Patent ID: 6781141
Filing Date: 2004-08-24
Classification: H01J

Abstract:
A method of detecting and measuring noise and resonance in an electron beam tool, comprising the steps of:providing a spectrum analyzer with ability to look at different components of noise, said analyzer having a previously charted noise frequency grid position; deflecting as least one electron beam; calibrating said deflected electron beam at least in a fine and a coarse mode by scanning said beam over a grid-like calibration target; storing position of said beam in each instance; using said spectrum analyzer, analyzing the position of where the beam is each time it is detected in relation to where it is supposed to be according to the previously charted positions; concluding presence of noise and its measurement according to result of said analysis performed by said spectrum analyzer; and providing a calibrating sequence for each beam present based on conclusions made in said concluding step and said analyzing step.