Earlier this week Infineon AG, a leading maker of semiconductors and the former owner of now bankrupt Qimonda memory maker, sued Elpida Memory for patent infringement. There are not a lot of details available at the moment, but there are at least three questions that arise. Let us try to answer them.
Infineon Has a Temper
Infineon claims that certain DRAM semiconductors and products of Elpida infringe four of Infineon's patents covering key inventions in semiconductor processing and device manufacturing. Although the claims are related to process technologies, Infineon claims that only certain devices include those techniques, hence, it is highly likely that the chips are made using the so-called buried wordline process tech, which is essentially an evolution of the deep trench fabrication technology, and which was used to be exclusive for Qimonda. At present, hardly anyone uses trench technology to manufacture DRAM at the processes below 90nm.
Infineon seems to still own certain patents that Elpida does not seem to have acquired. Historically, Elpida used stack process technology and started to marry upon the trench process technology back in 2008, when it announced the memorandum of understanding with Qimonda to develop the so called DRAM über-chip. The partnership was not an exacctly succesfule one.
Will Infineon Sue Other DRAM makers?
It looks like that only GDDR5 is made using buried wordline technology, hence, other DRAMs are probably unaffected because if they are, a lot of companies and products may be affected, including Sony PS3 that uses XDR, other game consoles that use GDDR3 as well as PCs that use DDR2 and DDR3 and that would cause a massive scandal.
As far as is known, deep trench is hardly used nowadays in general and for advanced GDDR5 chips in particular, so, it is hardly possible that Infineon will be able to sue Samsung, Hynix and other GDDR manufacturers for GDDR5 memory accusing it of infringing buried wordline-related patents. But perhaps Infineon wants to get back to making DRAM?
Infineon and Elpida did not comment on the news-story.