Scientists at Koninklijke Philips Electronics have developed a new technology for nonvolatile memory chips that, unlike flash memory, perform better the smaller the memory cells are made, the Dutch electronics giant announced earlier this week.
Philips said its new memory, based on a phase-change material, will match the speed, density, low voltage and low power consumption requirements of future silicon chips.
Phase-change materials, which change their physical state when heated, are used widely in DVD Rewritable discs. With rewritable DVDs, a laser is used to heat the material in order to switch it between phases and then to detect the change in its reflectivity.
In Philips' memory chip, a small voltage is sufficient to change the phase of the material between its two states; the changed state then remains even after the power is turned off, allowing the chip to retain the data.
Previous phase-change memories have suffered from the need for relatively high voltages to drive a current through the phase-change material and heat it, according to Philips. For silicon chips produced in advanced CMOS (complementary metal oxide semiconductor) process technologies, these voltages are not practical, Philips said.
To overcome this problem, the Dutch company developed a new phase-change material made of antimony and tellurium. The material enables switching between the two phases -- amorphous and crystalline -- to occur at a low electric field strength of around 14V per micron.
As chip makers move to smaller manufacturing processes, from the current 130 nanometer and 90 nm technologies to 50 nm, the voltage required by phase-change memories becomes an issue -- but Philips said a strip of its new phase-change material 50 nm long requires a voltage of just 0.7V to change its state.
In addition, the new material changes phase between 100 and 200 times faster than the time required to program a flash memory cell, according to Philips.
As such, the new phase-change memory could be an attractive alternative to DRAM (dynamic random access memory) for certain applications, the company said. DRAM, a different kind of memory which is found in most PCs, doesn't store data when power is switched off.