Spansion, the US memory-chip maker, on Tuesday filed for bankruptcy protection for its unit in Japan as it sought to restructure in the face of a sharp slowdown in demand that is affecting all parts of the semiconductor industry.

California-based Spansion, part-owned by Japan’s Fujitsu and Advanced Micro Devices of the US, is the biggest producer of Nor flash memory chips – a technology that has been losing ground to Nand memory chips, which store data faster.