Hetero-guardring fully self-aligned HBT (HG-FST) for microwave and high-speed digital applications

Typical features and suitable application fields for HBTs (Heterojunction Bipolar Transistors) are demonstrated by using an active device application radar chart. To enhance the typical features, AlGaAs/GaAs Hetero-Guardring Fully Self-Aligned HBT (HG-FST) has been newly developed. By introducing the Hetero-Guardring layer, composed of depleted AlGaAs, at emitter periphery, an emitter size effect on current gain has been significantly reduced, and 1/f noise has been improved by 17 dB compared with conventional AlGaAs/GaAs HBT. DC and RF yield could also be improved. As suitable applications of HG-FST, a low phase noise 22 GHz MMIC (Monolithic Microwave IC) oscillator, ultrahigh-speed fiber optical communication ICs such as a transimpedance amplifier, a D-type flip-flop, an LD driver circuit, and a general-purpose 1K gate array LSI exhibiting 82 psec propagation delay time under FI = F0 = 3, l = 1 mm condition have been developed.