Patent ID: 7683317

Claim:
A method for detecting hidden defects, the method comprising the stages of: receiving an object that comprises an opaque layer positioned above an intermediate layer; defining an energy band in response to at least one characteristic of the opaque layer and at least one characteristic of a scanning electron microscope, wherein the energy band defines a spectral range of energy levels of secondary electrons; adjusting a voltage supplied to an input grid of a spectrometer such that secondary electrons with energy levels within the spectral range of the energy band are accepted by a spectrometer; illuminating the object with a primary electron beam; receiving secondary electrons of various energy levels the spectrometer, wherein the secondary electrons are formed by an interaction between the primary electron beam and the object; selectively accepting, by the spectrometer via the input grid, a portion of the received secondary electrons with energy levels that are within the spectral range of the energy band; generating an image from secondary electrons accepted by the spectrometer.