Fabrication and characterization of InP heterojunction bipolar transistorswith emitter edges parallel to [001] and [010] crystal orientations

We present a study of fully-self aligned InP-based heterojunction bipolar t ransistors (HBTs) with the emitter edges oriented parallel to the [0,0,1] a nd [0,1,0] crystal orientations. A technology based on vertical and lateral wet etching of InP was developed to fabricate emitter-up and collector-up InP/InGaAs HBTs with reduced parasitic resistances and capacitances. For em itter-up HBTs, the undercut distance between the base contact and the emitt er active area was <0.3 mu m in all directions, and high frequency performa nce of f(T) = 105 GHz and f(MAX) = 82 GHz were obtained for a 4 x 12 mu m(2 ) emitter area. For collector-up metal HBTs (MHBTs), emitter widths as smal l as 0.5 mu m were formed by lateral wet etching with a relative area fluct uation less than 10%, and high frequency performance of f(T) = 40GHz, and f (MAX) = 160 GHz, were obtained for a 0.5 x 52 mu m(2) emitter area.