Alternating PSM defect printability at 193-nm wavelength

Using alternating phase shifted-mask is an important way to enhance resolution and process window. In this article, the printability of defects of 193 nm alternating phase-shifted mask is reported. We built alternating phase-shifted masks with programmed defects of various types and sizes, and evaluated the impact of each defect on wafer CD. The masks include chrome and phase defects of various phase angles, with defect size down to 10 nm (at 1X size). The Maximum Non-Printable Defect (MNPD) is defined as the maximum defect size that distorts wafer CD less than 10 percent. MNPD of various types of defects were compared on printed wafers for lines and spaces patterns with nominal line width down to 70 nm. A model was created to simulate, further analyze and correlate the experimental results. The simulation also allows for extension beyond the experiment parameter space.