Resistive RAM – A New Approach

Resistive random-access memory (RRAM) is widely hailed as the “most likely to succeed” in the race to develop a new, more scalable, high capacity, high performance and reliable memory.

A typical RRAM cell has a switching material with different resistance characteristics sandwiched by two metallic electrodes. The switching effect of RRAM is based on the motion of ions under the influence of an electric field or heat and the switching material’s ability to store the ion distribution, which in turn causes a measurable change of the device resistance.

Compared to traditional Flash memory, RRAM is faster, bit-alterable and requires lower voltage, enabling its use in both embedded and SSD applications. The simple RRAM cell structure offers best area efficiency (4F2 cell), excellent scalability and 3D integration potential (both 3D stacking and vertical cell). RRAM requires lower programming currents than PCM or MRAM with comparable performance in terms of retention and endurance.

There are different approaches to implementing RRAM, based on different switching materials and memory cell organization. Those variables drive significant performance among the different materials being used.

RRAM has already been the subject of intense research and development, with several companies claiming to have prototype memory chips available in the next 1-2 years.

One of the biggest challenges for RRAM technology has been the integration of the RRAM array with standard CMOS technology and standard manufacturing processes. Crossbar RRAM technology has proven its manufacturability with a working array produced in a commercial fab. This working silicon is a fully integrated monolithic CMOS controller and memory array chip. The company is currently completing the characterization and optimization of this device and plans to bring its first product to market in the embedded SOC market.