Inspection system

Abstract

An inspection step S04 includes: a plurality of point irradiation steps S12 for irradiating an irradiation point set according to the inspection pattern with a pulse charged particle beam obtained by pulsating a charged particle beam; and at least one irradiation position deviation correction step S11 for correcting the deflection amount of the pulse charged particle beam set for each irradiation point so that the inspection pattern is irradiated with the pulse charged particle beam in the point irradiation steps. In the irradiation position deviation correction step, the correction amount of the deflection amount of the pulse charged particle beam is determined on the basis of the profile of the detection signal acquired by emitting the charged particle beam so as to cross the boundary of the inspection pattern corresponding to the irradiation point in at least one direction.

Description

Inspection System

[0001] The present invention relates to an inspection system that inspects the electrical characteristics of an inspection pattern formed on a sample using a charged particle beam.

[0002] Patent Document 1 relates to a beam scanning inspection device that performs inspection by scanning a charged particle beam, and discloses a method or device for measuring and correcting positional deviations of the beam deflection scanning position or the detection pixel position during inspection with high precision in a short time by measuring positional deviations based on image data obtained by actually scanning the charged particle beam.

[0003] Patent No. 4186464

[0004] One known sample analysis method using a charged particle beam device is the pump-probe method, in which an electron beam is irradiated onto a test pattern formed on a sample, and the electrical characteristics of the test pattern are inspected from the transient response of the surface potential of the test pattern.

[0005] The pump-probe method involves an inspection step in which pump and probe pulses are irradiated onto numerous irradiation points set in correspondence with numerous inspection patterns contained within the field of view of the charged particle beam device. Therefore, depending on the number of inspection patterns, the inspection step takes a long time. During this inspection step, localized charging and de-charging by the charged particle beam is repeated, causing the charged state on the sample to constantly change. Furthermore, the sample is placed on a sample stage, and sample stage drift may occur during long inspection times.

[0006] Therefore, even if the charged particle beam is deflected by the deflection amount of the charged particle beam for each irradiation point determined at the start of the inspection step, there is a risk that the beam may be irradiated at a position that is shifted from the target inspection pattern.

[0007] The present invention has been made in consideration of the above, and one of its objects is to provide an inspection system that can suppress deviation of the irradiation position of a charged particle beam due to charging or the like during inspection of a large number of inspection patterns.

[0008] An inspection system according to one embodiment of the present invention is an inspection system comprising a charged particle beam device and a computer system, wherein a plurality of inspection patterns to be inspected are formed on a sample, and the computer system is configured to control an inspection sequence including an inspection step of inspecting electrical characteristics of the plurality of inspection patterns included in the field of view of the charged particle beam device, and the charged particle beam device comprises a charged particle optical system that irradiates the sample with a charged particle beam, a detection system that detects signal electrons emitted when the sample is irradiated with the charged particle beam and outputs a detection signal according to the amount of detected signal electrons, and a control system that controls the charged particle optical system under the control of the computer system and outputs the detection signal to the computer system, and the inspection step includes detecting a pulsed charged particle beam obtained by pulsing the charged particle beam. The method includes a plurality of point irradiation steps in which the pulsed charged particle beam is irradiated onto irradiation points set corresponding to the inspection pattern, and one or more irradiation position deviation correction steps in which the amount of deflection of the pulsed charged particle beam set for each irradiation point is corrected so that the pulsed charged particle beam is irradiated onto the inspection pattern in the point irradiation steps. The computer system calculates electrical characteristics of the inspection pattern corresponding to the irradiation point based on detection signals obtained by irradiating the irradiation point with a pump pulse and a probe pulse in the point irradiation step, and determines an amount of correction for the amount of deflection of the pulsed charged particle beam based on profiles of detection signals obtained by irradiating the irradiation point with the charged particle beam so as to cross the boundary of the inspection pattern corresponding to the irradiation point in one or more directions in the irradiation position deviation correction step.

[0009] The present invention provides an inspection system that can appropriately inspect the electrical characteristics of inspection patterns by suppressing deviations in the irradiation position of a charged particle beam due to charging or the like during inspection of a large number of inspection patterns. Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

[0010] 1 is a diagram showing an example of the configuration of an inspection system; FIG. 2 is a cross-sectional view of an example of a sample; FIG. 3 is a diagram showing a pulsed electron beam irradiation sequence by a pump-probe method; FIG. 4 is a plan view of an example of a sample; FIG. 5 is an inspection sequence executed by an inspection system; FIG. 6 is a flowchart of an inspection step of Example 1; FIG. 7 is an example of electron beam irradiation for correcting an irradiation position deviation; FIG. 8 is an example of electron beam irradiation for correcting an irradiation position deviation; FIG. 9 is a diagram for explaining irradiation position deviation correction; FIG. 10 is an example of an irradiation position set at an irradiation point in Example 2; FIG. 11 is a flowchart of an inspection step of Example 1; FIG. 12 is an example of an irradiation current waveform of a pump pulse and a detection signal waveform thereof; FIG. 13 is an example of an irradiation current waveform of a probe pulse and a detection signal waveform thereof; FIG. 14 is an example of electron beam irradiation with a pump pulse or a probe pulse; FIG. 15 is an example of electron beam irradiation with a pump pulse or a probe pulse; FIG. 16 is an example of electron beam irradiation with a pump pulse or a probe pulse;

[0011] An example configuration of an inspection system is shown in Figure 1. The imaging unit (electron microscope main body) 100 preferably has a light irradiation system for irradiating light onto a sample, in addition to the elements that make up a typical electron microscope, such as an electron optical system, a stage mechanism system, a control system, and a detection system.

[0012] The electron optical system includes an electron gun 111, a blanker 112, an aperture 113, an image-shift deflector 114, and an objective lens 115. The electron beam emitted from the electron gun 111, which is controlled by an electron gun controller 121, is pulsed by the blanker 112 and aperture 113, which are controlled by a blanking controller 122, and the pulsed electron beam 101 is focused on the sample 104 by the objective lens 115, which is controlled by an objective lens controller 125. The irradiation position of the pulsed electron beam 101 on the sample 104 can be controlled by the image-shift deflector 114, which is controlled by a deflector controller 124. Although not shown here, a scanning deflector and its controller for two-dimensionally scanning the electron beam on the sample 104 are also provided.

[0013] Signal electrons emitted from the sample 104 upon irradiation with the pulsed electron beam 101 are detected by the detector 117, and the signal processing unit 127 outputs a detection signal corresponding to the amount of the signal electrons.

[0014] The stage mechanism system has a sample stage 116 that is movable in the X, Y, and Z axes, and the sample 104 is placed on the sample stage 116. Although not shown, a retarding power supply for applying a voltage to the sample 104 may be connected. The sample stage 116 is moved by a stage controller 126.

[0015] The light irradiation system 118, controlled by a light irradiation system control unit 128, irradiates the sample 104 with light 103 through a window 119 provided in the lens barrel. The light irradiation system 118 includes a light source, a shutter, and an optical path (not shown), and the continuous light or pulsed light emitted from the light source is gated by the shutter to control the irradiation of the sample 104. The light from the light source is focused on the sample 104 by the optical path. The optical path may include general optical elements such as mirrors, lenses, and splitters, as well as optical fibers. The wavelength of the light 103 is set, for example, in the range from ultraviolet light to infrared light (350 to 1000 nm).

[0016] The controllers and the like that control the various elements of the imaging unit 100 are collectively referred to as the control system 120. The control device 150 sends control signals to the control system 120 to cause the imaging unit 100 to execute processing. Control of the imaging unit 100 includes, for example, control of the acceleration voltage, irradiation current amount, and irradiation position of the electron beam, as well as control of the wavelength, intensity, and focusing position of the light. It also includes control of synchronizing the pulsing timing of the electron beam, the ON / OFF timing of the light, and the sampling timing of the signal electrons. The control device 150 is connected to an input / output device 151, and inspection conditions and the like are input by the user via the input / output device 151. The input / output device 151 is implemented as a display, keyboard, mouse, switches on a control panel, etc.

[0017] The control device 150 also measures electrical characteristics based on the amount of signal electrons acquired by the detector 117 and outputs the results to the input / output device 151. The control device 150 may be a stand-alone computer, or may be connected to other computers or data storage devices via a network to distribute the computational load. Here, a stand-alone computer and multiple computers capable of distributing and executing computational loads are collectively referred to as a computer system. The control device 150 is a function of the computer system that constitutes the inspection system of this embodiment.

[0018] The inspection performed by the inspection system of this embodiment will be described with reference to Figures 2A and 2B. Figure 2A is a cross-sectional view of an example of a sample 104. A MOS structure having a drain 202, a source 203, a gate insulating film 204, and a gate electrode 205 is formed on a substrate 201, and a plug 206, which is an inspection pattern, is connected to the drain 202. The MOS structure is also covered with an insulating film 207, and the upper surface of the plug 206 is exposed from the insulating film 207. At this time, an equivalent resistance R and an equivalent capacitance C exist between the plug 206 and the source 203, as shown in the figure.

[0019] 2B shows the change in the surface potential of the plug 206 when the plug 206 is irradiated with a pulsed electron beam 210. When the incident electrons cause a positive charge, the surface potential of the plug 206 increases during the irradiation period of the pulsed electron beam, whereas the surface potential of the plug 206 decreases during the period when the pulsed electron beam is turned off due to a current flowing in accordance with the discharge time constant determined by the equivalent resistance R and equivalent capacitance C described above.

[0020] On the other hand, when the surface potential of the plug 206 increases, the electric field directly above it changes, generating a potential barrier, which causes low-energy signal electrons, among the signal electrons that have been emitted, to be returned again toward the plug 206. For this reason, the higher the surface potential, the lower the amount of signal electrons detected by the detector 117, and the lower the surface potential, the higher the amount of signal electrons detected by the detector 117. Therefore, it is possible to capture changes in the charge of the plug 206 from the amount of signal electrons detected by the detector 117 and obtain information about the electrical characteristics of the plug 206, such as the discharge time constant.

[0021] 2B shows a pulsed electron beam irradiation sequence using the pump-probe method. First, a pump pulse 221 is irradiated onto the plug 206. The time width of the pump pulse 221 is set to a value sufficient to saturate the surface potential of the plug 206. Then, a probe pulse 222 is irradiated onto the plug 206. The probe pulse 222 is irradiated multiple times at predetermined time intervals. The electrical characteristics of the plug 206 can be inspected from the change in the amount of signal electrons when the probe pulse 222 is irradiated onto the plug 206, i.e., the change in the surface potential.

[0022] As explained above, in the pump-probe method, electrical characteristics are determined by measuring the surface potential of the test pattern (plug 206), so the charged state of the sample surface affects the test accuracy. For this reason, it is desirable for the test system to be equipped with a light irradiation system that controls the charged state of the sample surface. For example, the sample surface can be neutralized by irradiating it with ultraviolet light, or the surface potential of the sample surface can be controlled to a desired state by irradiating it with light of a longer wavelength.

[0023] FIG. 3 is a plan view of the sample 104, with plugs 206, which are the inspection pattern, appearing on the sample surface. The inspection system of this embodiment measures electrical characteristics by irradiating a pulsed electron beam onto each plug 206 to be inspected, which is included in one field of view. In FIG. 3, the irradiation points to be irradiated with the pulsed electron beam are indicated by crosses, and the irradiation order is indicated by arrows. The irradiation point can be set, for example, as the center position of the plug 206 to be inspected. The irradiation order is not limited to the order shown, as long as it allows efficient irradiation of multiple irradiation points included in the field of view.

[0024] FIG. 4 shows an inspection sequence for the inspection system to inspect the electrical characteristics of the plug 206 shown in FIG. 3 . First, the control device 150 moves the sample stage 116 using the stage controller 126 according to position information of the plug 206 to be inspected (S01), and acquires an SEM image including the plug 206 to be inspected (S02). The SEM image is an image obtained by two-dimensionally scanning the sample surface without pulsing the electron beam, such as the image shown in FIG. 3 . Next, the position information of the plug 206 to be inspected is converted into the deflection amount of the image-shift deflector 114 (S03). Since the center of the SEM image acquired in step S02 is the point where the sample 104 intersects with the optical axis of the electron optical system, the deflection amount of the image-shift deflector 114 when irradiating the pulsed electron beam can be calculated based on the direction and distance of the plug 206 to be inspected relative to the center position of the SEM image. The SEM image acquired in step S02 is called a centering image, and the process in step S03 is called coordinate calibration. Thereafter, a pulsed electron beam is irradiated to each of the plugs 206 to be inspected (plugs marked with an x ​​indicating the irradiation point in FIG. 3) in accordance with the irradiation sequence shown in FIG. 2B, and an inspection of the electrical characteristics is carried out (S04).

[0025] In the inspection step (S04), the plug 206 to be inspected, i.e., each of the irradiation points, needs to be correctly irradiated with the pulsed electron beam. However, there is a risk that the charged state of the sample 104 changes during the inspection, and even though the pulsed electron beam is irradiated with the deflection amount determined in the coordinate calibration step (S03), the pulsed electron beam may actually be irradiated at a position that is shifted from the target inspection pattern. For example, the irradiation position of the pulsed electron beam may be shifted from the irradiation point due to factors such as charging caused by acquiring a centering image, charging caused by irradiating a nearby irradiation point with the pulsed electron beam, charge removal or charging caused by light irradiation from the light irradiation system 118, and drift of the sample stage 116 that occurs during the inspection period.

[0026] Therefore, in Example 1, as shown in FIG. 5, in the inspection step (S04), in addition to irradiating the irradiation points with a pulsed electron beam (point irradiation i step S12-i (1≦i≦N), where N is the number of irradiation points included in one field of view (centering image)), an irradiation position deviation correction step S11 is performed to correct the deflection amount determined in the coordinate calibration step (S03). In the inspection step (S04), irradiation position deviation correction is performed one or more times, and the frequency and timing of performing the irradiation position deviation correction are determined arbitrarily and set as one of the inspection conditions.

[0027] 6A shows an example of electron beam irradiation for correcting the irradiation position deviation. The example of electron beam irradiation for correcting the irradiation position deviation is superimposed on an SEM image 300 of an inspection pattern. The SEM image 300 includes a plug image 301 (corresponding to the plug 206) and an insulating film image 302 (corresponding to the insulating film 207), and a high-brightness area called a white band 303 appears at the boundary between the two. In the irradiation position deviation correction, the position of the inspection pattern on the sample 104 is actually measured by irradiating the sample with an electron beam, and the irradiation position deviation is corrected by comparing the measured position with the position information of the plug 206 used in the coordinate calibration step (S03). In this example, the position of the white band 303, which has a large difference in brightness from the surrounding area, is used as an index to correct the irradiation position deviation.

[0028] Misalignment correction irradiation example 1 is an example in which spot irradiation is performed while shifting the irradiation position along two different directions so as to straddle the boundary of the inspection pattern. Here, a spot irradiation row 311 along the X direction and a spot irradiation row 312 along the Y direction are illustrated. FIG. 7 shows, for example, the amount of signal electrons detected by the detector 117 upon irradiation with the spot irradiation row 311, with the horizontal axis representing the deflection amount of the deflector and the vertical axis representing brightness. Profile 321 is obtained as a fitting curve of brightness discretely obtained by spot irradiation. Meanwhile, profile 322 is a brightness profile in a centering image along the line of spot irradiation row 311. The difference between profile 321 and profile 322 indicates the magnitude of misalignment due to charging or other reasons. In the example of FIG. 7 , the magnitude of the deflection amount determined based on profile 322 is corrected based on difference 323. By performing this correction on the profiles of detection signals acquired along multiple directions, the irradiation position misalignment can be corrected.

[0029] The control device 150 may store a plurality of correction amount candidates in advance, and one of the plurality of correction amount candidates may be selected. Causes of positional deviation include charging and neutralization of the entire field of view, localized charging, and factors other than charging, such as drift of the sample stage 116. Therefore, the cause of positional deviation that requires correction is estimated according to the irradiation of the charged particle beam and / or light in one or more point irradiation steps (S12) performed before the irradiation position deviation correction step (S11), and a correction amount candidate is selected based on the estimated cause of positional deviation.

[0030] Example 1 of irradiation for misalignment correction using spot irradiation is just one example. For example, example 2 of irradiation for misalignment correction, in which the electron beam is linearly scanned along two different directions so as to straddle the boundary of the inspection pattern, can also correct the irradiation misalignment. Figure 6A illustrates linear scanning 313 along the X direction and linear scanning 314 along the Y direction. Furthermore, example 3 of irradiation for misalignment correction, in which a two-dimensional area 315 including a part or the entire inspection pattern is scanned, can also correct the irradiation misalignment. It is desirable that the two-dimensional area 315 be a relatively narrow area so as not to significantly affect the charged state of the sample 104.

[0031] In Fig. 6A, misalignment correction is performed in two directions because the inspection pattern is circular, but depending on the inspection pattern, misalignment correction may be performed in one direction. Fig. 6B shows an example of an inspection pattern that is a line pattern. Misalignment correction irradiation example 4 is an example of spot irradiation performed while shifting the irradiation position so as to straddle the boundary of the line pattern. Because the line pattern extends in the Y direction, a spot irradiation row is formed along the X direction. Similarly, misalignment correction irradiation example 5 is an example of linearly scanning the electron beam so as to straddle the boundary of the line pattern.

[0032] In addition, in Figure 7, a brightness profile in a centering image is shown as an example of the profile 322 to be compared, but if the position information of the plug 206 used in the coordinate calibration step (S03) is design data (e.g., CAD data indicating a chip pattern), it can be compared with the design data.

[0033] In the pump-probe method, a single irradiation point is irradiated with a pulsed electron beam multiple times, as shown in FIG. 2B. Therefore, if the pulsed electron beam drifts during the irradiation sequence for a single irradiation point due to charging or other reasons, there is a risk that the plug 206 to be inspected will not be irradiated with the beam during the irradiation sequence. Therefore, as shown in FIG. 8, different irradiation positions 401 are set for a single irradiation point (inspection pattern). FIG. 8 shows an example in which four irradiation positions 401-1 to 4 are set for a single irradiation point, and the irradiation positions 401-1 to 4 are set as positions shifted in the Y+ direction, X+ direction, Y- direction, and X- direction from the center of the inspection pattern (plug), respectively.

[0034] In the second embodiment, as shown in Fig. 9, in the inspection step (S04), point irradiation i (1 ≤ i ≤ N) is performed as point irradiation with drift determination S13. In point irradiation with drift determination S13, an electron beam is irradiated onto one irradiation point while changing the irradiation position 401. Note that in the flow of Fig. 9, the irradiation position deviation correction step S11 described in the first embodiment is first performed, mainly to correct position deviation due to charging accompanying acquisition of the centering image. This step can be omitted.

[0035] The irradiation sequence in point irradiation with drift determination S13 will be described using Figures 10A and 10B. Figure 10A shows the irradiation current waveform of a pump pulse 501 and the detection signal waveform 502 of the detector 117. Because the pump pulse 501 is a pulse with a relatively long time width, it is configured as a set of short pulses that are continuously irradiated, and the irradiation position of the short pulses sequentially rotates among irradiation positions 401-1 to 401-4. Figure 10B shows the irradiation current waveform of a probe pulse 511 and the detection signal waveform 512 of the detector 117. Because the probe pulse 511 is a pulse with a relatively short time width, the irradiation position of the probe pulse 511 sequentially rotates among irradiation positions 401-1 to 401-4.

[0036] The detection signal waveforms shown in Figures 10A and 10B illustrate an example in which the irradiation position of the pulsed electron beam shown in Figure 8 drifts in the X-direction. In the example of Figure 10A, when a short pulse is irradiated at irradiation position 401-4, the detection signal waveform 502 indicates an outlier with respect to the fitting waveform 503 indicated by the dashed line, which allows us to estimate that irradiation position 401-4 deviates from the inspection pattern. Similarly, in the example of Figure 10B, when a probe pulse is irradiated at irradiation position 401-4, the detection signal waveform 512 indicates an outlier with respect to the fitting waveform 513 indicated by the dashed line, which allows us to estimate that irradiation position 401-4 deviates from the inspection pattern. Note that instead of using a fitting waveform to detect outliers, a normal detection signal waveform acquired at another irradiation point may also be used.

[0037] When an outlier is detected in the detection signal waveform, the control device 150 can perform the following processing.

[0038] (1) Correcting the Misalignment of the Pulsed Electron Beam Irradiation Position For example, in the example of FIG. 10A , the outlier 504 indicates that the irradiation position of the pulsed electron beam has drifted in the X− direction. Therefore, feedback 509 is performed to shift the irradiation position of the pulsed electron beam by a predetermined amount in the X+ direction. This makes it possible to suppress the occurrence of outliers in the detection signal waveform. The direction of the position misalignment correction is determined based on the irradiation position at which the outlier occurred. FIG. 10A shows an example in which an outlier occurred at irradiation position 401-4. However, if outliers occurred at irradiation positions 401-3 and 401-4, it would be understood that the irradiation position of the pulsed electron beam has drifted in the X− direction and the Y− direction. Therefore, feedback 509 is performed to shift the irradiation position of the pulsed electron beam by a predetermined amount in the X+ direction and the Y+ direction. The amount of feedback control may be a fixed amount, or may be determined according to the amount of deviation of the outlier, as will be described later.

[0039] (2) Calculating electrical characteristics by correcting the influence of outliers. The occurrence of outliers reduces the amount of current irradiated onto the test pattern. By calculating the amount of deviation of the outlier from the difference between the detected signal waveform and the fitting waveform and correcting the amount of current irradiated onto the test pattern, the calculation accuracy of the electrical characteristics of the test pattern can be improved.

[0040] (3) Calculation of Feedback Control Amount The feedback control amount may be calculated from the change in the outlier amount of the outlier. For example, the amount of drift occurring at the timing when feedback control is performed is estimated from the change in the outlier amount ε1 for the outlier 504 and the outlier amount ε2 for the outlier 505 (see FIG. 10A ), and a correction amount is calculated to offset the magnitude of the drift. Note that when estimating the amount of drift, the magnitude of the outlier amount is affected by the transient response, so the effect of the transient response must be taken into consideration.

[0041] Furthermore, the relationship between the change in the deviation amount of the outlier and the feedback control amount may be learned. It is considered that the drift of the pulsed electron beam also changes in different ways depending on the cause. By learning the relationship between the change in the deviation amount of the outlier and the feedback control amount, it is expected that the calculation of the correction amount will be more accurate.

[0042] 11A to 11D show examples of pump pulse or probe pulse irradiation in point irradiation with drift determination S13. The example in FIG. 8 shows an example in which electron beam spot irradiation is performed while changing the irradiation position within the inspection pattern, and FIGS. 11A and 11B are variations thereof. FIG. 11A shows an example in which the number of irradiation positions (indicated by + signs in the figure) at which spot irradiation is performed within the inspection pattern is three. Having at least three positions makes it possible to correct the irradiation position deviation for the inspection pattern, which is a two-dimensional pattern. On the other hand, when the inspection pattern can be considered to be substantially a one-dimensional pattern, such as a line pattern, as shown in FIG. 11B, the number of irradiation positions (indicated by + signs in the figure) at which spot irradiation is performed within the inspection pattern may be two.

[0043] Fig. 11C shows an example of irradiation in which an electron beam is scanned to trace a predetermined trajectory 601 within the inspection pattern. Even with this irradiation method, if a portion of the trajectory 601 extends beyond the inspection pattern, an outlier occurs in the detection signal waveform, making it possible to correct the deviation in the irradiation position of the pulsed electron beam. Fig. 11D shows an example of irradiation in which a two-dimensional region 602 included in the inspection pattern is scanned. For example, by dividing the two-dimensional region 602 into four quadrants, it becomes possible to estimate and correct the direction and amount of deviation in the irradiation position of the pulsed electron beam depending on the balance of the magnitude of the detection signal amounts in the divided regions.

[0044] The above embodiments and modifications have been described in detail to make the present invention easier to understand, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment or modification with the configuration of another embodiment or modification, and it is also possible to add the configuration of another embodiment or modification to the configuration of one embodiment or modification. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment or modification with other configurations.

[0045] 100: imaging unit, 101: pulsed electron beam, 103: light, 104: sample, 111: electron gun, 112: blanker, 113: aperture, 114: image shift deflector, 115: objective lens, 116: sample stage, 117: detector, 118: light irradiation system, 119: window, 120: control system, 121: electron gun controller, 122: blanking controller, 124: deflector controller, 125: objective lens controller, 126: stage controller, 127: signal processing unit, 128: light irradiation system control unit, 150: control device, 151: input / output device, 201: substrate, 202: drain, 203: source, 204: gate insulator Insulating film, 205: gate electrode, 206: plug, 207: insulating film, 210: pulsed electron beam, 221: pump pulse, 222: probe pulse, 300: SEM image, 301: plug image, 302: insulating film image, 303: white band, 311, 312: spot irradiation row, 313, 314: linear scanning, 315: two-dimensional area, 321, 322: profile, 323: difference, 401: irradiation position, 501: pump pulse, 502, 512: detection signal waveform, 503, 513: fitting waveform, 509: feedback, 511: probe pulse, 601: trajectory, 602: two-dimensional area.

Claims

1. An inspection system comprising a charged particle beam device and a computer system, wherein a plurality of inspection patterns to be inspected are formed on a sample, and the computer system is configured to control an inspection sequence including an inspection step of inspecting electrical characteristics of the plurality of inspection patterns included in a field of view of the charged particle beam device, the charged particle beam device comprising: a charged particle optical system that irradiates the sample with a charged particle beam; a detection system that detects signal electrons emitted when the sample is irradiated with the charged particle beam and outputs a detection signal according to the amount of detected signal electrons; and a control system that controls the charged particle optical system under the control of the computer system and outputs the detection signal to the computer system, the inspection step including a plurality of point irradiation steps in which the charged particle beam is pulsed to irradiate irradiation points set corresponding to the inspection pattern with a pulsed charged particle beam, and one or more irradiation position deviation correction steps that correct the deflection amount of the pulsed charged particle beam set for each irradiation point so that the pulsed charged particle beam is irradiated onto the inspection pattern in the point irradiation step, and the computer system an inspection system that calculates electrical characteristics of the inspection pattern corresponding to the irradiation point based on the detection signals obtained by irradiating the irradiation point with a pump pulse and a probe pulse in the point irradiation step, and determines a correction amount for the deflection amount of the pulsed charged particle beam based on a profile of the detection signals obtained by irradiating the charged particle beam so as to cross the boundary of the inspection pattern corresponding to the irradiation point in one or more directions in the irradiation position deviation correction step.

2. An inspection system according to claim 1, wherein the inspection sequence includes a centering image acquisition step and a coordinate calibration step, wherein in the centering image acquisition step, the charged particle beam device scans the charged particle beam on the sample to acquire a centering image including a plurality of the inspection patterns, and in the coordinate calibration step, the computer system calculates the amount of deflection of the pulsed charged particle beam for each irradiation point from the centering image.

3. An inspection system according to claim 1, wherein the charged particle beam device comprises a light irradiation system that irradiates the sample with light, and the control system controls the light irradiation system in accordance with the control of the computer system.

4. An inspection system according to claim 3, wherein the computer system stores in advance a plurality of correction amount candidates for the deflection amount of the pulsed charged particle beam, and selects one of the plurality of correction amount candidates for each irradiation position deviation correction step.

5. An inspection system as claimed in claim 4, wherein the computer system selects one of the plurality of correction amount candidates in the irradiation position deviation correction step in accordance with the irradiation of the charged particle beam and / or the light in one or more point irradiation steps carried out before the irradiation position deviation correction step.

6. An inspection system according to claim 1, wherein in the irradiation position deviation correction step, the charged particle beam device performs one of the following irradiations: a first irradiation in which the charged particle beam is spot irradiated while shifting the irradiation position so as to cross the boundary of the inspection pattern; a second irradiation in which the charged particle beam is linearly scanned so as to cross the boundary of the inspection pattern; and a third irradiation in which the charged particle beam is two-dimensionally scanned so as to include all or part of the inspection pattern, thereby obtaining a profile of the detection signal.

7. An inspection system comprising a charged particle beam device and a computer system, wherein a plurality of inspection patterns to be inspected are formed on a sample, and the computer system is configured to control an inspection sequence including an inspection step of inspecting electrical characteristics of the plurality of inspection patterns included in a field of view of the charged particle beam device, the charged particle beam device comprising: a charged particle optical system that irradiates the sample with a charged particle beam; a detection system that detects signal electrons emitted when the sample is irradiated with the charged particle beam and outputs a detection signal according to the amount of detected signal electrons; and a control system that controls the charged particle optical system under the control of the computer system and outputs the detection signal to the computer system, the inspection step including a plurality of point irradiation steps in which the charged particle beam is pulsed to irradiate an irradiation point set corresponding to the inspection pattern with a pulsed charged particle beam, and the computer system calculates the electrical characteristics of the inspection pattern corresponding to the irradiation point based on the detection signals obtained by irradiating the irradiation point with a pump pulse and a probe pulse in the point irradiation step, An inspection system configured such that the pump pulse or the probe pulse at the irradiation point is irradiated while moving among a plurality of irradiation positions on the inspection pattern corresponding to the irradiation point.

8. An inspection system according to claim 7, wherein the computer system determines the drift direction of the charged particle beam based on the irradiation position of the inspection pattern when an outlier occurs in the waveform of the detection signal acquired by irradiating the pump pulse or the probe pulse.

9. An inspection system according to claim 8, wherein the computer system determines a correction amount for the deflection amount of the pulsed charged particle beam set for each irradiation point so as to offset drift of the charged particle beam.

10. An inspection system according to claim 8, wherein the computer system calculates the electrical characteristics of the inspection pattern corresponding to the irradiation point by correcting the influence of the outlier.

11. An inspection system according to claim 7, wherein in the point irradiation step, the charged particle beam device performs one of the following irradiations: a first irradiation for spot irradiation of the charged particle beam while changing the irradiation position within the inspection pattern; a second irradiation for scanning the charged particle beam so as to draw a predetermined trajectory within the inspection pattern; and a third irradiation for scanning the charged particle beam two-dimensionally so as to be included in the inspection pattern, thereby irradiating the pump pulse or the probe pulse.

12. An inspection system according to claim 7, wherein the inspection step includes one or more irradiation position deviation correction steps for correcting the deflection amount of the pulsed charged particle beam set for each irradiation point so that the pulsed charged particle beam is irradiated onto the inspection pattern in the point irradiation step, and the computer system determines the correction amount for the deflection amount of the pulsed charged particle beam based on a profile of the detection signal acquired by irradiating the charged particle beam so that it crosses the boundary of the inspection pattern corresponding to the irradiation point in one or more directions in the irradiation position deviation correction step.

13. An inspection system according to claim 12, wherein the inspection sequence includes a centering image acquisition step and a coordinate calibration step, wherein in the centering image acquisition step, the charged particle beam device scans the charged particle beam on the sample to acquire a centering image including a plurality of the inspection patterns, and in the coordinate calibration step, the computer system calculates the amount of deflection of the pulsed charged particle beam for each irradiation point from the centering image.

14. An inspection system according to claim 12, wherein in the irradiation position deviation correction step, the charged particle beam device performs any one of a fourth irradiation in which the charged particle beam is spot irradiated while shifting the irradiation position so as to cross the boundary of the inspection pattern, a fifth irradiation in which the charged particle beam is linearly scanned so as to cross the boundary of the inspection pattern, and a sixth irradiation in which the charged particle beam is scanned two-dimensionally so as to include all or part of the inspection pattern, thereby acquiring a profile of the detection signal.

15. An inspection system according to claim 7, wherein the charged particle beam device comprises a light irradiation system that irradiates the sample with light, and the control system controls the light irradiation system in accordance with the control of the computer system.

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