VERTICAL POWER TRANSISTOR AND FABRICATION METHODS

摘要

A power permeable base transistor comprising: a base layer formed as comb structures with grating teeth (50, 52, 54, 56) of the combs extending into active regions (34, 36, 38, 40) of semiconductor material and extended active regions (34, 36, 38, 40) separated by inactive regions (35, 37, 39, 41, 43) over which collector contacts (24, 26, 28) extend. These features improve heat dissipation in operation. Current density can also be reduced by provision of thick gold collector contacts (24, 26, 28). Large devices have digitated base layers. A processing method of forming a layer of material having a pattern of high resolution portions and lesser resolution portions, comprising the steps of sputtering a uniform layer of tungsten, forming a nickel mask over the tungsten by both X-ray and photolithography techniques, and etching the tungsten exposed by the nickel mask. The resulting patterned layer can be the aforesaid comb structure. A method of forming alloyed contacts with partial ohmic contact to a semiconductor layer having proton bombarded insulating regions formed therein. A heterojuncction bipolar transistor with extended active regions (152, 154) separated by inactive regions (132) over which collector contacts (144, 146) extend is also disclosed.