New identification system for individual wafer management

A conventional identification (ID) has many illegible parts; ID recognition is difficult in approximately 20% of all processes. In contrast, new IDs in the V-shaped notch were clearly recognized up to the final process. The results can be explained in terms of marking dot topography and choice of the marking location. First, for marking the beveled part in a V-shaped notch on a wafer, known as finer marking, the influence of any semiconductor processes in which a conventional ID on the surface has only limited readability is kept to a minimum. Second, a marking dot formed by conventional laser marking has a central depression due to the process of general heat distribution. In contrast, a marking dot formed by finer marking has a central peak protruding from the surface, which is more easily distinguished than a dot which has a central depression. A difference in contrast has a great influence on readability for identification in semiconductor processes.