Patent ID: 6586736
Filing Date: 2003-07-01
Classification: H01J

Abstract:
A method of controlling charge build up on a sample while an image is being generated of a portion of the sample with a measurement device having a source unit for directing an electron beam substantially towards the sample, a detector for detecting particles that are emitted from the sample, an electrode proximal to the sample having a hole through which the electron beam and a portion of the emitted particles may pass, and an image generator for generating the image of the sample from the detected particles, the method comprising:applying a first voltage to the electrode when the electron beam is substantially in a center of the hole, the first voltage being selected to control positive charge build up on the sample; and applying a second voltage to the electrode when the electron beam is deflected a predetermined distance from the center of the hole, the second voltage being selected to allow a significant amount of emitted particles to reach the detector to facilitate image generation.