The computing industry faces constant demands to provide faster access to data and reduce power consumption. As current memory systems cannot meet these demands indefinitely, it is essential to develop entirely new technologies.
One strong contender is resistive random access memory (RRAM), which stores binary information by switching a dielectric material between conducting and non-conducting states.
A seamless transition to this new technology requires that RRAM memory cells be compatible with existing electronics, which are usually based on complementary metal oxide semiconductors (CMOS). Now, Xin Peng Wang and co-workers at the A*STAR Institute of Microelectronics, Singapore, have designed nickel-based electrodes that can couple RRAM to CMOS systems as well as reduce the current required to switch the RRAM between memory states1.
“One of the current most dominant memory systems, NAND flash, is expected to reach the limit of its scalability in 2017 or 2018,” says Wang. “We need to identify emerging non-volatile memory systems with higher densities, to make up the market. Recently, RRAM has attracted lots of attention due to its fast programming and erasing speeds, high endurance and good retention of data.”
Preventing neighboring RRAM cells from interfering with one another requires each cell to contain a selector made from a diode or transistor. Diode selectors have proved difficult to implement, therefore Wang and co-workers aimed to make RRAM stacks that were compatible with CMOS transistors.
To build the prototype RRAM cells, the researchers used three layers. They used physical vapor deposition to create a bottom electrode of nickel silicide or nickel germanosilicide, before adding a central dielectric switching layer of hafnium oxide, and a final top electrode of titanium nitride.
The researchers found that they could quickly and reliably switch the memory state of their cells, using very low operating currents. They suggest that the switching is enhanced by oxidation and reduction of nickel at the interfacial layer between the electrode and the dielectric. By providing more mobile oxygen species, these reactions might accelerate the formation and rupture of conductive filaments.
“Our electrodes can be easily formed on the source or drain terminal of a transistor,” says Wang. “In fact, our design effectively uses a CMOS transistor source or drain directly as the bottom electrode in a RRAM cell. This can lower the total cost and improve the scalability.”
In future, Wang and co-workers hope to shrink their nickel-based RRAM cells to a practical circuit scale to bring this promising technology into production.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Microelectronics
Wang, X. P., Fang, Z., Chen, Z. X., Kamath, A. R., Tang, L. J. et al. Ni-containing electrodes for compact integration of resistive random access memory with CMOS. IEEE Electron Device Letters 34, 508–510 (2013).
Laser process simulation available as app for first time
23.11.2015 | Fraunhofer-Institut für Lasertechnik ILT
Powering the next billion devices with Wi-Fi
19.11.2015 | University of Washington
The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...
Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.
In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...
In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.
Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...
Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...
AWI researchers’ unique 15-year observation series reveals how sensitive marine ecosystems in polar regions are to change
The warming of arctic waters in the wake of climate change is likely to produce radical changes in the marine habitats of the High North. This is indicated by...
25.11.2015 | Event News
17.11.2015 | Event News
21.10.2015 | Event News
25.11.2015 | Agricultural and Forestry Science
25.11.2015 | Earth Sciences
25.11.2015 | Physics and Astronomy