Paper PS-TuP5
The Etching Mechanism of Zinc Oxide Thin Films for Optoelectronics Device Application using Inductively Coupled Plasma

Tuesday, October 16, 2007, 6:00 pm, Room 4C

Zinc oxide (ZnO) exhibits an interesting combination of multifunctional properties, including optical, piezoelectric, and optoelectronic properties, and in thin film form ZnO films find immense applications in many electronic devices including sensors, transducers, and high frequency surface acoustic wave (SAW) devices. It has advantage relative to GaN because of its availability in bulk, single-crystal form, and wide bandgap energy of 3.4 eV, which makes it transparent to visible light. The excition binding energy is ~60 mV for ZnO, as compared to GaN, ~25meV; the higher excition binding energy enhances the luminescence efficiency of light emission. Research and development of ZnO have been rapidly accelerated to improve materials for the last decades. But, etch properties of ZnO have not established yet. Accordingly for many application optoelectronic devices, the etching mechanism of ZnO thin films during the etching process must be understood. However, few of etching mechanism was examined in our previous works and it can be hardly etched. So it is very important to improve the high etch rate, vertical etch profile, smooth etch surface, high mask selectivity and smooth sidewalls for developing ZnO thin films. In this study, we investigated etch characteristics of the ZnO thin films in the inductively coupled plasma system. The etching characteristics of ZnO thin films were investigated in terms of etch rates and selectivity as a function of additive gas mixing ratio. The plasmas were characterized by optical emission spectroscopy analysis and quadrupole mass spectrometer measurements. The chemical reaction on the surface of the etched ZnO thin film was investigated with X-ray photoelectron spectroscopy. Scanning electron microscopy was used to investigate the etching profile.