METHOD FOR CONTROLLING CHEMICAL-MECHANICAL POLISHING AMOUNT BY MONITORING AMPLITUDE VARIED AMOUNT OF LASER REFLECTION LIGHT TO WAFER

摘要

PURPOSE: A method for controlling a chemical-mechanical polishing amount by monitoring an amplitude varied amount of a laser reflection light to a wafer is provided to control the amount of CMP(Chemical Mechanical Polishing) by using a variation of amplitude of a laser reflection light. CONSTITUTION: An optical detector outputs a converted electric signal(S) and a processing time(T) of a CMP process to a control system. The control system monitors the converted electric signal(S) and the processing time(T)(S10). The monitoring process is performed until the amplitude of the converted electric signal(S) becomes a final peak value(S12). A varied ratio of the converted electric signal(S) to time is compared with a predetermined threshold value(S14). A value of the converted electric signal(S) is decided as the peak value(Sp) when the varied ratio of the converted electric signal(S) to time is smaller than the predetermined threshold value(S16). A difference(S-Sp) between the peak value(Sp) and a current converted signal value is compared with a predetermined value(A1)(S18).