Method and apparatus for reading the wafer ID simultaneously

摘要

The present invention discloses apparatuses and methods for simultaneous viewing and reading top and bottom images from a workpiece. The present ID reader can comprise an enclosure covering a top and bottom section of the workpiece with optical elements to guide the light from the workpiece images to a camera. The optical element can be disposed to receive images from a high angle with respect to the surface of the workpiece. The present ID reader can further comprise a light source assembly to illuminate the image. The light source assembly can utilize a coaxial light path with the images, preferably for bright field illumination. The light source assembly can also utilize a non-coaxial light path, preferably for dark field illumination. In an embodiment, the simultaneous images reaching the camera are separate into two distinct images on two different sections of the camera. In another embodiment, the simultaneous images reaching the camera are superimposed into one image on the camera.