Fabrication and surface treatment of silicon mold for polymer microarray

Abstract

We present the results of our development of deep silicon etching process and surface treatment method for 40∼50 μm deep silicon mold. Silicon mold was fabricated with conventional photolithography and deep silicon etching. A ‘modified Bosch process’ was developed for positively tapered sidewall profile that will allow the release of the mold from a polymer substrate after UV embossing without breakage of the silicon mold. Deeply etched silicon shows high etch rate (>1.2 μm/min) and positively tapered sidewall slope (∼85°). In this paper, silicon mold was treated with plasma-polymerized fluorocarbon (PPFC) film using ICP reactor for easier release and better integrity of molded structure. These PPFC films were characterized by deposition rate, surface roughness, and contact angle with various deposition conditions. PPFC film deposited with ICP reactor showed high deposition rate (∼80 nm/min) and smooth roughness (∼1.5 nm). The result of contact angle measurement confirmed that silicon mold treated with PPFC film has strong hydrophobicity ( θ c>108°). Finally, polymer microarray was successfully replicated from silicon mold. To find that the replication has been performed successfully, the released polymer microarray was also examined with SEM and surface profiler.