Abstract: The invention relates to a blocking member to be placed in the diffraction plane of a TEM. It resembles the knife edge used for single sideband imaging, but blocks only electrons deflected over a small angle. As a result the Contrast Transfer Function of the TEM according to this invention will equal that of a single sideband microscope at low frequencies and that of a normal microscope for high frequencies. Preferable the highest frequency blocked by the blocking member is such that a microscope without the blocking member would show a CTF of 0.5.

Abstract: The invention relates to a hybrid phase plate for use in a TEM. The phase plate according to the invention resembles a Boersch phase plate in which a Zernike phase plate is mounted. As a result the phase plate according to the invention resembles a Boersch phase plate for electrons scattered to such an extent that they pass outside the central structure (15) and resembles a Zernike phase plate for scattered electrons passing through the bore of the central structure. Comparing the phase plate of the invention with a Zernike phase plate is has the advantage that for electrons that are scattered over a large angle, no electrons are absorbed or scattered by a foil, resulting in a better high resolution performance of the TEM. Comparing the phase plate of the invention with a Boersch phase plate the demands for miniaturization of the central structure are less severe.

Abstract: The invention provides multiple detectors that detect electrons that have passed through a sample. The detectors preferably detect electrons after the electrons have been passed through a prism that separates electrons according to their energies. Electrons in different energy ranges are then detected by different detectors, with preferably at least one of the detectors measuring the energy lost by the electrons as they pass through the sample. One embodiment of the invention provides EELS on core-loss electrons while simultaneously providing a bright-field STEM signal from low-loss electrons.

Abstract: The invention relates to a TEM with a corrector (330) to improve the image quality and a phase plate (340) to improve contrast. The improved TEM comprises a correction system completely placed between the objective lens and the phase plate, and uses the lenses of the corrector to form a magnified image of the diffraction plane on the phase plate.

Abstract: The invention relates to a method for correcting distortions introduced by the projection system (106) of a TEM. As known to the person skilled in the art distortions may limit the resolution of a TEM, especially when making a 3D reconstruction of a feature using tomography. Also when using strain analysis in a TEM the distortions may limit the detection of strain. To this end the invention discloses a detector equipped with multipoles (152), the multipoles warping the image of the TEM in such a way that distortions introduced by the projection system are counteracted. The detector may further include a CCD or a fluorescent screen (151) for detecting the electrons.

Abstract: The invention relates to a hybrid phase plate for use in a TEM. The phase plate according to the invention resembles a Boersch phase plate in which a Zernike phase plate is mounted. As a result the phase plate according to the invention resembles a Boersch phase plate for electrons scattered to such an extent that they pass outside the central structure (15) and resembles a Zernike phase plate for scattered electrons passing through the bore of the central structure. Comparing the phase plate of the invention with a Zernike phase plate is has the advantage that for electrons that are scattered over a large angle, no electrons are absorbed or scattered by a foil, resulting in a better high resolution performance of the TEM. Comparing the phase plate of the invention with a Boersch phase plate the demands for miniaturization of the central structure are less severe.

Abstract: The invention relates to a TEM with a corrector (330) to improve the image quality and a phase plate (340) to improve contrast. The improved TEM comprises a correction system completely placed between the objective lens and the phase plate, and uses the lenses of the corrector to form a magnified image of the diffraction plane on the phase plate.

Abstract: An electron source for, for example, an electron microscope cannot exhibit a high brightness and a large beam current at the same time, because the virtual emitter dimension is enlarged by Coulomb repulsion in the electron beam in the case of a large beam current, thus reducing the brightness. In a conventional electron source switching-over could take place from a high brightness to a large beam current by varying the dimension of a beam-limiting diaphragm; however, this is objectionable because the location of such a diaphragm is not readily accessible. In accordance with the invention said switching-over can take place by arranging two lenses 26, 28 in the source, which lenses parallelize In the described circumstances the beam either directly behind the emitter 4 (large current) or directly in front of the diaphragm aperture 32 (high brightness).

Abstract: Multi-beam lithography apparatus is used for writing patterns on a substrate 14 such as a wafer for ICs. The patterns may have details of various dimensions. In order to enhance the production rate, it is attractive to write fine details with a small spot 16 and large details with a large spot. It is known to vary the spot size by varying the emissive surface of the electron source. In accordance with the invention the spot size is varied by varying the size 22 of the beam limiting aperture 20, thus enabling optimization of the beam current in dependence on the spot size. A preferred embodiment is provided with an additional (condenser) lens 24 such that the object distance remains constant when the magnification of the lens system 18, 24 is varied.

Abstract: Multi-beam lithography apparatus is used for writing patterns on a substrate 14 such as a wafer for ICs. The patterns may have details of various dimensions. In order to enhance the production rate, it is attractive to write fine details with a small spot 16 and large details with a large spot. It is known to vary the spot size by varying the emissive surface of the electron source. In accordance with the invention the spot size is varied by varying the size 22 of the beam limiting aperture 20, thus enabling optimization of the beam current in dependence on the spot size. A preferred embodiment is provided with an additional (condenser) lens 24 such that the object distance remains constant when the magnification of the lens system 18, 24 is varied.

Abstract: An electron microscope comprises an energy-selective filter (10) which is arranged ahead of the high-voltage field in the electron gun (2). Because the filter carries high-voltage potential and is arranged within the gun space (14) which is filled with SF.sub.6 gas, problems arise regarding electrical and mechanical passages to the filter. Notably the centering of the filter is problematic. In order to enable suitable aperture adjustment of the filter nevertheless (for current limitation and for avoiding optical aberrations introduced into the beam by the filter), there is provided an entrance diaphragm (30) which is rigidly connected to the filter parts, notably to a pole face or to a field-defining closing piece (48a) of the filter.