Etching Characteristics of Au Thin Films using Inductively Coupled Cf4/Cl2/Ar Plasma

Abstract

The etching of Au thin films has been performed in an inductively coupled CF4/Cl2/Ar plasma. The etch properties including etch rate and selectivity were examined as CF4 content adds from 0 to 30 % to Cl2/Ar plasma. The Cl2/(Cl2 + Ar) gas mixing ratio was fixed at 20%. Other parameters were fixed at an rf power of 700 W, a dc bias voltage of –150 V, a chamber pressure of 15 mTorr, and a substrate temperature of 30℃. The highest etch rate of the Au thin film was 370 nm/min at a 10 % additive CF4 into Cl2/Ar gas mixture. The surface reaction of the etched Au thin films was investigated using x-ray photoelectron spectroscopy (XPS) analysis. The XPS analysis shows that the intensities of Au peaks are changed, indicating that there is a chemical reaction between Cl and Au. Au-Cl is hard to remove on the surface because of its high melting point. However, etching products can be sputtered by Ar ion bombardment.