A high-speed bipolar LSI process using self-aligned double diffusion polysilicon technology

A Self-aligned Double Diffusion Polysilicon technology (SDD), assisted by the method of fabricating self-aligned polysilicon base electrodes, has been investigated for the application to high-speed bipolar LSIs and VLSIs. Very shallow emitter-base junctions -- 50nm-deep emitter and 100nm-wide base -- have been realized. A combination of SDD with the self-aligned polysilicon base method enabled to establish a process of fabricating 0.4µm-wide emitters for NPN transistors. The process also realized the active regions of transistors free from damages and the steady reproducibitily of emitter-base double diffusion as well. Cut-off frequency of the transistor was 14GHz under the conditions of 600µA collector current and 3V collector-emitter voltage. Minimum propagation delay time of 72ps was measured by the 51-stage LCML ring-oscillator.