Abstract: An apparatus and method for use is described which permits real time monitoring of build-up of particulate contamination in a wafer processing chamber. The apparatus is capable of monitoring particle build up in regions of a processing chamber which are not accessible by traditional optical particle scanners. An accelerometer is fastened to a body in the chamber upon which particulates deposit. The body is subjected to vibrations and produces a vibration signal which is detected by the accelerometer. The signal is processed to form a frequency spectrum of vibration amplitudes. Frequencies in a selected band are directly proportional to the particulate build up on the body. The invention is applied to a wafer annealing tool with a rotatable platform wherein particles deposit on a support body under the wafer. The method and apparatus have been shown to be reliable and accurate as well as cost effective and easily implemented.