Title :
Ultrathin gate oxide CMOS with nondoped selective epitaxial Si channel layer
Author :
Momose, Hisayo Sasaki ; Ohguro, Tatsuya ; Morifuji, Eiji ; Sugaya, Hiroyuki ; Nakamura, Shin-ichi ; Iwai, Hiroshi
Author_Institution :
Toshiba Corp., Yokohama, Japan
fDate :
6/1/2001 12:00:00 AM
Abstract :
The nondoped selective epitaxial Si channel technique has been applied to ultrathin gate oxide CMOS transistors. It was confirmed that drain current drive and transconductance are improved in the epitaxial channel MOSFETs with ultrathin gate oxides in the direct-tunneling regime. It was also found that the epitaxial Si channel noticeably reduces the direct-tunneling gate leakage current. The relation between channel impurity concentration and direct-tunneling gate leakage current was investigated in detail. It was confirmed that the lower leakage current in epitaxial channel devices was not completely explained by the lower impurity concentration in the channel. The results suggest that the improved leakage current in the epitaxial channel case is attributable to the improvement of some aspect of the oxide film quality, such as roughness or defect density, and that the improvement of the oxide film quality is essential for ultrathin gate oxide CMOS. AFM and 1/f noise results support that SiO2-Si interface quality in epitaxial Si channel MOSFETs is improved. Good performance and lower leakage current of TiN gate electrode CMOS was also demonstrated
Keywords :
1/f noise; CMOS integrated circuits; MOSFET; dielectric thin films; impurity distribution; leakage currents; semiconductor epitaxial layers; semiconductor-insulator boundaries; silicon; surface topography; tunnelling; 1/f noise; AFM; CMOS transistors; SiO2-Si; SiO2-Si interface quality; TiN; TiN gate electrode CMOS; channel impurity concentration; direct-tunneling gate leakage current; drain current drive; epitaxial channel MOSFETs; nondoped Si channel layer; oxide film quality; selective epitaxial Si channel layer; transconductance; ultrathin gate oxide CMOS; undoped Si channel; Electrodes; High-K gate dielectrics; Impurities; Large scale integration; Leakage current; MOSFETs; Silicon; Tin; Transconductance; Voltage;
Journal_Title :
Electron Devices, IEEE Transactions on