US 4,190,466 A · Method for making a bipolar transistor structure utilizing self-passivating diffusion sources

Abstract

A semiconductor structure, formed within a recessed oxide isolation region, includes a semiconductor substrate of a first conductivity type within which a collector of opposite conductivity type is formed below the surface of the substrate and extending in part to the surface of the substrate for ease of contact. A first layer of doped polycrystalline silicon or polysilicon is formed on a first portion of the surface of the substrate and in electrical contact with the substrate which acts as the base of a transistor. The first polysilicon layer is oxidized to form an outer insulating layer thereover. A second doped polysilicon layer is disposed over the outer insulating layer onto a second portion of the surface of the substrate so as to be spaced from the first portion by only the thickness of the outer insulating layer on the first polysilicon layer. The dopant in the second polysilicon layer is driven into the surface of the semiconductor substrate to form an emitter therein. Means, which may include a portion of the second polysilicon layer, are provided for electrically contacting the collector to thus form a completed compact bipolar transistor which has very high performance.

Claims28

Dependent claims

A method of making a transistor structure in a semiconductor substrate of a given conductivity type having a major surface comprising the steps of:

isolating a region of said semiconductor substrate at said major surface,
forming a collector region of a conductivity type opposite to that of said given conductivity type below and spaced from said major surface so as to define a base region between said collector region and said major surface,
applying a first self-passivating conductive layer to a first portion of said major surface,
passing impurities of said given conductivity type to said first portion of said major surface through said first self-passivating conductive layer to form a contact region in said base region,
forming an insulating layer on the outer surface of said self-passivating conductive layer,
applying a second conductive layer to said insulating layer and to a second portion of said major surface adjacent to said first surface portion, and
passing impurities of said opposite conductivity type through said second conductive layer to said second surface portion adjacent said first surface portion to form within said base region an emitter region spaced within the thickness of said insulating layer from said first surface portion.

4 more elements

A method of making a transistor structure in a semiconductor substrate of a given conductivity type having a major surface comprising the steps of:

isolating a region of said semiconductor substrate at said major surface,
forming a collector region of a conductivity type opposite to that of said given conductivity type below and spaced from said major surface so as to define a base region between said collector region and said major surface,
applying a first self-passivating conductive layer to a plurality of selected first portions of said major surface,
passing impurities of said given conductivity type to said plurality of selected first portions of said major surface through said first self-passivating conductive layer to form a contact region in said base region,
forming an insulating layer on the outer surface of said self-passivating conductive layer,
applying a like plurality of segments of a second conductive layer to said insulating layer and to a like plurality of selected second portions of said major surface, each of said selected second portions being adjacent to one of said selected first portions of said major surface, and
passing impurities of said opposite conductivity type through said plurality of segments of said second conductive layer to said plurality of selected second portions of said major surface to form within said base region a like plurality of emitters, each being spaced within the thickness of said insulating layer from said first surface portions.

4 more elements

Dependencies are inferred from the claim text.

Method for making a bipolar transistor structure utilizing self-passivating diffusion sources

Life of this patent

Method for making a bipolar transistor structure utilizing self-passivating diffusion sources

Life of this patent

Abstract

Claims28