On the damage behaviour of A1_2O_3 insulating layers in thin film systems for the fabrication of sputtered strain gauges

摘要

We report on ablation experiments of sputter deposited thin film systems of NiCr and A1_2O_3 for the fabrication of strain sensors. To ensure proper functionality of the electrical circuits, the metal film has to be selectively removed while damage in the A1_2O_3 films has to be avoided. Damage thresholds of the A1_2O_3 layer are investigated and damage mechanisms are discussed. Damage thresholds decrease with increasing number of scans until reaching a constant value. The processing window defined as the ratio of AI_2O_3 damage threshold and NiCr ablation threshold increases with increasing film thickness and number of scans.