基于环氧基POSS改性的低介电纳米多孔复合材料:微观结构对介电性能的影响

Low dielectric nanoporous composites based on epoxy-based POSS modification:Effect of microstructure on dielectric properties

随着超大规模集成电路的迅速发展,微型集成化高密度半导体元件迫切需要低介电材料。本文合成了具有笼型结构的环氧基倍半硅氧烷(EOVS),并与环氧树脂E51共混得到纳米多孔EOVS/E51复合材料。改性后,EOVS在E51基体中均匀分散。随着EOVS的增多,其笼型结构引入的纳米孔隙使EOVS/E51复合材料的自由体积增大,单位体积内极化分子的密度降低,EOVS含量为15wt%时,介电常数由4.21下降至2.51(1 MHz)。但是,EOVS上的环氧基团提供了新的反应位点,EOVS/E51复合体系的交联密度随EOVS增多而增大,EOVS含量达20wt%时,复合材料的自由体积减小,介电常数转而增大。此外,EOVS中Si-O-Si键的疏水性使复合材料的耐湿性增强,而无机骨架的热稳定性及纳米增韧效应导致复合材料的耐热性和抗冲性能明显提升,在微电子领域应用前景广阔。

With the rapid development of ultra-large-scale integrated circuits,micro-integrated high-density semiconductor components urgently require low dielectric materials.In this work,epoxy sesquisiloxane(EOVS)with cage structure was synthesized and blended with epoxy resin E51 to obtain the nanoporous EOVS/E51composite.As shown by SEM,EOVS nanoparticles are uniformly dispersed in the E51 matrix.With the increase of EOVS,the nanopores introduced by its cage structure make the free volume of EOVS/E51 composite increase and the density of polarized molecules per unit volume decrease,so that the dielectric constant decreases from 4.21 to 2.51(1 MHz)when the EOVS content is 15wt%.However,the epoxy groups on EOVS provide new reaction sites,so the crosslink density of the EOVS/E51 composite system increases with the increase of EOVS,and the free volume of the composite decreases and the dielectric constant turns to increase when the EOVS content reaches 20wt%.In addition,the hydrophobicity of the Si-O-Si bond of EOVS enhances the moisture resistance of EOVS/E51 composites,while the thermal stability of the inorganic backbone and the nano-toughening effect lead to a significant increase in the heat and impact resistance of the composite,which is promising for applications in microelectronics.