Les perspectives 2004 du march sc

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USING TCAD TO MINIMIZE PROCESS DISPERSIONS
G. DUBOIS D. ANDRADE
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• INTRODUCTION
• CALIBRATION RESULTS
• DIM PC PROCESS WINDOW SIMULATION RESULTS
• OTHER PROCESS CAUSES OF VARIATION
• COMBINED EFFECT OF PROCESS VARIATIONS
• CONCLUSION

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A - INTRODUCTION The goal is to demonstrate
that TCAD could be very useful in identifying the
process root causes of transistor electrical
parameters dispersion, mainly Ion , Vt and
Ioff.The following study was done on a 0.18µm
designed gate length CMOS process .
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DEVICES MENU
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• B - CALIBRATION
• PROCESS CALIBRATION
• Impurity diffusion, activation models and
  dislocation calibration variables were taken from
  INFINEON calibration work.
• ELECTRICAL CALIBRATION
• Mobility model has been shared with INFINEON
  simulation group.
• RESULTS
• I-V Characteristics end up very close to
  measurements performed on product.

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SOURCE
DRAIN
FET CHANNEL LENGTH
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Simulation properly matches product measurements.
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C PC DIM PROCESS WINDOW SIMULATION
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C PC DIM PROCESS WINDOW SIMULATION

• The simulation shows a good matching with  the
  real world .
• Halo implant tailoring allows to reduce the Ion
  (or Vt) spread,
• due to PC DIM variation, within /- 5 .

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D - ANALYSIS OF OTHER CAUSES OF
ELECTRICAL VARIATION

• 1 VARIATION OF EXTENSION IMPLANT DUE TO SCREEN
• OXIDE THICKNESS SPREAD.
• The extension implant being low energy, it is
  strongly influenced
• by screen oxide thickness variation

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REMAINING Gox SPACER 0 on Si
SPACER 0
POLY
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• TCAD simulation shows that
• A huge variation of remaining gate oxide induces
  a small
• variation of screen oxide.
• Screen oxide thickness variation represents 50
  of Spacer 0
• (poly oxidation thickness) variation.
• Consequently, the extension implant is not
  impacted
• by gate oxide, nor Spacer 0 fluctuations.

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• 2 VARIATION OF ANNEALS TEMPERATURE
• Rapid Thermal Process single wafer tools, using
  infra red heating systems, may present slight
  temperature variations inducing wafer to
• wafer, and within wafer, spread.

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E COMBINED EFFECTS OF PROCESS VARIATIONS
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F CONCLUSION
TCAD simulation consists in a very efficient
support for manufacturing engineers. It indeed
provides an accurate sizing of the different
processes effect. Only considering PC dim T
anneal variations induces 85 of the devices
electrical parameters total spread. Those two
components are the first order root causes of the
total device electrical variation.