Phase defect printability and actinic dark-field mask blank inspection capability analyses

Abstract

Phase defect printability and phase defect detection capability were investigated by exposure and inspection experiments, and simulation analysis. A new test mask with absorber line patterns and programmed phase defects with sizes much smaller than used in a previous work, was exposed using dipole illumination. Simulation results showed that printability of phase defects at the wafer level depended not only on defects' sizes and their locations, or on the line widths of the pattern structures to be printed, but also depended on the illumination conditions employed for pattern printing. Actinic inspection test was also conducted using the programmed phase defect arrays formed on the test mask. Selete's upgraded dark-field inspection tool was demonstrated to have its capability to detect a bump defect of 1.2 nm in height and 40 nm in width at a detection probability of 90 % or larger. An extendibility of the actinic dark-field inspection to beyond half-pitch 22 nm node was also confirmed.