Synthesis and characterization of pure-silica-zeolite Beta low-k thin films

A new reaction mixture with the addition of n-propyl alcohol into the all-silica TEAOH–TEOS–HF–H2O gel was presented for the first time to prepare continuous and compact pure-silica-zeolite (PSZ) Beta film on silicon wafer. n-Propyl alcohol was used to produce much homogeneous reaction mixture as well as accelerate the crystallization of Beta nanocrystals. In addition, by utilizing the secondary growth method the PSZ Beta film was much thinner (3.5 μm) and the synthesis time can further decrease to 36 h. X-ray diffraction, scanning electron microscopy, ICP–AES and ellipsometry were used to characterize the PSZ Beta film. After calcination the PSZ Beta film exhibited the ultra-low dielectric constant and dielectric loss of 2.07 and 0.096 at 1 MHz, and the elastic modulus and hardness of 45 and 1.8 GPa, respectively. The PSZ Beta film with ultra-low dielectric constant, high thermally and mechanically stability would make them very promising low dielectric constant materials as insulating films in microelectronic.