| 摘要 |
Provided in the present invention is a laser machining apparatus with a height position detecting function, which can rapidly and accurately measure the top surface height of a workpiece such as a semiconductor wafer maintained on a chuck table. The laser machining apparatus comprises: a chuck table; a laser beam radiating unit with an objective condenser lens which concentratedly radiates laser beams to the workpiece maintained on the chuck table; an interference height position detecting unit which detects the top surface height position of the workpiece using both light reflected from the top surface of the workpiece maintained on the chuck table, and interference of reference light; a light converging point position adjusting unit which moves the objective condenser lens in a vertical direction to a maintenance surface of the chuck table; a control unit which controls the a light converging point position adjusting unit based on the top surface height position of the workpiece detected by the interference height position detecting unit; and a confocal optical height position detecting unit which detects the top surface height position of the workpiece maintained on the chuck table. The control unit sets a difference between the top surface height position of the workpiece detected by the confocal optical height position detecting unit, as a correction value, and controls the light converging point position adjusting unit based on a height position where the top height position of the workpiece detected by the interference height position detecting unit is corrected by the correction value. |
