Investigation of Channel Doping Concentration and Reverse Boron Penetration on P-Type Pi-Gate Poly-Si Junctionless Accumulation Mode FETs

• Published in: IEEE journal of the Electron Devices Society 2018-01, Vol.6, p.314-319
• Main Authors: Hsieh, Dong-Ru, Chan, Yi-De, Kuo, Po-Yi, Chao, Tien-Sheng
• Format: Article
• Language: English
• Subjects: 3-D integrated circuits (ICs); Accumulation; Activation; Boron; Carrier density; channel doping concentration; Doping; Fabrication; Field effect transistors; Ions; junctionless accumulation mode (JAM); Logic gates; Penetration; Pi-gate (PG); poly-Si; reverse boron penetration; Threshold voltage
• ISSN: 2168-6734; 2168-6734
• DOI: 10.1109/JEDS.2018.2803800

In this paper, the influence of channel doping concentration and reverse boron penetration on p-type Pi-gate (PG) poly-Si junctionless accumulation mode (JAM) FETs has been experimentally investigated and discussed. Effective carrier concentration (N eff ) and threshold voltage (V TH ) are found to be sensitive to doping concentration. Moreover, the positive shift in V TH and the degradation in the subthreshold behavior for PG JAM FETs are observed after an additional source/drain (S/D) activation process. Using a low thermal-budget S/D activation process, PG JAM FETs with a suitable channel doping concentration can show excellent electrical characteristics: 1) steep subthreshold swing of 86 mV/dec.; 2) low average subthreshold swing (A.S.S.) of 96 mV/dec.; and 3) high ON/OFF current ratio (I ON /I OFF ) of 7.7 × 10 7 (I ON at V G - V TH = -2 V and V D = -1 V).