Thermo-curable and photo-patternable polysiloxanes and polycarbosiloxanes by a facile Piers–Rubinsztajn polycondensation and post-modification

Abstract

With the rapid development of integrated circuit (IC) chips towards nanometric miniaturization, advanced integration and high performance, interlayer dielectric (ILD) materials play an increasingly important role in meeting the requirements of various advanced packaging technologies. Herein, a series of benzocyclobutene (BCB)-functionalized thermosetting polysiloxane and polycarbosiloxane ILD materials are disclosed. The main-chain structure was achieved and modulated by an efficient Piers–Rubinsztajn (P–R) polycondensation, and the post-modification of thermo-curable BCB groups was realized via a simple Heck reaction. The fully cured resins exhibited excellent dielectric properties with a dielectric constant (D_k) of 2.43 and a dissipation factor (D_f) of 1.18 × 10⁻³, good thermal stability with the 5% weight loss temperature (T_d5) above 450 °C, tunable mechanical properties, and low water absorption (0.13% in boiling water for 24 h). In addition, the resultant polysiloxane and polycarbosiloxanes showed the great capability of convenient photolithography with a bis-diazirine cross-linker under UV light. Compared with traditional BCB-functionalized thermosetting ILD resins, our procedure avoids laborious synthesis and subtle pre-polymerization control of BCB monomers. It provides a facile and universal method for modulating the dielectric and mechanical properties of ILD materials, showing great potential in the advanced packaging of ICs, flexible displays and printed circuit boards (PCBs).