Fully self-aligned AlGaAs/GaAs heterojunction bipolar transistors for high-speed integrated-circuits application

Structure optimization, uniformity consideration, and high-speed circuit performance for an AlGaAs/GaAs heterojunction bipolar transistor (HBT) are described. The HBT is fabricated in a fully self-alignment manner using only a single photoresist mask for achieving submicrometer-dimension devices, and, thus reducing parasitic elements. The fabricated HBT´s exhibit excellent threshold voltage deviation σV_BE=2 mV on a 2-in wafer, a CML gate propagation delay time τ_pd=9.5 ps, and a toggle frequency f_tog=13.3 GHz for a CML divide-by-two frequency divider