Supercapacitor-On-a-Chip Now One Step Closer (ieee.org)

schwit1 writes: In 2010 Spectrum reported a new approach for creating chip-scale supercapacitors on silicon wafers, proposed by researchers at Drexel University in Philadelphia and the Universite Paul Sabatier in Toulouse, France. In an article published in Science, the researchers described how to make supercapacitor electrodes from porous carbon that could stick to the surface of silicon wafers so that they could be micromachined into electrodes for on-chip supercapacitors. Now the same team has finally succeeded in doing just that. In a paper published in this week's Science, researchers from the two initial teams report creating efficient porous carbon electrodes that really stick to the surface of a silicon wafer. They made layers of porous carbide derived carbon (CDC) that are completely compatible with all treatments used in the semiconductor industry, says Patrice Simon, a researcher at Universite Paul Sabatier who has researched porous CDC electrodes over the last ten years and co-authored both the 2010 and this week's paper in Science.

Comments

And?

[mariox19]

Is it too much to ask for a "And why this is a big deal" in the summary, or do I have to turn in my nerd card?

Re:And?

[U2xhc2hkb3QgU3Vja3M]

1 .Do you know what a chip is?
2. Do you know what a supercapacitor is?
3. Do you know where your towel is?

Re:And?

[Cassini2]

I'm not clear on this either. Why would someone want to build a large-area device, like a super-capacitor, on top of an IC? given that the cost per unit surface area of a modern IC is astronomical?

The question is particularly complex, as we are talking about super-capacitors. Super-capacitors usually have terrible AC characteristics. If we were talking about high-performance ceramic capacitors, then the answer would be to improve the AC performance of the power distribution net, or for RF communications.

Alternatively, the answer could be to power a portable device. However, a typical capacitor has such a large surface area that it is a roll (or a stack) of many layers. To power the portable device, the surface area of the chip would have to be very large relative to its power consumption. This would be an unusual combination, as power consumption is often a function of die surface-area.

In concept, any device will have an application. However, I'm not clear on what the application for this device would be ...

Re:And?

[peragrin]

This article Is about installing super capacitors on the board replacing regular capacitors. Not about replacing the battery

Re:And?

[Antique Geekmeister]

I can think of several good reasons. Decoupling the "droops" on the local power lines from local circuits drawing or providing excess current for signal lizes comes to mind immediately. It's easy to put in a large local capacitor to decouple many devices, but harder to find the board space to put a small, high frequency capable capacitor _right next to_ the power leads that connect each chip to the power bus or to the power plane.

I've seen a number of complex board designs ruined when a new engineer, or a middle manager, insisted on replacing a set of small capacitors with one large one. I've even myself had to wire in small capacitors, manually, on top of soldered in chips to provide the necessary decoupling. I'll also admit that that was decades ago: I don't have the eyes and hands for that kind of work anymore.

Re:And?

[fnj]

A supercapacitor is like a battery that can store 10 to 100 times more energy per unit volume

Utter and complete bullshit. No supercapacitor comes anywhere near the volumetric energy density of even a fair to middling battery.

You could have found this out in about 5 seconds, even if you are too ignorant to already know it.
Supercapacitor: 0.06-0.05 MJ/l
Lead acid battery: 0.56 MJ/l
Lithium-ion battery: 0.9–2.63 MJ/l

Re:And?

[Bengie]

Cost of an IC has no bearing on this. All they need to do is integrate them into the same package to reduce traces.

Re:And?

[Bengie]

That's also ignoring that as a cap loses power, the voltage goes down. Batteries have stable voltage output.

Higher capacitance per unit area

[XXongo]

I'm not clear on this either. Why would someone want to build a large-area device, like a super-capacitor, on top of an IC? given that the cost per unit surface area of a modern IC is astronomical?

Because a supercapacitor is not defined by being a large area. A supercapacitor can be any area.

Its defining characteristic is a higher capacitance per unit area than conventional capacitors. So, a supercapacitor is actually smaller area than the same capacitance in a conventional cap.

The question is particularly complex, as we are talking about super-capacitors. Super-capacitors usually have terrible AC characteristics.

Some, but not all, applications of capacitors require good AC characteristics.

too many links

[Gravis Zero]

there are too many links in the summary to bullshit that doesn't matter. seven links is to many. keep it down to one or two.

If I had to guess why this is a good thing...

[mykepredko]

At first thought, putting capacitors on the chip means that EVERYTHING for an application could be put on a piece of silicon and not require any interconnections. This could be very valuable for (very) high frequency RFID tags where the chip contains the logic, radio, antenna and power supply good for a few milliseconds of operation without any external components. This could easily halve (or more) the cost of an RFID tag and reduce it to just dropping a chip into the tag's (or even product's) plastic mold - it's been a number of years since I saw the state of the at on RFID tags, but they were to cost $0.15 to $0.25 each in quantity. Without any external parts, this cost could drop to a few pennies.

The other application I can think of are chips which need a defined power down sequence or else be damaged/lose data. The obvious example for this would be in a Flash chip with a write buffer - if power was lost, the contents of the write buffer would be saved to non-volatile storage before it was lost.

Others? I think the RFID tag is probably the application where this technology would be most valuable.