WO2007040098A1

WO2007040098A1 - Charged particle beam equipment and method for irradiating charged particle beam

Info

Publication number: WO2007040098A1
Application number: PCT/JP2006/319069
Authority: WO
Inventors: Yasuhiko Sugiyama; Ryoji Hagiwara; Junichi Tashiro
Original assignee: Sii Nanotechnology Inc.
Priority date: 2005-10-03
Filing date: 2006-09-26
Publication date: 2007-04-12
Also published as: JP2007103107A

Abstract

Charged particle beam equipment for irradiating a charged particle beam stably with low energy while reducing the beam diameter by suppressing aberration of the charged particle beam, and its irradiation method. Charged particle beam equipment in which the quantity, energy and focusing of a charged particle beam can be regulated freely, and its irradiation method are also provided. The charged particle beam equipment (1) comprises a charged particle supply section (3) applied with an acceleration voltage E, a means (4) for deriving and accelerating a charged particle beam B, and a means (5) for focusing the charged particle beam B and irradiating an earthed sample surface S with the charged particle beam B thus focused. The accelerating means (4) and the focusing means (5) comprise bipotential lenses (8, 9). An exit side electrode (8c) and an incident side electrode (9a) are connected with an intermediate acceleration power supply (14) for applying a voltage having a polarity different from that of the charged particle beam B. An incident side electrode (8a) is connected with a deriving power supply (11) and an exit side electrode (9c) is earthed.

Description

Specification

Charged particle beam apparatus and charged particle beam irradiation method

Technical field

[0001] The present invention relates to a charged particle beam apparatus that irradiates and processes or observes a charged particle beam to a fine structure such as a new material, a semiconductor device, a photomask, an X-ray mask, a memory element, or a magnetic head. And a charged particle beam irradiation method. In particular, the present invention relates to a charged particle beam apparatus and a charged particle beam irradiation method when the energy of a charged particle beam reaching a sample is less than 20 keV.

Background art

[0002] Conventionally, as a TEM (transmission electron microscope) sample preparation and photomask correction, there has been proposed a method in which a charged particle beam is irradiated onto a target portion to perform processing using a charged particle beam apparatus. However, in recent years, damage to irradiated objects such as TEM samples and photomasks due to irradiation with charged particle beams has become a problem. That is, in the preparation of a TEM sample, defects in the crystal lattice of the sample, amorphous defects, etc. occur, leading to a decrease in TEM image quality. Further, in the correction of the photomask, there is a problem that the charged particles of the irradiated charged particle beam enter the quartz part and the transmittance of the quartz part decreases. While the damage to these irradiated objects can be improved by reducing the energy of the charged particle beam, the focusing lens aberration (mainly chromatic aberration) increases in inverse proportion to the energy of the charged particle beam. End up. For this reason, there is a problem that the charged particle beam cannot be focused to a predetermined beam diameter, so that high-precision machining cannot be performed. In order to deal with such problems, the following charged particle beam devices have been proposed.

That is, to an ion source, an aggregating lens for focusing a charged particle beam from the ion source on a sample, a deflecting unit for deflecting, a power source for applying a voltage to the sample, and a deflecting unit There has been proposed a charged particle beam apparatus provided with means for controlling the intensity of the deflection signal according to the voltage applied to the sample (see, for example, Patent Document 1). According to such a charged particle beam apparatus, the energy of the charged particle beam is increased and the focusing lens is increased. It is said that the damage of the sample can be suppressed by reducing the energy of the charged particle beam by the voltage applied to the sample.

[0004] Further, an auxiliary electrode having the same potential as that of the sample is disposed between the focusing lens and the sample, and the gas nozzle force that can blow out the active gas through the minute opening is disposed between the sample and the auxiliary electrode. A charged particle beam apparatus has been proposed (see, for example, Patent Document 2). According to such a charged particle beam apparatus, the energy of the charged particle beam can be reduced by the voltage applied to the auxiliary electrode, and an electric field can be generated between the sample and the auxiliary electrode. It is said that gas-assisted etching can be performed while preventing discharge accompanying the supply of active gas.

[0005] In addition, the charged particle beam device that holds the sample at the ground potential and sets the extraction voltage to a value having a polarity opposite to that of the acceleration voltage, and extracts and irradiates the ion source charged particle beam by the potential difference. There has been proposed a charged particle beam apparatus including a high voltage tube that is applied to the same potential and allows a charged particle beam to pass through, and a shield tube that shields the high voltage tube from the high voltage tube at a predetermined interval. (For example, see Patent Document 3). In such a charged particle beam apparatus, it is supposed that a sample can be irradiated with a low-energy charged particle beam with the sample at ground potential without scattering the charged particle beam.

Patent Document 1: Japanese Patent Laid-Open No. 3-26105

Patent Document 2: JP-A-64-19667

Patent Document 3: JP-A-5-28947

Disclosure of the invention

Problems to be solved by the invention

[0006] However, in Patent Document 1, since a concave lens is formed by a decelerating electric field between the focusing lens and the sample, the discharge depends on the sample shape, and the sample is damaged or worn. There was a risk of device failure. In addition, when the sample is an insulator, a charge is induced on the sample surface by the electric field, and the surface potential becomes unstable due to charge injection and secondary electron emission due to irradiation of the charged particle beam. For this reason, there is a problem that the charged particle beam is affected by the potential change, and the irradiation point is not determined and high-precision machining cannot be performed. [0007] Also, in Patent Document 2, it is possible to prevent the above-mentioned discharge by making an electric field between the electrode and the sample, but in order to apply the sample to a high voltage, It doesn't change. Since the sample is exchanged using the transfer arm or robot arm, the applied voltage of the gas nozzle, auxiliary electrode, detector, etc. applied to the same voltage as the sample and the sample is released each time. It was necessary to apply voltage to the same potential again!]. And even if there is insulation degradation at one place, there is a possibility of discharging, which is problematic in terms of reliability.

[0008] Further, in Patent Document 3, it is possible to solve these problems by setting the sample to the ground potential, but an electric field exists between the focusing lens and the shield tube, and parasitic lens action occurs. End up. For this reason, there has been a problem that the optical axis shift due to the manufacturing accuracy occurs and the beam diameter increases due to off-axis aberration. In addition, since the extraction electrode and the focusing lens are at the same potential, changing the extraction voltage to adjust the amount of the charged particle beam extracted from the ion source also affects the trajectory of the charged particle beam. There was a problem.

[0009] The present invention has been made in view of the above-described circumstances, and can suppress the aberration of the charged particle beam, reduce the beam diameter, and stably irradiate the charged particle beam with low energy. A charged particle beam apparatus and a charged particle beam irradiation method are provided. In addition, a charged particle beam apparatus and a charged particle irradiation method capable of freely adjusting the amount and energy of the charged particle beam and the focusing of the charged particle beam are provided.

In order to solve the above problems, the present invention proposes the following means.

The present invention includes a charged particle supply unit that emits and irradiates a charged particle beam to a grounded sample surface, an acceleration power source that is connected to the charged particle supply unit and applies an acceleration voltage, and the charged particle supply A charged particle beam apparatus comprising: acceleration means for extracting and accelerating the charged particle beam from a portion; and focusing means for focusing the charged particle beam accelerated by the acceleration means and irradiating the sample surface. Each of the accelerating means and the converging means can apply at least one voltage of the incident side electrode, the intermediate electrode, and the emission side electrode. Prepared Each of the exit side electrode of the bipotential lens of the acceleration means and the entrance side electrode of the bipotential lens of the focusing means is connected to an intermediate acceleration power source that applies a voltage having a polarity different from the polarity of the charged particle beam. The incident-side electrode of the bipotential lens of the accelerating means is connected to a bow I power supply for applying a voltage to the incident-side electrode, and the emission-side electrode of the bipotential lens of the focusing means is grounded. Yes.

According to the charged particle beam apparatus of the present invention, the acceleration means and the focusing means are provided with a bipotential lens, and the potential difference between the acceleration voltage and the voltage applied to the emission side electrode of the bipotential lens (the emission side electrode) In addition to accelerating and decelerating the charged particle beam depending on the potential, the charged particle beam can be bundled by the electric field formed by the three electrodes, the entrance electrode, the intermediate electrode, and the exit electrode. In addition, the bipotential lens has a potential difference between the acceleration voltage and the voltage applied to the incident side electrode (potential of the incident side electrode), and a potential difference between the acceleration voltage and the voltage applied to the output side electrode (of the output side electrode). As the ratio to (potential) increases, the charged particle beam aberration can be reduced. In other words, the charged particle beam can be accelerated or decelerated, focused effectively, and irradiated with a reduced beam diameter.

For this reason, the charged particle beam is extracted from the charged particle supply unit by the potential of the incident side electrode of the bipotential lens of the accelerating means. The aberration is suppressed to a small value and accelerated to a high energy state due to the relationship between the potential of the incident side electrode and the potential of the output side electrode connected to the intermediate acceleration power source. Next, the potential of the grounded exit-side electrode is incident on the entrance-side electrode of the focusing device's bi-potential lens, which is at the same potential as the exit-side electrode of the acceleration means's bi-potential lens, at a constant velocity while maintaining a high energy state. As a result, the charged particle beam is effectively focused and irradiated onto the sample with a small beam diameter. In addition, the output side electrode of the bipotential lens of the focusing means and the sample are grounded to each other and are free of an electric field. For this reason, the charged particle beam can be stably irradiated onto the sample without fear of discharge or the like.

[0014] Further, as described above, the incident side electrode of the bipotential lens of the acceleration means is pulled out. Connected to a power source, the output side electrode is connected to an intermediate acceleration power source. For this reason, the voltage of the incident side electrode can be set by the extraction power supply so that the amount of the charged particle beam extracted from the charged particle supply unit is optimized. In order to effectively focus the charged particle beam as a high-energy state, the intermediate acceleration power supplies the voltages of the exit side electrode of the acceleration lens and the entrance side electrode of the bipotential lens of the focusing unit. Can be set. Furthermore, by using an acceleration means and a focusing means as a bipotential lens, an electric field can be created between these bipotential lenses and between the bipotential lens of the focusing means and the sample. Parasitic lens action does not occur. In Patent Document 3, off-axis aberration caused by the assembly accuracy of the parasitic lens due to the electric field between the focusing lens and the shield tube becomes a problem. On the other hand, in the structure according to the present invention, it is possible to suppress the occurrence of off-axis aberrations by ensuring the assembly accuracy of the centrality and inclination of the three electrodes of the bipotential lens shown in FIG. As a result, the aberration of the entire ion beam optical system can be suppressed.

[0015] In the above charged particle beam device, the intermediate electrode of the bipotential lens of the accelerating unit is connected to a condenser lens power source that applies a voltage having a polarity different from the polarity of the charged particle beam to the intermediate electrode. In addition, the intermediate electrode of the bipotential lens of the focusing means is more preferably connected to an objective lens power source that applies a voltage having a polarity different from the polarity of the charged particle beam to the intermediate electrode. ! /

According to the charged particle beam apparatus according to the present invention, the intermediate electrodes of the bipotential lenses of the accelerating unit and the focusing unit are connected to the condenser lens power source and the objective lens power source, respectively. Can be set. Then, by setting the polarity of the voltage to be applied to a polarity different from the polarity of the charged particle beam, the charged particle beam is accelerated in the intermediate electrode, and the aberration can be further reduced. It can be focused effectively.

[0017] Further, the present invention provides a charged particle beam irradiation that irradiates a sample surface with a charged particle beam that is extracted from a charged particle supply unit to which an acceleration voltage is applied by a potential difference from the acceleration voltage. A method comprising: an acceleration step for accelerating the charged particle beam; and a focusing step for focusing the charged particle beam. It is possible to apply different voltages to the pole, the intermediate electrode, and the output electrode, and a first neuropotential lens in which three electrodes are arranged in parallel is arranged, and the incident electrode of the first bipotential lens is arranged. A voltage is applied to the first bipotential lens to draw out the charged particle beam according to a potential difference from the acceleration voltage, and to enter the first bipotential lens. A voltage having a polarity different from the polarity of the charged particle beam is applied to suppress the charged particle beam convergence by the electric field formed by the incident side electrode, the intermediate electrode, and the emission side electrode, and the acceleration. The charged particle beam is accelerated by a potential difference between a voltage and a voltage applied to the emission-side electrode; By placing an equipotential lens and making the voltage of the incident side electrode equal to the output side electrode of the first bipotential lens, the incident electrode is made incident at the same speed, and the polarity of the charged particle beam is applied to the intermediate electrode. A voltage of different polarity is applied, the output side electrode is grounded, and the electric field formed by the incident side electrode, the intermediate electrode, and the output side electrode is decelerated by the potential difference between the calovelocity voltage and the grounded output side electrode. It is characterized by irradiating a grounded sample surface by focusing a charged particle beam by the above method.

According to the charged particle beam irradiation method of the present invention, the potential difference between the acceleration voltage and the voltage applied to the incident electrode of the first bipotential lens (according to the incident side electrode) during the acceleration step. Depending on the potential), the charged particle beam can be extracted in an optimal amount. Then, by applying a voltage having a polarity different from the polarity of the charged particle beam to each of the intermediate electrode and the emission side electrode, the charged particle beam can be brought into a high energy state by accelerating while suppressing aberrations small. Next, in the focusing step, the incident side electrode of the second bipotential lens is made equipotential with the output side electrode of the first bipotential lens, and a voltage having a polarity different from that of the charged particle beam is applied to the intermediate electrode. The charged particle beam in a high energy state is decelerated to a low energy state by focusing and the focused electrode surface is irradiated with the charged particle beam. Can do.

The invention's effect

According to the charged particle beam apparatus and the charged particle beam irradiation method of the present invention, the acceleration Bipotential lenses are arranged in the process and focusing process. Therefore, the amount and energy of the charged particle beam to be irradiated and the focusing of the charged particle beam can be adjusted freely.

It is possible to stably irradiate a grounded sample. In addition, the charged particle beam applied to the sample can be reduced in energy, the aberration can be suppressed, and the beam diameter can be reduced. Therefore, it is possible to process the sample with high accuracy while minimizing the damage to the sample caused by irradiation with the charged particle beam.

Brief Description of Drawings

FIG. 1 is a configuration diagram of an ion beam apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a bipotential lens according to an embodiment of the present invention.

FIG. 3 is a schematic view of a bipotential lens according to an embodiment of the present invention.

FIG. 4 is a graph showing characteristics of a bipotential lens according to an embodiment of the present invention. Explanation of symbols

[0021] 1 Ion beam device (charged particle beam device)

3 Ion supply unit (charged particle supply unit)

4 Acceleration means

5 Focusing means

7 Acceleration power supply

8 First bipotential lens

8a Incident side electrode

8b Intermediate electrode

8c Output side electrode

9 Second bipotential lens

9a Incident side electrode

9b Intermediate electrode

9c Output side electrode

11 Drawer power supply

12 Condenser lens power supply

14 Intermediate acceleration power supply 15 Objective lens power supply

B ion beam (charged particle beam)

E Acceleration voltage

P sample

S Sample surface

BEST MODE FOR CARRYING OUT THE INVENTION

[0022] (First embodiment)

1 to 4 show an embodiment according to the present invention. Figure 1 shows the configuration of the charged particle beam system. Fig. 2 is a cross-sectional view of the bipotential lens, Fig. 3 is a schematic diagram of the bipotential lens, and Fig. 4 is a graph showing the characteristics of the bipotential lens.

As shown in FIG. 1, an ion beam device 1 (charged particle beam device) irradiates a sample placement unit 2 for placing a sample P and a surface of the sample P (hereinafter referred to as sample surface S). The ion supply unit 3 (charged particle supply unit) for supplying the ion beam B (charged particle beam), the acceleration unit 4 for accelerating the ion beam B from the ion supply unit 3 force, and the acceleration unit 4 And a focusing means 5 for decelerating and focusing the ion beam B. The sample P is, for example, a photomask in photolithography. In addition, as shown in FIG. 1, the sample P is placed in the sample installation part 2 and is in a grounded state.

As shown in FIG. 1, the ion supply unit 3 includes an ion source 6. The ion source 6 is, for example, liquid gallium, is provided with a filament (not shown), and is connected to the filament power source 6a. For this reason, the ion source 6 is always kept in a liquid state by being heated by the filament, and is capable of emitting gallium ions (Ga +) as the ion beam B by a potential difference generated in the periphery. Further, an acceleration power source 7 capable of adjusting the voltage is connected to the ion supply unit 3, and a positive acceleration voltage E is applied thereto.

The acceleration means 4 and the focusing means 5 are provided with a first Neupotential lens 8 and a second bipotential lens 9, respectively. As shown in FIG. 2, the first bipotential lens 8 and the second bipotential lens 9 are insulated from the incident side electrodes 8a and 9a, the intermediate electrodes 8b and 9b, and the output side electrodes 8c and 9c, respectively. In parallel with the insulator 10 being electrically insulated, different voltages can be applied. Is possible. The incident-side electrodes 8a and 9a, the intermediate electrodes 8b and 9b, and the emission-side electrodes 8c and 9c are formed with through-holes 8d and 9d that pass through coaxially so that the incident ion beam B can pass therethrough. And

Here, as shown in FIG. 3, the potentials of the incident-side electrodes 8a and 9a of these bipotential lenses are VI, the potentials of the intermediate electrodes 8b and 9b are V2, and the potentials of the emission-side electrodes 8c and 9c are V3. The potential is determined by the potential = acceleration voltage E−lens voltage by the acceleration voltage E and the lens voltage applied to each electrode. An electric field can be formed between the incident side electrodes 8a and 9a, the intermediate electrodes 8b and 9b, and the output side electrodes 8c and 9c. The ion beam B penetrating through the through holes 8d and 9d can be focused by the formed electric field. Further, the ion beam B penetrating through the through holes 8d and 9d is accelerated (decelerated) by the incident speed due to the difference between the potential VI of the incident side electrodes 8a and 9a and the potential V3 of the emission side electrodes 8c and 9c. In other words, the ion beam B, which is a positive ion (Ga +) incident on the bipotential lens, is emitted at a reduced speed from the incident speed when VI> V3, and from the incident speed when V3 <V1. Accelerated and emitted. Furthermore, as shown in FIG. 4, as the ratio V1ZV3 of the potential VI of the incident side electrodes 8a and 9a and the potential V3 of the outgoing side electrodes 8c and 9c increases, the image plane S1 (for example, as shown in FIG. 3). Both the chromatic aberration coefficient Cc and the spherical aberration coefficient Cs at the surface 15 mm away from the emission-side electrodes 8c and 9c) are both small. In the case of an objective lens (focusing means 5), use it under the condition of V1> V3. 3 and 4 are explanatory diagrams of the objective lens (focusing means 5), but the same can be considered for the condenser lens (acceleration means 4). The image plane S1 is replaced with the object plane (ion source 6) by inverting the top and bottom of Fig. 3. The symbol representing the potential of each electrode is left as it is. The trajectory of the ion beam B runs in the opposite direction to the objective lens (focusing means 5). Due to the reciprocity of the orbit, the aberration coefficient at the object surface is as shown in Fig.4. In order to reduce the aberration on the image surface S1, it is necessary to reduce the aberration on the object surface. Therefore, aberrations can be minimized by using a condenser lens under the condition of VI> V3.

[0027] In other words, in the bipotential lens, the incident ion beam B is further accelerated (decelerated) by increasing the difference between the potential VI and the potential V3. In addition, by increasing the ratio of potential VI to potential V3, the ion beam B can be effectively focused and emitted with reduced aberration. Furthermore, the bipotential lens has the same polarity as the acceleration mode in which the intermediate electrodes 8b and 9b have a polarity different from the polarity of the ion beam B (a cathode when the ion beam B is a gallium ion (anode)). There is a deceleration mode. By setting the bipotential lens to the acceleration mode, the ion beam B aberration can be further reduced.

As shown in FIG. 1, the incident side electrode 8a of the first bipotential lens 8 is connected to the cathode of the extraction power source 11 capable of adjusting the voltage. In addition, the anode of the extraction power source 11 is connected to the anode of the acceleration power source 7 so that the voltage of the incident side electrode 8a of the first bipotential lens 8 is relatively lower than the voltage of the ion supply unit 3. It can be. Further, the intermediate electrode 8b is connected to the cathode of the condenser lens power source 12 capable of adjusting the voltage, and a negative voltage having a polarity different from that of the ion beam B (anode) is applied. Furthermore, the exit side electrode 8c of the first bipotential lens 8 and the entrance side electrode 9a of the second bipotential lens 9 are connected by an intermediate acceleration tube 13 having conductivity, and the intermediate acceleration tube 13 is connected to the cathode of the intermediate acceleration power source 14 capable of adjusting the voltage. For this reason, the inside of the exit side electrode 8c of the first bipotential lens 8, the entrance side electrode 9a of the second bipotential lens 9 and the intermediate acceleration power source 14 has a polarity different from the polarity (anode) of the ion beam B. A certain negative voltage is applied equally. Also, the intermediate electrode 9b of the second bipotential lens 9 is connected to the cathode of the objective lens power supply 15 capable of adjusting the voltage, and a negative voltage having a polarity different from that of the ion beam B (anode) is applied. It has been. Furthermore, the output-side electrode 9c is grounded, and an electric field is not formed between the same and the grounded sample P.

In addition, as shown in FIG. 1, the ion beam apparatus 1 further includes a blanking electrode 16 that performs ONZOFF of the irradiated ion beam B and an optical axis of the ion beam B inside the intermediate accelerator tube 13. Alignment electrode 17 for correcting the deviation, and astigmatism corrector 18 that corrects the distortion of the cross-sectional shape of ion beam B and forms a perfect circle. The blanking electrode 16 is connected to a blanking power source 19 and can apply a voltage to deflect the passing ion beam B so that the sample P is not irradiated. The alignment electrode 17 is The optical axis of the ion beam B that passes through can be corrected by connecting a voltage source 20 and applying an electric voltage to form an electric field. Further, the astigmatism corrector 18 is connected to the astigmatism correction power source 21 and applies a voltage to form an electric field, thereby correcting the distortion of the cross-sectional shape of the passing ion beam B. In addition, the ion beam apparatus 1 includes a scanning electrode 22 between the second bipotential lens 9 and the sample P. The scanning electrode 22 is connected to the scanning power source 23, and the position of the ion beam B passing through the sample surface S can be adjusted by operating the voltage of the scanning power source 23.

[0030] Although not shown, a gas gun that discharges an assist gas to a processing position on the sample surface S, or a secondary electron detector that detects secondary electrons generated when the sample surface S is irradiated with the ion beam B Or a secondary ion detector for detecting secondary ions may be provided near the sample surface S. By selectively supplying the assist gas to the processing position of the sample surface S with a gas gun, the sample surface S can be effectively etched or deposited. Further, the state of the sample surface S irradiated with the ion beam B can be observed by a secondary electron detector or a secondary ion detector. These gas guns, secondary electron detectors, secondary ion detectors, and the like can be provided in an equipotential environment in which the output electrode 9c of the sample P and the second bipotential lens 9 is grounded. Therefore, it can be operated without the need for insulation treatment.

Next, the operation of the ion beam apparatus 1 will be described. As shown in FIG. 1, gallium as the ion source 6 of the ion supply unit 3 is always kept in a liquid state by a filament (not shown). Then, the acceleration voltage E of +10 kV is applied to the ion supply unit 3 because the voltage of the acceleration power source 7 is set to 10 kV, for example. In addition, since the extraction power supply 11 is set to a voltage of 6 kV, for example, a voltage of +4 kV is applied to the incident side electrode 8a of the first bipotential lens 8. That is, a potential difference of 6 kV (potential of the incident side electrode 8a) is generated by the acceleration voltage E and the voltage applied to the incident side electrode 8a of the first bipotential lens 8. The potential of the incident side electrode 8a is caused by this potential. The liquid gallium as the ion source 6 is extracted from the ion supply unit 3 as gallium ions (Ga +), and is incident on the first bipotential lens 8 as the acceleration means 4 as the ion beam B. In addition, the condenser lens power supply 12 is set to a voltage of 20 kV, for example, and the intermediate acceleration power supply 14 is set to a voltage of 10 kV, for example. For this reason, the intermediate electrode 8b of the first bipotential lens 8 is applied to a voltage of 20 kV and the output-side electrode 8c is applied to a voltage of −10 kV, so that the potential of the output-side electrode 8c is 20 kV. Therefore, in the first bipolar potential lens 8, the ratio VlZV3 (20Z6 = 3.3) between the potential of the incident side electrode 8a and the potential of the outgoing side electrode 8c is set to a large value, and the intermediate electrode 8b is negatively charged. By adopting the acceleration mode to which voltage is applied, the incident ion beam B is suppressed to a small aberration and accelerated to 20 keV by the potential of the emission side electrode 8c to be in a high energy state.

Next, the ion beam B accelerated by the first bipotential lens 8 passes through the interior of the intermediate acceleration tube 13, which is equipotential, to the second bipotential lens 9 at a constant speed. At this time, the blanking electrode 16 is turned ON / OFF as necessary, the optical axis is corrected by the alignment electrode 17, the cross-sectional distortion is corrected by the astigmatism corrector 18, and the second bipotential lens 9 is corrected. Incident. Here, the objective lens power supply 15 is set to a voltage of 2 OkV, for example. For this reason, the intermediate electrode 9b of the second bipotential lens 9 is applied to a voltage of 20 kV. Also, since the output side electrode 9c is grounded, it is OkV. That is, in the second bipotential lens 9, the potential of the incident side electrode 9a is 20 kV, the potential of the output side electrode 9c is 10 kV, and the ratio between the potential of the incident side electrode 9a and the potential of the output side electrode 9c V1ZV3 (20/10 = 2) can be increased. For this reason, the ion beam B incident on the second bipotential lens 9 is decelerated to 10 kV by the potential of the emission side electrode 9c, and is formed by the incidence side electrode 9a, the intermediate electrode 9b, and the emission side electrode 9c. By this electric field, the light is effectively focused and emitted with small aberration. For this reason, the ion beam B focused by the second bipotential lens 9 is irradiated on the sample surface S with a small beam diameter and in a low energy state. In addition, since the output electrode 9c of the second bipotential lens 9 and the sample P are grounded and have no electric field, the ion beam B is stable without being affected by the electric field. The scanning electrode 22 is scanned so as to irradiate a predetermined processing position, and the sample surface S is irradiated. As described above, in the ion beam apparatus 1 of the present embodiment, the characteristics of the two bipotential lenses of the first bipotential lens 8 in the acceleration unit 4 and the second bipotential lens 9 in the focusing unit 5 are determined. By accelerating to a high energy state and then decelerating, the aberration can be reduced and focused effectively, and the beam diameter can be reduced. In addition, by accelerating and decelerating with two bipotential lenses, the ion beam B is finally irradiated on the sample surface S as a low energy state only by the energy by the acceleration voltage E applied by the acceleration power source 7. For this reason, the damage of the irradiated sample P can be minimized and the sample P can be processed with high accuracy.

[0035] Note that the setting of the voltage of each power supply is not limited to that described above, and the voltage can be set according to the performance of each power supply. Therefore, the acceleration power supply 7 connected to the ion supply unit 3 can set the voltage so that the energy of the ion beam B when the sample P is irradiated is optimized. Further, the voltage of the extraction power source 11 can be set so that the amount of the ion beam B extracted from the ion source 6 is optimum. Further, the voltage of the intermediate accelerating power source 14 varies between the potential VI of the incident side electrodes 8a and 9a in the first bipotential lens 8 and the second bipotential lens 9 and the potential V3 of the output side electrodes 8c and 9c. The ratio can be increased and the aberration can be decreased. In addition, stable irradiation of the ion beam B can be realized by keeping the emission-side electrode 9c of the second bipolar potential lens 9 and the sample P in contact with each other regardless of other electrodes. In other words, the acceleration means 4 and the focusing means 5 are each provided with a bipotential lens, so that the amount and energy of the ion beam B to be irradiated and the bundle of the ion beam B can be freely adjusted and stably irradiated. it can. In addition, there can be no electric field between the first bipotential lens 8 and the second bipotential lens 9 and between the second bipotential lens 9 and the sample P. Parasitic lens action like this does not occur. For this reason, the occurrence of off-axis aberration can be suppressed by ensuring the assembly accuracy of each electrode of each bipotential lens. As a result, it is possible to reduce the aberration of the entire ion beam optical system.

[0036] As described above, 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. Is also included.

[0037] It should be noted that the force using the sample P processed in the ion beam apparatus 1 as a photomask is not limited to this. For example, the ion beam apparatus 1 may be used to process a sample into a thin piece so that the sample can be observed with a TEM. Moreover, since the sample P is in a grounded state, it may be an insulator. The ion source 6 of the ion supply unit 3 is liquid gallium, and is not limited to the force that uses the ion beam B as the gallium ion (Ga +). The ion source 6 is not limited to a liquid but may be a solid or gas, or may be an anion. For example, the ion source 6 may be an ion source using rare gas (Ar) or alkali metal (Cs) as an ion species. Furthermore, it is not limited to an ion beam, but may be a charged particle beam that is a charged particle such as an electron beam. However, in the case of negatively charged particles such as an ion beam or an electron beam due to negative ions, it is necessary to reverse the polarity of the voltage applied to each in the above-described embodiment.

Further, the force that the acceleration means 4 is provided with the first bipotential lens 8 and the focusing means 5 is provided with the second bipotential lens 9 is not limited to this. As long as at least one bipotential lens is provided in each of the acceleration means 4 and the focusing means 5, a configuration in which a plurality of bipotential lenses are provided may be employed.

Industrial applicability

[0039] The charged particle beam applied to the sample can be reduced in energy, the aberration can be suppressed, and the beam diameter can be reduced. For this reason, it is possible to minimize damage to the sample accompanying irradiation of the charged particle beam and to process the sample with high accuracy.

Claims

The scope of the claims

[1] A charged particle supply unit that emits and irradiates a charged particle beam to a grounded sample surface; an acceleration power source that is connected to the charged particle supply unit and applies an acceleration voltage;

A charged particle beam apparatus comprising: acceleration means for extracting and accelerating the charged particle beam from the charged particle supply unit; and focusing means for focusing the charged particle beam accelerated by the acceleration means and irradiating the sample surface Because

Each of the accelerating means and the focusing means includes at least one bipotential lens in which three electrodes that can apply different voltages of the incident side electrode, the intermediate electrode, and the output side electrode are arranged in parallel,

Each of the exit-side electrode of the bipotential lens of the acceleration means and the entrance-side electrode of the bipotential lens of the focusing means is connected to an intermediate acceleration power source that applies a voltage having a polarity different from the polarity of the charged particle beam. ,

The incident side electrode of the bipotential lens of the accelerating means is connected to an extraction power source that applies a voltage to the incident side electrode;

The charged particle beam device according to claim 1, wherein the output side electrode of the bipotential lens of the focusing means is grounded.

[2] The charged particle beam apparatus according to claim 1, wherein

The intermediate electrode of the bipotential lens of the accelerating means is connected to a condenser lens power source that applies a voltage having a polarity different from the polarity of the charged particle beam to the intermediate electrode.

The charged particle beam apparatus characterized in that the intermediate electrode of the bipotential lens of the focusing means is connected to an objective lens power source that applies a voltage having a polarity different from that of the charged particle beam to the intermediate electrode.

[3] A charged particle beam irradiation method in which a charged particle beam is extracted from a charged particle supply unit to which an acceleration voltage is applied by a potential difference from the acceleration voltage, and is accelerated to a sample surface,

Accelerating step of accelerating the charged particle beam and focusing the charged particle beam A focusing process,

In the acceleration step, it is possible to apply different voltages to the incident side electrode, the intermediate electrode, and the emission side electrode. A voltage is applied to the incident side electrode of the lens, and the charged particle beam is drawn out by a potential difference from the acceleration voltage, is incident on the first bipotential lens, and the intermediate electrode of the first bipotential lens. A voltage having a polarity different from that of the charged particle beam is applied to each of the emission side electrode and the charged particle beam aberration is suppressed by an electric field formed by the incidence side electrode, the intermediate electrode, and the emission side electrode. Accelerating the charged particle beam by a potential difference between the acceleration voltage and a voltage applied to the emission-side electrode, In the focusing step, a second neutral potential lens is arranged and the voltage of the incident side electrode is set to the same potential as that of the output side electrode of the first bipotential lens so that the incident light is incident at the same speed and the intermediate electrode. A voltage having a polarity different from the polarity of the charged particle beam is applied to the output side electrode, and the output side electrode is grounded, and is decelerated by a potential difference between the acceleration voltage and the output side electrode that is grounded. A charged particle beam irradiation method characterized in that a charged particle beam is focused by an electric field formed by an emission side electrode and irradiated onto a grounded sample surface.