Ph'D' Dissertation

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Ph.D. Dissertation
Process Development and Characterization of Al2O3
High-k Gate Dielectrics Prepared by Anodization
and Nitric Acid Oxidation for MOS Devices
Student Szu-Wei Huang Advisor Prof. Jenn-Gwo
Hwu Graduate Institute of Electronics
Engineering National Taiwan University
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About This Work

• Al2O3 High-k Gate Dielectrics on p-Si Prepared
  by Anodization
• Al2O3 High-k Gate Dielectrics on n-SiC Prepared
  by HNO3 Oxidation
• Lateral Nonuniformities of Effective Oxide
  Charges in Al2O3 High-k Gate Dielectrics

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Results

• Both DC and DAC anodization were successfully
  used to prepare Al2O3 high-k gate dielectrics,
  and the obtained devices show excellent
  electrical characteristics.
• 4H-SiC MOS Capacitor with ultra-thin Al2O3 gate
  dielectric is fabricated by low thermal budget
  room temperature HNO3 oxidation and has the
  potential to be the gate dielectric of SiC-based
  devices.
• The high frequency Termans method is utilized
  to detect the lateral nonuniformity of effective
  oxide charges, and the negative effective
  interface trap density is shown to be resulted
  from the lateral nonuniformity of effective oxide
  charges but not interface traps.

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Conclusions

• Two simple, cost-effective, and very low thermal
  budget processes for preparing Al2O3 high-k gate
  dielectrics are proposed in this thesis.
• The obtained MOS devices show excellent
  electrical characteristics and imply the
  applicability of integrating the proposed
  processes into CMOS technology.
• Termans method for extracting Dit is utilized
  to inspect the LNU charges and it conduces a
  simple and effective technique to the charge
  trapping issues.