System for compensating against wafer edge heat loss in rapid thermal processing

摘要

A method for compensating against wafer edge heat loss during rapid thermal processing is disclosed. A semiconductor wafer is exposed to radiant energy that is uniform across the entire wafer surface. The wafer is exposed by projecting a radiant energy image onto the edge of said semiconductor wafer while providing radiant energy rays directly to the wafer's surface. The radiant energy image comprises reflecting radiant energy rays that pass through a positionally adjustable object onto the edge of the wafer. The positionally adjustable object is optional and it is mounted between an optical lens and a radiant energy source or it is mounted between a reflector and each radiant energy source (A second optical lens is optional). The energy rays absorbed at the edge of the wafer contain more heat intensity than do the rays which are absorbed by the inner portion of the wafer, thus producing uniform heat across the entire wafer. The system may also have at least one radiant energy source suspended over the wafer, a reflector mounted behind each radiant energy source, a reflector mounted behind the positionally adjustable optical lens. The optical lens may be a concave lens having its concave surface facing either towards the reflector or towards the wafer. The radiant source uses a single heating lamp or multiple heating lamps having a heat emitting element affixed inside each heating lamp (each heating lamp may have a reflective coating directly behind a each affixed heat emitting element).