US3927321A - Electron microscope beam tube - Google Patents

Electron microscope beam tube Download PDF

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Publication number
US3927321A
US3927321A US463630A US46363074A US3927321A US 3927321 A US3927321 A US 3927321A US 463630 A US463630 A US 463630A US 46363074 A US46363074 A US 46363074A US 3927321 A US3927321 A US 3927321A
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Prior art keywords
tube
weight percent
charged particles
focusing
disposed
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Expired - Lifetime
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US463630A
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English (en)
Inventor
Leonard M Welter
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Nanometrics Inc
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American Optical Corp
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Application filed by American Optical Corp filed Critical American Optical Corp
Priority to US463630A priority Critical patent/US3927321A/en
Priority to CA222,351A priority patent/CA1024268A/fr
Priority to DE19752515320 priority patent/DE2515320A1/de
Priority to JP50048279A priority patent/JPS50147662A/ja
Priority to GB1711875A priority patent/GB1511153A/en
Application granted granted Critical
Publication of US3927321A publication Critical patent/US3927321A/en
Assigned to WARNER LAMBERT COMPANY, A CORP. OF DEL. reassignment WARNER LAMBERT COMPANY, A CORP. OF DEL. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: AMERICAN OPTICAL CORPORATION,
Assigned to WARNER LAMBERT TECHNOLOGIES, INC., A CORP. OF TX. reassignment WARNER LAMBERT TECHNOLOGIES, INC., A CORP. OF TX. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: WARNER LAMBERT COMPANY
Assigned to NANOMETRICS, INC. reassignment NANOMETRICS, INC. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: WARNER LAMBERT TECHNOLOGIES, INC.,
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
    • H01J37/09—Diaphragms; Shields associated with electron or ion-optical arrangements; Compensation of disturbing fields
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/12—Silica-free oxide glass compositions
    • C03C3/16—Silica-free oxide glass compositions containing phosphorus
    • C03C3/21—Silica-free oxide glass compositions containing phosphorus containing titanium, zirconium, vanadium, tungsten or molybdenum
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C4/00—Compositions for glass with special properties
    • C03C4/14—Compositions for glass with special properties for electro-conductive glass
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
    • H01J37/06—Electron sources; Electron guns
    • H01J37/073—Electron guns using field emission, photo emission, or secondary emission electron sources

Definitions

  • ABSTRACT In a charged particle microprobe system having, for example, a housing defining a vacuum chamber, a source of charged particles such as a field emission tip disposed in the chamber for generating charged particles, means for establishing focusing and accelerating fields for forming a beam of said charged particles and including means for either deflecting said beam according to a predetermined program whereby the beam may scan a specimen to be examined or including additional means for focusing the beam, inclusion of an apertured conductive glass cylinder spaced about the charged particle beam path as a nonchargeable, field-free means for maintaining a vacuum 315/31 R H01J 37/26 SCAN CONTROL chamber around said beam in the region of said de- S Em .wwe F l l l l l l l l mm 1 miwl T m 2 f U ms W
  • the electron optical system described in the aforementioned references includes disclosures of systems including a field emission tip for generating charged particles; electrode means for establishing an electrostatic focusing and accelerating field for forming the charged particles into a beam (often referred to as a first and a second anode); a field electrode for establishing an electrostatic field for extracting the charged particles from the, field emission tip (often referred to as an extraction electrode or an intermediate electrode, since it is principally disposed intermediate the tip and the first anode); and voltage supply means connected to the tip and the focusing and accelerating electrode means and the field electrode to supply electrical po- -.tential between the named elements to establish the requisite operating electric fields.
  • One of the common objectives of the aforementioned inventions is the protection of the electron beam formed from influences external to the operating structural elements of the microprobe system.
  • deflection coils are provided for causing the particle beam to scan a specimen to be examined.
  • These deflection coils are usually magnetic devices producing a magnetic flux by the coil at right angles to the mean path of the electron beam. The action of the magnetic flux as it is generated and allowed to collapse causes the electron beam to be deflected back and forth in a predetermined path.
  • the inclusion of second coil means operative at right angles to the flux produced by the first coil allows deflection in both x and y directions and thus with properly correlated signals can cause the beam to scan, in a regular manner, the surface of the specimen to be examined in a manner much similar to the scan of an electron beam of a cathode ray tube.
  • the scanning charged particle microprobe system is a field emission device such as disclosed and described in detail in the references cited above, ultrahigh vacuums are maintained within the vacuum housing wherein the charged particle beam is generated.
  • the specimen chamber which is usually located immediately below the electron gun chamber is usually also maintained in a relatively high vacuum though not necessarily to quite the degree of the field emission producing vacuum electron gun chamber.
  • This shielding tube is thus positioned between the deflection or focusing coil and the electron beam path and prevents the coil from being impinged upon by stray electrons.
  • This structural arrangement also further shields the beam from external electrical influences which may exist around the coil. It has been past practice that these shields be made from materials which are recognized as very good insulators or, in the alternative, very good conductors, depending upon the place installation and the influence to be exerted by the surrounding coil.
  • the present invention provides a tube of uniform, homogeneous structure which provides the desired uniform electrical and physical properties.
  • an improvement in the charged particle microprobes which conventionally include a housing defining a vacuum chamber. a source of charged particles disposed within the vacuum chamber, and various means such as electro-static or electro-magnetic coils for focusing and/or accelerating the charged particles into a beam as well as for deflecting the formed beam in a predetermined pattern such as a raster for examining a portion of a specimen.
  • the present invention is specifically directed to improvements in shielding tubes which conventionally form part of the vacuum housing and about which the various means for focusing, accelerating or deflecting the beam are disposed.
  • Applicants improvement is directed to the inclusion of a cylindrical tube which is generally physically and electrically symmetrical about the longitudinal axis of the tube and wherein the tube is disposed within the microprobe system with its axis aligned with the beam.
  • the tube is further in electrical contact with a voltage source (in the preferred embodiment maintained at ground potential) and the shield is formed of a non-magnetic yet conductive material having a substantially uniform cross-sectional conductivity and a predetermined value of resistance over its axial length.
  • the tube is com- 4 posed of a conductive glass providing a homogeneous element exhibiting the desired properties of a plurality of prior art devices; however, free of the disadvantages of these prior art devices.
  • FIG. 1 is a diagrammatic representation of a microprobe system including the present invention
  • FIG. 2 is a partial cross-sectional view of a field emission microprobe including the present invention
  • FIG. 3 is a graph showing current versus voltage for a number of semi-conductive glasses according to the present invention.
  • FIG. 4 is a graph of current versus time for an illustrative semi-conductive glass according to the present invention.
  • FIG. 5 is a graph of the equilibrium current plotted against equilibrium voltage for a semi-conductive glass according to the present invention.
  • reference numeral 10 indicates a scanning charged particle microprobe such as a field emission scanning electron microscope in which the present invention is illustrated. It is important to note that while the present disclosure speaks illustratively in terms of electron microscopes, it is quite feasible and practical that a preferred embodiment of the invention may be embodied in a variety of charged particle microprobes. To this extent, the source of particles could be of the thermionic or field emission type and productive of either electrons or positively charged ions.
  • a potential source or voltage means 11 which provides the various levels of operating voltages to the electrodes of the scanning electron microscope 10 which is illustrated.
  • a second voltage supply unit, the video detection, receiver and scan control 12 supplies the functions to the related detection and scan control for scanning of the specimen by the electron beam 13 and display of the desired view the specimen undergoing interrogatron.
  • the field emission tip constitutes a principal feature of the instrument.
  • the tip 21 produces a highly coherent intensive beam 13 of electrons capable of being readily focused and imaged as a very small spot upon the surface of a specimen l8.
  • Specimen 18 is shown mounted on a specimen holder 17 which, in conjunction with structure not shown, but well known in the art, positions specimen 18 with respect to the focused beam 13 of charged particles (in the case of the illustrated field emission SEM are electrons).
  • Extractional electrode 22 is disposed in juxtaposition to the field emission tip 21 and when impressed with a voltage from a source (Ve) causes the requisite electrical field to initiate field emission of electrons.
  • Ve voltage from a source
  • Electrode 23 serves as the first anode in the SEM and is often maintained at a potential approximately equal to that of the extraction electrode by a voltage source (V which may be a separate or common source to V
  • a voltage source V which may be a separate or common source to V
  • Voltage source V is connected to second anode 24 and applies the main accelerating voltage thereto.
  • second anode 24 is maintained generally at ground potential and tip 21 is maintained at a highly negative potential (such as KV).
  • Electrode 22 and anode 23 are maintained negative from ground at approximately 13 to 19 kilovolts respectively depending upon the mode of operation of the field emission SEM.
  • anode 23 and anode 24 the main focusing and accelerating field produced by relative different potentials upon these two electrodes.
  • Electrons are extracted from tip 21 in a beam 13 and pass through apertures 22a, 23a and 24a in electrodes 22 and anodes 23 and 24, respectively, to be finally focused upon specimen 18.
  • extraction electrode 22 includes two main members 32 and 35 (See FIG. 2).
  • Upper member 35 is disposed in juxtaposition to field emission tip 21 and includes a wide angle aperture 35a centrally aligned with apertures 23a and 24a.
  • Lower member 32 is dis posed below member 35 and in relatively close position to anode 23.
  • Lower member 32 includes a centrally located aperture 32a also aligned with apertures 23a and 24a as well as aperture 35a.
  • aperture 32a is of a substantially smaller diameter and serves to define the size of beam 13 which is focused on specimen 18. One of the many purposes of this defining aperture is to minimize the opportunity of beam 13 impinging upon SEM elements downstream.
  • bulk resistor 40 is disposed intermediate lower extraction electrode member 32 and first anode 23.
  • Resistor 40 is geometrically symmetrical about an axis coincident with electron beam 13 and has physical properties of material stability under high vacuum and when bombarded with charged corpuscular particles.
  • Resistor 40 includes an axial centrally aligned aperture 40a which is aligned with apertures 22a, 23a, and 24a.
  • Resistor 40 is conveniently disposed in insulator 31 in axial bore 31a also generally centrally located therein.
  • Located generally downstream of anodes 23 and 24' is the section of scanning electron microscope which includes the deflection coils 42 which raster the electron beam 13 in the manner previously described. Deflection coils 42 generally surround a beam tube 44 and illustrate one embodiment of the invention herein described.
  • beam tube 44 is located physically in the deflection section 46 of the scanning electron microscope and forms the isolating member between the high vacuum portion of the electron microscope and the exterior accessory equipment (such as the deflection coils 42).
  • Beam tube 44 is generally cylindrical in shape and composed of a conductive glass material which is disclosed in patent application Ser. No. 463,628 being filed in the name of E. W. Deeg et a] concurrently herewith.
  • Beam tube 44 includes an axial centrally alignedaperture 44a aligned 6 with apertures 22a, 23a, 24a, and 40a.
  • Beam tube 44 is disposed within the deflection section 46 in conjunction with means 48 such as O-rings for forming a seal between the aperture portion 44a of beam tube 44 and the area generally external thereto such as that including deflection coils 42.
  • the resistance of the conductive glass of which the beam tube 44 is made is proportional to the length of the current path which, in the present embodiment, is generally parallel to beam 13 being the path between upper retaining member 460 of the deflection section and the lower retaining member 46b of the deflection section, and inversely proportional to the cross-sectional area of the current path.
  • the preferred value of resistance is in the range of approximately 10 to 10 ohms. This value has been found effective to allow the bleed off" of any charge which might otherwise build upon the beam tube 44, either from the effects of bombardment of the tube by electron beam 13 or by the induced voltage from deflection coils 42.
  • the beam tube be grounded at one or more points throughout its length to insure an adequate path for the bleed off of any charge which might otherwise tend to build on beam tube 44. Accordingly, it may be convenient to provide such a grounding contact through Orings 48, since these, in order to provide an adequate seal for the open high vacuums within the aperture 44a are in intimate contact with the conductive material of beam tube 44.
  • beam tube 44 is a bored cylinder having a radius 0.7 cm, a length 2 cm and an internal bore of radius 0.5 cm.
  • the particular glass composition chosen was EWD 553 as disclosed in the aforementioned application being filed concurrently herewith. This particular sample was chosen over the others disclosed because of its characteristics (conductivity, etc.) with respect to the physical preferences of the intended use. It should be pointed out that other conductive glasses such as disclosed in the abovementioned patent application may exhibit more favorable properties for a different embodiment (either in scanning electron microscope or an ion probe) which cause different relative physical or electrical properties related to such as size, or voltage and resistance values.
  • an additional embodiment of the invention is illustrated including the combination of a conductive glass beam tube 50, hereinafter described, which is disposed in a magnetic lens section 52 of a scanning electron microscope.
  • Beam tube 50 is also a cylindrically shaped structure, similar to tube 42, having an outer radius of about 0.7 cm, an inner bore of about 0.5 cm and a length of about 5 cm.
  • Tube 50 is disposed in upper plate 52a and lower plate 521) in deflection section 52 in vacuum-sealed relationship, such as with O-rings" 48.
  • Magnetic focusing coils 54 are disposed around the outer circumference of tube 50, being electrically connected to a focusing control (not shown).
  • Tube 50 is electrically connected to grounding means, as through O-rings 48 and plates 52a and 52b to the main frame of the electron probe to enable any electrical charge which might otherwise build locally on tube 50 to be bled off.
  • Tube 50 preferably of a conducting glass such as EWD 553 selected from the group of glasses disclosed by E. W. Deeg et al in Pat. application Ser. No.
  • the present combination of a conductive glass beam tube disposed either in the deflection section or magnetic lens section exhibits a variety of advantages.
  • the beam tubes 44 and 50 are formed of a homo- 8 sisting essentially of about 25 to 35 wt.% of V about 35 to 45 wt.% of M00 about to 20 wt.% of P 0 up to about wt.% of BaO, up to about 5 wt.% of A1 0 up to about 10 wt.% Fe O up to about 2 wt.% of CaO and up to about 4 wt.% of C0 0
  • the total of the V 0 plus M00 plus P 0 is equal to about 70 to 90 wt.% of the total glass composition.
  • the glass compositions will have:
  • B About 2 to 10 wt.% of at least one oxide selected from the group consisting of Fe O and C0 0,;
  • any placed in a vacuum oven and stabilized to equilibrium externally caused influence, such as by coils 42, will be 45 at the desired temperature.
  • the conductivity of the uniformly received when imposed upon the tubes 44 sample at that temperature may then be measured. and 50. Since the tubes 44 and are likewise uni- Measurements of conductivity have been made at a formly conductive, this external influence may be imnumber of temperatures over the range of 24C to mediately and uniformly removed. Therefore, the elec- 104C. trical symmetry of the environment of electron beam 50 Measurements of the electrical conductivity of the 13 is continually maintained.
  • Non-symmetrical elements in the 001- have been made on annular samples having an inner umn can induce electrical interference with the flow of diameter of about 0.6 cm, an outer diameter of 2.3 cm electron beam 13 by deviation of some or many of the and a length of 1.1 cm.
  • the electrical conductivity charged particles causing such as astigmatism, aberrameasurements were made at the low electrical field tion, etc. All of the reasons for such disturbance are not strengths.
  • the methods of testing are disclosed in the known. However, localized charged ionization field aforementioned application being filed concurrently effects are frequencly cited as causes. with this application.
  • Glass compositions which are considered to be most favorable in the present invention include those conshown in the graph of FIG. 3.
  • the resistances which are calculated for each of the data points shown in FIG. 3 are given in the Table 2 below.
  • the values of the resistances are given in megohms.
  • EWD553A 0.085 20.8 20.0 20.0 20.0 19.2 19.2
  • EWD-553B 0.2 50.0 52.6 52.0 51.3 50.0 49.3
  • EWD-560A 0.2 48.0 45.0 44.0 41.0 40.0
  • EWD562A 0.1 38.4 37.0 41.7 37.8 36.3 36.0
  • the resistance property of the samples measured may be non-ohmic in nature.
  • a relatively strong non-linearity in the resistance is observed with increasing voltage up to a threshold voltage.
  • the current is observed to increase by an amount greater than that which is predicted by Ohms Law. Beyond a specific voltage, the current is observed to rise rapidly to an initial value and, thereafter, is observed to creep slowly up to a final equilibrium value.
  • the voltage current plot of sample EWD-553A, ob tained at high electrical field strengths, is shown in FIG. 5.
  • the data points correspond to the final equilibrium values observed. A strong nonlinearity begins to occur at field strengths which the glass can hold off or sustain is about 13,000V/cm.
  • the data points labelled x and x, in FIG. 5 correspond to the initial and final values, respectively, of the current and electric field strength for the data shown in FIG. 4.
  • the resistivities of the samples are calculated from the slopes of the straight lines in the current versus voltage plot shown in FIG. 3, in ambient air, at room temperature, and are listed below in Table 3.
  • the resistivity of glass sample EWD-553A, as measured at a pressure of 3.5 X 10 Torr was found to be 2.2 X 10 ohm.cm at 5V DC. This value compares with the value 2.5 X 10 ohm.cm measured for the same sample in ambient air. The small difference observed may be due to measurement errors or differences in temperature of the sample at the time of measurement.
  • P P h' -IA'T Where P is a resistivity, P is a constant, E* is a socalled activation energy for conduction, k is the Boltzmann factor.
  • the activation energy for conduction, 13* is found to be about 0.5eV.
  • the conduction mechanism may be considered to be ionic if 0.7 eV E* 2.4 eV and electronic if E* 0.7 eV. It seems apparent that the primary conduction mechanism in the semiconducting glasses is electronic.
  • a charged particle microprobe system including a housing defining a vacuum chamber;
  • apertured means disposed in said housing for establishin g focusing and accelerating fields for forming a beam of said charged particles
  • a tube being generally physically and electrically symmetrical about an axis, said tube being disposed in said microprobe with its axis substantially aligned with said beam and in electrical contact with a voltage source, said tube being formed of a non-magnetic material having a substantially uniform cross-sectional conductivity and a predetermined value of resistance of 10 to 10 ohms/cm over its axial length whereby said tube is electrically conductive yet free of high eddy currents.
  • said conductive glass material has a composition consisting essentially of about to weight percent of the essential ingredients V 0 M00 and P 0 the V 0 being present in an amount ranging from 27.8 to 50 weight percent of the essential ingredients;
  • the M00 being present in an amount ranging from 38.9 to 64.3 weight percent of the essential ingredients
  • the P 0 being present in an amount ranging from 1 1.3 to 28.6 weight percent of the essential ingredients

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)
US463630A 1974-04-24 1974-04-24 Electron microscope beam tube Expired - Lifetime US3927321A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US463630A US3927321A (en) 1974-04-24 1974-04-24 Electron microscope beam tube
CA222,351A CA1024268A (fr) 1974-04-24 1975-03-18 Tube a vide pour fisceau de microscope electronique
DE19752515320 DE2515320A1 (de) 1974-04-24 1975-04-08 Strahlroehre fuer elektronenmikroskop
JP50048279A JPS50147662A (fr) 1974-04-24 1975-04-22
GB1711875A GB1511153A (en) 1974-04-24 1975-04-24 Charged particle microprobe systems

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US463630A US3927321A (en) 1974-04-24 1974-04-24 Electron microscope beam tube

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4041316A (en) * 1974-09-20 1977-08-09 Hitachi, Ltd. Field emission electron gun with an evaporation source
US4071765A (en) * 1974-12-17 1978-01-31 U.S. Philips Corporation Electron microscope
US4427886A (en) 1982-08-02 1984-01-24 Wisconsin Alumni Research Foundation Low voltage field emission electron gun
US4926055A (en) * 1988-01-25 1990-05-15 Jeol Ltd. Field emission electron gun
EP0390118A3 (fr) * 1989-03-30 1991-07-17 Hitachi, Ltd. Microscope électronique à balayage à émission de champ et procédé de contrôle de l'angle d'ouverture du faisceau
US5376792A (en) * 1993-04-26 1994-12-27 Rj Lee Group, Inc. Scanning electron microscope
US5763889A (en) * 1996-03-22 1998-06-09 Jeol Ltd. Electron beam-generating apparatus
US20060219946A1 (en) * 2003-01-08 2006-10-05 Tsuyoshi Inanobe Electron beam apparatus and method for production of its specimen chamber
US20110186745A1 (en) * 2008-08-08 2011-08-04 Hiroyasu Kqaga Charged particle gun and focused ion beam apparatus using the gun

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2234281A (en) * 1938-02-10 1941-03-11 Fides Gmbh Shielded electron microscope
US3206635A (en) * 1961-04-27 1965-09-14 Gen Electric Electron stream focusing
US3223837A (en) * 1961-07-10 1965-12-14 First Pennsylvania Banking And Beam probe system and apparatus
US3760383A (en) * 1971-07-01 1973-09-18 Gen Electric Erration storage system with collimated electron beam for minimal spherical ab

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2234281A (en) * 1938-02-10 1941-03-11 Fides Gmbh Shielded electron microscope
US3206635A (en) * 1961-04-27 1965-09-14 Gen Electric Electron stream focusing
US3223837A (en) * 1961-07-10 1965-12-14 First Pennsylvania Banking And Beam probe system and apparatus
US3760383A (en) * 1971-07-01 1973-09-18 Gen Electric Erration storage system with collimated electron beam for minimal spherical ab

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4041316A (en) * 1974-09-20 1977-08-09 Hitachi, Ltd. Field emission electron gun with an evaporation source
US4071765A (en) * 1974-12-17 1978-01-31 U.S. Philips Corporation Electron microscope
US4427886A (en) 1982-08-02 1984-01-24 Wisconsin Alumni Research Foundation Low voltage field emission electron gun
WO1984000610A1 (fr) * 1982-08-02 1984-02-16 Wisconsin Alumni Res Found Canon electronique a emission de champ a basse tension
US4926055A (en) * 1988-01-25 1990-05-15 Jeol Ltd. Field emission electron gun
EP0390118A3 (fr) * 1989-03-30 1991-07-17 Hitachi, Ltd. Microscope électronique à balayage à émission de champ et procédé de contrôle de l'angle d'ouverture du faisceau
US5142148A (en) * 1989-03-30 1992-08-25 Hitachi, Ltd. Field emission scanning electron microscope and method of controlling beam aperture angle
US5376792A (en) * 1993-04-26 1994-12-27 Rj Lee Group, Inc. Scanning electron microscope
US5763889A (en) * 1996-03-22 1998-06-09 Jeol Ltd. Electron beam-generating apparatus
US20060219946A1 (en) * 2003-01-08 2006-10-05 Tsuyoshi Inanobe Electron beam apparatus and method for production of its specimen chamber
US20080048118A1 (en) * 2003-01-08 2008-02-28 Tsuyoshi Inanobe Electron Beam Apparatus and Method for Production of Its Specimen Chamber
US7435958B2 (en) * 2003-01-08 2008-10-14 Hitachi High-Technologies Corporation Electron beam apparatus and method for production of its specimen chamber
US7566892B2 (en) 2003-01-08 2009-07-28 Hitachi High-Technologies Corporation Electron beam apparatus and method for production of its specimen chamber
US20110186745A1 (en) * 2008-08-08 2011-08-04 Hiroyasu Kqaga Charged particle gun and focused ion beam apparatus using the gun
US8399863B2 (en) * 2008-08-08 2013-03-19 Hitachi High-Technologies Corporation Charged particle beam apparatus using an electrostatic lens gun

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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:WARNER LAMBERT COMPANY;REEL/FRAME:004034/0707

Effective date: 19820514

Owner name: WARNER LAMBERT COMPANY, 201 TABOR ROAD, MORRIS PLA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:AMERICAN OPTICAL CORPORATION,;REEL/FRAME:004034/0681

Effective date: 19820513

AS Assignment

Owner name: NANOMETRICS, INC., SUNNYVALE, CA A CORP. OF CA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:WARNER LAMBERT TECHNOLOGIES, INC.,;REEL/FRAME:004113/0670

Effective date: 19821109