Method and arrangement for detecting the secondary particles released on a sample by a corpuscular beam

摘要

In conventional detector systems, both secondary electrons (SE) and backscattered electrons (RP) contribute to the measurement signal. The recorded secondary electron image of the sample is therefore always superimposed by a weak backscattered electron image. In order to suppress the signal components of backscattered electrons (RP), it is proposed to modulate the strength of the exhaust field by means of a fixed frequency f. The output signal of the detector system then contains a signal component of frequency f whose amplitude corresponds to the intensity of the secondary electron current at the point of the sample surface which is respectively being scanned by the corpuscular beam (PE). This signal component can be filtered out and used to control the intensity of the writing beam of a display device (visual display unit) (CRT). <IMAGE>