Thin ALD Al2O3 films grown on nInAs and pSi

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Thin ALD Al2O3 films grown on n-InAs and p-Si

• Bin Wu, Guangle Zhou, Grace Xing, Alan Seabaugh
• University of Notre Dame
• June 05, 2008

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Outline

• ALD system at Notre Dame
• Experiment description
• Physical properties of Al2O3 films on InAs and Si
  substrates
• Electrical characterization of MOS structures
• Summary

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Cambridge NanoTech Inc. ALD S100
Flow rate20sccm Water vapor pulse time
15msec TMA pulse time 15msec
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ALD Al2O3 MOS capacitance structures
ALD Al2O3
18 36 73 cycles

• Three different thicknesses of Al2O3 films are
  deposited at 200 C on both n-InAs and p-Si
  substrates.
• Al top contacts are formed through shadow mask
  and followed with back contacts deposition.
• Three annealing temperatures are studied, 250,
  300, and 350 C. Annealing is done in N2 ambient
  for 30 s at each temperature.

VASE characterization
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Sample set
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Annealing effects on film surface roughness
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Annealing effects on film thickness and
refractive index
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Vertical I-V of 18-cycle Al2O3 on n-InAs
Measured on 150 µm diameter Al dots
Absolute current
Current Density
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Vertical I-V of 36-cycle Al2O3 on n-InAs
Measured on 150 µm diameter Al dots
Absolute current
Current Density
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Vertical I-V of 73-cycle Al2O3 on n-InAs
Measured on 150 µm diameter Al dots
Absolute current
Current Density
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Vertical I-V of as-grown 18, 36 and 73-cycle nm
Al2O3 films on p-Si
Measured on 150 µm diameter Al dots
Absolute current
Current Density
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Vertical I-V of as-grown 18, 36 and 73-cycle nm
Al2O3 films on n-InAs
Measured on 150 µm diameter Al dots
Absolute current
Current Density
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Exponential change of tunneling current density
with thickness - as-grown films
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Summary

• Al2O3 films have been deposited on n-InAs and
  p-Si substrates by ALD at 200 C and MOS
  structures are formed
• Al2O3 films have been char
• Annealing in N2 ambient at 250, 300 and 350 C
  increases the leakage current through the oxide