Random Discrete Dopant Fluctuated Sub-32 nm FinFET Devices
Y. Li, C-H Hwang, S-M Yu, H-M Huang and H-M Chen
National Chaio Tung University, TW
effect of random dopant, fluctuation of electrical characteristics, sub-32 nm, planar MOSFET, bulk FinFET
Scaling of silicon production technology has approached the sub-65nm regime. Device’s electrical characteristics fluctuate according to the discreteness and randomness of dopants in sub-32nm technologies. In this paper, we investigate the random-dopant-induced electrical characteristics fluctuations, fluctuations of the on-state current, the off-state current, the threshold voltage, the drain-induced barrier height lowering, and the subthreshold swing, in sub-32 nm planar MOSFET and bulk FinFET devices. A large-scale computational statistical approach is performed, in a sense of discrete atomic dopants, with three-dimensional density-gradient device simulation. The validation of simulation technique is firstly calibrated with sub-65 nm silicon measured data. The fluctuations of device performance are dominated not only by the number but by the position of random dopants in both the planar MOSFET and bulk FinFET devices. Our result implies that even device has the same on-state current; the inhomogeneity of the potential that induced by the discreteness of the channel dopants strongly disturbs the carrier’s conducting path at subthreshold region, and thus results in different off-state current. For the devices with the same threshold voltage, the 32-nm bulk FinFET possesses excellent immunity against the discreteness and randomness of dopants, compared with the aforementioned fluctuations of the planar MOSFET. The superiority of the suppression of the fluctuation (more than 50% reduction of fluctuation) is mainly due to improved gate controllability in bulk FinFET devices.
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