Deep-UV Photochemistry and Patterning of (Aminoethylaminomethyl)phenethylsiloxane Self-Assembled Monolayers

• Published in: Advanced functional materials Vol. 16; no. 6; pp. 774 - 783
• Main Authors: Chen, M.-S., Dulcey, C. S., Chrisey, L. A., Dressick, W. J.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 04.04.2006; WILEY‐VCH Verlag
• Subjects: Electroless deposition; Photopatterning; Self-assembled monolayers; Template-assisted assembly
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.200500744

The 193 nm photochemistry of (aminoethylaminomethyl)phenethylsiloxane (PEDA) self‐assembled monolayers (SAMs) under ambient conditions is described. The primary photodegradation pathways at low exposure doses (< 100 mJ cm–2) are benzylic C–N bond cleavage (ca. 68 %), with oxidation of the benzyl C to the aldehyde, and Si–C bond cleavage (ca. 32 %). Amine‐containing photoproducts released from the SAM during exposure remain physisorbed on the surface, where they undergo secondary photolysis leading to their complete degradation and removal after ca. 1200 mJ cm–2. NaCl(aq) post‐exposure rinsing removes the physisorbed materials, showing that degradation of the original PEDA species (leaving Si–OH) is substantially complete after ca. 450 mJ cm–2. Consequently, patterned, rinsed PEDA SAMs function as efficient templates for fabrication of high‐resolution, negative‐tone, electroless metal and DNA features with good selectivity at low dose (i.e., ca. 400 mJ cm–2) via materials grafting to the intact amines remaining in the unirradiated PEDA SAM regions. Monolayer templates of (aminoethylaminomethyl)phenethylsiloxane, suitable for fabrication of high‐resolution, negative‐tone, electroless metal or fluorescently labeled DNA features, can be fabricated readily by direct monolayer patterning using deep‐UV (193 nm) at low exposure doses (approximately 400 mJ cm–2). The figure shows an example of DNA (red) patterning.