1. State Key Lab of Fabrication Technologies for Integrated Circuits, Institute of Microelectronics, Chinese Academy of Sciences, No. 3 West Road, Beitucheng, Beijing 100029, China
2. Laboratory of Microelectronic Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, No. 3 West Road, Beitucheng, Beijing 100029, China
3. University of Chinese Academy of Sciences, 19 Yuquan Road, Shijingshan District, Beijing 100049, China
4. SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, P. O. Box 912, Beijing 100083, China