Nanomachining is one of the primary repair processes for leading-edge technology photomasks. Many hardware improvements have been made in successive nanomachining-tool generations to improve repair performance specifications (stability, drift, and z-depth control). However, improvement to the repair processes are still needed to address the use of the latest generation of high aspect-ratio (HAR) NanoBitsTM (1.8 AR and above). Although beneficial for repair of leading-edge photomasks, HAR NanoBitsTM exhibit greater degrees of nonlinear deflection, wear, and even breakage during traditional repair processes. In this work, the authors chronicle investigations into new nanomachining process options to enable subtractive hard defect repair with HAR NanoBitsTM down to the most advanced technology node with topographic z-depth control within ±0.5 nm and no detectable line edge, or multilayer capping layer, roughness.
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