Microelectronics: Two at a time
New design reduces the areal footprint of nanowire transistors by a factor of two. Xiang Li at the A*STAR Institute of Microelectronics and co-workers have now integrated two transistors onto a single vertical silicon nanowire, pushing the areal density limit of nanowire transistors even further.
Semiconductor chip makers first began the production of three-dimensional (3D) transistors in 2011. Engineers can pack more 3D transistors onto a single chip because they are much more compact than traditional transistors.
For future generations of semiconductor chips, however, there is a need to shrink these 3D transistors further and the use of vertical nanowires in the transistor design is one of the promising approaches. Moreover, the area taken up by a nanowire-based transistor is typically half that of a planar transistor — or even less if considering more complicated components, like inverters. Xiang Li at the A*STAR Institute of Microelectronics and co-workers have now integrated two transistors onto a single vertical silicon nanowire, pushing the areal density limit of nanowire transistors even further.
The researchers used wrap-around gates, or ‘gate-all-around’ gates, in the making of their device. These gates consist of a vertical cylinder, at the center of which lies the nanowire. They are much better at controlling the transistor current than traditional planar gates. Li and co-workers decreased the area required for a gate-all-around nanowire transistor by a factor of two by constructing two transistors out of a single vertical nanowire. Their design involves two wrap-around gates, one above the other, separated by a thin dielectric layer to isolate them electrically (see image). Unlike other independent double-gate transistor designs, such as those employing a vertical fin-like channel, changing the gate voltage applied to one transistor does not change the threshold (or turn-on) voltage of the other. This means that either of the gates can modulate the nanowire current independently.
As a result, Li and co-workers were able to construct a simple logic device using just one nanowire. For a nanowire doped with negative carriers, current was able to flow when both gate voltages were high, but current stopped when either gate voltage was low. This device therefore functioned as an ‘AND’ digital gate, but used only half the area it otherwise would require. The stacked gate arrangement may also be useful for enabling an emerging type of transistor, called a tunnel field effect transistor (TFET). Because TFETs rely on the tunneling of electrons across a barrier rather than the thermal activation of electrons, they turn on very quickly and consume very little power. Li says the tunnel junction required for a TFET could be formed between the two gates of the dual-gate nanowire geometry, allowing a particularly compact implementation. The dual-gate design could also be used for other technologies, such as non-volatile memory.
The A*STAR-affiliated researchers contributing to this research are from the
Li, X. et al. Vertically stacked and independently controlled twin-gate MOSFETs on a single Si nanowire. IEEE Electron Device Letters 32, 1492–1494 (2011).
A*STAR Research | Research asia research news
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
Next-generation gravitational wave detector in space will complement LIGO on Earth
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...