Surface reaction effects on dry etching of IGZO thin films in N2/BCl3/Ar plasma

Abstract

We were experimented the etching process of indium gallium zinc oxide (IGZO) thin films in an inductively coupled plasma. The dry etching characteristics of the IGZO thin films was studied by varying the N2/BCl3/Ar gas mixing ratio, RF power, DC-bias voltage, and process pressure. We determined the optimized process conditions that were as follows: a RF power of 700W, a DC-bias voltage of −150V, and a process pressure of 15mTorr. The minimum etch rate of the IGZO thin film was 38.1nm/min in N2/BCl3/Ar=(3:10:10sccm) plasma, and the selectivities of IGZO for Al and TiN were 0.26 and 0.38, respectively. From XPS analyses, the chemical reactions on the IGZO thin films were explained. From AFM and FESEM images, we found the etch conditions for the smooth surface and vertical sidewall conditions.