Particles generated within a semiconductor wafer process chamber are monitored by emitting a rastered laser beam into the process chamber and detecting a two-dimensional image of scattered radiant energy within the process chamber. A video frame representing a matrix array of pixel intensities is produced...http://www.google.de/patents/US6115120?utm_source=gb-gplus-sharePatent US6115120 - System and method for detecting particles produced in a process chamber by scattering light
