Effects of dopant granularity on superhalo-channel MOSFETs according to two- and three-dimensional computer simulations |
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Authors: | Voon-Yew Aaron Thean Sadd M White BE Jr |
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Affiliation: | Adv. Process R&D Lab., Motorola Inc., Austin, TX, USA; |
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Abstract: | We have performed two-dimensional (2-D) and three-dimensional (3-D) computer simulations of random dopant fluctuations in 25-nm planar n-channel metal-oxide-semiconductor field effect transistor (MOSFET) with superhalo channel doping. Our study shows that 2-D simulations that neglect lateral percolation of the carriers can overestimate the impact on threshold voltage (V/sub T/) fluctuations by as much as a factor of four. Fundamental differences in the way the 2-D and 3-D models describe subthreshold and near-threshold conduction are highlighted in our study. Our models reveal that surface percolation of carriers is an effective agent for reducing V/sub T/ fluctuations. In addition, the halo only enhances the V/sub T/ fluctuations by approximately 10%. Though the influence of the superhalo in the device may be overwhelmed by atomistic granularity according to the 2-D model, 3-D simulations show that the halo continues to function coherently for the MOSFET ensemble when charge percolation is accounted. |
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