Cheng-Tyng Yen

Effects of slurry formulations on chemical-mechanical polishing of low dielectric constant polysiloxanes: hydrido-organo siloxane and methyl silsesquioxane

In this study, the film properties and chemical-mechanical polishing (CMP) characteristics of the low dielectric constant polymers hydrido-organo siloxane and methyl silsesquioxane are presented. The molecular structure and film properties of both polymers were characterized by their Fourier transform infrared spectra, refractive indices, dielectric constants, and atomic force microscopy diagrams. The CMP characteristics were studied by using different kinds of slurries and surfactants. The investigated slurries included SiO2 based slurry (SS-25), ZrO2 based slurry (Al), and Al2O3 based slurry (8104/H2O). Three kinds of surfactants were used to increase the contact area between the abrasive and polymer surface and thus polishing results were affected, which included nonionic Triton X-100, anionic dodecylsulfate sodium salt, and cationic tetramethylammonium hydroxide. The experimental results suggest that the organic content, the hardness and charge status of the abrasive, the polarity and charge status of...

Synthesis and characterization of poly(methyl silsesquioxane)???titania optical thin filmsElectronic supplementary information (ESI) available: FE-SEM diagram of MSQT60. See http://www.rsc.org/suppdata/jm/b2/b207390k/

Poly(methyl silsesquioxane) n(MSQ)–titania optical thin films were synthesized and characterized in this study. An MSQ precursor with a mixed cage and network structure was prepared first, which had end groups of Si–OH and Si–OCH3. Then, it was reacted with titanium(IV) n-butoxide, followed by spin-coating and multi-step curing to form the optical thin films. The FTIR spectra suggest successful bonding of MSQ and titania. The prepared films were very uniform with an amorphous nanoscale titania segment from the results of FE-SEM, AFM, and XRD. Excellent thermal stability was found for the prepared MSQ–titania materials. The optical properties of the prepared MSQ–titania films could be tuned by the titania content. By increasing the titania content from 10.6 to 41.6 wt.%, the absorption edge and refractive index were increased from 291 to 310 nm, and from 1.394 to 1.561, respectively. These results are attributed to the growing size effect of the titania segment. Optical planar waveguides were fabricated from the synthesized MSQ–titania films on top of a thermal oxide using a silicon wafer as the substrate. The optical loss of the studied planar waveguide decreased from 0.31 to 0.18 dB cm−1 with increasing titania content. This resulted from a reduction of the C–H bonding density due to the increasing titania composition.

Tuning Near-Infrared Optical Properties of Aromatic Model Compounds by Substituents

In this study, the effects of substituents on the near-infrared (NIR) absorption spectra of model compounds were examined theoretically and experimentally, including benzene (B), fluorobenzene (FB), 1,4-difluorobenzene (DFB), and 1,4-bis(trifluoromethyl) benzene (6FB). It was found that a stronger electron-withdrawing substituent resulted in a smaller C–H bond length and thus a blue-shifted overtone position. Thus, the order of B > FB > DFB > 6FB was found for the positions of C–H fundamentals and overtones. The variations of optical windows were primarily influenced by the C–H molar density as well as by the shifting of the absorption band by the substituent. A pseudo compound (PC) with the same C–H number density as the 6FB but with the same band position as B was used to address the effect of a polarized substituent on the optical window. It was found that 6FB could have the optical window at the lower wavelength regions of the S-band (1480–1530 nm) and C-band (1530–1570 nm) but that of the PC at the higher wavelength regions of the C-band and L-band (1570–1610 nm). The present study provides another approach for designing new organic polymers for optical waveguides besides the current approach of reducing the C–H number density.