WO2022009297A1 - 荷電粒子線装置 - Google Patents
荷電粒子線装置 Download PDFInfo
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- WO2022009297A1 WO2022009297A1 PCT/JP2020/026511 JP2020026511W WO2022009297A1 WO 2022009297 A1 WO2022009297 A1 WO 2022009297A1 JP 2020026511 W JP2020026511 W JP 2020026511W WO 2022009297 A1 WO2022009297 A1 WO 2022009297A1
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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, ion-optical arrangement
- H01J37/147—Arrangements for directing or deflecting the discharge along a desired path
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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
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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, ion-optical arrangement
- H01J37/05—Electron or ion-optical arrangements for separating electrons or ions according to their energy or mass
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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, ion-optical arrangement
- H01J37/10—Lenses
- H01J37/14—Lenses magnetic
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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
- H01J37/24—Circuit arrangements not adapted to a particular application of the tube and not otherwise provided for
- H01J37/241—High voltage power supply or regulation circuits
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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
- H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
- H01J37/28—Electron or ion microscopes; Electron or ion diffraction tubes with scanning beams
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- 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
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- 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
- H01J2237/24475—Scattered electron detectors
Definitions
- the present invention relates to a charged particle beam device that detects charged particles obtained by irradiating a sample with a charged particle beam.
- the charged particle beam device that scans the charged particle beam as a probe on the sample surface to obtain an image of the region includes a scanning electron microscope (SEM: Scanning Electron Microscope), a scanning ion microscope (SIM: Scanning Ion Microscope), and the like. Focused ion beam (FIB: Focused Ion Beam) processing equipment and the like.
- SEM Scanning Electron Microscope
- SIM Scanning Ion Microscope
- FIB Focused Ion Beam
- a sample is irradiated with a charged particle beam as a probe, and electrons generated from the sample are detected while scanning the charged particle beam in a field of view which is an observation region.
- the signal electron is made to collide with the detector to be converted into an electric signal, and this electric signal is measured by an analog digital (A / D) converter at a predetermined time (sampling time). Then, it is converted into a digital signal, and the aggregated result is plotted on the pixels corresponding to the scanning position of the charged particle beam to generate an image corresponding to the scanning region.
- a / D analog digital
- the signal electrons to be detected in the charged particle beam device are roughly classified into secondary electrons (SE: Secondary Electron) and backscattered electrons (BSE: Back Scattered Electron) in which the charged particle beam as a probe is reflected by the sample and emitted. Will be done.
- the image based on the backscattered electron (BSE) may be an image with abundant unevenness information on the sample surface depending on the irradiation energy of the incident electron and the illumination effect depending on the position of the detector, or the composition information inside the sample is abundant. It may be an image. When it is desired to acquire sample composition information, it is necessary to reduce the unevenness information on the sample surface, and various methods for that purpose have been proposed (for example, Patent Document 1).
- both inspection measurement and high resolution of the three-dimensional structure can be achieved in a high-acceleration SEM. It will be possible to do.
- an object of the present invention is to provide a charged particle beam device capable of imparting an energy filter function even to a small BSE detector.
- the charged particle beam apparatus includes a phosphor that converts charged particles generated by irradiation of a sample with the charged particle beam into light, and a detector that detects light from the phosphor.
- a light guide element for guiding the light from the phosphor to the detector, a light amount adjuster for adjusting the amount of light received by the detector via the phosphor and the light guide element, and the above. It is characterized by including a control unit that controls a light amount regulator.
- An example of the user interface screen displayed on the display unit 147 for setting the energy filter is shown.
- Another example of the user interface screen displayed on the display unit 147 for setting the energy filter is shown.
- this scanning electron microscope includes an electron gun 100, an aligner 102, a first condenser lens 103, a second condenser lens 105, a first scanning deflector 106, a second scanning deflector 108, and an objective lens. 113, secondary electron detector 121, mesh electrode 1021, ExB element 1028, phosphor 1023, light guide element 1110, light amount adjuster 1111, photomultiplier tube 112, and non-point corrector 1034. And.
- the scanning electron microscope also includes control units 131, 132, 133, 135, 138, 139, 141, 142, 144, 2021, 2022, 2024, 2025 for controlling the above-mentioned components.
- These control units are controlled by a computer system 146 (control unit).
- the computer system 146 is connected to the recording device 145 and the display device 147.
- the computer system 146 controls each control unit in a unified manner based on the control data and the like stored in the storage device 145.
- the detection signal detected by the two detectors of the secondary electron detector 121 and the phosphor 1023 is stored in the storage device 145, and the measurement result based on the detection signal is displayed on the display device 147 as a user interface described later. obtain.
- the electron gun 100 emits an electron beam (primary electron) 116.
- the electron beam 116 passes through the aligner 102, the astigmatism corrector 1034, the first condenser lens 103, and the second condenser lens 105, and irradiates the sample 114 held by the objective lens 113 on the stage 115 via the sample table 1025. Will be done.
- the aligner 102 is arranged after the electron gun 100 and adjusts the optical axis of the electron beam 116.
- the electron beam 116 is given an acceleration voltage of 10 kV or more as an example.
- the electron gun 100 is controlled by the electron gun control unit 131, the first condenser lens 103 is controlled by the first condenser lens control unit 133, and the second condenser lens 105 is controlled by the second condenser lens control unit 135.
- the aligner 102 is controlled by the aligner control unit 132.
- the astigmatism corrector 1034 operates to correct the astigmatism of the electron beam 116 under the control of the astigmatism corrector control unit 1024.
- a positive voltage is applied to the upper magnetic path 1030 of the objective lens 113 from the booster voltage control unit 141, and a negative voltage is applied to the sample 114 from the sample voltage control unit 144, whereby an electrostatic lens can be formed.
- the objective lens 113 can be used without applying a voltage to the upper magnetic path 1030.
- the upper magnetic path 1030 and the lower magnetic path 1031 of the objective lens 113 have openings on the stage 115 side so that the center of the generated magnetic field strength is as close as possible to the sample 114.
- Such a structure is called a semi-in-lens type.
- the peak of the magnetic field of the objective lens 113 can be made below the lowermost surface of the magnetic path, the focal length of the objective lens 113 is shortened to be less than the distance between the objective lens 113 and the sample 114, and the resolution is high.
- An electron beam can be formed.
- the objective lens control unit 142 controls the exciting current flowing through the coil of the objective lens.
- the objective lens 113 is a semi-in-lens type in the illustrated example, but the objective lens 113 may be an out-lens type objective lens in which the peak of the lens magnetic field is in the magnetic path opening, or a snorkel type objective lens. ..
- an objective lens called a semi-in-lens type objective lens or a snorkel type objective lens as compared with an out-lens type objective lens, it becomes easier to set the focal distance below the distance between the objective lens and the sample. ..
- the primary electron 116 that reaches the sample 114 is scanned two-dimensionally by the first scanning deflector 106 and the second scanning deflector 108, and as a result, a two-dimensional image of the sample 114 is obtained.
- Two-dimensional scanning is generally performed by performing horizontal line scanning while moving the start position in the vertical direction.
- the center position of the two-dimensional image is defined by the first scan deflector 106 controlled by the first scan deflector control unit 137 and the second scan deflector 108 controlled by the second scan deflector control unit 139. ..
- the two-dimensional image is displayed on the display device 147.
- the low-energy secondary electrons 117 emitted from the sample 114 as a result of irradiation of the primary electrons 116 are guided upward by the objective lens 113 and detected by the secondary electron detector 121 located upstream of the objective lens 113.
- the secondary electrons 117 are deflected by the ExB element 1028 arranged upstream of the objective lens 113, pass through the mesh electrode 2022, and reach the secondary electron detector 121.
- the ExB element 1028 is an electron optics element capable of generating an electric field and a magnetic field at right angles, and has a function of separating primary electrons and secondary electrons.
- the ExB element 1028 is controlled by the ExB element control unit 2025, and the secondary electron detector 121 attracts secondary electrons at a high voltage, so that the leakage electric field is blocked by the mesh electrode 1021.
- the secondary electron detector 121 and the mesh electrode 1021 are controlled by the secondary electron detector control unit 2021 and the mesh electrode control unit 2022, respectively.
- the high-energy reflected electrons (backscattered electrons (BSE)) 1017 emitted from the sample 114 are incident on the phosphor 1023, and then pass through the light guide element 1110 and the light amount adjuster 1111 to the photomultiplier tube 1112. It is detected as a reflected electron image by being incident on.
- the phosphor 1023 is arranged at a position between the objective lens 113 and the sample table 1025.
- the backscattered electron detection system 1120 is configured by the phosphor 1023, the light guide element 1110, the light amount adjuster 1111, and the photomultiplier tube 1112.
- a photodiode or silicon photomultiplier can also be used in place of the photomultiplier tube 1112.
- the phosphor 1023 is located below the objective lens 113 and generates photons when the reflected electrons (BSE) 1017 collide with the fluorescent substance.
- the light guide element 1110 is a light guide made of synthetic quartz or the like, and guides the light generated by the phosphor 1023 to the photomultiplier tube 1112.
- the light amount adjuster 1111 has a function of adjusting the amount of light passing through the light guide element 1110.
- the light amount regulator 1111 can be a filter element whose transmittance changes according to the applied voltage. As will be described later, an energy filter can be realized in the BSE detector by adjusting the transmittance TF of the light amount adjuster 1111.
- FIG. 2 is an enlarged view of the phosphor 1023 below the objective lens 113, which is the main part of the scanning electron microscope of the first embodiment.
- the high-energy backscattered electron (BSE) 1017 collides with the phosphor 1023 between the objective lens 113 (upper magnetic path 1030 and lower magnetic path 1031) and the sample table 1025, and emits photons from the phosphor 1023.
- the emitted photon (light) is guided by the light guide element 1110, passes through the light amount regulator 1111, and then reaches the photomultiplier tube 1112.
- the photomultiplier tube 1112 generates an electric signal according to the number of photons that have arrived.
- the electric signal is detected by the BSE detection system control unit 138.
- the phosphor 1023 is formed in a reverse taper shape toward the sample table 1025, and is irradiated with electrons on the tapered surface and the lower surface. Photons are generated when the incident electrons collide with the fluorescent substance inside the phosphor 1023.
- the detection efficiency DQE Detector Quantum Efficiency
- [nu (G D) indicates the dispersion of the signal multiplication factor of the reflected electron detection system 1120, details can be expressed as equation [2].
- m indicates the number of emitted photons per signal electron of the phosphor 1023
- T is a light amount attenuation element (eg, transmittance of the light guide element 1110, quantum efficiency of the photomultiplier tube 1112, etc.).
- ⁇ ( GPM ) indicates the variance of the signal amplification factor of the photomultiplier tube 1112.
- the variance ⁇ ( GPM ) is expressed as [Equation 3].
- ⁇ of [Equation 3] indicates the amplification factor per stage of the photomultiplier tube 1112.
- the energy possessed by one backscattered electron is hereinafter referred to as BSE energy E BSE.
- BSE energy E BSE the energy possessed by one backscattered electron.
- T TL ⁇ TF as the product of the transmittance TL of the light guide element 1110 and the transmittance TF of the light amount regulator 1111. Therefore, [Equation 4] can be rewritten as [Equation 5] below.
- FIG. 3 shows the result of simulating the effect of the energy filter when the transmittance TF of the light amount regulator 1111 is changed by using the [Equation 5] obtained from the above.
- the upper graph of FIG. 3 is a graph showing the relationship between the BSE energy E BSE and the detection efficiency DQE for each different transmittance TF.
- the lower graph of FIG. 3 is a graph showing the relationship between the reciprocal 1 / TF of the transmittance TF and the energy threshold value (keV).
- m' 20 (/ kV)
- TL 0.025
- the transmittance TF is converted into a value that is intuitively easy for the user to understand, for example, an energy threshold value.
- the lower graph of FIG. 3 is a graph in which the horizontal axis is the reciprocal of TF 1 / TF and the vertical axis is the energy threshold value.
- the energy threshold can be defined as the value of the energy of the reflected electrons when the detection efficiency of the photomultiplier tube 1112 becomes equal to or less than a predetermined value in relation to the reference value.
- the graph on the lower side of FIG. 3 can be accurately approximated by a quadratic equation.
- the relationship between the transmittance TF and the energy threshold value can be discretely stored in the computer system 146 in the form of a table. It is possible to set the transmittance TF from the energy threshold value input from the user interface described later and set the energy filter.
- FIG. 4 shows an example of a user interface screen displayed on the display unit 147 for setting the energy filter.
- the energy discrimination condition setting window 1301 for setting the energy filter is displayed on the display device 147.
- the window 1301 includes an energy threshold setting box 1302 for allowing the user to set the above-mentioned energy threshold. By dragging the bar in the box 1302 using, for example, a mouse, the energy threshold value can be changed to an arbitrary value, whereby the transmittance TF of the light amount regulator 1111 can be changed.
- the window 1301 also includes a preset selection unit 1303 for absorbing differences in energy thresholds between different devices.
- a preset selection unit 1303 for example, by selecting "conventional device 1" or the like, it is possible to select the light amount adjustment equivalent to that of the conventional device.
- the light guide element 1110 and the photomultiplier tube 1112 shown in FIG. 1 may have different transmittance TFs and quantum efficiencies between different devices.
- the energy threshold value may change, and an unintended change in image quality may occur.
- the energy threshold value equivalent to that of the "conventional device 1" can be selected in the device.
- the same detection efficiency DQE can be obtained for the same BSE energy E BSE in relation to the conventional device.
- the transmittance and quantum efficiency may vary among the multiple devices. Due to the above variation, the energy threshold value changes between a plurality of devices, and an unintended change in image quality occurs between the plurality of devices. According to the preset selection unit 1303, it is possible to suppress a change in image quality when a plurality of charged particle beam devices of the same model are manufactured.
- FIG. 5 shows another example of the user interface.
- the screen of this user interface includes an image quality adjustment box 1304 instead of the energy threshold setting box 1302.
- the image quality adjustment box 1304 is a box for setting any one of a plurality of options for the level of the image quality of the captured image to be captured, such as image quality 1, image quality 2, and so on.
- the energy threshold value is selected from the user interface, or the preset condition is input from the preset selection unit 1303 (step S10).
- the transmittance TF that can realize the energy threshold value is determined based on the formula or table stored in the computer system 146 (step S12). Then, the determined transmittance TF is set in the light amount regulator 1111 (step S14).
- the value of the transmittance TF of the light amount regulator 1111 can be changed, and the energy filter of BSE can be realized.
- the light amount adjuster 1111 of the present embodiment can use a movable iris diaphragm generally used in an optical microscope or the like as a light receiving area adjusting means.
- the iris diaphragm is an element that adjusts the amount of light by blocking the light on the outer circumference from the hole by changing the size of the hole through which light passes in an axisymmetric manner with respect to the center of the optical axis. Therefore, only the light at the center of the optical axis passes through, and the light at the outer periphery is blocked.
- the reflected electron 1017 collides with the center of the phosphor 1023, it can pass through the iris diaphragm, but if it collides with the outer periphery, the iris diaphragm is used. It may not be possible to pass through and the light may be blocked. As a result, whether or not the signal can be detected is determined by the emission angle of the reflected electrons 1017 from the sample 114, which may lead to an unintended change in image quality. For example, in FIG.
- the above concerns can be further reduced by taking the measures described below for the energy possessed by the primary electron 116. This will be specifically described with reference to FIG.
- FIG. 7 shows the result of a Monte Carlo simulation of the behavior of the scattered electrons 1016 in the sample 114 when the primary electrons 116 are incident on the sample 114. It is assumed that the acceleration voltage of the primary electron 116 is 5 kV and the sample 114 is silicon (Si).
- the figure on the left side of FIG. 7 shows the result of incidenting 100 primary electrons 116 on the sample 114, and the figure on the right side shows the result of incidenting 10,000 primary electrons 116.
- the primary electrons 116 are randomly scattered when they are incident on the sample 114, and the primary electrons accidentally emitted from the surface are observed as reflected electrons 1017.
- a lightning-like locus can be seen in the scattering in the sample 114 as shown in the figure on the left.
- the locus where the scattering 1016 is generated can be approximated by a sphere cut by the sample 114. This sphere is called a scattering sphere.
- the depth from the surface of the sample 114 to the lower part of the scattering sphere is R
- the radius of the cross section of the scattering sphere on the surface of the sample 114 is rB.
- RS be the period of the periodic structure in the plane direction of the sample 114 observed by the charged particle beam device.
- the radius rB is sufficiently larger than the period Rs, the unevenness information on the surface of the sample 114 possessed by the backscattered electrons 1017 and the secondary electrons 117 emitted from the sample 114 is averaged by the scattering of the primary electrons 116 in the sample. It is possible to reduce the above-mentioned concerns. Empirically, if the radius rB is more than twice the period Rs ([Equation 6] below), the above concerns can be fully ignored.
- the radius r B can be calculated by substituting ⁇ of [Equation 8] and R of [Equation 11] into [Equation 10].
- the radius R depends on E 0 for the energy of the atomic number Z, the atomic weight A, the density ⁇ (g / cm 3 ), and the primary electron beam 116, and in particular E it is important to be monotonically increasing in E 0> 0 for 0. That is, if the acceleration voltage of the primary electron 116 is sufficiently high, the radius rB of the cross section of the scattering sphere becomes large, and if this radius rB is more than twice larger than the period Rs, the unevenness of the sample due to the illumination effect of the backscattered electrons.
- the information can be small enough. That is, it was found that it is effective to set the condition of [Equation 6].
- the unevenness information can be sufficiently reduced by setting the acceleration voltage to 5 kV or more.
- the fine structure of a semiconductor composed of silicon (Si) is used as the sample 114.
- the atomic number Z 14
- the atomic weight A 28.1
- the density ⁇ 2.33 (g / cm 3 ) of silicon
- the size R of the microstructure sample in the plane direction is 133 nm.
- the size of one cycle of a line microstructure sample of a 14 nm process rule semiconductor, which has been started in recent years, is about 40 to 50 nm, and rB is sufficiently larger than this.
- the irradiation energy of the charged particle beam to be irradiated is 5 keV or more even in a fine structure sample of about 100 nm mainly composed of other general semiconductors.
- FIGS. 8 and 9 The overall configuration of the scanning electron microscope of the second embodiment is the same as that of the first embodiment (FIG. 1) except for the parts described with reference to FIGS. 8 and 9.
- FIGS. 8 and 9 the same reference numerals as those in FIGS. 1 to 7 indicate the same parts, so duplicate description will be omitted.
- the multi-anode photomultiplier tube 1114 is adopted as the photodetection means.
- the output of the multi-anode photomultiplier tube 1114 is output to the signal processing circuit 1115 via an amplifier and output to the computer system 146.
- the energy filter is realized in the BSE detector by changing the transmittance TF of the light amount regulator 1111.
- the multi-anode photomultiplier tube is realized.
- the amount of received light is adjusted by adjusting the light receiving area in the photomultiplier tube by selecting at least one of the plurality of light receiving surfaces, and an energy filter is realized.
- FIG. 8 is a partial schematic view of the reflected electron detection system 1120 of the scanning electron microscope.
- the multi-anode photomultiplier tube 1114 has a plurality of divided light receiving surfaces, and at least one of a plurality of light receiving signals from the plurality of light receiving surfaces is added by a signal processing circuit 1115 in the subsequent stage to obtain an image. It is a signal.
- the signal processing circuit 1115 has a switching function / addition function for selecting which of the signals output from the plurality of light receiving surfaces is to be added.
- the light receiving surface of the multi-anode photomultiplier tube 1114 can be divided into five light receiving surfaces.
- the transmittance TF is set to 0.2 (20) of 1/5 in the first embodiment. The same effect as that of%) can be obtained.
- the relationship between the number of light receiving surfaces to be used and the energy threshold value can be acquired in advance, and the same user interface as that of the first embodiment can be adopted.
- the number of divisions of the light receiving surface of the multi-anode photomultiplier tube 1114 is not limited to the above.
- the output signal output by each of the plurality of light receiving surfaces may be stored in the computer system 146 under predetermined conditions.
- This also supports, for example, the case where the contact area between the light guide element 1110 and the multi-anode photomultiplier tube 1114 is not constant, or the case where the light-receiving sensitivity of the multi-anode photomultiplier tube 1114 varies among a plurality of light-receiving surfaces. It is expected that the accuracy of setting the energy threshold will be improved.
- the signal processing circuit 1115 instead of selecting at least one of the plurality of light receiving surfaces in the signal processing circuit 1115, the signal processing circuit 1115 obtains based on the light receiving signals of all the light receiving surfaces.
- the generated electric signal can be temporarily stored in the recording device 145. After that, when an arbitrary energy threshold value is set in the user interface, the stored electric signal is added according to the threshold value to obtain an image signal of the sample. This method is advantageous over the above-described embodiment in that the energy threshold value can be set after the image of the sample is taken.
- the scattering element 1119 can be formed on the side surface of the light guide element 1110 as a light guide. This makes it possible to prevent the image of the light emitting position of the phosphor 1023 from being formed on the light receiving surface of the multi-anode photomultiplier tube 1114.
- the scattering element 1119 can be a scattering element such as an aluminum sleeve whose surface is sufficiently coarser than the emission wavelength of the phosphor 1023.
- the scattering element 1119 reduces the illumination effect (reduces the anisotropy of the reflected electron signal), and at the same time, the image of the light emitting position of the phosphor 1023 is the light receiving surface of the multi-anode photomultiplier tube 1114. It is possible to prevent the image from being formed on the surface.
- FIG. 9 shows a further suitable modification of the second embodiment.
- a light guide element 1110 having a smaller cross-sectional diameter is connected to the multi-anode photomultiplier tube 1114.
- the non-detection light receiving surface 1141 and the detected light receiving surface are symmetrical with respect to the central axis of the light guide element 1110.
- Surface 1140 is selected by computer system 146. By doing so, the illumination effect on the reflected electrons can be reduced, and the anisotropy of the reflected electron signal can be reduced.
- the received light amount is adjusted as in the first embodiment, it is possible to impart the function of the energy filter to the small BSE detector. It becomes. Further, in the second embodiment, the signal from all the dividing surfaces of the multi-anode photomultiplier tube 1114 can be once acquired and stored, and then any signal can be added. It is more advantageous than the embodiment.
- FIG. 10 is a side view of the structure of the backscattered electron detection system 1120
- FIG. 11 is a perspective view.
- this third embodiment also employs a method of adjusting the amount of received light in the backscattered electron detection system 1120 by changing the light receiving area in the photomultiplier tube.
- the multi-anode photomultiplier tube 1114 is used, whereas in the third embodiment, a plurality (for example, one of the phosphor 1023 and one light guide element 1110) are used. It is equipped with 4) photomultiplier tubes 1116.
- four detectors are arranged at approximately equal intervals in the circumferential direction so as to be axisymmetric with respect to the primary electron 116, but the number of detectors and the arrangement interval are limited to a specific format. It is not something that is done.
- the phosphor 1023 and the light guide element 1110 can have a concentric circular shape (doughnut shape) as shown in FIG.
- the computer system 146 when some of the plurality of photomultiplier tubes 1116 are selected, the computer system 146 is oriented so that the selected photomultiplier tubes 1116 are axially symmetric with respect to the electron beam 116. Can be configured. Thereby, the anisotropy of the signal can be reduced as in the second embodiment.
- At least one of the plurality of photomultiplier tubes 1116 may be selected in the signal processing circuit unit 1115, or the photomultiplier tubes 1116 can be obtained from all the photomultiplier tubes 1116.
- the electric signal may be temporarily stored in the storage device 145, and then the electric signal to be added may be selected (similar to the second embodiment). Therefore, according to the third embodiment, the same effect as that of the second embodiment can be obtained.
- the plurality of reflected electron detection systems composed of any one of the plurality of photomultiplier tubes 1116 and the corresponding phosphor 1023 and the light guide element 1110 may have different characteristics and structures from each other.
- the energy threshold value and the transmittance TF may be different from each other among a plurality of backscattered electron detection systems.
- the effect of emphasizing the lighting effect can be expected by changing the energy threshold value among the plurality of backscattered electron detection systems.
- the first embodiment is in that signals from all of the plurality of photomultiplier tubes 1116 can be once acquired and stored, and then any signal can be added. It is more advantageous than.
- the overall configuration of the scanning electron microscope of the fourth embodiment is the same as that of the first embodiment (FIG. 1) except for the point described with reference to FIG. In FIG. 12, the same reference numerals as those in FIG. 1 indicate the same parts, so duplicate description will be omitted.
- the stage 115 is configured to be movable in the direction of the primary electrons 116, and the distance between the objective lens 113 and the sample 114 can be adjusted.
- the objective lens 113 can focus on the sample 114 at a long focal length, so that it can also focus on the primary electron 116 having a high acceleration voltage.
- the stage 115 can be kept close to the objective lens 113 up to an acceleration voltage of 30 kV, the stage 115 can be lowered at an acceleration voltage of 45 kV, and the objective lens 113 sample 114 can be focused at a distance.
- the acceleration voltage of the electron beam 116 is 60 kV
- the median energy of the secondary electrons 117 at the time of emission from the sample 114 is -1 to -2 eV.
- the energy of the secondary electrons at the time of collision with the phosphor 1023 becomes a value substantially equal to the sample table voltage.
- the energy of the backscattered electrons 1017 at the time of emission from the sample 114 depends on the material of the sample 114, but the median value is generally 1/2 to 2/3 of the energy of the primary electrons 116. Therefore, the backscattered electrons 1017 have higher energy than the secondary electrons 117. For example, when the acceleration voltage of the electron beam 116 is 60 kV, the median energy of the reflected electrons 1017 at the time of emission from the sample 114 is often 30 KeV to 40 KeV.
- the energy threshold value for the transmittance TF of the light amount regulator 1111 By setting the energy threshold value for the transmittance TF of the light amount regulator 1111 to the energy of about the sample table voltage, the secondary electrons 117 cannot be detected.
- the transmittance TF By setting the transmittance TF in this way, it is possible to cut the signal of the secondary electrons 117, and it is possible to emphasize only the signal of the backscattered electrons 1017.
- the present invention is not limited to the above-described embodiment, and includes various modifications.
- the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations.
- the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations.
- it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. ..
- Sample stand voltage control unit 145 ... Recording device, 146 ... Computer System, 147 ... Display device, 1017 ... Reflected electron (BSE), 1021 ... Mesh electrode, 1023 ... Phosphorant, 1025 ... Sample table, 1028 ... ExB element, 1030 ... Upper magnetic path, 1031 ... Lower magnetic path, 1034 ... Non Point corrector, 1110 ... Light guide element, 1111 ... Light amount adjuster, 1112 ... Photoelectron multiplying tube, 1114 ... Multi-anodic photoelectron multiplying tube, 1115 ... Signal processing circuit unit, 1119 ... Scattering element, 1301 ... Energy discrimination condition setting Window, 1302 ... Energy threshold setting box, 1303 ... Preset selection unit, 1304 ... Image quality setting box.
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Abstract
Description
しかし、上記のような小型のBSE検出器においてエネルギーフィルタの機能を付与することは困難であった。
図1~図6を参照して、第1の実施の形態に係る荷電粒子線装置を説明する。ここでは荷電粒子線装置の一形態として走査電子顕微鏡(SEM)を例にとって説明するが、以下の実施の形態は、走査電子顕微鏡以外の荷電粒子線装置にも適用可能である。
次に、図8を参照して、第2の実施の形態に係る荷電粒子線装置を説明する。ここでも、荷電粒子線装置の一形態として走査電子顕微鏡(SEM)を例にとって説明するが、以下の実施の形態は、走査電子顕微鏡以外の荷電粒子線装置にも適用可能である。
次に、第3の実施の形態に係る荷電粒子線装置を、図10及び図11を用いて説明する。
ここでも、荷電粒子線装置の一形態として走査電子顕微鏡(SEM)を例にとって説明するが、以下の実施の形態は、走査電子顕微鏡以外の荷電粒子線装置にも適用可能である。
次に、第4の実施の形態に係る荷電粒子線装置を、図12参照して説明する。ここでも、荷電粒子線装置の一形態として走査電子顕微鏡(SEM)を例にとって説明するが、以下の実施の形態は、走査電子顕微鏡以外の荷電粒子線装置にも適用可能である。
Claims (13)
- 荷電粒子線の試料への照射によって生じた荷電粒子を光に変換する蛍光体と、
前記蛍光体からの光を検出する検出器と、
前記光を前記蛍光体から前記検出器に導くための導光素子と、
前記検出器が前記蛍光体及び前記導光素子を介して受光する光の光量を調整する光量調整器と
前記光量調整器を制御する制御部と
を備えることを特徴とする荷電粒子線装置。 - 前記光量調整器は、制御信号に従い光の透過率を変更可能な素子であり、
前記制御部は、前記光量調整器の透過率を制御する
請求項1に記載の荷電粒子線装置。 - 前記蛍光体は、光の発光量が前記荷電粒子線のエネルギーの増加に応じて単調に増加又は単調に減少する特性を有する、請求項1に記載の荷電粒子線装置。
- 前記蛍光体は、対物レンズと前記試料を載置する試料台との間の位置に配置される、請求項1に記載の荷電粒子線装置。
- 前記検出器は、複数の受光面を有し、
前記制御部は、前記複数の受光面のうち加算対象とされる受光面を選択するよう構成される、請求項1に記載の荷電粒子線装置。 - 前記検出器は、分割された複数の受光面を有するマルチアノード光電子増倍管であり、
前記制御部は、前記マルチアノード光電子増倍管の複数の受光面のうち加算対象とされる受光面を選択するよう構成される、請求項5に記載の荷電粒子線装置。 - 前記制御部は、複数の受光面の各々からの信号に基づく複数通りの演算結果を記憶部に記憶させると共に、
前記複数通りの演算結果から選択された演算結果を加算する、請求項5に記載の荷電粒子線装置。 - 前記光量調整器を調整するためのパラメータの入力を可能とされたユーザインタフェースを表示する表示部を更に備える、請求項1に記載の荷電粒子線装置。
- 前記ユーザインタフェースから指定される前記パラメータは、前記光量調整器の検出効率が、基準値との関係で所定値以下となるときの反射電子のエネルギーとしてのエネルギー閾値である、請求項8に記載の荷電粒子線装置。
- 前記ユーザインタフェースは、撮影画像の画質のレベルを入力可能に構成された、請求項8に記載の荷電粒子線装置。
- 前記ユーザインタフェースは、他の装置のパラメータを選択可能に構成された、請求項8に記載の荷電粒子線装置。
- 前記導光素子は、その側面の一部に光を散乱させる散乱素子を有する、請求項1に記載の荷電粒子線装置。
- 前記試料の平面方向の周期的構造の周期をRs、照射される前記荷電粒子線の照射エネルギーで決定される前記荷電粒子線の前記試料内での散乱球径をrBとした場合、
Rs<2×rBを満たす、請求項1に記載の荷電粒子線装置。
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JPH11352230A (ja) * | 1998-06-04 | 1999-12-24 | Hamamatsu Photonics Kk | X線画像検出装置 |
JP2005071746A (ja) * | 2003-08-22 | 2005-03-17 | Canon Inc | 電子顕微鏡用撮像装置 |
JP2020017415A (ja) * | 2018-07-26 | 2020-01-30 | 株式会社日立ハイテクノロジーズ | 荷電粒子線装置 |
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US20070090288A1 (en) * | 2005-10-20 | 2007-04-26 | Dror Shemesh | Method and system for enhancing resolution of a scanning electron microscope |
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JP6267529B2 (ja) | 2014-02-04 | 2018-01-24 | 株式会社日立ハイテクノロジーズ | 荷電粒子線装置及び画像生成方法 |
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JPH11352230A (ja) * | 1998-06-04 | 1999-12-24 | Hamamatsu Photonics Kk | X線画像検出装置 |
JP2005071746A (ja) * | 2003-08-22 | 2005-03-17 | Canon Inc | 電子顕微鏡用撮像装置 |
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