Browse Prior Art Database

Monitoring of Leakage Induced Threshold Shift

IP.com Disclosure Number: IPCOM000087995D
Original Publication Date: 1977-Apr-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Huang, YS: AUTHOR

Abstract

Forward-bias-induced threshold shift may be used to provide acceleration of leakage-induced threshold shift, as reported by T. H. Ning et al in Applied Physics Letters, Vol. 29, No. 3, August 1, 1976, pp. 198-200.

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Monitoring of Leakage Induced Threshold Shift

Forward-bias-induced threshold shift may be used to provide acceleration of leakage-induced threshold shift, as reported by T. H. Ning et al in Applied Physics Letters, Vol. 29, No. 3, August 1, 1976, pp. 198-200.

This technique utilizes a forward-biased p-n junction diode on the semiconductor surface near the MOSFET (metal-oxide semiconductor field-effect transistor) under stress, as shown in the figure. The injected minority carriers diffusing to the channel region of the biased MOSFET are of greater magnitude than normal junction leakage current density, and stress time, normally over hundreds of hours, may be reduced greatly. The density of minority carriers can be conveniently controlled by adjusting Vf, or If when a current source (not shown) is used.

Experimentally, one measures a forward-bias leakage-induced threshold shift of Vt1-Vt0 between time t0 and t1 equal to: (Pinj/CI) x (Ir/Ajct) (t1-t0), where Pinj = emission probability of carriers into gate insulator,

CI = equivalent gate insulator capacitance per unit area,

Ajct = total junction area of the MOSFET under stress, and

Ir = DC current picked up by both source and drain of MOSFET during stress.

Under normal leakage conditions, the threshold shift observed will be a similar function of the normal leakage current, I1. The experimental forward-bias (FITS) and leakage-induced threshold shift (LITS) are therefore related as follows: [(Vt1-Vt0)/(t1-t0)]LITS...