Patent ID: 6686590
Filing Date: 2004-02-03
Classification: G01N,H01J

Abstract:
A low-vacuum scanning electron microscope comprising:an electron gun for producing and accelerating an electron beam; condenser lenses for focusing said electron beam onto a specimen placed within a specimen chamber in a low vacuum, said specimen being at a potential, said specimen being at a distance from said condenser lenses; scanning means for scanning said electron beam over said specimen in two directions; voltage generation means for setting the potential of said specimen such that said specimen is at a negative potential with respect to said specimen chamber; detection means for detecting an electric current flowing through said specimen and/or an electric current flowing through a specimen holder holding said specimen thereon; and means for obtaining a scanned image of the specimen based on an output signal from said current detection means, wherein said voltage generation means sets the potential of said specimen to promote an avalanche effect based on information about pressure inside said specimen chamber and on information about the distance between said specimen and said condenser lenses.