Investigation of StrainTemperature Stress on Rapid Thermal Ultrathin Gate Oxide

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• Investigation of Strain-Temperature Stress on
  Rapid Thermal Ultra-thin Gate Oxide

Student Chia-Wei Tung ??? Advisor Jenn-Gwo Hwu
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Investigation of Strain-Temperature Stress on
Rapid Thermal Ultra-thin Gate Oxide
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• As the IC technology advanced toward ever-smaller
  geometry, this oxide layer has also been scaled
  down in thickness to keep the performance of the
  transistor from degrading.

• However, as technology downscaling causes greater
  power and package densities, thermal effects
  become significant in increasing numbers of
  designs.

• With the wafer size from 6inch to 8inch or
  12inch, wafer cutting become more inevitable in
  the upper stream package and testing foundries.

Investigation of Strain-Temperature Stress on
Rapid Thermal Ultra-thin Gate Oxide
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Dynamic scheme for applying strain-temperature
stress
100oC 30sec
Quartz holder
cool down and make in situ measurement
Investigation of Strain-Temperature Stress on
Rapid Thermal Ultra-thin Gate Oxide
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Part 1 - In the form of a full wafer
Part 2 - In the form of a strip

• It is found that the ultra-thin gate oxides in
  the form of a strip treated thermal stress have
  larger current variation. However, the
  tensile-temperature stress samples remain the
  best properties than compressive-temperature and
  control samples.
• We found that the electrical pre-measurement will
  cause the leakage current on accumulation region
  increases, this phenomenon isnt occurred on the
  samples without scribing.
• To explain the phenomenon of electrical measuring
  influence, we suggest that electrons after
  electrical measuring are trapped at hidden trap
  precursors in SiO2 bulk then be activated when
  temperature stress so that percolation path is
  induced.

• Various strain-temperature stresses are
  demonstrated for studying the reliabilities on
  MOS capacitors, and the experiment results show
  that the tensile-temperature stressed oxides
  exhibit lower saturation current variation and
  improved breakdown endurance.
• The reason that we propose for advantages of
  tensile-temperature stress is that the defects
  and interface traps at the interfaces between
  SiO2 and Si are much better than the others.

Investigation of Strain-Temperature Stress on
Rapid Thermal Ultra-thin Gate Oxide