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Completely Electrically Reprogrammable Nonvolatile Memory Device Using Conventional P Channel MOSFET

IP.com Disclosure Number: IPCOM000089394D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 34K

Publishing Venue

IBM

Related People

Ning, TH: AUTHOR [+2]

Abstract

A previous publication [*] described a nonvolatile memory device using trapped holes in SiO(2) and techniques for injecting holes into SiO(2) by (a) electrical injection for devices having an underlying injecting junction and (b) optically induced injection for devices without an underlying injecting junction. Electrical erasure by avalanche injection of electrons is also described.

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Completely Electrically Reprogrammable Nonvolatile Memory Device Using Conventional P Channel MOSFET

A previous publication [*] described a nonvolatile memory device using trapped holes in SiO(2) and techniques for injecting holes into SiO(2) by (a) electrical injection for devices having an underlying injecting junction and (b) optically induced injection for devices without an underlying injecting junction. Electrical erasure by avalanche injection of electrons is also described.

In the present article, a method is described for electrically and uniformly injecting holes into the gate SiO(2) layer of a p-channel MOSFET without requiring any injecting junction. Thus, this method, together with the avalanche electron injection for erasure, turns a conventional p-channel MOSFET into a completely electrically reprogrammable nonvolatile read-only memory device, with no dual-dielectric or floating gate require.

One way to electrically inject holes from the silicon substrate into the gate SiO(2) layer of a p-channel MOSFET is as shown schematically in Fig. 1. When the substrate bias is zero, the energy-band diagram is as shown in Fig. 2A. There is a depletion layer of width X(m0). When the substrate voltage is pulsed to some positive value, then the substrate is reverse biased with respect to the source and drain diffusions and the depletion layer widens to X(m1), as illustrated in Fig. 2B. The majority carriers (electrons in this case) originally located between x = X(m0) and x = X(m1) are now swept towards the substrate. As these majority carriers move towards the substrate, they gain energy from the field in the depletion region. If the substrate voltage pulse is large enough, some of these majority carriers may pick up enough energy to impact ionize near x = X(m1), thus creating secondary electron-hole...