Achieving Hydrophobic Ultralow Dielectric Constant Polyimide Composites: Combined Efforts of Fluorination and Porous Fillers

The advancement of the microelectronics industry necessitates the use of interlayer insulation materials with low dielectric constants and high mechanical properties. In this paper, a new type of copolymerized fluorinated polyimide (PI) is synthesized, and mixed with polyhedral oligomeric silsesquioxane (POSS) functionalized mesoporous silica (MCM-41@POSS). The PI/MCM-41@POSS composites exhibit good hydrophobicity. With the addition of 3 wt% MCM-41@POSS, the PI composite attained an ultralow dielectric constant (k = 1.88) and low dielectric loss (0.01) at 1 MHz, which is attributed to the mesoporous structure of MCM-41 and the restriction of polarization in the bonded region. The decorated POSS effectively prevents the penetration of PI molecular chains into the mesopores of MCM-41. In addition, the PI composites containing 3 wt% of MCM-41@POSS obtain the highest maximum stress of 104.03 MPa with an elongation at break of 13.73%. The hydrophobic PI composites with ultralow-k are expected to be good candidates as interlayer materials in microelectronics devices.