Investigation of the mechanism of electroless deposition of copper on functionalized alkanethiolate self-assembled monolayers adsorbed on gold.
We have investigated the reaction pathways involved in the unseeded electroless deposition of copper on self-assembled monolayers (SAMs) adsorbed on Au, using time-of-flight secondary ion mass spectrometry, optical microscopy, and scanning electron microscopy. At 22 degrees C copper deposits on both -CH3 and -COOH terminated SAMs. No copper deposition is observed on -OH terminated SAMs because the hydroxyl terminal groups react with formaldehyde in the plating solution, forming an acetal which prevents Cu deposition. At higher deposition temperatures (45 degrees C), no Cu is observed to deposit on -CH3 terminated SAMs because Cu2+ ions are not stabilized on the SAM surface. Copper complexes are still able to form with the -COOH terminal group at 45 degrees C, and so copper continues to be deposited on -COOH terminated SAMs. Copper also penetrates through -CH3 and -COOH terminated SAMs to the Au/S interface, suggesting that soft deposition techniques do not prevent the penetration of low-to-moderate reactivity metals through organic films.
Lu
Peng
P
Department of Chemistry and Center for Materials Innovation, Washington University in St. Louis, St Louis, MO 63130, USA.
Walker
Amy V
AV
D000327:Adsorption; D000473:Alkanes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008567:Membranes, Artificial; D010316:Particle Size; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
D000473:Alkanes; D008567:Membranes, Artificial; D013438:Sulfhydryl Compounds; D006046:Gold; D003300:Copper