Inspection device and membrane inspection method

Abstract

The film quality of a semiconductor film or insulating film formed on a sample (16) is inspected non-contactually. The inspection device (1) for inspecting the film quality of a film formed on a sample (16) comprises a charged particle source (12) that irradiates a charged particle beam (13) onto the sample, a first light source (21) that irradiates a first light (26) onto the sample, a light detector that detects a signal light (28) generated by the first light being irradiated onto the sample, a charge control electrode (17) that controls the electric field on the sample or a second light source (22) that irradiates a second light (27) onto the sample, a control device (30) that modulates the electronic state of the sample using the charged particle source, the charge control electrode, or the second light source, and a calculator (31) that estimates the film quality of a film formed on the sample based on a detection signal of the signal light modulated according to the modulation of the electronic state of the sample output from the light detector.

Description

Technology Field

[0001] The present disclosure relates to an inspection device and a method for inspecting film quality using the same. Background Technology

[0002] Patent Document 1 describes an SEM equipped with ultraviolet light for static elimination. It is known that the charge on an insulating film can be removed by irradiation with ultraviolet light. Patent Document 2 describes an SEM equipped with a charge control electrode that controls the electric field on a sample. It is known that the amount of charge on a sample charged by electron beam irradiation can be controlled by controlling the voltage of the charge control electrode. Prior art literature

[0003] Japanese Patent Publication No. 2000-357483 Japanese Patent Publication No. 2006-338881

[0004] DE Aspnes, "Third-Derivative Modulation Spectroscopy with Low-Field Electroreflectance" Surface Science 37 (1973) 418-442 The problem to be solved

[0005] In semiconductor devices, the quality of the semiconductor film or insulating film is important. For example, the performance of a transistor is largely determined by the properties of the gate insulating film or the properties of the interface between the gate insulating film and the layer in contact with it. If defects exist in the insulating film or the interface, charges accumulate in the defects due to the application of an electric field during device operation, which adversely affects device operation. For inspecting film quality issues that become problematic during device operation, such as these defects, it is effective to apply an electric field to the film under inspection just as it is during device operation and measure the change in its characteristics.

[0006] After the device is completed, the film quality can be inspected by electrical characteristic testing during actual operation. However, inspection after completion cannot prevent problems from occurring during the mass production process. Furthermore, in the development of semiconductor manufacturing processes, it becomes possible to measure film quality under an applied electric field by fabricating electrodes that insert the film to be inspected and applying voltage between the electrodes; however, fabricating such electrodes requires time and cost.

[0007] Therefore, in the mass production process of semiconductor devices or in the development of semiconductor manufacturing processes, it is desired to inspect the film quality, such as deposited semiconductor films or insulating films, non-contactually. Here, film quality refers to the material characteristics exhibited by the film according to the charge, deformation, defects, or the condition of the substrate or interface contained in the deposited material. Furthermore, the films subject to inspection in the present invention broadly include films formed during the manufacturing process of semiconductor devices, regardless of the film's manufacturing method or material. For example, films subject to processing such as annealing after deposition, films obtained by thermal oxidation of a semiconductor substrate (thermal oxide films), and films formed by ion implantation into a semiconductor substrate are also subject to inspection. Additionally, both inorganic and organic materials are included. means of solving the problem

[0008] An inspection device of one aspect of the present invention is an inspection device for inspecting the film quality of a film formed on a sample, and comprises a charged particle source for irradiating a charged particle beam onto a sample, a first light source for irradiating a first light onto a sample, a light detector for detecting a signal light generated by the irradiation of the first light onto the sample, a charge control electrode for controlling an electric field on the sample or a second light source for irradiating a second light onto the sample, a control device for modulating the electronic state of the sample using the charged particle source, the charge control electrode or the second light source, and a calculator for estimating the film quality of a film formed on a sample based on a detection signal of a signal light sampled in synchronization with the modulation of the electronic state of the sample output from the light detector.

[0009] A film quality inspection method according to one aspect of the present invention is a film quality inspection method for inspecting the film quality of a film formed on a sample, wherein a charged particle beam is irradiated onto a sample to charge the sample, a probe light is irradiated onto the sample while the electronic state of the sample is modulated, a signal light generated by the irradiation of the probe light onto the sample is detected, and the film quality of the film formed on the sample is estimated based on the detection signal of the signal light sampled in synchronization with the modulation of the electronic state of the sample. Effects of the invention

[0010] It becomes possible to inspect film materials, such as deposited semiconductors or insulating films, non-contactually. Other problems and novel features will become apparent from the description in this specification and the accompanying drawings. Brief explanation of the drawing

[0011] Figure 1 is a schematic diagram of the inspection device of Example 1. Figure 2a is an example of a control sequence that controls the electronic state of a sample. Figure 2b is an example of a control sequence that controls the electronic state of a sample. Figure 2c is an example of a control sequence that controls the electronic state of a sample. Figure 3a is an example of a detection signal spectrum. Figure 3b is an example of a detection signal spectrum. Figure 4 is an example of a data structure of a database for estimating membrane quality. Figure 5 is a control flow for film quality inspection that can be estimated from the electric field dependence of the detection signal. Figure 6 is a diagram illustrating the change in the intensity of the detection signal when the applied voltage of the charge control electrode is extinguished. Figure 7 is an example of a data structure of a database for estimating film quality obtained from the electric field dependence of a detection signal. Figure 8 is an example of the display of the results of the membrane quality test. Figure 9a is an example of a setting and measurement screen (setting tab). Figure 9b is an example of a settings and measurement screen (measurement tab). Figure 9c is an example of a result output screen. FIG. 10a is a schematic diagram of the inspection device of Variant Example 1. Figure 10b is a diagram illustrating the relationship between the signal electron detection amount and the energy filter voltage. FIG. 11 is a schematic diagram of the inspection device of Variant Example 2. FIG. 12 is a schematic diagram of the inspection device of Example 2. FIG. 13 is a schematic diagram of the inspection device of Example 3. FIG. 14 is a schematic diagram of the inspection device of Example 4. Specific details for implementing the invention

[0012] Embodiments of the present invention will be described below. Furthermore, while the drawings shown in these embodiments illustrate specific examples of the present invention, they are intended for understanding the invention and are by no means intended to limit the interpretation of the invention.

[0013] In the inspection device of the present embodiment, the film quality is evaluated by optical inspection. That is, although specific examples will be described later, the material properties of the film are detected as optical properties of the film, and information regarding the film quality is obtained from the detected optical properties. In the present embodiment, during optical inspection, the electronic state of the sample to be inspected is modulated and controlled by controlling the charge of the film to be inspected and / or by controlling the internal electric field through light irradiation.

[0014] In the following embodiments, the purpose of controlling the electric field strength on the film to be inspected is broadly divided into two categories. The first is to optimize the conditions for optical inspection. For example, by performing optical inspection under an electric field strength at which maximum signal light intensity is obtained, inspection with high SNR can be performed, thereby improving the inspection throughput. The second is to inspect the electric field-dependent film properties. Regarding material properties dependent on electric field strength, information about the film properties can be obtained by detecting changes in the detection signal by varying the applied electric field strength. Details will be described later.

[0015] In the following, examples are disclosed in which the subject of inspection is an insulating film deposited on a semiconductor wafer and its interface, but the application of the present technology is not limited thereto. Film quality measurement under an electric field is effective, for example, for semiconductor films, organic films, and their interfaces.

[0016] Examples 1

[0017] FIG. 1 illustrates the schematic configuration of the inspection device (1) of Example 1. The inspection device (1) has, as its main components, a charged particle beam device for controlling the electronic state of the sample to be inspected in the sample, a light irradiation system for irradiating the sample with probe light, a light detection system for detecting signal light generated by irradiating the sample with probe light, and a control system for controlling these.

[0018] (Charged particle beam device)

[0019] The charged particle beam device is equipped with a sample chamber (10) and a barrel (11), and the interior of these is maintained in a vacuum atmosphere by an exhaust mechanism not shown. A sample (16), such as a semiconductor wafer, is contained in the sample chamber (10). A charged particle source (12) that generates a charged particle beam (13) to be irradiated onto the sample (16), and a blanker (14) that chops the charged particle source (12) are contained in the barrel (11). Here, as the charged particle source (12), it is sufficient to be able to generate a charged particle beam (13) to charge the sample (16), and an electron gun, a flood gun, an ion source, etc., may be used. Additionally, a charged particle optical component, such as a lens or a deflector, which constitutes a charged particle optical system for guiding the charged particle beam (13) to the sample (16) may be provided.

[0020] In the vicinity of the sample (16), a charge control electrode (17) is provided to control the charge amount of the sample (16) by controlling the electric field on the sample (16). By applying voltage to the charge control electrode (17), the electric field directly above the sample (16) is controlled. The electric field applied to the charge control electrode (17) controls the charge state of the sample (16) by causing secondary charged particles generated when a charged particle beam (13) is irradiated onto the sample (16) to move away from the sample (16) or return to it. The charge control electrode (17) is positioned at a distance of, for example, several to 30 mm from the sample (16). For this reason, it is preferable to construct it using a metal mesh or a perforated electrode plate so as not to become an obstacle to irradiating the charged particle beam (13), or the probe light (26) or pump light (27) described later onto the sample (16).

[0021] In addition, the charge of the sample (16) can be quickly removed by using ultraviolet light as disclosed in Patent Document 1. Meanwhile, it is known that in the case of light with a longer wavelength than ultraviolet light, the electric field (interface electric field) inside the sample can be controlled without changing the charge state. For this reason, in the configuration example of FIG. 1, a second light source (22) is provided to irradiate light (referred to as pump light (second light) (27)) onto the sample (16). By irradiating the pump light (27), the electronic state of the sample to be inspected can be controlled, and by selecting the wavelength of the pump light (27), the content of the electronic state being controlled can be changed. Specifically, by using ultraviolet light, the charge of the sample can be removed and the interface electric field can be controlled, and by using light with a longer wavelength than ultraviolet light, the interface electric field can be controlled. The second light source (22) can be configured in the same way as the first light source (21) described later.

[0022] (Light irradiation system)

[0023] The inspection device (1) is equipped with a first light source (21) that irradiates probe light (first light) (26) onto a sample (16) to perform an optical inspection of a film to be inspected formed on a sample (16). As the first light source (21), a white light source such as a xenon lamp, a laser, an LED, etc., may be used. A white light source may also be used by monochromating it through a monochromator. Additionally, although not shown, the light irradiation system is equipped with optical components such as a lens or mirror that constitute an optical system for guiding the probe light (26) to the sample (16), and a polarizer that controls the polarization of the probe light (26).

[0024] In the example of FIG. 1, the first light source (21) is positioned outside the sample chamber (10), and the probe light (26) is introduced into the sample chamber (10) through a viewport (15a) provided in the sample chamber (10). In this example, the pump light (27) is also introduced into the sample chamber (10) through the viewport (15a), but the probe light (26) and the pump light (27) may be introduced into the sample chamber (10) from different viewports.

[0025] (Optical detector)

[0026] By irradiating the sample (16) with probe light (26), signal light (28) is generated. The signal light (28) includes reflected light, scattered light (including Raman scattered light), luminescence, and diffracted light. The light detection system detects the signal light (28) and is equipped with an optical filter (23), a light detection system (24), and a signal processing device (25). The optical filter (23) is a filter that removes light other than the signal light (28), and the light detection system (24) detects the signal light (28) by receiving light that has passed through the viewport (15b) through the optical filter (23). As the light detection system (24), a power meter, a photodiode, a spectrometer, etc., may be used in accordance with the signal light (28) being detected. The signal processing device (25) processes the detection signal of the light detection system obtained under electric field conditions inside a plurality of samples. The signal processing device (25) is, for example, a lock-in amplifier and extracts the modulation strength or phase of the detection signal from the light detection system (24).

[0027] The signal light (28) detected by the light detection system (24) is determined according to the film material being inspected on the film to be inspected. For example, information such as interfacial electric field, defects, and deformation can be obtained by detecting reflected light; information such as vibration level, stress, and deformation can be obtained by detecting scattered light (including Raman scattered light); information such as defects and luminous efficiency can be obtained by detecting luminescence; and information such as structural periodicity and refractive index can be obtained by detecting diffracted light.

[0028] (Control system)

[0029] The control device (30) controls the components of the inspection device (1). The control device (30) controls the operation of the charged particle beam device, the light irradiation system, and the light detection system based on inspection conditions input from, for example, a calculator (31). The control device (30) is realized by a program executed on a processor, for example, a CPU. In addition, it may be configured with, for example, a Field-Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC).

[0030] The setting of conditions for inspection and measurement by the inspection device (1) or the estimation of film quality based on the detection signal from the optical detector is performed by the calculator (31). The calculator (31) stores various databases or conversion formulas necessary for setting conditions or estimating film quality.

[0031] The setting of conditions for inspection and measurement includes the setting of parameters as follows. These parameters are set by the user through the GUI of the calculator (31). Conditions for the charged particle beam (13) that charges the sample include acceleration voltage, current amount, irradiation area, irradiation position, and irradiation period by the blanker. Conditions for the charge control electrode (17) that controls the charge amount of the sample include the voltage value and the application period. Conditions for the pump light (27) that controls the static discharge or internal electric field of the sample include wavelength, intensity, polarization, and irradiation period. Conditions for the probe light (26) include wavelength, intensity, and polarization. Conditions for the detector of the light detection system (24) include gain.

[0032] In addition, it is also possible to configure the calculator (31) to perform the function of the control device (30).

[0033] FIGS. 2a to 2c illustrate examples of control sequences for modulating the electronic state of a sample. Each example is a control sequence in which the electronic state of a sample (16) is controlled by three operating sources: a charged particle beam (13), a charge control electrode (17), and a pump light (27). FIG. 2a fixes the conditions of the charged particle beam (13) and the charge control electrode (17) and modulates the conditions of the pump light (27). The modulation parameter may be wavelength or polarization, but here it is set to intensity. When the intensity of the pump light (27) is ON, the charge of the sample (16) is removed or the electric field inside the sample is controlled depending on the wavelength of the pump light (27). FIG. 2b fixes the conditions of the charged particle beam (13) and the pump light (27) and modulates the conditions of the charge control electrode (17). FIG. 2c fixes the conditions of the charge control electrode (17) and the pump light (27) and modulates the conditions of the charged particle beam (13). In order for the electronic state of the sample (16) to be modulated, any parameter may be modulated for at least one of the three working sources. When modulating multiple working sources, the modulation patterns of the multiple working sources may be the same or different. In addition, if the wavelength of the pump light (27) is short-wavelength and used for the purpose of static discharge of the inspection target film, and it is sufficient to control only the presence or absence of charge of the sample, the charge control electrode (17) may be omitted. Furthermore, as in the control sequence of FIG. 2b and FIG. 2c, when modulating the amount of charge of the sample by the charged particle beam (13) and the charge control electrode (17), the second light source (22) may be omitted. However, even in such cases, if you want to control the electric field (interface electric field) inside the sample, it is effective to provide a second light source (22) capable of irradiating light with a longer wavelength than ultraviolet light, and if you want to reset the charge amount of the sample every modulation, it is effective to provide a second light source (22) capable of irradiating ultraviolet light.

[0034] Sampling of the detection signal output by the optical detector system detecting the signal light (28) is performed according to a sampling trigger. The sampling trigger is synchronized with the modulation of the electronic state of the sample. Accordingly, the intensity S of the signal light (28) when the modulating agent is in a first state (in the example of FIG. 2a, the intensity of the pump light (27) is OFF) A and the intensity S of the signal light (28) when the modulating agent is in the second state (in the example of FIG. 2a, the intensity of the pump light (27) is ON). B You can obtain, and strength S A and intensity S B By comparing, information regarding the film quality of the film to be inspected is obtained. The control sequences of FIGS. 2a to 2c all create two types of electronic states, a first state and a second state, but three or more types of electronic states may be created by modulating multiple working sources with different modulation patterns.

[0035] Here, the sampling trigger may have various forms depending on the configuration of the light detection system and is not limited to a specific form. For example, the second light source (22) modulates the pump light (27) in synchronization with the synchronization signal from the control device (30), and the light detection system continuously outputs a detection signal from the signal processing device (25). In this case, the calculator (31) receives the synchronization signal from the control device (30) and can sample the detection signal from the signal processing device (25) by means of a sampling trigger synchronized with the synchronization signal. Alternatively, in the light detection system, the light detection system (24) may continuously output a detection signal, and the signal processing device (25) may be configured to receive the synchronization signal from the control device (30) and perform signal processing by sampling the detection signal from the light detection system (24) by means of a sampling trigger synchronized with the synchronization signal. Additionally, in the light detection system, the light detection system (24) may be configured to receive a synchronization signal from the control device (30) and to detect signal light (28) by a sampling trigger that is synchronized with the synchronization signal. If the detector of the light detection system (24) is a spectrometer, this configuration may be used.

[0036] The signal processing of the signal processing device (25) in the light detection system is described. For example, the detector in the light detection system (24) is set to a power meter, and the signal light (28) is set to be the reflected light of the probe light (26). By applying the control sequence of FIG. 2a, the signal intensity S of the signal light (28) in the first state A , signal intensity S of the signal light (28) in the second state B The signal processing device (25) normalizes the difference in signal strength obtained from two electronic states and outputs it as a detection signal. In this case, the detection signal is expressed as (Equation 1) and represents the rate of change of reflectance.

[0037]

[0038] When a lock-in amplifier is used as the signal processing device (25), an amplitude ΔR0 and a phase θ are output, and in this case, the detection signal is expressed as (Equation 2).

[0039]

[0040] When the detection signal ΔR / R is detected while changing the wavelength of the probe light (26), a spectrum such as that shown in FIG. 3a or FIG. 3b is obtained. The horizontal axis represents the wavelength or energy of the reflected light. Here, FIG. 3a is the case where the voltage of the charge control electrode (17) is set to 0V, and FIG. 3b is the case where the voltage of the charge control electrode (17) is set to +3V. By adjusting the voltage of the charge control electrode (17), that is, the amount of charge of the sample (16), a detection signal with a higher SNR is obtained. In addition, it is possible to obtain the same spectrum by using a white light source for the probe light (26) and a spectrometer as the detector of the light detection system (24).

[0041] The calculator (31) estimates the deformation of the semiconductor or the dopant concentration at the interface between the film, for example, an insulating film and the semiconductor, from the intensity or shape of the detection signal spectrum as shown in FIG. 3a or FIG. 3b. The obtained detection signal spectrum has a relationship expressed, for example, by (Equation 3) (Non-patent Literature 1).

[0042]

[0043] In (Equation 3), A is intensity, θ is phase, E is energy, E CP ε is the critical point energy, Γ is the broadening factor, and n is a coefficient dependent on the material of the film under inspection. Equation 3 is applied to the obtained detection signal spectrum. By fitting, the fitting parameters (A, θ, E) included in Equation 3 are CP, Γ) is obtained. Meanwhile, the calculator (31) holds membrane quality information for various combinations of fit parameters as a database. An example of the database is illustrated in FIG. 4.

[0044] FIG. 4 is an example of a data structure of a database (41) for estimating membrane quality. In the database (41), fit parameters (A, θ, E) CP The strain of the film for a combination of , Γ) is registered. The calculator (31) estimates the strain of the film to be inspected by comparing the fit parameter obtained from (Equation 3) with the database (41). Additionally, the database (41) may register film quality information as a function with the fit parameter as an argument, and is not limited to the registered form. Furthermore, this example is an example in which a model formula and database (41) such as (Equation 3) are used when measuring the strain as the signal light (28) is reflected light of the probe light (26). For example, if the signal light (28) is scattered light or luminescence, or if the measurement target is something other than the strain, a model formula or database corresponding to that may be used.

[0045] The calculator (31) stores the relationship between the parameters obtained from the detection signal and the film quality as a database, and estimates film quality information from the parameters detected from the signal light (28). The calculator (31) has a database based on the detection signal from the light detector used for the film quality inspection performed by the inspection device (1) and an analysis formula, and estimates the film quality using the database based on the inspection performed.

[0046] Next, a control flow is described for the case where the film quality is determined from the electric field dependence of the detection signal. Film quality, such as defects or the amount of moving charge, can be estimated from how the detection signal changes when the electric field applied to the sample is varied (electric field dependence of the detection signal). A control flow for inspecting film quality that can be estimated from such electric field dependence of the detection signal is illustrated in FIG. 5. The case of estimating the amount of moving charge of the film under inspection by applying the control sequence of FIG. 2a is explained as an example.

[0047] First, a variable parameter is selected and its range is set (S01). Here, the variable parameter is set to the applied voltage of the charge control electrode (17). Next, a control sequence for measuring film quality is set. As described above, the control sequence of FIG. 2a is set (S02). The control sequence is executed and the signal light (28) is measured while changing the variable parameter (S03 to S06), and after obtaining a detection signal for the set range of the variable parameter, a feature quantity indicating the variable parameter dependency of the detection signal is calculated (S07). The calculator (31) holds film quality information regarding the feature quantity indicating the variable parameter dependency of the detection signal as a database. By referring to this database, the film quality of the film to be inspected is estimated (S08).

[0048] As an example of a control flow, FIG. 6 shows the change in intensity of the detection signal (ΔR / R) when the applied voltage of the charge control electrode (17) is swept in the forward direction (from minus to plus) and the reverse direction (from plus to minus). The horizontal axis represents the surface potential V of the sample (16). s is. Surface potential V s is the applied voltage V of the charge control electrode (17). cc Since it has the relationship shown in (Equation 4), the applied voltage V cc It can be obtained by converting from. (Mathematical Equation 4) is obtained through simulation, etc.

[0049]

[0050] FIG. 7 is an example of a data structure of a database (51) for estimating film quality obtained from the electric field dependency of a detection signal. In the database (51), the operating charge of the film for combinations of feature quantities (V1, V2, ΔV) representing the electric field strength dependency of the detection signal is registered. The calculator (31) estimates the operating charge of the film to be inspected by comparing the database (51) with the feature quantities representing the electric field strength dependency obtained from measurement results such as FIG. 6 (here, voltages V1, V2, or hysteresis that become a specific reflectance). In addition, by using a database corresponding to the film quality to be targeted, film quality such as fixed charge quantity, flat band voltage, charge contained in the material as described above, deformation, defects, and interface state can be estimated. In addition, the database (51) may register film quality information as a function with feature quantities as arguments, and is not limited to such registration forms.

[0051] FIG. 8 illustrates an example of displaying the results of an optical inspection by an inspection device (1). The optical inspection is performed, for example, on a chip section designated by a user on a semiconductor wafer. The optical inspection may also be performed on the entire chip section. The film quality of each chip section that has undergone optical inspection is displayed as a wafer heatmap (60). In the wafer heatmap (60), chip sections (62) within the wafer (61) are displayed, and, for example, if the inspected film quality is defective, the chip section with a higher defect density is displayed in a darker color. This makes the film quality of each chip section visible to the user.

[0052] Figure 9a illustrates an example of a setting and measurement screen (70), which is a GUI (Graphical User Interface) for performing film quality measurement by an inspection device (1) and displaying the results. The setting and measurement screen (70) is provided with a setting file selection section (71), and a setting file stored in the calculator (31) from a past measurement can be called. For example, when performing inspection of different film quality on the same wafer, the user's workload can be reduced by utilizing past setting contents.

[0053] By selecting the control sequence tab included in the setting tab (72), the control sequence of FIGS. 2a to 2c or other control sequences can be selected. Here, the laser modulation tab (73) is selected, and in this case, as shown in the sequence diagram (74), a control sequence that modulates the pump light shown in FIG. 2a is selected. In addition, in this device, an electron beam is used as the charged particle beam and a laser light is used as the pump light.

[0054] The user opens the laser modulation tab (73) and sets conditions for modulating the electronic state of the wafer in the electron beam condition setting section (75), the charge control electrode condition setting section (76), and the laser condition setting section (77). In addition, in this example, in order to estimate the film quality from the electric field dependence of the detection signal, the applied voltage is set to be erased in the charge control electrode condition setting section (76). In this case, the erase range setting section (78) is displayed, and the user sets the range for erasing the applied voltage. When the above settings are finished, the user presses the save button (79) to save the settings.

[0055] When the condition setting is finished, the user opens the measurement tab (81) as shown in FIG. 9b. The user specifies the chip section to be optically inspected in the inspection chip section setting section (82) and presses the inspection execution button (83). Accordingly, an optical inspection is performed on the specified chip section under the conditions set in the setting tab (72). When the optical inspection for the entire specified chip section is finished, a wafer heatmap is displayed on the wafer heatmap display section (84) to briefly show the inspection results to the user. The user checks the inspection results and presses the save button (85) to save the results of the optical inspection.

[0056] The user can check the details of the inspection results from the result output screen (90) illustrated in FIG. 9c. From the result file selection unit (91) provided on the result output screen (90), the result data file displayed in detail is called. In this example, a wafer heatmap display unit (92) and a histogram display unit (93) are provided, which display the same wafer heatmap as the setting / measurement screen (70). The histogram displayed on the histogram display unit (93) indicates the frequency of occurrence of shades (number of chip sections) representing the defect density in the wafer heatmap displayed on the wafer heatmap display unit (92). Additionally, by specifying any of the chip sections displayed on the wafer heatmap display unit (92), the details of the measurement results in an individual chip section can be displayed. In this example, the inspection chip section measurement result display unit (94) displays the measurement result of the detection signal in a specific chip section or estimated film quality information.

[0057] (Variation Example 1)

[0058] FIG. 10a illustrates a modified example of the inspection device (1) shown in FIG. 1. In Example 1, when the applied voltage of the charge control electrode (17) is extinguished, the sample surface potential V s Using (Equation 4), the applied voltage V of the charge control electrode (17) ccIt was explained that the conversion from (Equation 4) is obtained through simulation, etc. However, depending on the measurement conditions, the value obtained from (Equation 4) and the true sample surface potential V s There is a risk of error occurring between them.

[0059] The inspection device (1b) of FIG. 10a is the sample surface potential V of the sample (16). s As a device for measuring, an energy filter (101) and a signal electron detector (102) are provided. Here, the signal electron detector (102) is a detector that detects signal electrons (100) generated when a charged particle beam (13) is irradiated onto a sample (16), and the signal electrons (100) to be detected may be secondary electrons or reflected electrons (backscattered electrons). A negative voltage is applied to the energy filter (101) by a control device (30), and only signal electrons capable of crossing the electric field barrier generated by the negative voltage are detected by the signal electron detector (102). That is, the amount of signal electrons detected by the signal electron detector (102) depends on the voltage of the energy filter (101). Using this feature, in the inspection device (1b), the calculator (31) obtains the sample surface potential V from the energy of the signal electrons (100). s Calculates.

[0060] FIG. 10b illustrates the relationship between the signal electron detection amount and the energy filter voltage. A signal electron spectrum can be acquired by detecting the signal electron detection amount while varying the negative voltage applied to the energy filter (101). The shift amount is the sample surface potential V s It depends on the sample surface potential V. sThis is because the force that returns the signal electrons (100) to the sample side changes. If the signal electron spectrum (103) is the signal electron spectrum when the sample (16) is uncharged, then the signal electron spectra (104, 105) are the signal electron spectra when the sample (16) is positively charged and negatively charged, respectively. Therefore, for example, the voltage at which the derivative value of the signal electron spectrum is maximum is the sample surface potential V s If defined as such, the potentials for non-charged, positively charged, and negatively charged states become potentials V0, V1, and V2, respectively. Accordingly, without using the conversion formula in (Equation 4), the sample surface potential V s It can be measured. In addition, the signal electronic spectrum (103) can be obtained by measuring the sample (16) after removing the charge using a short-wavelength pump light (27), such as ultraviolet light.

[0061] In this modified example, the energy of the signal electron (100) is differentiated using an energy filter (101), but the electron energy is also detected by a spectrometer or the like that spectrally detects the signal electron according to its energy, thereby allowing the sample surface potential V to be detected. s It is possible to measure.

[0062] (Variation Example 2)

[0063] FIG. 11 illustrates a modified example of the inspection device (1) shown in FIG. 1. Modified Example 2 is similar to Modified Example 1 in that the sample surface potential V s It makes it possible to measure the actual surface potential V of the sample (16). The inspection device (1c) measures the sample surface potential V of the sample (16). s As a device for measuring, a surface potential meter (110) is provided. By moving the sample (16) to the position of the surface potential meter (110) provided in the sample chamber (10), the sample surface potential V s Measures.

[0064] Hereinafter, other configuration examples of the inspection device (1) are described as Examples 2 to 4. Configurations identical to those in Example 1 are given the same reference numerals, and redundant descriptions are omitted.

[0065] Examples 2

[0066] In Example 1, the sample (16) is placed in a vacuum atmosphere, and since vacuum evacuation takes time, the throughput of the inspection measurement is reduced. Example 2 is a configuration example in which the sample (16) is placed in the atmosphere.

[0067] In the configuration of the inspection device (2) illustrated in FIG. 12, the charged particle source (12) is placed inside a tube (11) that is in a vacuum atmosphere, and the tube (11) is provided with a partition (120) to maintain the interior in a vacuum atmosphere. The charged particle beam (13) emitted from the charged particle source (12) penetrates the partition (120) and is emitted into the atmosphere, and is irradiated onto the sample (16). Additionally, if the charged particle source (12) is an electrode that generates ions by corona discharge in the atmosphere, the tube (11) and the partition (120) for maintaining the charged particle source in a vacuum atmosphere may also be unnecessary.

[0068] Examples 3

[0069] In Example 3, photoelectrons generated by irradiating a metal electrode with excitation light are used as charged particles. The inspection device (3) of Example 3 uses an electron source with a simple configuration as a charged particle source, and can modulate the amount of charge of the sample (16) by the exchange of photoelectrons generated by irradiating the sample (16) and / or the charge control electrode (17) with short-wavelength light.

[0070] The third light source (131) and the fourth light source (132) are light sources that generate light with a wavelength of less than 400 nm, and their output is controlled by a control device (30). The third light source (131) and the fourth light source (132) can each be configured in the same way as the first light source (21). The third light source (131) and the fourth light source (132) are placed outside the sample chamber (10), and light from these light sources is introduced into the sample chamber (10) through a viewport (15c) provided in the sample chamber (10).

[0071] The first excitation light (third light) (133) from the third light source (131) is irradiated onto the charge control electrode (17). A first photoelectron (135) is generated from the location where the first excitation light (133) is irradiated. If the potential of the charge control electrode (17) is negative compared to the sample (16), the first photoelectron (135) receives a force in the direction of the sample and is irradiated onto the sample (16). Consequently, the sample (16) becomes negatively charged.

[0072] Meanwhile, the second excitation light (fourth light) (134) from the fourth light source (132) is irradiated onto the sample (16). A second photoelectron (136) is generated from the location where the second excitation light (134) is irradiated. If the potential of the charge control electrode (17) is positive compared to the sample (16), the second photoelectron (136) receives a force in the direction of the charge control electrode and moves away from the sample (16). Consequently, the sample (16) becomes positively charged.

[0073] In this way, the potential of the sample (16) can be modulated and controlled by the first photoelectron (135) and the second photoelectron (136) originating from the first excitation light (133) and the second excitation light (134). The third light source (131) and the fourth light source (132) may be combined into a single light source, in which case the light path of the excitation light is controlled by the control device (30) so that the excitation light is irradiated onto the charge control electrode (17) or the sample (16). Alternatively, the configuration may be such that the excitation light is irradiated simultaneously onto both the charge control electrode (17) and the sample (16). Furthermore, to avoid absorption of the short-wavelength light in the atmosphere, the third light source and the fourth light source may be placed in a vacuum.

[0074] Examples 4

[0075] In the configuration of the inspection device (1) shown in FIG. 1, the arrangement of the charge control electrode (17) and the charged particle source (12) interferes with the probe light (first light) (26) or the pump light (second light) (27), so the light irradiation system and the light detection system cannot be placed near the sample (16). Because of this, it is difficult to concentrate light onto the sample, and there is a limit to the spatial resolution of the measurement. In the inspection device (4) of Example 4, in order to obtain high spatial resolution, an optical system such as an objective lens for the probe light and signal light is placed directly above the sample.

[0076] In the inspection device (4), an optical lens (141) for irradiating probe light (26) and pump light (27) onto a sample (16) is positioned directly above the sample, such that its optical axis follows a direction perpendicular to the inspection target film formed on the sample. Since the probe light (26) and pump light (27) are focused onto the sample (16) by the optical lens (141), measurement with high spatial resolution becomes possible. A charged particle source (12) is positioned obliquely with respect to the optical axis of the optical lens (141), and a charged particle beam (13) passes between the optical lens (141) and the sample (16) and is irradiated obliquely onto the sample (16). Additionally, to shorten the distance between the optical lens (141) and the sample (16), the optical lens (141) also functions as a charge control electrode. That is, a transparent conductive film (17b) is formed on the optical lens (141) so that the probe light (26), pump light (27), and signal light (28) can be transmitted, and a voltage can be applied by the control device (30). As the material for the transparent conductive film (17b), ITO, ITZO, etc., may be used, or a metal thin film such as aluminum or gold may be used. In addition, instead of forming the film on the optical lens (141), the charge control electrode may be made into a transparent electrode and placed below the optical lens (141) separately from the optical lens (141). The probe light (26) and pump light (27) are integrated on the same optical path using a dichroic mirror (142) that has different transmission and reflection characteristics depending on the wavelength of the light. The signal light (28) diverts the optical path of the probe light (26) in the opposite direction, is reflected by the beam splitter (143), passes through the optical filter (23), and is detected by the light detection system (24). In this way, the inspection device (4) can perform film quality measurement with high spatial resolution by focusing the probe light (26) onto the sample (16) by the optical lens (141).In addition, since the optical lens (141) is placed near the sample (16), it also has the advantage of improving the detection rate of scattered light or light emission from the sample (16). Also, FIG. 14 illustrates only representative optical components constituting the optical system, and general elements such as lenses and mirrors are omitted from the illustration.

[0077] The present invention has been described above with reference to embodiments and modifications. The above-described embodiments and modifications can be modified in various ways without altering the essence of the invention, and it is also possible to use them in combination. Explanation of the symbols

[0078] 1, 2, 3, 4: Inspection device 10: Sample Room 11: Telescope tube 12: Charged particle source 13: Charged particle beam 14: Blanker 15: Viewport 16: Sample 17: Charging control electrode 17b: Transparent conductive film 21: First light source 22: Second light source 23: Optical filter 24: Photodetection System 25: Signal processing unit 26: Probe light 27: Pump Light 28: Signal Light 30: Control unit 31: Calculator 41, 51: Database 60: Wafer Heat Map 61: Wafer 62: Chip Section 70: Settings / Measurement Screen 71: Configuration File Selection 72: Settings tab 73: Laser Modulation Tab 74: Sequence diagram 75: Electron beam condition setting section 76: Charging control electrode condition setting unit 77: Laser condition setting section 78: Small Person Range Setting Section 79: Save button 81: Measurement tab 82: Inspection chip compartment setting section 83: Run scan button 84: Wafer heatmap display 85: Save button 90: Result Output Screen 91: Result File Selection 92: Wafer Heatmap Display 93: Histogram display 94: Inspection chip compartment measurement result display 100: Signal Electronics 101: Energy Filter 102: Signal electronic detector 103, 104, 105: Signal electronic spectrum 110: Surface potential meter 120: Bulkhead 131: Third Light Source 132: The Fourth Light Source 133: The 1st Heretic 134: The 2nd Heretic 135: The first photoelectron 136: Second Photoelectron 141: Optical lens 142: Dichroic Mirror 143: Beam Splitter

Claims

Claim 1 An inspection device for inspecting the film quality of a film formed on a sample, comprising: a charged particle source for irradiating a charged particle beam onto the sample; a first light source for irradiating a first light onto the sample; a light detector for detecting a signal light generated by the irradiation of the first light onto the sample; a charge control electrode for controlling an electric field on the sample or a second light source for irradiating a second light onto the sample; a control device for modulating the electronic state of the sample using the charged particle source, the charge control electrode, or the second light source; and a calculator for estimating the film quality of the film formed on the sample based on a detection signal of the signal light sampled in synchronization with the modulation of the electronic state of the sample output from the light detector. Claim 2 In claim 1, the control device has both the charge control electrode and the second light source, and uses at least one of the charged particle source, the charge control electrode, and the second light source to modulate the electronic state of the sample. Claim 3 In paragraph 2, the light detector is an inspection device that outputs a detection signal indicating a change in the signal light caused by modulation of the electronic state of the sample. Claim 4 In paragraph 3, the detection signal is expressed by a model equation including a plurality of fit parameters, and the calculator has a database that registers film quality information for a combination of the plurality of fit parameters, and a testing device that fits the detection signal to the model equation to calculate the plurality of fit parameters of the detection signal and compares the calculated plurality of fit parameters with the database. Claim 5 In paragraph 3, the control device is an inspection device that modulates the second light source while changing the electric field strength applied to the sample by the charge control electrode. Claim 6 In claim 5, the detection signal has a dependency on the electric field strength applied to the sample, and the calculator has a database that registers film quality information regarding a feature quantity indicating the dependency, calculates the feature quantity indicating the dependency from the detection signal, and compares the calculated feature quantity indicating the dependency with the database. Claim 7 In claim 6, the inspection device has a signal electron detector that detects signal electrons generated by the charge electron beam being irradiated onto the sample, and the calculator calculates the surface potential of the sample based on the energy of the signal electrons detected by the signal electron detector. Claim 8 In claim 6, an inspection device having a surface potential meter for measuring the surface potential of the sample. Claim 9 In claim 1, the sample is placed in the atmosphere, the charged particle source is placed in a tube having a partition to maintain the charged particle source in a vacuum atmosphere, and the charged particle beam penetrates the partition and is irradiated onto the sample. Claim 10 In claim 1, the sample and the charged particle source are placed in the atmosphere, and the charged particle source is an electrode that generates ions by corona discharge. Claim 11 In claim 1, the inspection device wherein the first light is irradiated onto the sample from a direction perpendicular to the film formed on the sample, and the charged particle beam is irradiated onto the sample from an angle with respect to the film formed on the sample. Claim 12 In claim 11, an inspection device having an optical lens that concentrates the first light, and a conductive film that serves as the charge control electrode formed on the sample-side surface of the optical lens. Claim 13 In claim 11, an inspection device having an optical lens that concentrates the first light, wherein the charge control electrode is a transparent electrode disposed between the optical lens and the sample. Claim 14 An inspection device for inspecting the film quality of a film formed on a sample, comprising: a first light source for irradiating a first light onto the sample; a light detector for detecting a signal light generated by the irradiation of the first light onto the sample; a charge control electrode for controlling an electric field on the sample; a third light source for generating photoelectrons by irradiating a third light onto the charge control electrode; a fourth light source for generating photoelectrons by irradiating a fourth light onto the sample; a control device for modulating the electronic state of the sample by controlling the voltage applied to the charge control electrode, the third light source, and the fourth light source; and a calculator for estimating the film quality of a film formed on the sample based on a detection signal of the signal light sampled in synchronization with the modulation of the electronic state of the sample output from the light detector. Claim 15 A film quality inspection method for inspecting the film quality of a film formed on a sample, wherein the method irradiates a charged particle beam onto the sample to charge the sample, irradiates a probe light onto the sample while the electronic state of the sample is modulated, detects a signal light generated by the irradiation of the probe light onto the sample, and estimates the film quality of the film formed on the sample based on the detection signal of the signal light sampled in synchronization with the modulation of the electronic state of the sample. Claim 16 A film quality inspection method according to claim 15, wherein the probe light is irradiated onto the sample while the electronic state of the sample is modulated by varying the electric field strength applied to the sample, and the film quality of the film formed on the sample is estimated based on the electric field strength dependence of the detection signal of the signal light sampled in synchronization with the modulation of the electronic state of the sample.

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