Hitachi GST SVP takes a punt on STT-RAM

The general manager and VP of Engineering at Hitachi GST has left to join a NAND and DRAM replacement technology company, Grandis. That seems like a risky move.

Said GM and VP Mohamad Krounbi is joining Grandis to be its SVP for engineering, taking on responsibility for "all STT-RAM technology and product development at Grandis and for ensuring that the company's licensees incorporate the best technology and processes as they bring their STT-RAM products to market."

What is STT-RAM? It is Spin Transfer Torque Random Access Memory (or magneto-resistive random access memory - MRAM) and is positioned as a technology that can move down to smaller process sizes than NAND, and combine its non-volatility with the speed of DRAM. The idea is to have a spin-polarised current in a tunnel magneto resistance element. Normally an electric current is not polarised as half its electrons are classed as spin-up and half as spin-down. This can be changed by passing a current through a thick magnetic layer such that it has more spin-up electrons than spin-down or vice-versa.

The next step is to have this spin-polarised current transfer its spin characteristic to a magnetic element from which the direction of magnetism signifies a binary one or zero.

Hynix was making approving noises about STT-RAM, as a NAND flash successor, in 2008. It signed an STT-RAM license agreement with Grandis in April of that year.

At that time Sung Wook Park, Head of the R&D Division at Hynix, said: “Grandis is leading in STT-RAM technology and has a broad portfolio of fundamental patents in this area. Through this partnership with Grandis, we look forward to integrating leading-edge STT-RAM technology into our semiconductor manufacturing processes and to a new era in memory capability at advanced technology nodes.”

Researchers at Hitachi and Tohoyu University demonstrated a 32Mbit STT-RAM device, which they called an SPRAM device, in 2009. The two have developed a 2-bit multi-level cell version of the technology. Hitachi has a roadmap to develop a 1Gbit chip by 2015.

Renesas of Japan, a company formed by Hitachi and Mitsubishi spinning off their chip businesses, is developing STT-RAM product, apparently using licensed technology from Grandis.

Fujitsu also has an internal STT-RAM development effort.

We could position STT-RAM as a candidate, along with Phase-Change Memory and HP's Memristor, for the NAND follow-on technology. The STT-RAM technology area looks solid and Grandis appears to be a key player, making Krounbi's move much less of a gamble than it first appears. ®