At present, the United States chooses the mature process of 28nm（nanometer） as a new position to restrain the development of China's semiconductor industry.

The U.S. Department of Commerce has tightened the power of examination and approval, forbidding U.S. companies to directly export equipment related to this process to China. At the same time, without U.S. license, any company using technology related to this process is prohibited from transferring relevant equipment from a third party to enter the Chinese market.

China Taiwan wafer maker TSMC（Taiwan Semiconductor Manufacturing Company） and UMC（United Microelectronics Corporation）expanded the capacity of 28nm process in mainland China, and did not receive the US supply license. In addition, the wafer manufacturers in Taiwan factories would have to obtain the US permission to transfer the US equipment to the Chinese mainland, although the US did not explicitly prohibit them, but this is the result of the application.

28nm process technology is regarded as the dividing line between advanced semiconductor process and mature semiconductor process, and its products are widely used in new energy vehicles, autonomous driving, home appliances, communications and other fields. it is particularly noteworthy that in the field of autonomous driving, most Chinese AI participants use chips of this process. Among China's new energy vehicle manufacturers, the chips of intelligent cockpit and automatic driving of most brands will also be upgraded to 28nm process. In other words, 28nm process technology is also the watershed of China's automobile intelligence.

In the field of semiconductor manufacturing, the most mature level of Chinese semiconductor manufacturers is 28nm, with SMIC international （Semiconductor Manufacturing International Corporation）and Shanghai Huahong(Shanghai Huahong Group Co., Ltd.) as pioneers. China Restricted by the US technology level, 28 nm semiconductor has a self-sufficiency rate of less than 20%. Before the self reliant ideal was achieved, TSMC and UMC factory in China continued to support the core technology of China's semiconductor industry.

In fact, the suppression of Chinese semiconductors by the United States is for the enterprises on the list of prohibited entities. Influenced by geopolitical game, TSMC and UMC are very cautious in expanding the Chinese mainland, and are producing technology for 28 nm processes within the US safety red line. In this way, 28nm has become the highest tolerance value of the United States for the development of China's semiconductor technology. In practical operation, the United States has not relaxed its control on China's semiconductor.