SINGAPORE: China has begun mass producing domestically developed immersion deep-ultraviolet (DUV) lithography machines, a technology crucial to advanced chipmaking, a person familiar with the matter said, marking a key step forward in Beijing's drive to reduce its reliance on foreign technologies. Shanghai Aishengna Electronic Technology Group, a little-known Chinese state-owned company, is leading the production effort after incorporating teams from top Chinese lithography startups, the source said, declining to be named due to the sensitivity of the subject. DUV is a key chipmaking tool long dominated by ASML. Aishengna's DUV machine is expected to require further testing and remains far from matching the Dutch firm's competing models, the source said. Successful deployment would, however, give Chinese chipmakers an alternative source of equipment if Western governments further restrict exports or servicing of foreign lithography tools.