Yale University, SRC develop next-generation DRAM

RESEARCH TRIANGLE PARK, USA: Semiconductor Research Corp. (SRC), the world's leading university-research consortium for semiconductors and related technologies, and Yale University researchers today announced they have developed a new DRAM cell using ferroelectric layers that could significantly increase the technological and market competitiveness for DRAM technology.

According to early findings, researchers have found a way to apply ferroelectric material to a DRAM cell, which eliminates the need for a storage capacitor found in conventional DRAM. Ferroelectric DRAM (FeDRAM) is a capacitor-less DRAM cell, with a cell structure very similar to a CMOS transistor, except that the gate dielectric is ferroelectric.

Compared to the conventional DRAM cell, FeDRAM offers simpler cell structure, improved scalability, a smaller cell size, orders of magnitude longer retention time, lower power consumption and the possibility of storing multi-bits per cell. Storing many bits of information in a single DRAM cell has not been done and is found primarily only in flash memories.

“There have been numerous research groups that have worked on similar ferroelectric device structures for non-volatile memory applications, but we believe this is the first innovative FeDRAM solution to an industry-wide problem,” said Professor T.P. Ma, Raymond John Wean Professor of Electrical Engineering at Yale University.

“If we are able to show through further research that FeDRAM indeed possesses the superb properties that we are seeing now, these advancements would produce meaningful cost and performance benefits to global DRAM makers and their customers.”

Reducing costs, increasing competitiveness
According to Professor Ma, the FeDRAM structure provides many benefits. FeDRAM allows a device to be programmed and erased by a gate voltage pulse. Since charge retention is at least 1,000 times longer than that in conventional DRAM, refreshing can be much less frequent.

Its circuit architecture is similar to flash memory, helping the manufacturability of the technology. The ability to use proven and existing fabrication facilities and equipment would make an industry transition to FeDRAM much easier.

“One key advantage of FeDRAM is its ability to scale,” said Kwok Ng, Director of Device Sciences at SRC. “Existing DRAM technology is not highly scalable due to its difficulty in maintaining an acceptable storage capacitance while reducing footprint. However, we see the potential for greater scalability with FeDRAM, extending the benefits well into the future.”

Researchers now are working toward being able to demonstrate FeDRAM cells, simple building block circuits and pathways for scaling. They believe that with SRC support and collaboration with other SRC member companies, FeDRAM will be ready to transfer to the industry for production in the foreseeable future.