Preparation of Porous Silica Low-k Films by Using Different Concentration of Structure Directing Agent TPAOH

• Main Authors: Chiung-Yun Chang, 張瓊云
• Other Authors: Ben-Zu Wan
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/15333586354640615486

碩士 === 國立臺灣大學 === 化學工程學研究所 === 101 === The syntheses of coating solutions with pure silica MFI-type zeolite for the preparation of porous low dielectric constant (low-k) films were reported in literatures. In our previous study, short hydrothermal process for producing coating solutions mainly containing noncrystalline silica has been developed for the preparation of low-k films. The films with not only a k value below 2 but also a high mechanical strength can be obtained. To continue with the research, the effect of concentration of tetrapropylammonium hydroxide (TPAOH, as structure directing agent) on properties of low-k films has been investigated. In this research, the motivation is to study the effect of TPAOH concentration on properties of noncrystalline silica nanoparticles (such as particle size and surface hydrophilic property) and on properties of corresponding low-k films (such as pore properties, dielectric constant, leakage current density, mechanical properties and surface morphology). The properties were examined and discussed in details. It is found that the nanoparticle size decreases with the increase of the TPAOH concentration in the precursor solution. In addition, the content of silanol groups on the surface of silica nanoparticles would also be influenced by the TPAOH concentration. They increase with the increase of the TPAOH concentration. The silica nanoparticles with different surface silanol groups should possess different hydrophilic properties, and therefore would influence the behavior of surfactants in the coating solutions. The lower content of surface silanol groups would lead to the formation of more aggregates of surfactants, resulting in the existence of micro-sized pore on the film surface and thereby causing the electrical properties and mechanical properties of the films to become worse. In addition, the lower content of surface silanol groups on silica nanoparticles would have a negative effect on crosslink formation between different silica nanoparticles, which would contribute to the decrease of mechanical strength of the films. In contrast, the films preprared form silica nanoparticles with higher content of surface silanol groups can possess a uniform surface, an ultra-low k value of 1.94, a high hardness of 1.50 GPa, a high elastic modulus of 13.36 GPa, and a low leakage current density of 5.69×10-9A/cm2.