WO2022091180A1 - 荷電粒子線装置 - Google Patents

荷電粒子線装置 Download PDF

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Publication number
WO2022091180A1
WO2022091180A1 PCT/JP2020/040104 JP2020040104W WO2022091180A1 WO 2022091180 A1 WO2022091180 A1 WO 2022091180A1 JP 2020040104 W JP2020040104 W JP 2020040104W WO 2022091180 A1 WO2022091180 A1 WO 2022091180A1
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Prior art keywords
sample
charged particle
electron beam
pulsed
light
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Ceased
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PCT/JP2020/040104
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English (en)
French (fr)
Japanese (ja)
Inventor
洋平 中村
夏規 津野
保宏 白崎
美南 庄子
将太 三次
裕子 笹氣
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Hitachi High Tech Corp
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Hitachi High Tech Corp
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Priority to US18/031,359 priority Critical patent/US12573586B2/en
Priority to JP2022558613A priority patent/JP7377375B2/ja
Priority to PCT/JP2020/040104 priority patent/WO2022091180A1/ja
Priority to KR1020237012463A priority patent/KR102794066B1/ko
Priority to TW110139005A priority patent/TWI795043B/zh
Publication of WO2022091180A1 publication Critical patent/WO2022091180A1/ja
Anticipated expiration legal-status Critical
Ceased 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
    • H01J37/22—Optical, image processing or photographic arrangements associated with the tube
    • 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
    • H01J37/261—Details
    • H01J37/265—Controlling the tube; circuit arrangements adapted to a particular application not otherwise provided, e.g. bright-field-dark-field illumination
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
    • G01R31/302—Contactless testing
    • G01R31/308—Contactless testing using non-ionising electromagnetic radiation, e.g. optical radiation
    • G01R31/311—Contactless testing using non-ionising electromagnetic radiation, e.g. optical radiation of integrated circuits
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
    • G01N23/225—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion
    • G01N23/2251—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion using incident electron beams, e.g. scanning electron microscopy [SEM]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0046—Arrangements for measuring currents or voltages or for indicating presence or sign thereof characterised by a specific application or detail not covered by any other subgroup of G01R19/00
    • G01R19/0061—Measuring currents of particle-beams, currents from electron multipliers, photocurrents, ion currents; Measuring in plasmas
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • 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
    • H01J37/22—Optical, image processing or photographic arrangements associated with the tube
    • H01J37/226—Optical arrangements for illuminating the object; optical arrangements for collecting light from the object
    • 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
    • H01J37/26—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
    • H01J2237/2448—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
    • H01J2237/245—Detection characterised by the variable being measured
    • H01J2237/24564—Measurements of electric or magnetic variables, e.g. voltage, current, frequency

Definitions

  • the present invention relates to a charged particle beam device.
  • One of the sample analysis methods using an electron microscope is to form a potential contrast image based on the detection of secondary electrons and the like obtained by irradiating the sample with an electron beam, and based on the analysis of the potential contrast image, the sample.
  • a method for evaluating the electrical characteristics of the element formed above is known.
  • Patent Document 1 discloses a method of calculating an electric resistance value from a potential contrast and discriminating a defect. Further, in Patent Document 2, a method of accurately predicting the characteristics of defects such as electric resistance value by creating a netlist as an equivalent circuit that describes information including electrical characteristics and connection information of circuit elements from potential contrast. Is disclosed.
  • Patent Document 3 describes that the time change of the charge amount can be captured by pulsed the electron beam and controlling the timing of sampling the secondary electrons emitted from the sample in synchronization with the pulsed timing of the electron beam. Is disclosed.
  • Patent Document 4 by irradiating a sample with ultraviolet light, the surface of the insulating film is made conductive, and even when an abnormal charge is formed on the surface of the insulating film, the abnormal charge is alleviated and the surface potential is reduced. It is disclosed that it can be stabilized.
  • Japanese Unexamined Patent Publication No. 2003-100823 Japanese Unexamined Patent Publication No. 2008-130582 Japanese Unexamined Patent Publication No. 2012-252913 Japanese Patent Application Laid-Open No. 2003-151483
  • Patent Documents 1 and 2 disclose a method of estimating the resistance value of a sample using potential contrast.
  • the observation method disclosed in Patent Document 3 is effective.
  • the time required for the charge amount to change becomes long, so that the imaging necessary for acquiring an image with sufficient contrast is required. Time increases.
  • one of the objects of the present invention is to provide a charged particle beam device capable of estimating the electrical characteristics of a sample including the capacitance characteristics at high speed.
  • a charged particle optical system that irradiates a sample with a pulsed charged particle beam, an optical system that irradiates a sample with light, and a pulsed charged particle beam irradiate the sample.
  • the detector that detects the secondarily charged particles emitted by this method and the charged particle optical system that irradiates the sample with pulsed charged particle beams under predetermined electron beam pulse conditions are controlled, and light is applied under predetermined light irradiation conditions. It has a control unit that controls the optical system so as to irradiate the sample with light, and a calculation device that sets a predetermined electron beam pulse condition and a predetermined light irradiation condition.
  • the amount of the secondary charged particle signal detected by the detector by irradiating with the pulsed particle beam under the first electron beam pulse condition and the second electron beam pulse condition different from the first electron beam pulse condition Based on the difference from the amount of the secondary charged particle signal detected by the detector by irradiating the pulsed particle beam with, one of a plurality of light irradiation conditions is set to a predetermined light irradiation condition.
  • a charged particle optical system that irradiates a sample with a pulsed charged particle beam, an optical system that irradiates a sample with light, and a pulsed charged particle beam are samples.
  • the calculation device irradiates the sample with light.
  • the amount of the first secondary charged particle signal detected by the detector by irradiating the pulsed charged particle beam under the first electron beam pulse condition and the non-pulse charged particle beam than the first electron beam pulse condition.
  • the intermediate value with the second secondary charged particle signal amount detected by the detector is obtained, and light is applied to the sample.
  • a predetermined light irradiation condition is set so that the amount of the secondary charged particle signal detected by the detector by irradiating and irradiating the pulsed charged particle beam under an arbitrary electron beam pulse condition becomes a value equivalent to an intermediate value.
  • Arbitrary electron beam pulse conditions when predetermined light irradiation conditions are set are set to predetermined electron beam pulse conditions.
  • FIG. 1 shows an example of a configuration of a charged particle beam device.
  • the electron microscope main body 100 irradiates a sample with light in addition to elements constituting a general electron microscope such as an electron optical system, a stage mechanism system, a control system, a signal analysis system, and an image processing system. It has a light irradiation system for.
  • the electron optics system includes an electron gun 101, a blanker 102, an aperture 103, a deflector 104, and an objective lens 105, which are sources of charged particles.
  • the electrons emitted from the electron gun 101 are pulsed by the blanker 102 and the aperture 103, and are focused on the sample 106 by the objective lens 105.
  • the pulsed electron beam is two-dimensionally scanned on the sample 106 by the deflector 104.
  • the stage mechanism system has a stage 107 movable on the XYZ axis and a sample table 108 on the stage 107, and the sample 106 is installed on the sample table 108. Further, although not shown, a retarding power supply for applying a voltage to the sample 106 may be connected.
  • the light irradiation system includes a light source 109, an optical path breaker 110, and an optical path 111.
  • the continuous light or pulsed light emitted from the light source 109 is gated by the optical path breaker 110 to control the irradiation of the sample 106.
  • the light from the light source 109 is focused on the sample 106 by the optical path 111.
  • the optical path 111 may be configured to include a general optical element such as a mirror, a lens, or a splitter, an optical fiber, or the like.
  • the control device 112 is connected to an electron optical system to control the acceleration voltage and irradiation current of the electron beam and the deflection position, and is connected to the light irradiation system to control the wavelength and intensity of light and control the focusing position. I do. Further, the control device 112 is connected to the blanker 102, the optical path breaker 110, and the detector 113, and controls to synchronize the electron beam pulse timing, the light ON / OFF timing, and the secondary electron sampling timing. ,It is configured.
  • the calculation device 114 generates an image, classifies defects, measures electrical characteristics, etc. based on the secondary electronic signals acquired by the detector 113 and the control device 112, and outputs the images to the input / output device 115.
  • the input / output device 115 is mounted by a display, a keyboard, a mouse, a control panel-shaped switch, or the like, but may be a remote PC or the like via a network.
  • the charged particle beam apparatus may include a wafer transfer system.
  • a wafer cassette 116 on which the wafer is installed a wafer loader 117 for introducing the wafer into the electron microscope, a preparation chamber 118 for installing the wafer before introducing the wafer into the sample chamber 119, and the like are provided.
  • FIGS. 2A to 2B The transient response of sample charging by irradiation with electron beam and light will be described with reference to FIGS. 2A to 2B.
  • an electron microscope applies a constant acceleration voltage to a sample and irradiates it with an electron beam, secondary electrons are emitted from the sample.
  • the emitted secondary electrons are detected by the detector and synchronized with the scanning of the electron beam to form a secondary electron image.
  • the amount of secondary electrons emitted from the sample changes depending on the current of the electron beam incident on the sample, the acceleration voltage, the material of the sample surface, the uneven structure, the charge on the surface, and the like.
  • a positively charged state in which the amount of secondary electrons emitted from the sample is larger than the number of incident electrons or a negatively charged state in which the amount of secondary electrons emitted from the sample is smaller than the number of incident electrons occurs. ..
  • a state in which a positive charge is generated by irradiation with an electron beam will be described, but the same applies even in a state in which a negative charge is generated, only the change in the surface potential of the sample is different.
  • FIG. 2A is a cross-sectional view of an example of the sample 106.
  • the insulating film 202 is formed on the wafer substrate 201, and the floating conductor 203 is formed on the insulating film 202.
  • the insulating film 202 is, for example, SiO 2 or Si 3 N 4 or the like.
  • the equivalent resistance R and the equivalent capacitance C as shown in the figure exist between the floating conductor 203 and the wafer substrate 201.
  • FIG. 2B shows the change in the surface potential of the floating conductor 203 when the sample of FIG. 2A is irradiated with a pulsed electron beam.
  • the incident electron beam causes positive charging
  • the surface potential of the sample increases during the irradiation period of the pulsed electron beam, while the non-irradiation period of the pulsed electron beam is determined from the product of the above-mentioned equivalent resistance R and equivalent capacitance C.
  • the surface potential of the sample decreases as the current flows through the wafer substrate according to the time constant. Further, when the surface potential of the sample increases, the electric potential directly above the sample changes and a potential barrier is generated, so that among the secondary electrons once emitted from the sample, the secondary electrons having low energy are returned to the sample again.
  • the contrast generated in an image due to such a change in surface potential is called potential contrast. It is possible to indirectly capture the change in the charge of the sample by the potential contrast.
  • FIG. 2B shows the amount of secondary electron signals detected when the sample is irradiated with a pulsed electron beam when the time constant of the surface potential change is short and when the time constant of the surface potential change is long. There is. In this way, if the same amount of secondary electron signals is to be obtained for both, the pulse non-irradiation time (interval time) T 2 when the time constant of the surface potential change is long is the case where the time constant of the surface potential change is short. It must be longer than the pulse non - irradiation time T1 of.
  • the insulating film is made conductive by irradiating the irradiation point of the pulsed electron beam with light having a wavelength shorter than the absorption edge of the insulating film (light having energy exceeding the band gap of the insulating film).
  • the equivalent resistance R shown in FIG. 2A is lowered, and as a result, the time constant determined by the product of the equivalent resistance R and the equivalent capacitance C is shortened.
  • the sample with light having a predetermined wavelength and irradiating the sample with a pulsed electron beam it is possible to obtain a large amount of secondary electron signals even in a short interval time.
  • FIG. 3 is a plot in which the equivalent capacitance C is fixed and the equivalent resistance R is used as a parameter for how the amount of secondary electron signals changes depending on the interval time.
  • the equivalent resistance R is 100 G ⁇
  • the resistance values are 10 G ⁇ and 1 G ⁇
  • the secondary is secondary according to the pulse interval time. Changes in the amount of electronic signals can be seen over a wide range.
  • the resistance value becomes low to 0.1 G ⁇
  • the change according to the interval time cannot be seen again. This is because the time constant of the potential change becomes too short and the charge immediately converges to the steady state.
  • FIGS. 4A to 4B show a flow in which the irradiation conditions of the light / electron beam in Example 1 are set and the inspection is executed.
  • the arithmetic unit 114 executes this flow.
  • the sample is loaded, and after setting electron beam optical conditions such as acceleration voltage and irradiation current, the sample moves to the position of the sample coordinates for setting the conditions (S401).
  • the condition setting coordinates may be arbitrarily determined as long as the structure of the sample at the coordinates has the same structure as the structure at the inspection target coordinates.
  • the electron beam pulse condition is set to a certain condition (electron beam pulse condition A).
  • the electron beam pulse condition A is set to the interval time Ta [seconds].
  • the light irradiation condition is set to one of the specified ranges.
  • the irradiation condition of light is the irradiation light intensity
  • the irradiation light intensity is specified in n ways of P1, P2, ... Pk, ... Pn [W] (n is a natural number, k is any one of 1 to n). Is possible.
  • the irradiation light intensity is set to Pk [W] (S403), the sample is irradiated with light and an electron beam, and the secondary electron signal S (Ta, Pk) is acquired (S404).
  • the amount of secondary electron signals may be an average value obtained by scanning the structure to be inspected, or may be a value obtained from a certain point.
  • Steps S403 and S404 are executed for all the light irradiation conditions P1 to Pn, and after completion (S405), different electron beam pulse conditions B are set.
  • the electron beam pulse condition B is set to the interval time Tb [seconds] (S406).
  • the secondary electron signals S (Tb, Pk) are acquired for all the light irradiation conditions P1 to Pn (S407 to S409).
  • the electron beam pulse condition is set to one of the specified ranges.
  • the electron beam pulse condition is set as the interval time, and the interval time can be specified in m ways of T1, T2, ... Tl, ...
  • Tm [second] (m is a natural number, l is any of 1 to m). do.
  • the interval time is set to Tl [seconds] (S411)
  • the sample is irradiated with light and an electron beam
  • the secondary electron signal S (Tl, Pmax) is acquired (S412).
  • Steps S411 and S412 are executed for all interval times T1 to Tm (S413).
  • the difference ⁇ S (Tl 1 , Pmax) -S (Tl 2 , Pmax) ⁇ is calculated for the interval times Tl 1 and Tl 2 at two different points, and the difference is equal to or greater than a predetermined threshold value.
  • Interval times Tl 1 and Tl 2 are obtained so that the total (Tl 1 + Tl 2 ) is minimized, and these are set as electron beam pulse conditions X and Y (S414).
  • the electron beam pulse conditions X and Y are set to interval times Tx and Ty [seconds], respectively.
  • the stage is moved to the inspection target coordinates (S415), and the secondary electron signals S (Tx, Pmax) and S (Ty, Pmax) for each inspection coordinate are set under the light irradiation condition ⁇ and the electron beam pulse conditions X and Y. Acquire (S416).
  • the charged particle beam device holds a database on the relationship between the secondary electron signal S acquired by simulation or a similar sample in advance and the resistance value / capacitance value of the sample.
  • the database holds information on the dependence of the amount of secondary electron signals on the interval time with the equivalent resistance R as a parameter, as shown in FIG. 3, for each equivalent capacity C. ing.
  • a database holding information about the dependence of the secondary electron signal amount on the condition is maintained.
  • the resistance value / capacitance value such that S (Tx, Pmax) and S (Ty, Pmax) are estimated, and the temporary resistance value and capacitance value to be inspected are used (S417).
  • temporary resistance value means that the resistance value estimated here is the resistance value under the influence of the light irradiation under the light irradiation condition ⁇ (the resistance value lower than the state without the light irradiation). This is because it is). It is not necessary to consider the effect of light on the capacitance value.
  • the irradiation light intensity is changed to P1 to P5 in steps S402 to S405 (electron beam pulse condition A) and steps S406 to S409 (electron beam pulse condition B), and the light is emitted from the circular pattern on the sample.
  • the amount of secondary electron signals is displayed as brightness.
  • increasing the irradiation light intensity increases the conductivity of the pattern (lowers the resistance value), and decreases the charge, resulting in an increase in the amount of secondary electron signals (high brightness).
  • the horizontal axis is plotted as the irradiation light intensity and the vertical axis is plotted as the brightness (secondary electron signal amount), the result is as shown in FIG. 5B.
  • the dependence 501 on the irradiation light intensity under the electron beam pulse condition A and the dependence 502 on the irradiation light intensity under the electron beam pulse condition B are different.
  • the electron beam pulse condition B is an example in which the interval time is set longer than that of the electron beam pulse condition A (Tb> Ta), and the electron beam pulse condition B is a sample rather than the electron beam pulse condition A.
  • the brightness increases as the surface potential of the secondary electron signal decreases and the amount of secondary electron signals increases.
  • the difference between the two is remarkable when the irradiation light intensity is medium, but the resistance value is not sufficiently reduced in the region where the irradiation light intensity is weak, and the resistance value is excessively reduced in the region where the irradiation light intensity is strong. As a result, the difference in brightness between the two becomes smaller. Therefore, the brightness difference ⁇ b acquired between these two electron beam pulse conditions is calculated, and the irradiation light intensity Pmax (P3 in the example of FIG. 5B) having the largest difference is selected as the light irradiation condition ⁇ (S410). For the sample structure, it is possible to select a light irradiation condition (sensitivity maximization condition) that maximizes the rate of change in the amount of secondary electron signals with respect to changes in electron beam pulse conditions.
  • FIG. 6 is a plot of the brightness (secondary electron signal amount) acquired in steps S411 to S413 on the vertical axis and the interval time on the horizontal axis. Since the light irradiation condition ⁇ that maximizes the change in brightness with respect to the change in interval time has already been selected in step S410, the minimum necessary interval time is selected here for the purpose of improving the throughput. Therefore, when the interval times Tx and Ty are selected as the electron beam pulse conditions at two points with respect to the preset change amount threshold value bth , the brightness (secondary electron signal amount) obtained under those conditions is Two conditions are selected in which the difference exceeds the change amount threshold bth and the total interval time (Tx + Ty) is the minimum or is equal to or less than the predetermined threshold.
  • the secondary electron signal amount (brightness) is acquired in a round-robin manner, and two conditions satisfying the above-mentioned conditions are selected as the electron beam pulse conditions X and Y.
  • the electron beam pulse condition (electron beam pulse condition A) having the shortest configurable interval time is automatically set as the electron beam pulse condition X, and the electron beam pulse condition Y is set to the electron beam pulse condition X.
  • the interval time it is also possible to select the interval time as short as possible so that the change in brightness exceeds the change amount threshold bth .
  • this series of steps may be performed for all the specified inspection target coordinates on the wafer, or the entire wafer is inspected using only the electron beam pulse condition X or Y, and specific secondary electrons are used.
  • the light irradiation condition ⁇ and the electron beam pulse conditions X and Y may be applied only to the inspection target coordinates indicating the signal amount to obtain the resistance value and the capacitance value.
  • FIG. 7 shows an example of the GUI displayed on the input / output device 115.
  • the GUI includes an electro-optical condition input unit 701, a coordinate input unit 702, a light irradiation condition input unit 703, an electron beam pulse condition input unit 704, a light irradiation condition output unit 705, and an electron beam pulse condition output unit 706.
  • the electron optics condition input unit 701 sets the acceleration voltage, irradiation current, magnification, and the like of the electron beam.
  • the coordinate input unit 702 sets the condition setting coordinates and the inspection target coordinates.
  • the light irradiation condition input unit 703 inputs the light irradiation condition (irradiation light intensity, wavelength, deflection, period, etc.) to be obtained and the set range thereof when the light irradiation condition is obtained.
  • FIG. 7 shows an example in which the light irradiation condition is the irradiation light intensity.
  • the electron beam pulse condition input unit 704 inputs the electron beam pulse condition (interval time, light irradiation-electron beam irradiation delay time, etc.) to be obtained and the set range thereof.
  • FIG. 7 shows an example in which the electron beam pulse condition is set as the interval time.
  • the light irradiation condition output unit 705 and the electron beam condition output unit 706 display the results when light and electron beam are irradiated according to the settings of the light irradiation condition input unit 703 and the electron beam pulse condition input unit 704, respectively.
  • the input to the input units 701 to 704 may be directly input on the GUI, or may be in a format such as reading data saved in a text file or the like saved in advance.
  • the output to the output units 705 and 706 may be directly output as a graph on the GUI, or may be output to a file as data.
  • FIGS. 8A to 8F show an example of the time relationship between electron beam irradiation, light irradiation, and secondary electron detection timing during electron beam scanning.
  • Each figure shows how the irradiation point of the electron beam is shifted in pixel units in the X coordinate direction in the electron beam irradiation of one line. Two-dimensional data can be acquired by repeating this a plurality of times while shifting the position in the Y coordinate direction.
  • both the electron beam and the light are irradiated by all the pixels. By setting the spot diameter of the light to include the range scanned by the electron beam, the light may be irradiated to the observation field at a fixed point.
  • FIG. 8B shows an example in which light is irradiated before and after the electron beam irradiation of one line, and the light is not irradiated at the time of the electron beam irradiation.
  • FIG. 8C shows an example in which light and electron beams are intermittently irradiated at certain intervals, and each interval time I, phase (delay) relationship D, irradiation time width (duty) W, and secondary electrons are shown.
  • Sampling timing (not shown) is a parameter.
  • the amount of secondary electron signals acquired by the image pixels corresponding to the electron beam non-irradiation period is zero or a noise value.
  • the amount of secondary electron signals for all pixels is acquired by repeating the process of shifting the start pixel of the subsequent frame (for example, frame 2) with respect to the start pixel of the preceding frame (for example, frame 1) and acquiring the data. It is possible.
  • FIG. 8D shows an example in which only the electron beam is intermittently irradiated and the light is continuously irradiated.
  • FIG. 8E shows an example in which the electron beam is intermittently irradiated as in FIG. 8D, but the light is irradiated only before and after the irradiation of one line as in FIG. 8B.
  • FIG. 8F is an example in which the electron beam is continuously irradiated and the light is intermittently irradiated, and the time offset of sampling for acquiring the secondary electron signal is used as a parameter with respect to the timing of light irradiation. This makes it possible to specify which time of the transient response to the action of the optical pulse should be captured.
  • the electron beam pulsed condition may include the detection timing condition.
  • the electron beam irradiation timing and the sampling timing for the light irradiation timing may be specified as adjustment parameters as one of the electron beam pulse conditions and the light irradiation conditions.
  • FIGS. 12A to 12D show such an example.
  • FIGS. 12A to 12B show the state of the electron beam or light emitted to the sample when the gate is controlled in a state where the electron source and the light source are continuous.
  • FIGS. 12C to 12D show a state in which the gate is controlled by the blanker 102 or the optical path breaker 110 when the electron source or the light source is oscillating in a pulse. Is irradiated on the sample.
  • One division of the pulse waveform in FIGS. 8C to 8F may be one division of a burst waveform in which pulses of a minute time shown in FIG. 12D are continuous, or may be one continuous pulse waveform shown in FIG. 12B. ..
  • a process of resetting the charged state of the sample may be added when the electron beam pulse condition and the light irradiation condition are switched. For example, after inspecting the wafer by setting a certain light irradiation condition and electron beam pulse condition as shown in FIG. 11 (S1101 to S1103, S1106 to S1107), and before setting the next light irradiation condition and electron beam pulse condition.
  • the charge may be reset by providing a step of carrying out the wafer from the sample chamber 119 (S1104, S1108).
  • FIG. 13A and 13B show an example of a sample having a gate electrode 1301 and a junction electrode 1302, FIG. 13A is a top view, and FIG. 13B is a cross-sectional view.
  • the gate electrode 1301 is connected to the gate 1303, an insulating film 1304 is formed under the gate 1303, and the gate electrode 1301 is arranged on the P-type silicon substrate 1306.
  • the bonding electrode 1302 is connected to a diffusion layer 1305 formed by performing N-type doping in a silicon substrate 1306.
  • a PN junction is formed at the interface between the silicon substrate 1306 and the diffusion layer 1305.
  • the wavelength and energy of light required to eliminate static electricity when charged are different. Therefore, when inspecting the junction electrode 1302, a wavelength long enough not to affect the insulating film 1304 of the gate electrode 1301 may be selected, and when inspecting the gate electrode 1301, a short wavelength may be selected.
  • the electron beam and light irradiation conditions are determined by using the average value of the total secondary electron signal amount or the secondary electron signal amount at a specific location. You may set and inspect structures to be inspected with different structures under the same conditions.
  • step S414 of FIG. 4 the electron beam or light is irradiated to a specific position when the stage is moved to the inspection target coordinates in step S415 or before the condition setting in step S401 is started. May have steps to do.
  • 14A and 14B are examples of a memory array as a sample
  • FIG. 14A is a top view
  • FIG. 14B is a circuit diagram.
  • the sample includes a gate electrode 1401, a drain electrode 1402, and a drain electrode region 1403.
  • the gate electrode 1401 is connected to the gate of the MOS transistor 1404 for connecting the drain electrode 1402 to the wiring 1405.
  • the resistance value from the drain electrode 1402 to the wiring 1405 depends on the potential of the gate electrode 1401. Therefore, when the drain electrode region 1403 and the drain electrode 1402 contained therein are the inspection targets, the gate electrode 1401 is irradiated with the electron beam and the light in advance before the inspection target is irradiated with the electron beam and the light. It is possible to accurately adjust the resistance of the drain electrode 1402 by providing a step for controlling the charging voltage.
  • the potential adjusting means a method of irradiating the gate electrode 1401 with an optical / electron beam while changing the conditions so that the secondary electron signal value of the drain electrode 1402 under a certain electron beam pulse condition becomes a specific value may be used. Then, the potential may be measured as follows to obtain irradiation conditions such that the specified potential is obtained.
  • FIG. 15A illustrates the change in the amount of secondary electron signals depending on the sample potential when the detector 113 has an energy filter.
  • the amount of secondary electron signals emitted when the sample is irradiated with an electron beam shows the distribution as shown in FIG. 15A.
  • VR is the retarding voltage applied to the sample
  • Vs is the surface charging potential of the sample
  • e is 1 electron volt (1 [eV]).
  • the secondary electron signal detection amount is plotted as shown in FIG. 15B while changing the voltage VF of the energy filter in the state of no charge, and the voltage VF1 of the energy filter at the time of observation and the number of detected electrons at that time. It is possible to measure the charge amount Vs as a difference from the voltage VF2 of the energy filter in a non-charged state, which gives the number of detected electrons equal to (brightness).
  • the step of adjusting the resistance value in the inspection area in advance by irradiating the electrodes and areas inside and outside the inspection area with electron beam / light and adjusting the potential is performed. You may add it.
  • FIG. 9 shows a flow in which the irradiation conditions of the light / electron beam in Example 2 are set and the inspection is executed.
  • the arithmetic unit 114 executes this flow.
  • the second embodiment is a flow suitable for the case where the standard electrical characteristics of the sample to be inspected are specified in advance and only the sample showing an outlier is to be detected, for example, in the inspection in the mass production process.
  • the stage moves to the condition setting coordinates (S901).
  • the electron beam pulse conditions A and B specified in advance here, the interval times Ta [seconds] and Tb [seconds], respectively, where Ta ⁇ Tb
  • the secondary electron signal amounts S (Ta) and S. (Tb) is acquired (S902).
  • the acquisition may be performed without irradiation under the condition of the interval time Ta [seconds], and may or may not be irradiated with the light under the condition of the interval time Tb [seconds].
  • the average of the two points S (Ta) and S (Tb), or the value Sm (Ta, Tb) of the intermediate point obtained by substituting into a predetermined calculation formula is obtained (S903).
  • This calculation formula may be, for example, a weighted average of S (Ta) and S (Tb), or may be S (Ta) or S (Tb) itself.
  • the electron beam pulse condition C (here, the interval time Tc [seconds]) is set (S904), and then the light irradiation condition is selected within the range specified in advance (S905).
  • the interval time Tc may be the same as the interval time Ta.
  • the sample pattern with the coordinates for setting the conditions is irradiated with an electron beam to obtain the secondary electron signal amount Sx (Tc) (S906). It is determined whether Sx (Tc) and Sm (Ta, Tb) are equal, and if they are not equal, another light irradiation condition is set, the secondary electron signal amount is acquired again, and the same determination is made (S907). ).
  • a certain standard error range may be specified in advance.
  • the light irradiation condition at that time is saved as the light irradiation condition ⁇ (S908).
  • the stage is moved to the inspection target coordinates (S909), the light irradiation condition ⁇ and the electron beam pulse condition C are set, and the secondary electron signal amount is acquired (S910). Do this at all coordinates to be inspected.
  • the electrical characteristics (resistance, capacity, etc.) at each inspection target coordinate are the resistance value / capacitance value in the reference sample obtained in advance, and the reference sample acquired under the same light irradiation conditions / electron beam irradiation conditions as in step S910.
  • the resistance value / capacitance value at each inspection target coordinate is calculated, displayed or saved based on the secondary electron signal value of the above and the secondary electronic signal value of each inspection target coordinate acquired in step S910 (S911).
  • step S910 It may have a step of displaying the amount of secondary electron signals acquired in step S910 as a heat map. Further, the inspection target coordinates deviated from the reference value by a certain amount or more may be inspected again under different light irradiation conditions and electron beam pulse conditions, and may be branched into a step of obtaining a resistance value and a capacitance value.
  • the interval time is plotted on the horizontal axis as the electron beam pulse condition
  • the brightness is plotted on the vertical axis
  • the irradiation light intensity is plotted as a parameter as the light irradiation condition.
  • the amount of secondary electron signals acquired under the electron beam pulse condition A (interval time Ta) in the state without light irradiation shown by the solid line is the amount of secondary electron signals in the state of the highest resistance, and the charge is large.
  • the amount of secondary electron signals is small.
  • the pulse interval time Ta is 0 seconds (that is, the electron beam is continuously irradiated)
  • the amount of secondary electron signals under the electron beam pulse condition B decreases as the interval time increases, and the amount of secondary electron signals becomes the largest.
  • the interval time Tb decreases as the interval time increases, and the amount of secondary electron signals becomes the largest.
  • the resistance value and capacitance value of the sample are large and the amount of secondary electron signals changes slowly even in the vicinity of the interval time Tb, the sample is irradiated with light of an appropriate wavelength and intensity. By reducing the equivalent resistance value, the maximum value of the amount of secondary electron signals can be obtained.
  • Electron microscope body 101: Electron gun, 102: Blanker, 103: Aperture, 104: Deflection, 105: Objective lens, 106: Sample, 107: Stage, 108: Sample stand, 109: Light source, 110: Optical path blocking Machine, 111: Optical path, 112: Control device, 113: Detector, 114: Computing device, 115: Input / output device, 116: Wafer cassette, 117: Wafer loader, 118: Preparation room, 119: Sample room, 201: Wafer substrate , 202: Insulation film, 203: Floating conductor, 701: Electro-optical condition input unit, 702: Coordinate input unit, 703: Light irradiation condition input unit, 704: Electron beam pulse condition input unit, 705: Light irradiation condition output unit, 706: Electron beam pulse condition output unit, 1301: Gate electrode, 1302: Bonding electrode, 1303: Gate, 1304: Insulation film, 1305:

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