A method includes: coupling a first end of a first conductive trace to a free electron source; scanning exposed surfaces of the first and a second conductive traces with an electron beam, the first conductive trace and a second conductive trace being alternately arranged and spaced apart; obtaining an image of the first conductive trace and the second conductive trace while performing the scanning; and determining a routing characteristic of the first conductive trace and the second conductive trace based on the image.