Patent ID: 7076920
Filing Date: 2006-07-18
Classification: H01L,Y10S

Abstract:
1. A method of automatically controlling a load lock that facilitates transfer of parts between a room at ambient atmospheric pressure and a vacuum transfer or processing chamber maintained at a pressure less than one torr and that has an evacuatable load lock chamber, an exterior door positioned between the load lock chamber and the room, a interior door positioned between the load lock chamber and the transfer or processing chamber, a exterior door actuator that is responsive to an exterior door control signal to open or close the exterior door, an interior door actuator that is responsive to an interior door control signal to open or close the interior door, and a vacuum pump connected to the load lock chamber for evacuating the load lock chamber, comprising: providing a modular differential and absolute pressure transducer that includes a housing, which contains a pirani pressure sensor, a differential pressure sensor, and a control circuit, with both of the sensors being in fluid flow relation to a manifold and the pirani pressure sensor being capable of measuring absolute pressure at least in a range of 100 torr to 10 connecting the pressure transducer via one fluid flow connection of the manifold to the load lock chamber to expose both said pirani pressure sensor and said differential pressure sensor to pressure in the load lock chamber via said one fluid flow connection so that said modular differential and absolute pressure transducer senses and transduces said pressure in the load lock chamber to a first voltage that is indicative of the pressure in the load lock chamber and senses and transduces a differential pressure between the pressure in the load lock chamber and the ambient atmospheric pressure to a second voltage that is indicative of the differential pressure between the pressure of the load lock chamber and the ambient atmospheric pressure, whereby said modular differential and absolute pressure transducer also outputs the interior door control signal when the first voltage equals an interior door control reference voltage and outputs the exterior door control signal when the second voltage equals an exterior door control reference voltage; setting the interior door control reference voltage of the modular differential and absolute pressure transducer to a level that equals a voltage that is indicative of the pressure in the load lock chamber when the load lock chamber is evacuated to a pressure at which the interior door is to be opened; setting the exterior door control reference voltage of the modular differential and absolute pressure transducer to a level that equals a voltage that is indicative of the differential pressure between the pressure of the load lock chamber and the ambient atmospheric pressure at which the exterior door is to be opened; connecting an interior door control link between the modular differential and absolute pressure transducer and the interior door actuator and connecting an exterior door control link between the modular differential and absolute pressure transducer and the exterior door actuator; and powering the circuitry in the modular differential and absolute pressure transducer to produce the interior door control signal and the exterior door control signal in sequence as the load lock chamber is evacuated and then re-filled with gas such that the modular differential and absolute pressure transducer: (i) provides the interior door control signal to the interior door actuator via the interior door control link to open the interior door; and (ii) provides the exterior door control signal to the exterior door actuator via the exterior door control link to open the exterior door.