Analytical Model for Threshold Voltage of
Heteroª²Gate SOI MOSFET with Asymmetric Halo
Li Zunchao£¬Jiang Yaolin£¬Zhang Lili
£¨School of Electronics and Information Engineering£¬Xi'an¡¡Jiaotong¡¡University£¬Xi'an
710049£¬China£©
Abstract£ºA heteroª²gate SOI MOSFET structure with asymmetric halo doping is proposed to
improve the short channel effect and driving current£® The impurity with higher
concentration is injected into the channel end near the source and two materials with
different work function are put together to form the gate£® The analytical models of
surface potential and threshold voltage for the fully depleted device are constructed by
solving the 2D potential Poisson¡¯s equation£® It is shown that the proposed structure
can effectively suppress drain induced barrier lowering and hot carrier effect£¬ and the
threshold voltage clearly exhibits the considerable reverse short channel effect when the
channel length is less than 100 nm£® The two electric field peaks near the interface of
halo and gate materials will greatly increase the transfer speed of carriers passing
through the channel£® The derived analytical models accord with the result from twoª²dimension
device simulator MEDICI very well£®
Keywords£ºheteroª²gate£» threshold voltage£» surface potential