March 2010

Fast Memory Erase, LLC v. Spansion, Inc., 2010 WL 363498.

Fast Memory Erase, LLC filed a patent infringement suit against Spansion, Inc., Intel Corportion, Numonyx, Inc., Stmicroelectronics, Inc., Nokia Corporation, Sony Ericsson Mobile Communications, Motoral, Inc., and Apple, Inc. The suit, filed on June 9, 2008, alleged infringement of claims 1 and 16 of U.S. Patent No. 6,236,608 (the ‘608 patent) and claim 1 of U.S. Patent No. 6,303,959 (the ‘959 patent). These patents cover a method for erasing memory cells in a semiconductor device. The court only considered the claim under the ‘959 patent; claims 1 and 16 of the ‘608 patent are being re-examined by the U.S. Patent and Trademark Office.

The ‘959 patent reduces sources leakage, which occurs when the memory of a semiconductor device is erased. Fast Memory claims that the patent is “most effective in erasing non-volatile flash memory devices.” The issue is whether the patent is limited to one specific method of erasing flash memory, source erase, or whether it is applicable to other procedures, such as channel erase, gate erase, and drain erase. Defendants argue that the patent’s specification limits it to source erase. Fast Memory argues that the specification language “source leakage” refers to a reduction of source leakage in all procedures: “an unwanted and slow escape or entrance of particles or material to ground or other parts.”

The patent specification only discussed source leakage in reference to source erase, and the “claims of a patent cannot be of broader scope than the invention that is set forth in the specification.” While Fast Memory pointed out no language in the specification that applied the patent to other erase procedures, Defendants cited more than six statements “in the specification describing the invention as limiting leakage during source erase.”

The court found that the specification itself limited “source leakage” to source erase. Since “a person of ordinary skill in the art would clearly understand that the invention refers to source erase, not to other type of erase procedures,” the court construed “source leakage” as “leakage from the source terminal to the substrate terminal that occurs during source erase.”