Synthetic Control and Properties of Processible Poly(Methylsilsesquioxane)S
- PDF / 41,068 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 41 Downloads / 149 Views
SYNTHETIC CONTROL AND PROPERTIES OF PROCESSIBLE POLY(METHYLSILSESQUIOXANE)S Jin–Kyu Lee,* Kookheon Char, & Hie-Joon Kim,* Hee-Woo Rhee,+ Hyun-Wook Ro,* Dae Young Yoo,* and Do Y. Yoon.* *School of Chemistry and Molecular Engineering and &School of Chemical Engineering, Seoul National University, Seoul 151-742, Korea + Department of Chemical Engineering, Sogang University, Seoul 121-742, Korea
ABSTRACT Processible poly(methylsilsesquioxane)s (PMSSQs) were prepared in THF solution under nitrogen atmosphere in the presence of HCl catalyst. It was found that various reaction parameters such as concentration, temperature, reaction time, the amount of water, and the amount of acid catalyst could affect the molecular weight and the amount of functional end groups of PMSSQ samples. Thin films prepared from our PMSSQ samples by spin -coating followed by curing to 420oC exhibited a much better crack resistance than those presented in the literature, while the dielectric constant remained practically the same, i.e., ca. 2.7. INTRODUCTION Silsesquioxanes with empirical formula of (RSiO3/2)x, where R is hydrogen or an organic group, have been studied for many years since the first commercialization of silicone polymers as an electronic insulation materials at high temperature.1 Poly(phenylsilsesquioxane), PPSSQ, was the most widely studied material and many well-controlled synthetic methods were patented.2-4 Recently, silsesquioxanes have again attracted much attention as a promising candidate for a low dielectric insulator in semiconductor industry. Since semiconductor devices are becoming smaller and device packing densities are increasing rapidly, both signal delays due to the combined resistance and capacitance (RC) coupling and the crosstalk between metal interconnects have been found to be a serious problem. 5,6 According to the International Technology Roadmap for Semiconductors, when the dimension in integrated circuits shrinks to 0.13 µm around year 2002, this interconnect delay is believed to dominate the overall device cycle time.7 In addition to switching the metal electrode from Al to more conductive Cu, therefore, the introduction of low-dielectric insulator materials to the integrated circuits becomes another key requirement. Many researchers have tried to decrease the dielectric constant of an insulator by incorporating nanometer size pores in polymer matrices.8 Among many candidates for the insulators, the inorganic/organic polymer hybrid system shows quite interesting and promising results, where silicon based polymers such as poly(methylsilsesquioxane) (PMSSQ) were used as a matrix and organic oligomers (known as a porogen) were introduced to generate pores within the matrix.9 PMSSQ has been well known as an insulator matrix owing to its attractive low dielectric constant of ca. 2.7, low moisture absorption, excellent thermal stability up to 500oC, and reasonable mechanical hardness. 1, 10 Synthetic methods for preparing soluble and stable PMSSQ by acid or base catalyzed hydrolytic polymerization of methyltrifu
Data Loading...
