US3842271A - Scanning electron microscope - Google Patents

Scanning electron microscope Download PDF

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Publication number
US3842271A
US3842271A US00354039A US35403973A US3842271A US 3842271 A US3842271 A US 3842271A US 00354039 A US00354039 A US 00354039A US 35403973 A US35403973 A US 35403973A US 3842271 A US3842271 A US 3842271A
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United States
Prior art keywords
glass
specimen
light
combination according
scanning electron
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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
US00354039A
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English (en)
Inventor
A Gee
E Snitzer
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.)
Nanometrics Inc
Original Assignee
American Optical Corp
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 American Optical Corp filed Critical American Optical Corp
Priority to US00354039A priority Critical patent/US3842271A/en
Priority to DE2417319A priority patent/DE2417319A1/de
Priority to AU67633/74A priority patent/AU474023B2/en
Priority to NL7405307A priority patent/NL7405307A/xx
Priority to FR7415642A priority patent/FR2227632B1/fr
Priority to DD178043A priority patent/DD113660A5/xx
Priority to SE7405430A priority patent/SE388721B/xx
Priority to CA197,992A priority patent/CA1006990A/en
Priority to JP49045152A priority patent/JPS5014273A/ja
Priority to IT50584/74A priority patent/IT1004276B/it
Priority to GB1797674A priority patent/GB1436278A/en
Application granted granted Critical
Publication of US3842271A publication Critical patent/US3842271A/en
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 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 NANOMETRICS, INC. reassignment NANOMETRICS, INC. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: WARNER LAMBERT TECHNOLOGIES, INC.,
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H01J37/244—Detectors; Associated components or circuits therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/20—Measuring radiation intensity with scintillation detectors
    • G01T1/202—Measuring radiation intensity with scintillation detectors the detector being a crystal
    • 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
    • H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
    • H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2443—Scintillation detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2445—Photon detectors for X-rays, light, e.g. photomultipliers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2448—Secondary particle detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2449—Detector devices with moving charges in electric or magnetic fields
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/245—Detection characterised by the variable being measured
    • H01J2237/24507—Intensity, dose or other characteristics of particle beams or electromagnetic radiation

Definitions

  • This invention relates generally to improvements in scanning microscopes and more particularly to a scanning electron microscope having a glass scintillating element capable of providing substantially longer service life than previous scintillating elements and giving a fluorescence of high intensity and short decay time when bombarded with electrons.
  • the scanning electron microscope including such a glass scintillator may be either of the thermionic (hot cathode) type or the field emission (cold cathode) type.
  • Present-day scanning electron microscope systems include an electron gun (either cold or hot cathodes) providing a source of electrons which are accelerated and focused by anode means disposed downstream from the electron source. These anodes form the supply of electrons into a beam which is directed to bombard a specimen disposed further downstream from the source than the accelerating and focusing anodes.
  • the bombarded specimen under the influence of the high energy electrons striking its surface, emits secondary electrons, the number of which carry information of the physical character of the specimen being bombarded. These secondary electrons are accelerated and directed to bombard a scintillation device.
  • the scintillator produces a light upon bombardment by the electrons, the intensity of which varies according to the number of the electronsstriking the scintillator.
  • This luminescence of the scintillator is transmitted to a photo-multiplier or other photon detecting device which, in turn, generates an electrical signal approximately proportional to the light signal sensed by it.
  • the electrical signal output of the photo-multiplier may then be displayed as on a cathode ray tube to reveal the information carried by the emitted secondary electrons.
  • the electron beam is caused to scan the specimen in a longitudinal and lateral pattern similar to conventional television picture generation and a television-type monitor is used to display the signal of the photo-multiplier.
  • the signal of the photo-multiplier is utilized as a brightness control for the cathode ray of the television-type monitor and the sweep of that monitor is synchronized to the sweep of the electron beam across the specimen.
  • the picture displayed on the monitor provides a physical representation of the secondary electron emission across the scanned surface of the specimen.
  • Thermionic electron microscopes have been known for many years and have become highly developed. With the advent of the scanning mode of operation in thermionic electron microscopes, a new dimension in specimen examination was achieved. The electron beam could be traced across the surface of the specimen and the secondary emission detected and recorded to give a detailed indication of the structure of the specimen at its surface. Certain problems were encountered in providing a usable output from such devices. The beam first had to be concentrated into a finely focused spot on the face of the specimen and then caused to track across its surface in the usual longitudinal and lateral pattern. In the high focusing or demagnification of the electron beam into a small spot the beam current may be reduced to a very low level causing the population of the secondary emission to be somewhat less than desired. However, the encountered problems were technical ones which were overcome by diligent effort in view of the significant advantages gained by the scanning electron microscope and, principally, the more detailed information available regarding the surface character of the specimen.
  • This type includes a cold cathode or a field emission tip as the electron source.
  • This high brightness field emission tip has proved to be a much more productive source of electrons, such that beam currents as measured at the focused spot on the specimen can be as much as 1,000 times greater than those experienced with conventional scanning electron microscopes (10 amps as compared to 10 amps in thermionic devices).
  • the increased beam current at the specimen has greatly-increased the secondary electron emission and enabled a much faster scanning mode of operation which further contributes to greater contrast in the viewed secondary emission pattern as displayed on monitored devices.
  • the many fold increase in beam and secondary emission currents has disclosed weaknesses in the scintillating devices previously used.
  • Scintillating devices 'used in thermionic scanning electron microscopes and in the early days of field emission electron microscopes are commonly composed of organic fluorescing material, either coated on or dissolved in plastics (such as plexiglas).
  • a common source of scintillating devices for such machines is the Pilot Chemicals, Inc. of Watertown, Massgand a common material being the Pilot B scintillator material.
  • These common plastics may be further coated or brushed with fluorescing material.
  • the low current density of electron bombardment caused no problematical rapid deterioration of the scintillating elements.
  • the scintillating devices such as the organic fluorescers were utilized in the field emission scanning devices having high beam currents (typically l nano amp as compared to l pico amp for the thermionic device, for example) the scintillating devices showed significant deterioration after a service life of only a few hours. Naturally, a requirement of changing'the scintillating device as often as once a day or perhaps several times a week was highly undesirable.
  • the known glass scintillators were generally alkali silicate glass including in particular the alkali constituent'lithium. We have found that the presence of the alkalis contributes to the degradation of the lighttransmitting properties of such glass when bombarded by electrons at beam currents of the order used in field emission scanning electron microscopes. This problem is generally identified as solarization and results in the glass taking on a darkening or browning.
  • silicate glasses revealed inordinate numbers of dis continuities', inclusions, flaws, etc., all of which significantly detract from the optical-transmitting capability. While the optical quality of these glasses might be improved some, the poor quality of the observed samples does not suggest that anything approaching true optical'quality could be achieved. Physical examination of these materials tends to convince one that they would be unacceptable as a scintillating device for electron detection in the electron microscope application.
  • the pure silicate glasses are so difficult to produce and so difficult to dope with luminescent-promoting materials, such as rare earth oxides, that their resulting structure is full of the previously-mentioned inclusions, discontinuities, flaws, etc. and their resulting poor optical properties suggest unacceptability as a light generator and transmitter.
  • the tri-valent cerium doped material is formed into the shape of a conventional scanning electron microscope scintillator (a hemisphere) and disposed on the end of a glass light pipe (which also is compatible with the refractive index of the glass scintillator) a long life responsive scintillating element for scanning electron microscopy is produced.
  • the present invention is directed to the combination of a scanning electron microscope and a glass scintillator.
  • an alkali-free glass scintillating device having a cerium oxide dopant is disposed on a glass light pipe with an optical quality adhesiveand coupled with a photo-multiplier device is incorporated in the specimen chamber of a scanning electron microscope.
  • reference numeral 10 indicates a scanning electron microscope which embodies the present invention.
  • the illustrated microscope 10 is of the field emission type wherein a cold field emission tip 12 disposed in a gun chamber 14 maintained in ultra-high vacuum (in the order of 10 Torr.) serves as the source of electrons.
  • US. Pat. No. 3,678,333 is illustrative of a field emission tip type of scanning electron microscope.
  • the illustration of the present invention in combination with the-field emission type microscope is by way of illustration and not by way of limitation, for the invention might be embodied equally wellin a scanning electron microscope having a thermionic electron source.
  • These later devices include a hot cathode generally in the form of a hairpin-shaped tungsten filament disposed within the influence of a grid usually called a Wehnelt cylinder.
  • a first anode 16 of a focusing electrode 18 is formed in an annular shape with a central opening 20. Spaced downstream from the first anode 16 is a second' anode 22 (afocusing electrode) having a centralmore positive with respect to tip 12 than the voltage applied to first anode 16.
  • the beam 26 is thus influenced by anode 22 to further accelerate the electrons of beam 26 focusing them as well, to subsequently cause them to impinge upon the surface of a specimen S disposed in specimen chamber 30.
  • Chamber 30 is a vacuum holding chamber, similar to gun chamber 14, however operable at less vacuum (in the order of 10' Torr.) Chamber 30 is isolated from gun chamber 14 by means of walls 32 and includes a central aperture 34. Valving means for sealing aperture 34 to facilitate changing of specimen S is described in the aforementioned US Pat. No. 3,678,333.
  • Beam 26 after leaving anode 22 and prior to reaching specimen S, passes between deflection means 36 and laterally of its surface in the familiar rectangular scan pattern.
  • secondary electrons are emitted from the specimen at the bombarded point, the amount of secondary electrons being variable and generally depending upon the material of the particular bombarded point in the incident angle of the electron beam 26.
  • primary electrons of beam 26 may be reflected from the surface of specimen S and co-mingled with the secondary electrons, these reflected primary electrons being known as back scattered electrons.
  • the secondary electrons emitted from specimen S are usually of substantially lower energy level than the primary electrons rendering them discernable from the back-scattered electrons.
  • the number and energy. of the secondary emissions contains information as to the character of the surface of specimen S.
  • Scintillator 42 is a device which is responsive to bombardment of corpuscular radiation (such asby positive or negative ions or electrons) providing a luminescence in response thereto.
  • Scintillator 42 includes a fluorescent tip 46 fixedly secured to a light pipe 48 which, in turn, is operably connected to photo-multiplier 44.
  • the tip luminesces with a light signal whose amplitude is generally proportional to the number and energy of electrons bombarding the tip.
  • the luminescence is transmitted from the tip through light tube 48 to a photo-multiplier 44 which, in turn, generatesan electrical signal proportional to the luminescence of tip 46.
  • This electrical signal of photo-multiplier 44 is then supplied through amplifying means 50 to a display such as television monitor 52.
  • Scanning control 38 is also operably connected to television monitor 52 to synchronize the monitor to the scan of electron beam 36 so that the observed secondary emission of specimen S can be displayed across the face of the television monitor 52.
  • FIG. 2 an enlarged view of the scintillating device 42 for utilization in a scanning electron microscope is shown.
  • a mounting plate 60 adapted to be disposed on specimen chamber 30 is fitted with suitable sealing means such as the illustrated O-rings 62 for maintaining the previously-mentioned vacuum in said specimen chamber.
  • suitable sealing means 62 are disposed within the aperture 64 to coact with light pipe 48 to maintain the desired vacuum in chamber 30.
  • Disposed internally of chamber 30 at the end of light pipe 48 is glass scintillating tip 46. It is fixedly secured on the end of pipe 48 with a transparent adhesive having properties of good light conduction,
  • an adhesive coupling for tip 46 to pipe 48 is a mechanical coupling, suchas aclip or the like. These mechanical couplings, however, do not ensure a positive contact across the interfacing surfaces and thus permit loss or attenuation of the transmitted light signal;
  • Light pipe 48 is constructed of a glass material of compatible transmission characteristics to the host glass of tip 46 (e.g., of similar index of refraction) to insure maximum transmission of light across the interface.
  • core glass commercially available under the name Schott BaF Type 4 has been found satisfactory.
  • the glass pipe in the preferred embodiment is similar to a light-conducting glass fiber however having dimensions substantially greater.
  • the pipe has a diameter of approximately three-eighths inches and is of the clad type wherein an outer reflecting layer of substantially lower refractive index glass is disposed over a lightconducting core.
  • the cladding Kimble Type EN-l has been found satisfactory.
  • Tip 46 in one embodiment, is'constructed of a high purity silicate glass doped with a cerium oxide with the active fluorescing ion being Ce.
  • Thematerial for the tip may be generally prepared (doped) with'the chosen cerium material according to the methods disclosed in the HS. Pat. No. 3,527,71 1.
  • Tip 46 is generally ground and polished to a hemispherical shape having a radius of about three-sixteenths inches and disposed on the end of the light pipe having a similar radius.
  • the glass must be resistant to degradation due to bombardment of electrons (solarization) and be able to withstand high vacuum (about 10" Torr.) and heat (about 200C). Further, the glass must be able to be doped with cerium oxide to a sufficient extent to efficiently fluoresce when bombarded with electrons. For use in fast scanning electron microscopes, it has been found that the fluorescence of the scintillator must be of comparatively short duration (less than 100 nano seconds) to provide a resolution compatible with the characteristics of the fast scan of the field emission type of scanning electron microscope. Thus, the host and dopant-must exhibit a combined influence upon each other to present the aboverequired characteristics.
  • grid voltage in the order of l volts to +300 volts may be applied to grid cap 66.
  • This voltage may either reject or accelerate the emitted secondary electrons from the surface of specimen S toward scintillator 42. In the instance when the secondary electrons are rejected, the scintillator may detect the backscattered electrons.
  • the bias voltage in the order of 10 volts is applied to tip 46 to maximize the capture 0f electrons on the hemispherical tip at its apex.
  • the striking of the secondary electrons on the scintillator tip 46 generates a luminescence proportional to the number of electrons striking the tip which is conveyed by the light pipe 48 to photomultiplier tube 44.
  • the light signal is converted to an electrical signal proportional to the varying intensity of the light generated by the secondary electrons.
  • This electrical signal is conditioned (amplified, etc.) to serve as brightness input of the cathode ray within television monitor 52.
  • said glass light-transmitting means is a glass-light conducting core clad with a glass shell having a refractive index lower than the refractive index of'said core.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Measurement Of Radiation (AREA)
US00354039A 1973-04-24 1973-04-24 Scanning electron microscope Expired - Lifetime US3842271A (en)

Priority Applications (11)

Application Number Priority Date Filing Date Title
US00354039A US3842271A (en) 1973-04-24 1973-04-24 Scanning electron microscope
DE2417319A DE2417319A1 (de) 1973-04-24 1974-04-05 Elektronisches abtastmikroskop
AU67633/74A AU474023B2 (en) 1973-04-24 1974-04-08 Scanning electron microscope
NL7405307A NL7405307A (xx) 1973-04-24 1974-04-19
DD178043A DD113660A5 (xx) 1973-04-24 1974-04-22
FR7415642A FR2227632B1 (xx) 1973-04-24 1974-04-22
SE7405430A SE388721B (sv) 1973-04-24 1974-04-23 Anordning vid ett svepelektronmikroskop
CA197,992A CA1006990A (en) 1973-04-24 1974-04-23 Scanning electron microscope
JP49045152A JPS5014273A (xx) 1973-04-24 1974-04-23
IT50584/74A IT1004276B (it) 1973-04-24 1974-04-23 Perfezionamento nei microscopi elettronici a scansione
GB1797674A GB1436278A (en) 1973-04-24 1974-04-24 Scanning electron microscopes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00354039A US3842271A (en) 1973-04-24 1973-04-24 Scanning electron microscope

Publications (1)

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US3842271A true US3842271A (en) 1974-10-15

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US00354039A Expired - Lifetime US3842271A (en) 1973-04-24 1973-04-24 Scanning electron microscope

Country Status (11)

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US (1) US3842271A (xx)
JP (1) JPS5014273A (xx)
AU (1) AU474023B2 (xx)
CA (1) CA1006990A (xx)
DD (1) DD113660A5 (xx)
DE (1) DE2417319A1 (xx)
FR (1) FR2227632B1 (xx)
GB (1) GB1436278A (xx)
IT (1) IT1004276B (xx)
NL (1) NL7405307A (xx)
SE (1) SE388721B (xx)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0018031A2 (en) * 1979-04-13 1980-10-29 Koninklijke Philips Electronics N.V. Detector for an electron microscope
US4992662A (en) * 1986-08-01 1991-02-12 Electroscan Corporation Multipurpose gaseous detector device for electron microscope
EP0443410A2 (en) * 1990-02-23 1991-08-28 International Business Machines Corporation Multiple detector system for specimen inspection using high energy backscatter electrons
US5142148A (en) * 1989-03-30 1992-08-25 Hitachi, Ltd. Field emission scanning electron microscope and method of controlling beam aperture angle
EP1365260A1 (en) * 2001-01-31 2003-11-26 Hamamatsu Photonics K.K. Electron beam detector, scanning type electron microscope, mass spectrometer, and ion detector
US6693282B1 (en) * 1999-06-22 2004-02-17 Fei Company Particle-optical apparatus including a particle source that can be switched between high brightness and large beam current
EP2088614A1 (en) * 2008-02-08 2009-08-12 ICT, Integrated Circuit Testing Gesellschaft für Halbleiterprüftechnik Mbh Beam current calibration system
US20150155133A1 (en) * 2013-03-25 2015-06-04 Hermes Microvision Inc. Charged Particle Beam Apparatus
US20170016995A1 (en) * 2015-07-19 2017-01-19 Afo Research, Inc. Fluorine resistant, radiation resistant, and radiation detection glass systems
US10236156B2 (en) 2015-03-25 2019-03-19 Hermes Microvision Inc. Apparatus of plural charged-particle beams

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3052637A (en) * 1961-06-05 1962-09-04 Adli M Bishay Glass composition and process of making
US3472997A (en) * 1966-08-26 1969-10-14 Us Navy Secondary electron collection system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3052637A (en) * 1961-06-05 1962-09-04 Adli M Bishay Glass composition and process of making
US3472997A (en) * 1966-08-26 1969-10-14 Us Navy Secondary electron collection system

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0018031A2 (en) * 1979-04-13 1980-10-29 Koninklijke Philips Electronics N.V. Detector for an electron microscope
EP0018031A3 (en) * 1979-04-13 1980-11-12 N.V. Philips' Gloeilampenfabrieken Detector for an electron microscope
US4992662A (en) * 1986-08-01 1991-02-12 Electroscan Corporation Multipurpose gaseous detector device for electron microscope
US5142148A (en) * 1989-03-30 1992-08-25 Hitachi, Ltd. Field emission scanning electron microscope and method of controlling beam aperture angle
EP0443410A2 (en) * 1990-02-23 1991-08-28 International Business Machines Corporation Multiple detector system for specimen inspection using high energy backscatter electrons
EP0443410A3 (en) * 1990-02-23 1991-11-13 International Business Machines Corporation Multiple detector system for specimen inspection using high energy backscatter electrons
US6693282B1 (en) * 1999-06-22 2004-02-17 Fei Company Particle-optical apparatus including a particle source that can be switched between high brightness and large beam current
EP1365260A1 (en) * 2001-01-31 2003-11-26 Hamamatsu Photonics K.K. Electron beam detector, scanning type electron microscope, mass spectrometer, and ion detector
EP1365260A4 (en) * 2001-01-31 2013-01-23 Hamamatsu Photonics Kk ELECTRON BEAM DETECTOR, RASTER ELECTRONIC MICROSCOPE, MASS SPECTROMETER AND ION DETECTOR
US7982179B2 (en) 2008-02-08 2011-07-19 ICT Intergrated Circuit Testing Gesellschaft für Halbeiterprüftechnik mbH Beam current calibration system
US20090200497A1 (en) * 2008-02-08 2009-08-13 Ict Integrated Circuit Testing Gesellschaft Fur Halbleiterpruftechnik Mbh Beam current calibration system
EP2088614A1 (en) * 2008-02-08 2009-08-12 ICT, Integrated Circuit Testing Gesellschaft für Halbleiterprüftechnik Mbh Beam current calibration system
US20150155133A1 (en) * 2013-03-25 2015-06-04 Hermes Microvision Inc. Charged Particle Beam Apparatus
US9362087B2 (en) * 2013-03-25 2016-06-07 Hermes Microvision, Inc. Charged particle beam apparatus
US10020164B2 (en) 2013-03-25 2018-07-10 Hermes Microvision Inc. Charged particle beam apparatus
US10236156B2 (en) 2015-03-25 2019-03-19 Hermes Microvision Inc. Apparatus of plural charged-particle beams
US11217423B2 (en) 2015-03-25 2022-01-04 Asml Netherlands B.V. Apparatus of plural charged-particle beams
US20170016995A1 (en) * 2015-07-19 2017-01-19 Afo Research, Inc. Fluorine resistant, radiation resistant, and radiation detection glass systems
WO2017015176A1 (en) * 2015-07-19 2017-01-26 Afo Research, Inc Fluorine resistant, radiation resistant, and radiation detection glass systems
US10393887B2 (en) * 2015-07-19 2019-08-27 Afo Research, Inc. Fluorine resistant, radiation resistant, and radiation detection glass systems

Also Published As

Publication number Publication date
CA1006990A (en) 1977-03-15
IT1004276B (it) 1976-07-10
DE2417319A1 (de) 1974-11-07
AU474023B2 (en) 1976-07-08
FR2227632A1 (xx) 1974-11-22
SE388721B (sv) 1976-10-11
JPS5014273A (xx) 1975-02-14
GB1436278A (en) 1976-05-19
AU6763374A (en) 1975-10-09
DD113660A5 (xx) 1975-06-12
NL7405307A (xx) 1974-10-28
FR2227632B1 (xx) 1978-03-31

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

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:AMERICAN OPTICAL CORPORATION;REEL/FRAME:004034/0688

Effective date: 19820513

Owner name: WARNER LAMBERT TECHNOLOGIES, INC., 6373 STEMMONS F

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

Effective date: 19820514

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