Micro-patterned SiO2/TiO2 films through photo and chemical reactions

#This invention relates to patterned silica films. More specifically, this invention relates to silica films created through attraction silica solvent to pre-deposited, patterned titania films.

#Silica gel is a core substrate for creating functionalized surfaces for separation sciences. Additionally, silica enables and enhances the chemical and thermal stability of the ligands attached to its surface. [Bermudez, V. Z., et al., 1999. Chem. Mater. 11, 569; Prado. A. G. S., Miranda, B. S., Dias, J. A. 2004. Colloids and Surface A: Physlcochem. Eng. Aspects, 242, 137.] The active silanol groups on silica gel surface can react with organosilyl groups which contain the desired functional groups. This creates a variety of inorganic—organic hybrid surfaces which exhibit practical advantages such as structural stability, swelling behavior, thermal properties, accessibility of reactive centers, and insolubility in water and organic solvents. These hybrids have been widely applied in heterogeneous catalysis, metal ion and pesticide preconcentration, ion exchange, separation of metal ions, stationary phases for chromatography, biotechnology, and in controlled release pesticides.

#Silica is also a very important dielectric material, which has been widely used as a gate insulator and an interlayer insulator between metal wiring layers of semi-conductor or thin-film transistor displays and other related applications. [Saito, K., et al. 2003, Thin Solid Films, 430, 287.] Furthermore, with the embedding of metal nano-particles (e.g., Ag, Cu), the potential applications of Si02 as an insulator in non-linear optical systems are attractive for future ultrafast networks and circuits ahead of semiconductor devices. [Takeda. Y., Kishimoto, N., 2003 Nucl. Instr. Meth. B, 206, 620.]

#For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which:

#FIG. 1 is a set of scanning electron micrograph (SEM) images of the micropatterned films of (A) TiO2; (B) SiO2/TiO2; (C) amino-silylated SiO2/TiO2; and (D) TiO2 amino-silylated SiO2/TiO2.

#FIG. 2 is a series of graphs depicting the elemental analysis of the films of (A) TiO2; (B) SiO2/TiO2; and (C) amino-silylated SiO2/TiO2 on a copper substrate under SEM-EDS.

#A simple but inventive, non-etching related method is disclosed for making patterned Si02 films over Ti02 (Si02/Ti02) under room temperature and ambient atmosphere in a short period (typically, less than 2 hours) through convenient photo and chemical reactions. The patterned Ti02 film is fabricated through photo-irradiation of a photosensitive organic-titanium film using a mask. Si02 particles are generated from silicate solution by adjusting pH values to 10 to 8 with HCl. The pre-deposited Ti02 film has a strong attraction on Si02 particles, leading to the instant formation of Si02 film over the Ti02 film. The silica films are also amino-silylated with 3-aminopropyltriethoxysilane toward applications such as patternable, location-specific silica-based separation and purification.

#1. Photo-Sensitive Ti-Containing Gel Films

#Ti-alkoxide derived from the reaction of titanium tert-butoxide and benzoylacetone and its hydrolysate are UV-sensitive to generate Ti02. [Tohge N., Zhao, G., Chiba, F., 1999 Thin Solid Films 351, 85.] Micro-patterned TiO2 is made as described by Tohge et al. with minor modification. Briefly, the stock solution of the reaction mixture (Ti solution) uses 10 mg of benzoylacetone, 20 μL of Ti(O-nBu)4, 1 mL of CH3Cl and 100 μL of propylene glycol for enhancing viscosity and decreasing evaporation rate of the solution. Film deposition occurs via dispensing the Ti-solution on the top of the desired surfaces, with spinning at 1,500 rpm for 30 seconds to ensure the uniform distribution of organic substance, then soft bake the substrate on a hot plate (120° C.) for 10 seconds. The photosensitive film is exposed to UV (Mercury-Xenon lamp, 3500 mW/cm2 at 365 nm) for 8 minutes and rinsed with ethanol or acetone to remove the Ti-solution residue. This is followed by rinsing with deionized water.