Samsung Electronics Co., the world\'s top memory chip supplier, said Thursday it had started to mass-produce memory chips based on 20-nanometer class technology in a move to cement its leadership and weather an industry-wide downturn. The company also started operation of its 16th production line south of Seoul, which it claims is the world\'s largest memory production facility. The new plant will manufacture NAND flash memory devices, it said. Global dynamic random access memory (DRAM) makers in Taiwan and Japan are producing memory chips based on 30 or 40-nanometer technology. The finer the technology, the cheaper and more cost-effective it is to mass-produce memory chips, which in turn results in better margins.