Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2002-09-16
2004-07-20
Fahmy, Wael (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S335000, C257S548000
Reexamination Certificate
active
06765262
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a high-voltage semiconductor component having a semiconductor substrate of a first conduction type on which a semiconductor layer is provided as a drift path that takes up the reverse voltage of the semiconductor component. The semiconductor layer is either of the first conduction type or of a second conduction type that is opposite the first conduction type. The semiconductor layer is more weakly doped than the semiconductor substrate. Laterally oriented semiconductor regions of the first and second conduction types are alternately provided in the semiconductor layer. Furthermore, the present invention relates to a high-voltage semiconductor component having a MOS field-effect transistor that is formed in a semiconductor substrate and has a drift path that is connected to its drain electrode.
In a semiconductor component known from U.S. Pat. No. 4,754,310, two trench electrodes are provided at a distance from one another in a surface of a semiconductor element.
These trench electrodes adjoin semiconductor regions of different conduction types. This means that a first trench electrode adjoins a p-type conductive area, while a second trench electrode is provided in an n-type conductive area. Between these two areas of different conduction types, there extend laterally alternating p-type and n-type conductive regions that form electrically parallel current paths that considerably reduce the series resistance in the region of the body of the semiconductor component without adversely affecting its blocking capability.
Even high-voltage transistors that operate according to the compensation principle have laterally extending n-type and p-type conductive layers that are arranged alternately with respect to one another and that are preferably manufactured by epitaxy. The source and drain terminals of these high-voltage transistors are provided on the same surface of a semiconductor element.
However, there are also high-voltage DMOS (Diffused Metal Oxide Semiconductor) transistors that also operate according to the compensation principle, and for this purpose, are implemented in what is referred to as hybrid construction technology in which vertically extending n-type and p-type conductive column-shaped regions are provided in the drift path which take up the reverse voltage. These high-voltage DMOS transistors are distinguished by a considerable reduction in the switch-on resistance, that is to say by an enormous Ron gain. However, the multiple epitaxy that is used in the hybrid construction technology entails relatively high costs.
In order to avoid these costs, consideration has therefore already been given to manufacturing the column-like regions by performing trench etching and subsequent epitaxial filling. However, despite extensive trials it has not been possible to date to find a way of permitting such high-voltage DMOS transistors to be fabricated satisfactorily on a large scale.
In particular, Issued German Patent DE 198 18 298 C1 discloses a super-low-impedance vertical MOSFET in which the source and the gate are provided on one surface of a semiconductor element and the drain is provided on the opposite surface of the semiconductor element. Column-like zones run in the direction from the one surface to the opposite surface. These zones are of a different conduction type and are arranged in a drift zone in the semiconductor element. In addition, the drift zone has a plurality of areas of alternate opposite conduction types which extend perpendicularly with respect to the column-like zones and with which contact is made using the column-like zones that are arranged spaced apart from one another. This MOSFET is manufactured using epitaxy and ion implantation steps.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a high-voltage semiconductor component which overcomes the above-mentioned disadvantages of the prior art apparatus of this general type.
In particular, it is an object of the invention to provide a high-voltage semiconductor component that is capable of operating according to the compensation principle and that can be manufactured relatively easily so that it has low manufacturing costs.
With the foregoing and other objects in view there is provided, in accordance with the invention, a high-voltage semiconductor component including: a semiconductor substrate of a first conduction type; a first electrode configured on the semiconductor substrate; a second electrode; and a plurality of alternately configured semiconductor regions including laterally oriented semiconductor regions of the first conduction type and laterally oriented semiconductor regions of a second conduction type opposite the first conduction type. The semiconductor regions of the first conduction type are connected to the semiconductor substrate, and the semiconductor regions of the second conduction type are connected to the second electrode. The high-voltage semiconductor component also includes a semiconductor layer of the second conduction type provided as a region for taking up a reverse voltage. The semiconductor layer is more weakly doped than the semiconductor substrate. The semiconductor layer is located between the semiconductor substrate and the plurality of the alternately configured semiconductor regions. The high-voltage semiconductor component also includes an electrically conductive connection routed through the semiconductor layer. The electrically conductive connection electrically connects the semiconductor regions of the first conduction type to the semiconductor substrate. The high-voltage semiconductor component also includes a further conductive connection routed through the plurality of the alternately configured semiconductor regions. The further conductive connection electrically connects the semiconductor regions of the second conduction type to the second electrode. The second electrode is provided on the semiconductor layer.
In other words, the semiconductor regions of the first conduction type are connected, by an electrical conductive connection routed through the semiconductor layer, to the semiconductor substrate on which a first electrode arranged. The semiconductor regions of the second conduction type are connected, by a further conductive connection routed through the semiconductor regions, to a second electrode provided on the semiconductor layer.
The high-voltage semiconductor component is thus per se a vertical component as the two electrodes are provided on opposite faces of the semiconductor chip. However, it combines, in a surprisingly simple way, the advantages of lateral arrangements and vertical arrangements. The source and the drain terminal of a high-voltage transistor which extends vertically and which operates according to the compensation principle are provided with a laterally extending drift path. This source terminal or drain terminal is connected to the semiconductor substrate in such a way that a structure is produced with a common source or with a common drain.
The manufacturing costs for the high-voltage semiconductor component are considerably reduced as the n-type and p-type (p-type and n-type) conductive layers which form the semiconductor regions of the first and second conduction types can be manufactured in one epitaxy step and the conductive connections can readily be formed, for example, from trenches which are filled with n-type doped or p-type doped polycrystalline silicon. Of course, other suitable materials can also be selected for these conductive connections. Here, only small requirements with respect to the shape of these trenches and their surface condition have to be fulfilled. All that it is necessary to ensure is that there is a pn-type junction between the trenches and the monocrystalline semiconductor material, which is preferably silicon, and this is something that can be achieved by outdiffusion.
The distance between the semiconductor regions of the first and second conduction types, that is to say, the di
Ahlers Dirk
Werner Wolfgang
Fahmy Wael
Greenberg Laurence A.
Infineon - Technologies AG
Locher Ralph E.
Pizarro-Crespo Marcos D.
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