High-throughput fabrication of zeolite thin films via ultrasonic nozzle spray deposition

Abstract

Zeolite thin films with ordered nanopores and a low dielectric constant can serve as an insulation layer in microelectronic devices. However, the absence of a high-throughput deposition technique is a major technical hurdle in the industrial-scale production of zeolite thin films. Herein, we report on a scalable method, ultrasonic nozzle spray deposition (UNSD), which addresses this issue. A high-frequency standing wave introduced by the ultrasonic nozzle produces uniform sized droplets of the cast suspensions at a scale of tens to hundreds of micrometers, which results in a uniform thin film following the removal of the solvent. In this paper, we focus on the deposition of thin films comprising pure-silica zeolite MFI on a silicon wafer substrate. We systematically investigated how the quality of the zeolite thin films is affected by the composition of the cast suspensions and UNSD operating parameters. We identified the UNSD operating window that allows for the fabrication of uniform dense zeolite thin films at thicknesses ranging from hundreds of nanometers to 3 μm. We determined that zeolite MFI thin films prepared using UNSD outperformed those fabricated using conventional spin-on deposition in terms of uniform film thickness, low leakage current, and high Young's modulus.