BiCMOS monolithic IC mfr. - avoids need for epitaxial and buried layers

摘要

Prodn. of a monolithic IC, with one or more pairs of C/MOSFETs and one or more planar non-bipolar transistors, involves (i) forming an n-type moat (2) for the bipolar portion in a p-type substrate (1); (ii) covering the substrate surface with a thick oxide film (3) and, in the active transistor regions, a thin oxide film; (iii) depositing a thin polysilicon layer onto the oxide films, removing the polysilicon layer in the base region using a photolacquer mask and then implanting boron through the exposed thin oxide film; (iv) exposing the emitter region and the regions for the future collector connection regions, applying an n-doped polysilicon layer (10) over the entire surface and then structuring to expose the junctions between the base and collector regions; (v) implanting boron to obtain a low ohmic connection between intrinsic and extrinsic base regions; (vi) producing oxide spacers (18) in conventional manner and producing the base connection regions by boron implantation; and (vii) producing a titanium silicide layer (22) on all the exposed silicon and polysilicon surfaces. ADVANTAGE - The process avoids the need for epitaxial layers and buried layers, is less critical w.r.t. alignment tolerances, is space-saving and does not require additional photo process steps.