Startup Demonstrates ReRAM Retention, Endurance

　　An Israel-based semiconductor startup has reported positive results with its ReRAM technology.

　　Weebit Nano recently published preliminary evaluation results of endurance and data retention measurement on 4Kb arrays on 300nm cells. In a telephone interview with EE Times, CEO Coby Hanoch said the results successfully conclude the 300nm 4Kb characterization. The measurement was done under a variety of temperature and duration conditions at 150, 200 and 260 degrees Celsius, monitoring the ability of the ReRAM cells to maintain their resistivity levels within industry acceptable ranges.

　　Hanoch said 260 degrees Celsius is significant since it's the temperature used when soldering chipsets into printed circuit boards. Weebit Nano's 4Kb array kept its programmed data after 30 minutes at 260°C, exceeding the soldering requirement of 15 minutes at this temperature. This allows several soldering cycles. Data retention lifetime extrapolation showed the ability to keep written data for 10 years at above room temperature, he added, and high enough to meet the requirements of market segments such as industrial and automotive.

　　Other endurance characteristics were done under various voltage levels and timing durations to assess the ability of the memory to endure multiple re-write cycles. Hanoch said the endurance results were significantly higher than the program/erase cycling of existing flash technology. It's preliminary yet encouraging data that's critical for Weebit's ReRAM manufacturability and product reliability, and ultimately, commercialization. He said the company is on track to achieve its goal of a 40nm working cell by the end of the year.

　　Hanoch credits Weebit's collaboration with Leti for the fast pace of its ReRAM development because of it's strong knowledge and expertise in memory technology. The 4Kb array reliability results were achieved in Leti's pre-industrialization facilities in Grenoble, France, and were conducted in parallel to the Weebit's 40nm SiOx ReRAM cell development. “We've been making excellent progress really fast," he said. “We've done in two years what's taken others seven to 10."

　　Weebit's formation is atypical as well. The company was started in 2015 by non-technical people who licensed technology invented by Professor James Tour of Rice University. Tour is renowned for his work in the field of materials engineering and nanotechnology. Hanoch said Weebit has secured several patents to ensure commercial and legal protection for its technology, and Tour has demonstrated non-volatile memory behavior with SiOx, the most common and lowest cost material in the semiconductor industry. In the beginning, the company struggled to get funding, so it went to the Australian Stock Exchange to do a reverse merger to become a public company.

　　Hanoch said the differentiator for Weebit's ReRAM technology is it's based on standard materials using silicon oxide and same machines that exist in commercial fabs. Using standard tools and procedures should enable the company to reach productization faster while getting high yields at a lower cost. “There lots of companies developing ReRAM technology and next generation memories, but in the vast majority of cases they are trying to use materials not used in fabs," Hanoch  said.

　　Jim Handy, principal analyst with Objective Analysis, said the fact that Weebit is using standard materials is a big plus. “One of the great difficulties with other emerging memory technologies is that most of them use new materials that are either poorly understood compared to silicon, which the industry has been working with constantly for over 50 years, or they attack the silicon substrate," Handy said.

　　Weebit's ReRAM progress is not dissimilar to Everspin's advances with embedded MRAM in collaboration with GlobalFoundries announced earlier this year. The companies outlined eMRAM's ability to retain data through solder reflow at 260 degrees Celsius, and for more than 10 years at 125 degrees Celsius, plus read/write with outstanding endurance at 125 degrees Celsius, enabling it to be used for general purpose MCUs and automotive SOCs.