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Method of Reducing Programming Voltage for Non-Volatile Memory Devices

IP.com Disclosure Number: IPCOM000047531D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kotecha, HN: AUTHOR

Abstract

Variable threshold semiconductor memory devices such as the floating gate type described in [1,2] exhibit a decrease in floating gate charging current during constant voltage program biasing. Such devices can be programmed with lower maximum control gate voltages if the programming voltage is ramped to sustain constant gate current after the emission field is established. Floating gate memory devices which employ hot electron emission, or similar phenomena, in order to transfer charge to a floating gate electrode, experience a loss of gate charging current as the floating gate becomes charged, as first pointed out in [1]. This effect is caused by a retarding field established in the dielectric between the floating gate and the semiconductor substrate or other source of charge.

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Method of Reducing Programming Voltage for Non-Volatile Memory Devices

Variable threshold semiconductor memory devices such as the floating gate type described in [1,2] exhibit a decrease in floating gate charging current during constant voltage program biasing. Such devices can be programmed with lower maximum control gate voltages if the programming voltage is ramped to sustain constant gate current after the emission field is established. Floating gate memory devices which employ hot electron emission, or similar phenomena, in order to transfer charge to a floating gate electrode, experience a loss of gate charging current as the floating gate becomes charged, as first pointed out in [1]. This effect is caused by a retarding field established in the dielectric between the floating gate and the semiconductor substrate or other source of charge. In choosing a voltage to be applied to the control electrode when programming, an initial voltage is selected at which a predetermined emission, or gate, current will be established. Thereafter, the control electrode is increased at a rate at which the current to the floating gate will be maintained constant until the desired charge is accumulated on the floating gate to provide the necessary threshold voltage of the memory device. The programming of devices by the above technique enables lower control gate voltages to be used since a predetermined gate current can be obtained at minimum voltage. To account for process p...