Papers by Author: Yao Yi Cheng

Abstract: This paper presents study on porous Hydrogen Silsesquioxane (HSQ) of dielectric constant near 2. Porous HSQ solution was spin-on coated and then treated by wet ammonia. During the treatment, HSQ film went through a sol-gel process. Pores were uniformly formed in HSQ film after a baking process to remove solvent. A solid network structure of porous HSQ was then formed after a high-temperature curing process. In this work, we compared the properties of porous HSQ with varying process time of wet ammonia treatment and curing temperature. Change of chemical structure was analyzed by Fourier transform infrared (FTIR) spectrometry. We found that the cage structure of porous HSQ was reduced but the network structure was enhanced as treatment time of wet ammonia increased. Hardness and Young’s modulus were measured by nano-indentation technique. The adhesion strength of porous HSQ with silicon carbide was measured. Surface properties and electrical characterization of porous HSQ with varying process conditions have also been examined.

Abstract: Polyimide (PI)-based nanocomposites were prepared by the in-situ generation of organic silica nano-particles through a sol-gel process, combined with spin coating and multi-step curing process. In this study, silica nano-particles were introduced into the PI matrix to promote its thermal properties. Nanometer-scale composites were successfully obtained from poly(amic acid) (PAA) mixture loaded with silica. 3,3’,4,4’- Biphenyl tetracarboxylic dianhydride (BPDA) and p-phenylenediamine (p-PDA) were employed to synthesize the PAA precursor. The hybrid thin film was prepared from aminoalkoxysilane-capped PAA and tetraethoxysilane (TEOS). In this work, we investigated the effect of coupling agent, 3-aminopropyltriethoxysilane (APrTEOS). The TGA results indicate that the thermal stability of the nanocomposites can be enhanced as silica content increases. Without the incorporation of APrTEOS, less improvement can be achieved.