WO2003036677A1 - Microscope electronique dote d'un spectrometre a rayons x - Google Patents

Microscope electronique dote d'un spectrometre a rayons x Download PDF

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Publication number
WO2003036677A1
WO2003036677A1 PCT/JP2002/001899 JP0201899W WO03036677A1 WO 2003036677 A1 WO2003036677 A1 WO 2003036677A1 JP 0201899 W JP0201899 W JP 0201899W WO 03036677 A1 WO03036677 A1 WO 03036677A1
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WO
WIPO (PCT)
Prior art keywords
ray
diffraction grating
electron microscope
microscope according
sample
Prior art date
Application number
PCT/JP2002/001899
Other languages
English (en)
Japanese (ja)
Inventor
Masami Terauchi
Original Assignee
Jeol Ltd.
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
Priority claimed from JP2001326066A external-priority patent/JP2002329473A/ja
Application filed by Jeol Ltd. filed Critical Jeol Ltd.
Publication of WO2003036677A1 publication Critical patent/WO2003036677A1/fr

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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
    • H01J37/244—Detectors; Associated components or circuits therefor
    • 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
    • H01J37/252—Tubes for spot-analysing by electron or ion beams; Microanalysers
    • H01J37/256—Tubes for spot-analysing by electron or ion beams; Microanalysers using 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
    • H01J2237/2445—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
    • H01J2237/2446—Position sensitive detectors

Definitions

  • the present invention relates to an electron microscope equipped with an X-ray spectroscope. Background art
  • a wavelength-dispersive spectrometer is attached to a scanning electron microscope (SEM), and the characteristic X-rays generated when the sample is irradiated with an electron beam in the electron microscope are detected by the WDS.
  • An electron probe microanalyzer (EPMA) for performing line analysis (elemental analysis) is known.
  • This WDS requires a mechanism that aligns the three points of the X-ray generation point (sample), the center point of the spectral crystal, and the center point of the slit of the detector with predetermined positions on the Rowland circle. Because it is several meters long, it becomes a large-scale optical system.
  • an energy dispersive spectrometer (EDS) is combined with a transmission electron microscope (T EM) or SEM to detect characteristic X-rays from a sample by EDS.
  • EDS energy dispersive spectrometer
  • T EM transmission electron microscope
  • SEM SEM
  • the present inventor has been developing an electron microscope capable of performing high-resolution energy analysis by combining an energy filter with a transmission electron microscope (TEM). Using this device, it is possible to know the dielectric function and the conduction band density distribution in the 30 nm ⁇ region of the sample. For detailed electronic state studies It is necessary to know not only the conduction band but also the valence band state density. As described above, in a transmission electron microscope (TEM) equipped with an EDS, elemental analysis can be performed using characteristic X-rays generated from a region irradiated with an electron beam. If Torr can be measured with an energy resolution of less than leV, the valence band density of states distribution can be obtained.
  • TEM transmission electron microscope
  • the energy resolution of current EDS using semiconductor detectors is about 100-200 eV, which is not enough for studying electronic states.
  • WDS has a higher resolution (about 10 eV) than EDS, but does not have sufficient energy resolution to obtain the valence band state density. Disclosure of the invention
  • An object of the present invention is to provide an electron microscope having an X-ray spectrometer having a compact optical system and capable of obtaining high energy resolution.
  • An electron microscope equipped with the X-ray spectrometer of the present invention is an X-ray spectrometer which is evacuated by a vacuum pump, has a non-equidistant diffraction grating, and has a spectroscopic chamber having an X-ray detector attached to an end. Electron microscope attached to the side wall of an electron microscope via a gate valve. The characteristic X-ray emitted from the sample irradiated with the electron beam is oblique at a large angle with respect to the normal to the irregularly spaced diffraction grating surface. The X-ray detector detects the diffracted X-rays with an X-ray detector.
  • the X-ray detector a back-illuminated CCD detector can be used. It is preferable that the emission angle of the X-ray diffracted by the unequally spaced diffraction grating is 75 to 87 degrees with respect to the normal to the diffraction grating surface.
  • the characteristic X-rays emitted from the sample are focused toward the irregularly spaced diffraction grating.
  • An X-ray focusing mirror can be provided.
  • the CCD detector is connected to the spectroscopic chamber via a bellows so as to be movable with respect to the diffraction grating.
  • the bellows has a structure in which a plurality of bellows with different expansion and contraction directions are connected in cascade, and the CCD detector can be moved two-dimensionally with respect to the diffraction grating by combining expansion and contraction of multiple bellows. It is preferably provided in BRIEF DESCRIPTION OF THE FIGURES
  • FIG. 1 is a diagram showing an example of a transmission electron microscope equipped with an X-ray spectrometer.
  • FIG. 3 is a conceptual diagram illustrating another example of the transmission electron microscope of the present invention.
  • FIG. 4 is a diagram showing an X-ray focusing mirror.
  • FIG. 5 is a diagram showing a grating exchange mechanism.
  • FIG. 6 is a diagram showing a grating tilt adjusting mechanism.
  • FIG. 7 is a diagram showing another example of the X-ray focusing mirror. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 shows an example of a transmission electron microscope equipped with an X-ray spectrometer according to the present invention.
  • FIG. 1 the inside of the lens barrel 2 of the TEM 1 is maintained at a vacuum.
  • the sample 3 placed in the lens barrel 2 is irradiated with an electron beam from above through an electron lens, and is projected on a fluorescent screen through an electron beam lens transmitted through the sample.
  • a transmitted electron image is formed on the phosphor screen.
  • a hole for taking out characteristic X-rays generated from the sample to the outside of the lens barrel 2 is formed in the side wall of the room in which the sample 3 of the lens barrel 2 is disposed, and a connection pipe having a gate valve 4 in this hole is provided.
  • X-ray spectroscope 10 is attached via 60.
  • the gate valve 4 is arranged between the spectroscope 10 and the lens barrel of the TEM 1 and can separate the vacuum of both.
  • Spectroscope (spectrometer chamber 1) 11 A diffraction grating 12 arranged in the chamber 1 and a back-illuminated CCD detector 14 attached to the end of the spectroscopic chamber via a bellows 13 14 Spectroscope 10 Is configured.
  • the diffraction grating 12 has grooves formed at irregular intervals for aberration correction. It is known that such unequally spaced diffraction gratings can realize an image plane perpendicular to the diffracted light when light is incident at a large incident angle. Therefore, in this embodiment, the characteristic X-ray emitted from the sample 3 when irradiated with the electron beam in the TEM 1 has a large incident angle ⁇ (normally parallel to the diffraction grating plane) with respect to the normal to the diffraction grating plane. ), The incident angle a to the diffraction grating is selected.
  • the focal point of the diffracted X-rays is created not on the Rowland circle but on a plane (CCD plane) almost perpendicular to the light rays. Dispersion due to this diffraction grating is smaller than that of a normal grooved diffraction grating, so that a wide energy range can be detected using a fixed CCD detector 14.
  • the spectrometer chamber 11 is provided with a turbo molecular pump (TMP) 19 and a sputter ion pump (SIP) 18 combined with a single pump 20 through valves 15, 16 and 17. It has been evacuated to a vacuum.
  • TMP turbo molecular pump
  • SIP sputter ion pump
  • the diffraction grating of the present embodiment has 1200 grooves / mm, and is arranged so that the interval gradually changes from one to the other along the traveling direction of the light beam (X-ray).
  • the diffraction grating has a concave surface with a radius of 6549 mm, a width (in the direction perpendicular to the light beam direction) of 30 mm, and a length (in the light beam direction) of 50 mm.
  • a gold layer is formed on the surface by surface treatment.
  • the incident angle ⁇ to the normal of the diffraction grating surface is 87 degrees
  • the emission angle 3 is 77 to 83 degrees
  • the length of the arm is , Are set to 237mm and 235mm respectively.
  • the back-illuminated CCD has a size of 1100X330 pixels, size 26.4mm x 7.9mm, and one pixel size of 24 ⁇ m x 24xm (resolution corresponding to an emission angle of 77 to 83 degrees).
  • the spot size of the diffracted X-ray focused on the CCD detector is the superposition of the size of the electron beam on the sample and the spread due to the aberration of the diffraction grating.
  • the size of the electron beam focused on the sample is approximately 500 ⁇ m in the experiment. It has been reported that the spot spread due to the diffraction grating aberration is 40 m at 248 eV and 20 ⁇ m at 124 eV, so the spread for Boron K emission energy of about 185 eV is almost It is estimated to be 30 / xm. Therefore, the spot size of the diffracted X-ray focused on the CCD detector is mainly determined by the aberration.
  • the energy resolution of the Boron K emission spectrum is estimated to be about 0.6 eV (0.3 eV x 2 pixels).
  • Figure 2 shows a Boron K emission spectrum of 3 pols obtained from a 600 nm diameter single crystal sample surface at a probe current of about 70 ⁇ A.
  • the detection time is about 1 hour.
  • the horizontal axis represents the number of channels of the CCD detector.
  • the stalls show one peak and two shoulders, each indicated by an arrow and a vertical line.
  • the energy of the peak is 185 eV and the width of the peak is about 10 eV when referring to the previously reported spectrum by the diffraction spectrometer.
  • FIG. 2 shows that the device of the present invention has a high energy resolution and an excellent SZN ratio.
  • FIG. 3 is a conceptual diagram illustrating another example of the transmission electron microscope of the present invention.
  • a hole is made to take out the characteristic X-rays generated from the sample to the outside of the lens barrel 2, and a metal connection pipe 6 is formed in this hole.
  • 0—1 is entered.
  • One end of the connection pipe 60-1 extends into the room toward the sample 3, and the other end is connected to the gate valve 4.
  • An X-ray spectroscope 10 is connected to the other end of the gate valve 4 via a metal connection pipe 60-2.
  • An X-ray focusing mirror 30 for collecting X-rays emitted from the sample 3 is mounted inside the distal end of the connection tube 60-1.
  • the X-ray focusing mirror 30 focuses the X-rays to increase the intensity of X-rays incident on the diffraction grating.
  • the fixed time can be shortened and the SZN ratio of the spectrum can be improved.
  • the collected X-rays are unequally spaced in the spectrometer chamber 11 through slits 31 and 32 arranged in the connecting pipes 60-1 and 60-2 before and after the gate valve 4. The light enters the diffraction grating 12.
  • Slits 33 are also arranged immediately above the incident surface of the unequally spaced diffraction grating 12 with a small distance from the incident surface (a distance that does not hinder X-ray incidence and emission).
  • the light emitted from the electron irradiation point on the sample and traveling in a direction other than the X-ray optical path from the sample to the diffraction grating reaches the CCD detector 14 by these multiple slits 31, 32, and 33. It can be prevented from being detected as a ground. This improves the S / N ratio of the spectrum.
  • the unequally spaced diffraction grating 12 is attached to a grating exchange mechanism 40 described later.
  • the grating exchange mechanism 40 holds and holds a plurality of unequally spaced diffraction gratings having different measurement energy regions.
  • One of the unequally spaced diffraction gratings is set at the X-ray incident position and diffracts X-rays.
  • the tilt of the diffraction grating set at the X-ray incident position is adjusted by the grating tilt adjusting mechanism 50.
  • a CCD detector 14 for detecting diffracted X-rays is attached to the end of the spectrometer chamber 11 via a bellows 13.
  • the spectrometer chamber 111 of the present embodiment includes two divided cylinders 111, 112 and a bellows 34 connecting the two cylinders. As shown in FIG. 3, the two cylinders 1 1—1, 1 1 and 1 2 are arranged with their center axes shifted, and the bellows 3 4 The cylinder 1 1 1 1 and 1 1-2 are connected. As a result, by combining the expansion and contraction of the two bellows 13 and 34, the CCD detector 14 can be moved up and down, left and right (two-dimensional direction), and the position can be finely adjusted.
  • the position and direction of the light receiving surface with respect to the diffracted X-rays are adjusted by moving the cylinder 1 1-2 and the CCD detector 14 using two bellows having different expansion and contraction directions. Can be.
  • the incidence of the diffracted X-rays on the CCD detector can be optimized by combining the adjustment of the grating inclination adjusting mechanism 50.
  • FIG. 4 is a diagram illustrating the X-ray focusing mirror 30.
  • the X-ray focusing mirror 30 is a pair of two mirrors facing each other, and the surface facing each mirror is flat in the direction perpendicular to the plane of the paper, and in the direction parallel to the plane of the paper, the angle of incidence of X-rays on the mirror gradually decreases.
  • a curved surface is drawn on the sample, and the distance between the mirrors is such that the sample side is narrow and the diffraction grating side is wide.
  • X-rays generated from the electron beam irradiation point of the sample tilted toward the X-ray focusing mirror are radiated in all solid angle directions, and XI and X2 in the figure (the electron beam irradiation point of the sample and the diffraction grating).
  • the range within the straight line connecting the ends) represents the X-rays incident on the diffraction grating when no mirror is used.
  • the X-rays in the range between XI and X3, X2 and X4 in the figure (X3 and X4 are straight lines connecting the sample and the front end of the mirror)
  • the light is condensed and enters the diffraction grating.
  • the intensity of X-rays incident on the diffraction grating increases (the solid angle of X-ray detection increases), so that the measurement time can be reduced and the SZN ratio of the spectrum can be improved.
  • FIG. 5 is a diagram illustrating an example of the grating exchange mechanism.
  • Fig. 5 (a) In the example, unequally spaced diffraction gratings I, II, and III having different measurement energy ranges are fixed to a rotating table 41 that can rotate in a vertical plane, and the rotation angle of the rotating table can be adjusted from outside the vacuum. As a result, any one of the three diffraction gratings can be set at the X-ray incident position by the slit 33 without breaking the vacuum. Of course, a turntable that rotates in a horizontal plane may be used.
  • unequally spaced diffraction gratings I, II, and II with different measurement energy ranges are fixed to the horizontal moving table 42, and the position of the horizontal moving table 42 is adjusted from outside the vacuum. Can be.
  • any one of the three diffraction gratings can be set at the X-ray incident position by the slit 33 without breaking the vacuum.
  • FIG. 6 is a diagram illustrating a grating tilt adjustment mechanism.
  • the inclination of the diffraction grating set at the X-ray incident position by the slit 33 can be detected by the grating exchange mechanism using the turntable 41 shown in FIG. 5 (a). .
  • the straight line introducer 51 is configured so that the rod in contact with one end of the diffraction grating moves up and down by converting the rotational movement into linear movement, and the height of one side of the diffraction grating at the tip of the aperture Can be adjusted. As a result, it is possible to correct the tilt of the diffraction grating due to an assembly error or the like, and realize an optimal X-ray optical system.
  • FIG. 7 is a view showing another example of the condensing mirror 30.
  • two X-ray focusing mirrors with curved surfaces were used facing each other.
  • a total of four rat focusing mirrors are used in combination.
  • Each mirror is composed of a silicon substrate, and a gold thin film is formed on the facing surface (X-ray incident surface) by sputtering. By forming a thin gold film, the reflection efficiency of X-rays on the mirror surface can be increased.
  • the present invention is not limited to the above-described embodiment, and can be modified.
  • the voltage may be applied to repel secondary electrons.
  • a trapping electrode to which a voltage for attracting secondary electrons is applied may be arranged in the connection tubes 60-1 and 60-2.
  • the X-ray spectrometer is combined with the TEM column.
  • the X-ray spectrometer may be combined with another electron microscope (SEM, EPMA or Auger microprobe). good.
  • an X-ray spectrometer may be attached to the side wall of the sample chamber of SEM, EPMA or Auger microprobe.
  • the term “electron microscope” as used in the present invention is not limited to TEM or SEM, but encompasses all devices having a function of acquiring an image of a sample based on electron beam irradiation on the sample. is there.
  • X-rays from the sample are condensed by a condenser mirror and made incident on the diffraction grating, thereby increasing the intensity of X-rays incident on the diffraction grating, shortening measurement time, The SZN ratio of the spectrum can be improved.
  • the background due to stray light can be reduced, and the SZN ratio of the spectrum can be improved.
  • the electron microscope equipped with the X-ray spectrometer according to the present invention is useful as an apparatus that can obtain a valence band state density distribution.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

L'invention concerne un microscope électronique doté d'un spectromètre à rayons X haute résolution comprenant un système optique compact. Le spectromètre à rayons X (10) comprend une enceinte de spectromètre (11) depuis laquelle de l'air est évacué par des pompes sous vide (18, 19, 20). Un réseau de diffraction à différents intervalles (12) est disposé dans l'enceinte de spectromètre (11) et un détecteur de rayons X (14) est monté à son extrémité. Le spectromètre (11) est monté sur la paroi latérale du microscope électronique par l'intermédiaire d'un clapet obturateur (4). Des rayons X caractéristiques émis par un échantillon (3) auquel un faisceau électronique est appliqué, est incident à un grand angle (α) par rapport à un angle normal du réseau de diffraction à différents intervalles; les rayons X diffractés provenant du réseau de diffraction atteignent le détecteur de rayons X (14) et sont détectés par lui.
PCT/JP2002/001899 2001-10-24 2002-02-28 Microscope electronique dote d'un spectrometre a rayons x WO2003036677A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2001326066A JP2002329473A (ja) 2001-02-27 2001-10-24 Ｘ線分光器を備えた透過型電子顕微鏡
JP2001-326066 2001-10-24

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WO2003036677A1 true WO2003036677A1 (fr) 2003-05-01

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5047682A (fr) * 1973-08-27 1975-04-28
JPH0599863A (ja) * 1991-10-08 1993-04-23 Olympus Optical Co Ltd Ｘ線分光装置
JPH0566599U (ja) * 1992-02-17 1993-09-03 理学電機工業株式会社 Ｘ線分光器
JPH0676780A (ja) * 1992-08-28 1994-03-18 Shimadzu Corp Ｘ線マイクロアナライザ
JPH07209216A (ja) * 1994-01-24 1995-08-11 Rigaku Ind Co 全反射蛍光ｘ線分析装置
JP2000039359A (ja) * 1998-07-23 2000-02-08 Japan Atom Energy Res Inst 円錐回折斜入射分光器及び該分光器用回折格子
JP2000146692A (ja) * 1998-11-10 2000-05-26 Shimadzu Corp 分光器

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5047682A (fr) * 1973-08-27 1975-04-28
JPH0599863A (ja) * 1991-10-08 1993-04-23 Olympus Optical Co Ltd Ｘ線分光装置
JPH0566599U (ja) * 1992-02-17 1993-09-03 理学電機工業株式会社 Ｘ線分光器
JPH0676780A (ja) * 1992-08-28 1994-03-18 Shimadzu Corp Ｘ線マイクロアナライザ
JPH07209216A (ja) * 1994-01-24 1995-08-11 Rigaku Ind Co 全反射蛍光ｘ線分析装置
JP2000039359A (ja) * 1998-07-23 2000-02-08 Japan Atom Energy Res Inst 円錐回折斜入射分光器及び該分光器用回折格子
JP2000146692A (ja) * 1998-11-10 2000-05-26 Shimadzu Corp 分光器

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