| 摘要 |
PURPOSE:To preform the exposure of high accuracy, by detecting the sharpness of the change in the electron ray strength easily and accurately. CONSTITUTION:The current strength distribution value detected is A/D converted, memorized, and from the changing rate between the points a to j of the distribution waveform, the tangent TN1 to TN5 every section is operated and memorized. The information about the waveform having the peaks P1 to P4 can be obtained with the subtraction of memory. When this is displayed via the switch,the maximum width H of the peak P corresponds to the time length t of the courved part of the electron ray current distribution waveform, and this represents the sharpness of the change in the strength at the edge of the section of the electron ray in rectangular section. The excitation of the final stage lens is adjusted so that the half value W of the peak P is minimized. The peak point Q2 of the peak P1 shows the electron ray starting to scan the mark object. Thus, the sharpness of the change in the strength of electron ray is easily and accurately detected, allowing to perform highly accurate exposure. |
