A thermally cross-linkable molecule composed of bis(trifluoromethyl)benzene and benzocyclobutene units (F1) was successfully prepared. Heating F1 (>200 °C) gave a cured resin, which showed a dielectric constant (k) of 2.47 at 30 MHz and an average k value of less than 2.51 in a range of frequencies from 0.15 MHz to 30 MHz. Such low k values are comparable to other polymeric low-k materials. For comparison, a perfluorobenzene with benzocyclobutene groups (F2) was also synthesized. The cured F2 exhibited an average k value of 2.98, indicating that the introduction of a trifluoromethyl group into the backbone of the molecules can efficiently decrease the dielectric constant of the molecules. The cured F1 also exhibited high thermostability (T5 = 429 °C, weight residual = 47.7% at 1000 °C under N2). These results suggest that F1 is suitable for the utilization in ultra large scale integration circuits.
