A 26 ps self-aligned epitaxial silicon base bipolar technology

Abstract

A self-aligned epitaxial base technology is presented which allows fabrication of advanced bipolar devices with 40 to 60 nm basewidths and implementation of novel profile design concepts. The viability of this technology for advanced bipolar circuits has been examined by fabricating ECL ring oscillators, thus demonstrating that fully scaled epi-base devices can be successfully integrated. Devices with current gains of 80-90 and intrinsic base sheet resistances less than 10 kΩ/sq were fabricated. Epitaxial technology was used to position a novel lightly doped collector (LDC) spacer within the base collector junction of these heavily doped, thin-base devices to control avalanche breakdown and increase BVCEO. Conventional and active pull-down ECL ring oscillators with minimum gate delays of 40.5 and 26.3 ps, respectively, were fabricated with devices showing a measured cutoff frequency of 19.6 GHz. © 1990 IEEE.