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With a drop of liquid, IBM develops a new microchip switch

Ionic liquids can switch the state of a metal oxide from conducting to insulating and back again, something that could be useful for computer processing and memory.

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On the left of this diagram, a droplet of ionic liquid rests atop a processing element. On the magnified view at right, the circuitry elements include the electrical source at left, the drain at right, and four diagnostic contacts coming from the top and bottom.
On the left of this diagram, a droplet of ionic liquid rests atop a processing element. On the magnified view at right, the circuitry elements include the electrical source at left, the drain at right, and four diagnostic contacts coming from the top and bottom. IBM

IBM has come up with a new technique for making the tiny switches and memory cells at the heart of computer chips: a drop of ionic liquid.

The technique converts a metal oxide on a computer chip from a conducting to an insulating state and back again, a transition that, using a different approach, is at the heart of conventional semiconductor chips today. Insulators don't conduct electricity and conductors do, so changing a material's state is instrumental to how it performs the logical operations of computer processing.

Today's semiconductor chips work by applying electrical voltage to a "gate," a semiconductor region that controls whether current flows from a source to a drain. IBM's approach uses a tiny droplet of an ionic liquid electrolyte instead -- about a cubic millimeter. Ions are atoms or molecules with a positive or negative charge, and they impart that charge to the liquid.

In IBM's technique, described this week in a paper in the journal Science, a positively charged droplet converts a vanadium oxide from an insulator to a conductor. And a negatively charged droplet reverses the process.

The technology could eventually be used either for processing or for nonvolatile memory, a type of data storage that retains information even without electrical power, IBM said in an announcement today.

IBM's approach to building a processing element uses an ionic liquid to control whether a metal oxide conducts electricity or instead insulates.
IBM's approach to building a processing element uses an ionic liquid to control whether a metal oxide conducts electricity or instead insulates. IBM

It's just research that's far from any actual working practical device, but Stuart Parkin, an IBM fellow at IBM Research, is willing to hold out the potential that it could help work around the difficult years ahead for Moore's Law, which faces challenges in shrinking computer circuits smaller and in getting them to run faster.

"Our unique ability to understand and control matter at molecular dimensions enables us to come up with new materials that could one day stand in for silicon based technologies," Parkin said in a statement. "We're writing a new chapter in the future of computing with innovations -- including looking beyond traditional electrically charge-based devices -- to prevent the industry from hitting a technology brick wall."

This isn't the only work in the area, called ionic liquid (IL) gating, but IBM said its approach takes new strides in stability, with the vanadium oxide maintaining its state even when the liquid is removed.