions and the N type semiconductor regions.