Abstract Integrated circuit structures are provided wherein three of the regions of a four layer device, such as a controlled rectifier, are the same, in conductivity type, resistivity, and impurity concentration gradient, as the emitter, base, and collector regions of a bipolar transistor. The fourth region of the four layer device is provided by a region that may also be the same as a transistor base region entirely laterally spaced in the surface of the integrated circuit. Described are both structures with junction isolation and with dielectric isolation as well as methods for forming such structures. Means for avoiding parasitic transistor action in junction isolated structures, where such transistor action would detract from intended circuit operation, are also described.
The subject matter of claim 1 wherein: said fourth region is also a region having the same conductivity type, resistivity and impurity concentration gradient as said transistor base region.
Claim 2
Dependent Claim
48 words
The subject matter of claim 1 wherein: said isolation means is a wall of material of the same conductivity type as said transistor base region extending between said transistor collector region and said third region in said second portion to a substrate also of the same conductivity type.
Claim 3
Dependent Claim
47 words
The subject matter of claim 3 wherein a predetermined spacing is provided betWeen said second and fourth regions to permit transistor action therebetween and the spacing of said fourth region from said isolation wall is substantially greater than said predetermined spacing to effectively avoid transistor action therebetween.
Claim 4
Dependent Claim
34 words
The subject matter of claim 4 wherein: said transistor collector region and said third region also comprise a wall of material extending to the surface of lower resistivity than the portion adjacent said junctions.