QUANTUM CASCADE LASER TRACE-GAS DETECTION FOR IN-SITU MONITORING, PROCESS CONTROL, AND AUTOMATING END-POINT DETERMINATION OF CHAMBER CLEAN IN SEMICONDUCTOR MANUFACTURING

摘要

A process for in-situ monitoring, process control, and the determination of an endpoint state of a chamber clean during the semiconductor manufacturing process attaches a tunable quantum cascade laser (QCL) (20) to the processing chamber (22) or the foreline of a semiconductor fabrication tool to detect concentrations of process gases, by-product gases, and other gaseous compounds affecting the manufacturing process, and to determine when concentrations of clean or by-product gases fall below a predetermined threshold. The QLC detection system then sends an automated electronic signal to the semiconductor manufacturing control systems to automatically change gas flow and other process control settings, and to the clean gas mass flow controller to shut off the clean gas flow once the threshold concentration of the monitored compound within the chamber is reached, thereby allowing more rapid preparation of the chamber for the next processing cycle.