Improvement of EUVL mask structure with black border of etched multilayer

For EUVL mask with thinner absorber, it is necessary to make black border area in order to suppress the leakage of the EUV light from the adjacent exposure shots Black border of etched multilayer is promising structure in terms of light-shield capability and mask process simplicity. However, EUVL masks with this structure do not have electrical conductivity between the inside and the outside of black border. Inspection area including device patterns belongs to the inside of the black border. In case that quality check for EUVL masks is performed with E-beam inspection, the area is floating. As a result, electrification to mask pattern occurs and causes degradation of E-beam inspection accuracy when the mask is inspected by E-beam inspection tool. In this paper, we refine EUVL mask structure with black border of etched multilayer in order to improve electrical conductivity. We will show evaluation results of E-beam inspection accuracy, and discuss specifications of electrically conductive black border area.