METHOD AND SYSTEM FOR FOCUSING CHARGED PARTICLE BEAM

PROBLEM TO BE SOLVED: To provide an efficient method for determining a focus error. SOLUTION: This method is used for focusing a charged particle beam. The method comprises: (a) a step for changing a focal point of the charged particle beam according to a first focal point pattern, scanning a first zone of a sample, and, at the same time, collecting a first set of detection signals; (b) a step 330 for changing a focal point of the charged particle beam according to a second focal point pattern, scanning a second zone ideally identical with the first zone, and, at the same time, collecting a second set of detection signals; and (c) a step 340 for processing the first and second sets of detection signals to determine a focal point characteristic. The first focal point pattern and the second focal point pattern are different depending on the location of the optimum focal point. COPYRIGHT: (C)2006,JPO&NCIPI