TY - GEN
T1 - Investigation on the work function of tungsten and thermal stability of W/SiO2/Si, W/SiON/Si and W/HfO2/Si gate stacks
AU - Jiang, Pei Chuen
AU - Chen, Jen Sue
AU - Cheng, K. H.
AU - Hu, T. J.
AU - Huang, K. B.
AU - Lee, F. S.
PY - 2006
Y1 - 2006
N2 - Replacement of poly-Si and SiO2 with new gate electrode and high k gate oxide is an inevitable trend for next-generation CMOS integrated circuits. Therefore, work function (Φm) of gate electrodes as well as the thermal stability and electrical behaviors of MOS capacitors should be understood. In this study, tungsten (W) is applied as the gate electrode and the gate dielectric materials are SiO2, SiON and HfO2. Φ of W and electrical properties of the MOS structures are investigated. Φm,measured of W is calculated from the flat-band voltage (V m,measured) of MOS capacitors with dielectrics of various thicknesse. For W/SiO2/Si structure, the Φm,measured of W is 4.67 V; however, the Φm,measured of W in W/SiON/Si and W/HfO 2/Si structures is 4.60 V and 4.84 V, respectively. The result means that the Φm,measured of W in W/HfO2/Si structures has extrinsic contributions to Fermi level pinning. The phase of as-deposited W is β-W (or β-W+α-W) phase and transfers to α-W+WO3 mix phase after annealing at 500°C in N2+H2 ambient for 30 min. The trapped charges and oxide charges of dielectric are reduced after annealing. However, the EOT of W/SiO2/Si increases significantly after annealing, indicating the thermal stability of this capacitor is poor.
AB - Replacement of poly-Si and SiO2 with new gate electrode and high k gate oxide is an inevitable trend for next-generation CMOS integrated circuits. Therefore, work function (Φm) of gate electrodes as well as the thermal stability and electrical behaviors of MOS capacitors should be understood. In this study, tungsten (W) is applied as the gate electrode and the gate dielectric materials are SiO2, SiON and HfO2. Φ of W and electrical properties of the MOS structures are investigated. Φm,measured of W is calculated from the flat-band voltage (V m,measured) of MOS capacitors with dielectrics of various thicknesse. For W/SiO2/Si structure, the Φm,measured of W is 4.67 V; however, the Φm,measured of W in W/SiON/Si and W/HfO 2/Si structures is 4.60 V and 4.84 V, respectively. The result means that the Φm,measured of W in W/HfO2/Si structures has extrinsic contributions to Fermi level pinning. The phase of as-deposited W is β-W (or β-W+α-W) phase and transfers to α-W+WO3 mix phase after annealing at 500°C in N2+H2 ambient for 30 min. The trapped charges and oxide charges of dielectric are reduced after annealing. However, the EOT of W/SiO2/Si increases significantly after annealing, indicating the thermal stability of this capacitor is poor.
UR - https://www.scopus.com/pages/publications/33947629120
UR - https://www.scopus.com/pages/publications/33947629120#tab=citedBy
U2 - 10.1557/proc-0917-e12-01
DO - 10.1557/proc-0917-e12-01
M3 - Conference contribution
AN - SCOPUS:33947629120
SN - 1558998748
SN - 9781558998742
T3 - Materials Research Society Symposium Proceedings
SP - 167
EP - 173
BT - Gate Stack Scaling
PB - Materials Research Society
T2 - 2006 MRS Spring Meeting
Y2 - 17 April 2006 through 21 April 2006
ER -