| 摘要 |
PURPOSE:To obtain uniform current density distribution by adjusting the alignment device based on the current density so calculated the current density in each area inside electron beam projection image through addition and subtraction of measured current value in plural area which shares a part of the boundary of the above area. CONSTITUTION:In order to obtain average current density at the rectangular area A inside the rectangular projection image 5-2, rectangular porous image 5-2 is projected on the aperture rectangular porous image 8-1 of the and adjustment is made by means of the electron beam deflector so that the projected position may be as shown in Fig. b. In this case, mcasurement is made of total current of beam passing holes: I1=IA+IB+IC+ID. In the same way, I2=IC+ID for Fig. c, I3=IC+ID for Fig. d and I4=IB+IC for Fig. e, enabling IA=I1+I2-I3-I4 to be calculated. Average current density can be obtained through division by the area of A. By repeating the same measurement and calculation, current density in a given area inside the projection image 5-2 can be obtained and its distribution is made uniform through the adjustment by the alignment device. |
