Abstract: A method and apparatus for detecting material accretion and peeling in a system such as a plasma process chamber, including multiple optical sensors which are provided in the chamber above a gas distribution plate or other surface inside the chamber. The optical sensors are connected to a central process controller that is capable of terminating operation of the chamber and may be equipped with an alarm. In the event that the optical sensors detect asymmetries in brightness or light reflection among various portions or regions of the gas distribution plate or other surface, which asymmetries may indicate the formation of a material coating on the plate or dislodging of contaminant particles from the plate, a signal is sent to the process controller, which may be adapted to terminate the plasma process, alert operating personnel, or both.

Abstract: A cassette pod stage that is equipped with locked guide pins is described. The cassette pod stage of the present invention is provided with at least one aperture therethrough for engaging at least one guide pin. The guide pin is provided with a top portion, a bottom portion and a skirt portion in-between the top portion and the bottom portion for use as a stop during installation of the guide pin through an aperture in the cassette pod stage. The bottom portion of the guide pin is provided with a threaded portion for engaging a locking nut after the guide pin is installed with the threaded portion extending beyond the bottom surface of the cassette pod stage for such engagement.

Abstract: A method and apparatus for detecting material accretion and peeling in a system such as a plasma process chamber, including multiple optical sensors which are provided in the chamber above a gas distribution plate or other surface inside the chamber. The optical sensors are connected to a central process controller that is capable of terminating operation of the chamber and may be equipped with an alarm. In the event that the optical sensors detect asymmetries in brightness or light reflection among various portions or regions of the gas distribution plate or other surface, which asymmetries may indicate the formation of a material coating on the plate or dislodging of contaminant particles from the plate, a signal is sent to the process controller, which may be adapted to terminate the plasma process, alert operating personnel, or both.