As the design rule becomes continuously smaller, the Hard OPC is being applied to pattern design in semiconductor
production. Controllability of hard OPCed pattern’s quality directly affects to the performance of the device and yields of
production. Critical Dimension Scanning Electron Microscopy (CD-SEM) is used to accurately confirm the Critical
Dimension (CD) quality of the photomask. CD-SEM makes the pattern’s shape image by using secondary electrons
information directly from the Mask surface and can measure CD values. Classically the purpose of CD-SEM
measurement was to get one dimensional CD values. However it is difficult to guarantee complex hard OPCed pattern’s
quality by using only one dimensional CD values because complexity of pattern design has been increased.
To confirm and control the quality of hard OPCed pattern, the quality of pattern fidelity must be measured
quantitatively. In order to overcome this difficulty we developed a new method to quantitatively evaluate the quality of
pattern fidelity using EPE (Edge Placement Error) distance from the overlay between Target Design GDS and SEM GDS
contour which is extracted from CD-SEM image. This paper represents how to define and analyze quantitatively the
quality of complex hard OPCed pattern.