MEASURING METHOD FOR DISTRIBUTION OF ELECTRON BEAM CURRENT DENSITY

摘要

PURPOSE:To make measurement under no influence of a noise by intermittently emitting an electron beam modulated by a blanking signal and then by extracting only the same frequency component as the blanking signal from the output of an electron beam detector by using a frequency analyzer. CONSTITUTION:To measure the current density distribution of electron-beam irradiation region 15, movable table 6 is driven first according to the program of information processor 11 to move detection part 5 into the irradiation region of electron beam 12 and deflection unit 4 is used to shift irradiation region 15 according to the steps sectioned in the direction of XY2. The order of this displacement allows the expansion or contraction of each unit section with the displacement in the direction of XY2 and the output of detector 5 at each position is processed by frequency analyzer 10 to extract only the amplitude value of the same frequency component as the blanking signal. Then, the extracted component amplitude value is processed to obtain the variation in beam current of each unit section, thereby forming the two-dimensional electron-beam current density distribution.