A microwave PNP bipolar silicon power transistor

In the last few years, several microwave NPN silicon power transistors (1-5) have been reported. This paper presents PNP microwave power transistor. The advantage of this kind of device is seen in high speed switching application with complementary transistors. This type of device allows the total number of devices to be reduced and the performance to be improved in the system or subsystem. The collector-base breakdown voltage (BVCBO) of the order of 90-100 V and the maximum collector current (Icmax) up to 250 mA have been measured. The current gain bandwidth product (ft) in the range of 1.5 GHz to 2 GHz has been obtained. The collector-base capacitance (CCB) at bias voltage of 10 V is about 5 pf with the rise time of the order of a few nanoseconds in the switching application. The collector region of the device is formed by an epitaxially grown p-type layer on a P⁺doped substrate. An ion implantation technique is used to fabricate guard ring, active base and base contact regions. An emitter diffusion is accomplished by the conventional technique. A gold metal scheme with dielectric passivation is used to provide excellent reliability to the device.