The relentless shrinking of silicon components has led to exponential improvements in chip performance, but we’re beginning to hit physical limits. Now researchers have developed a strategy to integrate materials just 10 atoms thick into conventional chips.
For a long time, rapid advances in miniaturization meant the variety of transistors on a microchip doubled roughly every two years, a phenomenon dubbed Moore’s law. But as these components began reaching dimensions of just just a few nanometers, progress began to stall.
This left researchers and chip firms casting about for brand new ways to squeeze computing power into ever smaller spaces. So-called “2D materials” are a promising way forward. These crystalline structures are only just a few atoms thick and exhibit exceptional electronic capabilities.
To this point, it’s been difficult to integrate such exotic materials into conventional electronics. But now researchers at Fudan University in China have created a chip that mixes a memory core made from the 2D material molybdenum disulfide (MoS₂) with CMOS circuits.
“This work provides a promising technical pathway to bring promising 2D electronics concepts to real-world applications,” the authors write in a paper in regards to the recent process published in Nature.
The most important reason it’s been hard to mix 2D materials and standard chips is that the rough surface of conventional silicon circuits prevents them from adhering evenly and might damage their atomically thin layers.
To get around this, the researchers developed a fabrication method they call ATOM2CHIP, which introduces an ultra-smooth glass layer between the 2D material and the silicon. This provides each a mechanical buffer and a strategy to electrically isolate the MoS₂ layer from the electronics.
The team used the brand new method to create a flash memory array composed of a 10-atom-thick MoS₂ layer stacked on a 0.13-micrometer CMOS platform accountable for transmitting instructions to program, read, and erase the memory.
The chip could program bits in 20 nanoseconds and consumed just 0.644 picojoules per bit—significantly less energy than conventional flash memory. An accelerated aging test showed it could also retain data for greater than 10 years at 55 degrees Celsius. Programming accuracy was only 93 percent, which is well below what you’d expect from a industrial chip but still promising for an early prototype.
Kai Xu at King’s College London, told Recent Scientist the ultrathin design may additionally help solve a long-standing problem in silicon electronics—signal leakage. Transistors work through the use of a “gate” to manage when current flows through a channel, but as they get smaller it’s easier for current to slide through that barrier.
This implies they’re never truly off, which ends up in extra power consumption and noise that may interfere with nearby signals. However the physics of 2D materials mean transistors made with them have rather more effective gates, providing an almost perfect on/off switch.
“Silicon has already hit obstacles,” said Xu. “The 2D material might give you the option to beat those effects. If it’s very thin, the control on the gate may be more even, may be more perfect, so there’s less leakage.”
One significant challenge for the approach is that the glass layer central to the technique isn’t yet compatible with standard fabrication lines. “It is a very interesting technology with huge potential, but still a protracted strategy to go before it’s commercially viable,” Steve Furber on the University of Manchester told Recent Scientist.
Nonetheless, the work suggests that if we wish to kickstart Moore’s law, we could also be higher off abandoning the seek for ever smaller transistors and as an alternative concentrate on ever thinner chips.