The device is based upon the super-halo discussion by Taur et al. . Reasonable device geometries can be designed for simulations in the deep sub-100-nm regime. The n+ polysilicon gate has a doping of 2e20 cm-3 and a height of 60 nm. The physical tox is 20 Angstroms. Leff (as defined between where the source/drain dopings fall to 2e19 cm-3) was extracted and found to be 50 nm. Lpoly was arbitrarily set at 85 nm. Because the device is symmetric, the origin for the lateral grid is at the middle of the channel (x = 0); the interface between the gate oxide and bulk is chosen as the depthwise origin (y = 0). In the simulations, only the portion of the MOSFET up to the source/drain regions for a lateral distance, Lsd = 57.5 nm, from the edge of the gate to model boundary, is used. The source and drain contacts are one-node-thick electrodes on the left and right boundaries of the silicon extending down a depth of 10 nm from the depthwise origin. The particular electrode to silicon contact resistances for this model were assumed to be zero.
A full 2-D doping profile (placed in the doping directory) was developed. The
file sh50.doping contains a 2-D profile represented as three columns: the
first is lateral position, x; the second is depth position, y; the third is
the cumulative doping of the source/drain region and super-halo at those
points, Nd(x,y) - Na(x,y). There is a separate background uniform p-type
doping of 1e15 cm-3. The profile is simply generated from an analytic
formula, as in sh50.analytic, that describes two 2-D gaussian functions: one
for the n+ source/drain, one for the p+ halo. The device profile is mirror
symmetric about x = 0.
A set of simulated Id vs. Vgs curves (PREVIEW) are stored in the idvg
directory. The characteristics have been generated using the Drift-Diffusion
(DD) model as described in MEDICI  and taking into consideration poly-
depletion (PD) and quantum mechanical (QM) effects. A sample MEDICI file
inputfile50 is included for reference. The I-V characteristics are text files
labeled according to their drain bias (where Vbs = 0 V); for example, ddd0.1
has a Vds of 0.1 V. Each file has two columns of data: the first is Vgs in
0.1 V steps and the second is normalized Id (A/µm).
This device was scaled down to a 35 nm and up to a 65 nm Leff by shifting the
gaussian center in the x-direction of both the source/drain and halo dopings
simultaneously. Simulated values of threshold voltage (defined as Vg where
Id = 1e-6 A/µm and Vd = 1.2 V) and DIBL are plotted as a function of Leff in
the following GRAPH.
 Y. Taur et al., IEDM proceedings, p. 215, 1997
 MEDICI manual, Technology Modeling Associates