Platinum Etching and Plasma Characteristics in RF Magnetron and Electron Cyclotron Resonance Plasmas

The properties of platinum etching were investigated using both rf magnetron and electron cyclotron resonance plasmas, together with measurement of the plasma parameters. Experiments were performed over a wide pressure range from 0.4 to 50 mTorr in Cl2plasmas. In rf magnetron plasmas, the etch rate of Pt was constant at the substrate temperature from 20 to 160°C. The etch rate and the plasma electron density increased with decreasing gas pressure from 50 to 5 mTorr. In ECR plasmas for rf power of 300 W, the etch rate of Pt was almost constant (?100 nm/min) with decreasing gas pressure from 5 to 0.4 mTorr, while the plasma electron density was gradually increased with decreasing gas pressure. These experimental results were discussed with respect to the relationship between the etch yield and ratio of neutral Cl flux and ion flux incident on the substrate. Submicron patterning (0.5 µm lines & spaces) of platinum masked with photoresist was demonstrated using Cl2plasmas in ECR discharges. High accuracy was obtained with no undercutting.