Abstract:
An electron gun comprising an electron emission cathode (1), a control electrode (6) and an extractor (7) wherein the electron emission cathode is mode of rare earth hexaboride and a tip of the electron emission cathode is located between the control electrode and the extractor.
Abstract:
An electron gun cathode (104) is column shaped, and emits electrons by being heated. A holder (103), which covers the bottom and sides of the electron gun cathode, has electrical conductivity and holds the electron gun cathode, and is composed of a material that does not easily react with the electron gun cathode when in a heated state, is provided. The tip of the electron gun cathode (104) protrudes from the holder (103) so as to be exposed, and electrons are emitted from the tip toward the front by applying an electric field to the tip.
Abstract:
A variable shaping type electron beam exposing apparatus is provided which comprises an electron gun (10) which irradiates an electron beam from the front end of a cathode chip (12, 52); shaping plates (28, 34) having openings of variable shapes for shaping the electron beam irradiated from the electron gun (10) into the shapes of these openings; and an objective lens (50) for focusing the electron beam passed through the shaping plates (28, 34) into a predetermined shape on a sample. In this apparatus, the cathode chip (12, 52) is made of single-crystal lanthanum hexaboride whose axial orientation is 310, the front end of it is formed into a circular conical shape, and half the vertical angle of the front end is set to be between 60° and 85°. The maximum area of the image on the sample is between 2 to 50 µm 2 . The cathode (12, 52) of the electron gun (10) is of a material whose ratio of work function to temperature for reaching a vapor pressure of 1 x 10- 5 Torr is below 1.5 x 10 -3 eV/deg.
Abstract:
A thermionic cathode of an embodiment includes a carbon coating applied to an outer surface of the side, the carbon coating comprising a contiguous extended portion surrounding the upper section and spaced apart from said upper section by a gap having 1 μm or more and 10 μm or less in width and having a difference of 1 μm or less in the width between a maximum value and a minimum value in a periphery of the electron emitting surface.
Abstract:
An electron source is made from mixed-metal carbide materials of high refractory nature. Producing field-enhanced thermionic emission, i.e., thermal-field or extended Schottky emission, from these materials entails the use of a certain low work function crystallographic direction, such as, for example, (100), (210), and (310). These materials do not naturally facet because of their refractory nature. The disclosed electron source made from transition metal carbide material is especially useful when installed in a scanning electron microscope (SEM) performing advanced imaging applications that require a high brightness, high beam current source.
Abstract:
An electron gun cathode (104) is column shaped, and emits electrons by being heated. A holder (103), which covers the bottom and sides of the electron gun cathode, has electrical conductivity and holds the electron gun cathode, and is composed of a material that does not easily react with the electron gun cathode when in a heated state, is provided. The tip of the electron gun cathode (104) protrudes from the holder (103) so as to be exposed, and electrons are emitted from the tip toward the front by applying an electric field to the tip.
Abstract:
Electron emission materials consisting of carbides, borides, and oxides, and related mixtures and compounds, of Group IVB metals Hf, Zr, and Ti, Group IIA metals Be, Mg, Ca, Sr, and Ba, and Group IIIB metals Sc, Y, and lanthanides La through Lu are used in electrodes. The electron emission materials include ternary Group IVB-IIIB, IVB-IIA, and IIIB-IIA oxides and quaternary Group IVB-IIIB-IIA oxides. These electron emission materials are typically contained in a refractory metal matrix formed of tungsten, molybdenum, tantalum, rhenium, and their alloys, but may also be used by themselves. These materials and electrodes have high melting points, low vapor pressures, low work functions, high electrical and thermal conductivity, and high thermionic electron emission and field emission properties.