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Browse Prior Art Database

MOSFET Read Only Storage Cell

IP.com Disclosure Number: IPCOM000073467D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Linton, RH: AUTHOR

Abstract

Data is stored in this monolithic read-only storage cell by the breaking down of oxide insulation layer of capacitor C1. When the capacitor C1 has been broken down, signals put on word line 10 will be transmitted to the bit line 12 by the conduction through FET 14 to ground. When capacitor C1 has not been broken down, FET 14 will not conduct irrespective of the data applied to word line 10.

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MOSFET Read Only Storage Cell

Data is stored in this monolithic read-only storage cell by the breaking down of oxide insulation layer of capacitor C1. When the capacitor C1 has been broken down, signals put on word line 10 will be transmitted to the bit line 12 by the conduction through FET 14 to ground. When capacitor C1 has not been broken down, FET 14 will not conduct irrespective of the data applied to word line
10.

To break down the oxide insulation layer cell of capacitor C1 the word and bit lines 10 and 12 are selected and driven to approximately 20 volts. Then the ground line of the cell is driven to -30 volts placing 50 volts across the oxide capacitor C1 for the selected cell while maintaining the oxide voltage of the unselected cells below 30 volts. The oxide layer of capacitor C1 is selected so that its breakdown voltage is less than 50 volts and greater than 30 volts.

After the oxide breakdown has occurred, the diffusion side of capacitor C1 will continue to drop toward -30 volts until the substrate diode can turn on. The presence of the capacitors C GS1 and C GS2 in series will prevent a voltage greater than 30 volts either across C GS1 or C GS2 and cause them to break down.

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