Browse Prior Art Database

MNOS Varactor Bootstrap Memory Cell

IP.com Disclosure Number: IPCOM000083137D
Original Publication Date: 1975-Apr-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 19K

Publishing Venue

IBM

Related People

Lee, HS: AUTHOR

Abstract

This single field-effect transistor (FET) memory cell has a nonvolatile metal-nitride-oxide semiconductor (MNOS) capacitor coupled between the gate and the drain of the field-effect transistor, so that the memory states of the cell can be distinguished by whether or not the read operation is aided by bootstrapping of the transistor through the capacitor.

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MNOS Varactor Bootstrap Memory Cell

This single field-effect transistor (FET) memory cell has a nonvolatile metal- nitride-oxide semiconductor (MNOS) capacitor coupled between the gate and the drain of the field-effect transistor, so that the memory states of the cell can be distinguished by whether or not the read operation is aided by bootstrapping of the transistor through the capacitor.

As shown in the figure, the memory cell comprises a FET 10 having a gate electrode 11 and a drain electrode 12 with an MNOS variable capacitor 13 coupled between the gate and drain. By providing an MNOS nonvolatile varactor capacitor between the gate and drain of the device, nonvolatility of the cell is built into the varactor and not into the FET itself. The MNOS capacitor 13 has a semiconductor side s coupled to drain 12 and its metal side m coupled to gate
11.

The logic states 1 and O provided in such memory cells can be distinguished by whether the read operation is aided by the bootstrapping or not aided by the bootstrapping. In this way, a cell can be read in an extremely fast manner while eliminating the transconductance degradation of the write-erase cycles, and at the same time provide a low-state threshold which does not effect the cell operation.

The circuit further avoids the restrictions of window size and position toward obtaining the large sense signal, by transmitting the gate drive through the MNOS capacitor rather than across it. Also a larger sense signal wi...