OTHER LONG-TERM LIABILITIES (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Other Long-term Liabilities [Abstract]
Other long-term liabilities	$ 6,454	$ 4,186
Subsidies to Stress Free Polishing Project, Commenced in 2008 and 2017 [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	1,126	1,251
Subsidies to Electro Copper Plating Project, Commenced in 2014 [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	2,188	2,666
Subsidies to Polytetrafluoroethylene, Commenced in 2018 [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	125	135
Subsidies to Tahoe-Single Bench Clean, Commenced in 2020 [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	1,962	0
Subsidies to Backside Clean-YMTC National Project, Commenced in 2020
Other Long-term Liabilities [Abstract]
Other long-term liabilities	751	0
Other [Member]
Other Long-term Liabilities [Abstract]
Other long-term liabilities	$ 302	$ 134