低介电常数含氟氧化硅薄膜的红外光谱分析

用等离子体化学气相淀积 (PECVD)制备了含氟氧化硅薄膜 (Si OF薄膜 )。通过傅里叶变换红外光谱 (FTIR)分析 ,研究了氟掺入后薄膜结构的变化 ,并进一步讨论了氟对薄膜介电常数及吸水性的影响。研究表明氟掺入后改变了 Si- O键上的电荷分布 ,降低了薄膜中 Si- O键的极性 ,导致 Si- O键伸缩振动吸收峰发生蓝移。同时氟的掺入抑制了强极性 Si- OH键的形成。这些变化有利于薄膜中离子极化和偶极子转向极化的降低 ,因而使薄膜介电常数减小。对 Si- F吸收峰的高斯拟合表明 ,在氟含量较高时 ,薄膜中掺入的氟一部分会以 Si F2 结构存在。由于 Si F2 结构稳定性较差 ,易与水汽发生作用 ,因而高氟掺杂的 Si OF薄膜易吸水 ,并使薄膜性能变差

FTIR Analyses of SiOF Thin Film with Low Dielectric Constant

SiOF thin films with low dielectric constant were deposited using TEOS/O 2/SiF 4 mixtures in a plasma enhanced chemical vapor deposition system. Through the FTIR (Fourier Transform Infrared Spectrometry) analyses, the changes in chemical structure of SiOF film are studied, Further more, the dependence of dielectric constant and water resistibility of thin film on the chemical structure after F doping is also discussed. It is found that the incorporation of F atoms change the partial charge of atoms in Si O band, and the polarity of Si O bond is reduced. The Si OH bonds with high polarity also decrease as a result of F doping. These changes in structure contribute to the decrease of the dielectric constant of SiOF film. In addition, it is found that SiOF films with high F content comprise SiF 2 structures, which are easy to react with water to degenerate SiOF thin fims.