Compound semiconductor device

A semiconductor device comprising:

• a heterojunction bipolar transistor including plural unit transistors, each unit transistor including:
• a collector layer, base layer, and emitter layer;
• a base electrode on the base layer;
• and
• an emitter electrode on the emitter layer;
• base wires respectively electrically connecting the base electrodes of the unit transistors to an input terminal;
• a metallization layer electrically connecting the emitter electrode of each of the plural unit transistors to each other, and having first portions respectively over each of the emitter electrodes and second portions respectively overhanging each of the base electrodes;
• a dielectric layer over the metallization layer, the dielectric layer including a conductor filled via opening overlying each of the plural unit transistors;
• and
• a bump elongated in a length direction is positioned above the plural unit transistors and has a width in a width direction transverse to the length direction, and, for each of the plurality of unit transistors, the bump electrically connects the metallization layer with the conductor filled via opening therebetween, wherein
• for each of the plural unit transistors:
• the overlying via opening overlaps in a plan view a width portion of the bump, the overlying via opening covering between −25 percent and 25 percent of the bump when a line drawn in the center of the bump in the width direction is defined as 0 percent, one edge of the bump in the width direction is defined as 50 percent, and another edge of the bump in the width direction is defined as −50 percent, and
• the entirety of the base electrode is positioned in the plan view within a region of the overlying via opening, the region covering from −25 percent to 25 percent of the overlying via opening, when a line drawn in the center of the via opening in the width direction is defined as 0 percent, one edge of the via opening in the width direction is defined as 50 percent, and another edge of the via opening in the width direction is defined as −50 percent.