Overlay measurement device

The invention relates to an overlap measurement device. The present invention relates to an overlay measurement device, and more particularly, to an overlay measurement device capable of quickly measuring an overlay error between layers having a large height difference. The present invention provides an overlay measurement device for measuring an error between a first overlay mark and a second overlay mark which are paired and are respectively formed on different layers formed on a wafer, the overlay measurement device comprising an imaging system and a controller, the imaging system is configured to acquire an aligned image of a first overlay mark and a second overlay mark paired at a plurality of focal positions, and the controller is coupled in a manner communicable with the imaging system. The overlapping measurement device has the advantage of being capable of rapidly and accurately measuring the overlapping error between layers with large height difference. 本发明是有关于一种重叠测量装置。更详细而言是有关于一种可快速测量高度差较大的层之间的重叠误差