Fine pixel SEM image for EUV mask pattern 3D quality assurance based on lithography simulation

Optical proximity correction (OPC) is still an essential technology for critical dimension (CD) control in Extreme Ultra Violet (EUV) lithography. For quality assurance of EUV mask pattern, a metrology of complicated two-dimensional (2D) OPC patterns is important. Moreover, the side wall angle management of a mask pattern becomes important in EUV lithography because exposure light is diagonally incident on a mask pattern. The quality assurance of EUV mask pattern requires the pattern edge extraction including the side wall angle. We had developed an SEM which is one of the key factors of this three-dimensional (3D) quality assurance method. The high accuracy measurement of a side wall angle using Tilting and Moving Objective Lens (T-MOL) is most feature of this SEM. Employing this SEM, we will add the side wall angle information to the system for guaranteeing 2D OPC patterns before shipping the mask to a wafer factory. In this paper, we report the study about the management of the side wall angle of an EUV mask pattern. And then we report the evaluation results of the side wall angle measurement system with a tilted fine pixel SEM image that satisfies the requirement of the management.