Novel Method of Surface Activation for Electroless Metal Plating
Jon Englert1, Amy Ng2, and Anthony Muscat3
1Department of Chemistry and Biochemistry, 2Department of Materials Science and Engineering,
3Department of Chemical and Environmental Engineering, University of Arizona
Arizona Space Grant Consortium, Tucson, Arizona
April 17, 2010
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Metal Plating
• Corrosion and Wear Resistance
• Physical Properties
• Conductivity Characteristics– Lam Research: Wire Production
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Electroless Metal Plating
Process:Deposit a thin chemical layer on an object that can catalyze the nucleation of metal on its surface
– No electrical power required
– Plating on nonconductive surfaces
– Uniform plating on complex substrates
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Surface Activation for Electroless Metal Plating
Challenge:
Saturated monolayer required for uniform plating
Approach:Aminosilane self assembled monolayer (SAM) on SiO2 substrate to form a reactive amino-terminated surface
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SiO
O
O
NH2
SiO
O
O
NH2
SiO
O
O
NH2
SiO
O
O
NH2
SiO
O
O
NH2
SiO
O
O
NH2
OH
OH
OH
3-aminopropyltrimethoxysilane APTMS
Si
O
OO
NH2
Tri-functional aminosilane
SiO2
Common Surface Activation Methods
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Liquid: Exposure to aminosilane solution and extraction with solvents
Dilute Liquid: Exposure to highly diluted aminosilane in solvents
Atmospheric Vapor: Exposure to aminosilane at atmospheric vapor and extraction with solvents
[1] Petri D.F.; Wenz G.; Shunk P.; Schimmel T. Langmuir 1999, 15, 4520-4523.
Common Surface Activation Methods
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Vacuum Vapor MethodSamples are placed in the vacuum vapor reactor and pumped down
Pump valve is closed and samples are exposed to precursor vapor
System is purged of precursor vapor and the sample is removed
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•Fast deposition with less thickness variation
•No precursor dilution required
•Can be combined with vacuum controlled etching and plating processes
APTMS Vacuum Vapor Exposure
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Comparison of Activation Methods
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APTMS Surface Characterization
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Water contact angle on an amino-terminated surface is approximately 50 -70 ⁰ ⁰ 1
[1] Petri D.F.; Wenz G.; Shunk P.; Schimmel T. Langmuir 1999, 15, 4520-4523.
APTMS Exposure and ExtractionOther Solvents Used:•Acetone•Isopropyl Alcohol•Chloroform
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One cycle is one exposure and one extraction
SiO
O
O
NH
SiO
O
O
NH
SiO
O
O
NH2
SiO
O
O
NH2
APTMS Surface Characterization
Amino-terminated surface present throughout process suggesting polymerization
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APTMS Surface CharacterizationS1 = 6 cycles of 10min APTMS Exposure / 10min Toluene Extraction
S3 = 10min APTMS Exposure
X-Ray Photoelectron Spectroscopy (XPS) Analysis
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Current Work• Atomic Force Microscopy (AFM) and
Fourier Transform Infrared Spectroscopy (FTIR) of activated surfaces.
• Cobalt plating on activated surfaces
• Surface activation using APDES precursor
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Si
O
NH2
3-aminopropyldimethylethoxysilaneAPDES
Mono-functionalized aminosilane
Thank You!
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Vacuum Vapor Reactor Schematic
APDES Vacuum Vapor Exposure
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