Technological challenges in implementation of alternating Phase Shift Mask

Alternating Phase Shift Mask (APSM) reticles is critical to achieve sub 0.1 um poly gate lithography. Intrinsic APSM image inbalance can be resolved with various methods such as isotropic etch and aperture sizing, where positional line-shift can be reduced to within 5nm of final CD target. Defect reduction of APSM fabrication is addressed with multiple-option strategy to achieve high manufacturing yield. After Develop Inspection (ADI) capability was demonstrated with partial and complete missing 180 deg apertures, detected at post-develop with correlation to Qz defect after dry etch. Feasibility of APSM inspection and repair was demonstrated with existing toolsets and critical gap versus APSM defect specification remained to be bridged.