Browse Prior Art Database

EEPROM Cell for Low Power and High Density Application

IP.com Disclosure Number: IPCOM000109664D
Original Publication Date: 1992-Sep-01
Included in the Prior Art Database: 2005-Mar-24
Document File: 3 page(s) / 81K

Publishing Venue

IBM

Related People

Hsu, CH: AUTHOR [+2]

Abstract

Disclosed is a method to fabricate EEPROM cell with butted source/ drain contact for low power and high density application. This method utilizes p-channel device and low coupling factor between control and floating gates to achieve high programming and erasing speed, while maintaining stability of bottom gate oxide.

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EEPROM Cell for Low Power and High Density Application

       Disclosed is a method to fabricate EEPROM cell with
butted source/ drain contact for low power and high density
application.  This method utilizes p-channel device and low coupling
factor between control and floating gates to achieve high programming
and erasing speed, while maintaining stability of bottom gate oxide.

      The conventional EEPROM or Flash cell uses channel hot electron
injection into the floating gate from the drain depletion region of
n-channel device as a programming technique.  In order to obtain
sufficiently injected electrons, high voltages are required for the
drain and gate.  Therefore, huge power consumption takes place during
programming cycle.  To obtain a high gate voltage, a large coupling
factor between the control and floating gate is required, which would
cause poor electron tunneling efficiency from floating to control
gate and possible tunneling from substrate to the floating gate
during erase.

      This invention takes advantage of the significant hot electron
injection at low gate voltage in p-channel device.  Using p-channel
device for EEPROM cell enables the following features to be
implemented and thus achieves high programming and erasing speed
while maintain gate oxide stability and high density.  The control
gate overlaps the floating gate over shallow trench to provide small
coupling factor and allows butted source/drain contact which results
in a...