三甲基氯硅烷对纳米多孔二氧化硅薄膜的修饰

Modification of Nanoporous Silica Film by Trimethylchlorosilane

以正硅酸乙酯为先驱体,采用溶胶-凝胶法,结合旋转涂胶、超临界干燥工艺在硅片上制备了纳米多孔SiO2薄膜.用三甲基氯硅烷(TMCS)对该SiO2薄膜进行了表面修饰,采用FTIR、TG-DTA、AFM和椭偏仪等方法研究了TMCS修饰前后薄膜的结构、形貌、厚度与介电常数等性能.超临界干燥后的SiO2薄膜含有Si-O-Si与Si-OR结构,呈疏水性.在空气中250℃以上热处理后SiO2薄膜因含有Si-OH而呈吸水性.TMCS修饰后的SiO2薄膜在温度不高于450℃时可保持其疏水性和多孔结构.SiO2薄膜经TMCS修饰后基本粒子和孔隙尺寸增大,孔隙率提高,介电常数可降低至2.5以下.

Crack-free homogeneous nanoporous silica films on silicon wafers have been synthesized via supercritical drying of wet gel films that were obtained by spin coating the polymeric silica sol using sol-gel method with tetraethoxysilane (TEOS) as precursor. The silica film was composed of Si - O - Si and Si - OR characterized by FTIR and was hydrophobic. But the silica film became hydrophilic because of Si - OH group after it was heat treated above 250 degreesC in air. So the silica film was modified by trimethylchlorosilane(TMCS) in order to get hydrophobic, thermal stable film with low dielectric constant. The modified silica film was characterized by FTIR, AFM and spectroellipsometer. The modified silica film can keep hydrophobic and its nanoporous structure at temperature lower than 450 degreesC in nitrogen. The sizes of SiO2 primary particles and pores of silica film became larger after modification. The modified silica film had higher porosity and lower dielectric constant. Its dielectric constant could be reduced to below 2.5.