以溴化十六烷基三甲銨為模板劑 對低介電材料之結構與性質之影響

Abstract

較小且分散均勻的孔洞具有較優良的機械性質，因此本研究針對使用溴化十六烷基三甲銨為起孔劑，由於其較高的電位 (~100 mV)以及在四乙氧基矽烷中長程有序排列的結構；進一步檢視其在甲基三甲氧基矽烷與四乙氧基矽烷之混合膜中結構與性質之關係，並比較與在四乙氧基矽烷系統中之差異。 甲基三甲氧基矽烷/四乙氧基矽烷混合膜是以莫耳比 3:1的比例混和，較多的終端基(Si-CH3)可使介電常數降得更低，然而甲基卻會妨礙微胞的形成並阻礙其長程有序的排列，因此從掠角入射X光小角度散射二為散射圖示中得知，僅有短程有序的排列。當添加量從1.5 wt%提升至3 wt% 微胞尺寸由2.2上升至2.7 nm 是由於微胞的團聚數量尚未達飽和，而3 wt%到10 wt%則維持在約2.6 nm附近，在經過固化處理孔洞尺寸變化也小於10%，可知帶較高電位的起孔劑可良好的分散避免團聚。溴化十六烷基三甲銨有利於矽醇基的縮合反應形成矽氧烷的結構，在此研究中亦發現隨溴化十六烷基三甲銨增加，矽醇基殘留量較未添加來的少，此現象有利於結構及性質亦將在文中詳細描述

Smaller and well dispersed pores create better mechanical properties. In the study, Cetyltrimethylammonium bromide (CTAB) is selected as pore generator (porogen) because of the high surface zeta potential (~100mV) and long range order arrangement in TEOS system. Furthermore, the structure-property relationships of Methyltrimethoxysilane (MTMS)/ Tetraethylorthosilicate (TEOS)/ CTAB hybrid thin films are examined and compared to TEOS/CTAB system. The MTMS/TEOS hybrid films are combined with the molar ratio MTMS/TEOS=3. The more terminal group (Si-CH3) in the film the lower dielectric constant can be achieved. However, the formation of micelles is hindered and the arrangement is also impeded by the methyl group. Therefore, micelles/pore with long range order structure cannot be obtained but size only increase slightly after curing process in the thin film which can be observed from grazing incidence small angle X-ray scattering (GISAXS). In addition, the residual of silanol groups (Si-OH) decrease with increasing CTAB after curing process due to CTAB is benefit the condensation reaction of siloxane. The influence is benefit structures and properties will elaborate in the following sections.