Weebit Nano and SkyWater Churn Out First Batch of ReRAM Demo Chips
SkyWater produced the first silicon wafers integrating Weebit’s embedded ReRAM, marking a major milestone toward ReRAM commercialization.
SkyWater Technologies has completed the first demo batch of Weebit Nano’s ReRAM chip designs and is now moving toward qualifying them for early 2023.
The demo chips encapsulate Weebit Nano’s ReRAM in a 256 kb array, a RISC-V microcontroller, and other interfaces and peripherals required for embedded systems applications.
The Weebit Nano/SkyWater Technology ReRAM test chip. Image used courtesy of Weebit Nano
Weebit Nano is an Israeli semiconductor company founded in 2015 that specializes in Resistive Random Access Memory (ReRAM), a form of non-volatile memory (NVM) the company expects to eventually outpace flash memory in various applications ranging from IoT to artificial intelligence.
SkyWater Technologies is a semiconductor fabrication foundry that offers a Technology-as-a-Service business model to partners, specifically focusing on ways to innovate in silicon production without having to continue to push the limits of Moore’s law. Steve Kosier, CTO of SkyWater Technologies, spoke about the company’s production capacity on the Moore’s Lobby podcast titled, "US Semi Fab SkyWater Seeks to Co-innovate in Quantum, Photonics, and…Free Silicon?".
An Intentionally Scalable Model
Weebit Nano and SkyWater Technology announced their collaboration in Sept. 2021, making the turnaround time for demo chips exceptionally fast. SkyWater Technology’s existing 130nm CMOS S130 process flow made them ideal partners.
“We were fortunate to have ReRAM experience at SkyWater through our DARPA 3DSoC project, and so were well familiar with the processing needs and challenges of the technology,” Kosier told All About Circuits in an email.
SkyWater's Technology-as-a-Service model. Image used courtesy of SkyWater Technology
SkyWater Technology is not only fabricating the chips but working with Weebit Nano to fully integrate their chips into sub-modules and deliver them to potential customers to demo. Additionally, SkyWater Technology may scale the chips to a 90nm carbon nanotube CMOS process in the future.
“We engaged with Weebit to do the technology transfer and integration and support the rollout of the technology to our broad customer base,” said Kosier.
Many innovative types of memory require new and specialized methods or equipment to fabricate, limiting the ability to mass produce. Weebit Nano intentionally selects the most common materials and designs that can be supported by readily-available fabrication equipment to lower the barriers to production.
The Promise of ReRAM
Weebit Nano highlights some key advantages of ReRAM NVM, including improved endurance, robustness to its environment, low power consumption, and high speed.
In terms of endurance, the company claims that ReRAM experiences a 10–100x improvement in endurance over traditional flash, with ReRAM withstanding up to one million write cycles compared to 10,000 program/erase cycles in traditional flash. Additionally, access time is claimed to be 100x faster compared to flash memory. Data logging is one application where ReRAM can benefit from these characteristics.
ReRAM is also robust against its environment, including high temperatures and radiation. Weebit Nano claims that data can be stored for up to 10 years at 175°C or 20 years at 125°C. It is also reported to be 350x more resistant to radiation than flash memory. This makes the device a potential candidate for use in aerospace applications.
Weebit Nano ReRAM memory retention in temperature vs. years. Image used courtesy of Weebit Nano
ReRAM is also reported to be more power efficient than embedded flash memory and can be incorporated using backend-of-line (BEOL) manufacturing, increasing integration flexibility. Once again, this is an advantage over flash memory, which uses frontend-of-line manufacturing.
ReRAM, a BEOL manufacturing technology, integrates easily with any FEOL technology. Image used courtesy of Weebit Nano
Weebit Nano also claims ReRAM has potential applications in neuromorphic computing since ReRAM can act as a computing device as well. The company has partnered with CEA-Leti in the past to demonstrate how ReRAM can be used in spiking neural networks.
What’s Next for the Collab
After the demo chips are qualified in early 2023, Weebit Nano and SkyWater Technology will work on IP blocks that can be used by future customers and partners in their designs.
“The IP blocks of different array sizes are under development. Weebit Nano will release these for designers in the coming quarters”, said Kosier.