PURPOSE: To accurately plot by measuring a height of an alignment mark and a chip, and correcting an alignment correction coefficient based on an obtained step difference.
CONSTITUTION: A height between A-A' of a sample 101 is measured by using a laser light, maximum and minimum values of data are obtained, and set as a slice level to an average value. Then, average of data of larger values than the slice level is calculated as a height of a chip. Similarly, an average value of data of the level or lower is used as a height of a scribing area 103, and a difference between both is regarded as a step difference (h). Then, alignment marks 104 on the wafer are sequentially detected to obtain an alignment coefficient, and a height of the area 103 is measured. At the time of plotting, sum of the height of the area 103 and the difference (h) is used as a height of a plotting surface, and plotting is performed. Since the position of the mark and the actual position of the plotting surface are corrected, accurate plotting is performed.
IWASAKI TERUO
ANDO HIROZUMI
