Heterojunction bipolar transistors having bases with different elevations

A structure comprising:

• a first heterojunction bipolar transistor including a first subcollector, a first collector over the first subcollector, a first base over the first collector, and a first emitter over the first base, the first collector having a first thickness, and the first heterojunction bipolar transistor formed in a first device region of a substrate;
• a second heterojunction bipolar transistor including a second subcollector, a second collector over the second subcollector, a second base over the second collector, and a second emitter over the second base, the second heterojunction bipolar transistor formed in a second device region of the substrate, the second collector having a second thickness that is greater than the first thickness of the first collector;
• and
• a shallow trench isolation region laterally arranged at a transition between the first device region of the substrate and the second device region of the substrate, the shallow trench isolation region having a top surface that is inclined with a slope from the second device region of the substrate to the first device region of the substrate.