Abstract: A method and apparatus for securely clamping a substrate to an electrostatic chuck during processing of a substrate. The method generally includes the steps of forming an initial electrostatic clamping force between the electrostatic chuck and the substrate, modifying the initial electrostatic clamping force when an rf voltage is applied to the electrostatic chuck during processing, and restoring the initial electrostatic clamping force with an offset voltage applied to the electrostatic chuck. The present invention also includes an electrostatic chuck having at least one electrode and a dielectric on the surface of the electrode for supporting a substrate. A voltage source is coupled to the electrode for electrostatically clamping the substrate to the surface of the electrostatic chuck with an initial electrostatic force. An rf source is coupled to the electrode for applying rf voltage to the electrostatic chuck and causing a change in the initial electrostatic force.

Abstract: A device for controlling the level of light in an area or room. The device includes a sensor that detects whether the room is occupied, a light meter that detects the level of ambient light entering the room, and circuitry that controls the lights in the room in response to the sensor and light meter. The controlling circuitry increases the light level in the room when the room is occupied and the light meter senses that the ambient light level is not above a particular level. When the room is unoccupied for a brief period of time, the device increases or decreases the light level of the room by controlling lights accordingly, in response to the level of light sensed by the light meter. And finally, when the room is unoccupied for an extended period of time, the device turns power off to all the lights in the room.