METHOD FOR MEASURING THE THICKNESS OF A FILM USING A LASER CAPABLE OF MEASURING THE THICKNESS OF THE FILM THROUGH INTERFERENCE SIGNAL MEASURMENT OF A LASER BEAM WHICH IS REFLECTED BY RADIATING THE LASER BEAM TO THE FILM HAVING FINE THICKNESS

摘要

PURPOSE: A method for measuring the thickness of a film using a laser is provided to control a thickness measuring unit of the film with a fine unit instead of a half wavelength of a laser beam.;CONSTITUTION: A method for measuring the thickness of a film using a laser is as in the following. An irradiation unit irradiates a laser beam of a single wavelength to the film. A part of the laser beam passes through a spectrum unit and is focused and is reflected after being irradiated to the film. A part of the laser beam is reflected to a mirror after being reflected on the spectrum unit. The laser beam which is reflected on the film and the laser beam which is reflected on the mirror are sensed and an interference signal generated by path difference is measured. The laser beam of the single wavelength which is irradiated from the irradiation unit is irradiated to a workbench (500). A part of the laser beam passes through the spectrum unit and is focused and is reflected after being irradiated to the workbench and a part of the laser beam is reflected on the mirror after being reflected on the spectrum unit. The laser beam which is reflected on the workbench and the laser beam which is reflected on the mirror are sensed and an interference signal generated by the path difference is measured. A position path which is separated as a same distance based on the position corresponding to a maximum value of each interference signal measured by irradiating the laser beam to the workbench and the film is selected and the corresponding interference signal is selected. Phase difference of the interference signal is produced in preparation for the interference signal at the selected position path.;COPYRIGHT KIPO 2013