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Bipolar High Frequency Transistor

IP.com Disclosure Number: IPCOM000085667D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Folberth, OG: AUTHOR

Abstract

Bipolar transistors for high-speed digital circuits are generally manufactured in planar technology. During manufacture, high-parasitic capacities and series resistances essentially determine the switching times that have to be put up with.

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Bipolar High Frequency Transistor

Bipolar transistors for high-speed digital circuits are generally manufactured in planar technology. During manufacture, high-parasitic capacities and series resistances essentially determine the switching times that have to be put up with.

In high-speed circuits, the packing density is less a function of the space requirements of the highly miniaturized transistors than of the heat produced and the dissipation problems connected therewith. Therefore, in planar technology much silicon remains unused, causing the undesirable parasitic effects. A transistor structure in which only the silicon volumes necessary for the actual transistor function are provided is designed as follows.

A small base 1 in the form of a square or circular column is limited on the two front faces by a columnar emitter 2 or a collector 3, or an emitter or a collector in the shape of a pyramid or cone fulcrum. On the side faces of the base contacting is effected either by low-resistance silicon and/or by metal. Emitter 2 and collector 3 are highly doped in relation to the base. The remaining volumes are filled by a dielectric 4, preferably SiO(2). Embedded in this dielectric or on its surfaces the wiring is applied in the usual thin-film technology.

The replacement of the unused silicon volume by the dielectric 4 leads to a structure with essentially lower RC time constants than those known from the usual planar technology.

The following method is used to man...