A drain current model for the full depletion cylindrical gate metal-oxide-semiconductor field-effect transistor(MOSFET)is proposed to address the issue that free carrier has a significant impact on surface potential when deep submicron MOSFET is in the accumulation or inversion region. Accounting for the effects of depletion charge and free carrier
the potential Poisson's equation is solved using the gradual channel approximation to get the analytical model of surface potential which is valid from the accumulation region to depletion region
and to inversion region. The continuous current model from linear region to saturation of cylindrical gate MOSFET is obtained from the surface potentials of source and drain.The surface potential and current model are verified by the device simulation software Sentaurus. The results show that the surface potentials in the accumulation and strong inversion regions tend to be saturated respectively
while the surface potentials in the depletion and weak inversion regions increase as the gate voltage increases. As the drain voltage increases
the channel is pinched-off which leads to the invariability of surface potential. The increase of channel doping density causes both rising the negative bias voltage needed by flat voltage and increasing the surface potential. Comparisons with the threshold-based models show that the precision of the proposed analytical model improves by more than 16%.
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YANG B, BUDDHARAJU K D, TEO S H, et al. Vertical silicon-nanowire formation and gate-all-around MOSFET [J].IEEE Electron Devices Letters, 2008, 29(7):791-794.
LIU Feng, HE Jin, ZHANG Lining, et al. A charge-based model for long-channel cylindrical surrounding-gate MOSFETs from intrinsic channel to heavily doped body[J]. IEEE Transactions on Electron Devices, 2008, 55(8):2187-2194.
CHO H J, PLUMMER J D. Modeling of surrounding gate MOSFETs with bulk trap states [J]. IEEE Transactions on Electron Devices, 2007, 54(1):166-169.
YU Bo, LU Wenyuan, LU Huaxin, et al. Analytic charge model for surrounding-gate MOSFETs[J]. IEEE Transactions on Electron Devices, 2007, 54(3):492-496.
GILDENBLAT G, WANG Hailing, CHEN Ten-Lon,et al. SP: an advanced surface-potential-based compact MOSFET model[J]. IEEE Solid-State Circuits, 2004, 39(9):1394-1406.
CHEN Tsung-Hao, TSAI J L, KARNIK T,et al. HiSIM: hierarchical interconnect-centric circuit simulator [C]∥Proceedings of IEEE/ACM International Conference on Computer-Aided Design. New York, USA: ACM, 2004:489-496.
VAN LANGEVELDE R, GILDENBLAT G. An advanced surface-potential-based MOSFET model [M]. Berlin, Germany: Springer, 2006:29-66.
HE Jin, ZHANG Jian, ZHANG Lining, et al. A surface potential-based non-charge-sheet core model for undoped surrounding-gate MOSFETs [J/OL]. Journal of Semiconductors, 2009, 30(2):024001-4. [2009-11-19]. http:∥www.jos.ac.cn/new_cn/ch/common/view_abstact.aspx?file_no=08052002flag=1.
JIMENEZ D, SUNE J, MARSAL L F, et al. Continuous analytic I-V model for surrounding-gate MOSFETs [J]. IEEE Electron Devices Letters, 2004,25(8):571-573.
TSIVIDIS Y P. Operation and modeling of the MOS transistor[M]. New York, USA: McGraw-Hill, 1999:131-140.
DONALD A N. Semiconductor physics and devices basic principles [M]. New York, USA: McGraw-Hill, 2003:351-420.