daytona beach conference aluminum oxide and silicon nitride thin films as (2)
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ant-corrosion study of Al2O3 and SiN as the thin film coatingTRANSCRIPT
ALUMINUM OXIDE AND SILICON NITRIDE THIN FILMS AS ANTI-CORROSION LAYERS
C. Qu1, P. Li1, J. Fan1, D. Edwards1, W. Schulze1, G. Wynick1, R. E. Miller1, L. Lin1, Q. Fang2, K. Bryson3,
H. Rubin4, and X. W. Wang1*
• Alfred University, Alfred, NY 14802, USA• Oxford Instruments Plasma Technology, Yatton, Bristol BS49 4AP, UK• Duke University, Durham, NC27708, USA• Plasma-Therm, St. Petersburg, FL 33716, USA
• Acknowledgment: DOE USCar Program
• Background InformationNew Automotive Engine & Other Parts:Magnesium-Aluminum Alloy Materials
Fasteners: Carbon Steel
Potential Problems:Galvanic Corrosion
Thin Films
Aluminum oxideE-beam Evaporation Technique
Silicon nitridePlasma Enhanced Chemical Vapor Deposition
(PECVD)
Cerium OxideUV Curable Layer
E-beam Evaporation Technique
– Target: Aluminum oxide
3.Power: 8 KV, 0.1 APressure: 2 x 10-4 torr
– Post deposition heat treatment in ambient environment @ 350 °C for 40 min.
– UV curable materialCe(OCH2CH2OCH3)3
Cured with a UV lamp with the wavelength of 184-400 nm
E-beam Evaporation
• VPT
Plasma Enhanced Chemical Vapor Deposition (PECVD)
• Precursor: Silane, ammonia, nitrogen
– Pressure: 0.1 torr– Substrate holder temperature : 275 oC– Shower head temperature: 100 oC
Plasma Enhanced Chemical Vapor Deposition (PECVD)
• Trikon
SiH4
NH3
N2
RF
Vacuum
Shower head
Shower head
Substrate holder (Bottom electrode)
Top electrode
Issue
• Coverage of steel substrates – Macro-- Defects / Scratches– Micro– Cluster sizes / shapes
Control
Defect
Impedance of Control
Single-layer Aluminum Oxide Thin Film
• 150 nm
Impedance
• 200 nm, 700 nm
Post Deposition
• Post-deposition heat treatment– Aluminum oxide thin films were heat treated at
350 °C for 40 min.– Second deposition of aluminum oxide after the
heat treatment
• UV-curable material as the top layer
Comparison
• UV Curable Coating, Al2O3, UV Curable Coating on Al2O3
Single-layer Silicon Nitride Thin Film
• 60 nm
Increasing Thickness
• 300 nm
Thicker
• 600 nm
Thickest
• 850 nm
Impedance
• Silicon Nitride
Impedance Modulus Comparison
• Single Layer Silicon Nitride vs. 3-layer Aluminum Oxide
Progress• Increasing impedance
Control
Single-layer Aluminum Oxide
Single-layer Aluminum Oxide w/ Heat Treatment
Double-layer Aluminum Oxide w/ Heat Treatment
Double-layer Aluminum Oxide w/ Heat Treatment and UV-curable material on the top
Silicon Nitride via PECVD
Density of Aluminum Oxide Film
– Density: Estimated via ellipsometry
• Single-layer aluminum oxide thin films with different thickness:
83%• Double-layer aluminum oxide thin films with
heat:92%
Conclusion
• For the two-layer aluminum oxide film fabricated with three-steps, the highest impedance modulus value at 0.01 Hz is approximately 4.6x105 Ohm-cm2
• With an additional UV curable cerium oxide layer, the impedance modulus value is increased to approximately 2.1x106 Ohm-cm2
• For 850 nm silicon nitride film fabricated with one-step, the impedance modulus value is 1.4 X 106 Ohm-cm2
• Coverage of the defect areas: related to impedance