X-RAY MASK INSPECTION USING REPLICATED RESIST PATTERNS

A new X-ray mask inspection method using replicated resist patterns is proposed. It is able to detect fatal opaque defects on the back surface of the mask and at the bottom of the hole pattern, in addition to those on the front surface. It can also ignore transparent defects on the mask. This method is useful even for defect detection on a single-die mask through die-to-die comparison. For the false process defects occurring during the replication process, a discrimination procedure using a 2-step die-to-die comparison is proposed. In inspection tests with SEMSpec, we investigate the relation between the detection sensitivity to small resist defects and the conductive-coating thickness on them.