| 主权项 |
1. A method of adjusting a stigmator in a charged particle beam apparatus, wherein the method comprises:
directing a charged particle beam onto a sample wherein the charged particle beam traverses a quadrupole field generated by energizing at least four field generators of the stigmator, acquiring first and second images of the sample at different field strengths of the quadrupole field while energizing the at least four field generators according to a first setting of a plurality of settings of the at least four field generators, acquiring third and fourth images of the sample at different field strengths of the quadrupole field while energizing the at least four field generators according to a second setting of a plurality of settings of the at least four field generators, determining a plurality of image displacements, wherein a first image displacement of the plurality of image displacements is determined based on the first and second images and wherein a second image displacement of the plurality of image displacements is determined based on the third and fourth images, determining an optimum setting of the at least four field generators based on the plurality of image displacements and the plurality of settings of the at least four field generators so that an image displacement between two images acquired while energizing the at least four field generators according to the optimum setting at field strengths differing from each other by 1% of a maximum excitation of the at least four field generators is less than a predetermined limit,wherein the optimum setting of the at least four field generators is determined by evaluating a mathematical formula, the only constituents of which are the plurality of image displacements, the plurality of settings and at least one of at least one constant and at least one parameter, wherein the at least one parameter is independent of the plurality of image displacements and independent of the plurality of settings. |
