METHOD AND APPARATUS TO DETECT END POINT OF SURFACE POLISHING PROCESS OF SEMICONDUCTOR WAFER

摘要

PURPOSE: A method and an apparatus for detecting an end point of a surface polishing process of a semiconductor wafer are provided to detect correctly the end point by using an interference phenomenon of light. CONSTITUTION: A white beam is irradiated on a surface of a wafer in order to measure a spectral interference signal(S1). A beam-compensated spectral interference signal is extracted by performing a comparing process(S2). A beam-compensated noise-erased spectral interference signal is extracted by a logic process(S3). A wavelength value for a particular reference point of a beam-compensated noise-erased spectral interference signal waveform is extracted(S4). A thickness change value of the particular reference point is calculated(S5). The first branch process is performed if the thickness change value does not approach a thickness value of a tracking start point(S6). A wavelength value of the particular reference point of the beam-compensated noise-erased spectral interference signal waveform is detected if the thickness change value approaches the thickness value of the tracking start point(S7). The second branch process is performed if the wavelength value does not approach a wavelength value of a tracking end pint(S8). An end point is detected and a wafer polishing process is finished if the wavelength value approach the wavelength value of the tracking end pint(S9).