Recent Advances in Lithography and High Level Critical Dimension Metrology Needs for Lithography

To enable patterning of 65‐nm half pitch and smaller dimensions, optical projection lithography is being extended with 193‐nm wavelength using water immersion lenses. To enable this extension more complex masks and greater comprehension of variations in the lithography process are being integrated into the integrated circuit design process. Metrology will play a critical role in defining these lithography friendly design rules and practices. The effects of line edge and line width roughness are also becoming increasingly apparent in device performance, so metrology tools need to be modified to accurately measure these variations as well. Tools for measuring critical dimensions, including roughness, with high precision and for quantifying pattern fidelity will be critical to enable the extension of lithography to smaller dimensions.