Postpolymerization of Functional Organosiloxanes: An Efficient Strategy for Preparation of Low‑<i>k</i> Material with Enhanced Thermostability and Mechanical Properties

A novel functional oligomer (<b>Si-TFVE</b>) with a siloxane backbone and thermally cross-linkable trifluorovinyl ether groups (−OCFCF<sub>2</sub>) is reported here. When postpolymerized at high temperature, <b>Si-TFVE</b> converts to an amorphous cross-linked network (<b>Si-PFCB</b>), which shows a dielectric constant of 2.33 and dielectric loss below 2.1 × 10<sup>–3</sup> at 30 MHz. <b>Si-PFCB</b> also shows excellent film uniformity with the surface roughness less than 5.79 nm over a 1 μm square area. Moreover, <b>Si-PFCB</b> shows high thermostability with a 5 wt % loss temperature of 472 °C and no obvious <i>T</i><sub>g</sub> below 350 °C. In regard to the mechanical properties, <b>Si-PFCB</b> has Young’s modulus, hardness, and bonding strength with silicon wafer surface of 10.06 GPa, 0.392, and 4.93 GPa, respectively. These results suggest that such oligomer is suitable for utilization in ultralarge scale integration circuits. In addition, this contribution provides a new route to prepare cross-linked organosiloxanes only by heating instead of using catalysts or initiators in the traditional procedures.