Patent ID: 7145653

Claim:
A system that monitors and controls a contaminated particle count in a chamber during a photoresist coating and a development process, comprising: a plurality of lasers that are positioned at different heights in the chamber with respect to a surface of a substrate, the plurality of lasers respectively transmit light across the chamber and through an aerosol that resides proximate the substrate, respective light transmissions are attenuated by contaminated particles in the aerosol; a plurality of detectors that are positioned to receive attenuated light from respective light transmission paths and that provide respective signals that are indicative of a light intensity associated with the received attenuated light; a measuring system that is coupled to the plurality of detectors, the measuring system converts the respective signals to digital data; a processor that is coupled to the measuring system, the processor analyzes the digital data and generates a control signal; and an exhaust controller that receives the control signal from the processor and automatically activates an exhaust fan to remove contaminated particles from the chamber when the contaminated particle count exceeds a predetermined threshold, the exhaust controller automatically activates the exhaust fan before, during and after photoresist coating and development.