Investigation on Aerosol Jet Etching for Thin Film Patterning

Abstract

As the critical dimension of the semiconductor memory device keeps shrinking, new etching method is required to etch nanometer-scale patterned thin film. Accordingly, we propose novel etching method called aerosol jet etching. This etching technique is to use an aerosol jet containing tiny liquid droplets which are made of an etchant. Liquid droplets are generated and accelerated onto the thin film by nozzle expansion into a vacuum chamber where the substrates are located. This method is intended to perform vertical anisotropic etching without redeposition by combining the chemical mechanism of wet etching and physical bombardment of particles in dry etching. Formation of nanometer-scale patterns by nanoetching process of thin films should be developed for the future semiconductor memory devices. Therefore, this new etching technique can be a prospective etching method. Also, this technique can be applied to nano-device, MEMS and various thin-film sensors. In this study, we have investigated the etch characteristics of nanometer-scale patterned thin films using aerosol jets which contain the tiny droplets of proper liquid etchants. We designed and optimized etching equiment for aerosol jet etching, and proceeded the characterization and development of nanometer-scale patterns by using it. As the major experimental parameters, there are the nozzle geometry (nozzle shape and nozzle diameter), nozzle to substrate distance, chamber pressure, and substrate temperature. The etch rates were obtained by the surface profilometer and field emission scanning electron microscopy (FESEM) and etch profiles were observed by FESEM. In addition, X-ray photoelectron spectroscopy were used for the investigation on the etched surfaces for the etch mechanism. Acknowldgments This work was supported by NRF-2017R1D1A1B03033143