Technical / research

Researchers from the Guizhou Institute of Technology in China produced RRAM devices using finely ground used egg shells. These devices were not very durable - they only lasted about 100 write cycles...

To create the devices, the researchers ground the egg shells until they got a 'nanoscale' powder. They then dried it and dissolved it in a solution. The solution was than used to coat a substrate to form the electrolyte part of the RRAM device.

A team of international researchers, from China (Nanyang Technological University), Singapore (NTU) and Germany (RWTH Aachen University and Forschungszentrum Juelich) developed a technique to turn RRAM chips into logic processors.

The researchers say that these kind of processors eliminate the need to transfer data between memory storage and the computational unit (as it is now the same unit) - and so these processors could be at least two times faster than current processors. The new processors will also be smaller than current designs.

Researchers from the Korea Advanced Institute of Science and Technology (KAIST) developed a security RRAM device that can be dissolved in water in less than 10 seconds. The idea, it seems, is that this kind of device can be disposed of quickly and safely.

The RRAM device was produced on a solid sodium glycerine (SSG) substrate, which is water soluble. The RRAM chip itself was deposited using an inkjet-printer.

Researchers from Leti presented a new paper that clarified for the first time the correlation between endurance, window margin and retention of RRAM. The researchers advice ways module these three key properties, in different RRAM types.

Each RRAM type and base material has a different "sweet spot" that offers the best performance in all three categories. Using modelling the researchers were able to address various non-volatile memory applications, targeting high speed, high endurance or high stability.

US-based RRAM developer 4DS Memory announced that it has measured the endurance yield of more than 1,000 cells of five different cell sizes on two different wafers, and more than 97% of the memory cells tested achieved the required endurance goal, significantly exceeding the target of 90% endurance yield.

4DS recently announced the fabrication of a working 40nm RRAM memory cell in collaboration with HGST, a subsidiary of Western Digital. The company also successfully completed a placement of $3 million USD.

Researchers from Stanford University are studying filament RRAM technologies to discover the fundamental behavior of these memory cells. The research team built a tool to measure the basic forces that make RRAM chips work - especially the heat requirements for RRAM switching.

Using micro thermal stage (MTS) devices, RRAM chips were studied under a wide range of temperatures, to try and find the exact temperature in which RRAM switching occurs. It was discovered that operating at 80 to 260 F is more efficient than the higher temperatures people thought were more efficient.

Researchers at the Chinese Academy of Sciences developed a new cation-based RRAM device in which a single layer graphene was used as an ion barrier. Experiments indicate that this device is more reliable than previous RRAM designs while still maintaining high performance.

This work follows a recent discovery by the research group that there is a competition between the SET and RESET process in cation-based RRAM, which causes failure of reset operation in the RRAM device. The researchers found that the active metal which forms a conductive filament can diffuse into the Pt electrode under the action of an electric field, and form an additional active metal source in Pt electrode, which caused the failure of reset operation. Using graphene as an ion barrier is a solution to this problem.

A couple of months ago, we reported that Israel-based RRAM developer Weebit Nano partnered with France-based research institute Leti, to co-develop advanced RRAM devices based on silicon oxide.

Weebit Nano now announced that its SiOx ReRAM memory technology has been successfully transferred from Rice University’s facilities to Leti’s pre-industrialisation facility in Grenoble, France. Leti's initial experiments confirm that Weebit’s unique nano-porous SiOx process is reproducible.

Australia-based RRAM developer 4DS Memory announced that it developed a working 40nm RRAM memory cells. This was achieved in collaboration with HGST, a subsidiary of Western Digital.

The 4DS memory cell is constructed using an advanced perovskite material, which has the same crystal structure as the inorganic compound calcium titanium oxide. The cells have no filaments and are so easier to scale compared to filamentary RRAM.

Israel-based RRAM developer Weebit Nano announced that it partnered with France-based research institute Leti. Leti and Weebit Nano will work on advanced RRAM devices based on silicon oxide.

As part of that agreement, Weebit will gain access to the advanced facilities of Leti, including an 8,500 square meters semiconductor cleanroom area.