Patent ID: 7494892

Claim:
A method of measuring warpage of a rear surface opposite to a crystal growth surface of a substrate using a laser displacement meter, said substrate being disposed on a substrate support table, comprising: a substrate detection step detecting a plurality of displacement values respectively corresponding to a plurality of measurement points on said rear surface of said substrate using said laser displacement meter; a noise removal step removing noise contained in said plurality of displacement values; an outer peripheral portion removal step calculating a plurality of displacement values for calculation by removing from said plurality of displacement values those respectively corresponding to the measurement points in an outer peripheral portion of said substrate; a smoothing step smoothing said plurality of displacement values for calculation to calculate a warped surface; a best fit plane calculation step calculating a best fit plane having the minimum distance to said warped surface; and a warpage calculation step calculating as warpage a sum of a distance from said best fit plane to a point represented by the greatest displacement value of said warped surface on one side with respect to said best fit plane and a distance from said best fit plane to a point represented by the greatest displacement value of said warped surface on the other side with respect to said best fit plane, wherein an optimization cycle including said smoothing step, said best fit plane calculation step, and said warpage calculation step is repeated one or more times, and at least one noise removal step is included in an interval between said repeated optimization cycles, or after said smoothing step in said optimization cycle.