Abstract: A wall deposit monitoring system for measuring variation in wall deposit thickness in an etch or deposition chamber having a contained reactive environment includes at least one quartz or other piezoelectric crystal sensor installed through a wall of the chamber using a feed-through member. A cover assembly retains the sensor at a projecting end of the feed-through member in a position in proximity with the interior of a chamber wall. The cover includes an opening providing access to the active portion of the sensor for exposure to the reactive environment. An attached oscillating device causes the active portion of the sensor to resonate. As processing is performed in the chamber, a solid reaction product accumulates on the exposed active portion, damping the vibration of the sensor. A detection device sensing the shift in frequency can then calculate the relative change in thickness for a given material.

Abstract: A multiple crystal head has aluminum rotary carousel within an aluminum body, and number of crystals disposed about the axis of the carousel. A water line coil is clamped to the aluminum body by a stainless steel clamp plate, and a beryllium copper finger spring provides thermal contact between the carousel and the body so that any heat from the deposition process is quickly removed by the water coil. A space is maintained between the front of the carousel and the proximal side of the body front face so that there is no scraping when the carousel rotates. A removable stainless steel heat shield over the body provides good thermal isolation and prevents deposits from reaching the aluminum body or other parts behind the shield. A pneumatic bellows and a pawl and ratchet assembly rotate the carousel to bring the various crystals into the active, monitoring position.