
Chipmakers Test Ferroelectrics as a Route to Ultralow-Power Chips - rbanffy
https://spectrum.ieee.org/computing/hardware/chipmakers-test-ferroelectrics-as-a-route-to-ultralowpower-chips
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xt00
Supriyo Datta is a pretty top level semiconductor theory guy, so its a good
chance theoretically this could work, but the place where tons of issues have
come up over the years in using new materials is that they often lead to
quality or defect issues in the manufacturing process that takes years to
figure out.

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deepnotderp
Fwiw, Chenming Hu is a proponent of NC-FETs as well.

Also, GloFo has already fabricated FinFET NC-FETs.

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xt00
oh interesting, was not aware of the term NC-FET -- so basically the
ferroelectric material gives it the negative capacitance behavior...
interesting.

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deepnotderp
Yup, the NC-FET essentially has the NC and positive capacitor in series to get
a voltage amplifier, a clever way of subverting the Boltzmann limit :)

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baybal2
>Some researchers have predicted that transistors built with ferroelectrics
will never exceed 100 megahertz. And some think that building these devices
will require very thick layers of ferroelectrics—too thick to be practical.

Wast amounts of low power MCUs are still built to function in single MHzs. A
jump from milliamps to microamps is not a small deal.

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userbinator
Less than 1MHz is also very common - some MCUs have the option of running from
the 32kHz RTC oscillator in low-power modes.

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Lind5
Momentum is definitely building on this, although still very much in the R&D
phase [https://semiengineering.com/a-new-memory-
contender/](https://semiengineering.com/a-new-memory-contender/)

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pjc50
I wonder how this is related to Ferroelectric RAM, which offers nice
properties along all axes except density?

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deepnotderp
So in NCFETs there is something called capacitance matching which is basically
the value of the negative capacitor compared to the value of the positive
capacitor.

When you have different values, then you can get NCFETs, and in different
values, you get FRAM.

In FRAM you get states stored in the polarization of the atoms in the
ferroelectric layer.

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hoosieree
Is anyone putting R&D into this besides Global Foundries? I've seen their name
pop up in every spintronics announcement lately.

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zitterbewegung
Probably not since there aren't enough competitors left to actually invest in
chips. If you don't hear Intel, TSMC or Global Foundaries putting R&D into
something then you have the way out there research of academia.

Maybe a random startup or two are investigating this but those are academics
that figured something out from a grant and are attempting to make a company
out of it. The road to beating silicon is a long one.

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teemwerk
TI and Cypress through Ramtron has done quite a bit of work incorporating
ferroelectric materials into CMOS processes and such for FeRAMs mostly.
Obviously RAMs are not transistors but the work is certainly relevant. Like
the article says, the large feature size for ferroelectrics has mostly been
the limitation for ferroelectric applications.

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lightedman
Sure, you can reduce the voltage required, but what about the current
required? Ferric materials tend to be somewhat resistive compared to most
other metals.

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tedsanders
The ferroelectric materials here are used in the insulating stack, so actually
higher DC resistance is a good thing.

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slededit
DDR4 on chip frequencies are on the order of 200mhz internally. They get the
high data rates by being massively parallel. So never discount the low clock
frequencies.

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deepnotderp
It's a moot point anyways since hafnia based ferroelectrics do not suffer from
this speed issue. Also this is the _transistor_ switching speed we're talking
about, entirely different than DDR clock speeds.

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slededit
Transistor speed is actually the problem on DRAM memories. The process for
making great capacitors is terrible for making fast transistors.

~~~
deepnotderp
But DRAM processes use RCAT transistors.

