STRUCTURING OF POLYIMIDE-METAL CARBIDE LAYER SYSTEMS BY EXCIMER-LASERABLATION

Laser microlithography has been one of the most rapidly developing lit hographic methods in the last years. The possibility of using thin met al carbide layers deposited on polyimide coated substrates has been in vestigated. The deposition conditions of thin polyimide(less than or e qual to 1 mu m) and carbide (40 nm) films for lithographic application s were determined. UV laser ablation of the metal carbide layers was p erformed at different wavelengths. Ablation threshold fluences are aro und 20-90 mJ/cm(2). Clean ablation with high edge definition by one si ngle laser pulse is achieved at about 40-200 mJ/cm(2) leaving a smooth polyimide surface. At 248 nm ablation using two different pulse durat ions (32, 81 ns) was performed, but no significant differences could b e found. Microstructures can be produced by ablation using mask imagin g techniques. These results demonstrate the applicability of polyimide -metal carbide layer combinations as lithographic systems for a full d ry process: laser-ablation-structuring of the carbide image layer and subsequent image transfer by reactive ion etching of the polyimide.