| 摘要 |
PURPOSE:To detect reference point for irradiation and beam diameter from change of secondary electron emission ratio by forming a square hole having the wall surface inclined in the scanning direction of ion beam to a multilayer semiconductor substrate. CONSTITUTION:When a square hole 7 having inclined wall surface is provided to the edge part of substrate 1 and it is scanned by the focused ion beam 6, intensity of secondary electrons 9 emitted from the GaAlAs layer 3 and GaAs layer 4 is different. A particular point, for example, the corner of square hole 7 is determined to the reference point of beam irradiation by measuring 10 intensity of secondary electrons and detecting a change of output signal of intensity by the secondary electron emission ratio from etaa to etab. A beam diameter can be measured from a product of a time when the signal etaa changes to etab, namely the time when the beam 6 has passed the boundary 8 of the different kinds of junction surfaces and a scanning speed. According to this constitution a beam diameter can be measured on the real time basis for each irradiation and accurate ion beam can be realized. |
