Engineers Produce Smallest 3-D Transistor Yet

Estimated reading time: 4 minutes

Thinner, Better “Fins”

Using the technique, the researchers fabricated FinFETs, 3-D transistors used in many of today’s commercial electronic devices. FinFETs consist of a thin “fin” of silicon, standing vertically on a substrate. The gate is essentially wrapped around the fin. Because of their vertical shape, anywhere from 7 billion to 30 billion FinFETs can squeeze onto a chip. As of this year, Apple, Qualcomm, and other tech companies started using 7-nanometer FinFETs.

Most of the researchers’ FinFETs measured under 5 nanometers in width — a desired threshold across industry — and roughly 220 nanometers in height. Moreover, the technique limits the material’s exposure to oxygen-caused defects that render the transistors less efficient.

The device performed about 60 percent better than traditional FinFETs in “transconductance,” the researchers report. Transistors convert a small voltage input into a current delivered by the gate that switches the transistor on or off to process the 1s (on) and 0s (off) that drive computation. Transconductance measures how much energy it takes to convert that voltage.

Limiting defects also leads to a higher on-off contrast, the researchers say. Ideally, you want high current flowing when the transistors are on, to handle heavy computation, and nearly no current flowing when they’re off, to save energy. “That contrast is essential in making efficient logic switches and very efficient microprocessors,” del Alamo says. “So far, we have the best ratio [among FinFETs].”

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