Abstract:
A charged particle filter with an integrated energy filter, in which the charged particle emitter, the focusing electrodes, and the deflection electrodes are arranged round a straight axis. Where most energy filters used have a highly curved optical axis, and thus use parts with forms that are difficult to manufacture, the source according the invention uses electrodes surrounding a straight optical axis. A beam of charged particles can be deflected quite far from the axis showing respectable energy dispersion at an energy selecting slit without introducing coma or astigmatism that cannot be corrected, provided that some of the are formed as 120°/60°/120°/60°. Such electrodes can be attached to each other by gluing or brazing of ceramic, and then series of a highly concentric bores can be formed by, e.g., spark erosion.
Abstract:
A charged particle apparatus is equipped with a third stigmator positioned between the objective lens and a detector system, as a result of which a third degree of freedom is created for reducing the linear distortion.Further, a method of using said three stigmators, comprises exciting the first stigmator to reduce astigmatism when imaging the sample, exciting the second stigmator to reduce astigmatism when imaging the diffraction plane, and exciting the third stigmator to reduce the linear distortion.
Abstract:
Commercially available High Resolution Transmission Electron Microscopes (HR-TEM) and Scanning Transmission Electron Microscopes (HR-STEM) are nowadays equipped with correctors for correcting the axial spherical aberration Cs of the so-named objective lens. Inevitably other aberrations become the limiting aberration. For the hexapole type correctors, also known as Rose correctors, or variants thereof, six-fold axial astigmatism, also known as A5, and sixth-order three lobe aberration, also known as D6, introduced by the corrector, are known to become the limiting aberration. The invention shows that by adding a weak hexapole (126) in the cross-over between the hexapoles, a Rose like corrector or a Crewe like corrector free of A5 or D6 can be made, or, by adding both the weak hexapole and a dodecapole, a corrector that is free of both A5 and D6.
Abstract:
A particle source in which energy selection occurs by sending a beam of electrically charged particles eccentrically through a lens so that energy dispersion will occur in an image formed by the lens. By projecting this image onto a slit in an energy selecting diaphragm, it is possible to allow only particles in a limited portion of the energy spectrum to pass. Consequently, the passed beam will have a reduced energy spread. The energy dispersed spot is imaged on the slit by a deflector. When positioning the energy dispersed spot on the slit, central beam is deflected from the axis to such an extent that it is stopped by the energy selecting diaphragm. Hereby reflections and contamination resulting from this beam in the region after the diaphragm are avoided. Also electron-electron interaction resulting from the electrons from the central beam interacting with the energy filtered beam in the area of deflector is avoided.
Abstract:
The invention describes a particle source in which energy selection occurs. The energy selection occurs by sending a beam of electrically charged particles 13 eccentrically through a lens 6. As a result of this, energy dispersion will occur in an image 15 formed by the lens 6. By projecting this image 15 onto a diaphragm 7, it is possible to only allow particles in a limited portion of the energy spectrum to pass. Consequently, the passed beam 16 will have a reduced energy spread. By adding a deflection unit 10, this particle beam 16 can be deflected toward the optical axis 2. One can also elect to deflect a beam 12 going through the middle of the lens 6—and having, for example, greater current—toward the optical axis.
Abstract:
Particle-optical rotationally symmetrical lenses inevitably have chromatic aberration. This lens fault determines the limit of the resolution of known particle-optical apparatus at a comparatively low acceleration voltage (0.5 kV to 5 kV) of the particle beam. This lens fault cannot be eliminated by compensation by means of rotationally symmetrical fields. In order to enhance the resolution of the particle-optical apparatus nevertheless, it has already been proposed to mitigate said lens fault by means of a Wien type corrector. Such a known configuration is provided with a number of electrical and magnetic multipoles. In order to achieve easier adjustment of the various multipole fields, the pole faces (30-i) governing the multipole fields according to the invention have a specific length L=(2.pi..sup.2 n.sup.2)/(K.sub.obj.sup.2 C.sub.c,obj), in which K.sub.obj is the strength of the focusing lens to be corrected and C.sub.c,obj is the coefficient of chromatic aberration of this lens.
Abstract:
A charged particle filter with an integrated energy filter, in which the charged particle emitter, the focusing electrodes, and the deflection electrodes are arranged round a straight axis. Where most energy filters used have a highly curved optical axis, and thus use parts with forms that are difficult to manufacture, the source according the invention uses electrodes surrounding a straight optical axis. A beam of charged particles can be deflected quite far from the axis showing respectable energy dispersion at an energy selecting slit without introducing coma or astigmatism that cannot be corrected, provided that some of the are formed as 120°/60°/120°/60°. Such electrodes can be attached to each other by gluing or brazing of ceramic, and then series of a highly concentric bores can be formed by, e.g., spark erosion.
Abstract:
A particle source in which energy selection occurs by sending a beam of electrically charged particles eccentrically through a lens so that energy dispersion will occur in an image formed by the lens. By projecting this image onto a slit in an energy selecting diaphragm, it is possible to allow only particles in a limited portion of the energy spectrum to pass. Consequently, the passed beam will have a reduced energy spread. The energy dispersed spot is imaged on the slit by a deflector. When positioning the energy dispersed spot on the slit, central beam is deflected from the axis to such an extent that it is stopped by the energy selecting diaphragm. Hereby reflections and contamination resulting from this beam in the region after the diaphragm are avoided. Also electron-electron interaction resulting from the electrons from the central beam interacting with the energy filtered beam in the area of deflector is avoided.
Abstract:
Electron-beam-induced chemical reactions with precursor gases are controlled by adsorbate depletion control. Adsorbate depletion can be controlled by controlling the beam current, preferably by rapidly blanking the beam, and by cooling the substrate. The beam preferably has a low energy to reduce the interaction volume. By controlling the depletion and the interaction volume, a user has the ability to produce precise shapes.
Abstract:
The focusing device 8 for the primary beam in a scanning electron microscope (SEM) consists in known manner of a combination of a magnetic gap lens 34 and a monopole lens 38. The secondary electrons released from the specimen are detected in accordance with the invention by a detector whose deflection unit 52, or the actual detector 64, 66, is arranged in a field-free space between the gap lens and the monopole lens. This space is rendered field-free by a screening plate 44 arranged underneath the gap lens. In order to achieve a high detector efficiency and a large field of vision, the pole tip of the focusing device 8 is provided with an attraction electrode 42 whose potential is higher than that of the specimen.