Photochemical Modification of Silicone Films Using F₂ Laser for Selective Chemical Etching

Abstract

Silicone ([SiO(CH3)2] n ) films were photochemically modified into SiO2 by irradiation with a 157 nm F2 laser. The dissociation of Si–CH3 bonds of silicone simply depended on the photon number of the F2 laser. The quantum yield of the modification was estimated to be approximately 1×10-2. Mechanisms of oxidation and O–H production in the modified films were clarified. The depth of the modification was not limited by the absorption coefficient of silicone because SiO2 of the modified films is transparent for the F2 laser. A fine pattern of the 1.5-µm-thick silicone films could be fabricated by immersing the modified samples in 0.2 wt% hydrogen fluoride solution.

Fs-laser processing of polydimethylsiloxane

“…In particular, UV nanosecond laser pulses (e.g., KrF, ArF, and F 2 ) are largely applied for fabrication of optical elements, 7-9 deposition of thin films, 10-12 modification of optical properties, [13][14][15] and surface processing or functionalization. [16][17][18][19][20][21][22] For example, KrF excimer laser (k ¼ 248 nm) processing of siloxane-based flexible silicone rubber is used to photo-decompose the sample surface changing the surface relief. 2,[22][23][24] Information on the changes to the PDMS structures irradiated by ns-laser pulses is typically obtained by l-Raman measurements.…”

Formation of textured Al thin film on periodic microswelling structure fabricated on silicone rubber surface to realize superhydrophobicity

“…We verified new methods for photochemical surface modification of silicone rubber using vacuum ultraviolet lasers. Particularly, we previously reported that when silicone is irradiated with an F 2 laser (wavelength: 157 nm), only exposed portions are modified into silica glass (SiO 2 ) . Based on that result, we conducted fundamental research to fabricate flexible optical devices through directly forming SiO 2 optical waveguides and microlenses on silicone rubber .…”

“…Particularly, we previously reported that when silicone is irradiated with an F 2 laser (wavelength: 157 nm), only exposed portions are modified into silica glass (SiO 2 ). [6][7][8] Based on that result, we conducted fundamental research to fabricate flexible optical devices through directly forming SiO 2 optical waveguides and microlenses on silicone rubber. [9][10][11][12] In addition, we applied such photochemical surface modification to silicone-coated polycarbonate to demonstrate a possibility of developing next-generation plastic windows for electric vehicles.…”

Crack Suppression of Transparent Protective Layer on Polycarbonate Formed by Fluorine Laser

“…The development of PC with high wear resistance property that can resist against wiping by wiper is strongly desired. We already found that surface of silicon rubber could be photochemically modified to silica glass (SiO 2 ) by irradiating the fluorine (F 2 ) laser with the wavelength of 157 nm [6][7][8]. Based on the experimental results, we further formed lightguide and microlens made of SiO 2 on silicon rubber substrate, thereby establishing the fundamental result of flexible light devices [9][10][11][12].…”