Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!uunet!mitel!sce!cognos!geovision!gd
From: gd@geovision.uucp (Gord Deinstadt)
Newsgroups: comp.arch
Subject: Re: FRAM
Summary: Not out yet, but coming
Message-ID: <661@geovision.UUCP>
Date: 8 Jun 89 23:21:15 GMT
References: <8YWwgEy00WBn01718g@andrew.cmu.edu>
Reply-To: gd@geovision.UUCP (Gord Deinstadt)
Organization: GeoVision Corp, Ottawa, Canada
Lines: 52

In article <8YWwgEy00WBn01718g@andrew.cmu.edu> zs04+@andrew.cmu.edu (Zachary T. Smith) writes:
>
>Hi, I have a question about a form of EEPROM/RAM
>that I heard about going on one year ago, called some-
>thing like Ferromagnetic RAM; I don't remember exactly.

 Ferroelectric RAM.  The usual silicon dioxide insulator in the RAM cell
 is replaced or augmented with a ceramic such as lead-zirconinium-titanate
 (PZT).  This is a non-linear dielectric with hysteresis; in effect,
 the crystal structure is altered by the applied electric field (yes
 it is a piezoelectric material) and it stays altered until an electric
 field is applied in the other direction.  While in the altered condition
 it emits an electric field, just like a permanent magnet emits a magnetic
 field.  Therefore this memory is NON-VOLATILE!

>
>What I want to know is:
>
>Do these parts exist?? What kind of r/w access times
>can I expect on them, and where can I get them?

 As far as I know they exist only in the laboratory right now.  Two
 small companies are pursuing them.  One company has licensed the 
 technology to ITT in Europe.  ITT wants to use them in digital
 TVs.  I don't think they really care about the non-volatility; they
 are more interested in the fact that PZT has a much higher dielectric
 constant than SiO2, giving a higher capacitance in each RAM cell.
 This makes it much easier to scale down the cell size for higher
 density.  I believe it's a factor of about 6 improvement, meaning
 you can go right to the next-generation (4 times denser) without
 doing much else besides just shrinking the transistors.

>Are they pin compatible with std. SRAM I.C.s?

 I imagine they will be.  I also expect that in five years the standard
 DRAM technology *will* be ferroelectric.  The major chip companies all
 ho-hummed at the announcements, but I think once they see some real
 parts out there they will switch over pretty quickly.  ITT reports
 that it is pretty easy to convert standard production lines to make
 FRAMS.

>Thanks in advance,
>
>Zach Smith (zs04@andrew.cmu.edu)

 You're welcome.

 Gord "I LIKE FRAMS" Deinstadt      gdeinstadt@geovision

 BTW, the name for a thing that has a permanent electrostatic field,
 without actually having any voltage on it, is an "electret".
 You may have heard of an "electret microphone".