Studying the Effects of Different Types and Different Particles Sizes On Porous Silica Low-K Thin Films

• Main Authors: Yu-Chiao Liu, 柳佑樵
• Other Authors: 萬本儒
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/67918218444782079190

碩士 === 國立臺灣大學 === 化學工程學研究所 === 94 === Mesoporous silica has been widely studied for low-k materials, because of it’s low dielectric constant (about 2), good thermal stability, and friendly-preparation procedures. However, the porosity in the film makes the mechanical strength insufficient. The improvement of mechanical strength of the films is essential. This research intends to solve the problem by making the films with small silica particles. The correlations among the particles size, the dielectric constant and mechanical strength of the films were systematically studied. Two different kinds of procedure to produce SiO2 particle colloids were used. The first one was the reflux procedure at 70℃ under acidic condition. The second one was the hydrothermal procedure at 95℃ under basic condition, and TPAOH or TBAOH was used as the template. The particle sizes were measured by HRSEM. The coating solution was a mixture of SiO2 colloids and Tween 80 at 30℃. The resulting solution was spin-on a 4-inch silicon wafer. Dielectric constant, leakage current density, mechanical strength and XRD results were applied to analyze the characteristics of the thin films. By using reflux procedure, the particle sizes were about 4.5nm after refluxing for 90 minutes. The particle sizes increased with the reflux time. The larger the particle sizes were, the better the mechanical strength of the films was However, the dielectric constant was slightly increased with the increase of the particle size. The leakage current densities of all the films were about 10-8 (A/cm2). By using hydrothermal procedure and TPAOH as the template, the particle size was found to increase from 10 nm to 30nm within 6 ~ 48 h hydrothermal treatment. There were defects on the surface of those films. Therefore, it was hard to measure the dielectric constant precisely. Only one data of the dielectric constant could be measured and the value was 2.9. The mechanical strength decreased with the increase of hydrothermal period. When TBAOH was used as the template, no particle was observed in the solution. The hardness of all the films was higher than 1GPa. However, all the films also have higher values of dielectric constant, then the leakage current densities of the films from the hydrothermal procedure were all about 10-6(A/cm2)~10-7(A/cm2).