Structure and a method are provided for making a bipolar transistor, the bipolar transistor including a collector, an intrinsic base overlying the collector, an emitter overlying the intrinsic base, and an extrinsic base spaced from the emitter by a gap, the gap including at least one of an air gap and...http://www.google.com/patents/US6940149?utm_source=gb-gplus-sharePatent US6940149 - Structure and method of forming a bipolar transistor having a void between emitter and extrinsic base
