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Aug 06

Crossbar

Emerging from stealth mode, Crossbar today has given the first details of its ReRAM technology. Their website has been updated with a fair amount of information including a rather neat TEM video by Chief Scientist and Co-Founder Prof. Wei Lu of the University of Michigan, Ann Arbor.

Some of the highlights are:

As one might expect based on the company name, Crossbar’s ReRAM technology is based on a BEOL stackabe crossbar which can be fabricated above conventional CMOS. The technology is presented as a NAND replacement with 1TB of storage being envisioned on a 200mm2 die. In a white paper, by Hagop Nazarian, Vice President of Engineering and Co-Founder, the switching mechanism appears filamentary in nature and is described as “In a switching media, nanoparticles form a conduction path between the top and bottom electrodes”. The white paper also contains an introduction going into to the limitations of conventional NAND technology. Like myself, Hagop is a Spansion alumnus and he certainly is an expert in Flash and its issues. Other advantages of Crossbar’s approach are outlined in the paper (and News announcement) and include a 20x lower programming power and superior scalability, retention and endurance. The graph below is an IV characteristic of a 50nm by 50nm cell.

As one (I) might not expect, the switching layer is amorphous silicon with the cell structure is described as being a non-metallic bottom electrode with an amorphous silicon switching medium and a metallic top electrode. With a caveat relating to the nature of the bottom electrode, the use of standard CMOS materials will help with process technology development and achieving acceptable manufacturability.

Watch this space!

Christie Marrian, ReRAM-Forum moderator

2 comments

  1. admin

    More details on Crossbar’s cell structure. As per ‘briefing materials from Crossbar’ tthe call comprises of a Silver top electrode over amorphous silicon over polysilicon. Crossbar’ have fabricated 1Mbit arays using 110 nm technology. http://www.eetimes.com/document.asp?piddl_msgorder=thrd&doc_id=1319139&page_number=1

  2. Peter Newman

    Thanks as ever for keeping us up to date, Christie!

    I have no doubt Crossbar will concentrate on the big existing markets for digital storage first but many are saying the next wave of computing will be “cognitive”. So it is notable that Wei Lu has long had research interests in neuromorphic systems which can use of the analog storage capabilities of ReRAM.

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