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Reduced FET Leakage

IP.com Disclosure Number: IPCOM000079936D
Original Publication Date: 1973-Oct-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kump, HJ: AUTHOR

Abstract

This is a method of reducing field-effect transistor (FET) leakage through surface inversion under thick oxides on p-type substrates, by reducing the spacing between adjacent diffusions until the electron quasi-fermi levels of the diffusions merge.

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Reduced FET Leakage

This is a method of reducing field-effect transistor (FET) leakage through surface inversion under thick oxides on p-type substrates, by reducing the spacing between adjacent diffusions until the electron quasi-fermi levels of the diffusions merge.

FET leakage, both diffusion-to-diffusion and diffusion-to-substrate, has been associated with a charge induced inversion layer produced under thick oxides between devices. This inversion layer extends over the entire substrate, except in the vicinity of diffusions. Formed in conjunction with the inversion layer is a depletion region, which acts as an electron generator and source for current between the substrate and the diffusions. If the oxide charge is sufficiently great an electron bridge is formed between diffusions. The electron bridge interconnects all regions of depletion and, hence all electrons generated therein. Where voltages are applied to the diffusions, the depletion generated electrons are caused to flow along the inversion layer to one or more of the diffusions and a leakage current is said to result. The leakage from the diffusions may be reduced by reducing the spacing between diffusions, until the quasi-fermi levels of the diffusions merge with each other. The distance should be on the order of a few electron diffusion lengths. As the quasi-fermi levels merge, the inversion layer vanishes (for small oxide charge) and the interconnecting bridge is broken.

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