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Read Only Metal Ferroelectric Semiconductor FET Memory Element

IP.com Disclosure Number: IPCOM000077462D
Original Publication Date: 1972-Aug-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Jacobs, JT: AUTHOR [+3]

Abstract

A read-only memory system is described. This system gives a method by which different programs may be stored on silicon or semiconductor wafers, with only the last two metalizations being unique. The memory incorporates the contact potential difference as a method of retaining the polarization state in a metal-ferroelectric semiconductor field-effect transistor (MFES FET).

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Read Only Metal Ferroelectric Semiconductor FET Memory Element

A read-only memory system is described. This system gives a method by which different programs may be stored on silicon or semiconductor wafers, with only the last two metalizations being unique. The memory incorporates the contact potential difference as a method of retaining the polarization state in a metal-ferroelectric semiconductor field-effect transistor (MFES FET).

A built-in field exists between a metal-ferroelectric semiconductor sandwich when the work functions of the metal and the semiconductor are different. This field is sufficient to cause the ferroelectric to pole in a given direction. The equilibrium value of the polarization is determined by the cancellation of the built- in field by the depoling field. Therefore, each built-in field will have a unique equilibrium value of polarization. The value and sign of this built-in field can be altered by using metal contacts with different work functions.

A MFES FET is analogous to a metal-oxide semiconductor (MOS) FET when the oxide layer is replaced by the ferroelectric. By putting top electrodes of different work functions on the FE, different equilibrium polarization states can be achieved. At the semiconductor ferroelectric interface the compensation charge for the polarization resides in the semiconductor. A compensation charge which corresponds to accumulation will cause a high-conductance channel, while a compensation charge of the re...