A novel high-speed self-aligned npn bipolar transistor fabrication process is presented. Base contacts are formed by epitaxial lateral overgrowth of single-crystal silicon on silicon-dioxide. Impurity-enhanced oxidation of silicon is used to achieve self-alignment of the emitter. Ultra-low resistance p-type base contacts have been fabricated with measured sheet resistances of 19Ω/⌕. © 1990, The Institution of Electrical Engineers. All rights reserved.