EXPOSURE DEVICE FOR ELECTRON BEAM

摘要

PURPOSE:To automatically and easily perform beam focusing and the removal of astigmatism by a method wherein the conductive currents of an objective lens and an astigmatic correcting coil are set at the best value for beam resolving power. CONSTITUTION:An electron detector 11 detecting reflective electrons obtained by irradiating electron beams at a target 10 being prepared by adhering fine grains 10b having high reflective electron detection rate is provided on a substrate 10a. An objective lens 9 and an astigmatic correction coil 8 measuring beam resolving power based on the detection signal in the detector 11 are provided. The conductive current of the lens 9 is variably controlled to obtain the optimum current value for the beam resolving power and the conductive current of the lens 9 is set at the value thus obtained. Similarly, the optimum current valve for the beam resolving power measured by variably controlling the coil 8 is set at the value thus obtained. In this way, beam focusing and the removal of astigmatism can automatically be performed.