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From: pcg@aber-cs.UUCP (Piercarlo Grandi)
Newsgroups: comp.arch
Subject: Re: FRAM
Summary: Ferroelectric is GREAT, but politics, ....
Message-ID: <1012@aber-cs.UUCP>
Date: 13 Jun 89 14:47:56 GMT
Reply-To: pcg@cs.aber.ac.uk (Piercarlo Grandi)
Organization: Dept of CS, UCW Aberystwyth
	(Disclaimer: my statements are purely personal)
Lines: 46

In article <661@geovision.UUCP> gd@geovision.UUCP (Gord Deinstadt) writes:
    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!

I had read many years ago (around 1981) an article in Electronics on ferroelectric
memory. It is the invention apparently of a single person (an old style
inventor?), and was developed in coolaboration between him and some West
Coast govnt. lab. They had an argument on it (he alleged they wanted exclusive
rights for peanuts or else...), and this set back the entire idea.

Ferroelectric is a misnomer; from what I remeber a certain *potassium*
compound has a rombohedrical crystalline structure; one of the electrons can
be indifferently in either apex of the rombohedron, and can be moved or
detected from one to another by electric field. Once moved, it stays there,
so it is not volatile.

The advantages are: high noise immunity, very low power dissipation (none on
standby), which means that multilayer (i.e. 3D) memories are possible, and
almost infite scalability (down to the single crystal cell), the limit being
the resolution of the electric grid.

It is therefore an old technology, and I haave been hoping for the last ten
years that it comes of age. Before these, the most recent news were that
the technology had been licensed by Australians, in a hope to leapfrog
current technology and build an indigenous industry around them.

If FERAMs become common, the impact on architectures will be very profound.
Just think of 3D layering, and non volatility. Mass storage, even more than
core storage, could be swept away... (wishful thinking probably, but who
knows...).
-- 
Piercarlo "Peter" Grandi           | ARPA: pcg%cs.aber.ac.uk@nsfnet-relay.ac.uk
Dept of CS, UCW Aberystwyth        | UUCP: ...!mcvax!ukc!aber-cs!pcg
Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk