Semiconductor device and method of manufacturing same

Abstract

The invention relates to an essentially discrete semiconductor device comprising a semiconductor body ( ) having a first, preferably bipolar, transistor (T ) with a first region ( ) forming a collector ( ) of T , and a second, preferably also bipolar, transistor (T ) with a second region ( ) forming a collector ( ) of T , which transistors (T , T ) are in a cascode configuration wherein the collector ( ) of T is connected to the emitter ( ) of T . Such a device cannot suitably be used in a base station for mobile communication. According to the invention, the first region ( ) and the second region ( ) are positioned next to each other within a semiconductor region ( ), a part of which situated below the first region ( ) is provided with a higher doping concentration at the location of T . In this way, T has a low collector-emitter breakdown voltage and a high cutoff frequency, whereas for T said voltage and frequency are, respectively, high(er) and low(er). The resultant device is very suitable, on the one hand, for a high voltage application, for example 28 V, and a high power application, for example 100 W and, on the other hand, the device can still operate at a very high speed and hence is very suitable for the above application. Moreover, the device can be manufactured very easily using a method according to the invention. Preferably, the device is rendered suitable for surface mounting, and the semiconductor body is attached to an isolating substrate ( ), while the parts thereof that are situated outside T and T are removed.