Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1983-06-13
1985-07-02
Hearn, Brian E.
Metal working
Method of mechanical manufacture
Assembling or joining
29581, 29582, 29571, 148 332, 148187, 357 55, H01L 21461, H01L 2180
Patent
active
045259240
DESCRIPTION:
BRIEF SUMMARY
Background of the Invention
The invention relates to a method for producing a semiconductor arrangement comprising two antiparallel connected diodes.
Antiparallel connections of diodes are used in control and regulating circuits, for example in d.c. converters. They may comprise two discrete individual elements and may be combined and interconnected on a substrate into a structural unit.
However, modern semiconductor technology also makes it possible to arrange spatially separated layer sequences as diode structures which are integrated in a semiconductor body and which are interconnected in an antiparallel arrangement with the aid of conductor paths.
The drawbacks of the combination of discrete components are the separate costs for the manufacture of the individual elements and for their assembly and interconnection as well as the often undesirable large space requirement and the resulting limitations with respect to use. The drawbacks of the integrated arrangement are, in view of the low electrical demands that can be placed on such circuits, the high costs for the special diffusion and masking steps.
It is the object of the invention to find an anti-parallel connection of diodes which includes the most favorable combination of individual elements with respect to their configuration and manufacture.
Summary of the Invention
The solution of this problem resides in a semiconductor arrangement of the above-mentioned type which includes a semiconductor body having a base region in the form of a zone of the one conductivity type and a further, smaller-area zone adjacent each side of the base region and forming a pn-junction therewith, this further zone being offset with respect to the corresponding zone on the other side of the base region, each such further zone being intended for a diode structure which is spatially and electrically antiparallel to the other such zone. The semiconductor arrangement is also provided with contact metal coatings to electrically connect both diode structures.
A modification is provided in that the free surface section of the base region in each diode structure is provided with a highly doped surface layer of the same conductivity type.
The problem is solved further by a method for producing such a semiconductor arrangement wherein a layer sequence of a center zone and two further zones with pn-junctions therebetween is formed in a semiconductor starting disc of one conductivity type between its major surfaces by diffusing doping material of the other conductivity type from both sides. In this process, the starting disc, after masking, is provided on both sides with a pattern representing a structure of groove-like, mutually parallel recesses which are placed in an offset arrangement with respect to the other side and which interrupt the respectively closest pn-junction. A coating of at least one contact metal is applied to each side of the starting disc and the disc is divided, at least along all of the recesses, into semiconductor components of smaller areal expanse each containing antiparallel diode structures.
The recesses may also be produced by etching or ultrasonic drilling or also by sawing.
The thin, highly doped layer of the same conductivity type provided in the areal sections of the base region which have been exposed by the recesses may be produced by diffusion or by vapor deposition and alloying of doping material.
The contact metal coatings may be produced by electroless deposition of contact metals or by vapor deposition and alloying.
In order to improve the adhesion of the contact metal coatings, the surfaces of the starting disc may be roughened by sand-blasting.
An advantageous modification of the method resides in that contact metals are used which form an ohmic contact with the semiconductor material of the starting disc and that the thin, highly doped layer and the contact metal coatings are produced in one process step.
The advantage of the invention resides in that a compact arrangement of an antiparallel connection of two diodes can be realized with
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Auyang H. L.
Hearn Brian E.
Semikron Gesellschaft fur Gleichrichterbau und Elektronik
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