suppression of random dopant-induced threshold voltage fluctuations in sub-0.1μm mosfet’s with...
DESCRIPTION
Outline Introduction MOSFET design to suppress the RDFs Summary Bulk MOSFET and its scaling challenges Random Dopant Fluctuations (RDFs) MOSFET design to suppress the RDFs Adjusting the channel doping profile SummaryTRANSCRIPT
Suppression of Random Dopant-Induced Threshold Voltage
Fluctuations in Sub-0.1m MOSFETs with Epitaxial and -Doped Channels
A. Asenov and S. Saini, IEEE Trans. on Electron Devices, Aug 1999
Changhwan Shin Department of Electrical Engineering and Computer
Sciences University of California, Berkeley, CA 94720 March 2, 2009
Outline Introduction MOSFET design to suppress the RDFs
Summary
Bulk MOSFET and its scaling challenges Random Dopant Fluctuations
(RDFs) MOSFET design to suppress the RDFs Adjusting the channel
doping profile Summary Outline Introduction MOSFET design to
suppress the RDFs Summary
Bulk MOSFET and its scaling challenges Random Dopant Fluctuations
(RDFs) MOSFET design to suppress the RDFs Adjusting the channel
doping profile Summary 3 Bulk-Si MOSFET Scaling Challenges
Lg Leakage drain current reduce Tox,eq and Xj gate current use
high-k gate dielectric Tox Substrate Gate Source Drain XJ Leff Nsub
Incommensurate gains in ION with scaling limited carrier mobilities
strain Si to enhance meff parasitic resistance use metallic
(silicide) source/drain extensions Performance variation Sources of
Variability
Sub-wavelength lithography: Resolution enhancement techniques are
costly and increase process sensitivity Statistical dopant
fluctuations Atomistic effects become significant in nanoscale FETs
SiO2 Gate Source Drain A. Brown et al., IEEE Trans. Nanotechnology,
p. 195, 2002 A. Asenov, Symp. VLSI Tech. Dig., p. 86, 2007 Outline
Introduction MOSFET design to suppress the RDFs Summary
Bulk MOSFET and its scaling challenges Random Dopant Fluctuations
(RDFs) MOSFET design to suppress the RDFs Adjusting the channel
doping profile Summary 6 Random Dopant Fluctuations (RDFs)
Intrinsic variation in MOSFET parameters Arising from the small
number of discrete dopants and their random position in the channel
depletion regions SiO2 Gate Source Drain A. Brown et al., IEEE
Trans. Nanotechnology, p. 195, 2002 7 Outline Introduction MOSFET
design to suppress the RDFs Summary
Bulk MOSFET and its scaling challenges Random Dopant Fluctuations
(RDFs) MOSFET design to suppress the RDFs Adjusting the channel
doping profile Summary 8 MOSFET designs to suppress RDFs
Radical solutions Un-doped channel MOSFET (UTB, FinFET, DG,
gate-all-around) More demanding of technological modification
Fluctuation-resistant architectures viaappropriate tailoring of the
channel doping profile Thin, low doped layer in the channel
Conventional Epitaxial Epitaxial w/ -doping 9 3D atomistic
simulation results
Epitaxial MOSFET Vt is evaluated via 3D atomistic simulator Results
Vt dramatically reduced for the first 10nm of epilayer Maximum depi
should be considered with Tox, Xj, Leff Leff/depi > 5 Boron
diffusion into epi-layer; tolerable up to 1017cm-3 Dependence of Vt
on the back-doping; Screening effect The holes in the heavily doped
region screen the charge of the discrete random acceptors in the
thin depletion layer 10 3D atomistic simulation results
Epitaxial MOSFET with the delta doping Results If the -doping is
only partially depleted (i.e. depi is deep enough, or screen effect
is valid), the doping concentration NAb increase will result in Vt
reduction. Additional degree of freedom in tailoring the threshold
voltage Epitaxial Conventional Epitaxial w/ -doping 11 Outline
Introduction MOSFET design to suppress the RDFs Summary
Bulk MOSFET and its scaling challenges Random Dopant Fluctuations
(RDFs) MOSFET design to suppress the RDFs Adjusting the channel
doping profile Summary 12 Summary Fundamental issue; RDFs in deep
sub-micron MOSFET
3D statistical atomistic simulations to study RDFs Random
dopant-induced threshold voltage fluctuationscan be significantly
suppressed in MOSFETs with low- doped epitaxial channels. 13 Q
& A Thank you for your attention!!! Questions?