超低介电常数介孔氧化硅薄膜的制备及其表征

Synthesis of Mesoporous Thin Silica Films with Ultra Low Dielectric Constant

研究了以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MeSi(OEt)_3)为混合硅源,十六烷基三甲基溴化铵(CTAB)为模板剂,采取旋涂技术,在硅晶片表面制备出二氧化硅透明薄膜,再经过正硅酸乙酯(TEOS)蒸汽孔壁强化后采用线性升温焙烧法脱除薄膜孔道内的模板剂,制备出具有超低介电性能的氧化硅薄膜。使用FTIR、XRD和SEM对样品进行了结构表征,并采用阻抗分析仪测量了薄膜的介电常数(k),纳米硬度计测量薄膜的弹性模量。介孔氧化硅薄膜在常温常湿条件下存放15d后,介电常数仍旧维持在超低值范围内,k=1.80,弹性模量大于6GP,很好地满足了其在超大规模集成电路中应用的要求。

Vapor phase treatment with tetraethyl orthosilicate （TEOS） was used to improve the performance of methylated mesoporous silica films spin-coated on silicon wafers. Subsequent calcination treatment led to formation of methyl-functionalized-silica films with high structural stability and hydrophobicity. XRD, FTIR results show that the films have high structural stability and hydrophobicity. SEM images indicate that TEOS treatment favors the formation of flat and integrated non-crack films. Dielectric constant （k） value of the films is ultra low, k≈1.74, and remains as low as 1.81 after aging in 25 ℃ and 50%-60%-relative-humidity environment for over 15 days. Mechanical strength （elastic modulus and hardness） is high enough to withstand the stresses that occur during the chemical mechanical polishing and wire bonding process （E=10.9 GPa）. Effects of the methyl group introduction and the TEOS vapor treatment on the structural stability and hydrophobicity have been studied.