Method of fabricating an I2 L element and a linear transistor on one chip

Claim 1

A method of manufacturing an integrated circuit comprising at least one I 2 L element and at least one linear transistor, comprising: a first step of forming on a semiconductor substrate of a first conductivity type high impurity concentration layers of a second conductivity type; a second step of growing an epitaxial layer of the second conductivity type on said substrate and said high impurity concentration layers; a third step of separating said epitaxial layer into a plurality of island regions by forming an isolating region of the first conductivity type, a fourth step of forming a high impurity concentration region of the second conductivity type in at least one of said island regions inn which the I 2 L element is formed, said high impurity concentration region reaching said high impurity concentration layers; a fifth step of doping an impurity in said island region to form a deep injector region of the I 2 L element and a deep base region of a vertical transistor, said deep injector and base regions being low impurity concentration layers of the first conductivity type; a sixth step of forming, in the base region, a collector region 18 of the vertical transistor, said region being an impurity layer of the second conductivity type; a seventh step performed after the sixth step of forming a base region of the linear transistor in at least one of the remaining island regions by doping an impurity into said island region shallower than said base region of the vertical transistor, said base region being an impurity layer of the first conductivity type; and an eighth step of forming an emitter region and a collector region of the linear transistor respectively in said base region of the linear transistor and said remaining island region, said collector region of the linear transistor being a high impurity concentration layer of the second conductivity type and said emitter region of the linear transistor being an impurity layer of the second conductivity type which has an impurity concentration higher than that of the collector region of the vertical transistor which is formed in the base region thereof.

Claim 2

A method of manufacturing an integrated circuit comprising at least one I 2 L element and at least one linear transistor, comprising: a first step of forming on a semiconductor substrate of a first conductivity type high impurity concentration layers of a second conductivity type; a second step of growing an epitaxial layer of the second conductivity type on said substrate and said high impurity concentration layers; a third step of separating said epitaxial layer into a plurality of island regions by forming an isolating region of the first conductivity type, a fourth step of forming a high impurity concentration region of the second conductivity type in at least one of said island regions inn which the I 2 L element is formed, said high impurity concentration region reaching said high impurity concentration layers; a fifth step of doping an impurity in said island region to form a deep injector region of the I 2 L element and a deep base region of a vertical transistor, said deep injector and base regions being low impurity concentration layers of the first conductivity type; a sixth step of forming, in the base region, a collector region 18 of the vertical transistor, said region being an impurity layer of the second conductivity type; a seventh step performed after the sixth step of forming a base region of the linear transistor in at least one of the remaining island regions by doping an impurity into said island region shallower than said base region of the vertical transistor, said base region being an impurity layer of the first conductivity type; and an eighth step of forming an emitter region and a collector region of the linear transistor respectively in said base region of the linear transistor and said remaining island region, said collector region of the linear transistor being a high impurity concentration layer of the second conductivity type and said emitter region of the linear transistor being an impurity layer of the second conductivity type which has an impurity concentration higher than that of the collector region of the vertical transistor which is formed in the base region thereof.