JP6207884B2 - Charged particle beam equipment - Google Patents

Description

  The present invention relates to a charged particle beam apparatus.

  The structure of the sample surface can be observed by focusing the electron beam through an electromagnetic lens, irradiating the sample while scanning the sample, and detecting secondary electron charged particles emitted from the sample. Such an apparatus is called a scanning electron microscope (hereinafter abbreviated as SEM).

  On the other hand, the structure of the sample surface can be observed by focusing the ion beam through an electromagnetic field lens, irradiating the sample while scanning it, and detecting secondary charged particles emitted from the sample. Such an apparatus is called a scanning ion microscope (hereinafter abbreviated as SIM).

  The ion species used for the surface observation is preferably a light mass such as hydrogen or helium. This is because the ion species having a light mass has a small effect of sputtering the sample surface and can minimize damage to the sample surface. Further, these ion beams have a feature that they are more sensitive to information on the surface of the sample than electron beams. This is because when hydrogen or helium ions enter the sample surface, the excitation region of the secondary charged particles is localized toward the sample surface as compared with the irradiation of the electron beam. In addition, since the electron beam property cannot be ignored in the electron beam, aberration occurs due to the diffraction effect. On the other hand, since the ion beam is heavier than electrons, the diffraction effect can be ignored.

  In addition, information reflecting the internal structure of the sample can be obtained by irradiating the sample with an ion beam and detecting ions transmitted through the sample. Such an apparatus is called a transmission ion microscope. In particular, if the sample is irradiated with a light ion species such as hydrogen or helium, the rate of transmission through the sample increases, which is suitable for observing the sample.

  On the other hand, if the sample is irradiated with a heavy ion species represented by oxygen, nitrogen, argon, krypton, xenon, gallium, indium, or the like, it is suitable for processing the sample by sputtering. In particular, a focused ion beam apparatus using a liquid metal ion source is known as an ion beam processing apparatus.

  A gas field ionization source (hereinafter abbreviated as GFIS) is suitable as an ion source used for the SIM. In GFIS, a high voltage is applied to a metal emitter tip having a tip radius of curvature of about 100 nm or less, and an electric field is concentrated on the tip. Then, a gas (ionized gas) is introduced in the vicinity of the tip, and the gas molecules are field-ionized and extracted as an ion beam. GFIS can generate an ion beam with a narrow energy width. In addition, since the ion generation source is small in size, a fine ion beam can be generated.

  In a SIM using GFIS (hereinafter abbreviated as GFIS-SIM), it is necessary to obtain an ion beam having a large current density on the sample in order to obtain a sample image with little noise. For this purpose, it is necessary to increase the ion emission angular current density of the field ion source. In order to increase the ion radiation angle current density, the density of the ionized gas in the vicinity of the emitter tip may be increased.

  Next, when the temperature of the emitter tip is cooled to a low temperature, the energy of the ionized gas molecules colliding with the emitter tip is reduced and aggregated, so that the density of the ionized gas molecules can be increased. As a means for cooling the emitter tip, a mechanical refrigerator is suitable. In order for the refrigerator to maintain its cooling performance, it is necessary to minimize heat inflow from the room temperature to the cold head of the refrigerator. For this reason, it is common to maintain a vacuum around the cold head, but unlike the vacuum around the tip, a high vacuum level (0.1 Pa or less) is sufficient to maintain the cooling performance. is there.

  It is also possible to increase the pressure of the ionized gas introduced around the emitter tip. However, when introduced at 1 Pa or more, there is a problem that the ion beam is neutralized by colliding with the ionized gas, and the ion beam current is reduced or glow discharge is performed. In order to solve such a problem, an ion emission angle is obtained by efficiently ionizing an ionized gas with limited supply by limiting a region where gas is ionized by forming a projection of several atoms at the tip of the emitter tip. It is known that the current density is improved.

  In addition, the ion beam emitted from the projection of the atom at the tip of the emitter tip has a very high directivity of several degrees, so when irradiating the sample through the electromagnetic lens, the position and angle of the emitter tip must be set. Need to adjust.

  As a conventional technique, for example, Patent Document 1 discloses that ion source characteristics are improved by forming a minute protrusion at the tip of an emitter tip. Patent Document 2 discloses a charged particle microscope that makes an ion irradiation system compact and shortens the ion optical length, thereby reducing the amplitude of relative vibration between the emitter tip and the sample and enabling high-resolution sample observation. It is disclosed. Patent Document 3 discloses an ion microscope provided with a refrigerant circulation circuit cooling mechanism that is installed independently of the SIM body from the refrigerator that cools the GFIS and circulates the refrigerant between the GFIS and the refrigerator. Yes.

JP 58-85242 A International Publication No. 2011/055521 JP 2011-14245 A

  There are the following problems in applying a GFIS in which a projection of several atoms is formed at the tip of an emitter tip to a charged particle microscope.

  In the gas field ion source, it is necessary to introduce an ionized gas in the vicinity of the emitter tip as described above. When impurity gas is mixed in this ionized gas, impurity gas molecules may be desorbed near the tip of the emitter tip. Or, when the degree of vacuum in the space where the tip is arranged is low, there is a possibility that the impurity gas originally present in the space is desorbed near the tip of the emitter tip. Due to the desorption of the molecules, the shape of the tip of the emitter tip changes, and the electric field near the tip changes. Due to this factor, the electric field fluctuates and the ion beam current fluctuates.

  In addition, there is an influence when impurities are desorbed at locations other than the tip of the emitter tip. Since the portion where the impurity gas is attached protrudes by the size of the impurity gas, the electric field is higher than other portions, and ion beam radiation may occur from that portion. If there is ion beam radiation from an impurity gas adsorption site, an amount of ionized gas corresponding to the ion beam radiation is consumed at that location. As a result, the supply amount of the ionized gas from the location of the atoms originally used as the ion source is reduced. Due to this factor, the ion beam current varies.

  An object of the present invention is to provide a charged particle beam apparatus capable of irradiating a stable ion beam by suppressing desorption of impurity gas at the tip of the emitter tip and its periphery.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-mentioned problems. For example, a charged particle beam apparatus including a charged particle irradiation column that makes a charged particle beam emitted from a charged particle source incident on a sample. A needle-shaped anode emitter tip, an extraction electrode disposed opposite to the emitter tip, a refrigerator having a cold head for cooling the emitter tip, and heat from the refrigerator to the emitter tip. A heat transfer section for transmitting, a drive mechanism for changing an angle of the emitter tip, a first space in which the drive mechanism and the cold head of the refrigerator are disposed, and a second space in which the emitter tip is disposed. A vacuum partition that separates the space, and the vacuum partition is connected to the emitter tip, and the vacuum partition is operated by the drive mechanism. A movable part which moves in response to, the charged particle beam device is provided.

ADVANTAGE OF THE INVENTION According to this invention, the charged particle beam apparatus which can irradiate the stable ion beam by suppressing desorption of impurity gas can be provided.
Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. Further, problems, configurations and effects other than those described above will be clarified by the description of the following examples.

It is a whole block diagram of a scanning ion microscope. It is an enlarged view of a gas field ionization ion source and a cooling mechanism in the scanning ion microscope of FIG. It is a figure which shows the structure which transfers heat from a mechanical refrigerator using the circulation of gas. It is a 2nd example of the vacuum partition in a scanning ion microscope. It is a 3rd example of the vacuum partition in a scanning ion microscope. It is a 4th example of the vacuum partition in a scanning ion microscope. It is an example of the refrigerator using a refrigerant | coolant.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The accompanying drawings show specific embodiments in accordance with the principle of the present invention, but these are for the understanding of the present invention, and are never used to interpret the present invention in a limited manner. is not.

  A charged particle beam apparatus is an apparatus that accelerates particles (charged particles) having a charge such as electrons and cations with an electric field and irradiates a sample. A charged particle beam apparatus performs observation, analysis, processing, and the like of a sample by utilizing an interaction between the sample and charged particles. The present invention can also be applied to a scanning electron microscope, a scanning transmission electron microscope, a transmission electron microscope, an ion microscope, a focused ion beam device, a composite device of these and a sample processing device, or an analysis / inspection device using these devices. . Further, the present invention exhibits a high effect in a field ion source, but other ion sources may be used unless otherwise mentioned.

  An example of a charged particle beam apparatus according to the present invention will be described with reference to FIGS. A first example of a scanning ion microscope will be described below as an ion beam apparatus. FIG. 1 shows an overall image of the scanning ion microscope apparatus 100, and FIG. 2 shows an enlarged view of the gas field ion source 1 and the cooling mechanism 4 in the scanning ion microscope apparatus 100.

  The scanning ion microscope apparatus 100 of this example includes a gas field ionization ion source 1, an ion beam irradiation system column 2, a sample chamber 3, a cooling mechanism 4, a vacuum exhaust mechanism 5, and a tip driving mechanism 6. Here, the gas field ion source 1, the ion beam irradiation system column 2, the sample chamber 3, and the cooling mechanism 4 are vacuum containers and are evacuated by the evacuation mechanism 5.

  The gas field ion source 1 includes a needle-like emitter tip (anode emitter tip) 11, an extraction electrode 13 disposed to face the emitter tip 11, a tip holder 16 that holds the emitter tip 11, and a gas introduction machine. 17 and a high-voltage power supply 18. The extraction electrode 13 has an opening 12 through which ions pass. The tip holder 16 is made of, for example, an insulator.

  Furthermore, the scanning ion microscope apparatus 100 of this example has a vacuum partition wall 7. The first space including the cooling mechanism 4 and the tip driving mechanism 6 and the second space including the emitter tip 11 of the gas field ion source 1, the ion beam irradiation system column 2, and the sample chamber 3 are vacuum partition walls. Two different vacuum vessels separated by 7. Here, the first space is referred to as a vacuum container 9, and the second space is referred to as a vacuum container 8.

  The gas introduction machine 17 includes a gas introduction pipe 171, a gas leak valve 172, a gas regulator valve 173, and a gas cylinder 174. The high voltage power supply 18 includes a power supply main body 181, a high voltage cable 182, and a high voltage terminal 183.

  An ionized gas such as helium, neon, argon, krypton, hydrogen, nitrogen, oxygen introduced from the gas introduction machine 17 is ionized at the tip of the emitter tip 11 maintained at a high voltage by the high voltage power source 18; Extracted as an ion beam 15.

  The ion beam irradiation system column 2 includes an electron optical system that causes an ion beam emitted from the gas field ion source 1 to enter the sample 31. The ion beam irradiation system column 2 includes a main body 20, a focusing lens 21 that focuses ions emitted from the gas field ion source 1, and a movable first aperture 22 that limits the ion beam 15 that has passed through the focusing lens 21. The first deflector 23 that scans or aligns the ion beam 15 that has passed through the first aperture 22, the second deflector 24 that deflects the ion beam 15 that has passed through the first aperture 22, and the first aperture 22. A second aperture 25 for limiting the ion beam 15, and an objective lens 26 for focusing the ion beam 15 that has passed through the first aperture 22 and the second aperture 25 on the sample 31.

  The sample chamber 3 includes a sample stage 32 on which the sample 31 is placed and a secondary particle detector 33. The sample chamber 3 is supported by a vibration isolation table 34. The vibration isolation table 34 prevents vibration from the floor from propagating to the emitter tip 11. The vibration isolation table 34 is connected to the floor via a damper 341. The damper 341 may be configured by an air spring or a rubber member. In addition, as the damper 341, an active damper may be used or used together as necessary.

  Note that the scanning ion microscope apparatus 100 may include other lenses, electrodes, detectors, and the like in addition to those described above, or some of them may be different from the above, and the configuration of the scanning ion microscope is not limited to this. .

  The ion beam 15 from the gas field ion source 1 is irradiated onto the sample 31 via the ion beam irradiation system column 2. Secondary particles from the sample 31 are detected by a secondary particle detector 33. Although not shown, an electron gun for neutralizing the charging of the sample 31 when the ion beam 15 is irradiated and a gas gun for supplying gas to the vicinity of the sample are provided. The gas gun supplies a deposition gas and a charge neutralizing gas.

  The cooling mechanism 4 is a mechanism for cooling the inside of the gas field ion source 1, that is, the emitter tip 11, the tip holder 16, and the like. The cooling mechanism 4 includes a refrigerator main body 41, a heat transfer rod 42, stranded wires 44 and 45, radiation shields 43 and 46, a rod support body 47, a vibration damper 48, and a refrigerator support body 49. .

  For example, when the Gifford McMahon type (GM type) refrigerator is used as the cooling mechanism 4, a compressor unit 411 (compressor) for circulating helium gas is installed, and a refrigerator is provided between the refrigerator main body 41 and the compressor 411. It is connected by a pipe 415 for use.

  The refrigerator main body 41 usually has a portion suitable for transmitting its cooling capacity. For example, FIG. 1 shows an example in which a GM type refrigerator is used. In this case, the portion suitable for cooling includes the first cold head 412 that has a higher refrigeration capacity than the second cold head 413 described later and can start cooling from a relatively high temperature. Or it is the 2nd cold head 413 which has the refrigerating capability lower in temperature reached than the 1st cold head 412, and can be made into a comparatively low temperature.

  The emitter tip 11 is connected to the second cold head 413 of the refrigerator main body 41 via the tip holder 16, the stranded wire 44, and the heat transfer rod 42, and is cooled. The radiation shield 46 is installed so as to surround the emitter tip 11, the tip holder 16, and the vacuum partition 7. The vacuum partition 7 is disposed inside the radiation shield 46 and is provided in the vicinity of the emitter tip 11. The radiation shield 46 is connected to the first cold head 412 via a radiation shield 43 and a stranded wire 45 installed so as to cover the heat transfer rod 42 and cooled.

  The heat transfer rod 42 may be supported by the rod support 47 within the radiation shield 43. At this time, in order to reduce heat from flowing from the radiation shield 43 to the heat transfer rod 42 having a temperature lower than that of the radiation shield 43 through the rod support 47, a member having a low thermal conductivity is used as the rod support 47. It is necessary to choose. Here, since the rod support 47 and the emitter tip 11 are located in different vacuum containers by the vacuum partition wall 7, the impurity gas emitted from the rod support 47 is prevented from adhering to the emitter tip 11. There is an effect. That is, regarding the member of the rod support 47, it is not necessary to be a member with a small amount of outgas corresponding to ultrahigh vacuum as in the prior art. Specifically, a member such as a fiber reinforced plastic may be used as the rod support 47.

  The vibration damper 48 is disposed between the main body 20 of the ion beam irradiation system column 2 and the refrigerator main body 41. Therefore, the vibration damper 48 reduces mechanical vibration generated in the refrigerator main body 41. For this reason, it is necessary to select a vibration damping material that hardly transmits vibration as the vibration damper 48. Here, since the vibration damper 48 and the emitter tip 11 are located in different vacuum containers by the vacuum partition wall 7, the impurity gas emitted from the inner wall of the vibration damper 48 is prevented from adhering to the emitter tip 11. There is an effect. In other words, the member of the vibration damper 48 does not have to be a member with a small amount of outgas corresponding to the ultrahigh vacuum as in the prior art. Specifically, a material such as rubber or gel may be used as the vibration damper 48.

  The vacuum exhaust mechanism 5 includes vacuum pumps 51 and 52, vacuum valves 53, 54, 55, 56 and 57, and pipes 58 and 59. The vacuum pump 51 evacuates the vacuum vessel 8 including the emitter tip 11 of the gas field ion source 1, the ion beam irradiation system column 2, and the sample chamber 3 via the pipe 59 and the vacuum valves 54, 55, 56, 57. Exhaust. The vacuum pump 51 may be a turbo molecular pump evacuated by an oil rotary pump or a dry pump.

  The vacuum pump 52 evacuates the vacuum container 9 including the refrigerator main body 41 and the tip drive mechanism 6 through the pipe 58 and the vacuum valve 53. The vacuum pump 52 may be an oil rotary pump or a dry pump. Alternatively, the vacuum pump 52 may be a turbo molecular pump that is evacuated by an oil rotary pump, a dry pump, or the like. Thus, the vacuum vessel 8 including the emitter tip 11 is evacuated by the vacuum pump 51, and the vacuum vessel 9 including the refrigerator main body 41 and the tip driving mechanism 6 is evacuated by the vacuum pump 52, and the two vacuum vessels 8 and 9 can be evacuated individually. Unlike the degree of vacuum around the tip, the vacuum vessel 9 is sufficient to maintain the cooling performance if it is about a high vacuum or higher (0.1 Pa or lower). In addition, since the two vacuum containers 8 and 9 are divided by the vacuum partition wall 7, the space around the emitter tip 11 becomes smaller than the conventional one. Therefore, the time required for evacuating from the periphery of the emitter tip 11 is reduced.

  Here, a configuration using two vacuum pumps 51 and 52 is given as an example, but in a state where the emitter tip 11 is sufficiently cooled, the vacuum valve 53 is closed and the operation of the vacuum pump 52 is stopped. Alternatively, the vacuum pump 52 can be removed. As a result, it is possible to prevent mechanical vibration that may occur due to the operation of the vacuum pump 52.

  Although not shown, in addition to the vacuum pump 52, an ion pump, a noble pump, a titanium sublimation pump, a non-evaporable getter pump, and the like are provided in the gas field ion source 1, the ion beam irradiation system column 2, and the sample chamber 3. It may be attached and evacuated.

  Furthermore, the gas field ionization ion source 1, the ion beam irradiation system column 2, and the sample chamber 3 may be configured such that differential evacuation is possible by limiting the conductance of evacuation. Although FIG. 1 illustrates a configuration in which conductance is limited at the focusing lens 21 and the objective lens 26, the conductance may be limited at other locations, for example, the opening 12 of the extraction electrode 13.

  When introducing the aforementioned ionized gas from the gas introduction machine 17, the vacuum valve 54 may be closed and the vacuum valves 55, 56, and 57 may be opened to evacuate. As a result, differential evacuation in which the pressure of the ionized gas around the emitter tip 11 is locally increased, and the sample 31 can be efficiently irradiated with the ion beam 15 without scattering the generated ions. Play.

  The tip drive mechanism 6 is for changing the angle of the emitter tip 11. The tip drive mechanism 6 includes a tip base mount 61 that supports the emitter tip 11 and the tip holder 16, a tip tilt mechanism 62, a movable metal bellows 63, and a fixed component 65. As shown in FIG. 2, the tip tilt mechanism 62 may be configured by a spherical seat 621, or may be configured by combining gears and shafts, although not illustrated.

  The tip drive mechanism 6 is used to accurately align the direction of the tip of the emitter tip 11 with the ion beam irradiation axis 64. By moving the tip base mount 61 along the spherical seat 621, the angle in the direction of the tip of the emitter tip 11 can be adjusted. This angle axis adjustment has the effect of reducing the distortion of the ion beam 15.

  The tip base mount 61 and the tip holder 16 are connected by a fixing component 65. Since the tip base mount 61 is usually at room temperature and the tip holder 16 is cooled to a low temperature when the apparatus is operated, the fixed component 65 that connects the tip base mount 61 and the tip holder 16 has low thermal conductivity. It is necessary to select parts. Here, since the fixed component 65 and the emitter tip 11 are located in different vacuum containers by the vacuum partition wall 7, there is an effect of preventing the impurity gas emitted from the fixed component 65 from adhering to the emitter tip 11. . That is, regarding the member of the fixed component 65, it is not necessary to be a member with a small amount of degas corresponding to ultra high vacuum as in the prior art. Specifically, a member such as a fiber reinforced plastic may be used as the fixed component 65.

  As shown in FIGS. 1 and 2, the vacuum partition 7 is a partition extending between the emitter tip 11 and the main body portion 20 of the ion beam irradiation system column 2. The vacuum partition 7 is in a state where there is no conductance between the vacuum vessel 8 including the emitter tip 11 of the gas field ionization ion source 1 and the vacuum vessel 9 including the refrigerator main body 41, that is, the vacuum vessel 8 and the vacuum vessel 9 This is a member that completely seals the gap and prevents gas or the like from moving.

  The vacuum partition 7 is connected to a vacuum seal portion 71 connected to the tip holder 16, a metal bellows (movable portion) 72 that moves according to the movement of the tip drive mechanism 6, and the main body portion 20 of the ion beam irradiation system column 2. The support part 73 is provided. By using the metal bellows 72, the vacuum vessel 8 including the gas field ion source 1 and the vacuum vessel 9 including the refrigerator main body 41 are isolated, and the orientation or position of the emitter tip 11 is changed by the tip drive mechanism 6. There is an effect that it is possible.

  In this example, an insulator is used as the tip holder 16, but when a metal, for example, copper, is used as a member of the tip holder 16, a high voltage applied to the emitter tip 11 is insulated by using an insulator as a member of the support portion 73. May be. In addition, the provision of the vacuum seal portion 71 provides an effect that the tip holder 16 can be removed upward when the emitter tip 11 is replaced.

  FIG. 3 shows an example in which gas circulation is used as means for transferring heat from the mechanical refrigerator to the emitter tip 11 in the scanning ion microscope apparatus 100 in particular. In this example, an example in which helium is used as a circulating gas will be described. By adopting this gas circulation unit 200, it is possible to reduce the propagation of the mechanical vibration generated by the operation of the mechanical refrigerator to the emitter tip 11. Description of the same parts as those described in FIGS. 1 and 2 is omitted.

  The gas circulation unit 200 includes a refrigerator main body 210, a helium circulation compressor unit 220 of the refrigerator, a heat exchanger A231, a heat exchanger B232, a heat exchanger C233, a heat exchanger D234, and a heat exchanger E235. A heat exchanger F236, a helium circulation compressor unit 240 for heat transfer, a transfer tube 250, and helium circulation pipes 251 and 252.

  As helium circulates in the helium circulation pipes 251 and 252, the cooling capacity generated in the refrigerator main body 210 is conducted to the emitter tip 11 and the radiation shield 46. The heat exchanger A231 performs heat exchange between normal temperature helium sent from the helium circulation compressor unit 240 and helium returned to the gas circulation unit 200 after cooling the radiation shield 46.

  The heat exchanger B232 performs heat exchange between the helium cooled through the heat exchanger A231 and the first cold head 211 of the refrigerator. The heat exchanger C233 performs heat exchange between helium returned to the gas circulation unit 200 after cooling the tip holder 16 and helium cooled through the heat exchanger B232.

  The heat exchanger D234 performs heat exchange between the helium cooled through the heat exchanger C233 and the second cold head 212 of the refrigerator. The heat exchanger E235 performs heat exchange between the helium sent from the helium circulation compressor unit 240 and the stranded wire 45 connected to the radiation shield 46. The heat exchanger F236 performs heat exchange with the stranded wire 44 connected to the tip holder 16.

  FIG. 4 is a second example of a vacuum partition wall in the scanning ion microscope of the present invention. In the example of FIG. 4, a part of the vacuum partition 7 (for example, the support portion 73) includes the folding mechanism 301. In the example of FIG. 4, the folding mechanism 301 includes two folding parts, but the invention is not limited to this, and it is sufficient that at least one folding part is provided.

  The folding mechanism 301 increases the distance from the apparatus main body room temperature section 302 to the tip holder 16 in the main body section 20 of the ion beam irradiation system column 2. For this reason, the heat inflow from the apparatus main body room temperature portion 302 to the emitter tip 11 is reduced, and as a result, the cooling temperature of the emitter tip 11 is lowered, and the current amount of the ion beam is increased. In addition, the amount of degassing is reduced due to a decrease in cooling temperature, and a stable ion beam can be irradiated.

  The folding mechanism 301 of the vacuum partition 7 is connected to the radiation shield 46. Since the radiation shield 46 serves as an escape path for heat inflow from the apparatus main body room temperature portion 302, the emitter tip 11 can be cooled more effectively.

  FIG. 5 is a third example of a vacuum partition wall in the scanning ion microscope of the present invention. In the example of FIG. 5, a part of the vacuum partition 7 (for example, the support portion 73) is connected to the extraction electrode 402 having the opening 403 through the insulator 401. According to this configuration, the emitter tip 11 is included in a part of the vacuum partition 7, the insulator 401, and the extraction electrode 402. In this example, the vacuum vessel 8 includes a first chamber containing the emitter tip 11 and a second chamber provided outside the first chamber.

  Here, a space enclosed by a part of the vacuum partition 7, the insulator 401, and the extraction electrode 402 is referred to as a first chamber 501. A space enclosed by the extraction electrode 402, a part of the vacuum partition 7 and the focusing lens 21 is defined as a second chamber 502. Furthermore, let the vacuum vessel 9 including the refrigerator main body 41 be the third chamber 503.

  The first chamber 501 may have a sealed structure except for the opening 403 of the extraction electrode 402. The first room 501 and the second room 502 are connected via an opening 403. A piping 59 for the vacuum pump 52 is connected to the second chamber 502. The second chamber 502 side is evacuated by the vacuum pump 52, and the first chamber 501 and the second chamber 502 are configured to be differentially evacuated through the opening 403.

  The first chamber 501 is provided with a mechanism for introducing ionized gas. Specifically, a gas introduction pipe 171 having a gas leak valve 172 is provided in the first chamber 501. The gas introduction pipe 171 is arranged so that ionized gas can be introduced in the vicinity of the emitter tip 11. With this configuration, the gas pressure is increased only in the space around the emitter tip 11. The introduced gas is evacuated through the opening 403 of the extraction electrode 402. By adopting such a differential exhaust structure, there is an effect of reducing scattering of ion beams by gas molecules.

  Moreover, since the insulator 401 and the extraction electrode 402 are connected to a part of the vacuum partition 7 (for example, the support portion 73) connected to the tip holder 16 cooled by the mechanical refrigerator, they are similarly cooled. . As a result, heat inflow due to radiation to the emitter tip 11 can be reduced. Therefore, the cooling temperature of the emitter tip 11 is lowered, and the amount of current of the ion beam emitted from the emitter tip 11 is increased.

  FIG. 6 is a fourth example of a vacuum partition wall in the scanning ion microscope of the present invention. In the example of FIG. 6, a mechanism for introducing gas is provided outside the first chamber 501, that is, in the second chamber 502. Specifically, the second chamber 502 is provided with a second gas inlet 404 having a variable leak valve 405. The second gas introduction port 404 is supplied with an etching gas having a function of shaping the emitter tip 11 from a gas cylinder (not shown) via the variable leak valve 405.

  As the etching gas, for example, a gas such as oxygen or nitrogen may be used. When the etching gas is introduced into the second chamber 502 in the structure as shown in this example, the portion where the gas having an etching action is cooled to the low temperature of the cooling mechanism 4 by the vacuum partition wall 7, for example, the second cold in FIG. It is not attracted to the head 413 or the stranded wire 44. Therefore, the area of the etching gas adsorption portion can be reduced, and the amount of etching gas adsorption can be reduced. As a result, the introduction of the etching gas is completed, the required time required for evacuating the periphery of the emitter tip 11 is reduced, and the degree of vacuum around the emitter tip 11 increases relatively quickly.

  FIG. 7 shows an example in which a refrigerant such as liquid nitrogen or liquid helium is used in place of the mechanical refrigerator as the cooling means for the emitter tip 11 in the present invention. The other parts are the same as in the above-described example, and thus the same reference numerals are given and description thereof is omitted.

  In the example of FIG. 7, a coolant such as liquid nitrogen or liquid helium is introduced into the coolant container 701 to cool the emitter tip 11. When cooling, the inside of the refrigerant container 701 may be evacuated by a vacuum pump or the like (not shown). By reducing the vapor pressure, the temperature of the refrigerant decreases, and the cooling temperature of the emitter tip 11 can be further lowered. Furthermore, if the refrigerant is solidified by this evacuation, vibration due to the boiling phenomenon of the refrigerant is reduced, and vibration transmitted to the emitter tip 11 can be reduced.

  From the above, according to the above-described embodiment, the scanning ion microscope apparatus 100 including the ion beam irradiation system column 2 that makes the ion beam emitted from the gas field ion source 1 incident on the sample 31 has the needle-like emitter tip. 11, an extraction electrode 13 disposed opposite to the emitter tip 11, a cooling mechanism 4 for cooling the emitter tip 11, a tip driving mechanism 6 for changing the angle of the emitter tip 11, a tip driving mechanism 6, and The vacuum partition 7 is provided to separate the first space in which the cooling mechanism 4 is disposed and the second space in which the emitter tip 11 is disposed. The vacuum partition 7 is connected to the emitter tip 11, and the vacuum partition 7 includes a metal bellows (movable part) 72 that moves according to the movement of the tip drive mechanism 6.

  According to this configuration, by using the vacuum bulkhead 7 that separates the emitter tip 11 side and the mechanical refrigerator side, most of the parts cooled to a low temperature other than the emitter tip 11 are located on the mechanical refrigerator side. The impurity gas adsorbed on the surface of the location is not desorbed and does not affect the emitter tip 11. Impurity desorption may occur by adjusting the temperature of the apparatus or by heat treatment during emitter tip molding. Desorption of impurity gas at and around the tip of the emitter tip can be suppressed, and a stable ion beam can be irradiated.

In addition, the emitter tip must be placed in a space (10 ⁻⁵ Pa or less) higher than the ultra-high vacuum as the degree of vacuum before introducing the ionized gas, and the purity of the ionized gas to be introduced must be kept better. Don't be. In order to obtain a high degree of vacuum, it is effective to use a means called baking that heats the container above room temperature in a state where the vacuum container is evacuated by a vacuum pump. However, the vacuum container and the vacuum sealing material need to be made of a metal that can withstand heating, a heat-resistant resin material, or the like, and there is a problem that costs increase. According to the above-described embodiment, the use of the vacuum partition wall 7 can minimize the number of expensive ultra-high vacuum compatible parts necessary for generating a stable ion beam, and a stable ion beam. It is possible to provide an inexpensive charged particle microscope that can be generated.

  For example, in a vacuum vessel that generates an ultra-high vacuum, a metal gasket is usually used for the vacuum seal portion, but by providing a vacuum partition wall 7, for example, in a region where no ultra-high vacuum is required on the mechanical refrigerator side, for example, made of rubber It becomes possible to use the sealing parts. This facilitates assembly of the device.

  Furthermore, in the area of the mechanical refrigerator side, not only the cost, but also members that are often degassed and heat-sensitive, which are not normally used in the ultra-high vacuum region, can be used. Increase. For example, for parts that support a low temperature cooling part and a room temperature member connected to each other, it is usual to use a member having a low thermal conductivity. In addition, a member with a small degassing amount in a vacuum must be selected. According to the above-described embodiment, since there is no such restriction on the mechanical refrigerator side, the apparatus can be reduced in size and weight.

  Furthermore, the angle of the emitter tip 11 can be adjusted by providing the vacuum partition 7 separating the emitter tip 11 side and the mechanical refrigerator side with mobility. Thereby, the axis of the ion beam 15 having very high directivity can be adjusted, and the sample 31 can be irradiated with the ion beam 15 having high brightness.

  Furthermore, the vibration generated by the operation of the mechanical refrigerator can be reduced at this connecting portion by using the movable vibration damper 48 for the connection between the mechanical refrigerator and the apparatus main body. In addition to the metal bellows, a member that is more effective in reducing vibrations, for example, a component made of a rubber member can be used for the connecting portion.

  In addition, this invention is not limited to the Example mentioned above, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. In addition, a part of the configuration of one embodiment may be replaced with the configuration of another embodiment, and the configuration of another embodiment may be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 100 ... Scanning ion microscope apparatus 1 ... Gas field ionization ion source 2 ... Ion beam irradiation system column 3 ... Sample chamber 4 ... Cooling mechanism 5 ... Vacuum exhaust mechanism 6 ... Tip drive mechanism 7 ... Vacuum partition 8, 9 ... Vacuum container 11 ... Emitter tip 12 ... opening 13 ... extraction electrode 15 ... ion beam 16 ... tip holder 17 ... gas introduction machine 171 ... gas introduction pipe 172 ... gas leak valve 173 ... gas regulator valve 174 ... gas cylinder 18 ... high voltage power supply 181 ... power supply body 182: High voltage cable 183: High voltage terminal 21 ... Focusing lens 22 ... First aperture 23 ... First deflector 24 ... Second deflector 25 ... Second aperture 26 ... Objective lens 31 ... Sample 32 ... Sample stage 33 ... Second Next particle detector 34 ... Vibration isolation table 341 ... Damper 41 ... Refrigerator body 42 ... Heat transfer 44, 45 ... Strands 43, 46 ... Radiation shield 47 ... Rod support 48 ... Vibration damper 49 ... Refrigerator support 411 ... Compressor 412 ... First cold head 413 ... Second cold head 415 ... Piping 51, 52 ... Vacuum pumps 53, 54, 55, 56, 57 ... Vacuum valves 58, 59 ... Piping 61 ... Tip base mount 62 ... Tip tilt mechanism 63 ... Metal bellows 65 ... Fixed parts 71 ... Vacuum seal part 72 ... Metal bellows 73 ... support part 200 ... gas circulation unit 210 ... refrigerator main body 220, 240 ... helium circulation compressor unit 231 ... heat exchanger A 232 ... heat exchanger B 233 ... heat exchanger C 234 ... heat exchanger D 235 ... heat exchanger E 236 ... heat exchanger F 250 ... transfer tube 251, 252 ... heliu Circulating piping 301 ... Folding mechanism 302 ... Apparatus body room temperature section 401 ... Insulator 402 ... Extraction electrode 403 ... Opening 404 ... Second gas inlet 405 ... Leak valve 501 ... First chamber 502 ... Second chamber 503 ... Third room 701 ... Refrigerant container

Claims (12)

A charged particle beam apparatus comprising a charged particle irradiation column that makes a charged particle beam emitted from a charged particle source incident on a sample,
A needle-shaped anode emitter tip;
An extraction electrode disposed opposite the emitter tip;
A cooling mechanism for cooling the emitter tip;
A drive mechanism for changing the angle of the emitter tip;
A first partition in which the drive mechanism and the cooling mechanism are disposed, and a vacuum partition that separates a second space in which the emitter tip is disposed;
The vacuum partition is connected to the emitter tip, and the vacuum partition includes a movable part that moves according to the movement of the drive mechanism ,
The second space includes a first room containing the emitter tip, and a second room provided outside the first room,
The charged particle beam apparatus according to claim 1, wherein a first gas introduction mechanism for introducing ionized gas is provided in the first chamber . The charged particle beam apparatus according to claim 1 ,
The charged particle beam apparatus according to claim 1, wherein the first chamber is formed by connecting a part of the vacuum partition wall to the extraction electrode through an insulator. The charged particle beam apparatus according to claim 1 ,
A vacuum evacuation mechanism connected to the second chamber;
The extraction electrode has an opening, and wherein said first chamber and said second chamber is configured to be a differential exhaust through the opening of the extraction electrode Charged particle beam device. The charged particle beam apparatus according to claim 1 ,
The charged particle beam apparatus according to claim 1, wherein a second gas introduction mechanism for introducing an etching gas is provided in the second chamber. The charged particle beam apparatus according to claim 1,
An emitter holder for holding the emitter tip;
The charged particle beam apparatus, wherein the vacuum partition includes a seal portion connected to the emitter holder, the movable portion, and a support portion connected to a main body portion of the charged particle irradiation column. The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus further comprising: a first evacuation mechanism connected to the first space; and a second evacuation mechanism connected to the second space. The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the cooling mechanism transfers heat to the emitter tip by gas circulation. The charged particle beam apparatus according to claim 1,
A charged particle beam apparatus, further comprising a vibration damper that connects the cooling mechanism and a main body of the charged particle irradiation column. The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the cooling mechanism includes a mechanical refrigerator. The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the cooling mechanism includes a refrigerant container containing a liquid refrigerant. A charged particle beam apparatus comprising a charged particle irradiation column that makes a charged particle beam emitted from a charged particle source incident on a sample,
A needle-shaped anode emitter tip;
An extraction electrode disposed opposite the emitter tip;
A cooling mechanism for cooling the emitter tip;
A drive mechanism for changing the angle of the emitter tip;
A first partition in which the drive mechanism and the cooling mechanism are disposed, and a vacuum partition that separates a second space in which the emitter tip is disposed;
The vacuum partition is connected to the emitter tip, and the vacuum partition includes a movable part that moves according to the movement of the drive mechanism,
The charged particle beam apparatus, wherein the vacuum partition includes a folding mechanism. The charged particle beam device according to claim 11,
A radiation shield connected to the cooling mechanism and surrounding the emitter tip;
The vacuum bulkhead is disposed inside the radiation shield;
The charged particle beam apparatus, wherein the folding mechanism is connected to the radiation shield.

Images