POWER TRANSISTORS FOR RADIO FREQUENCIES

摘要

A field effect transistor is made on a chip (20) comprising a SiC-substrate. The transistor includes a plurality of densely stacked parallel transistor cells occupying totally a rectangular area (21). Each transistor cell has parallel strip-shaped regions forming the electrodes and active areas of the cell and each in-ner cell shares its drain and sources electrodes with neighbour-ing cells. In order to give a good power dissipation allowing an electrical high power of the transistor, the rectangular area has a very elongated shape and specifically it should have a width not larger than substantially 50 mu . In the rectangular area all the transistor cells have their strip-shaped regions located in parallel to short sides of the rectangular area and are generally very short considering the length of the rectangular area. Thus specifically also each cell has a length not larger than sub-stan-tially 50 mu . The distances from the long sides of the rect-angu-lar area to the edges of the chip should be at least 50 % and preferably 60 % of the thickness of the chip to allow a good thermal flow out of the active rectangular area. A plurality of such very elongated active areas can be located on a single chip.