Scanning Confocal Electron Microscopy

Abstract

A scanning confocal microscope and methods are provided for configuring scanning confocal microscopes for imaging specimens, such as, high resolution imaging of thick non-optically transparent specimens including imaging of buried or subsurface features of thick non-optically transparent structures. The scanning confocal microscope, such as a scanning confocal electron microscope (SCEM), is configured to image structures buried in thick specimens, such as specimens greater than eight microns thick, utilizing confocal imaging principles. A scanning confocal microscope includes an illumination source, a specimen, and a detector. The illumination source provides a focused radiation beam that is applied to the specimen. The detector detects an interaction signal from the specimen. The scanning confocal microscope is configured to operate in the confocal imaging mode, where the imaging source, specimen and detector are arranged to be located at conjugate image points. The focused radiation beam provided by the illumination source includes an electron beam, a proton beam, an ion beam, or an x-ray beam. The focused radiation beam provided by the illumination source is capable of penetrating thick non-optically transparent specimens, unlike visible light or optical probes that cannot penetrate significant depths in optically dense specimens. The incident probe is sequentially scanned across a region of interest of the specimen and the net integrated confocal intensity at each point is detected and used to provide an image display. A scanning confocal electron microscope (SCEM) is provided that permits resolutions better than 100 nanometers for materials as thick as 8-10 microns. The image resolution provided is equal to or better than typical high flux x-ray sources, while operating at speeds up to one hundred times faster and the scanning confocal microscope can be located in a conventional laboratory space.