Indium tin oxide etch characteristics using CxH2x+2(x=1,2,3)/Ar

Abstract

For the next generation display devices, dry etching technique for indium tin oxide (ITO) used as a transparent electrode is required to obtain a highly anisotropic etch profile, and to decrease the dimensional loss after the etching. For the dry etching of ITO, the easy dry cleaning of etch byproducts attached to the chamber wall during the dry etching is also important. In this study, by using novel hydrocarbon gases mixed with Ar, such as ethane (C2H6) and propane (C3H8), the dry etch characteristics and the etch residue cleaning process have been investigated using an inductively coupled plasma etcher, and the results were compared with the conventionally investigated methane (CH4)-based gases, such as CH4 and CH4/H2 mixed with Ar. The result showed that the hydrogen in CH4/H2 both decreased the ITO etch rate, and decreased the etch selectivity over photoresist (PR). By using hydrogen-less hydrocarbon gas having the alkane structure, such as CxH2x+2 (x = 2, 3), both the ITO etch rate and the etch selectivity were increased with the increase of carbon in the alkane structure; therefore, the highest etch rate was observed for C3H8. In addition, with the increase of x in the carbon of CxH2x+2, less dimensional loss, more anisotropic etch profile, and lower surface roughness could be observed. During the etching, etch residues containing C, In, Sn, O, and H were accumulated on the chamber wall due to the low volatility of the etch byproducts; however, the etch residues formed by all three hydrocarbon gases could be successfully dry cleaned using H2/Ar plasmas through the formation of InCxHy(x < y), COx, and SnHx.