China's Yangtze River Storage Technology (YMTC) has started building a 3D NAND flash plant.

YMTC, through its ownership of contract chip manufacturer XMC, has started building a memory semiconductor fab on a 13-hectare site at the Donghu New Technology Development Zone in Wuhan. Tsinghua Unigroup, which owns 51.04 per cent of YMTC, said the fab would soak up $24bn in investment. The other 48.96 per cent of YMTC is owned by China's National Integrated Circuit Industry Investment Fund, the Hubei IC Industry Investment Fund, and the Hubei Science and Technology Investment Group.

This will be the largest memory plant in China and include three 3D NAND production lines. Volume production should start in 2018, with a run rate of 300,000 12-inch wafers a month by 2020. News about the project arrived in April last year.

Building 3D NAND chips is the leading edge flash technology. IMTF, Samsung, Toshiba and WDC are all building 64-layer chips while SK Hynix, with 48-layer chips in production, is developing a 72-layer design. First chips could flow in the second half of this year.

We might expect YMTC to start with fewer layers to simplify the development of its technology. It is not known what architecture its 3D NAND design will use. Intel and Micron have a floating gate design while Samsung, SK Hynix, Toshiba and WDC use charge-trap technology.

YMTC chairman Zhao Weiguo also heads up Tsinghua Unigroup, which tried to invest $3.8bn in Western Digital last year through its Unisplendour subsidiary. The attempt was stopped by the US government. Previously Tsingua Unigroup had also tried, and failed, to buy Micron.

Interestingly, back in November YMTC issued a statement saying: "Up to now, YMTC has never held negotiations with Micron Technology on any topic. Mr Ding Wenwu, vice chairman of YMTC, has never made any comment or released any information on this."

"Up to now" indeed. ®