Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Junction field effect transistor
Reexamination Certificate
1998-04-06
2002-06-25
Williams, Alexander O. (Department: 2820)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Junction field effect transistor
C257S655000, C257S133000, C257S605000, C257S606000, C257S483000, C257S484000, C257S492000, C257S493000, C257S495000, C257S170000, C257S173000, C257S134000, C257S138000, C257S347000, C257S105000
Reexamination Certificate
active
06410950
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a power diode including a semiconductor body having an inner zone of a first conduction type, a cathode zone of the first conduction type adjoining the inner zone and having a higher dopant concentration than in the inner zone, and an anode zone of a second conduction type adjoining the inner zone and having a higher dopant concentration than in the inner zone. The invention also relates to a method of producing the power diode as well as to a hybrid diode, a voltage limiter and a freewheeling diode having the power diode.
Such power diodes, also known as pin diodes, have long been known and have been described at length, for instance, by F. Kaussen and H. Schlangenotto in a paper entitled “Aktuelle Entwicklungen bei schnellschaltenden Leistungsdioden” [Current Developments in Fast-Switching Power Diodes], 39. ETG-Fachbericht, VDE Verlag, pp. 25-40, Bad Nauheim, 1992.
An FCI (Field-Controlled-Injection) diode of the type referred to at the outset is known, for instance, as a Read-diode and is described by K. T. Kaschani and R. Sittig in a paper entitled “How to Avoid TRAPATT Oscillations at the Reverse Recovery of Power Diodes”, CAS '95, pp. 571-574, Sinaia, 1995. The subject matter of that publication is hereby expressly incorporated by reference into the present application.
The Read-diode was originally developed as a high-frequency component for generating IMPATT oscillations. The FCI concept is explained below in conjunction with
FIG. 1
, in terms of the known Read-diode in its special embodiment as a pin power diode. The coupling of the electrical fields of the high field zone and the low field zone, in such a pin power diode is effected through the space charge of the coupling zone. However, the space charge coupling has proved to be difficult to handle for the turnoff of power diodes, since as a rule the space charge coupling is very strongly temperature-dependent. It is accordingly difficult to use such pin power diodes in practice.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a power diode, a method of producing the power diode and a hybrid diode, a voltage limiter and a freewheeling diode having the power diode, which overcome the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provide novel FCI diodes in which a high field zone is coupled to a low field zone virtually independently of temperature.
With the foregoing and other objects in view there is provided, in accordance with the invention, a power diode, comprising a semiconductor body having an inner zone of a first conduction type; a cathode zone of the first conduction type, the cathode zone adjoining the inner zone and having a higher dopant concentration than in the inner zone; an anode zone of a second conduction type, the anode zone adjoining the inner zone and having a higher dopant concentration than in the inner zone; and the inner zone and the anode zone define an at least partly curved boundary surface therebetween and/or at least one floating region of the first conduction type is disposed in the inner zone.
In the first embodiment of the invention, the boundary surface between the inner zone and anode zone is curved. Due to this provision, a sharply localized disproportionate field increase is brought about, that is appropriate for the provision of a high field zone and a low field zone, which in that case are not space charge coupled and thus are not sharply temperature-dependent.
In the second embodiment of the invention, at least one region that floats with regard to the potentials and is of the same conduction type as in the inner zone, is located in the inner zone. Due to the introduction of such floating regions, which are typically doped very much more strongly than the inner zone itself, equipotential zones in the inner zone are provided, which cause a disruption of the electrical field and thus effect a sharply localized disproportionate field increase in certain areas. This sharply localized disproportionate field increase in turn brings about the creation of a local high field zone and a low field zone, which in that case are again not space charge coupled and thus are again not subject to severe temperature dependency.
Such power diodes will be referred to below as FCI diodes with geometric coupling.
Pin power diodes with geometric coupling have the advantage, over pin power diodes with space charge coupling, that the turnoff operation proceeds largely independently of temperature.
In addition, geometrically coupled FCI diodes in contrast to the conventional pin diodes have an active, controlled overvoltage limitation, which is largely independent of the storage charge, turnoff speed, and rated service life, which leads to no significant influence on the conducting-state, off-state and turn-on performance, and which furthermore also allows a pronounced reduction in switching losses.
In accordance with another feature of the invention, the at least one floating region has a higher dopant concentration than the inner zone.
In accordance with a further feature of the invention, the inner zone has an anode-side area, and the at least one floating region is disposed in the anode-side area.
In accordance with an added feature of the invention, the floating regions at least partly border on the anode zone.
This assures that the voltage breakdown will occur directly at the pn junction between the anode zone and the floating region.
In accordance with a further feature of the invention, the boundary surface between the inner zone and the floating region is likewise curved. Once again, this causes a disruption of the electrical field and thus a sharply localized disproportionate field increase in these areas. Thus the high field and low field are locally separated by these provisions as well.
In accordance with an added feature of the invention, since the floating regions act like a short circuit in terms of their conduction property, they can also be constructed of conductive material.
In accordance with an additional feature of the invention, very highly doped silicon is used as the conductive material, because of its good conductivity and its simple handling in terms of process technology. However, other conductive materials are also conceivable, such as metals or metal silicides.
In accordance with yet another feature of the invention, there is provided a further zone for producing a second pn junction which may be provided on the anode side or the cathode side. Typically, this zone has a higher dopant concentration than the adjoining anode zone or cathode zone. In this way, a series circuit of a geometrically coupled FCI diode and a further diode connected to it in the off-state direction can be produced. Through the use of this monolithically integrated, anti-parallel diode series circuit, the conducting-state mode of the FCI diode can be suppressed, so that it then functions only as a pure voltage limiter.
Due to the parallel connection of a further diode, an FCI hybrid diode array can be made therefrom, and in it in the conducting-state mode, only the further diode is relevant, while in the off-state mode only the FCI diode is relevant. If the further diode is a component with optimized conducting-state performance, then in this way it is possible simultaneously both to minimize the conducting-state and switching losses and to optimize the turnoff course.
With the objects of the invention in view, there is also provided a method for producing a power diode, which comprises producing an inner zone of a first conduction type in a semiconductor body having an anode side and a cathode side; producing a cathode zone of the first conduction type in the semiconductor body, the cathode zone adjoining the inner zone and having a higher dopant concentration than in the inner zone; producing an anode zone of a second conduction type in the semiconductor body, the anode zone adjoining the inner zone and havi
Sittig Roland
Taghizadeh-Kaschani Karim-Thomas
Greenberg Laurence A.
Infineon - Technologies AG
Locher Ralph E.
Stemer Werner H.
Williams Alexander O.
LandOfFree
Geometrically coupled field-controlled-injection diode,... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Geometrically coupled field-controlled-injection diode,..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Geometrically coupled field-controlled-injection diode,... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2979908