U.S. Philips Corporation

Koninklijke Philips Corporation N.V.

Holger Schligtenhorst

Godefridus A M Hurkx

Bernd Sievers

Ronald Dekker

Anco Heringa

Henricus Godefridus Rafael Maas

Andrew M Warwick

A semiconductor device includes a preferably discrete bipolar transistor with a collector region, a base region, and an emitter region which are provided with connection conductors. A known means of preventing a saturation of the transistor is that the latter is provided with a Schottky clamping diode. The latter is formed in that case in that the connection conductor of the base region is also put into contact with the collector region. Here, the second connection conductor is exclusively connected to the base region, and a partial region of that portion of the base region which lies outside the emitter region, as seen in projection, lying below the second connection conductor is given a smaller flux of dopant atoms. The bipolar transistor is provided with a pn clamping diode which is formed between the partial region and the collector region.

Semiconductor device with a bipolar transistor, and method of manufacturing such a device

Method of producing a schottky varicap

In a semiconductor switch device such as an NPN transistor (T) or a power switching diode (D), a multiple-zone first region ( ) of one conductivity type forms a switchable p-n junction ( ) with a second region ( ) of opposite conductivity type. In accordance with the invention, this first region ( ) includes three distinct zones, namely a low-doped zone ( ), a high-doped zone ( ), and an intermediate additional zone ( ). The low-doped zone ( ) is provided by a semiconductor body portion ( ) having a substantially uniform p-type doping concentration (P&minus;) and forms the p-n junction ( ) with the second region ( ). The distinct additional zone ( ) is present between the low-doped zone ( ) and the high-doped zone ( ). The high-doped zone ( ) which may form a contact zone has a doping concentration (P&plus;&plus;) which is higher than that of the low-doped zone ( ) and which decreases towards the low-doped zone ( ). The distinct additional zone ( ) has an additional doping concentration (P&plus;) which is lower than the doping concentration (P&plus;&plus;) of the high-doped zone ( ) and which decreases towards the low-doped zone ( ). This triple-zone formation for the first region ( ) permits an improvement in switching behaviour, e.g. in terms of fall-time and energy dissipation during turn-off of the device (T, D). A very low doping (P&minus;) can be used for low-doped zone ( ) so that, in the off-state of the device (T, D), this zone ( ) and also the additional zone ( ) can be fully depleted. The additional zone ( ) having its additional doping concentration provides a path for extracting residual charge carriers from the low-doped zone ( ) when the device (T, D) is being switched off.

Semiconductor switch devices having a region with three distinct zones and their manufacture

The invention relates to a semiconductor device including a preferably discrete bipolar transistor with a collector region, a base region, and an emitter region which are provided with connection conductors. A known means of preventing a saturation of the transistor is that the latter is provided with a Schottky clamping diode. The latter is formed in that case in that the connection conductor of the base region is also put into contact with the collector region. In a device according to the invention, the second connection conductor is exclusively connected to the base region, and a partial region of that portion of the base region which lies outside the emitter region, as seen in projection, lying below the second connection conductor is given a smaller flux of dopant atoms. The bipolar transistor in a device according to the invention is provided with a pn clamping diode which is formed between the partial region and the collector region. Such a device has excellent properties, such as a short switching time and a saturation collector-emitter voltage which is not too high, while having a low, non-variable and well reproducible leakage current, unlike the known device. The reduced flux of dopant atoms of the partial region is preferably realized in that the partial region is given a smaller doping concentration and/or thickness than the remainder of the portion of the base region which lies outside the emitter region. In a favorable modification, a region provided simultaneously with the emitter region is present between the partial region and the second connection conductor.

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Eindhoven, Netherlands

Holger Schligtenhorst