OPTIMIZATION OF AN ELECTRON-CYCLOTRON-RESONANCE ETCH PROCESS USING FULL WAFER CHARGE-COUPLED-DEVICE INTERFEROMETRY

Full wafer charge coupled device interferometry is a new technique tha t can be used for in situ monitoring of plasma etching. The use of thi s technique to optimize an electron cyclotron resonance etch process f or TaSiN and its application to x-ray mask fabrication are presented. Fine tuning of the etch process was performed by optimizing the microw ave power and the collimating magnet current. Under optimized conditio ns, etch rate uniformity (3 sigma) across a 4 in. substrate was as low as 2%. The full wafer interferometer enables in situ uniformity measu rements, thus minimizing process development time. The etch process ha s been used to successfully fabricate sub-0.25 mu m x-ray masks. (C) 1 997 American Vacuum Society.