Folie 1

1
Proposals for PSP102 Model Improvements
3Q06 CMC Meeting
Date October 2006
Infineon
Joachim Assenmacher COM BTS TD DIF
CM Acknowledgement Jae-Eun Park, IBM
2
Outline

• Introduction of a Dielectric Constant Parameter
  in PSP103
• Implementation of Additional Instance Parameters
  in PSP103
• Improved Modeling Approach for Effective Doping
  in PSP103
• Conclusion and Summary

3
Introduction of a Dielectric Constant Parameter
in PSP103

• The TOX parameter in PSP is defined as the
  physical oxide thickness
• (QM-effect and poly depletion effect are
  separate).
• All electrical quantities in PSP are based on a
  fixed dielectric constant for SiO2 of 3.9
• (i.e. absolute permittivity of oxide eox
  e0eSiO2 is pinned to SiO2 in the model).
• In modern MOSFET devices medium-k dielectrics are
  common to reduce the gate leakage currents, at
  same drive capability (i.e. Cox).
• E.g. A nitrided oxide with a physical thickness
  of TOXr 2nm is related to an er of 4.8.
• Medium/high-k dielectric can be modeled as an
  equivalent oxide with thickness, adjusted for
  SiO2 (3.9) ? TOXEOT

• TOXEOT gives a correct scaling for
  charges/capacitances and current gain factor
  (i.e. set PSP TOX parameter to the calculated
  TOXEOT value Cox eox / TOX ).
• But TOXEOT gives a wrong scaling for gate
  tunneling currents, since above value is too low
  (for the tunneling distance) and have to be
  compensated with gate current parameter
  coefficients (unphysical). Gate currents have to
  scale always with the real physical oxide
  thickness (here TOXr of that oxinitride)!

4
Implementation of Additional Instance Parameters
in PSP103

• Implementation of additional instance parameters
  DELVTO (threshold voltage shift) and FACTU0
  (mobility multiplication factor) to handle
  further layout effects like well-proximity,
  stress-enablement, etc. (besides the intrinsic
  PSP STI-stress model).
• DELVTO and FACTU0 are common in BSIM4 netlists
  for commercial circuit simulators (e.g. HSPICE,
  Spectre, etc.).
• Even if an intrinsic well-proximity model will be
  available for PSP, DELVTO and FACTU0 would be
  beneficial in the future, for modeling of
  enhanced layout effects.
• Infineon can provide a verified Verilog-A PSP102
  model code, which supports DELVTO and FACTU0.

5
Improved Modeling Approach for Effective Doping
in PSP103
PSP102 Actual situation
PSP103 Proposal
FOL1, FOL2 RSCE of body effect
FOL1, FOL2 RSCE of body effect
NPCK, LPCK body effect
NPCK, LPCK body effect
NSUBO body effect
NSUBO body effect
NPCK, LPCK Vt-roll-up
Vbs
DPHIBL, DPHIBLEXP Vt-roll-up
DPHIBL, DPHIBLEXP Vt-adjustment
Vbs
DPHIBO Vth0-adjustment
NSUBO sets Vth0
DPHIBO Vth0-adjustment
NSUBO sets Vth0

• PSP102 Pocket doping NPCK and pocket length LPCK
  parameter have almost no influence on
  Vt-roll-up/off, only on body effect (unphysical).
  Threshold voltage will be mainly modeled by DPHIB
  parameters (offset voltage of FB).
• Proposal for PSP103 Pocket doping parameters
  NPCK and LPCK have an influence on Vt-roll-up/off
  and body effect as well (as they should be).
  DPHIB parameters can be used optional for
  Vt-adjustment.

6
Improved Modeling Approach for Effective Doping
(contd)
PSP103 Proposal for modified geometrical scaling
rule of effective doping
1
1
1 Introduction of one new local parameter NSUB
(Note In PSP102 Nsub is an internal variable)
7
Improved Modeling Approach for Effective Doping
(contd)
PSP103 Proposal for modified internal model
equation of FB (for Vt-adjustment)
Without FOL1 and FOL2 ! (Note PSP102 use
ln(NEFF/ni)
PSP102/103 Internal model equation of ?0 (for
body-effect) remains unchanged
With FOL1 and FOL2, i.e. RSCE of body-effect

• PSP103 Proposal
• FB- and ?0-equation share the same global
  parameters NSUBO, NPCK and LPCK by the
  NSUB-scaling rule (since also part of the
  NEFF-scaling rule).
• Additional reverse short channel effect
  parameters FOL1 and FOL2 will have an influence
  just on body effect (and will not decrease the Vt
  as in PSP102 and therefore mustnt be compensated
  by DPHIB parameters ).
  DPHIB parameters can be
  used optional for Vt-adjustment and fine-tuning.

8
Conclusion and Summary

• Introduction of a dielectric constant parameter
  in PSP103 will be needed for the correct and
  physical oxide thickness modeling of
  medium/high-k dielectrics, used in advanced CMOS
  technologies 1.
• Implementation of additional instance parameters
  DELVTO and FACTU0 in PSP103, will be needed for
  modeling of enhanced (extrinsic) layout effects
  2.
• A first suggestion for an improved modeling
  approach for the effective doping formulation
  (w.r.t. the influence of halo doping parameters
  on threshold voltage) in PSP103 has been made 3.
• For more information refer to Infineons PSP102
  evaluation report, 2Q06 CMC

1 BSIM4 also allows to specify a gate
dielectric constant (EPSROX) different from 3.9
(SiO2) for the modeling of medium/high-k
dielectrics. 2 Also part of BSIM4.
3 Simple approach, requires just one new local
parameter.