1. A method of inspecting a semiconductor device, the method comprising: obtaining inspection image data of an inspection pattern of an inspection layer on a substrate; extracting inspection contour data including an inspection pattern contour from the inspection image data by an electronic system; merging the inspection contour data with comparison contour data of a comparison layer to obtain merged data, the comparison layer overlapping the inspection layer; and determining a horizontal distance between the inspection pattern contour and a comparison pattern contour of the comparison contour data based on the merged data.