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Lateral PNP Transistor With Improved Emitter Field Plate

IP.com Disclosure Number: IPCOM000086911D
Original Publication Date: 1976-Nov-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Ayers, RL: AUTHOR [+3]

Abstract

An improved emitter field plate reduces hot electron induced collector-to-emitter leakage degradation in a lateral PNP transistor. Reduction of the oxide thickness over the N type base region enhances the effect of the field plate over the base.

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Lateral PNP Transistor With Improved Emitter Field Plate

An improved emitter field plate reduces hot electron induced collector-to- emitter leakage degradation in a lateral PNP transistor. Reduction of the oxide thickness over the N type base region enhances the effect of the field plate over the base.

The figure shows an emitter field plate 10 that contacts emitter region 12 and overlies the base region 14 of a lateral PNP transistor including collector 16. A base contact 18 and collector contact 20 are made through openings in an oxide layer 22 formed on an N type epitaxial (epi) layer 24. P+ type isolation regions 28 and an N+ subcollector 30 in a P- type substrate 26 complete the lateral transistor.

The contact 10 to the emitter as well as the contact 20 to the collector are made by etching through the oxide 22 grown after diffusion of the P type regions 12 and 16. The oxide over the P type diffusions 12 and 16 is approximately 4700 Angstroms thick. The field oxide over the base region 14 is approximately 9400 Angstroms thick. The emitter contact hole etch pattern is extended over the active base region. Because of the oxide thickness differences, the contact hole etch will not etch through the field oxide over the region 14. The etching will leave an oxide thickness of approximately 3500 Angstroms overlying the region 14, which is considerably thinner than that over the other portions of the device
32.

The thin oxide region enhances the tendency of the emitt...