Double epitaxial method for fabricating complementary integrated circuit

Claim 1

A method for making a semiconductor integrated circuit device comprising: a. preparing a semiconductor substrate of a first conductivity type having a major face; b. forming a semiconductive buried region of a second conductivity type opposite to the first conductivity type having a high impurity concentration in said substrate adjacent to the major surface thereof at a predetermined zone; c. epitaxially growing a first semiconductive epitaxial layer of the first conductivity type on the major face of said substrate; d. epitaxially growing a second semiconductive epitaxial layer of the second conductivity type on said first epitaxial layer; e. forming at least one semiconductive separating region of the first conductivity type by diffusing an impurity through said second epitaxial layer to reach said first epitaxial layer so as to divide said second epitaxial layer into at least a first and a second separated regions, wherein the impurity of said buried region is diffused through said first epitaxial layer into said second epitaxial layer so as to form an inversion region of the second conductivity type in said first epitaxial layer, said first separated region being formed so as to overlie said inversion region; f. forming a first surface diffused region of the first conductivity type in said first separated region; g. forming a second surface diffused region of the second conductivity type in said first surface diffused region thereby forming a first transistor structure with said first separated region and said first and second surface diffused regions functioning respectively As the collector, base and emitter; and h. forming a third surface diffused region of the first conductivity type in said second separated region thereby forming a second transistor structure different in type from that of said first transistor structure with said substrate, said second separated region and said third surface diffused region serving respectively as the collector, base and emitter.

Claim 3

A method for forming at least one separated semiconductive single crystal region having a high impurity concentration region at the bottom thereof, comprising: a. preparing a semiconductor substrate of a first conductivity type having a major face; b. forming a semiconductive buried region of a second conductivity type opposite to the first conductivity type containing an impurity of the second conductivity type with a high impurity concentration in said substrate adjoining the major face thereof in a predetermined area; c. growing a first semiconductive single crystal layer of the first conductivity type on the major face of said substrate so as to overlie said buried region; d. growing a second semiconductive single crystal layer of the second conductivity type on said first layer; and e. diffusing an impurity of the first conductivity type into said second layer from the upper face thereof so as to pass therethrough and to reach said first layer by a thermal treatment during which the impurity of the second conductivity type contained in said buried region is concurrently diffused into said layer from the bottom thereof so as to pass therethrough and to reach said second layer, the impurity of the first conductivity type diffused into said second layer forming a separating inversion region of the first conductivity type for separating from said second layer a separated region thereof to which said buried region is integrally connected by an inversion region which is formed with the impurity diffused into said first layer from said buried region.

Claim 4

A method for making a transistor comprising the steps of: a. preparing a semiconductor substrate of a first conductivity type having a major face; b. forming a semiconductive buried region of a second conductivity type opposite to the first conductivity type containing an impurity of the second conductivity type with a high impurity concentration in said substrate adjoining the major face thereof; c. growing a first semiconductive single crystal layer of the first conductivity type having a low impurity concentration on the major face of said substrate so as to overlie said buried region; d. growing a second semiconductive single crystal layer of the second conductivity type on said first layer; e. diffusing an impurity of the first conductivity type into said second layer from the upper face thereof through said first layer so as to form therewith a separating region of the first conductivity type and to reach said first layer by a thermal treatment during which the impurity of the second conductivity type contained in said buried region is concurrently diffused into said first layer from the bottom thereof so as to form an inversion region of the second conductivity type through said first layer and to reach said second layer, said separating region separating from said second layer a separated region thereof and said inversion region integrally connecting said buried region to said separated region; f. forming a first surface region of the first conductivity type in said separated region; and g. forming a second surface region of the second conductivity type in said first surface region to thereby form a transistor structure with said separated region and said first and second suRface regions functioning, respectively, as collector, base and emitter.

Claim 5

A method for making complementary transistors comprising the steps of: a. preparing a semiconductor substrate of a first conductivity type having a major face; b. forming a semiconductive buried region of a second conductivity type opposite to the first conductivity type having a high impurity concentration in said substrate adjoining the major face thereof; c. growing a first semiconductive single crystal layer of the first conductivity type having a low impurity concentration on the major face of said substrate so as to overlie said buried region; d. growing a second semiconductive single crystal layer of the second conductivity type on said first layer; e. forming a semiconductive separating region of the first conductivity type in said second layer by diffusing an impurity into said second layer so as to extend through said second layer from the upper face thereof to said first layer and to thereby divide said second layer into a first separated region overlying said buried region and a second separated region; f. forming a second semiconductive surface region of the first conductivity type in said first separated region; g. forming a secnd semiconductor surface region of the second conductivity type in said first surface region to thereby form a first transistor structure with said first separated region and said first and second surface regions functioning, respectively, as collector, base and emitter; and h. forming a third semiconductor surface region of the first conductivity type in said second separated region to thereby form a second transistor structure different in type from that of said first transistor structure with said substrate as well as said first layer, said second separated region and said third surface region functioning, respectively, as collector, base and emitter; a portion of the impurity of the second conductivity type contained in said buried region being extended through said first layer and reaching said first separated region during the step of forming said separating region to thereby form an inversion region of the second conductivity type through said first layer.