Patent ID: 6437330
Filing Date: 2002-08-20
Classification: H01J

Abstract:
A method of adjusting a charged particle beam of a beam optical system for obtaining an observational image of a sample surface by scanning a charged particle beam to detect secondary charged particles given off from the sample surface, comprising:displaying at least three images of the sample surface, a first image scanned from an initial adjusting value, a second image scanned from the initial adjusting value +&Dgr;, and a third image scanned from the initial adjusting value âˆ’&Dgr;, wherein &Dgr; is a known predetermined value; selecting a clearest image from among the at least three images of the sample surface; varying the beam optical system so that the initial adjusting value is that of the clearest image; decreasing &Dgr; to a smaller value; and repeating the above steps of adjusting the charged particle beam of the beam optical system until an optimal image is obtained.