Imec develops round gate nanowire transistors

Employees of the Leuven-based research institute Imec have made transistors based on nanowires in which the gate completely encloses the nanowire. This type of transistor would be a good candidate for chip production at 5nm.

The new transistors, called gaa-nwfets, can be produced both horizontally and vertically. Gaa-nwfets is an abbreviation of gate all around nanowire field effect transistors. They can be manufactured in simple steps and offer good electrical properties, such as low noise, and thanks to their junction-free design, they are simple and robust to manufacture. In addition, they would have low leakage currents, a property that already provides significant energy savings in trigate transistors. Many transistors use junctions, or transitions, between negatively and positively charged semiconductors, so-called np or pn junctions.

The nanowires in the gaa-nwfets are tuned for the desired performance by doping and sizing. They can therefore not only be used for processors and memory, but also for analog and RF applications. For use in SRAM cells, the imec researchers have devised a new structure that uses two stacked vertical transistors with the same channel doping. That could reduce the size of SRAM cells by 39 percent over traditional builds, allowing for higher densities. Both the horizontal and vertical transistors can be made together on a 300mm silicon wafer.

The evolution from planar to gate all around transistors