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High voltage scanning electron microscopy (HV-SEM) has recently been adopted as an on-device overlay metrology tool. However, the chip-manufacturing industry requests more advanced tools capable of low-distortion imaging and versatile measurement functionality for multi-layer processing. We developed a high voltage e-beam inspection (HV-EBI) tool for on-device overlay metrology that fills the abovementioned requirement. The HV-EBI tool has the capability of variable acceleration voltage in the range of 30kV to 50kV and wide field of view (FOV) imaging up to a maximum of 50μm with extremely low first-order distortion in the level of <0.01% and 0.1mrad and uniform in-plane beam perpendicularity. In this paper, we demonstrate the performance of on-device overlay measurement by using the proposed HV-EBI tool combined with enhanced die-to-database (D2DB) algorithm and image processor.

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