Transition from superhydrophilic to superhydrophobic of silicon wafer by a combination of laser treatment and fluoropolymer deposition

We propose a novel approach for synthesizing silicon surfaces ensuring arbitrary apparent contact angle within the range from 0° to 170° for water. Superhydrophilicity of silicon substrates is achieved by nanosecond laser treatment and subsequent change in the contact angle is obtained by deposition of fluoropolymer films with different thicknesses by a hot wire chemical vapor deposition (HWCVD) method. The deposited film thickness needed to obtain superhydrophobicity was determined. The wettability properties of the produced fluoropolymer–silicon system are analyzed using the Wenzel and Cassie theories. (paper)