China's leading flash memory chipmaker, YMTC, has published nearly 20 new patents for processes that can improve computing efficiency and optimize chip-stacking structures. The patents, which were published in late March, include an improved stacking structure, a method to shield from electromagnetic interference, and a method to boost storage density. Some of the innovations involve software optimization, such as a method to refresh data in flash memory. The disclosure comes as China aims to build up its semiconductor self-sufficiency amid US technology restrictions.