Fabrication of semiconductor integrated circuit structure including injection logic configuration compatible with complementary bipolar transistors utilizing simultaneous formation of device regions

The method of fabricating an integrated circuit in a monolithic semiconductor body, said circuit including a logic gate of the injection logic type in a first portion of said body and complementary bipolar transistors of the NPN and PNP type in second and third portions of said body respectively, said monolithic body comprising a monocrystalline silicon substrate and no more than one epitaxially deposited layer of silicon over said substrate, said complementary transistors being fabricated by the following steps:

• (1) introducing a first N-type dopant into a first limited surface area of the third portion substrate to form the PNP collector isolation zone,
• (2) introducing a second N-type dopant into a limited surface area of the second portion substrate to form the NPN buried collector zone,
• (3) introducing a P-type dopant into a part of said first limited surface area of step (1), and completely within said first limited surface area of the third portion substrate to form the PNP buried collector zone,
• (4) forming on the second and third portion substrate an epitaxial layer of N-type silicon,
• (5) selectively introducing an N-type dopant into surface areas of the epitaxial layer on said second and third portions to form deep collector connection zones, and an annular isolation zone, respectively,
• (6) selectively introducing a P-type dopant into the surface area of said epitaxial layer of said third portion, coincident with said part of Step (3) to reconvert the epitaxial layer portion of the PNP adjoining the buried collector from N-type to P-type,
• (7) selectively introducing an N-type dopant into a surface area of the epitaxial layer on said third portion to form the base zone of said PNP transistor,
• (8) selectively introducing a P-type dopant into a surface area of the epitaxial layer on said second portion to form the base zone of said NPN transistor,
• (9) selectively introducing a P-type dopant into a portion of the base zone of said PNP transistor to form an emitter zone,
• (10) selectively introducing an N-type dopant into a portion of the base zone of the NPN transistor to form an emitter zone,
• the method characterized in that the logic gate is formed in the first portion simultaneously by the following sequence of steps performed simultaneously with specific steps performed on the second and third portions,
• (a) introducing an N-type dopant in accordance with Step (2) for forming an N-type buried layer in said first portion,
• (b) selectively introducing a P-type dopant in accordance with Step (3) for forming a P-type buried layer within said N-type buried layer formed in step (a),
• (c) forming on said first portion in accordance with Step (4) an N-type epitaxial layer,
• (d) selectively introducing an N-type dopant into surface areas of the epitaxial layer on said first portion in accordance with Step (5),
• (e) selectively introducing a P-type dopant into an annular surface area of the epitaxial layer on said first portion in accordance with Step (6) to isolate a portion of said epitaxial layer above the P-type buried layer formed in step (b), and
• (f) then, in a step not necessarily performed simultaneously with specific steps performed on the second and third portions of the chip, forming a rectifying connection to a limited region of the N-type epitaxial layer on said first portion, said region being spaced away from the P-type doped areas formed in Step (e).