Crystallinity control of zeolite nanoparticles for the preparation of mesoporous low-k films through a fast hydrothermal process

A fast hydrothermal process for making coating solution containing MFI-type zeolite nanoparticles for the preparation of the mesoporous low-k films has been developed. The ratio of optical density (or particle crystallinity) of the nanoparticles in the films is a key factor influencing the electronic and mechanical properties. As the ratio is higher than 10%, the cracks are formed in the films, causing the decrease of the mechanical strength and the increase of the k values. Therefore, the ratio should be controlled less than 10% by using short hydrothermal time (less than 48 h). With the ratio of <10%, the films prepared from the coating solutions with the hydrothermal times of 36 and 42 h possess k values of less than 2, hardness of >1 GPa, elastic modulus of >10 GPa, and leakage current densities in the order of 10−8 A/cm2, those all reach the requirements for the application in the future integrated circuits.

► A fast hydrothermal process was used for preparing coating solutions for low-k films.
► The solutions contain MFI-type zeolite nanoparticles and a non-ionic surfactant.
► Ratio of optical density of coating solution has been defined in this paper.
► The smaller the ratio is, the poorer the particle crystallinity is in the solution.
► As the ratio < 10%, ultra-low-k film with high mechanical strength can be prepared.