Charged particle beam device, method for setting observation conditions, and program

Abstract

A charged particle beam device, which observes a sample by periodically irradiating the sample with a pulsed charged particle beam, comprises a control device that controls the irradiation of the pulsed charged particle beam and the detection of a signal of emitted electrons on the basis of observation conditions. The control device calculates the irradiation period, scanning speed, and pulse width of the pulsed charged particle beam and the detection timing of the signal of emitted electrons on the basis of the current of the charged particle beam emitted from a particle source, and the capacitance and electrical resistance of the sample, and sets observation conditions including the current of the charged particle beam, the irradiation period, scanning speed, and pulse width of the pulsed charged particle beam, and the detection timing of the emitted electron signal.

Description

[Technical Field]

[0001] The present invention relates to a measuring device that observes a sample using a charged particle beam, and in particular to an electron microscope. [Background technology]

[0002] In the electronics field, the size of semiconductor devices is becoming smaller and more three-dimensional every year, which has led to a demand for information on the electrical properties of semiconductors, not only on their surfaces but also on the structures at the bottom of the diffusion layers.

[0003] One method for observing the surface of a semiconductor is to use a scanning electron microscope, which will also be referred to as an SEM in the following explanation.

[0004] A technique described in Patent Document 1 is known as a method for measuring electrical characteristics using an SEM. Patent Document 1 describes the following: "A measurement device for observing a sample by irradiating it with a charged particle beam, comprising: a particle source for outputting the charged particle beam; a lens for focusing the charged particle beam; a detector for detecting signals of emitted electrons emitted from the sample irradiated with the charged particle beam; and a control device for controlling the output of the charged particle beam and the detection of the emitted electron signals based on observation conditions, wherein the control device sets, as the observation conditions, a first parameter for controlling the irradiation period of the charged particle beam, a second parameter for controlling the pulse width of the pulsed charged particle beam, and a third parameter for controlling the detection timing of the emitted electron signals within the irradiation time of the pulsed charged particle beam, and the third parameter is determined based on the difference in intensity of each of the signals of a plurality of emitted electrons emitted from the irradiation position of the charged particle beam." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-137160 Summary of the Invention [Problem to be solved by the invention]

[0006] The range of electrical properties observable using an SEM (observation range) depends on the observation conditions. One of the observation conditions is the electron beam probe current (probe current). Changing the probe current takes time, which reduces inspection throughput.

[0007] An object of the present invention is to provide a technique for setting observation conditions that realize a desired observation range while keeping the electron beam irradiation current constant. [Means for solving the problem]

[0008] A representative example of the invention disclosed in the present application is as follows: That is, a charged particle beam device for observing a sample by periodically irradiating the sample with a pulsed charged particle beam, the charged particle beam device comprising: a particle source for outputting the charged particle beam; a lens for focusing the charged particle beam; a detector for detecting a signal of emitted electrons emitted from the sample irradiated with the charged particle beam; and a detector for detecting a signal of emitted electrons emitted from the sample irradiated with the charged particle beam based on observation conditions. The aforementioned a control device that controls the irradiation of the charged particle beam and the detection of the signal of the emitted electrons, and holds observation range information for managing an observation range map that indicates the observation accuracy for a combination of the electrical resistance and capacitance of the sample, and the observation range map is managed in association with the irradiation cycle of the charged particle beam and an average irradiation current that is a current irradiated to the sample in one cycle, and the control device specifies the observation range map that allows accurate observation based on the electrical resistance and capacitance of the sample and the observation range map, acquires the irradiation cycle and average irradiation current of the charged particle beam that are associated with the observation range map, and calculates the irradiation cycle and average irradiation current of the charged particle beam that are acquired. Based on The aforementioned charged particle beam Scanning Speed and a pulse width and a detection timing of the emitted electron signal, and the current of the charged particle beam, The aforementioned The observation conditions are set, including the irradiation period, the scanning speed, the pulse width, and the detection timing of the emitted electron signal. [Effects of the Invention]

[0009] According to the present invention, it is possible to set observation conditions that realize a desired observation range while keeping the electron beam irradiation current constant. Objects, configurations, and effects other than those described above will become apparent from the following description of the embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of the configuration of a scanning electron microscope according to a first embodiment. [Figure 2A] 1 is a diagram showing an example of a sample observed using the scanning electron microscope of Example 1. FIG. [Figure 2B] 1 is a diagram showing an example of a sample observed using the scanning electron microscope of Example 1. FIG. [Figure 3A] FIG. 3 is a diagram showing an example of a control signal of the scanning electron microscope of the first embodiment. [Figure 3B] FIG. 3 is a diagram showing an example of a control signal of the scanning electron microscope of the first embodiment. [Figure 4A] FIG. 10 is a diagram illustrating an example of observation range information according to the first embodiment. [Figure 4B] FIG. 10 is a diagram illustrating an example of observation range information according to the first embodiment. [Figure 4C] FIG. 10 is a diagram illustrating an example of observation range information according to the first embodiment. [Figure 5] FIG. 4 is a diagram showing an example of a screen displayed on the output device according to the first embodiment. [Figure 6] 4 is a flowchart illustrating a process executed when the scanning electron microscope of the first embodiment sets observation conditions. [Figure 7] FIG. 10 is a diagram showing an example of a screen displayed on an output device according to the second embodiment. [Figure 8] FIG. 10 is a diagram showing an example of a control signal for the scanning electron microscope of the second embodiment. [Figure 9] FIG. 11 is a diagram showing an example of a screen displayed on an output device according to a third embodiment. [Figure 10] 10 is a flowchart illustrating a process executed when the scanning electron microscope of the third embodiment sets observation conditions. [Figure 11] FIG. 11 is a diagram showing an example of a screen displayed on an output device according to a fourth embodiment. [Figure 12] FIG. 10 is a diagram showing an example of a potential distribution used in an observation simulation in Example 4. [Figure 13] 10 is a flowchart illustrating a process executed when the scanning electron microscope of the fourth embodiment sets observation conditions. [Figure 14] FIG. 10 is a diagram showing an example of the configuration of a scanning electron microscope according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention should not be construed as being limited to the description of the embodiments shown below. Those skilled in the art will readily understand that the specific configuration can be changed without departing from the concept or spirit of the present invention.

[0012] In the configuration of the invention described below, the same or similar configurations or functions are denoted by the same reference numerals, and redundant explanations will be omitted.

[0013] In this specification, the terms "first," "second," "third," etc. are used to identify components and do not necessarily limit the number or order.

[0014] To facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings etc. may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not limited to the position, size, shape, range, etc. disclosed in the drawings etc. [Example]

[0015] Fig. 1 is a diagram showing an example of the configuration of a scanning electron microscope according to Example 1. Figs. 2A and 2B are diagrams showing an example of a sample observed using the scanning electron microscope according to Example 1.

[0016] The scanning electron microscope 10 comprises an electron optical system column 101 , a controller 102 , and a computer 103 .

[0017] The electron optical system column 101 is composed of an electron gun 111 , deflectors 113 and 114 , an aperture 115 , an objective lens 116 , a detector 118 , and a sample holder 117 .

[0018] The electron gun 111 outputs a primary electron beam 112. In the first embodiment, a pulsed electron beam is irradiated onto the sample 119 as the primary electron beam 112. The output of the pulsed electron beam may be realized by controlling a deflector 113 corresponding to a pulsed deflector, or may be realized by using the electron gun 111 capable of outputting a pulsed electron beam.

[0019] The focus and the like of the primary electron beam 112 are adjusted when it passes through a deflector 113 and an objective lens 116. Furthermore, the trajectory of the primary electron beam 112 is deflected when it passes through a deflector 114, and the primary electron beam 112 scans a sample 119 two-dimensionally. Emitted electrons emitted from the sample 119 irradiated with the primary electron beam 112 are detected by a detector 118. The signal of the emitted electrons detected by the detector 118 is processed by a computer 103. A two-dimensional image corresponding to the irradiation position of the primary electron beam 112 is displayed on an output device 124.

[0020] The sample holder 117 includes a stage on which a sample 119 is placed. The stage is capable of tilt control and movement control in three dimensions (X, Y, and Z axes).

[0021] Here, the sample 119 is assumed to be a semiconductor substrate 200 as shown in FIGS. 2A and 2B.

[0022] The semiconductor substrate 200 is composed of a conductor 201, insulators 202 and 203, and a contact plug 204. A netlist representing an equivalent circuit of the device structure of the semiconductor substrate 200 is superimposed on the semiconductor substrate 200.

[0023] The scanning electron microscope 10 of Example 1 can observe not only the electrical characteristics (electrical resistance and capacitance) of a semiconductor substrate 200 with a small number of stacked layers as shown in Fig. 2A, but also the electrical characteristics of a semiconductor substrate 200 with a large number of stacked layers as shown in Fig. 2B. Note that the semiconductor substrate 200 shown in Fig. 2A and Fig. 2B is an example and is not limiting.

[0024] The controller 102 controls each component of the electron optical system column 101 according to instructions from the computer 103. The controller 102 is, for example, a microcomputer or a computer.

[0025] The computer 103 includes an arithmetic unit 121, a storage unit 122, an input unit 123, and an output unit 124. The computer 103 may include a storage medium such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0026] The arithmetic device 121 executes predetermined arithmetic processing in accordance with a program stored in the storage device 122. The arithmetic device 121 is, for example, a central processing unit (CPU), a field programmable gate array (FPGA), or a graphics processing unit (GPU).

[0027] The storage device 122 stores the programs executed by the arithmetic device 121 and data used by the programs. The storage device 122 also includes temporary storage areas such as work areas used by the programs. The storage device 122 may be, for example, a memory. The programs and data stored in the storage device 122 will be described later.

[0028] The input device 123 is a device for inputting data, and includes a keyboard, a mouse, a touch panel, etc. The output device 124 is a device for outputting data, and includes a touch panel, a display, etc.

[0029] The storage device 122 stores programs that implement the calculation module 131 and the simulator 132, and also stores observation range information 133. The storage device 122 may store programs and information not shown.

[0030] The calculation module 131 sets observation conditions for controlling the irradiation of the pulsed electron beam and the detection of the emitted electron signal. The calculation module 131 also generates an image (voltage contrast image) from the emitted electron signal. The calculation module 131 may be divided into multiple modules for each function.

[0031] Here, the observation conditions include the acceleration voltage, the irradiation current (probe current), the pulse width (irradiation time), the irradiation cycle, and the detection timing. Note that the observation conditions may also include elements other than those described above, such as the scan range and the manner in which the primary electron beam 112 is moved.

[0032] The simulator 132 executes a device simulation for estimating the electrical characteristics of the sample 119 and an observation simulation for estimating the signal of emitted electrons. The processing using the simulator 132 will be described in a fourth embodiment.

[0033] The observation range information 133 is information relating to the observation range of the scanning electron microscope 10 .

[0034] 3A and 3B are diagrams showing examples of control signals for the scanning electron microscope 10 of the first embodiment.

[0035] The scanning electron microscope 10 starts scanning from, for example, the upper left of the sample 119 and scans the primary electron beam 112 to the lower left. This makes it possible to control the charge of the sample 119 and observe the transient state of the charge of the sample 119.

[0036] The master clock is a signal that serves as a reference for the operation of each device. The control signals, which will be described later, are controlled to be synchronized with the master clock.

[0037] The pixel represents a pixel in the X direction of the sample 119. A variable representing the interval (split distance) between pixels irradiated with the pulsed electron beam on the sample 119 is denoted as n, and a variable representing the time for one pixel is denoted as T. pix It is written as follows.

[0038] The scanning control signal is a control signal for controlling the deflector 113 to adjust the irradiation position of the primary electron beam 112. Here, a variable representing the scanning speed of the primary electron beam 112 in the X direction is V scn It is written as follows.

[0039] As the scan control signal increases, the primary electron beam 112 moves from the left end to the right end on the sample 119. When the scanning electron microscope 10 reaches the right end, that is, when the intensity of the polarizer control signal changes to its initial value, it moves to scan lines spaced at regular intervals in the Y direction and then irradiates the sample 119 with a pulsed electron beam from the left end to the right end.

[0040] The irradiation control signal is a control signal for irradiating a pulsed electron beam. The irradiation control signal is determined by the irradiation period and pulse width. In the following description, the variable representing the irradiation period is referred to as T ird and the variable representing the pulse width is T pls It is written as follows.

[0041] The detection control signal is a control signal for adjusting the timing for detecting emitted electrons. The computer 103 performs sampling so as to detect emitted electrons once at any timing during irradiation of the pulsed electron beam. The detection control signal is determined by the pre-detection timing and the detection timing. The pre-detection timing represents the time interval from when the pulsed electron beam is irradiated to when detection starts. In FIG. 3B, the pre-detection timing is 0. The detection timing represents the time interval for detecting emitted electrons. In the following, the variable representing the pre-detection timing is defined as T pre_det and the variable representing the detection timing is T pre It is written as follows.

[0042] 4A, 4B, and 4C are diagrams illustrating an example of the observation range information 133 according to the first embodiment.

[0043] The observation range information 133 stores an observation range map 400 as shown in Figures 4A, 4B, and 4C. The observation range map 400 represents the observation accuracy of the scanning electron microscope 10 for combinations of electrical resistance and capacitance. In this figure, the darker the color, the higher the observation accuracy.

[0044] The observation range map 400 is managed in association with the characteristics (device structure, material), irradiation current, irradiation period, and average irradiation current of the sample 119. It is assumed that the characteristics and irradiation current of the sample 119 associated with the observation range maps 400 shown in Figures 4A, 4B, and 4C are the same.

[0045] Here, the average irradiation current represents the current irradiated to the sample 119 in one period, and can be calculated by multiplying the duty ratio by the irradiation current, as in equation (1). ave is a variable that represents the average irradiation current, and I p is a variable representing the emission current.

[0046]

number

[0047] When the probe current is kept constant, it is found that the observation range can be expanded as follows by adjusting the average probe current and the probe period.

[0048] (Characteristic 1) As shown in FIG. 4B, it was found that by increasing the average irradiation current, the capacitance increases and the observation range shifts in the direction of decreasing electrical resistance.

[0049] (Characteristic 2) As shown in FIG. 4C, it was found that by shortening the irradiation period, the observation range shifts in the direction in which the capacitance decreases.

[0050] The calculation module 131 of Example 1 calculates the irradiation period and the average irradiation current from the electrical characteristics of the sample 119, and calculates the parameters of the irradiation control signal (irradiation period, scanning speed, pulse width) and the parameters of the detection control signal (pre-detection timing, detection timing) from the irradiation period and the average irradiation current.

[0051] FIG. 5 is a diagram showing an example of a screen displayed on the output device 124 according to the first embodiment.

[0052] The screen 500 is a screen that is displayed when setting observation conditions, and includes an input button 501 , an input field 502 , a setting button 503 , a display field 504 , an image acquisition button 505 , and a display field 506 .

[0053] The input button 501 is an operation button for instructing calculation of parameters for an irradiation control signal and parameters for a detection control signal using values ​​input in an input field 502. When the input button 501 is operated, the computer 103 executes an observation condition setting process using the values ​​input in the input field 502.

[0054] The input field 502 is a field for inputting values ​​used to calculate parameters of the irradiation control signal and the detection control signal. Specifically, the input field 502 includes boxes for inputting the acceleration voltage, irradiation current, split distance, magnification (pixel distance), capacitance, and electrical resistance.

[0055] The setting button 503 is an operation button for setting observation conditions. When the scanning electron microscope 10 of Example 1 receives an operation of the setting button 503, it irradiates the sample 119 with a pulsed electron beam based on the observation conditions, and records data indicating the time change in the signal of the emitted electrons in the storage device 122. Note that the screen 500 may include a field for displaying a graph of the time change in the signal of the emitted electrons.

[0056] A display field 504 is a field for displaying the calculated parameters of the irradiation control signal and the detection control signal.

[0057] An image acquisition button 505 is an operation button for instructing generation of a voltage contrast image. A display field 506 is an area for displaying a voltage contrast image.

[0058] FIG. 6 is a flowchart illustrating the process executed by the scanning electron microscope 10 of the first embodiment when setting observation conditions.

[0059] When the input button 501 is operated, the scanning electron microscope 10 starts the processing described below.

[0060] The calculator 103 acquires input information including the value entered in the input field 502 (step S101).

[0061] The calculator 103 calculates the irradiation period and average irradiation current of the pulsed electron beam using the capacitance and electrical resistance included in the input information and the observation range information 133 (step S102). Specifically, the following processing is executed.

[0062] (S102-1) The computer 103 identifies the observation range map 400 to be referenced based on the irradiation current included in the input information. Note that if the characteristics (device structure, material) of the sample 119 have been input, that information may also be used.

[0063] (S102-3) The computer 103 refers to the identified observation range map 400 and selects the observation range map 400 with the smallest difference between the center of gravity of the area with the highest accuracy and the combination of capacitance and electrical resistance included in the input information. In other words, the observation range map 400 with the smallest distance between two points in the (capacitance-electrical resistance) space is selected. The computer 103 acquires the irradiation period and average irradiation current associated with the selected observation range map 400.

[0064] This concludes the description of the process in step S102.

[0065] The calculator 103 calculates the scanning speed, pulse width, and detection timing using the irradiation period and average irradiation current (step S103). Specifically, each value is calculated using the following formulas.

[0066] The scanning speed is calculated using, for example, equation (2).

[0067]

number

[0068] The pulse width is calculated using, for example, equation (3).

[0069]

number

[0070] The detection timing is calculated using, for example, equation (4).

[0071]

number

[0072] When the computer 103 receives the operation of the setting button 503, it transmits an observation instruction including the observation conditions to the controller 102, thereby irradiating the sample 109 with a pulsed electron beam (step S104). When the controller 102 receives the observation instruction, it controls the electron optical system column 101 to periodically irradiate the sample 119 with a pulsed electron beam having a predetermined pulse width, and measures the emitted electrons.

[0073] The computer 103 acquires observation results such as data showing the time change of the signal of the emitted electrons detected by the detector 118 via the controller 102 (step S105) and records them in the storage device 122.

[0074] The computer 103 acquires a detection signal by sampling data indicating a time change in the signal of emitted electrons based on the parameters of the detection control signal (step S106). The computer 103 generates a voltage contrast image using the detection signal.

[0075] According to the first embodiment, the parameters of the irradiation control signal (irradiation cycle, scanning speed, pulse width) and the parameters of the detection control signal (pre-detection timing, detection timing) can be calculated using the capacitance and the electrical resistance.

[0076] Furthermore, according to the method of the first embodiment, the observation range can be expanded while keeping the probe current fixed, thereby preventing a decrease in throughput due to changes in the probe current. [Example]

[0077] The second embodiment differs from the first embodiment in that an irradiation mode can be selected when setting observation conditions. The second embodiment will be described below, focusing on the differences from the first embodiment.

[0078] The configuration of the scanning electron microscope 10 of the second embodiment is the same as that of the first embodiment. In the second embodiment, the screen 500 is partially different. Fig. 7 is a diagram showing an example of a screen displayed on the output device 124 of the second embodiment.

[0079] In the second embodiment, two boxes are added to the input field 502. One box is a box for selecting an irradiation mode. In this box, "throughput" and "charge control" are displayed in a pull-down format. The other box is a parameter that can be set when the mode is "charge control." The variable representing this parameter is denoted as Sep. Sep is an integer that is equal to or greater than 1 and equal to or less than the split distance.

[0080] The method for setting observation conditions in the second embodiment is the same as that in the first embodiment, but the mathematical formulas are partially different. Specifically, in the second embodiment, the mathematical formula for calculating the pulse width is given by Equation (5).

[0081]

number

[0082] The other formulas are the same as those in the first embodiment.

[0083] 8 is a diagram showing an example of a control signal for the scanning electron microscope 10 of Example 2. In charge control, it is possible to make the charge state on the sample 119 uniform. However, since the SN value decreases, the throughput slows down.

[0084] According to the second embodiment, the observation conditions can be set according to the irradiation mode. [Example]

[0085] In the third embodiment, the method of inputting the capacitance and the electrical resistance is different from that in the first embodiment. The third embodiment will be described below, focusing on the differences from the first embodiment.

[0086] The configuration of the scanning electron microscope 10 of the third embodiment is the same as that of the first embodiment. However, the computer 103 does not need to hold the observation range information 133.

[0087] In the third embodiment, the screen 500 is partially different. Fig. 9 is a diagram showing an example of a screen displayed on the output device 124 in the third embodiment.

[0088] In the third embodiment, the input field 502 includes a box for specifying a desired observation range instead of boxes for inputting capacitance and electrical resistance. The user sets the desired observation range in the graph in the box. The desired observation range may also be set numerically.

[0089] In the third embodiment, the calculator 103 performs calculations using the capacitance and electrical resistance corresponding to the center of gravity of the set observation range. The calculations are the same as those in the first embodiment.

[0090] The following modifications are also possible: Fig. 10 is a flowchart illustrating the process executed by the scanning electron microscope 10 of the third embodiment when setting observation conditions.

[0091] The processes from step S101 to step S106 are the same as those in the first embodiment.

[0092] In step S107, the computer 103 determines whether or not the desired result has been obtained (step S107).

[0093] For example, the computer 103 calculates the electrical properties of the sample 109 from the detection signal and determines whether they are within a desired observation range. If the electrical properties are not within the desired observation range, the computer 103 determines that the desired results have not been obtained.

[0094] If the desired result is not obtained, the computer 103 returns to step S102 and calculates the irradiation cycle and average irradiation current. Specifically, the computer 103 determines the direction to move to include the desired observation range based on the electrical characteristics calculated from the detection signal. The computer 103 adjusts the irradiation cycle and average irradiation current under the current observation conditions based on the deviation of the electrical characteristics and characteristics 1 and 2, and further calculates parameters of the irradiation control signal (irradiation cycle, scanning speed, pulse width) and parameters of the detection control signal (pre-detection timing, detection timing) using the adjusted irradiation cycle and average irradiation current.

[0095] If the desired results are obtained, the computer 103 ends the process.

[0096] According to the third embodiment, the parameters of the irradiation control signal (irradiation cycle, scanning speed, pulse width) and the parameters of the detection control signal (pre-detection timing, detection timing) can be calculated based on the input of the desired observation range. [Example]

[0097] In Example 4, the method of inputting the capacitance and the electrical resistance and the method of setting the observation conditions are different from those in Example 1. Hereinafter, Example 4 will be described, focusing on the differences from Example 1.

[0098] The configuration of the scanning electron microscope 10 of the fourth embodiment is the same as that of the first embodiment. However, the computer 103 does not need to hold the observation range information 133.

[0099] In the fourth embodiment, the screen 500 is partially different. Fig. 11 is a diagram showing an example of a screen displayed on the output device 124 in the fourth embodiment.

[0100] The input field 502 of the fourth embodiment includes a box for inputting the device structure of the sample 109 instead of the boxes for inputting the capacitance and the electrical resistance.

[0101] In the fourth embodiment, the computer 103 performs a device simulation using the device structure to calculate a netlist, and then calculates the capacitance and the electrical resistance based on the netlist.

[0102] Furthermore, the input field 502 of the fourth embodiment includes boxes for inputting simulation setting information (yield, charging influence distance, electric field on the sample, secondary electron energy distribution) for performing observation simulation.

[0103] In the fourth embodiment, an observation simulation is performed using an energy distribution model of emitted electrons in which a potential saddle point occurs due to the surface potential caused by charging.

[0104] FIG. 12 is a diagram showing an example of the potential distribution used in the observation simulation of the fourth embodiment.

[0105] In the model shown in FIG. 12, when a pulsed electron beam is irradiated onto the sample 119, a surface potential V s The electric field in the Z direction of the sample 119 interacts with the surface potential to form a potential saddle point V φThe potential saddle point is a negative potential relative to the surface potential, and therefore acts as an energy barrier for the emitted electrons. The energy barrier is given as the difference between the potential saddle point and the surface potential. As the surface potential increases, the emission current (signal strength) of the emitted electrons decreases, and the charging ability decreases.

[0106] At this time, the emitted electron current I se is defined by equation (6).

[0107]

number

[0108] Here, β is a variable representing a characteristic parameter of the energy distribution of emitted electrons, and σ is a variable representing the yield.

[0109] When an equivalent circuit corresponding to the sample 119 is connected to a pulsed electron beam controlled based on equation (6), the current source corresponds to the emission current of the emitted electrons, making it possible to perform observational simulations. For example, by modeling the contact plug of the semiconductor substrate as a parallel circuit, it is possible to simulate the time change in the emission current of the emitted electrons based on the electrical characteristics of the contact plug.

[0110] FIG. 13 is a flowchart illustrating the process executed by the scanning electron microscope 10 of the fourth embodiment when setting observation conditions.

[0111] The calculator 103 acquires input information including the value entered in the input field 502 (step S201).

[0112] The computer 103 calculates the electrical characteristics by executing a device simulation using the device structure of the sample 109 included in the input information (step S202).

[0113] The computer 103 sets the initial observation conditions (step S203).

[0114] The acceleration voltage, probe current, split distance, and magnification are determined from the input information. Other parameters are determined randomly or based on an arbitrary algorithm. The parameter ranges may be specified in advance.

[0115] The computer 103 executes an observation simulation based on the observation conditions and the simulation setting information included in the input information (step S204).

[0116] The computer 103 determines whether or not the desired result has been obtained based on the electrical characteristics calculated from the netlist and the electrical characteristics obtained from the observation simulation (step S205). For example, the computer 103 determines that the desired result has been obtained when the error between the two electrical characteristics is smaller than a threshold value.

[0117] If the desired results are not obtained, the computer 103 updates the observation conditions based on the electrical characteristics calculated from the netlist and the electrical characteristics obtained from the observation simulation (step S206), and then returns to step S204.

[0118] Specifically, the computer 103 can grasp the direction in (capacitance-electrical resistance) space to bring the electrical characteristics obtained from the observation simulation closer to the electrical characteristics calculated from the netlist. The computer 103 adjusts the irradiation cycle and average irradiation current under the current observation conditions based on the deviation of the electrical characteristics and characteristics 1 and 2, and further calculates parameters of the irradiation control signal (irradiation cycle, scanning speed, pulse width) and parameters of the detection control signal (pre-detection timing, detection timing) using the adjusted irradiation cycle and average irradiation current.

[0119] In this way, by using characteristics 1 and 2, the observation conditions can be adjusted efficiently and quickly.

[0120] If the desired observation results are not obtained, the computer 103 ends the process.

[0121] According to the fourth embodiment, even when the characteristics of the sample 119 are unknown and the observation range map 400 does not exist, the observation conditions can be appropriately set. [Example]

[0122] In the fifth embodiment, the configuration of the scanning electron microscope 10 is different from that of the first embodiment. Hereinafter, the fifth embodiment will be described, focusing on the differences from the first embodiment.

[0123] FIG. 14 is a diagram showing an example of the configuration of a scanning electron microscope 10 according to a fifth embodiment.

[0124] In the fifth embodiment, the scanning electron microscope 10 does not include the computer 103. The scanning electron microscope 10 communicates with the computer 103 via a network 104. The computer 103 can be replaced with, for example, a cloud system.

[0125] In the fifth embodiment, the computer 103 displays a screen 500 on the scanning electron microscope 10 and receives input. After acquiring input information via the screen 500, the computer 103 executes the processes from step S102 to step S106.

[0126] The computer 103 may perform any of the processes in the second to fourth embodiments.

[0127] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments are provided to explain the present invention in detail, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, some of the configurations of each embodiment can be added to, deleted from, or replaced with other configurations.

[0128] Furthermore, the above-described configurations, functions, processing units, processing means, etc. may be partially or entirely implemented in hardware, for example, by designing them as integrated circuits. The present invention can also be realized by software program code that implements the functions of the embodiments. In this case, a storage medium on which the program code is recorded is provided to a computer, and a processor included in the computer reads the program code stored in the storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiments, and the program code itself and the storage medium on which it is stored constitute the present invention. Examples of storage media for providing such program code include flexible disks, CD-ROMs, DVD-ROMs, hard disks, solid-state drives (SSDs), optical disks, magneto-optical disks, CD-Rs, magnetic tapes, non-volatile memory cards, and ROMs.

[0129] Furthermore, the program code that realizes the functions described in this embodiment can be implemented in a wide range of program or script languages, such as assembler, C / C++, perl, Shell, PHP, Python, and Java.

[0130] Furthermore, the program code of the software that realizes the functions of the embodiments may be distributed via a network and stored in a storage means such as a computer's hard disk or memory, or in a storage medium such as a CD-RW or CD-R, and the processor of the computer may read and execute the program code stored in the storage means or storage medium.

[0131] In the above-described embodiment, the control lines and information lines are shown as those considered necessary for the explanation, and not all control lines and information lines are necessarily shown in the product. All components may be interconnected.

Claims

1. A charged particle beam device for observing a sample by periodically irradiating the sample with a pulsed charged particle beam, a particle source that outputs the charged particle beam; a lens for focusing the charged particle beam; a detector for detecting a signal of emitted electrons emitted from the sample irradiated with the charged particle beam; a control device that controls the irradiation of the charged particle beam and the detection of the emitted electron signal based on observation conditions, the control device holds observation range information for managing an observation range map that indicates observation accuracy for a combination of electrical resistance and capacitance of the sample; the observation range map is managed in association with an irradiation cycle of the charged particle beam and an average irradiation current, which is a current irradiated onto the sample in one cycle; The control device identifying the observation range map that allows accurate observation based on the electrical resistance and capacitance of the sample and the observation range map; acquiring the irradiation period and the irradiation average current of the charged particle beam associated with the observation range map; calculating a scanning speed and a pulse width of the charged particle beam and a detection timing of a signal of the emitted electrons based on the acquired irradiation period of the charged particle beam and the acquired average irradiation current; a scanning speed of the charged particle beam, a pulse width of the charged particle beam, and a detection timing of the emitted electron signal;

2. A charged particle beam device according to claim 1, The control device Accepting input of parameters for controlling the charged state of the sample; a scanning speed and a pulse width of the charged particle beam, and a detection timing of a signal of the emitted electrons, based on the acquired irradiation period of the charged particle beam, the acquired average irradiation current, and the parameters.

3. A charged particle beam device for observing a sample by periodically irradiating the sample with a pulsed charged particle beam, comprising: a particle source that outputs the charged particle beam; a lens for focusing the charged particle beam; a detector for detecting a signal of emitted electrons emitted from the sample irradiated with the charged particle beam; a control device that controls the irradiation of the charged particle beam and the detection of the emitted electron signal based on observation conditions, The control device a first process of calculating an irradiation period, a scanning speed, and a pulse width of the pulsed charged particle beam and a detection timing of a signal of the emitted electrons based on a current of the charged particle beam irradiated from the particle source and an electrical resistance and a capacitance of the sample; a second process of setting the observation conditions including the current, the irradiation cycle, the scanning speed, and the pulse width of the charged particle beam, and the detection timing of the emitted electron signal; In the first process, the control device Calculating the electrical resistance and capacitance of the sample based on the device structure of the sample; setting the observation conditions and simulating observation of the sample; a charged particle beam device characterized in that the observation conditions are updated by changing the irradiation period of the charged particle beam under the current observation conditions and the irradiation average current, which is the current irradiated to the sample in one period, based on the error between the calculated electrical resistance and capacitance of the sample and the electrical resistance and capacitance of the sample obtained by the simulation.

4. A method for setting observation conditions for a charged particle beam device that periodically irradiates a sample with a pulsed charged particle beam and observes the sample, comprising: The charged particle beam device includes: a particle source that outputs the charged particle beam; a lens for focusing the charged particle beam; a detector for detecting a signal of emitted electrons emitted from the sample irradiated with the charged particle beam; a control device that controls the irradiation of the charged particle beam and the detection of the emitted electron signal based on observation conditions, the control device holds observation range information for managing an observation range map that indicates observation accuracy for a combination of electrical resistance and capacitance of the sample; the observation range map is managed in association with an irradiation cycle of the charged particle beam and an average irradiation current, which is a current irradiated onto the sample in one cycle; The method for setting the observation conditions includes: a first step in which the control device calculates the irradiation period, scanning speed, and pulse width of the charged particle beam and the detection timing of the emitted electron signal based on the current of the charged particle beam irradiated from the particle source and the electrical resistance and capacitance of the sample; a second step in which the control device sets the observation conditions including the current, the irradiation cycle, the scanning speed, and the pulse width of the charged particle beam, and the detection timing of the emitted electron signal, The first step comprises: a third step in which the control device specifies the observation range map that allows accurate observation based on the electrical resistance and capacitance of the sample and the observation range map; a fourth step in which the control device acquires the irradiation period and the irradiation average current of the charged particle beam associated with the observation range map; a fifth step in which the control device calculates the scanning speed and pulse width of the charged particle beam and the detection timing of the emitted electron signal based on the acquired irradiation period of the charged particle beam and the acquired average irradiation current.

5. A method for setting observation conditions according to claim 4, comprising: the first step includes a step of receiving, by the control device, an input of a parameter for controlling a charged state of the sample; The fifth step is a method for setting observation conditions, characterized in that it includes a step in which the control device calculates the scanning speed and pulse width of the charged particle beam and the detection timing of the emitted electron signal based on the acquired irradiation period of the charged particle beam, the acquired average irradiation current, and the parameters.

6. A method for setting observation conditions for a charged particle beam device that periodically irradiates a sample with a pulsed charged particle beam and observes the sample, comprising: The charged particle beam device includes: a particle source that outputs the charged particle beam; a lens for focusing the charged particle beam; a detector for detecting a signal of emitted electrons emitted from the sample irradiated with the charged particle beam; a control device that controls the irradiation of the charged particle beam and the detection of the emitted electron signal based on observation conditions, The method for setting the observation conditions includes: a first step in which the control device calculates an irradiation period, a scanning speed, and a pulse width of the charged particle beam and a detection timing of a signal of the emitted electrons based on the current of the charged particle beam irradiated from the particle source and the electrical resistance and capacitance of the sample; a second step in which the control device sets the observation conditions including the current, the irradiation cycle, the scanning speed, and the pulse width of the charged particle beam, and the detection timing of the emitted electron signal, The first step comprises: the control device calculating the electrical resistance and capacitance of the sample based on the device structure of the sample; the control device setting the observation conditions and simulating observation of the sample; and updating the observation conditions by the control device by changing the irradiation period of the charged particle beam under the current observation conditions and the irradiation average current, which is the current irradiated to the sample in one period, based on the error between the calculated electrical resistance and capacitance of the sample and the electrical resistance and capacitance of the sample obtained by the simulation.

7. A program to be executed by a computer for setting observation conditions of a charged particle beam device that periodically irradiates a pulsed charged particle beam to observe a sample, comprising: The charged particle beam device includes: a particle source that outputs the charged particle beam; a lens for focusing the charged particle beam; a detector for detecting a signal of emitted electrons emitted from the sample irradiated with the charged particle beam; a control device that controls the irradiation of the charged particle beam and the detection of the emitted electron signal based on observation conditions, the computer holds observation range information for managing an observation range map that indicates the observation accuracy for a combination of the electrical resistance and capacitance of the sample; the observation range map is managed in association with an irradiation cycle of the charged particle beam and an average irradiation current, which is a current irradiated onto the sample in one cycle; The program a first step of calculating the irradiation period, scanning speed, and pulse width of the charged particle beam and the detection timing of the emitted electron signal based on the current of the charged particle beam irradiated from the particle source and the electrical resistance and capacitance of the sample; a second step of setting the observation conditions including the current, the irradiation cycle, the scanning speed, and the pulse width of the charged particle beam, and the detection timing of the emitted electron signal; The first step comprises: a third step of identifying the observation range map that allows accurate observation based on the electrical resistance and capacitance of the sample and the observation range map; a fourth step of acquiring the irradiation period and the irradiation average current of the charged particle beam associated with the observation range map; and a fifth step of calculating the scanning speed and pulse width of the charged particle beam and the detection timing of the emitted electron signal based on the acquired irradiation period of the charged particle beam and the acquired average irradiation current.

8. A program according to claim 7, the first step includes a step of receiving an input of a parameter for controlling a charged state of the sample; The fifth step is a program characterized by including a step of calculating the scanning speed and pulse width of the charged particle beam and the detection timing of the emitted electron signal based on the acquired irradiation period of the charged particle beam, the acquired average irradiation current, and the parameters.

9. A program to be executed by a computer for setting observation conditions of a charged particle beam device that periodically irradiates a sample with a pulsed charged particle beam and observes the sample, comprising: The charged particle beam device includes: a particle source that outputs the charged particle beam; a lens for focusing the charged particle beam; a detector for detecting a signal of emitted electrons emitted from the sample irradiated with the charged particle beam; a control device that controls the irradiation of the charged particle beam and the detection of the emitted electron signal based on observation conditions, The program a first step of calculating an irradiation period, a scanning speed, and a pulse width of the charged particle beam and a detection timing of a signal of the emitted electrons based on a current of the charged particle beam irradiated from the particle source and an electrical resistance and a capacitance of the sample; a second step of setting the observation conditions including the current, the irradiation cycle, the scanning speed, and the pulse width of the charged particle beam, and the detection timing of the emitted electron signal; The first step comprises: calculating the electrical resistance and capacitance of the sample based on the device structure of the sample; setting the observation conditions and simulating observation of the sample; and a procedure for updating the observation conditions by changing the irradiation cycle of the charged particle beam under the current observation conditions and the average irradiation current, which is the current irradiated to the sample in one cycle, based on an error between the calculated electrical resistance and capacitance of the sample and the electrical resistance and capacitance of the sample obtained by the simulation.

Images