JP7090902B2 - Control method of focused ion beam device and focused ion beam device - Google Patents

Description

The present invention relates to a focused ion beam device and a method for controlling a focused ion beam device.

Conventionally, a focused ion beam device for processing a sample by irradiating the sample in the sample chamber with a focused ion beam (FIB) has been proposed (see, for example, Patent Document 1).
In the processing of the sample shape represented by the preparation of the TEM sample by the focused ion beam, there is a problem that the sample damage due to the ion beam irradiation is to be minimized. As a means for solving this problem, Patent Document 1 describes that roughing is performed at 30 kV and finishing is performed at 15 kV or less.
Further, in Patent Document 2, the energy of the ion beam used for the finishing process is 5 kV or less, which is lower than the energy of the ion beam used for the main process, and the angle of incidence on the sample is optimized according to the sample shape. It is stated that the damaged layer can be effectively removed.
As described above, it is known that processing is performed by lowering the acceleration voltage in order to suppress ion beam irradiation damage.

Japanese Unexamined Patent Publication No. 11-223588 JP-A-2007-193977 Japanese Unexamined Patent Publication No. 62-184754 Japanese Unexamined Patent Publication No. 2009-272293

The focused ion beam device as described above is divided into a plurality of machining steps such as rough machining, intermediate machining, and finishing machining, and machining is performed by an acceleration voltage according to the machining step. Here, the smaller the beam diameter of the focused ion beam irradiated on the sample, the better the processing accuracy. Therefore, in the focused ion beam device, it is desirable that the beam diameter of the focused ion beam can be controlled to be minimized. However, when processing is performed by lowering the acceleration voltage in order to suppress ion beam irradiation damage, "when the acceleration voltage is lowered and used, the amount of chromatic aberration increases and the ion beam cannot be sufficiently focused, so fine ions I can't get a probe. "
As a means for solving this problem, it is described that the acceleration lens operation and the deceleration lens operation are selectively acted according to the acceleration voltage so that the amount of chromatic aberration hardly changes.
Further, the same contents as described above are described in Patent Document 4.
Here, when the acceleration voltage of the focused beam is low, in addition to the increase in chromatic aberration, the influence of the interaction between ions (Coulomb interaction) becomes more remarkable than when the acceleration voltage is high. This Coulomb interaction increases the beam diameter of the focused ion beam.
However, according to the above-mentioned prior art, the influence on the beam diameter due to the Coulomb interaction is not taken into consideration, so that the beam diameter of the focused ion beam increases when the acceleration voltage is relatively low, for example, in finishing. There was a challenge.

The present invention has been made in view of the above circumstances, and provides a focused ion beam device and a focused ion beam device control method capable of reducing the influence of Coulomb interaction and controlling the beam diameter to be minimized. The purpose is to do.

One aspect of the present invention includes an ion source that emits ions, a condenser lens that focuses the ions emitted from the ion source, and an objective lens that focuses the ions focused by the condenser lens at the irradiation position of the sample table. , The variable aperture provided between the ion source and the condenser lens and having a variable aperture diameter, and the aperture diameter of the variable aperture are controlled based on the magnitude of the acceleration voltage applied to the ion source. It is a focused ion beam device including a throttle diameter control unit.

In the focused ion beam device of one aspect of the present invention, a second variable diaphragm provided between the condenser lens and the projection optical system and having a variable diaphragm diameter is further provided, and the diaphragm diameter control unit is the sample. The diaphragm diameter of the second variable diaphragm is controlled based on the diaphragm diameter of the ions focused on the irradiation position of the table.

In the focused ion beam device of one aspect of the present invention, the diaphragm diameter control unit controls the diaphragm diameter by making the diaphragm diameter of the second variable diaphragm smaller than the diaphragm diameter of the variable diaphragm.

In the focused ion beam device of one aspect of the present invention, the throttle diameter control unit controls the diaphragm diameter by changing the diaphragm diameter of the second variable diaphragm without changing the diaphragm diameter of the variable diaphragm. The diaphragm diameter is controlled by the second control of controlling the diaphragm diameter by changing both the diaphragm diameter of the variable diaphragm and the diaphragm diameter of the second variable diaphragm.

The focused ion beam device of one aspect of the present invention further includes an acceleration voltage control unit that controls the acceleration voltage applied to the ion source in a plurality of stages, and the aperture diameter control unit is the aperture diameter of the variable aperture. Is set to a throttle diameter according to the stage of the applied voltage controlled by the acceleration voltage control unit, and the throttle diameter is controlled.

One aspect of the present invention includes an ion source that emits ions, a condenser lens that focuses the ions emitted from the ion source, and an objective lens that focuses the ions focused by the condenser lens at the irradiation position of the sample table. The aperture diameter control of the focused ion beam device provided between the ion source and the condenser lens and having a variable aperture having a variable aperture diameter and an aperture diameter control unit for controlling the aperture diameter of the variable aperture. The unit is a control method of a focused ion beam device that controls the aperture diameter of the variable aperture based on the magnitude of the acceleration voltage applied to the ion source.

According to the present invention, it is possible to provide a focused ion beam device capable of reducing the influence of Coulomb interaction and controlling the beam diameter to be minimized.

It is a figure which shows the structural example of the focused ion beam apparatus which concerns on embodiment. It is a figure which shows an example of the functional structure of the control device of this embodiment. It is a figure which shows an example of the rough processing by the focused ion beam apparatus of this embodiment. It is a figure which shows an example of the intermediate processing by the focused ion beam apparatus of this embodiment. It is a figure which shows an example of the finishing process by the focused ion beam apparatus of this embodiment. It is a figure which shows an example of the set value of the acceleration voltage and the set value of a diaphragm diameter in each processing step of this embodiment.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. The configuration of the focused ion beam device 1 will be described with reference to FIG.

FIG. 1 is a diagram showing a configuration example of the focused ion beam device 1 according to the embodiment. In FIG. 1, the left-right direction of the focused ion beam device 1 is the x-axis direction, the depth direction is the y-axis direction, and the height direction is the z-axis direction.

The focused ion beam device 1 includes a sample chamber 11 capable of maintaining the inside in a vacuum state, a stage 12 (sample table) capable of fixing the sample S inside the sample chamber 11, and a drive mechanism 13 for driving the stage 12. There is. Further, the focused ion beam device 1 includes a focused ion beam lens barrel 14, a detector 15, a display device 16, a gas supply unit 17, and a control device 18.

The drive mechanism 13 is housed inside the sample chamber 11 in a state of being connected to the stage 12, and displaces the stage 12 with respect to a predetermined axis according to a control signal output from the control device 18. The drive mechanism 13 includes a moving mechanism 13a that moves the stage 12 in parallel along the x-axis and y-axis parallel to the horizontal plane and orthogonal to each other and the z-axis orthogonal to the x-axis and y-axis.
Further, the drive mechanism 13 includes a tilt mechanism 13b that rotates the stage 12 around the x-axis or the y-axis, and a rotation mechanism 13c that rotates the stage 12 around the z-axis.

The focused ion beam lens barrel 14 irradiates the sample S fixed to the stage 12 with the focused ion beam. The focused ion beam lens barrel 14 is fixed to the sample chamber 11 with the beam emitting portion 14A facing the stage 12 at a position above the stage 12 in the vertical direction and the optical axis parallel to the vertical direction inside the sample chamber 11. Has been done. As a result, the sample S fixed on the stage 12 can be irradiated with the focused ion beam in the vertical direction.
Further, the focused ion beam lens barrel 14 includes an ion source 14a and an ion optical system 14b.
The ion optical system 14b includes a first diaphragm 141, a condenser lens 14c, a beam blanking electrode 14d, a second diaphragm 142, an alignment 14f, an objective lens 14g, and a scanning electrode 14h.

The ion source 14a emits ions by the applied extraction voltage. In the ion source 14a and the ion optical system 14b, the irradiation position and irradiation conditions of the focused ion beam are controlled by the control device 18.

The condenser lens 14c focuses the ions radially emitted from the ion source into a beam shape. The control device 18 can adjust the magnitude of the lens action by controlling the applied voltage of the condenser lens 14c.

The beam blanking electrode 14d controls the irradiation of the ion beam focused by the condenser lens 14c onto the sample S according to the control of the control device 18. The beam blanking electrode 14d acts as a deflector. When irradiating the sample S with an ion beam, the beam blanking electrode 14d is not operated. When the irradiation of the ion beam onto the sample S is stopped, the beam blanking electrode 14d is operated to deflect the ion beam from the optical axis. As a result, the ion beam does not pass through the hole of the second diaphragm 142, is irradiated around the hole, and does not reach the sample S.

The alignment 14f corrects the trajectory of the ion beam that has passed through the second diaphragm 142 according to the control of the control device 18, and adjusts the ion beam so that it passes through the center of the objective lens 14g.

The objective lens 14g focuses the focused ion beam that has passed through the alignment 14f at a predetermined position on the sample S according to the control of the control device 18. That is, the objective lens 14g focuses the ions focused by the condenser lens 14c at the irradiation position of the stage 12 (sample table).

The scanning electrode 14h scans the ion beam that has passed through the objective lens 14g on the sample S under the control of the control device 18. The scanning electrode 14h may be arranged above the objective lens 14g.
Although not shown, an astigmatism corrector for adjusting the cross-sectional shape of the ion beam to a circular shape may be provided between the condenser lens 14c and the objective lens 14g.

The first diaphragm 141 and the second diaphragm 142 are variable diaphragms having a variable diaphragm diameter. The first diaphragm 141 and the second diaphragm 142 change the diaphragm diameter according to the control of the control device 18. The first diaphragm 141 and the second diaphragm 142 limit the current of the ion beam to a current value corresponding to the diaphragm diameter by changing the diaphragm diameter.
The first diaphragm 141 and the second diaphragm 142 may be composed of a plurality of diaphragms having different diameters, and the diaphragm diameter may be selected according to a desired beam current.

The first diaphragm 141 is arranged between the ion source 14a and the condenser lens 14c. That is, the first diaphragm 141 is provided between the ion source 14a and the condenser lens 14c, and the diaphragm diameter is variable.

The second diaphragm 142 is arranged between the condenser lens 14c and the objective lens 14g. That is, the second diaphragm 142 is provided between the condenser lens 14c and the objective lens 14g, and the diaphragm diameter is variable.

The detector 15 determines the intensity (amount of secondary charged particles) of the secondary charged particles (for example, secondary electrons and secondary ions) emitted from the sample S when the sample S is irradiated with the focused ion beam. Is detected, and information on the intensity of the detected secondary charged particle R is output. The detector 15 is arranged inside the sample chamber 11 at a position where the intensity of the secondary charged particles R can be detected, for example, a position diagonally above the sample S, and is fixed to the sample chamber 11.

The display device 16 displays image data or the like based on the secondary charged particles R detected by the detector 15.

The gas supply unit 17 has the gas injection unit 17a facing the stage 12 inside the sample chamber 11 and is fixed to the sample chamber 11. The gas supply unit 17 includes an etching gas G for selectively promoting etching of the sample S by the focused ion beam according to the material of the sample S, and a deposit of metal or an insulator on the surface of the sample S. A deposition gas G for forming a position film, and the like can be supplied to the sample S. For example, etching is selectively promoted by supplying etching gas G such as xenone fluoride for Si-based sample S and water for organic sample S to sample S together with irradiation of a focused ion beam. Let me. Further, for example, a solid decomposed from the deposition gas G by supplying the deposition gas G of the compound gas containing phenanthrene, platinum, carbon, tungsten or the like to the sample S together with the irradiation of the focused ion beam. The components are deposited on the surface of sample S.

The control device 18 is arranged outside the sample chamber 11 and includes an input unit 18a that outputs a signal corresponding to an input operation of the operator.
The control device 18 integrally controls the operation of the focused ion beam device 1 by a signal output from the input unit 18a, a signal generated by a preset automatic operation control process, or the like.
In the example shown in the figure, a device that irradiates a focused ion beam toward the vertical direction is shown, but the present invention is not limited to this, and the device may be configured to irradiate from an inclined direction or a horizontal direction.

FIG. 2 is a diagram showing an example of the functional configuration of the control device 18 of the present embodiment. The control device 18 includes an acceleration voltage control unit 181, a diaphragm diameter control unit 182, and a storage unit 183.

The acceleration voltage control unit 181 controls the acceleration voltage applied to the ion source 14a. The acceleration voltage control unit 181 of the present embodiment controls the acceleration voltage applied to the ion source 14a in a plurality of stages.
The diaphragm diameter control unit 182 controls the diaphragm diameter of the first diaphragm 141 based on the magnitude of the acceleration voltage applied to the ion source 14a. Further, the diaphragm diameter control unit 182 controls the diaphragm diameter of the second diaphragm 142 based on the focused diameter of the ions focused on the irradiation position of the stage 12.

Here, an example of the processing step of the sample S by the focused ion beam device 1 will be described with reference to FIGS. 3 to 6. In this example, the focused ion beam device 1 processes the sample S by three processing steps of rough processing, intermediate processing, and finishing processing.

[(1) Roughing step setting value]
FIG. 3 is a diagram showing an example of rough processing by the focused ion beam device 1 of the present embodiment. The ion beam IB10 emitted from the ion source 14a is focused by the first diaphragm 141 and focused by the condenser lens 14c (ion beam IB11). The ion beam IB11 focused by the condenser lens 14c is focused by the second diaphragm 142 (ion beam IB12) and focused by the objective lens 14g (ion beam IB13). The ion beam IB13 focused by the objective lens 14g irradiates the sample S.
Here, an example of the set value of the acceleration voltage and the set value of the throttle diameter in the roughing step will be described with reference to FIG.

FIG. 6 is a diagram showing an example of a set value of an acceleration voltage and a set value of a diaphragm diameter in each processing step of the present embodiment. In this example, in the roughing step, the acceleration voltage is 30 to 40 kV, the aperture diameter of the first aperture 141 (first aperture diameter) is 100 to 900 μm, and the aperture diameter of the second aperture 142 is 100 to 900 μm. It is set to 150 to 600 μm, respectively. As a result, the current of the ion beam IB11 (first IB current) becomes 10 to 100 nA, and the current of the ion beam IB12 (second IB current) becomes 1 to 60 nA.

[(2) Setting value of intermediate machining step]
FIG. 4 is a diagram showing an example of intermediate processing by the focused ion beam device 1 of the present embodiment. The ion beam IB20 emitted from the ion source 14a is focused by the first diaphragm 141 and focused by the condenser lens 14c (ion beam IB21). The ion beam IB21 focused by the condenser lens 14c is focused by the second diaphragm 142 (ion beam IB22) and focused by the objective lens 14g (ion beam IB23). The ion beam IB23 focused by the objective lens 14 g irradiates the sample S.
Here, an example of the set value of the acceleration voltage and the set value of the throttle diameter in the intermediate machining step will be described with reference to FIG.

In this example, in the intermediate processing step, the acceleration voltage is 30 to 40 kV, the aperture diameter of the first aperture 141 (first aperture diameter) is 100 to 900 μm, and the aperture diameter of the second aperture 142 is 100 to 900 μm. It is set to 30 to 150 μm, respectively. As a result, the current of the ion beam IB21 (first IB current) becomes 10 to 100 nA, and the current of the ion beam IB 22 (second IB current) becomes 0.1 to 1 nA.

In this example, the rough machining step and the medium machining step have the same acceleration voltage and the first throttle diameter, but have different second throttle diameters. Specifically, in the medium machining step, the second drawing diameter is smaller (that is, narrowed) than the drawing diameter in the rough machining step.

[(3) Setting value of finishing processing step]
FIG. 5 is a diagram showing an example of finishing by the focused ion beam device 1 of the present embodiment. The ion beam IB30 emitted from the ion source 14a is focused by the first diaphragm 141 and focused by the condenser lens 14c (ion beam IB31). The ion beam IB31 focused by the condenser lens 14c is focused by the second diaphragm 142 (ion beam IB32) and focused by the objective lens 14g (ion beam IB33). The ion beam IB33 focused by the objective lens 14 g irradiates the sample S.
Here, an example of the set value of the acceleration voltage and the set value of the throttle diameter in the finishing processing step will be described with reference to FIG.

In this example, in the finishing step, the acceleration voltage is 0.5 to 5 kV, the aperture diameter of the first aperture 141 (first aperture diameter) is 10 to 100 μm, and the aperture diameter of the second aperture 142 (second aperture diameter). ) Is set to 10 to 30 μm, respectively. As a result, the current of the ion beam IB31 (first IB current) becomes 5 to 20 pA, and the current of the ion beam IB 32 (second IB current) becomes 5 to 20 pA.

[Operation in each machining step]
Returning to FIG. 2, the storage unit 183 stores the set value information in each processing step shown in FIG. The acceleration voltage control unit 181 and the aperture diameter control unit 182 perform control based on the set value stored in the storage unit 183.

[(1) Operation in roughing step]
As an example, the operator of the focused ion beam device 1 operates the input unit 18a to instruct the control device 18 to perform "rough processing".
In this case, the aperture diameter control unit 182 reads out the set value of the roughing step among the set values of the first aperture diameter and the second aperture diameter stored in the storage unit 183. In this example, the aperture diameter control unit 182 reads out the set value (for example, 100 to 900 μm) of the roughing step among the set values of the first aperture diameter stored in the storage unit 183. The throttle diameter control unit 182 reads out the set value (for example, 150 to 600 μm) of the roughing step among the set values of the second throttle diameter stored in the storage unit 183. The aperture diameter control unit 182 controls the aperture diameter of the first aperture 141 to be 100 to 900 μm and the aperture diameter of the second aperture 142 to 150 to 600 μm based on the read set value.
Further, the acceleration voltage control unit 181 reads out the set value (for example, 30 to 40 kV) of the roughing step among the set values of the acceleration voltage stored in the storage unit 183. The acceleration voltage control unit 181 controls the focused ion beam device 1 to generate an acceleration voltage of 30 to 40 kV based on the read set value.

In this roughing step, the aperture diameter control unit 182 controls the aperture diameter by making the aperture diameter of the second aperture 142 smaller than the aperture diameter of the first aperture 141.

[(2) Operation in the intermediate machining step]
When the roughing of the sample S is completed, the operator of the focused ion beam device 1 operates the input unit 18a to instruct the control device 18 to perform "medium machining".
In this case, the aperture diameter control unit 182 has a set value of the intermediate processing step (for example, 100 to 900 μm for the first aperture 141) among the set values of the first aperture diameter and the second aperture diameter stored in the storage unit 183. , 30 to 150 μm for the second aperture 142) is read out. The aperture diameter control unit 182 controls the aperture diameter of the first aperture 141 to be 100 to 900 μm and the aperture diameter of the second aperture 142 to 30 to 150 μm based on the read set value.
Further, the acceleration voltage control unit 181 reads out the set value (for example, 30 to 40 kV) of the intermediate processing step among the set values of the acceleration voltage stored in the storage unit 183. The acceleration voltage control unit 181 controls the focused ion beam device 1 to generate an acceleration voltage of 30 to 40 kV based on the read set value.

In this intermediate processing step, the aperture diameter control unit 182 controls the aperture diameter by making the aperture diameter of the second aperture 142 smaller than the aperture diameter of the first aperture 141.

Further, when advancing the machining step from the rough machining step to the intermediate machining step, the throttle diameter control unit 182 changes the throttle diameter of the second throttle 142 without changing the throttle diameter of the first throttle 141 to change the diaphragm diameter. Control.

[(3) Operation in finishing step]
When the intermediate processing for the sample S is completed, the operator of the focused ion beam device 1 operates the input unit 18a to instruct the control device 18 to perform "finishing processing".
In this case, the aperture diameter control unit 182 has a set value of the finishing processing step (for example, 10 to 100 μm for the first aperture 141) among the set values of the first aperture diameter and the second aperture diameter stored in the storage unit 183. , 10 to 30 μm for the second aperture 142) is read out. The aperture diameter control unit 182 controls the aperture diameter of the first aperture 141 to be 10 to 100 μm and the aperture diameter of the second aperture 142 to be 10 to 30 μm based on the read set value.
Further, the acceleration voltage control unit 181 reads out the set value (for example, 0.5 to 5 kV) of the finishing processing step among the set values of the acceleration voltage stored in the storage unit 183. The acceleration voltage control unit 181 controls the focused ion beam device 1 to generate an acceleration voltage of 0.5 to 5 kV based on the read set value.

In this finishing step, the aperture diameter control unit 182 controls the aperture diameter by making the aperture diameter of the second aperture 142 smaller than the aperture diameter of the first aperture 141.
In the finishing step, the diaphragm diameter control unit 182 may control the diaphragm diameter by setting the diaphragm diameter of the first diaphragm 141 and the diaphragm diameter of the second diaphragm 142 to the same diameter (for example, 10 μm). good.

Further, when advancing the machining step from the intermediate machining step to the finishing machining step, the throttle diameter control unit 182 controls the throttle diameter by changing both the throttle diameter of the first throttle 141 and the throttle diameter of the second throttle 142. ..

Further, when advancing the machining step from the intermediate machining step to the finishing machining step, the throttle diameter control unit 182 is in the stage of the applied voltage in which the throttle diameters of the first throttle 141 and the second throttle 142 are controlled by the acceleration voltage control unit 181. The aperture diameter is controlled according to the aperture diameter.

[Summary of embodiments]
As described above, in the focused ion beam device 1, a first diaphragm 141 is provided between the ion source 14a and the condenser lens 14c. When the sample S is machined, the focused ion beam device 1 steps in the machining steps such as the roughing step, the intermediate machining step, and the finishing machining step to achieve both the speed and the accuracy of the machining. In the focused ion beam device 1 of the present embodiment, in each of these processing steps, the throttle diameter control unit 182 controls the throttle diameter of the first throttle 141 based on the magnitude of the acceleration voltage applied to the ion source 14a. ..

In the finishing processing step, low damage and high processing accuracy are required. Therefore, it is desirable that the ion beam irradiated to the sample S in the finishing step has a relatively low energy and a relatively small beam diameter. Therefore, in the finishing step, the acceleration voltage is lowered and the current of the ion beam is reduced to a small value.
Here, it is known that the velocity (energy) and orbit of focused ions are displaced by the interaction between ions constituting the ion beam (that is, Coulomb interaction). When the acceleration voltage is relatively low and the current of the ion beam is relatively large, the Coulomb interaction has a great influence on the determination of the beam diameter. Coulomb interaction is observed as three phenomena: space charge effect, orbital displacement effect, and Bersche effect. Of these, at least the orbital displacement effect and the Bersche effect cannot be corrected by optical correction using an objective lens or the like, so it is difficult to reduce the beam diameter when the influence of Coulomb interaction is large.
As an example for reducing the current of the ion beam to a small value, it is conceivable to provide a movable diaphragm between the condenser lens and the objective lens and narrow the diaphragm diameter of the movable diaphragm. However, according to this configuration, an ion beam having a relatively low acceleration voltage and a relatively large current flows between the condenser lens and the movable diaphragm. Therefore, according to such a configuration, the influence of the Coulomb interaction between the condenser lens and the movable diaphragm becomes large, and this influence remains in the ion beam passing through the movable diaphragm. Therefore, according to this conventional configuration, the ion beam passing through the objective lens is largely affected by the Coulomb interaction, which causes a problem that it is difficult to reduce the beam diameter.

In the focused ion beam device 1 of the present embodiment, the first diaphragm 141 is provided between the ion source 14a and the condenser lens 14c. According to the focused ion beam device 1 configured in this way, the current of the ion beam IB passing through the condenser lens 14c can be reduced to a small value in the finishing processing step. Therefore, according to the focused ion beam device 1, the ion beam IB passing through the condenser lens 14c is less affected by the Coulomb interaction. Therefore, according to the focused ion beam device 1 of the present embodiment, the beam diameter can be controlled relatively easily by the objective lens 14 g, so that the beam diameter at the irradiation position of the sample S can be reduced.

Further, in the focused ion beam device 1 of the present embodiment, a second diaphragm 142 is provided between the condenser lens 14c (irradiation optical system) and the objective lens 14g (projection optical system).
Here, in the rough machining step and the intermediate machining step, the acceleration voltage is relatively high. When the acceleration voltage is high, the above-mentioned Coulomb interaction has a relatively small effect on the beam diameter. On the other hand, in the roughing step and the intermediate machining step, it is desirable that the current of the ion beam IB is relatively large in order to increase the machining energy and the machining speed.
The focused ion beam device 1 of the present embodiment increases the current value of the ion beam IB passing through the condenser lens 14c by increasing the aperture diameter of the first aperture 141 in the rough processing step and the intermediate processing step. Further, the focused ion beam device 1 controls the current value of the ion beam IB passing through the objective lens 14g by controlling the diaphragm diameter of the second diaphragm 142. With this configuration, the focused ion beam device 1 supplies an ion beam IB having a high acceleration voltage and a large current value in the rough machining step and the intermediate machining step, and the acceleration voltage is low in the finishing machining step. An ion beam IB having a small current value is supplied. That is, according to the focused ion beam device 1 of the present embodiment, it is possible to achieve both processing with a high acceleration large current and processing with a low acceleration small current while reducing the influence of Coulomb interaction.

Further, in the focused ion beam device 1 of the present embodiment, the aperture diameter control unit 182 controls the aperture diameter by making the aperture diameter of the second aperture 142 smaller than the aperture diameter of the first aperture 141. According to the focused ion beam device 1 configured in this way, the beam diameter of the ion beam IB passing through the objective lens 14 g can be reduced, and the control of the beam diameter at the irradiation position of the sample S becomes relatively easy. be able to.

Further, in the focused ion beam device 1 of the present embodiment, the aperture diameter control unit 182 controls the aperture diameter by changing the aperture diameter of the second aperture 142 without changing the aperture diameter of the first aperture 141. The aperture diameter is controlled by the control and the second control in which the aperture diameter of the first aperture 141 and the aperture diameter of the second aperture 142 are both changed to control the aperture diameter. Here, the first control is, for example, a control for advancing the machining step from the rough machining step to the intermediate machining step. The second control is, for example, a control for advancing the machining step from the intermediate machining step to the finishing machining step. That is, the focused ion beam device 1 reduces the beam current without changing the acceleration voltage when advancing the machining step from the rough machining step to the medium machining step. Further, the focused ion beam device 1 reduces the acceleration voltage and the beam current when advancing the machining step from the intermediate machining step to the finishing machining step. According to the focused ion beam device 1 configured in this way, the acceleration voltage and the current value of the ion beam IB can be controlled to the states required in each processing step while reducing the influence of the Coulomb interaction.

Further, the focused ion beam device 1 of the present embodiment includes an acceleration voltage control unit 181, and the aperture diameter control unit 182 controls the aperture diameter of the first aperture 141 by the acceleration voltage control unit 181. The aperture diameter is controlled according to the stage of. The focused ion beam device 1 supplies an ion beam IB having a high acceleration voltage and a large current value in the rough machining step and the intermediate machining step, and supplies an ion beam IB having a low acceleration voltage and a small current value in the finishing machining step. Supply.
Further, in the focused ion beam device 1 of the present embodiment, the acceleration voltage control unit 181 controls the acceleration voltage applied to the ion source 14a in a plurality of stages. As an example, the acceleration voltage control unit 181 sets the acceleration voltage to the value of the first stage (for example, 30 to 40 kV) in the rough machining step and the intermediate machining step, and sets the acceleration voltage to the value of the second stage (for example, 30 to 40 kV) in the finishing machining step. For example, it is controlled to 0.5 to 5 kV). According to the focused ion beam device 1 configured in this way, it is possible to achieve both machining with a high acceleration large current and machining with a low acceleration small current while reducing the influence of Coulomb interaction.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment and may be appropriately modified without departing from the spirit of the present invention. can. In addition, the above-described embodiments can be appropriately combined without departing from the spirit of the present invention.

Each of the above-mentioned devices has a computer inside. The process of each process of each of the above-mentioned devices is stored in a computer-readable recording medium in the form of a program, and the process is performed by the computer reading and executing this program. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Further, the computer program may be distributed to the computer via a communication line, and the computer receiving the distribution may execute the program.

Further, the above program may be for realizing a part of the above-mentioned functions.
Further, a so-called difference file (difference program) may be used, which can realize the above-mentioned function in combination with a program already recorded in the computer system.

1 ... Focused ion beam device, 12 ... Stage, 14 ... Focused ion beam lens barrel, 14a ... Ion source, 14b ... Ion optical system, 14c ... Condenser lens (irradiation optical system), 14g ... Objective lens (projection optical system), 141 ... 1st aperture, 142 ... 2nd aperture, 18 ... control device, 181 ... acceleration voltage control unit, 182 ... aperture diameter control unit, 183 ... storage unit, IB ... ion beam

Claims (6)

An ion source that emits ions and
A condenser lens that focuses the ions emitted from the ion source, and
An objective lens that focuses the ions focused by the condenser lens to the irradiation position of the sample table, and
A variable diaphragm provided between the ion source and the condenser lens and having a variable diaphragm diameter,
A diaphragm diameter control unit that controls the diaphragm diameter of the variable diaphragm based on the magnitude of the acceleration voltage applied to the ion source.
Focused ion beam device equipped with. A second variable diaphragm, which is provided between the condenser lens and the projection optical system and has a variable diaphragm diameter, is further provided.
The focused ion beam device according to claim 1, wherein the diaphragm diameter control unit controls the diaphragm diameter of the second variable diaphragm based on the focused diameter of ions focused at the irradiation position of the sample table. The aperture diameter control unit is
The focused ion beam device according to claim 2, wherein the diaphragm diameter of the second variable diaphragm is made smaller than the diaphragm diameter of the variable diaphragm to control the diaphragm diameter. The aperture diameter control unit is
Either the first control that controls the aperture diameter by changing the aperture diameter of the second variable aperture without changing the aperture diameter of the variable aperture, or the aperture diameter of the variable aperture and the aperture diameter of the second variable aperture. The focused ion beam device according to claim 2 or 3, wherein the diaphragm diameter is controlled by the second control that controls the diaphragm diameter by changing the diaphragm diameter. It is further equipped with an acceleration voltage control unit that controls the acceleration voltage applied to the ion source in multiple stages.
The aperture diameter control unit is
The focusing according to any one of claims 2 to 4, wherein the diaphragm diameter of the variable diaphragm is set to a diaphragm diameter according to the stage of the applied voltage controlled by the acceleration voltage control unit, and the diaphragm diameter is controlled. Ion beam device. An ion source that emits ions, a condenser lens that focuses the ions emitted from the ion source, an objective lens that focuses the ions focused by the condenser lens at the irradiation position of the sample table, the ion source and the condenser. The aperture diameter control unit of a focused ion beam device including a variable aperture provided between the lens and a variable aperture diameter and an aperture diameter control unit for controlling the aperture diameter of the variable aperture is
A control method for a focused ion beam device that controls the diaphragm diameter of the variable diaphragm based on the magnitude of the acceleration voltage applied to the ion source.

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