Chromeless phase lithography (CPL) has been shown as a viable technology for 65nm technology node. Unlike alternating PSM, the CPL aerial image is formed by the interference from a pair of symmetrical phase edges. It is thus less vulnerable to mask phase errors and to the mask defect types that are otherwise highly sensitive to asymmetrical phase imaging. Among the various types of mask defects, the quartz bump has been singled out as the phase defects that must be captured and repaired during the CPL mask manufacturing. In this paper, we focus on the CPL mask inspection and repair technologies for the quartz bump defect. Using a set of programmed CPL mask defects, we characterize the quartz defect inspectablity and repair capability. We then use AFM and SEM tools to scan the defect for the precise location and dimension. The FIB induced etching process, gas assist etching (GAE), are used for the quartz bump repair. In order to better control the repairing effect, a multi-pass GAE process was proposed. The defect repair performances were verified by AIMS and resist printing. We show that the quartz bump can be detected using the current state-of-the-art mask inspection tool and most importantly, it can be repaired effectively with minimum or little impact to the printing performance.
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