US3862419A - Electron-beam illuminating system for an electrical apparatus such as an electron microscope or the like - Google Patents

Electron-beam illuminating system for an electrical apparatus such as an electron microscope or the like Download PDF

Info

Publication number
US3862419A
US3862419A US373415A US37341573A US3862419A US 3862419 A US3862419 A US 3862419A US 373415 A US373415 A US 373415A US 37341573 A US37341573 A US 37341573A US 3862419 A US3862419 A US 3862419A
Authority
US
United States
Prior art keywords
anode
cathode
voltage
acceleration
electron
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US373415A
Other languages
English (en)
Inventor
Lee Veneklasen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens AG filed Critical Siemens AG
Application granted granted Critical
Publication of US3862419A publication Critical patent/US3862419A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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

  • An electron-beam illuminating system for an electrical apparatus such as an electron microscope or the like includes a cathode for supplying the electrons making up the electron-beam.
  • a first anode is disposed beyond the cathode and defines therewith a beam axis extending in beam direction.
  • a positive bias voltage on the first anode determines the emission of the cathode.
  • An acceleration anode is disposed beyond the first anode and defines an acceleration path for the electrons emitted by the cathode.
  • An acceleration voltage is applied across the cathode and the acceleration anode.
  • a further electrode is located between the first anode and the accelerating electrode and defines conjointly with the first anode a space therebetween along the beam axis.
  • a voltage is applied to the further electrode which is linearly proportional to the acceleration voltage.
  • An auxiliary lens generates a first image of the source in this space.
  • An electric circuit supplies a voltage to the further electrode which is linearly proportional to the acceleration voltage.
  • the illuminating system is equipped with a cathode which constitutes the source of the electrons and which has an emission determined by the positive bias of a first anode, particularly a field emission cathode;
  • the illuminating system is further provided with an accelerating anode, and an auxiliary lens which is situated in front of the accelerating anode and generates at the input of the acceleration path a first image of the source at a fixed point of the axis; and with a further lens which images the first image of the source once more.
  • Electron-beam illuminating systems with a field emission cathode normally have the property that the focusing of the emerging electron beam is affected by the' ratio of the first anode voltage to the accelerating voltage.
  • this shortcoming is corrected in first approximation by the fact that the first image of the source, projected by the auxiliary lens, is situated in or near the principal plane of the lens formed by the accelerating system, so that in the ideal case the lens effect of the accelerating system is eliminated.
  • a magnetic lens which images the first image of the source once more, a magnetic lens, whose excitation must be corrected in the event of a change of the accelerating voltage, is provided in the known arrangement.
  • a further electrode is'disposed whose potential, relative to the potential of the accelerating anode, is linearly proportional to the accelerating voltage.
  • the first image of the source is situated in the gap between the first anode and the further electrode and the further lens is formed by the further electrode together with the accelerating anode.
  • the system of the invention affords the advantage that the accelerating system itself takes over the second imaging of the source thereby rendering unnecessary the magnetic lens of the known arrangement. Because the potential of the further electrode is linearly proportional to the accelerating voltage, the further advantage is realized that the lens power of the further lens changes in the same sense as the accelerating voltage if the latter changes, so that the second image remains essentially unaffected.
  • An electron-beam illuminating system of the invention is suitable for an electrical apparatus such as an electron microscope or the like.
  • the system includes a cathode constituting a source for supplying the electrons making up the electron beam.
  • a first anode is disposed beyond the cathode and defines therewith a beam axis extending in beam direction.
  • a first anode ode Beyond the first anode along the beam axis thereis disposed an acceleration anode which defines an acceleration path for the electrons emitted by the cathode.
  • Acceleration voltage supply means establishes an acceleration voltage across the cathode and the accelerating anode.
  • a further electrode is disposed between the first anode and the accelerating electrode, the further electrode and the first anode conjointly defining a space therebetween along the beam axis.
  • An auxiliary lens is disposed along the beam axis ahead of the acceleration anode for'generating a first image of the source in the above-mentioned space at the input of the acceleration path at a fixed location on the beam axis.
  • the further electrode and the acceleration anode conjointly define a further lens for imaging the first image of the source.
  • Circuit means supplies to the further electrode a voltage whichis linearly porportional to the acceleration voltage and which is taken with reference to the potential on the acceleration anode.
  • the first image of the source is situated in the gap between the first anode and the further electrode, and preferably in the center of this gap, a lens effect of this gap is largely neutralized.
  • a possible lens effect of this gap' can be reduced further by applying to the further electrode a potential which is approximately equal to the potential of thefirst anode.
  • the first-anode voltage only voltages which are of the order of a few kV can then occur between the elec-
  • a field emission cathode in thenarrower sense is generally understood to be a cathode which is operated cold and in which the emission of the electrons-is caused by the strong electric field existing at the surface.
  • cathodes with a field that draws away and which are heated in addition are also known. The invention can be applied to advantage also in connection with this mixed-type of cathode.
  • FIG. 1 is a schematic diagram, partially in section, of an electron-beam illuminating system according to a preferred embodiment of the invention.
  • an electrostatic auxiliary lens is provided for imaging the electron source in the space between the first anode and the further electrode.
  • FIG. 2 illustrates an alternate embodiment of the electron-beam illuminating system of the invention wherein the auxiliary lens is configured as an electromagnetic lens.
  • the field-emission cathode is designated with reference numeral 1, the first anode with 2 and the accelerating anode with 3.
  • the potentials of these electrodes are U,, U and U respectively.
  • the accelerating anode 3 is at ground potential (U).
  • the upper part of the first anode 2 constitutes an auxiliary lens.
  • the auxiliary lens is an electrostatic einzel lens 2a equipped with the center electrode 4. Between the first anode 2 and the accelerating anode 3, a further electrode 5 is provided.
  • a high accelerating voltage V is provided by acceleration voltage supply means in the form of a highvoltage generator 6 and is applied to the field-emission cathode 1.
  • the first anode 2 has a positive voltage V which is taken from a voltage generator 7, relative to the field emission cathode 1.
  • V 5 kV and therefore, U 95 kV it is assumed that V 5 kV and therefore, U 95 kV.
  • the center electrode 4 of the einzel lens has, relative to the cathode 1, a voltage which is linearly proportional to the voltage V which draws the electrons; this voltage V is taken off at the potentiometer 8.
  • the potential U, of the center electrode is assumed to be 99 kV.
  • the einzel lens 2a, 4 projects at 9 a first image of the .electron source constituted by the cathode 1.
  • the first image 9 of the source is caused to remain at the same place independent of the voltage V
  • the voltage V can be varied at will for the purpose of controlling the emission.
  • the potential U of the further electrode 5 is adjusted by means of the potentiometer 10 so that it is linearly proportional to the accelerating voltage V
  • the further electrode and the accelerating electrode 3 conjointly form an electrostatic lens which images the image 9 at location 12.
  • the system is configured and the voltages selected with reference to each other such that the image 9 of the source is situated in the space 1] between the first anode 2 and the further electrode 5. Indeed, the image 9 is situated as nearly as possible in'the center of this gap.
  • the potential U of the further electrode 5 can in principle be chosen largely at will, for instance, 0.5 V in such a case, the electrodes 2 and 5 form a lens which, however, remains largely without effect, because the rays cross at 9 in the center of this lens.
  • a lens effect of the gap 11 can be suppressed still further if a potential which closely corresponds with the potential of the first anode 2 is applied to the electrode 5. This case is assumed in the illustrated embodiment and U is therefore about 0.95 V that is, 95 kV.
  • the voltage between the electrodes 2 and 5 can become no more than a few kV if the voltage V changes, so that the gap 11 constitutes only a weak lens.
  • the excitation of the lens 3, 5 is linearly proportional to the accelerating voltage V the location of the image 12, that is, the image distance of the illuminating system, remains practically constant if the accelerating voltages V change, so that a readjustment of the second imaging lens is not necessary.
  • a magnetic lens is provided as the auxiliary lens; all other parts are the same as in FIG. 1.
  • the magnetic auxiliary lens comprises the' iron enclosure 15 and the winding 16; the iron enclosure forms part of the first anode 2.
  • the winding 16 is supplied with an excitation current 1 ⁇ . taken from the regulated current source 17.
  • Reference numeral 19 is a computing element which furnishes an output voltage proportional to the square root of the voltage V
  • a voltage proportional to the current i is taken off at the resistor 18.
  • a comparator 20 compares these voltages with each other and changes the current i by adjusting the current source 17 so that the difference of the voltages vanishes.
  • An electron-beam illuminating system for an electrical apparatus such as an electron microscope comprising a cathode constituting a source for supplying the electron making up the electron beam;
  • first anode disposed adjacent said cathode and defining therewith a beam axis extending in the beam direction first anode voltage supply means for supplying a positive bias voltage to said first anode for determining the emission of said cathode;
  • an acceleration anode disposed beyond said first anode along the beam axis and defining an acceleration path for the electrons emitted by said cathode;
  • acceleration voltage supply means for establishing an acceleration voltage across said cathode and said accelerating anode
  • a further electrode disposed between said first anode and said acceleration anode, said further electrode and said first anode conjointly defining a space therebetween along the'beam axis;
  • an auxiliary lens disposed along the beam axis between said cathode and said acceleration anode for generating a first image. of said source in said space at the input of said acceleration path at a fixed location along the beam axis, said further electrode and said acceleration anode conjointly defining a further lens for imaging said first image of saidsource;
  • circuit means for supplying to said further electrode a voltage linearly proportional to said acceleration voltage and taken with reference to the potential on said acceleration anode.
  • circuit means including means for adjusting said voltage on said further electrode.
  • auxiliary lens being a electrostatic einzel lens having a center electrode; and auxiliary lens circuit means for supplying a voltage to said central electrode taken with respect to the voltage on said cathode and being linearly proportional to said positive bias voltage supplied to said first anode.
  • auxiliary lens being an electromagnetic lens having an excitation winding; and excitation winding supply means for supplying an excitation current to said excitation winding having a value proportional to a root of said positive bias voltage supplied to said first anode.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)
US373415A 1972-07-10 1973-06-25 Electron-beam illuminating system for an electrical apparatus such as an electron microscope or the like Expired - Lifetime US3862419A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2234381A DE2234381C3 (de) 1972-07-10 1972-07-10 Elektronenstrahl-Beleuchtungssystem

Publications (1)

Publication Number Publication Date
US3862419A true US3862419A (en) 1975-01-21

Family

ID=5850513

Family Applications (1)

Application Number Title Priority Date Filing Date
US373415A Expired - Lifetime US3862419A (en) 1972-07-10 1973-06-25 Electron-beam illuminating system for an electrical apparatus such as an electron microscope or the like

Country Status (5)

Country Link
US (1) US3862419A (hu)
JP (1) JPS5429075B2 (hu)
DE (1) DE2234381C3 (hu)
GB (1) GB1444098A (hu)
NL (1) NL7309348A (hu)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2527383A1 (fr) * 1982-05-24 1983-11-25 Univ Reims Champagne Ardenne Canon a electrons avec cathode a emission de champ et lentille magnetique
US20040208280A1 (en) * 2002-10-17 2004-10-21 Keiji Yada X-ray microscopic inspection apparatus
US20050111624A1 (en) * 2003-11-21 2005-05-26 Keiji Yada X-ray microscopic inspection apparatus

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3204897A1 (de) * 1982-02-12 1983-08-25 Siemens AG, 1000 Berlin und 8000 München Korpuskularstrahlerzeugendes system und verfahren zu seinem betrieb
US4426583A (en) * 1982-05-10 1984-01-17 International Business Machines Corporation Electron beam potential switching apparatus
JPH0619960B2 (ja) * 1986-12-27 1994-03-16 日本電子株式会社 熱電界放射型電子源を有した電子線装置
GB2215907B (en) * 1987-07-14 1992-04-15 Jeol Ltd Apparatus using a charged-particle beam

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678333A (en) * 1970-06-15 1972-07-18 American Optical Corp Field emission electron gun utilizing means for protecting the field emission tip from high voltage discharges

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS494972A (hu) * 1972-04-26 1974-01-17

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3678333A (en) * 1970-06-15 1972-07-18 American Optical Corp Field emission electron gun utilizing means for protecting the field emission tip from high voltage discharges

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2527383A1 (fr) * 1982-05-24 1983-11-25 Univ Reims Champagne Ardenne Canon a electrons avec cathode a emission de champ et lentille magnetique
EP0095969A1 (fr) * 1982-05-24 1983-12-07 Universite De Reims Champagne Ardenne Canon à électrons avec cathode à émission de champ et lentille magnétique
US4544845A (en) * 1982-05-24 1985-10-01 University de Reims Champagne Ardenne Electron gun with a field emission cathode and a magnetic lens
US20040208280A1 (en) * 2002-10-17 2004-10-21 Keiji Yada X-ray microscopic inspection apparatus
US7221731B2 (en) * 2002-10-17 2007-05-22 Tohken Co., Ltd. X-ray microscopic inspection apparatus
US20050111624A1 (en) * 2003-11-21 2005-05-26 Keiji Yada X-ray microscopic inspection apparatus

Also Published As

Publication number Publication date
GB1444098A (en) 1976-07-28
DE2234381B2 (de) 1975-02-27
JPS4946670A (hu) 1974-05-04
DE2234381C3 (de) 1975-10-16
JPS5429075B2 (hu) 1979-09-20
DE2234381A1 (de) 1974-01-31
NL7309348A (hu) 1974-01-14

Similar Documents

Publication Publication Date Title
JP4759113B2 (ja) 荷電粒子ビームカラム
US2219193A (en) Cathode ray apparatus
US3862419A (en) Electron-beam illuminating system for an electrical apparatus such as an electron microscope or the like
US3576438A (en) Focus monitor for electron microscope including an auxiliary electron gun and focusing lens
US2260041A (en) Electron microscope
US4467205A (en) Highly-steady beam generating for charged particles
US5895919A (en) Gun lens for generating a particle beam
US4110622A (en) Device which makes it possible to effect the programmed tracing of figures which have different shapes
US3225248A (en) Device for producing a high-intensity beam of charge carriers of small aperture
GB828224A (en) High-compression beam generating system for velocity-modulated tubes
US3786305A (en) Field emission electron gun
US2354263A (en) Electron microscope
US2412086A (en) Image dissector tube
US4020387A (en) Field emission electron gun
US3925706A (en) Field emission electron gun device of the automatic control type
US4500791A (en) High stability electron beam generator for processing material
US3931519A (en) Field emission electron gun
EP0031679B1 (en) Vidicon type camera tube
US3731094A (en) Electron beam apparatus with means for generating a rotation-symmetrical magnetic field
US3931517A (en) Field emission electron gun
US2905854A (en) Electron-discharge device
US3551671A (en) Ion-electron image converter for use with ion microanalyzers
US4201933A (en) Electron gun structure for a pickup tube
US2632115A (en) Focusing device for electron microscopes
US2835838A (en) Cathode-ray tube