We have successfully achieved a fabrication of BiCMOS with submicron epitaxy using our new designed Si₂H₆ low-pressure, low-temperature reactor for the first time. As we reported before, growth at 800°C produces a defect-free epitaxial layer with a low concentration of impurities on 200 mm diameter wafers. Using this new reactor with Si₂H₆ process, we fabricated successfully ESBIC (Emitter-base self-aligned BiCMOS) with submicron epi-layer. The experimental CMOS and BiCMOS 25-stage ring-oscillators were used to evaluate switching characteristics. As decrease in the epitaxial thickness in CMOS, tpd is increased and the load capacitance dependency unchanged. But, in BiCMOS, as decrease in the epitaxial thickness, the load capacitance is less effective to tpd and tpd decrease in higher load capacitance region corresponding to actual device.