JP6796517B2 - Charged particle beam device - Google Patents

Description

The present invention relates to a charged particle beam device.

Electron probe microanalyzer (EPMA) and scanning electron microscope (EPMA) and scanning electron microscope.
An electron gun is used in a charged particle beam device including an analyzer such as a Microscope (SEM) and an Auger Electron Spectrometer, and a processing device such as an electron beam vapor deposition device. In addition, an electron gun is also used to generate X-rays in a charged particle beam device such as an X-ray Photoelectron Spectroscopy (XPS) that irradiates a sample with X-rays for analysis. ..

In such a charged particle beam device, it is necessary to adjust the irradiation amount (probe current amount) of the electron beam emitted from the electron gun.

For example, Patent Document 1 discloses a probe current setting method for an electron beam device that can automatically select the diameter of an objective diaphragm and the interlocking ratio of a condenser lens to optimum values and set the target probe current amount. Has been done. In Patent Document 1, a table of probe current and accelerating voltage (first table) and a table for selecting an equation for determining the exciting current amount of the focusing lens from the accelerating voltage and the diameter of the objective aperture (second table) are prepared in advance. , Set the probe current amount using these tables.

Japanese Unexamined Patent Publication No. 6-236743

However, in the charged particle beam device as described above, the filament of the electron gun is consumed and the irradiation amount of the electron beam changes. For example, in the case of a thermionic emission type electron gun, the filament (emitter) is consumed in about one to several months. Therefore, when setting the probe current amount using the above table, the user needs to update the table frequently in order to set the probe current amount accurately.

The present invention has been made in view of the above problems, and one of the objects according to some aspects of the present invention is to easily and accurately control the irradiation amount of charged particle beams. The purpose is to provide a charged particle beam device capable of this.

(1) The charged particle beam apparatus according to the present invention is
Charged particle beam source and
An optical system that controls the irradiation amount of charged particle beams that irradiate the irradiation target,
An irradiation amount measuring unit that measures the irradiation amount of the charged particle beam irradiated to the irradiation target,
A storage unit that stores historical information associated with the irradiation amount of the charged particle beam and the optical conditions of the optical system.
A control unit that controls the optical system based on the history information and updates the history information based on the controlled optical conditions of the optical system.
Only including,
The control unit
The first process of determining whether or not there is an irradiation amount that matches the target irradiation amount from the irradiation amount information included in the history information, and
When it is determined that there is a match in the first process, the optical system is controlled based on the optical conditions of the optical system included in the history information and associated with the information of the matched irradiation dose. 2 processing and
To do .

In such a charged particle beam device, even if the amount of charged particle beams emitted from the charged particle beam source changes due to deterioration of the filament or replacement of the filament, the user can use the irradiation amount and the optical conditions of the optical system. There is no need to update the table etc. associated with. Therefore, in such a charged particle beam device, the irradiation amount of the charged particle beam can be easily and accurately controlled. In particular, the irradiation amount that is frequently set can be set in a short time. Further, in such a charged particle beam device, since the optical system is controlled based on the history information, the number of times of measuring the irradiation amount of the charged particle beam can be reduced for the irradiation amount frequently set, and the charged particle beam can be measured. The irradiation amount can be set in a short time.

(2) In the charged particle beam apparatus according to the present invention.
The control unit
An error of the irradiation amount measured by the irradiation amount measuring unit with respect to the target irradiation amount is calculated, and when the error is less than a predetermined value, the target irradiation amount is stored in the storage unit in association with the optical conditions of the optical system. The history information may be updated.

In such a charged particle beam device, since the control unit updates the history information, the user does not need to update the table or the like that associates the irradiation amount with the optical conditions of the optical system, and the charged particle beam can be easily and accurately measured. The irradiation amount can be controlled.

( 3 ) In the charged particle beam apparatus according to the present invention.
Includes an optical system drive unit that drives the optical system based on a control signal from the control unit.
The optical system drive unit
A first irradiation amount changing unit that changes the irradiation amount of the charged particle beam irradiated to the irradiation target in the first step width, and
A second irradiation amount changing unit that changes the irradiation amount of the charged particle beam irradiated to the irradiation target with a second step width larger than the first step width, and
Have,
The control unit
After the second treatment, a third treatment for acquiring information on the irradiation amount measured by the irradiation amount measuring unit, and
The fourth process of calculating the error of the irradiation amount measured by the irradiation amount measuring unit with respect to the target irradiation amount, and
The fifth process of controlling the first irradiation amount changing unit so that the irradiation amount becomes the target irradiation amount when the error is equal to or more than the first value and less than the second value.
The sixth process of controlling the second irradiation amount changing unit so that the irradiation amount becomes the target irradiation amount when the error is equal to or more than the second value.
May be done.

In such a charged particle beam device, the irradiation amount of the charged particle beam can be set in a wide range and with high accuracy.

( 4 ) In the charged particle beam apparatus according to the present invention.
The control unit
When the error is less than the first value, the seventh process of renewing the history information by associating the target irradiation amount with the optical conditions of the optical system in the second process and storing them in the storage unit. May be done.

In such a charged particle beam device, since the control unit updates the history information, the user does not need to update the table or the like that associates the irradiation amount with the optical conditions of the optical system, and the charged particle beam can be easily and accurately measured. The irradiation amount can be controlled.

( 5 ) In the charged particle beam apparatus according to the present invention.
In the fifth process,
After controlling the first irradiation amount changing unit, a process of acquiring information on the irradiation amount measured by the irradiation amount measuring unit and calculating an error with respect to the target irradiation amount, and
The process of determining whether the error is greater than or equal to the predetermined value,
And
When it is determined that the error is equal to or more than a predetermined value, after controlling the first irradiation amount changing unit again, the irradiation amount information measured by the irradiation amount measuring unit is acquired and the error with respect to the target irradiation amount is calculated. And the process of determining whether the error is greater than or equal to the specified value.
When the number of times these processes are repeated is a predetermined number of times or more, the eighth process may be performed to delete the information of the irradiation amount that matches the target irradiation amount from the history information.

In such a charged particle beam device, data unnecessary for setting the irradiation amount of the charged particle beam can be deleted from the history information.

( 6 ) In the charged particle beam apparatus according to the present invention.
In the sixth process,
After controlling the second irradiation amount changing unit, a process of acquiring information on the irradiation amount measured by the irradiation amount measuring unit and calculating an error with respect to the target irradiation amount, and
The process of determining whether the error is greater than or equal to the predetermined value,
And
When it is determined that the error is equal to or more than a predetermined value, the error with respect to the target irradiation amount is calculated by acquiring the irradiation amount information measured by the irradiation amount measuring unit after controlling the second irradiation amount changing unit again. And the process of determining whether the error is greater than or equal to the specified value.
When the number of times these processes are repeated is a predetermined number of times or more, the ninth process may be performed to delete the information of the irradiation amount that matches the target irradiation amount from the history information.

In such a charged particle beam device, data unnecessary for setting the irradiation amount of the charged particle beam can be deleted from the history information.

( 7 ) In the charged particle beam apparatus according to the present invention.
The charged particle beam source may be a thermionic emission type electron gun.

In such a charged particle beam device, even if the amount of charged particle beam emitted from the electron gun changes due to deterioration of the filament of the electron gun, replacement of the filament, etc., the user can determine the irradiation amount and the optical conditions of the optical system. There is no need to update the associated table etc. Therefore, in such a charged particle beam device, the irradiation amount of the charged particle beam can be easily and accurately controlled.

( 8 ) In the charged particle beam apparatus according to the present invention.
The irradiation target may be an X-ray target that generates X-rays by being irradiated with charged particle beams.

( 9 ) In the charged particle beam apparatus according to the present invention.
The irradiation target may be an evaporative material that evaporates when the charged particle beam is irradiated.

The figure which shows the structure of the electron probe microanalyzer which concerns on this embodiment. The figure for demonstrating the fine adjustment circuit and the coarse adjustment circuit. The flowchart which shows an example of the processing flow of the processing part of the electron probe microanalyzer which concerns on this embodiment. The flowchart which shows an example of the process of setting a circuit for rough adjustment. The flowchart which shows an example of the process of setting a circuit for fine adjustment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the embodiments described below do not unreasonably limit the contents of the present invention described in the claims. Moreover, not all of the configurations described below are essential constituent requirements of the present invention.

Further, in the following, as the charged particle beam device according to the present invention, an electron probe microanalyzer (EPMA) that irradiates an electron beam for analysis will be described as an example, but the charged particle beam device according to the present invention is an electron. It may be a device that performs analysis and processing by irradiating a charged particle beam (ion or the like) other than the line. The charged particle beam apparatus according to the present invention includes, for example, an analyzer equipped with an electron gun such as a scanning electron microscope (SEM), an Auger electron spectroscope, an X-ray photoelectron spectroscope, and an electron gun such as an electron beam vapor deposition apparatus. It may be a processing device.

1. 1. Electron probe microanalyzer First, the electron probe microanalyzer according to this embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of an electron probe microanalyzer 100 according to the present embodiment.

The electron probe microanalyzer 100 is a device that irradiates a sample S with an electron beam EB and detects and analyzes characteristic X-rays generated from the sample S in response to the irradiation of the electron beam EB. As shown in FIG. 1, the electron probe microanalyzer 100 includes an electron gun 11, a focusing lens 12, a deflector 13, an objective lens 14, a sample stage 15, a secondary electron detector 17, and an energy dispersion type. X-ray detector 18, wavelength-dispersed X-ray spectrometer 19, Faraday cup 20, current meter 22, focused lens drive device 30 (an example of optical system drive unit), processing unit 40, and operation unit 50. , A display unit 52, and a storage unit 54.

The electron gun 11 generates an electron beam EB. The electron gun 11 emits an electron beam EB accelerated by a predetermined accelerating voltage toward the sample S. The electron gun 11 is, for example, a thermionic emission type electron gun. The thermionic emission type electron gun is an electron gun that utilizes a phenomenon (thermionic emission) in which electrons are emitted into a vacuum through an energy barrier when a metal is heated at a high temperature. For the cathode of the thermionic emission type electron gun, for example, a tungsten filament, a lanthanum hexaboride chip (LaB ₆ ), or the like is used.

The focusing lens 12 is arranged at the rear stage (downstream side of the electron beam EB) of the electron gun 11. The focusing lens 12 is a lens for focusing the electron beam EB. The focusing lens 12 controls the irradiation amount (irradiation current amount) of the electron beam EB irradiated to the sample S, that is, the probe current amount. The probe current amount is the amount of current flowing in the electron probe (electron beam EB) irradiated to the sample S.

The deflector 13 is arranged after the focusing lens 12. The deflector 13 can deflect the electron beam EB.

The objective lens 14 is arranged after the deflector 13. The objective lens 14 focuses the electron beam EB and irradiates the sample S.

The sample stage 15 can support the sample S. Sample S is placed on the sample stage 15. Although not shown, the sample stage 15 can be moved by a stage moving mechanism including a drive source such as a motor.

The secondary electron detector 17 is a detector for detecting the secondary electrons emitted from the sample S. The output signal of the secondary electron detector 17 is stored in the storage device in synchronization with the scanning signal of the electron beam EB. As a result, a secondary electron image (SEM image) can be obtained.

The energy dispersive X-ray detector 18 is a detector for discriminating X-rays by energy and obtaining a spectrum. The energy dispersive X-ray detector 18 detects characteristic X-rays generated from the sample S by irradiating the sample S with an electron beam EB.

The wavelength dispersive X-ray spectroscope 19 is configured to include a plurality of spectroscopic elements (spectral crystals) 19a and an X-ray detector 19b. The wavelength dispersive X-ray spectroscope 19 has a plurality of spectroscopic elements 19a having different crystal plane spacing in order to enable measurement in a wide wavelength range. The wavelength dispersion type X-ray spectroscope 19 separates the characteristic X-rays generated from the sample S into X-rays having a specific wavelength by using Bragg reflection in the spectroscopic element 19a, and detects them with the X-ray detector 19b.

The Faraday cup 20 is a device for measuring the probe current. The Faraday cup 20 includes a conductive (for example, metal) cup that captures electrons (electron beam EB) emitted from the electron gun 11. The electrons (electron beam EB) captured by the Faraday cup 20 are measured as an electric current by the ammeter 22. The Faraday cup 20 and the ammeter 22 function as an irradiation amount measuring unit for measuring the irradiation amount (probe current) of the electron beam EB irradiated to the sample S. The irradiation amount measuring unit for measuring the probe current is not limited to the Faraday cup 20 and the ammeter 22.

In the example shown in FIG. 1, the Faraday cup 20 is arranged after the focusing lens 12. The Faraday cup 20 is arranged between the focusing lens 12 and the deflector 13. FIG. 1 illustrates a state in which the Faraday cup 20 is arranged on the optical axis of the optical system and the probe current is measured by the Faraday cup 20. Although not shown, the Faraday cup 20 is retracted from the optical axis when the sample S is irradiated with the electron beam EB.

The focusing lens driving device 30 drives the focusing lens 12 based on a control signal from the processing unit 40. The focusing lens drive device 30 includes a fine adjustment circuit 32 (fine adjustment circuit, first irradiation amount changing unit), a coarse adjustment circuit 34 (course adjustment circuit, second irradiation amount changing unit), and a focusing lens. It is configured to include a power supply 36.

The fine adjustment circuit 32 changes the probe current in the first step width. The coarse adjustment circuit 34 changes the probe current with a second step width larger than the first step width. That is, the fine adjustment circuit 32 is used for finely adjusting the probe current amount, and the coarse adjustment circuit 34 is used for rough adjustment of the probe current amount. The first step width may or may not be evenly spaced. Further, the second step width may or may not be evenly spaced. In either case, the second step width is larger than the first step width.

Since the focusing lens driving device 30 has the fine adjustment circuit 32 and the coarse adjustment circuit 34, the probe current can be set in a wide range and with high accuracy.

The fine adjustment circuit 32 and the coarse adjustment circuit 34 receive a control signal (digital signal) from the processing unit 40 and send an analog signal based on the control signal to the focusing lens power supply 36. The focusing lens power supply 36 superimposes (adds) the output signal (DAC output) of the fine adjustment circuit 32 and the output signal (DAC output) of the coarse adjustment circuit 34, and is based on the superposed (added) signal. The exciting current is supplied to the focusing lens 12.

FIG. 2 is a diagram for explaining a fine adjustment circuit 32 and a coarse adjustment circuit 34.

FIG. 2 shows a lens set value (DAC output) output from the fine adjustment circuit 32 and a lens set value (DAC output) output from the coarse adjustment circuit 34. The lens set value is obtained by replacing the exciting current supplied to the focusing lens 12 so that the probe current amount changes according to a predetermined function. For example, it may be a function in which the logarithm of the probe current amount has a linear relationship with the lens set value. Specifically, when the lens setting value of the fine adjustment circuit 32 and a CL _F, probe current amount Ir is
logIr = CL _F × a + b ... (1)
It is represented by. However, a and b are arbitrary numbers.

Further, when the lens setting value of the rough adjustment circuit 34 and a CL _C, probe current amount Ir is
logIr = CL _C x c + d ... (2)
It is represented by. However, c and d are arbitrary numbers.

The interval between the lens set values of the coarse adjustment circuit 34 is larger than the interval between the lens set values of the fine adjustment circuit 32. In the example shown in FIG. 2, the interval between the lens set values of the coarse adjustment circuit 34 is eight times the interval between the lens set values of the fine adjustment circuit 32. The adjustable range of the fine adjustment circuit 32 is larger than the interval between the lens set values of the coarse adjustment circuit 34. The center of the adjustable range of the fine adjustment circuit 32 (between "8" and "9" in the illustrated example) should be located at the center (or substantially the center) of the interval between the lens set values of the coarse adjustment circuit 34. It is configured in.

The operation unit 50 acquires an operation signal according to the operation by the user and sends the operation signal to the processing unit 40. The operation unit 50 is, for example, a button, a key, a touch panel type display, a microphone, or the like.

The display unit 52 displays an image generated by the processing unit 40, and its function can be realized by an LCD, a CRT, or the like.

The storage unit 54 stores programs, data, and the like for the processing unit 40 to perform various calculation processes. The storage unit 54 is also used as a work area of the processing unit 40, and is also used to temporarily store the calculation results and the like executed by the processing unit 40 according to various programs. The function of the storage unit 54 can be realized by a hard disk, RAM, or the like.

History information 2 is stored in the storage unit 54. The history information 2 is information in which the probe current amount and the optical conditions of the focusing lens 12 are associated with each other. More specifically, the history information 2 describes the optical conditions of the focusing lens 12 when the error between the probe current amount set so far by the electron probe microanalyzer 100 and the set probe current amount is less than a predetermined value. Is the information associated with. In the history information 2, for example, the probe current amount and the optical conditions of the focusing lens 12 are listed. The optical condition of the focusing lens 12 is represented by, for example, the amount of exciting current supplied to the focusing lens 12. The optical conditions of the focusing lens 12 may be represented by the lens set value of the fine adjustment circuit 32 and the lens set value of the coarse adjustment circuit 34.

The above formula (1) and the above formula (2) are further stored in the storage unit 54.

As described in "2. Processing" described later, the processing unit 40 (CPU) controls the focusing lens 12 based on the history information 2, and updates the history information 2 based on the optical conditions of the controlled focusing lens 12. Processing, processing to delete a part of history information 2, and the like. In this way, the processing unit 40 functions as a control unit that controls the focusing lens 12.

Further, the processing unit 40 performs a process of storing the optical conditions of the focusing lens 12 in the storage unit 54. For example, when the optical condition of the focusing lens 12 is changed, the processing unit 40 updates the optical condition of the focusing lens 12 stored in the storage unit 54. That is, the current optical conditions of the focusing lens 12 can be obtained by reading out the optical conditions of the focusing lens 12 stored in the storage unit 54.

Further, the processing unit 40 performs various processing according to the operation signal from the operation unit 50, processing for displaying various information on the display unit 52, and the like. The function of the processing unit 40 can be realized by executing the program stored in the storage unit 54 by various processors (CPU or the like).

2. 2. Processing Next, a processing for controlling the focusing lens 12 of the processing unit 40, that is, a processing for setting the probe current will be described with reference to the drawings. FIG. 3 is a flowchart showing an example of the processing flow of the processing unit 40 of the electron probe microanalyzer 100.

First, the processing unit 40 determines whether or not the user has given an instruction to start setting the probe current (start instruction) (step S10), and waits until the start instruction is given (NO in step S10). The processing unit 40 determines that the user has given the start instruction, for example, when the start instruction is input from the operation unit 50.

When it is determined that the start instruction has been given (YES in step S10), the processing unit 40 determines whether or not the probe current has been measured (step S12). When the measurement result of the probe current amount is stored in the storage unit 54, the processing unit 40 determines that the probe current has been measured (measured).

When the processing unit 40 determines that the probe current is being measured (YES in step S12), the processing unit 40 reads out the probe current amount stored in the storage unit 54 and acquires information on the current probe current amount.

For example, in the case where the Faraday cup 20 is arranged on the optical axis except when the EPMA is measured, the measurement result of the probe current immediately before the start instruction is given is stored in the storage unit 54. Therefore, the measurement result of the probe current stored in the storage unit 54 can be used as the probe current amount under the current optical conditions of the focusing lens 12. Therefore, it is not necessary to perform the process of step S14 described later, and the number of times the probe current is measured using the Faraday cup 20 can be reduced after the start instruction is given. As a result, the time required to set the probe current can be shortened. Since the amount of probe current is very small, it takes time to measure the amount of probe current. Therefore, reducing the number of times the probe current is measured is particularly effective in reducing the time required to set the probe current.

When the processing unit 40 determines that the probe current has not been measured (NO in step S12), the processing unit 40 acquires the measurement result of the current probe current amount from the ammeter 22 (step S14). At this time, the Faraday cup 20 is arranged on the optical axis, and the electrons (electron beam EB) captured by the Faraday cup 20 are measured as an electric current by the ammeter 22. The processing unit 40 acquires this measurement result.

Next, the processing unit 40 compares the acquired probe current amount (current probe current amount) with the target current amount (target irradiation amount). Specifically, the processing unit 40 calculates an error E (E = | probe current amount-target current amount | / target current amount) of the acquired probe current amount (current probe current amount) with respect to the target current amount. Then, the processing unit 40 determines whether the calculated error E is less than A% or more than A% (step S16).

The target current amount can be set to an arbitrary value, and can be set by, for example, the user operating the operation unit 50. Further, "A%" represents the accuracy when setting the probe current amount, and can be appropriately set according to the required accuracy of the probe current amount.

When the processing unit 40 determines that the error E is less than A% (E <A in step S16), the processing is terminated because the required accuracy of the probe current amount is satisfied.

When the processing unit 40 determines that the error E is A% or more (E ≧ A in step S16), the processing unit 40 uses information (list) of the probe current amount included in the history information 2 stored in the storage unit 54. It is determined whether or not there is something that matches the target current amount (step S18).

When the processing unit 40 determines that there is information (list) of the probe current amount included in the history information 2 that matches the target current amount (YES in step S18), the processing unit 40 is included in the history information 2. Information on the optical conditions of the focusing lens 12 associated with the information on the matched probe current amount is acquired (step S20).

Next, the processing unit 40 controls the optical conditions of the focusing lens 12 based on the history information 2 (step S24). Specifically, the processing unit 40 generates a control signal for setting the optical condition of the focusing lens 12 to the optical condition of the focusing lens 12 acquired in step S20, which is included in the history information 2. The processing unit 40 sends the generated control signal to the focusing lens driving device 30. As a result, the focusing lens driving device 30 drives the focusing lens 12 based on the control signal, and the focusing lens 12 becomes an optical condition included in the history information 2.

Next, the processing unit 40 acquires the measurement result of the current probe current amount from the ammeter 22 (step S26).

Next, the processing unit 40 compares the acquired probe current amount (current probe current amount) with the target current amount. Specifically, the processing unit 40 calculates an error E of the acquired probe current amount (current probe current amount) with respect to the target current amount. Then, the processing unit 40 determines whether the obtained error E is less than A%, A% or more and less than B%, or B% or more (step S28).

Note that "B%" is set based on, for example, the adjustable range of the fine adjustment circuit 32, and when the error E is less than B%, the difference between the current probe current amount and the target current amount is for fine adjustment. The value is set so as to be included in the adjustable range of the circuit 32.

When the processing unit 40 determines that the error E is less than A% (E <A in step S28), the processing for setting the probe current is stopped because the required accuracy of the probe current amount is satisfied. (Step S36).

When the processing unit 40 determines that the error E is A% or more and less than B% (A ≦ E <B in step S28), the processing unit 40 makes a rough adjustment as a preliminary step for setting the fine adjustment circuit 32 (step S34). The circuit 34 is set (step S30).

Specifically, the current lens setting value of the fine adjustment circuit 32 is close to the lower limit (for example, in the example shown in FIG. 2, when the lens setting value of the fine adjustment circuit 32 is "3" or less), the target current amount. The difference between the current probe current and the current probe current is negative (target current amount-current probe current amount <0), and the lens setting value of the coarse adjustment circuit 34 is not the lower limit (rough adjustment in the example shown in FIG. 2). When the lens set value of the circuit 34 for circuit 34 is not "1"), the lens set value of the coarse adjustment circuit 34 is set to "-1". For example, if the current lens setting value of the coarse adjustment circuit 34 is "3" and the above conditions are satisfied, the lens setting value of the coarse adjustment circuit 34 is set to "2".

Further, the lens setting value of the current fine adjustment circuit 32 is close to the upper limit (for example, when it is "14" or more in the example shown in FIG. 2), and the difference between the target current amount and the current probe current is positive (for example, when it is "14" or more). Target current amount-Current probe current amount> 0), and the lens setting value of the coarse adjustment circuit 34 is not the upper limit (when it is not "5" in the example shown in FIG. 2), the lens of the coarse adjustment circuit 34 Set the value to "+1". For example, if the current lens setting value of the coarse adjustment circuit 34 is "3" and the above conditions are satisfied, the lens setting value of the coarse adjustment circuit 34 is set to "4".

If these conditions are not satisfied, the processing unit 40 does not change the lens setting value of the coarse adjustment circuit 34.

As described above, by setting the coarse adjustment circuit 34 as a preliminary step before setting the fine adjustment circuit 32, the lens of the fine adjustment circuit 32 is set in the setting of the fine adjustment circuit 32 (step S34). The set value can be a value near the center of the adjustable range. As a result, when setting the fine adjustment circuit 32 (step S34), it is possible to prevent the fine adjustment circuit 32 from exceeding the adjustable range.

After setting the coarse adjustment circuit 34 (step S30), the processing unit 40 sets (controls) the fine adjustment circuit 32 so that the probe current becomes the target current amount (step S34).

When the processing unit 40 determines that the error E is B% or more (E ≧ B in step S28), the processing unit 40 sets (controls) the rough adjustment circuit 34 so that the probe current becomes the target current amount (step S32). , And the setting (control) of the fine adjustment circuit 32 (step S34).

Further, when the processing unit 40 determines that none of the probe current amount information included in the history information 2 matches the target current amount (NO in step S18), the error E is B% or more. In the same manner as in the case of determining that (E ≧ B in step S28), the coarse adjustment circuit 34 is set (step S32) and the fine adjustment circuit 32 is set (step S34).

The process of setting the coarse adjustment circuit 34 (step S32) and setting the fine adjustment circuit 32 (step S34) will be described later.

After setting the fine adjustment circuit 32 so that the probe current amount becomes the target current amount (after step S34), the processing unit 40 stops the process of setting the probe current (step S36).

Next, the processing unit 40 updates (or adds) the history information 2 (step S38). Specifically, the processing unit 40 stores the target current amount and the optical condition of the focusing lens 12 when the error E is determined to be less than A% in the storage unit 54 as history information 2. At this time, if the history information 2 includes information on the same probe current amount as the target current amount, the information on the optical conditions of the focusing lens 12 associated with the probe current amount is updated. If the history information 2 does not include the target current amount, information on the target current amount and the optical conditions of the focusing lens 12 is newly added to the history information 2.

The information on the optical conditions of the focusing lens 12 when the error E is determined to be less than A% in the process of step S38 is the case where the error E is determined to be less than A% in step S28 (step S28). E <A) is the optical condition of the focusing lens 12 set (controlled) in step S24. When the fine adjustment circuit 32 is set (step S34), the optical conditions of the focusing lens 12 set (controlled) in step S34 (more specifically, it is set in step S331 described later). Optical conditions of the focusing lens 12).

By the above processing, the probe current can be set.

FIG. 4 is a flowchart showing an example of a process (step S32) for setting (controlling) the fine adjustment circuit 32.

The processing unit 40 first sets the fine adjustment circuit 32 (step S321). Specifically, the lens setting value of the fine adjustment circuit 32 is set near the center (“8” or “9” in the example shown in FIG. 2). As a result, in the setting of the fine adjustment circuit 32 (step S34), the lens setting value of the fine adjustment circuit 32 can be set to a value near the center of the adjustable range. As a result, when setting the fine adjustment circuit 32 (step S34), it is possible to prevent the fine adjustment circuit 32 from exceeding the adjustable range.

Next, the processing unit 40 acquires the measurement result of the current probe current amount from the ammeter 22 (step S322).

Next, the processing unit 40 sets the coarse adjustment circuit 34 (sets the lens set value) based on the difference between the target current amount and the current probe current amount (probe current amount acquired in step S322). (Step S323).

For example, when the difference between the target current amount and the current probe current is negative (target current amount − current probe current amount <0), the processing unit 40 sets the lens setting value of the coarse adjustment circuit 34 to “-1”. To do. Further, when the difference between the target current amount and the current probe current is positive (target current amount-current probe current amount> 0), the processing unit 40 sets the lens setting value of the coarse adjustment circuit 34 to "+1". ". If the difference between the target current amount and the current probe current amount is large, the lens setting value of the coarse adjustment circuit 34 may be changed according to the difference. That is, the larger the difference, the greater the degree of change in the lens set value.

Next, the processing unit 40 acquires the measurement result of the current probe current amount from the ammeter 22 (step S324).

The processing unit 40 compares the acquired probe current amount (current probe current amount) with the target current amount. Specifically, the processing unit 40 calculates an error E of the acquired probe current amount (current probe current amount) with respect to the target current amount. Then, the processing unit 40 determines whether the obtained error E is less than C% or C% or more (step S325).

Note that "C%" is set based on the interval between the lens set values of the coarse adjustment circuit 34. For example, when the error E is less than "C%", the target current amount and the current probe current amount are used. The difference is set to a value smaller than the interval (one scale) of the lens set values of the coarse adjustment circuit 34.

When the processing unit 40 determines that the error E is C% or more (E ≧ C in step S325), the processing unit 40 determines whether or not the processing in step S323, the processing in step S324, and the processing in step S325 are repeated a predetermined number of times or more. Process (step S326).

When the processing unit 40 determines that the processing of steps S323 to S325 has not been repeated more than a predetermined number of times (NO in step S326), the processing unit 40 returns to step S323 and returns to step S323 processing, step S324 processing, and step S325. Perform processing. The processing unit 40 determines that the error E is less than C% (E <C in step S325), or it is determined that the processes of steps S323 to S325 are repeated a predetermined number of times or more (YES in step S326). ), The processing of steps S323 to S326 is repeated. The specified number of times in the process of step S326 can be set to an arbitrary number.

When the processing unit 40 determines that the error E is less than C% (E <C in step S325), the processing unit 40 sets the coarse adjustment circuit 34 (lens setting value set in the process of step S323) and measures in that setting. The above equation (2) stored in the storage unit 54 is updated based on the obtained probe current amount (probe current amount acquired in the process of step S324) (step S327). For example, the processing unit 40 acquires two or more combinations of the setting (lens setting value) of the coarse adjustment circuit 34 and the probe current amount, and obtains the values of “c” and “d” of the above equation (2). .. Then, the processing unit 40 updates the above formula (2) by changing the values of “c” and “d” of the above formula (2) stored in the storage unit 54 to newly obtained values.

By the above processing, the setting of the coarse adjustment circuit 34 is completed.

When it is determined that the processes of steps S323 to S325 have been repeated a predetermined number of times or more (YES in step S326), the processing unit 40 stops the process of setting the probe current (step S328).

Next, the processing unit 40 searches the history information 2 for information on the probe current amount that matches the target current amount. Then, when the processing unit 40 contains information on the probe current amount that matches the target current amount in the history information 2, the information on the probe current amount and the information on the probe current amount are obtained from the history information 2. The optical condition of the focusing lens 12 associated with is deleted (step S329). Then, the processing unit 40 ends the processing. If there is no information on the matching probe current amount, the processing unit 40 immediately ends the processing.

FIG. 5 is a flowchart showing an example of a process (step S34) for setting (controlling) the fine adjustment circuit 32.

First, the processing unit 40 sets the fine adjustment circuit 32 (sets the lens set value) based on the difference between the target current amount and the current probe current amount (step S331).

For example, when the difference between the target current amount and the current probe current is negative (target current amount − current probe current amount <0), the processing unit 40 sets the lens setting value of the fine adjustment circuit 32 to “-1”. To do. Further, when the difference between the target current amount and the current probe current is positive (target current amount-current probe current amount> 0), the processing unit 40 sets the lens setting value of the fine adjustment circuit 32 to "+1". ". If the difference between the target current amount and the current probe current amount is large, the lens setting value of the coarse adjustment circuit 34 may be changed according to the difference. That is, the larger the difference, the greater the degree of change in the lens set value.

Next, the processing unit 40 acquires the measurement result of the current probe current amount from the ammeter 22 (step S332).

The processing unit 40 compares the acquired probe current amount (current probe current amount) with the target current amount. Specifically, the processing unit 40 calculates an error E of the acquired probe current amount (current probe current amount) with respect to the target current amount. Then, the processing unit 40 determines whether the obtained error E is less than A% or more than A% (step S333).

When the processing unit 40 determines that the error E is A% or more (E ≧ A in step S333), the processing unit 40 determines whether or not the processing in step S331, the processing in step S332, and the processing in step S333 are repeated a predetermined number of times or more. Process (step S334).

When the processing unit 40 determines that the processes of steps S331 to S333 have not been repeated more than a predetermined number of times (NO in step S334), the processing unit 40 returns to step S331, and returns to step S331, steps S332, and steps S333. Perform processing. The processing unit 40 determines that the error E is less than A% (E <A in step S333), or it is determined that the processes of steps S331 to S333 have been repeated a predetermined number of times or more (YES in step S334). ), The processing of steps S331 to S334 is repeated. The specified number of times in the process of step S334 can be set to an arbitrary number.

When the processing unit 40 determines that the error E is less than A% (E <A in step S333), the processing unit 40 measures the setting of the fine adjustment circuit 32 (lens setting value set in the process of step S331) and the setting. The above equation (1) stored in the storage unit 54 is updated based on the obtained probe current amount (probe current amount acquired in the process of step S332) (step S335). For example, the processing unit 40 acquires two or more combinations of the setting (lens setting value) of the fine adjustment circuit 32 and the probe current amount, and obtains the values of “a” and “b” of the above equation (1). .. Then, the processing unit 40 updates the above formula (1) by changing the values of "a" and "b" of the above formula (1) stored in the storage unit 54 to newly obtained values.

By the above processing, the setting of the fine adjustment circuit 32 is completed.

When it is determined that the processes of steps S331 to S333 have been repeated a predetermined number of times or more (YES in step S334), the processing unit 40 stops the process of setting the probe current (step S336).

Next, the processing unit 40 searches the history information 2 for information on the probe current amount that matches the target current amount. Then, when the processing unit 40 contains information on the probe current amount that matches the target current amount in the history information 2, the information on the probe current amount and the information on the probe current amount are obtained from the history information 2. The optical condition of the focusing lens 12 associated with is deleted (step S337). Then, the processing unit 40 ends the processing. If there is no information on the matching probe current amount, the processing unit 40 immediately ends the processing.

The electron probe microanalyzer 100 has the following features, for example.

In the electron probe microanalyzer 100, the processing unit 40 controls the focusing lens 12 based on the history information 2, and updates the history information 2 based on the controlled optical conditions of the focusing lens 12. Therefore, in the electron probe microanalyzer 100, even if the amount of electron beam EB emitted from the electron gun 11 changes due to deterioration of the filament of the electron gun 11 or replacement of the filament, the user can use the probe current and the focusing lens. It is not necessary to update the table or the like associated with the 12 optical conditions. Further, once the probe current amount is set, the optical conditions of the focusing lens 12 at that time are stored, so that the number of times the probe current is measured can be reduced and the time for setting the probe current can be shortened. In particular, the probe current amount, which is frequently set, can often be set only by setting the optical conditions of the focusing lens 12 based on the history information 2, and the probe current can be set with high accuracy in a short time. Therefore, the electron probe microanalyzer 100 can easily and accurately control the probe current.

For example, when preparing a table or a function in which the probe current and the optical conditions of the focusing lens 12 are associated with each other in advance, the user may change the probe current amount due to deterioration of the filament of the electron gun 11 or replacement of the filament. You have to remake the table etc. On the other hand, in the electron probe microanalyzer 100, since the processing unit 40 updates the history information 2, the user does not need to update the table or the like.

Further, for example, in a method in which the probe current amount is measured while changing the optical conditions of the focusing lens 12 and the probe current amount is brought closer to the target current amount by the least squares method or the like, the number of times the probe current amount is measured increases. It ends up. Therefore, in the method using the least squares method, it takes time to set the probe current. On the other hand, in the electron probe microanalyzer 100, since the focusing lens 12 is controlled based on the history information 2, the number of times of measuring the probe current can be reduced as compared with the method using the least squares method, for example. The probe current can be set in a short time.

In the electronic probe microanalyzer 100, the processing unit 40 calculates an error E of the probe current amount measured by the Faraday cup 20 with respect to the target current amount, and when the calculated error E is less than a predetermined value, the target current amount. And the optical condition of the focusing lens 12 when the error E is determined to be less than A% are stored in the storage unit 54 in association with each other, and the history information 2 is updated (step S38). As described above, in the electron probe microanalyzer 100, since the processing unit 40 updates the history information 2, the user does not need to update the table or the like, and the probe current can be easily and accurately controlled.

In the electron probe microanalyzer 100, the processing unit 40 performs the first process (step S18) of determining whether or not there is a probe current amount that matches the target current amount from the information of the probe current amount included in the history information 2, and the corresponding When it is determined that there is a match in the first process, the second process of controlling the focusing lens 12 based on the optical conditions of the focusing lens 12 associated with the information of the probe current amount matching the target current amount ( Step S24) and.

In this way, the electron probe microanalyzer 100 can control the focusing lens 12 based on the history information 2. Therefore, for example, for a probe current that is frequently set, the number of times the probe current is measured by the Faraday cup 20 is reduced. The probe current can be set in a short time.

In the electronic probe microanalyzer 100, the processing unit 40 controls the focusing lens 12 based on the optical conditions of the focusing lens 12 associated with the information of the probe current amount that matches the target current amount (step S24). After, the third process (step S26) of acquiring the information of the probe current amount measured by the Faraday cup 20 and the fourth process (step S28) of calculating the error E of the measured probe current amount with respect to the target current amount. And, when the error E is A% (first value) or more and less than B% (second value), the fifth process (5th process) for controlling the fine adjustment circuit 32 so that the probe current amount becomes the target current amount. Step S34) and the sixth process (step S32) of controlling the coarse adjustment circuit 34 so that the probe current amount becomes the target current amount when the error E is B% or more are performed.

Therefore, in the electron probe microanalyzer 100, the probe current can be set in a wide range and with high accuracy.

In the electron probe microanalyzer 100, the processing unit 40 determines the target current amount when the error E is less than A% and the optical conditions of the focusing lens 12 when the error E is less than A% (step S24 or step). The seventh process (step S38) of associating with the optical condition of the focusing lens 12 set in S331 and storing it in the storage unit 54 is performed. In this way, in the electron probe microanalyzer 100, the processing unit 40 updates the history information 2, so that the probe current can be easily and accurately set.

In the electronic probe microanalyzer 100, in the fifth process (step S34) of controlling the fine adjustment circuit 32 so that the probe current amount becomes the target current amount, after setting the fine adjustment circuit 32 (after step S331). , When the process of acquiring the measured probe current amount information (step S332) and calculating the error E with respect to the target current amount (step S333) is performed and the error E is determined to be A% or more (E ≧ in step S333). In A), the processes of steps S331 to S333 are performed again, and when the number of times these processes (steps S331 to 333) are repeated is a predetermined number of times or more, the irradiation that matches the target current amount from the history information 2 is performed. The eighth process (step S337) of deleting the amount information is performed.

Therefore, in the electron probe microanalyzer 100, data unnecessary for setting the probe current can be deleted from the history information 2.

Further, in the electronic probe microanalyzer 100, in the sixth process (step S32) of controlling the coarse adjustment circuit 34 so that the probe current amount becomes the target current amount, after the rough adjustment circuit 34 is set (step S323). Later), when the information on the measured probe current amount is acquired (step S324) and the error E with respect to the target current amount is calculated (step S325) and the error E is determined to be C% or more (step S324). In E ≧ C), the processes of steps S323 to S325 are performed again, and when the number of times these processes (steps S323 to 325) are repeated is equal to or greater than a predetermined number of times, the target current amount is obtained from the history information 2. The ninth process (step S329) of deleting the information of the irradiation amount matching with is performed.

Therefore, in the electron probe microanalyzer 100, data unnecessary for setting the probe current can be deleted from the history information 2.

In the electron probe microanalyzer 100, the electron gun 11 is a thermionic emission type electron gun. In the case of a thermionic electron gun, the filament wears out in a short period of time (for example, one to several months). In the electron probe microanalyzer 100, even if the filament is worn out (or the filament is replaced), the user does not need to update the table or the like, so that the probe current can be set easily and accurately.

3. 3. Modifications The present invention is not limited to the above-described embodiment, and various modifications can be carried out within the scope of the gist of the present invention.

3.1. First Modification Example In the above-described embodiment, an example in which the focusing lens 12 is an optical system that controls the irradiation amount (that is, the probe current) of the electron beam irradiated to the sample S has been described, but the optical system that controls the probe current has been described. Is not limited to the focusing lens 12.

For example, the optical system that controls the probe current may be a diaphragm that adjusts the amount of passing electron beams. The probe current can be controlled by changing the hole diameter of the diaphragm (the size of the opening through which the electron beam passes). In this case, the history information 2 is information in which the probe current amount and the optical condition (that is, the hole diameter) of the diaphragm are associated with each other.

Further, the optical system for controlling the probe current may be a focusing lens 12 and an aperture. That is, the probe current may be controlled by both the focusing lens 12 and the aperture. In this case, the history information 2 is information in which the probe current amount is associated with the optical condition (exciting current) of the focusing lens 12 and the optical condition (hole diameter) of the diaphragm.

Further, in order to control the probe current, in addition to the focusing lens 12 and the diaphragm, optical conditions such as an acceleration voltage (voltage applied between the cathode and the anode of the electron gun 11) may be controlled. In this case, the history information 2 is information in which the probe current is associated with the optical conditions of the optical system (focusing lens or aperture) and the accelerating voltage.

According to this modification, the probe current can be easily and accurately set as in the above-described embodiment.

3.2. Second Modification Example In the above-described embodiment, a process of determining whether or not there is information on the probe current amount included in the history information 2 stored in the storage unit 54 that matches the target current amount ( Step S18) shown in FIG. 3 was performed. The process of step S18 is not limited to this, and may be determined according to the degree of coincidence between the probe current and the target current amount included in the history information 2.

For example, the process of step S20 may be performed when the error of the probe current included in the history information 2 with respect to the target current amount is less than a predetermined value, and the process of step S32 may be performed when the error is equal to or more than a predetermined value. As a result, even if the probe current amount included in the history information 2 and the target current amount do not completely match, if the error of the probe current included in the history information 2 with respect to the target current amount is small, the history information 2 The probe current can be set based on.

According to this modification, the probe current can be easily and accurately set as in the above-described embodiment.

3.3. Third Modified Example In the above-described embodiment, the irradiation target to which the electron beam is irradiated is the sample S, but the irradiation target is not limited to the sample S. For example, in the above-described embodiment, the electron probe microanalyzer has been described as an example of the charged particle beam device according to the present invention, but the charged particle beam device according to the present invention irradiates a sample with X-rays for analysis. It may be an analyzer (for example, an X-ray photoelectron spectrometer (XPS)). In such an analyzer, the X-ray source is configured to include an electron gun and an X-ray target, and the X-ray target is irradiated with the electron beam emitted from the electron gun to generate X-rays. In this case, the irradiation target is an X-ray target that generates X-rays by being irradiated with an electron beam.

Further, for example, the charged particle beam apparatus according to the present invention may be a processing apparatus such as an electron beam vapor deposition apparatus. For example, in an electron beam vapor deposition apparatus, an electron beam emitted from an electron gun is applied to an evaporative material, and the evaporative material is heated and evaporated to form a thin film on a film to be formed such as a substrate and a lens. In this case, the irradiation target is an evaporative material that evaporates when the electron beam is irradiated.

Further, for example, in the above-described embodiment and each modification, an electron beam has been described as an example of the charged particle beam irradiated to the irradiation target, but the charged particle beam irradiated to the irradiation target is limited to the electron beam. Instead, for example, it may be an ion or the like. That is, the charged particle beam device according to the present invention is not limited to a device equipped with an electron gun as a charged particle beam source, and may be, for example, a device equipped with an ion gun.

It should be noted that the above-described embodiments and modifications are merely examples, and the present invention is not limited thereto. For example, each embodiment and each modification can be combined as appropriate.

The present invention includes substantially the same configurations as those described in the embodiments (eg, configurations with the same function, method and result, or configurations with the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same effects as the configuration described in the embodiment or a configuration that can achieve the same object. The present invention also includes a configuration in which a known technique is added to the configuration described in the embodiment.

2 ... history information, 11 ... electron gun, 12 ... focusing lens, 13 ... deflector, 14 ... objective lens, 15 ... sample stage, 17 ... secondary electron detector, 18 ... energy dispersive X-ray detector, 19 ... Wavelength dispersive X-ray spectroscope, 19a ... Spectrometer, 19b ... X-ray detector, 20 ... Faraday cup, 22 ... Current meter, 30 ... Condenser drive device, 32 ... Fine adjustment circuit, 34 ... Coarse adjustment circuit , 36 ... Condenser power supply, 40 ... Processing unit, 50 ... Operation unit, 52 ... Display unit, 54 ... Storage unit, 100 ... Electronic probe microanalyzer

Claims (9)

Charged particle beam source and
An optical system that controls the irradiation amount of charged particle beams that irradiate the irradiation target,
An irradiation amount measuring unit that measures the irradiation amount of the charged particle beam irradiated to the irradiation target,
A storage unit that stores historical information associated with the irradiation amount of the charged particle beam and the optical conditions of the optical system.
A control unit that controls the optical system based on the history information and updates the history information based on the controlled optical conditions of the optical system.
Only including,
The control unit
The first process of determining whether or not there is an irradiation amount that matches the target irradiation amount from the irradiation amount information included in the history information, and
When it is determined that there is a match in the first process, the optical system is controlled based on the optical conditions of the optical system included in the history information and associated with the information of the matched irradiation dose. 2 processing and
A charged particle beam device that does . In claim 1,
The control unit
An error of the irradiation amount measured by the irradiation amount measuring unit with respect to the target irradiation amount is calculated, and when the error is less than a predetermined value, the target irradiation amount is stored in the storage unit in association with the optical conditions of the optical system. A charged particle beam device that updates the history information. In claim 1 or 2 ,
Includes an optical system drive unit that drives the optical system based on a control signal from the control unit.
The optical system drive unit
A first irradiation amount changing unit that changes the irradiation amount of the charged particle beam irradiated to the irradiation target in the first step width, and
The second step, in which the irradiation amount of the charged particle beam irradiated to the irradiation target is larger than the width of the first step.
The second irradiation amount change part that changes with the step width, and
Have,
The control unit
After the second treatment, a third treatment for acquiring information on the irradiation amount measured by the irradiation amount measuring unit, and
The fourth process of calculating the error of the irradiation amount measured by the irradiation amount measuring unit with respect to the target irradiation amount, and
The fifth process of controlling the first irradiation amount changing unit so that the irradiation amount becomes the target irradiation amount when the error is equal to or more than the first value and less than the second value.
The sixth process of controlling the second irradiation amount changing unit so that the irradiation amount becomes the target irradiation amount when the error is equal to or more than the second value.
A charged particle beam device that does. In claim 3 ,
The control unit
When the error is less than the first value, the seventh process of renewing the history information by associating the target irradiation amount with the optical conditions of the optical system in the second process and storing them in the storage unit. A charged particle beam device that does. In claim 3 or 4 ,
In the fifth process,
After controlling the first irradiation amount changing unit, a process of acquiring information on the irradiation amount measured by the irradiation amount measuring unit and calculating an error with respect to the target irradiation amount, and
The process of determining whether the error is greater than or equal to the predetermined value,
And
When it is determined that the error is equal to or more than a predetermined value, after controlling the first irradiation amount changing unit again, the irradiation amount information measured by the irradiation amount measuring unit is acquired and the error with respect to the target irradiation amount is calculated. And the process of determining whether the error is greater than or equal to the specified value.
A charged particle beam apparatus that performs an eighth process of deleting information on an irradiation amount that matches the target irradiation amount from the history information when the number of times these processes are repeated is a predetermined number of times or more. In any one of claims 3 to 5 ,
In the sixth process,
After controlling the second irradiation amount changing unit, a process of acquiring information on the irradiation amount measured by the irradiation amount measuring unit and calculating an error with respect to the target irradiation amount, and
The process of determining whether the error is greater than or equal to the predetermined value,
And
When it is determined that the error is equal to or more than a predetermined value, the error with respect to the target irradiation amount is calculated by acquiring the irradiation amount information measured by the irradiation amount measuring unit after controlling the second irradiation amount changing unit again. And the process of determining whether the error is greater than or equal to the specified value.
A charged particle beam apparatus that performs a ninth process of deleting information on an irradiation amount that matches the target irradiation amount from the history information when the number of times these processes are repeated is a predetermined number of times or more. In any one of claims 1 to 6 ,
The charged particle beam source is a charged particle beam device, which is a thermionic emission type electron gun. In any one of claims 1 to 7 ,
The irradiation target is a charged particle beam device that is an X-ray target that generates X-rays when a charged particle beam is irradiated. In any one of claims 1 to 7 ,
The irradiation target is a charged particle beam device, which is an evaporative material that evaporates when the charged particle beam is irradiated.

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