Rapid thermal curing of BCB dielectric

The authors demonstrate the feasibility of rapid thermal curing (RTC) of benzocyclobutene (BCB) thin films using an infrared belt furnace. The effects on film properties resulting from a dramatic reduction in cure time (5 h to 5 min) are summarized. The extent of cure was determined by FTIR (Fourier-transform infrared spectroscopy) and was subsequently modeled as a function of reaction kinetics using the measured temperature profiles. FTIR spectra from the RTC films were identical to those obtained using a conventional inert gas oven and a convectively heated belt furnace, indicating that: (1) the polymerization mechanisms and the resulting polymer network structure are identical, and (2) no chemical enhancement of the curing occurs due to the absorption of infrared radiation. There are no statistically significant differences in the resulting stress and adhesion properties for samples cured by the RTC process vs. the conventional process for film thicknesses ranging from 1 to 24 μm. Planarization measurements, made on isolated features up to 100 μm in width, also indicate no differences in the cured films