Charged particle beam device and measurement method

Abstract

The purpose of the present invention is to control a charged portion according to the structure of a transistor formed on a semiconductor material, and thereby, to measure the on / off characteristics of the transistor by irradiation with a charged particle beam and light. A charged particle beam device according to the present invention turns on a transistor formed on a semiconductor material by irradiating the gate of the transistor with a charged particle beam, and initializes charges possessed by the transistor by irradiating the transistor with the light, thereby controlling the conductive state of the transistor (see fig. 4).

Description

[Technical Field]

[0001] The present invention relates to a technique for measuring a sample by irradiating it with a charged particle beam. [Background technology]

[0002] Charged particle beam instruments such as electron microscopes and ion microscopes are used to observe various samples with fine structures. For example, for the purpose of process control in the manufacturing process of semiconductor devices, a scanning electron microscope, which is one type of charged particle beam instrument, is used to measure the dimensions of semiconductor device patterns formed on semiconductor wafers, which serve as samples, and to inspect for defects.

[0003] The following Patent Document 1 describes an example of a technique for measuring a sample by irradiating the sample with a charged particle beam. The document also describes that the charged state of the sample is controlled by irradiating the sample with a light beam in addition to the charged particle beam. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US7205539 Summary of the Invention [Problem to be solved by the invention]

[0005] When semiconductor devices (e.g., transistors) are formed on semiconductor materials, it is sometimes necessary to control the charge state at specific locations on the device. For example, by turning the gate of a specific transistor on and off, it is sometimes possible to measure the transistor's on / off characteristics (how much electrical signal is required to turn it on / off). Such measurements are typically performed by electrically connecting measurement probes to the device.

[0006] It is thought that a similar measurement could be performed by controlling the charge state of a semiconductor device (i.e., by controlling the amount of charge held by the semiconductor device). However, in conventional technologies such as those described in Patent Document 1, it is not possible (or is not considered) to arbitrarily select the location for charge control according to the structure of the semiconductor device. Therefore, in conventional technologies, it is difficult to measure the ON / OFF characteristics of a semiconductor device by irradiating it with a charged particle beam and light.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to measure the ON / OFF characteristics of a transistor by irradiating it with a charged particle beam and light, by controlling the charged locations according to the structure of the transistor formed on a semiconductor material. [Means for solving the problem]

[0008] The charged particle beam device of the present invention controls the conductive state of a transistor by irradiating a gate of the transistor formed on a semiconductor material with a charged particle beam to turn the transistor ON, and by irradiating the transistor with light to initialize the charge held by the transistor. [Effects of the Invention]

[0009] According to the charged particle beam device of the present invention, the ON / OFF characteristics of a transistor can be measured by irradiating it with a charged particle beam and light by controlling the charged location according to the structure of the transistor formed on the semiconductor material. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing the configuration of a charged particle beam device 1 according to a first embodiment. [Figure 2] Four configuration examples of the light source 131 and the light adjusting unit 132 are shown. [Figure 3] 10 is a flowchart illustrating a procedure for observing a sample 122 by the charged particle beam device 1. [Figure 4] 10A and 10B are diagrams illustrating a method for controlling the charged state of a transistor formed over a sample 122 by light irradiation. [Figure 5] 10 is an example of an in-plane distribution created by the calculation unit 148 in S108. [Figure 6] 10A and 10B are diagrams illustrating an example of operation when the charged particle beam device 1 measures parasitic capacitance between gates of a transistor. [Figure 7] 10 is a flowchart illustrating a procedure for observing a sample 122 by the charged particle beam device 1. [Figure 8] 10 is an example of a user interface that is presented by the calculation unit 148 via the display unit 155. DETAILED DESCRIPTION OF THE INVENTION

[0011] <First Embodiment> 1 is a block diagram showing the configuration of a charged particle beam device 1 according to embodiment 1 of the present invention. The charged particle beam device 1 includes an electron optical system 11, a stage mechanism system 12, a light irradiation system 13, a control system 14, and an operation system 15.

[0012] The electron optical system 11 is composed of an electron gun 111, a deflector 112, an electron lens 113, and an electron detector 114. The stage mechanism system 12 is composed of an XYZ stage 121 on which a sample 122 is placed. The interior of the housing of the electron optical system 11 is controlled to a high vacuum, and the stage mechanism system 12 is installed therein. The light irradiation system 13 includes a light source 131 and a light adjustment unit 132, and light is irradiated onto the sample 122 via a light introduction unit 133. The control system 14 is composed of an electron gun control unit 1411, a deflection signal control unit 142, an electron lens control unit 143, a detector control unit 144, a stage position control unit 145, a light control unit 146, a control message unit 147, and a calculation unit 148. The control message unit 147 writes control values ​​to each control unit based on input information input from a sequence control unit 151.

[0013] An electron beam accelerated by an electron gun 111 is focused by an electron lens 113 and irradiated onto a sample 122. The irradiation position on the sample 122 is controlled by a deflector 112. The electron beam is controlled in accordance with the acceleration voltage, irradiation current, deflection conditions, and electron lens conditions set by a measurement item setting unit 152.

[0014] The control message unit 147 is a functional block that controls the components of the charged particle beam device 1. The control message unit 147 sends operational commands to the detector control unit 144, the electron gun control unit 141, and the like, based on, for example, observation conditions input from the sequence control unit 151. Each control message system controls the stage mechanism system 12 and moves the sample 122 to a predetermined position, based on, for example, light and electron conditions input from the sequence control unit 151. The control message unit 147 controls the detection process of emitted electrons by the electron detector 114 by controlling the supply of power and control signals to the electron detector 114 via the detector control unit 144. Based on the conditions input in the measurement item setting unit 152, the control message unit 147 sends information on light irradiation conditions, such as wavelength, light intensity, and irradiation timing, to the light control unit 146, thereby controlling the operations of the light source 131, the light adjustment unit 132, and the like. More specifically, for example, the light control unit 146 controls the light intensity and wavelength of the light irradiated from the light source 131. The light control unit 146 instructs the light adjustment unit 132 to adjust the traveling direction and polarization of the light emitted from the light source 131. The light control unit 146 may be implemented, for example, by manual operation, or may be implemented, for example, by a program executed on a personal computer equipped with a processor such as a CPU. The control message unit 147 may be configured, for example, by an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0015] Light emitted from the light source 131 is irradiated onto a position on the surface of the sample 122 via the light introduction section 133. In this embodiment, a laser capable of irradiating multiple wavelengths or a laser capable of irradiating a single wavelength is installed as the light source 131 for each required wavelength. The light introduction section 133 has a slit configuration, and the light shape can be controlled arbitrarily. This makes it possible to control the irradiation location depending on the irradiation location and pattern.

[0016] In addition to the above, the operation system 15 also includes an output unit 154 and a display unit 155. The output unit 154 outputs the processing results of the calculation unit 148 in, for example, an appropriate data format. The display unit 155 displays the processing results of the calculation unit 148 on, for example, a screen of a user interface described below.

[0017] The device information input unit 153 of the operation system 15 is a block with the function of inputting the structure and circuit information of the sample to be observed. By inputting CAD information and other information used in the device pattern design, the size of each pattern and electrical circuit information are associated, and the irradiation position of the electron beam and light is controlled accordingly. The input format of the pattern circuit information and size is not particularly specified as long as it provides information such as the pattern coordinates, circuit information, and connection relationships of each pattern. For example, CAD data or text data that indicates the coordinates and circuit structure may be used. Circuit specification for each pattern is possible even without using CAD data. An example of the specification procedure is as follows: (1) An SEM image of the inspection area is acquired; (2) The signal obtained from the electron detector 114 is converted into gradation information by the processing unit and calculation unit, and the image is displayed on the display unit 155 via the output unit 154; (3) The user classifies each pattern type on the GUI (described later) and sends the information to the device information input unit 153. This flow also allows specifying the type of each pattern at the observation position.

[0018] The measurement item setting unit 152 references the device information input by the device information input unit 153 and generates the light and electron beam conditions required to achieve the inspection items specified on the GUI. The sequence control unit 151 creates a measurement sequence based on the light and electron beam conditions set by the measurement item setting unit 152. The sequence control unit 151 generates an irradiation sequence and sends an instruction signal to the control system. When the test item to be inspected is selected by the measurement item setting unit 152, an irradiation sequence of light and electron beam is generated. At this time, the user can also customize the light and electron beam conditions on the GUI, which will be described later. By selecting the sequence visualization button on the GUI, the flow of the light and electron beam irradiation sequence can also be visually confirmed. The user may also set the irradiation timing of light and electron beam as desired.

[0019] The control message unit 147 controls the detector control unit 144, the electron gun control unit 141, the deflection signal control unit 142, the electron lens control unit 143, the stage position control unit 145, the light control unit 146, etc. in accordance with the sequence specified by the sequence control unit.

[0020] The light control unit 146 controls light parameters such as the wavelength, irradiation amount, and peak power of light. The light control unit 146 includes a light source 131 and a light adjustment unit 132. The light source 131 may be a white light source, a semiconductor diode laser, a solid-state laser, or other types of light. The light adjustment unit 132 adjusts the light parameters, such as the light amount, wavelength, polarization plane, irradiation angle onto the sample, pulsed laser / CW (continuous wave) laser, and repetition rate (in the case of a pulsed laser). The light adjustment unit 132 also has the function of controlling and irradiating the light irradiation timing according to the sequence information generated by the measurement item setting unit 152 and the sequence control unit 151. The mechanism having the light irradiation timing function may be a mechanical shutter, an electro-optical element or an acousto-optical element for blocking, or another mechanism capable of realizing optical switching control.

[0021] The electron optical system 11 irradiates an electron beam under the acceleration voltage, irradiation current, deflection conditions, and electron lens conditions set by the measurement item setting unit 152. The timing of electron beam irradiation is controlled by controlling the timing of irradiation and non-irradiation based on the sequence generated by the measurement item setting unit 152 and the sequence control unit 151. The electron beam accelerated by the electron gun 111 is focused by the electron lens 113 and irradiated onto the sample 122. The position at which the electron beam is irradiated onto the sample 122 and the observation magnification are controlled by the deflector 112.

[0022] FIG. 2 shows four configuration examples of the light source 131 and the light adjustment unit 132. In the first configuration example, the light source 131 includes two light sources, 7a and 7b. The laser emitted from the light source 7b is reflected by a reflecting mirror 300 and a beam splitter 61 and merges with the optical path of the laser emitted from the light source 7a. The light sources 7a and 7b may emit light of the same wavelength, or the irradiation output may be adjusted for each wavelength. To adjust the irradiation amount for each wavelength, an attenuator 63, composed of an ND filter or the like with an adjustable light attenuation amount, is installed in the optical path of each wavelength. Similarly, an optical attenuator is used as an optical system for controlling the average output. The light adjustment unit 132 may be a pulse picker using an electro-optical element or a magneto-optical element to control the pulse frequency or the number of pulse irradiations. The light adjustment unit 132 may be a pulse dispersion control optical system composed of a prism pair to control the pulse width. The light adjustment unit 132 may be a light focusing lens to control the irradiation area of ​​the light pulse. The amount of irradiation at each wavelength is detected by an irradiation light detector 62 set in the middle of the optical path. As an example of the irradiation light detector 62, a photodetector type or a thermal type may be used to measure the amount of irradiation.

[0023] 2, multiple wavelengths are generated from a single light source 7a using a wavelength converter 64 made of a nonlinear optical crystal or the like. Attenuators 63 are provided in each optical path so that the irradiation amount of the seed light and SHG (Secondary Harmonic Generation) light can be adjusted.

[0024] The third configuration example in Figure 2 shows the optical path configuration when using a laser capable of irradiating multiple wavelengths from a single laser. The fourth configuration example in Figure 2 shows the optical path configuration when using a light source having multiple wavelength components, such as a white light source. In order to select multiple wavelengths from the white light source, the optical path is split into two by a beam splitter 61. Multiple wavelengths are generated by installing a filter 69 that matches the wavelength to be irradiated. The filter 69 is an optical filter such as a bandpass filter or a notch filter.

[0025] 3 is a flowchart illustrating the procedure for observing the sample 122 using the charged particle beam device 1. Each step in FIG. 3 will be explained below. In this explanation, the ON state of a transistor is defined as a state in which charge is supplied to the gate portion up to the gate voltage when a specified current flows between the source and drain, and the OFF state of a transistor is defined as a state in which the voltage due to the charge on the gate portion is equal to or lower than the gate threshold voltage.

[0026] (Figure 3: Step S100) The control and command unit 147 determines the type, pattern, and inspection items of the device to be inspected. The device type and device pattern data may be specified from CAD data or information obtained by actually observing an SEM image at the observation position.

[0027] (Figure 3: Step S101) The control message unit 147 specifies the location of the device pattern to be observed, the field of view size, the number of chips to be inspected, etc. (observation range) based on the device pattern and chip layout.

[0028] (Figure 3: Step S102) The control and command unit 147 sets the range of the charge amount to be injected and the light irradiation conditions. Regarding the electron beam to be irradiated, the irradiation energy of the electron beam to be injected into the specified pattern, the minimum and maximum values ​​of the charge, and the step amount are determined. In this case, the electron beam conditions for injection into the pattern and the electron beam conditions for observation do not need to be the same. These electron beams may be output from the same electron source and electron optical system, or may be output from different electron sources and optical systems. Alternatively, an electron beam output from a single electron source may be split into multiple electron beams, each of which may be controlled and irradiated separately.

[0029] (Figure 3: Step S102: Supplement) In this step, the recommended light irradiation conditions are set according to the inspection items input and selected in S100. Based on the information input in S100, the light wavelength, irradiation amount, and irradiation timing calculated by the sequence control unit 151 are output to the light control unit 146 according to the inspection items and device inspection range set in the measurement item setting unit 152. If the conditions are sufficient, the user checks, for example, the "Confirm Light Conditions" button on the GUI. If corrections are necessary, the user corrects the light irradiation conditions in the light condition input unit displayed on the GUI, and when the light conditions are decided, presses the "Confirm Light Conditions" button. The light control unit 146 controls the light irradiation conditions according to the light conditions decided in "Confirm Light Conditions."

[0030] (Figure 3: Step S103) The control message unit 147 starts the measurement according to the inspection and measurement items set in steps S100 to S102.

[0031] (Figure 3: Step S104) The light control unit 146 stabilizes or equalizes the initial charged state of the sample 122 and controls the potential by irradiating light onto the sample 122. For example, if transistors are formed in a lattice pattern on the sample 122 (semiconductor material), the observation position is first scanned along the X direction to measure the ON / OFF state of the transistor at each observation position (a specific example of measuring the ON / OFF state based on the observation image will be described later). Next, the observation position is moved by one line in the Y direction. Each time the observation position is moved by one line in the Y direction, the light control unit 146 irradiates light that resets the charged state of only the drain (and source).

[0032] (Figure 3: Step S104: Supplement) In addition to the above, when this step is performed for the first time, the light control unit 146 may irradiate light that resets the charged state of the gate. Specific examples of light that resets only the drain and light that resets the gate will be described later.

[0033] (Figure 3: Step S105) The electron optical system 11 injects charge into the sample 122 by irradiating the sample 122 with an electron beam. The charge injection conditions are set in S102. The amount of charge injection is changed by a step width each time this step is performed. This step width is set in S102. The gate of the transistor becomes charged according to the amount of charge injection, resulting in a state similar to that in which a voltage is applied to the gate. By measuring at what stage the transistor turns on while changing the amount of charge injection, the ON / OFF characteristics (gate threshold voltage (Vth) characteristics) of the transistor can be measured.

[0034] (Figure 3: Step S105: Supplement) The following modifications are possible. Photoelectron emission by light irradiation may be used as a means for storing charge in the gate portion. When the gate portion is made of polysilicon, photoelectrons are emitted from the gate portion by irradiating it with light of a wavelength having optical energy equal to or greater than the ionization energy of silicon, or by irradiating it with light of a peak intensity sufficient to cause multiphoton excitation, thereby generating a positive charge. This positive charge may be used to turn on the gate. Therefore, step S105 in FIG. 3 may be a means for irradiating light. The amount of charge to be stored may be controlled by optical parameters such as the light irradiation dose, irradiation time, peak intensity, and wavelength.

[0035] (Figure 3: Step S106) The electron optical system 11 moves the field of view to the observation position and irradiates the sample with an electron beam under the electron optical conditions set in S103. Electrons emitted from the sample are detected by the detector 114. The calculation unit 148 generates an observation image of the observation position using the detection signal output by the detector 114. The observation image is output as data or on a GUI via the output unit 154 and the display unit 155. If the observation position is the same as the charge injection position in S105, it is not necessary to move the irradiation position in S105 to S106. If they are not the same, the observation position can be moved by moving the stage, shifting the deflection of the electron beam, or the like.

[0036] (Figure 3: Loop part) The control message unit 147 repeats S104 to S106 until the number of steps set in S102 is completed.

[0037] (Figure 3: Steps S107 to S108) The calculation unit 148 acquires the brightness level of the observed image for each amount of charge injected into the sample 122 (S107). The calculation unit 148 performs this process for each observation position on the sample 122. This makes it possible to obtain an in-plane distribution of the amount of injected charge and the brightness level (S108). A specific example of the in-plane distribution will be described later.

[0038] FIG. 4 is a diagram illustrating a method for controlling the charge state of a transistor formed on a sample 122 by light irradiation. The transistor has a source, a gate, and a drain. In this embodiment, the structure of an n-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) will be used for explanation. An n-type MOSFET is formed by forming a silicon oxide film in the gate region on a p-type silicon substrate and then forming a gate metal on the oxide film. When a positive voltage is applied to the gate portion formed between the source and drain of an n-type MOSFET, an inversion layer (n-type) is formed between the drain and source.

[0039] When using an electron beam to operate and inspect n-type MOSFETs, irradiating the gate with an electron beam in a region where the secondary electron yield is greater than 1 results in electrons being emitted from the sample in excess of the number of incident electrons, resulting in a positive charge. This positive charge applies a positive potential to the gate, turning it on and generating a flow of electrons between the source and drain. In contrast, in the case of p-type MOSFETs, applying a negative voltage to the gate generates drain current. Therefore, by setting the electron beam irradiation energy to electron beam conditions such that the secondary electron yield is less than 1, the gate becomes negatively charged and a negative voltage is applied to the gate. The positive or negative voltage applied to the gate can be controlled by controlling the acceleration voltage of the electron beam injected into the gate, or by placing an electrode directly above the sample and applying an electric field externally. Alternatively, voltage can be applied by direct contact with the terminals of a prober or other device. When using an electron beam to inject electrons into the gate, the electron beam can be irradiated over the entire pattern or a single point within the specified pattern coordinates where the transistor is formed. In addition, an irradiation method may be implemented in which multiple electron beams are used to simultaneously or alternately irradiate negative and positive voltage conditions according to the type of transistor during the same observation, thereby simulating multiple operating states.

[0040] When resetting the charge accumulated in the gate portion, since the gate portion is generally formed on a gate insulating film, the charge is removed by supplying electrons from the substrate material. Therefore, the light control unit 146 removes the charge accumulated in the insulating film by irradiating it with light of wavelength 1 that is absorbed by the substrate material. At this time, the portion formed on the junction structure is also reset at the same time because it is made of the same substrate material. For example, in a typical DRAM (Dynamic Random Access Memory) constructed on a Si substrate with an insulating film and a junction structure, irradiating it with light of a wavelength of 500 nm or less allows the overall accumulated charge of the DRAM structure to be controlled and reset. Furthermore, the amount of charge accumulated in the gate portion can be controlled by controlling the irradiation dose and wavelength. Furthermore, when controlling the charge in the gate portion, light of a wavelength that is directly absorbed by the gate insulating film may be irradiated. Resetting the charge in the gate portion turns off the transistor.

[0041] Wavelength 2 is selected to remove the charge only from the portion formed on the junction, thereby resetting only the charge accumulated in the source and drain portions while leaving the charge stored in the gate portion (while the gate portion remains ON).

[0042] When S104 is performed for the first time, the light control unit 146 can reset the charged state of the gate unit by irradiating it with light of wavelength 1. In the loop of S104 to S106, for example, each time the observation position is moved by one line in the Y direction, the charged states of the source unit and drain unit can be reset by irradiating it with light of wavelength 2. For example, if it is desired to observe characteristics such as a junction's breakdown voltage failure or recovery time, it is sufficient to irradiate it with wavelength 2 and then acquire a detection signal from the detector 114. If it is desired to observe the ON / OFF characteristics of the gate unit (how much applied voltage, i.e., how much injected charge is required to turn it ON) or to reset the entire transistor, it is sufficient to use wavelength 1.

[0043] The secondary signal level detected by detector 114 (i.e., the brightness level of the observed image at that observation position) differs depending on whether the transistor is in the ON state. Therefore, the ON / OFF state of the transistor can be obtained based on the detected signal level or the pixel value of the observed image. The calculation unit 148 can measure the ON / OFF characteristics of the transistor accordingly.

[0044] Figure 5 shows an example of the in-plane distribution created by the calculation unit 148 in S108. By acquiring the detection signal from the detector 114 for each observation position while changing the amount of charge injected into the sample 122, the relationship between the amount of injected charge and the detection signal, as shown in the lower diagram of Figure 5, can be obtained for each observation position on the sample 122. This results in the in-plane distribution shown in the upper diagram of Figure 5. For example, in the black-shaded areas, the detection signal decreases rapidly as the amount of injected charge increases. In contrast, in the shaded areas, the decrease in the detection signal with respect to the increase in the amount of injected charge is gradual. This difference is due to the fact that the characteristics of the transistor's transition between the ON / OFF state when the amount of injected charge (i.e., the voltage applied to the gate) is gradually increased differ for each semiconductor chip formed on the sample 122. The in-plane distribution represents the distribution of these differences in characteristics.

[0045] The in-plane distribution shown in Figure 5 can be obtained without necessarily acquiring an observation image of the sample 122. In other words, if the detection signal level from the detector 114 is acquired for each amount of injected charge, the characteristics shown in the lower diagram of Figure 5 can be obtained, and this can be used to create the in-plane distribution. For example, to obtain the in-plane distribution shown in Figure 5 for only the drain section of a transistor, it is sufficient to acquire the detection signal level when the drain section is irradiated with an observation electron beam. Obtaining the in-plane distribution without generating an observation image ensures measurement throughput. For example, the in-plane distribution shown in Figure 5 can be quickly obtained during the manufacturing process without stopping the process.

[0046] <First embodiment: Summary> The charged particle beam device 1 according to the first embodiment measures the ON / OFF characteristics (gate threshold voltage (Vth) characteristics) relative to the amount of charge injected into a transistor using a wavelength 1 that initializes the charged state of the gate portion of a transistor formed on a sample 122 and a wavelength 2 that initializes only the charged states of the drain portion and source portion. This makes it possible to measure the ON / OFF characteristics of a transistor using light irradiation and charged particle beam irradiation without connecting a measuring device such as an electric probe to the transistor.

[0047] <Embodiment 2> 6 is a diagram illustrating an example of the operation of the charged particle beam device 1 when measuring the parasitic capacitance between the gates of transistors. In FIG. 6, two transistors are connected so that they share a source or a drain (the source terminal is shared in FIG. 6). The charged particle beam device 1 can measure the parasitic capacitance between the gate terminals in FIG. 6 (the portion indicated by the dotted line in FIG. 6) by the following procedure. The configuration of the charged particle beam device 1 is the same as that of the first embodiment.

[0048] The control message unit 147 irradiates the sample 122 with an electron beam so as to turn on only one of the transistor gates. This injects a sufficient amount of charge into the gate portion on the right side of Figure 6, for example, to turn on the transistor. If the parasitic capacitance between the gate terminals is small enough at this time, only the transistor into which the charge was injected will conduct. On the other hand, if the parasitic capacitance is equal to or greater than a certain reference value, charge will also be injected into the other gate via that parasitic capacitance, causing that other transistor to conduct.

[0049] The conduction of a transistor can be detected by the detection signal level when the transistor is irradiated with an observation electron beam. That is, the detection signal from a transistor in a conducting state and the detection signal from a transistor in a non-conducting state have different signal levels. Based on the detection signal level of each transistor in the above procedure, the calculation unit 148 can measure whether the parasitic capacitance, as indicated by the dotted line in Figure 6, is equal to or greater than a reference value.

[0050] FIG. 7 shows an example of the sequence for irradiating electron beams and light to calculate parasitic capacitance. Parasitic capacitance is measured by observing the time constant of the relaxation process of the injected charge. For example, the interval between irradiations of the electron beam is changed, and the electrons emitted at that time are acquired by the detector 114. If the parasitic capacitance of the gate is small, the time constant is small, and the time until the accumulated charge is discharged is shortened. If the parasitic capacitance is large, the time constant is long, and therefore, by acquiring the brightness of the observed image of the gate at each interval between irradiations of the electron beam, it is possible to calculate the parasitic capacitance between gates. The same step numbers are used for steps similar to those in FIG. 3, and the following explanation will mainly focus on the differences from FIG. 3.

[0051] In this flowchart, the parasitic capacitance is calculated by acquiring detection signals while varying the irradiation interval (interval step in the GUI described below) and current amount (irradiation current amount or pulse electron width) of the electron beam irradiated during observation electron irradiation (S106).

[0052] In step S104-1, the potential state of the entire transistor is made uniform, and in step S105, charge is injected into one of the gate portions. The observation position is moved to the drain portion formed by a switch such as a junction, and in step S104-2, only the drain portion formed by the junction structure is reset. According to the conditions set in S102, the parasitic capacitance is calculated by acquiring a detection signal while varying the irradiation interval (interval step in the GUI described below) and current amount (irradiation current amount or pulse electron width) of the electron beam irradiated by observation electron irradiation (S106). At this time, the light set in step S104-2 is irradiated onto the sample 122 every time the conditions such as the irradiation interval change.

[0053] <Embodiment 2: Summary> The charged particle beam device 1 according to the second embodiment measures the parasitic capacitance between wirings to a transistor using a wavelength 1 that initializes the charged state of the gate portion of the transistor formed on the sample 122 and a wavelength 2 that initializes only the charged states of the drain portion and the source portion. This allows the parasitic capacitance between wirings to be measured using light irradiation and charged particle beam irradiation without connecting a measuring device such as an electric probe to the transistor, thereby making it possible to indirectly evaluate the distance between wirings, the quality of the insulating film, and the like.

[0054] <Third Embodiment> 8 is an example of a user interface presented by the calculation unit 148 via the display unit 155. The user interface (GUI) can present, for example, the following: (a) a charged particle beam irradiation condition input section for inputting irradiation conditions for an electron beam (both for observation and for charge injection); (b) a light irradiation condition input section for inputting irradiation conditions for light; (c) an observed image of the sample 122; (d) inspection results for the sample 122 (transistor); and (e) the in-plane distribution of FIG. 5 (at least one of the distribution image in the upper row and the graph in the lower row of FIG. 5).

[0055] The user can view the measurement results on the GUI and also specify and input each irradiation condition. The control message unit 147 controls each unit according to the specified input, thereby carrying out the measurement sequence described in Figures 3 and 4 (or Figure 6).

[0056] <Modifications of the present invention> In the above embodiment, it has been explained that the in-plane distribution shown in Fig. 5 can be generated using the detection signal levels without necessarily generating an observation image of the sample 122. As information used to measure the sample 122, it may be possible to switch between using only the detection signal levels or generating an observation image. For example, it may be possible to allow the user to specify on the GUI whether or not to generate an observation image.

[0057] In the above embodiment, the light irradiation conditions for wavelength 1 and wavelength 2 described in Fig. 4 may be switched based on whether a designated portion of sample 122 absorbs the light, and therefore do not necessarily have to be wavelength-switched. For example, if the light output determines whether the irradiated portion absorbs the light, output switching may be used instead of wavelength switching. Furthermore, these may be combined.

[0058] In the above embodiment, the control message unit 147 and the calculation unit 148 have been described as separate functional units, but they may be configured as an integrated control unit. The control system 14 and the operation system 15 (and the respective functional units they comprise) may be configured by hardware such as a circuit device that implements these functions, or by a calculation device such as a CPU (Central Processing Unit) that executes software that implements these functions.

[0059] In the above embodiments, we have described injecting charge into a sample or obtaining an observation image of the sample by irradiating it with an electron beam, but the present invention can also be applied to cases where similar functions are achieved by irradiating it with other charged particle beams. [Explanation of symbols]

[0060] 1: Charged particle beam equipment 11: Electron optical system 114: Detector 13:Light irradiation system 147: Control and Communication Department 148: Arithmetic section

Claims

1. A charged particle beam device that irradiates a sample with a charged particle beam, a charged particle beam irradiation unit that irradiates the sample with the charged particle beam; a light irradiation unit that irradiates the sample with light; a detector that detects secondary particles generated from the sample by irradiating the sample with the charged particle beam and outputs a detection signal representing the intensity of the secondary particles; a calculation unit that processes the detection signal; Equipped with the sample is a transistor formed on a semiconductor material; the charged particle beam irradiation unit irradiates the gate of the transistor with the charged particle beam to inject charges, thereby turning on the transistor; the light irradiating unit irradiates the transistor with the light to initialize charges held by the transistor, thereby controlling the conduction state of the transistor; The calculation unit measures the ON / OFF characteristics of the transistor with respect to the amount of charge injected into the transistor, using the detection signal obtained in the process of controlling the conduction state of the transistor. A charged particle beam device characterized by:

2. the light irradiation unit irradiates the transistor with light having a first wavelength that is absorbed by the semiconductor material or a gate insulating layer formed on the semiconductor material, thereby initializing charges held by the gate; The light irradiation unit initializes the charge held by the gate to turn off the transistor.

2. The charged particle beam device according to claim 1.

3. The light irradiation unit irradiates the transistor with light having a second wavelength that is not absorbed by a gate insulating layer formed on the semiconductor material but is absorbed by the semiconductor material, thereby initializing charges held in the source and drain of the transistor while keeping the gate turned on.

2. The charged particle beam device according to claim 1.

4. the light irradiation unit repeatedly changes the irradiation amount of the charged particle beam so that the amount of charge injected into the transistor changes after the charge in the gate is initialized; The calculation unit acquires the detection signal for each repetition, thereby measuring the ON / OFF characteristics of the transistor for each amount of charge injected into the transistor.

3. The charged particle beam device according to claim 2.

5. The calculation unit measures an in-plane distribution of the ON / OFF characteristics of the transistor on the surface by performing the measurement for each position on the surface of the semiconductor material.

5. The charged particle beam device according to claim 4.

6. the transistors are configured across multiple lines on the semiconductor material; the light irradiation unit irradiates the transistor with light having a second wavelength that is not absorbed by a gate insulating layer formed on the semiconductor material but is absorbed by the semiconductor material, thereby initializing charges in the source and drain of the transistor while keeping the gate ON; the calculation unit scans a position where the detection signal is acquired along an extension direction of a first line in which the transistors are arranged; After the light irradiation unit has finished acquiring the detection signal for the first line, and before the calculation unit starts acquiring the detection signal along an extension direction of a second line adjacent to the first line, the light irradiation unit performs the initialization, thereby initializing charges held by the source and the drain of the transistor arranged along the second line.

5. The charged particle beam device according to claim 4.

7. the transistor includes a first transistor and a second transistor that share a source or a drain; the charged particle beam irradiation unit performs a parasitic capacitance evaluation sequence in which the gate of the first transistor is turned on but the gate of the second transistor is not turned on by irradiating the charged particle beam onto the gate of the first transistor but not onto the gate of the second transistor; The calculation unit measures the parasitic capacitance between the gate of the first transistor and the gate of the second transistor by evaluating whether the second transistor is conductive or not when the parasitic capacitance evaluation sequence is performed.

2. The charged particle beam device according to claim 1.

8. the calculation unit generates an observation image of the transistor using the detection signal obtained in a process of controlling the conduction state of the transistor; The calculation unit measures the ON / OFF characteristics of the transistor based on the luminance value of the image of the transistor on the observation image.

2. The charged particle beam device according to claim 1.

9. The light irradiation unit a first light source that emits the light having a first wavelength, and a second light source that emits the light having a second wavelength; a light source that emits the light, and a wavelength converter that converts the wavelength of the light; a light source capable of emitting both the light having the first wavelength and the light having the second wavelength; a light source that emits the light having a plurality of wavelength components, and a wavelength filter that selects one of the wavelength components; It is composed of at least one of the following:

2. The charged particle beam device according to claim 1.

10. the computing unit provides a user interface; The user interface includes: a charged particle beam irradiation condition input unit for inputting irradiation conditions of the charged particle beam; a light irradiation condition input unit for inputting the light irradiation conditions; an observed image of the sample; As a result of inspecting the transistor, Present at least one of the following:

2. The charged particle beam device according to claim 1.

11. The calculation unit provides a user interface that presents the in-plane distribution.

6. The charged particle beam device according to claim 5.

12. A method for measuring a sample by irradiating the sample with a charged particle beam, comprising: irradiating the sample with the charged particle beam; irradiating the sample with light; a step of detecting secondary particles generated from the sample by irradiating the sample with the charged particle beam and outputting a detection signal representing the intensity of the secondary particles; processing the detection signal; and the sample is a transistor formed on a semiconductor material; In the step of irradiating a charged particle beam, the charged particle beam is irradiated onto a gate of the transistor to inject charges, thereby turning on the transistor; In the step of irradiating light, the transistor is irradiated with light to initialize charges held by the transistor, thereby controlling the conduction state of the transistor; In the step of processing the detection signal, the detection signal obtained in the process of controlling the conduction state of the transistor is used to measure the ON / OFF characteristics of the transistor with respect to the amount of charge injected into the transistor. A measuring method characterized by:

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