Quantitative Voltage Contrast by Feedback-Controlled Magnetic Deflection in Scanning Electron Microscopes
Original Publication Date: 1988-Feb-01
Included in the Prior Art Database: 2005-Feb-14
A technique is described whereby the energy of secondary electrons in a scanning electron microscope is measured using a magnetic analyzer. A null detector and a feedback loop is used so that the analyzer can be made sensitive to small voltage changes. In prior art, small voltage changes, using voltage contrast in scanning electron microscopes, were difficult to measure. The use of conventional retarding field spectrometers have had some success; however, because of the small signal level, noise and systematic errors introduced by fluctuations in the primary beam intensity have caused intrinsic problems. The concept described herein provides a way of reducing the noise problem and completely eliminating the systematic error problem.