A 4K detector array for on-wafer extreme ultraviolet (EUV) imaging is first-time demonstrated. The proposed detector array features full FinFET CMOS logic compatibility, compact 1T pixel, high spatial resolution, and battery-less sensing. The in situ stored sensed signal can be accessed through offline nondestructive wafer-level tests. EUV images projected on wafers can be truthfully reflected by readout signals, providing in-tool monitoring of critical parameters in advanced lithographical systems for CMOS technologies beyond 5-nm node.