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Browse Prior Art Database

Short Channel Field Effect Transistor

IP.com Disclosure Number: IPCOM000083180D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Abbas, SA: AUTHOR [+4]

Abstract

The threshold instability of an N channel field-effect transistor (FET), which is caused by hot electron injection, is reduced by varying the vertical doping profile in the channel.

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Short Channel Field Effect Transistor

The threshold instability of an N channel field-effect transistor (FET), which is caused by hot electron injection, is reduced by varying the vertical doping profile in the channel.

The threshold instability in FET's can be caused by trapping of hot electrons in the gate dielectric. This instability represents a serious reliability exposure for any high density or high-performance device. The hot electrons are generated through impact ionization in the drain depletion region. The amount of trapping is a function of the trap density in the gate dielectric and of the energy distribution of the hot electrons in the depletion region. Electrons above a certain energy (the barrier energy) will be injected into the conduction band of the gate insulator, and a certain fraction will be trapped in the insulation giving rise to the threshold shift.

The improved FET has a source region 10, a drain region 12 in body 14. Over the channel 16 is provided a conventional gate 17. As indicated, a region 18 of P-type impurity is introduced into the channel region 16 by ion implantation or other means. The implant profile is indicated by curve 20, which is a plot of channel doping versus depth within the FET in the channel region.

The electrons during operation will begin to create other hole electron pairs by impact ionization as in conventional FET's, but in this instance the action will take place a distance from the surface. The number of ele...