Patterned polymer multilayers as etch resists

This paper describes the synthesis and characterization of patterned polymer multilayers on self-assembled monolayers (SAMs) and the use of these structures as etch resists for gold. The procedure used to build polymer multilayers consisted of five steps: (i) A polar thiol-HS(CH2)(15)COOH-was patterned on gold or silver films by microcontact printing (mu CP) with a poly(dimethylsiloxane) (PDMS) stamp. (ii) The patterned surface was placed in a solution containing CH3(CH2)(15)SH to form a nonpolar, methyl-terminated SAM on the remaining bare metal surface. (iii) The regions of the SAM patterned with CO2H groups were activated for further chemical reaction by conversion into interchain anhydride groups. (iv) The activated substrate was allowed to react with poly(ethylene imine) (PEI, branched chain, M-w 750 000). (v) A second polymer layer was attached to the PEI layer by allowing the amine-terminated surface to react with poly(octadecene-alt-maleic anhydride) (POMA, M-w 30 000) or poly(styrene-alt-maleic anhydride) (PSMA, M-w 350 000). This procedure (alternating reaction with PEI and POMA/PSMA) was repeated up to five times to increase the number of layers and the thickness of the patterned structure. The polymer multilayers were characterized using atomic force microscopy (AFM), ellipsometry, and polarized infrared external reflectance spectroscopy (PIERS). The stability of the films was demonstrated by using the patterned polymer multilayers as etch resists and by measuring their breakdown voltages.