Correlated Electron Switches
Correlated Electron (Ce) switches operate via strong electron orbital interactions, with a key example being the predictions of metal-insulator transitions by Nobel Laureate Neville Mott over 70 years ago. The field of correlated electronics promises a wide range of highly disruptive characteristics to both commercial microelectronics and military readiness applications including memory, RF, logic and opto-electronics. A key roadblock has been finding practical Ce materials and properly integrating them into electrically switchable devices that are compatible with the semiconductor industry. Cerfe Labs has new Ce materials and devices which will break through this roadblock and deliver the promise of this exciting new class of electronics.
A better memory
The semiconductor industry has invested billions of dollars in emerging memory technologies, because virtually every system today is limited in some way by the underlying memory technology. A Correlated Electron device offers tantalizing capabilities as a non-volatile memory element (CeRAM) to move past many of these limitations. Key characteristics of our electron orbital switches used as CeRAM include:
- Ultimate low-cost: With a single material deposition step that can even be spun-on to a wafer, CeRAM can make non-volatile memory (NVM) accessible to the most cost-sensitive edge IoT applications. But CeRAM can also be made with more precise vapor deposition or atomic layer deposition techniques, and combined with ability to scale to at least 3nm CMOS in dimension, support Multi-Level Cell (MLC) in those tiny bit cells, and flexibly stack in 3D due to its non-polar programming and erase, CeRAM can take NVM density far beyond where it is today.
- Ultra- fast switching speed: CeRAM is too fast for our early test chips. We have confirmed 2nS read and write, but most Ce materials switch in under 100 femtoseconds.
- Unparalleled temperature range of operation: Electron orbital switches are adiabatic, and our CeRAM devices operate down to very low cryogenic temperatures, and they also retain state at temperatures above other technologies (we have yet to test to the device limits either direction). Based on temperature capability alone, we expect CeRAM to enable new microelectronics applications that do not currently have an NVM option, from the cryo/quantum realm on the cold side to automotive, space, and power electronics on the hot side. And in what would be a new luxury to circuit designers, within a normal commercial operational range, the resistance characteristic of CeRAM is invariant across temperature.
- Low voltage, low current operation: The “forming-free” (non-filamentary) CeRAM can be made to switch entirely below 0.6V, distinguishing it from all other known NVM technologies as natively compatible with advanced CMOS logic transistors. Combined with reasonable switching currents and ultra-fast switching, CeRAM offers the potential for ultra-low energy NVM.
- Integration compatible to CMOS: CeRAM can be made with a variety of materials in both the switching layer itself and the electrodes it attaches to, and furthermore CeRAM devices are natively compatible with CMOS process integration, meaning that it does not require excessive process temperature, or new process techniques, and it can happily withstand any subsequent temperature cycles such as solder reflow.
- Resistance tuning: In order to operate at optimal speed and energy, a resistive memory element’s high and low resistance states must be matched to the access transistors available. CeRAM resistances can be flexibly tuned to pair with any CMOS process node, including future CMOS nodes.
- Immunity to disturb. The physics CeRAM strongly suggest that it is immune to a wide variety of disturb, from current or voltage disturbs that can be security risks, to magnetic immunity important to many applications, and well as immunity to ionizing radiation, which is important to data centers as well as space/aeronautical applications.
- Reliability: Electron orbital switching does not have a wear-out mechanism.
Importantly, CeRAM delivers all of the impressive characteristics above without requiring any tradeoffs. This is not the case for other NVM technologies.
Other Correlated Electron Switch applications
The entirely new switching physics that has been harnessed in these new materials begs investigation into a wide variety of additional applications beyond memory. These include analog neuromorphic applications, RF applications, sensors and even “beyond CMOS” switches. Correlated electronics is an exciting emerging field requiring new understanding of physics of operation, and we hope our new Ce materials will eventually seed a research ecosystem to unlock the many novel capabilities. Our advanced Ce device development experience, commercial application experience, and our history of academic partnership from our past roles at Arm Research make us uniquely positioned to help enable this long term goal, which strongly aligns with initiatives in many countries targeted toward reinvigorating the microelectronics field with “beyond Moore” options.
Technologies other than Correlated Electron Switches
Cerfe Labs has several other technologies in earlier stages of development that we feel are as exciting as our Correlated Electron technology and expect to make additional announcements soon.