Characterization of low-k benzocyclobutene dielectric thin film

This paper reports the characterization of a photosensitive benzocyclobutene (BCB), a low dielectric constant spin-on polymer for use as interlayer dielectric in the microelectronics industry. Research work is divided into three main sections. First, BCB thin film characterization was done to investigate the effects of curing conditions on BCB film thickness, dielectric properties, optical properties and extent of cure. Thermal stability of BCB was then evaluated using thermogravimetric analysis (TGA) to detect weight loss during thermal curing and degradation. Finally, curing kinetics study was conducted using both differential scanning calorimetry (DSC) dynamic (American Society for Testing and Materials method) and isothermal approaches. The first study shows that determination of vitrification point during thermal curing of BCB is crucial to predict film properties. By curing to just before vitrification, lowest refractive index, hence dielectric constant, could be obtained.