A high frequency and high power semiconductor device comprising unit cells of the same shape, connected in parallel and fabricated on a chip. The thermal resistance of the chip is reduced by arranging the unit cells in a zigzag pattern. The zigzag arrangement of the unit cells is such that each unit cell in a line is offset by approximately one-half pitch from the unit cells in neighboring lines. As a result of the zigzag arrangement of the unit cells, the temperature of each unit cell is less influenced by heat from the unit cells in neighboring lines than are unit cells in an orthogonal matrix. In addition, the thermal distribution of the unit cells is improved to prevent hot spots. Using the zigzag arrangement, a single transistor can output over 100 watts C.W. at more than 900 MHz.

A power transistor includes a plurality of emitter regions and a plurality of base contacts. In order to decrease base resistance, each of the plurality of emitter regions is adjacent to at least four base contacts. The entire transistor includes multiple emitter regions, e.g., greater than or equal to about 1,000 with no upper limit wherein the actual number of emitter regions is dependent on the desired current carrying capacity. The emitter regions are directly connected in parallel to the high current carrying metal layer of the transistor through vias or metal contact studs. The size of the emitter regions should be made as small as the process design rules will allow in order to allow an increase in the perimeter to area ratio of the emitter region which, for a given current, decreases the peak current density.

A bipolar transistor is disclosed. The bipolar transistor comprises: a silicon substrate; a collector formed in the semiconductor substrate, a base formed over the collector, the base having an intrinsic base region and an extrinsic base region, the extrinsic base region forming an internal resistor, an emitter formed over the intrinsic base region; and a dielectric layer formed between the extrinsic base region and the collector, the extrinsic base region. the dielectric layer and the collector forming an internal capacitor. The base of the transistor may be silicon-germanium.