One of the key parameters necessary to assure the functionality of any integrated circuit is the Critical Dimension Uniformity (CDU). There are different contributors which impact the total CDU such as mask CD Uniformity, scanner and lens fingerprint, resist process, wafer topography, mask error enhancement factor (MEEF).
We provide unique solutions to measure and improve the CDU if it does not meet the target CD. With the ZEISS CDC system mask makers can significantly improve the CD Uniformity on masks by gently changing the local transmission of the mask with the help of a femtosecond laser. The fs-laser introduces small shade-in elements in the quartz. By varying the density of the shade-in elements locally the transmission can be changed over the mask with the target to improve CD Uniformity.