Preparation And Photopatterning Of "Swallow Tailed" Copolymer LB Films

In this paper, a series of new "Swallow tailed" photoresists containing amphipathic molecule N-Alkyl methyl acrylamide as film components and a seris of light sensitive components containing Allyl-malonic acid-diadamantane ester (DAdMAMA), Allyl-malonic acid-cyclohexyl Methyl ester, and Adamantane methyl methacrylate (AdMMA), Cyclohexyl methyl methacrylate (CyMMA), Menthol methyl methacrylate (MeMMA)(Fig1); The composition and molecular weight of these copolymers were characterized by1H NMR and gel permeation chromatography (GPC), respectively. Their properties of film-forming, lithographic performance and lithography mechanisms were also explored. Fig1Polymer structure diagramThe monolayer behavior at air/water interface and Langmuir film transfer ability of copolymers were determined by the length and the mole fraction of alkyl in acrylamide in copolymers. The copolymer containing high mole fraction of hexadecyl group could form condensed monolayer on air/water interface, and could be transferred to different substrates to form homogeneous LB films. Through studying, better photopatterning of copolymers, h2a20(HDMA:DAdMAMA=8:2); h1a40(HDMA:AdMMA=6:4) and h2d30(HDMA:DCyMAMA=7:3), could be obtained.Take p(HDMA-DAdMAMA)[h2a20] as an example, the linear relationship between the absorbance and the number of deposited layers in Figure2suggested that a regular deposition of the copolymer monolayer took place, resulting in uniform h2a20LB films. We observed that the absorbation was propotion to monolayer deposited from2and26layers, and then slowly increase because of lowing of transfer ratio, indicating that regular multilayers ranging from2to26layers could be formed. Fig2UV absorption of p(HDMA-AdMAMA)[h2a20] LB films (Inset:plots of the absorbance at192nm vs. the numberof LB films deposited).AFM planar graph and3-D images of15layers of h2a20LB films were measured (Figure3). High orientation and order of the molecules in LB films could be observed, suggesting that a regular deposition of the copolymer monolayer took place.Figure3AFM planar graph (left) and3-D (right) images of15layers of h2a20LB films on silicon.Photolithographic properties of these copolymers were also investigated. Photopatterns15layers of h2a20LB films with the resolution of0.75μm could be obtained by deep UV irradiation, followed by development with acetone or TMAH solution (Figure4).Figure4Optical micrograph of photopatterns of15layers p(HDMA-DAdMAMA)[h2a20] LB films on silicon. Right:Optical micrograph of etched pattern of chrome films on glass substrate.The photodecomposition mechanism of h2a20LB films irradiated with deep UV light was explored. UV-vis, FT-IR, GPC, TG-DSC were used to explore characteristics of h2a20LB films irradiated. Possibly photodecomposition mechanism of h2a20LB films is shown in Fig5. Fig5Plausible photodecomposition mechanism of h2a20...