JP2018152365A - Ion beam apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion beam apparatus which can apply an ion beam with an ion energy changed in performing, by an ion beam, observation, processing or measurement, and which realizes ultra high-resolution observation, low-damage observation, high accuracy size measurement, or ultra fine high-speed processing according to setting conditions.SOLUTION: An ion beam apparatus comprises: a gas field ionization ion source which can ionize at least two kinds of gases; an electrostatic objective lens configured of four electrodes; and a controller which stores at least voltages applied to the respective electrodes of the electrostatic lens and a sample voltage to a first acceleration voltage when applying a first kind of gas ions, and voltages applied to the respective electrodes of the electrostatic lens and a sample voltage to a second acceleration voltage different from the first acceleration voltage when applying a second kind of gas ions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ion beam apparatus.

  By irradiating the sample while scanning electrons and detecting secondary charged particles emitted from the sample, the structure of the sample surface can be observed. This is called a scanning electron microscope (hereinafter abbreviated as SEM). On the other hand, the structure of the sample surface can also be observed by irradiating the sample while scanning with an ion beam and detecting secondary electrons, secondary ions, reflected ions, etc. emitted from the sample. This is called a scanning ion microscope (hereinafter abbreviated as SIM). In particular, if the sample is irradiated with a light ion species such as hydrogen or helium, the sputtering effect becomes relatively small, which is suitable for observing the sample. In addition, the element of the sample can be analyzed by examining the energy of the ions reflected by the sample and the angle at which the ions are emitted.

  Furthermore, the ion beam has a characteristic that it is more sensitive to information on the sample surface than the electron beam. This is because the excitation region of secondary electrons is localized on 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 the electron, the aberration due to the diffraction effect is extremely small compared to the electron. In particular, when a gas field ion source with high brightness is used, the ion beam can be focused extremely finely compared to the electron beam. That is, an ultra-high resolution of the sample surface is possible. In addition, the surface structure of the miniaturized semiconductor sample can be measured with high accuracy by performing line scanning or surface scanning on the sample using an extremely fine ion beam. If the sample is irradiated with a relatively heavy ion species, the sample can be processed by sputtering.

By the way, the gas field ion source supplies a gas such as hydrogen or helium to a metal emitter tip having a tip radius of curvature of about 100 nm, and applies a high voltage of several kV or more to the emitter tip to gas ionize the gas molecules. This is extracted as an ion beam. The feature of this ion source is that it is possible to generate an extremely fine ion beam because the energy width of ions is narrow and the size of the ion generation source is small. Further, in order to increase the ion radiation angle current density of the gas field ion source, the emitter tip is cooled to a very low temperature, and the pressure of the ionized gas around the emitter tip is set to about 10 ⁻² to several Pa, for example.

  In an ion beam device, the surface of the sample can be detected by irradiating the sample with a very fine ion beam and detecting secondary electrons (or ions), reflected electrons (or ions), transmitted electrons (or ions), etc. emitted from the sample. Observe the structure of the semiconductor with ultra-high resolution, measure the dimensions of the surface structure of a miniaturized semiconductor sample with high accuracy, or investigate the energy (electron) and emission angle caused by the sample. Analysis of sample elements is possible.

  When a sample is irradiated with an ion beam having energy, ions move sample atoms. A so-called cascade mixing phenomenon occurs. For example, the bond of the sample molecule is cut to change its property and density. In addition, a so-called sputtering phenomenon occurs in which part of the sample atoms jumps into the vacuum. If this is utilized, the sample can be finely processed. Further, when the sample is an insulator, a charging phenomenon of the sample occurs.

  In an ion beam apparatus equipped with a gas field ion source, when the gas type is changed, for example, in the case of hydrogen or helium having a small mass number, or in the case of argon or xenon having a relatively large mass number, first, The described cascade mixing phenomenon, sputtering phenomenon, charging phenomenon and the like are different. That is, when irradiated with hydrogen, helium, etc., the degree to which the sample structure is changed is relatively small, and the rate at which the sample is scraped by sputtering is also small. On the other hand, when argon or xenon is irradiated, the degree to which the sample structure is changed is relatively large, the ratio of scraping the sample by sputtering is large, and the speed is high when processing the sample.

  These phenomena also differ depending on the energy of the ion beam. In general, the greater the energy, the greater the degree to which the sample structure is changed. However, the sputtering rate when irradiating with hydrogen or helium is maximized from several keV to several tens keV. This also depends on the incident angle and material. On the other hand, increasing the energy of the ion beam is advantageous for reducing the ion beam diameter.

  In Patent Document 1, in a charged particle beam apparatus, the trajectory radius of a charged particle and the trajectory angle with respect to the central axis are controlled using four electrodes (V2 and V4, etc.) characterized by the tip shape. A technique for reducing chromatic aberration in the case of a constant condition of focusing electrons has been disclosed.

  Patent Document 2 discloses a technique for controlling the traveling speed of a charged particle beam and reducing chromatic aberration by providing acceleration electrodes 10 and 11 and a deceleration electrode 12 in five or more electrostatic lenses. Has been. The acceleration / deceleration electrode controls the traveling speed and does not change the convergence condition.

  Patent Document 3 discloses conditions for a gap between electrodes in an objective lens composed of four electrodes in a focused charged particle column. However, it is a disclosure of a conventional focused charged particle column, and the relationship between the electrode gap and the sample, the relationship between the electrode thickness and the electrode gap, etc. are not considered, and a gas field ion source is mounted. There is no description about operating the ion beam apparatus with high performance and multiple functions.

International Publication No. WO2009-119504 Japanese Patent Laid-Open No. 10-241616 JP2013-254722A

  In an ion beam apparatus equipped with a gas field ion source, an extremely fine ion beam can be formed, and ion species can be widely selected from different mass numbers. This ion beam device enables ultra-high resolution observation of the structure of the sample surface, high-precision measurement of the sample structure dimensions, sample element analysis, and ultra-fine processing, but the ion beam device equipped with a gas field ionization ion source However, there are problems as described below, which have not been realized with conventional ion beam apparatuses.

  First, the ion energy is reduced for the purpose of observing with a very high resolution without breaking the sample surface or measuring with a very high accuracy without changing the dimensions of the fine structure. For example, the ion acceleration voltage is set to a low acceleration of, for example, 5 kV or less. However, the decrease in the acceleration voltage increases the aberration of the electrostatic lens when the ion beam is focused. That is, the ion beam diameter increases and the observation resolution deteriorates. In order to overcome this problem, this problem can be overcome to some extent by making the ion beam apparatus a structure suitable for a low acceleration voltage. However, when the surface is hard to break, it has been found that, for example, observation and measurement with higher resolution becomes possible by increasing the ion energy by applying a high acceleration voltage of 40 kV or higher. In addition, unlike the conventional ion beam apparatus, the inventors have discovered that the characteristics of reduced sputtering efficiency at a high acceleration voltage are evident in a hydrogen beam or helium beam using a field ionization ion source. is there.

  That is, especially when measuring the dimensions of the sample surface structure, conventionally, only low-energy irradiation has been studied, but high-energy irradiation has not been studied. Depending on the structure and material of the sample, it has been found that high-precision dimensional measurement can be realized by selecting ion species and irradiating with high energy, and this has not been considered at all in the past. It is a characteristic.

  In particular, when measuring the dimensions of a fine device, it has been found that in order to reduce sample damage, it is necessary to optimize the ion irradiation energy according to the structure in the depth direction of the sample. That is, a function capable of irradiating with a plurality of ion energies is required, and further, it is necessary to refine the beam diameter with each ion energy. On the other hand, even when processing is intended, increasing the ion energy increases the processing speed, that is, the processing efficiency is improved.

  That is, in order to maximize the performance of an ion beam apparatus equipped with a gas field ion source, the problem of making the ion beam extremely fine with a plurality of ion species and a plurality of ion energies may become apparent. I understood. In a focused ion beam using a conventional Ga liquid metal ion source, the main purpose was high-speed and ultra-fine processing, so the problem of switching multiple irradiation conditions according to multiple objectives is not so obvious, It was not recognized as an issue.

  In order to solve the above problems, an ion beam apparatus according to the present invention includes a gas field ion source capable of ionizing at least two kinds of gas and an ion beam emitted from the gas field ion source by focusing with an electrostatic lens. An ion beam apparatus for irradiating a sample, the electrostatic lens closest to the sample facing the sample is composed of four electrodes, an acceleration power source capable of applying two different voltages, and the electrostatic lens A first power source capable of applying a different voltage to at least two of the four electrodes; and a second power source capable of applying a voltage to the sample or the sample stage. With respect to the first acceleration voltage when irradiating ions, the first applied voltage and the first sample voltage to each electrode of the electrostatic lens, and when irradiating the second kind of gas ions, Different from the one acceleration voltage Relative acceleration voltage, characterized in that it comprises a control unit for storing a second applied voltage and the second sample voltages to each electrode, the said electrostatic lens.

  In order to solve the above problems, an ion beam apparatus of the present invention includes an emitter tip, a gas field ion source that controls an ion beam emitted from the emitter tip, and a gas field ion source. A sample having an irradiation optical system for irradiating the sample with the ion beam, a charged particle detector for detecting charged particles resulting from irradiating the sample with the ion beam, and at least first to fourth electrodes In the ion beam apparatus having the electrostatic lens closest to the first electrode, the distance between the sample and the first electrode closest to the sample is the second electrode closest to the sample and the second electrode closest to the sample. The distance between the first electrode and the electrode and the thickness of the first electrode closest to the sample is less than or equal to the distance.

  In order to solve the above problems, an ion beam apparatus of the present invention includes an emitter tip, a gas field ion source that controls an ion beam emitted from the emitter tip, and a gas field ion source. A sample having an irradiation optical system for irradiating the sample with the ion beam, a charged particle detector for detecting charged particles caused by irradiating the sample with the ion beam, and first to fourth electrodes. An electrostatic lens, and the first to fourth electrodes have a first distance between a first electrode closest to the sample and a second electrode second closest to the sample, A second interval between the second electrode closest to the sample and a third electrode closest to the sample; and a fourth distance between the third electrode closest to the sample and the sample. Third distance to the nearest fourth electrode Any small to 1/10 or less as compared with, and the second distance is equal to or less than the third distance.

  According to the present invention, when observing, processing, and measuring with an ion beam, it is possible to irradiate the beam while changing the condition of ion energy, and it is possible to realize appropriate observation and processing under various conditions.

It is a schematic block diagram of an example of the ion beam apparatus by this invention. It is a schematic block diagram of an example of the control system of the ion beam apparatus by this invention. It is an example of the sample chamber internal structure of the ion beam apparatus by this invention. It is explanatory drawing of the electrostatic lens electrode space | interval of the ion beam apparatus by this invention. It is explanatory drawing of the electrostatic lens electrode space | interval of the ion beam apparatus by this invention. It is explanatory drawing of the electrostatic lens electrode space | interval of the ion beam apparatus by this invention. It is a schematic block diagram of an example of the ion beam apparatus by this invention. It is an example of the sample chamber internal structure of the ion beam apparatus by this invention. It is a schematic block diagram of an example of the ion beam apparatus by this invention. It is an example of the sample chamber internal structure of the ion beam apparatus by this invention.

  According to the present invention, when observing, processing, and measuring with an ion beam, it is possible to irradiate with changing ion energy. By using each configuration, ultra high resolution observation, low damage observation, high precision dimension measurement, Ultra fine high-speed processing can be realized.

  In addition, when the sample is an insulator, the charging phenomenon of the sample occurs, so the appearance of the sample surface is changed or the structural dimensions are changed. However, by using the present invention, appropriate conditions for observation etc. are set. can do. That is, it is possible to suitably obtain observation of an insulator and acquisition of sample element information.

  (1) According to the configuration of claim 1 at the time of filing, when observing, processing, and measuring with at least two kinds of gas ion beams emitted from the field ionization ion source, the ion energy condition is set. It is possible to change and irradiate. Then, when the ion beam is focused on the sample with respect to at least two different acceleration voltages, the focal length of the electrostatic lens composed of four electrodes is made different so that each acceleration voltage is different. Thus, the aberration of the electrostatic lens can be reduced.

  That is, the beam diameter on the sample can be reduced at each acceleration voltage. As a result, ultra high resolution observation can be realized by high acceleration voltage ion beam irradiation, while low damage observation can be realized by low acceleration voltage ion beam irradiation. Also, when measuring the sample structure dimensions by changing the acceleration voltage and irradiating the ion beam depending on the sample structure, highly accurate dimension measurement can be realized under each acceleration voltage condition.

  Further, even when fine processing is performed by irradiating an ion beam while changing the acceleration voltage depending on the sample material, ultra-fine high-speed processing can be realized under each acceleration voltage condition. In particular, by configuring the objective electrostatic lens with four electrodes, the optical axes of the electrodes can be made to coincide with each other with precision, and an extremely fine beam can be formed.

  In addition, when a positive voltage is applied to the sample by applying the first acceleration voltage to the emitter tip, the ion energy for irradiating the sample can be lowered, the sample is less damaged, and the structure of the sample surface is altered. Observation without making it possible to accurately measure the structural dimensions of the surface. Furthermore, compared to the case where no voltage is applied to the sample with the same ion energy, the ion energy passing through the ion lens is high, so the aberration of the ion lens is reduced, the ion beam diameter on the sample is reduced, and the resolution is high. Observation and dimension measurement are realized. Next, when the second acceleration voltage is applied, if a negative high voltage is applied to the sample, the ion energy for irradiating the sample can be increased, and the speed at which the sample is processed can be increased. That is, ultrafine high-speed processing can be realized.

(2) In addition, in the configuration of claim 2 at the time of filing, in addition to the effect of (1),
When a relatively low first acceleration voltage is applied to gas ions having a relatively small mass number, the damage to the sample is relatively small, and observation without altering the structure of the sample surface It becomes possible to accurately measure the structural dimensions of the surface. On the other hand, when a relatively high second acceleration voltage is applied to gas ions having a relatively large mass number, the sputtering efficiency of the sample can be relatively increased, and the processing speed of the sample can be increased. it can. That is, ultrafine high-speed processing can be realized.

  (3) If the configuration of claim 3 at the time of filing is used, in addition to the effect of (1), the collection efficiency of secondary electrons increases, so the signal / noise intensity ratio of the observation image is increased. Observation and dimension measurement are possible. This also makes it possible to shorten the observation time and improve the throughput.

  (4) In addition to the effect of (1), in addition to the effect of (1), depending on the sample structure and sample material, the sample damage is relatively small or the dimensional measurement accuracy is relative. The structural dimensions of the sample surface can be measured under extremely high conditions.

  (5) In addition to the effect of (5) at the time of filing, in addition to the effect of (1), the device manufacturing yield is improved, or a finer device can be manufactured.

(6) In addition, in the configuration of claim 6 at the time of filing, in addition to the effect of (1),
In addition to the above effect, secondary electrons emitted from the sample in a substantially vertical direction are accelerated in the direction of the ion lens, and this can be detected efficiently.

  (7) In addition to the effect of (1), in addition to the effect of (1), with an acceleration voltage of 0.5 kV to 2 kV, particularly low damage can be observed, and 40 kV to 100 kV. With acceleration voltage, particularly high acceleration processing is possible. Further, it should be noted that when hydrogen or helium is used, the sputtering rate is reduced, so that observation with particularly little structural change on the surface becomes possible.

  (8) According to the configuration of claim 8 at the time of filing, when the ion beam is focused on the sample with respect to at least two different acceleration voltages, the electrostatic lens comprising four electrodes By setting the distance between the electrodes as described above, the aberration of the electrostatic lens can be reduced with respect to each acceleration voltage.

  That is, the lens aberration can be reduced and the beam diameter can be reduced. Therefore, ultra high resolution observation can be realized by high acceleration voltage ion beam irradiation with hydrogen ions or helium ion species, while low damage observation can be realized by low acceleration voltage ion beam irradiation. Also, when measuring the sample structure dimensions by changing the acceleration voltage and irradiating the ion beam depending on the sample structure, highly accurate dimension measurement can be realized under each acceleration voltage condition.

  Further, even when fine processing is performed by irradiating an ion beam while changing the acceleration voltage depending on the sample material, ultra-fine high-speed processing can be realized under each acceleration voltage condition. For example, argon, krypton, and xenon ion species achieve particularly high acceleration processing. In addition, by configuring the objective electrostatic lens with four electrodes, the optical axes of the respective electrodes can be made to coincide with each other with high precision, and an extremely fine beam can be formed.

(9) In addition, in the configuration of claim 9 at the time of filing, in addition to the effect of (8),
Since the collection efficiency of secondary electrons is increased, observation and dimension measurement can be performed by increasing the signal / noise intensity ratio of the observation image. This also makes it possible to shorten the observation time and improve the throughput.

  (10) According to the configuration of claim 10 at the time of filing, in addition to the effect of (8), by providing a power source capable of applying three different voltages, at least two types of acceleration voltages can be provided. Thus, it is possible to achieve both stable application of high voltage and reduction of aberration. In addition, the cost of the apparatus is higher than when only two power sources are used, but the conditions for reducing the beam diameter can be optimized.

  (11) According to the configuration of claim 11 at the time of filing, in addition to the effect of (8), a first observation image obtained by detecting mainly secondary electrons emitted from the sample; Since it is possible to display two types of observation images, that is, a second observation image obtained by converting positive ions reflected by the sample into electrons and detecting this, it is related to the surface element information and state of the sample. It is suitable for obtaining information.

  (12) In addition to the effect of (8), the configuration of claim 12 at the time of filing is suitable for minimizing the ion beam diameter particularly when low-acceleration voltage ion beam irradiation is performed, and low damage. Observation can be realized. In addition, depending on the sample structure, high-precision dimension measurement can be realized even when the sample structure dimension is measured by ion beam irradiation at a low acceleration voltage.

  (13) In addition to the effect of (8), the configuration of claim 13 at the time of filing is suitable for minimizing the ion beam diameter particularly when high-acceleration voltage ion beam irradiation is performed. Resolution observation can be realized. In addition, depending on the sample structure, even when the sample structure dimension is measured by ion beam irradiation at a high acceleration voltage, highly accurate dimension measurement can be realized.

  (14) The configuration of claim 14 at the time of filing is suitable for minimizing the ion beam diameter particularly when the low acceleration voltage ion beam is irradiated, and low damage observation can be realized. In addition, depending on the sample structure, high-precision dimension measurement can be realized even when the sample structure dimension is measured by ion beam irradiation at a low acceleration voltage.

  (15) According to the configuration of claim 15 at the time of filing, in addition to the effect of (14), a first observation image obtained by detecting mainly secondary electrons emitted from the sample; Since it is possible to display two types of observation images, that is, a second observation image obtained by converting positive ions reflected by the sample into electrons and detecting this, it is related to the surface element information and state of the sample. Suitable for obtaining information

  An example of an ion beam apparatus according to the present invention will be described with reference to FIG. Below, the 1st example of a scanning ion microscope apparatus is demonstrated as an ion beam apparatus. The scanning ion microscope of this example includes a gas field ion source body 1, an ion beam irradiation system column 2, a sample chamber 3, and a cooling mechanism 4. Here, the gas field ion source 1, the ion beam irradiation system column 2, and the sample chamber 3 are in a vacuum vessel.

  The gas field ion source 1 is provided with a needle-like emitter tip 21, an extraction electrode 24 having an opening 27 through which ions pass, a fine filament 22, a cylindrical filament mount 23, And a cylindrical emitter base mount 64. Further, a gas supply pipe 25 at the tip of the gas supply mechanism 26 is connected to the vacuum container 15 to supply ionized gas around the emitter tip. In this embodiment, the gas to be ionized (ionized gas) is exemplified by helium.

  Further, an ion source evacuation pump 12 for evacuating the vacuum vessel 15 of the gas field ion source 1 is provided. Between the vacuum vessel 15 and the ion source evacuation pump 12, a valve 29 capable of shutting off the vacuum is disposed. Further, a vacuum pump 71 containing a non-evaporable getter material 70 is connected to the vacuum container 15 of the gas field ion source 1. The non-evaporable getter material is provided with a heating mechanism 72 in addition to the vacuum container. The heating mechanism is based on the principle of resistance heating, lamp heating, and the like.

  Further, a vacuum shut-off valve 74 is disposed between the ion source evacuation pump 12 and the vacuum vessel 15 and the vacuum pump 71 containing the non-evaporable getter material 70 and the vacuum vessel 15. Further, a vacuum pump 78 is connected to a vacuum pump containing the non-evaporable getter material via a valve 77 capable of blocking vacuum.

  Further, the gas field ion source 1 includes a tilt mechanism 61 that changes the tilt of the emitter tip 21, which is fixed to the emitter base mount 64. This is used to accurately align the direction of the tip of the emitter tip with the ion beam irradiation axis 62. This angle axis adjustment has the effect of reducing the distortion of the ion beam.

The ion beam irradiation system includes a focusing lens 5 that focuses ions emitted from the gas field ion source 1, a movable first aperture 6 that limits the ion beam 14 that has passed through the focusing lens, and the first aperture. A first deflector 35 that scans or aligns the ion beam that has passed through the first aperture, a second deflector 7 that deflects the ion beam that has passed through the first aperture, and a second aperture that restricts the ion beam 14 that has passed through the first aperture. 36. The objective lens 8 is an electrostatic ion lens that focuses the ion beam that has passed through the first aperture on the sample. The objective lens 8 is composed of four electrodes.
Although the interior of the sample chamber 3 will be described in detail later, a sample stage 10 on which the sample 9 is placed, a charged particle detector 11, and an electron gun for neutralizing the charge up of the sample when irradiated with an ion beam 16 is provided. The ion microscope of this example further includes a sample chamber evacuation pump 13 that evacuates the sample chamber 3. Although not shown, the sample chamber 3 is provided with a gas gun for supplying etching and deposition gas in the vicinity of the sample.

  In addition, a base plate 18 is disposed on the apparatus base 17 disposed on the floor 20 via a vibration isolation mechanism 19. The field ion source 1, the column 2, and the sample chamber 3 are supported by a base plate 18.

  The cooling mechanism 4 cools the emitter tip 21 inside the field ionization ion source 1. When the cooling mechanism 4 uses, for example, a Gifford-McMahon type (GM type) refrigerator or a pulse tube refrigerator, a compressor unit (not shown) using helium gas as a working gas (not shown) Compressor) is installed. The vibration of the compressor unit (compressor) is transmitted to the apparatus base 17 via the floor 20. A vibration isolation mechanism 19 is disposed between the apparatus base 17 and the base plate 18, and high-frequency vibrations of the floor are transmitted to the field ion source 1, the ion beam irradiation system column 2, the vacuum sample chamber 3, and the like. It has the feature of being difficult.

  Therefore, the vibration of the compressor unit (compressor) is not easily transmitted to the field ionization ion source 1, the ion beam irradiation system column 2, and the sample chamber 3 via the floor 20. Here, the refrigerator 40 and the compressor have been described as causes of the vibration of the floor 20. However, the cause of the vibration of the floor 20 is not limited to this.

  Further, the vibration isolation mechanism 19 may be configured by a vibration isolation rubber, a spring, a damper, or a combination thereof.

  Here, the structure and manufacturing method of the emitter tip 21 of the gas field ion source of the present embodiment will be described. First, a tungsten wire having a diameter of about 100 to 400 μm and an axial orientation of <111> is prepared, and its tip is sharply formed. Thereby, an emitter tip having a tip having a radius of curvature of several tens of nm is obtained. Iridium is vacuum deposited on the tip of this emitter tip in a separate vacuum vessel. Next, the filament is energized to heat the emitter tip at a high temperature, and iridium atoms are moved to the tip of the emitter tip. Thereby, a pyramid structure of nanometer order by iridium atoms is formed. Hereinafter, this is called a nano pyramid. Nanopyramids typically have a single atom at the tip, a layer of 3 or 6 atoms below it, and a layer of 10 or more atoms below it.

  In this example, a tungsten fine wire is used, but a molybdenum fine wire can also be used. In this example, an iridium coating is used, but a coating of platinum, rhenium, osmium, palladium, rhodium, or the like can also be used. However, the present application is not limited to the above example, and other manufacturing methods are possible.

  That is, as a method for forming the nanopyramid at the tip of the emitter tip, other methods such as field evaporation in vacuum, gas etching, ion beam irradiation, and remodeling may be used. By such a method, a nanopyramid of tungsten atoms or molybdenum atoms can be formed at the tips of tungsten wires or molybdenum wires. For example, when a <111> tungsten wire is used, the tip is composed of one or three tungsten atoms. Alternatively, a similar nanopyramid may be formed by etching in vacuum at the tip of a thin wire, such as platinum, iridium, rhenium, osmium, palladium, and rhodium. An emitter tip having a sharp tip structure of these atomic orders is called a nanotip.

  As described above, the emitter tip 21 of the gas field ion source according to the present embodiment is characterized by the nanopyramid. By adjusting the intensity of the electric field formed at the tip of the emitter tip 21, helium ions can be generated in the vicinity of one atom at the tip of the emitter tip. Accordingly, the region from which ions are emitted, that is, the ion light source is a very narrow region, which is below the nanometer. Thus, by generating ions from a very limited region, the beam diameter can be reduced to 1 nm or less. Therefore, the current value per unit area and unit solid angle of the ion source increases. This is an important characteristic for obtaining an ion beam with a fine diameter and a large current on a sample.

  When a nanopyramid with one tip atom is formed using platinum, rhenium, osmium, iridium, palladium, rhodium, etc., the current emitted from the unit area / unit solid angle, that is, the ion source is similarly applied. The luminance can be increased, which is suitable for reducing the beam diameter on the sample of the ion microscope or increasing the current. However, when the emitter tip is sufficiently cooled and the gas supply is sufficient, it is not always necessary to form a single tip, even if the number of atoms is 3, 6, 7, 10, etc. It can demonstrate sufficient performance. In particular, when the tip is composed of 4 or more and less than 10 atoms, the inventor of the present application has found that the ion source luminance can be increased and the tip atoms are less likely to evaporate and can be stably operated. .

  FIG. 2 shows an example of the control apparatus of the ion microscope according to the present invention shown in FIG. The control device of this example includes a field ionization ion source control device 91 that controls the gas field ion source 1, a refrigerator control device 92 that controls the refrigerator 4, a temperature control such as a heating mechanism and a cooling mechanism for the non-evaporable getter material. A device 191, a lens control device 93 for controlling the focusing lens 5 and the objective lens, a first aperture control device 94 for controlling the movable first aperture 6, a first deflector control device 195 for controlling the first deflector, a second A second deflector controller 95 that controls the deflector, a charged particle detector controller 96 that controls the charged particle detector 11, a sample stage controller 97 that controls the sample stage 10, and a pump 13 for evacuating the sample chamber are controlled. A plurality of power supplies 194 for applying a voltage to the vacuum pump control device 98, the electron gun control device 192, the sample stage 10, the electrodes of the charged particle detector 11 and the like. A control unit 193, and a main body control device 99 with the computing power. The main body control device 99 includes an arithmetic processing unit, a storage unit, an image display unit, and the like. The image display unit displays an image generated from the detection signal of the charged particle detector 11 and information input by the input unit.

  The sample stage 10 includes a mechanism that linearly moves the sample 9 in two orthogonal directions within the sample placement surface, a mechanism that linearly moves the sample 9 in a direction perpendicular to the sample placement surface, and the sample placement. It has a mechanism to rotate in the plane. The sample stage 10 further includes a tilt function that can vary the irradiation angle of the ion beam 14 to the sample 9 by rotating the sample 9 about the tilt axis. These controls are executed by the sample stage control device 97 in accordance with commands from the calculation processing device 99.

  FIG. 3 shows the inside of the sample chamber of the ion microscope according to the present invention shown in FIG. The objective lens 8 is composed of four electrodes 201, 202, 203, and 204. FIG. 4 schematically shows the interval between the electrostatic lens electrodes. The first interval s1 between the electrode 201 closest to the sample and the electrode 202 closest to the sample is the second interval s2 between the electrode 202 closest to the sample and the electrode 203 closest to the sample, And the third distance s3 between the third electrode 203 closest to the sample and the fourth electrode 204 closest to the sample is 1/10 or less, and the second distance s2 is smaller than the third distance s3. Are almost the same or smaller. Incidentally, “substantially the same” means a value close to or having the same value as a function and effect described later.

  When the distance between the electrode 201 closest to the sample and the sample is WD and the thickness of the electrode 201 is t1, the distance WD is substantially the same or smaller than the distance obtained by adding the first interval s1 and the thickness t1 of the electrode 201. It has become.

  Further, WD is substantially the same or smaller than the second interval s2. Furthermore, the first interval s1 is smaller than the thickness t1 of the electrode 201.

  Here, in FIG. 4A, each electrode shape is a flat donut disk with the same hole diameter, and the electrode interval is a disk distance parallel to the electrode distance. However, even if the lens electrode shape is not a donut disk having the same hole diameter, the hole diameter of each electrode may be different as shown in FIG. 4B, and the structure shown in the figure is formed on the side surface of the hole. May be.

  Further, a cup-shaped shape as shown in FIG. 4C may be used instead of a flat donut-shaped disk. In the electrode shape as shown in FIG. 4C, the electrode interval includes the closest distance s2a near the hole through which the ion beam passes and the interval s2b around the lens electrode. It was found that s2a should be substantially the same or smaller than s2b in order to reduce the aberration of the electrostatic lens and to achieve a stable structure that does not generate discharge when a high voltage is applied. For this reason, in the present invention, the distance between the electrodes is not the closest distance between the electrodes, but the closest distance near the hole through which the ion beam passes. Therefore, even if s2b is shorter than the s2a and s2b shown in the interval between the electrode 202 and the electrode 203 in FIG. 4C, the interval between the electrode 202 and the electrode 203 is s2a. However, although it is repeated, it is preferable that s2a is substantially the same or shorter than s2b. Similarly, the distance between the electrode 203 and the electrode 204 in FIG. 4C includes s3a and s3b, but the distance between the electrode 203 and the electrode 204 is s3a.

  In this embodiment, the first distance between the electrode 201 closest to the sample and the electrode 202 closest to the sample is 0.5 mm, the electrode 202 closest to the sample second, and the third closest to the sample. The second distance from the electrode 203 was 5 mm, and the third distance between the third electrode 203 closest to the sample and the fourth electrode 204 closest to the sample was 5 mm. However, the present invention is not limited to these values, and may be any value as long as the following effects can be obtained. As in the present embodiment, the first distance between the first electrode closest to the sample and the second electrode closest to the sample among the first to fourth electrodes of the electrostatic lens is the sample. A second interval between the second electrode closest to the second and a third electrode third closest to the sample, and a fourth distance closest to the third third electrode closest to the sample and a fourth electrode closest to the sample; When it is reduced to 1/10 or less compared to any of the third distances from the electrodes, it is suitable for minimizing the ion beam diameter particularly when low acceleration voltage ion beam irradiation is performed, and low damage observation can be realized. In addition, depending on the sample structure, high-precision dimension measurement can be realized even when the sample structure dimension is measured by ion beam irradiation at a low acceleration voltage.

  This is because when the gas field ion source is used under conditions not considered in the conventional charged particle beam column, since the ion source has high brightness and the energy width of the ions is small, the distance between the electrodes It was determined that a very small beam could be obtained if sufficient consideration was given.

  In this embodiment, the distance between the sample and the first electrode closest to the sample is a first interval between the first electrode closest to the sample and the second electrode closest to the sample; The distance is equal to or less than the distance including the thickness of the first electrode closest to the sample. In this way, in particular, ultra-high resolution observation can be realized by high acceleration voltage ion beam irradiation with hydrogen ions and helium ion species, while low damage observation can be realized by low acceleration voltage ion beam irradiation. Also, when measuring the sample structure dimensions by changing the acceleration voltage and irradiating the ion beam depending on the sample structure, highly accurate dimension measurement can be realized under each acceleration voltage condition.

  Further, even when fine processing is performed by irradiating an ion beam while changing the acceleration voltage depending on the sample material, ultra-fine high-speed processing can be realized under each acceleration voltage condition. For example, argon, krypton, and xenon ion species achieve particularly high acceleration processing. In addition, by configuring the objective electrostatic lens with four electrodes, the optical axes of the respective electrodes can be made to coincide with each other with high precision, and an extremely fine beam can be formed.

  In this embodiment, the distance between the sample and the first electrode closest to the sample is the second distance between the second electrode closest to the sample and the third electrode closest to the sample. It is smaller than that. In this way, even when a high acceleration voltage ion beam is irradiated, it is possible to ensure the voltage stability when the high voltage is applied after sufficiently shortening the focal length. That is, it is suitable for minimizing the ion beam diameter at a relatively high acceleration voltage, and ultrahigh resolution observation can be realized. In addition, depending on the sample structure, even when the sample structure dimension is measured by ion beam irradiation at a relatively high acceleration voltage, highly accurate dimension measurement can be realized.

  As described above, the relationship between the distance between the sample and the distance between the first electrode closest to the sample and the distance between the electrodes is not considered in the conventional charged particle beam column. In the case of using the present invention, the present inventor has obtained a simulation, a beam diameter, that the ion source has high brightness and the energy width of the ions is small, so that an extremely small beam can be obtained if the distance between the electrodes is sufficiently considered. It was ascertained by an experiment for evaluating the above and a dimension measurement experiment.

  In the present embodiment, the third distance between the third electrode closest to the sample and the fourth electrode closest to the sample is smaller than the thickness of the fourth electrode. This is suitable for minimizing the ion beam diameter particularly when low-acceleration voltage ion beam irradiation is performed, and low damage observation can be realized. In addition, depending on the sample structure, high-precision dimension measurement can be realized even when the sample structure dimension is measured by ion beam irradiation at a low acceleration voltage.

  In the conventional charged particle column and ion beam apparatus, the beam performance was not calculated considering the thickness of the electrode, but when considering the excellent performance of the gas field ion source, especially the thickness of the fourth electrode It was found that excellent performance can be obtained by characterizing up to.

  Further, as shown in FIG. 3, each electrode is electrically insulated, and a voltage can be applied from four high-voltage power supplies 301, 302, 303, and 304, respectively. However, the effects of the present invention can be obtained even when the high-voltage power supply 301 and the high-voltage power supply are not provided among the four high-voltage power supplies. In particular, in the case where the power source can be applied with different voltages to the two electrodes of the electrostatic lens or only two power sources are used, the device cost for the reduced power source can be reduced.

  The charged particle detector 11 includes an electrode 206 at the tip thereof, a phosphor 207, and a photomultiplier tube 208 on the atmosphere side. The electron gun 16 includes an electron emitter 209, an electron irradiation electrode 210, and the like. The electron emitter 209 and the electron irradiation electrode 210 are also electrically insulated, and a voltage can be applied from the two high-voltage power supplies 309 and 310. The sample stage 10 is also electrically insulated so that a voltage can be applied from the high voltage power source 305.

  Next, the operation of the gas field ion source of this example will be described with reference to FIG. Here, the ionized gas will be described as helium, for example. After sufficient time has elapsed after evacuation, the refrigerator 4 is operated. Thereby, the emitter tip 21 is cooled. First, a positive high voltage is applied as an ion acceleration voltage to the emitter tip. Next, a high voltage is applied to the extraction electrode 24 so as to have a negative potential with respect to the emitter tip. Then, a strong electric field is formed at the tip of the emitter tip. Helium supplied from the gas supply pipe 25 is pulled to the emitter tip surface by a strong electric field. Helium reaches the vicinity of the tip of the emitter tip 21 having the strongest electric field. Thus, helium is ionized and a helium ion beam is generated. The helium ion beam is guided to the ion beam irradiation system via the hole 27 of the extraction electrode 24.

  Next, the operation of the ion beam irradiation system will be described. The operation of the ion beam irradiation system is controlled by a command from the main body control device 99. The ion beam 14 generated by the gas field ion source 1 passes through the focusing lens 5, the beam limiting aperture 6, the objective lens 8, and the electrode 201 between the objective lens and the sample, and on the sample 9 on the sample stage 10. Is irradiated. First, the ion optical conditions were such that the magnification at which the ion light source was imaged on the sample was such that a large current was obtained (for example, 0.5 or more). The signal from the charged particle detector 11 is luminance-modulated and sent to the main body control device 99. The main body control device 99 generates a scanning ion microscope image and displays it on the image display unit. In this way, observation of the sample surface is realized.

  Here, in order to observe the sample while reducing damage to the sample, the ion acceleration voltage was set to 2 kV. The sample was set to ground potential. Of the four electrodes of the objective lens, 201, 203, and 204 were set to the ground potential, and a positive voltage was applied so that the ion beam was focused on the second closest electrode 202 from the sample. The voltage value of the electrode 202 is a positive high voltage (1 kV). At this time, the ion beam trajectory is formed by the electric field formed by the electrode 201 closest to the sample, the electrode 202 closest to the sample, and the electrode 203 closest to the sample among the four electrodes of the objective lens. Control to produce an effect of focusing on the sample. It should be noted that higher accuracy can be achieved by applying an auxiliary voltage to the electrode 203 closest to the sample to focus the ion beam on the sample. Here, in relation to the electrode 201 closest to the sample, the electrode 202 closest to the sample 202, and the electrode 203 closest to the sample 203, the electrode closest to the sample is the electrode 202 closest to the sample. 201 is arranged in an asymmetric position. Further, as the electrode shape, it is more preferable that the electrode 201 and the electrode 202 are substantially flat and suitable for the electrode 202 to be closer to the sample. At this time, even when the acceleration voltage is low accelerated (about 2 kV), the main surface of the objective lens can be formed near the electrode 202 that is second closest to the sample. In addition, since the voltage applied to the electrode 202 that is second closest to the sample is also low, sufficient reliability can be maintained even if the electrode 202 is brought close to the electrode 201. Furthermore, since the focal length of the objective lens can be shortened, the aberration of the lens can be reduced. That is, a sufficiently small beam diameter (about 1 nm) can be obtained even at the acceleration voltage of 2 kV. Therefore, observation with low damage can be realized by irradiation with a low acceleration voltage ion beam. In particular, a sufficiently small beam diameter (about 5 nm) can be obtained even at an acceleration voltage of 0.5 kV, but it has also been found that adjustment of the gas field ion source is difficult at a lower voltage.

  Next, in order to observe in more detail, an example of a high acceleration mode (ion acceleration voltage 50 kV) is shown. The sample was at ground potential. Of the four electrodes of the objective lens, the electrode 201, the electrode 202, and the electrode 204 were set to the ground potential, and a positive voltage was applied so that the ion beam was focused on the third closest electrode 203 from the sample. . The voltage value of the electrode 202 is a positive high voltage (40 kV) which is relatively higher than that in the low acceleration mode. At this time, of the four electrodes of the objective lens, an ion beam is generated by an electric field formed by the electrode 202 closest to the sample 202, the electrode 203 closest to the sample 203, and the electrode 204 closest to the sample. The trajectory is controlled and focused on the sample. At this time, the main surface of the objective lens is formed in the vicinity of the electrode 203 that is third closest to the sample. That is, it becomes longer than the focal length when the acceleration voltage is 2 kV. It should be noted that higher accuracy can be achieved by applying a voltage to the electrode 202 second closest to the sample to focus the ion beam on the sample. Although the focal length at this time slightly changes, the above-described effects can be achieved. Here, in relation to the electrode 202 closest to the sample, the electrode 203 closest to the sample 203, and the electrode 204 closest to the sample 204, the electrode 202 closest to the sample is the fourth closest to the sample. It is a feature that the electrode 204 close to is arranged in a symmetrical position. As for the electrode shape, the electrode 203 is thicker than the other electrodes and has an inclined structure toward the center. If a so-called Butler lens is used, the effect of reducing spherical aberration is further obtained. This configuration is particularly suitable for reducing lens aberration when the limit opening angle of the beam is increased to irradiate a large current ion beam. Further, as described above, if the electrode 201 and the electrode 202 have a flat structure and the electrode 203 and the electrode 204 have butler-type characteristics, it is very suitable for bringing about the effect of this embodiment.

  In particular, when the first acceleration voltage is 0.5 kV or more and 2 kV or less, and the second acceleration voltage is 40 kV or more and 100 kV or less, particularly low damage can be observed at an acceleration voltage of 0.5 kV to 2 kV. Thus, particularly high acceleration processing becomes possible at an acceleration voltage of 40 kV to 100 kV. It should be noted that, when hydrogen or helium is used, the sputtering rate is reduced, so that observation with particularly little surface structural change is possible.

  Further, the electrodes 202, 203, and 204 are sufficiently spaced so that they have sufficient reliability even when a high voltage of 40 kV is applied. Further, the electrode 203 that is the third closest to the sample is used as the sample. By sufficiently approaching the second closest electrode 202, the aberration of the lens can be reduced. That is, even in the high acceleration mode (acceleration voltage 100 kV), a minimum beam diameter of about 0.1 nm is obtained. Therefore, ultrahigh resolution observation can be realized by high acceleration voltage ion beam irradiation. However, it has also been found that when the voltage exceeds 100 kV, sufficient reliability cannot be obtained with an electrostatic lens having such a structure. Here, the super-high resolution when the ion acceleration voltage is 50 kV is emphasized. However, when hydrogen or helium is used as the ion species, the sputtering rate may decrease depending on the sample material. It was also found that the presence distribution of ions incident on the sample was wide and local damage was reduced. That is, it was found that when the acceleration voltage is set high, low damage observation or ultra high precision dimension measurement can be realized with low damage.

  Although helium gas is described in this embodiment, the present invention can be applied to other gases such as hydrogen, neon, argon, krypton, and xenon. Using relatively small mass numbers of hydrogen and helium is suitable for observing the surface of the sample electrode with an ion beam, and using relatively large mass numbers of neon, argon, krypton, and xenon, the sample is processed with an ion beam. Preferred.

  Here, especially when a relatively large mass number of neon, argon, krypton, or xenon is used, for example, when the sample is irradiated with a high acceleration voltage of 20 kV or more, the sputtering rate is improved. High-speed machining can be realized. Depending on the sample material, if an acceleration voltage of about 3 kV is applied to irradiate the sample, it can be processed with less damage.

  As described above, conditions such as the voltage applied to the objective lens when using a relatively high acceleration voltage (high acceleration mode), and application to the objective lens when using a relatively low acceleration voltage (low acceleration mode) Conditions such as the voltage to be stored are stored in the main body control device 99, and appropriate conditions are called in accordance with the purpose of ion beam irradiation and the structure and material of the sample to observe, process, and measure. In particular, if two or more different conditions are stored for a single wafer, the measurement can be switched with high accuracy in a short time, and the measurement throughput can be improved.

  In particular, in this embodiment, the objective electrostatic lens is configured by four electrodes, so that the optical axes of the electrodes can be made to coincide with each other with high accuracy. That is, aberrations can be reduced if the difference between the central axes of the electrodes is adjusted to be within 20 micrometers at most. This made it possible to form a very fine beam. However, even if the number of electrodes is four or more, if the electrode configuration is such that the effect of the present invention can be obtained, it is needless to say that even if the number of electrodes is supplementarily added, it is included in the scope of the idea of the present invention. Nor.

  In this embodiment, a positive high voltage is applied to the lens electrode, but a negative high voltage may be applied. At this time, although the absolute value of the applied voltage is increased, there is an effect that the aberration can be further reduced.

  As described above, in this embodiment, when observing, processing, and measuring with a gas ion beam, irradiation can be performed while changing ion energy. Then, when the ion beam is focused on the sample with respect to at least two different acceleration voltages, the focal length of the electrostatic lens composed of four electrodes is made different so that each acceleration voltage is different. Thus, the aberration of the electrostatic lens can be reduced. That is, the beam diameter on the sample can be reduced at each acceleration voltage.

  As a result, ultra high resolution observation can be realized by high acceleration voltage ion beam irradiation, while low damage observation can be realized by low acceleration voltage ion beam irradiation.

  Also, when measuring the sample structure dimensions by changing the acceleration voltage and irradiating the ion beam depending on the sample structure, highly accurate dimension measurement can be realized under each acceleration voltage condition. Further, even when fine processing is performed by irradiating an ion beam while changing the acceleration voltage depending on the sample material, ultra-fine high-speed processing can be realized under each acceleration voltage condition. According to the present invention, the above effects can be obtained.

  Further, in this embodiment, when the ion beam is focused on the sample with respect to at least two different acceleration voltages, when the relatively low first acceleration voltage is applied to the emitter tip, Among the four electrodes, when the voltage having the highest absolute value is applied to the electrode A that is relatively close to the sample and the second acceleration voltage that is relatively high is applied, 4 of the electrostatic lens. When a voltage having the highest absolute value is applied to the electrode B which is relatively far from the sample among the individual electrodes, the aberration of the electrostatic lens can be reduced with respect to each acceleration voltage. That is, the beam diameter on the sample can be reduced at each acceleration voltage.

  As described above, in this embodiment, there is an effect that high-resolution observation, low damage observation, high-accuracy dimension measurement, and ultrafine high-speed processing can be realized for each set condition.

  Next, an example of an ion beam apparatus according to the present invention will be described with reference to FIGS. 5, an example of the cooling mechanism 4 of the ion beam apparatus shown in FIG. 1 will be described in detail. The cooling mechanism 4 of this example employs a helium circulation system. FIG. 6 describes in detail an example of the objective lens and its surroundings in the sample chamber of the ion beam apparatus shown in FIG. In this example, the first electrode 211 is provided between the objective lens 8 which is an electrostatic lens closest to the sample and the sample so as to face the sample. Moreover, the gas supply means for supplying the gas can supply at least two kinds of gases, and can supply a gas having a relatively small mass number and a gas having a relatively large mass number.

  Next, an example of an ion beam apparatus according to the present invention will be described with reference to FIG. In this figure, an example of the cooling mechanism 4 of the ion beam apparatus shown in FIG. 1 will be described in detail. The cooling mechanism 4 of this example employs a helium circulation system.

  The cooling mechanism 4 of this example cools helium gas, which is a refrigerant, using the GM refrigerator 401 and the heat exchangers 402, 406, 407, and 408, and circulates this through the compressor unit 400. The helium gas pressurized at the compressor 403, for example, 0.9 MPa at a normal temperature of 300 K flows into the heat exchanger 402 through the pipe 409 and is cooled to a temperature of about 60 K through heat exchange with a return low-temperature helium gas described later. The The cooled helium gas is transported through a pipe 403 in the insulated transfer tube 404 and flows into a heat exchanger 405 disposed near the gas field ion source 1.

  Here, the heat conductor 406 thermally integrated with the heat exchanger 405 is cooled to a temperature of about 65K, and the above-described radiation shield and the like are cooled. The heated helium gas flows out of the heat exchanger 405 and flows into the heat exchanger 409 thermally integrated with the first cooling stage 408 of the GM refrigerator 401 through the pipe 407, and is cooled to a temperature of about 50K. And flows into the heat exchanger 410. It is cooled to a temperature of about 15 K by exchanging heat with a return low-temperature helium gas, which will be described later, and then flows into a heat exchanger 412 that is thermally integrated with the second cooling stage 411 of the GM refrigerator 401, Cooled to a temperature of about 9K, transported through a pipe 413 in the transfer tube 404, flowed into a heat exchanger 414 disposed near the gas field ion source 1, and good heat thermally connected by the heat exchanger 414 Cooling the conductive conductor 53 is cooled to a temperature of about 10K.

  The helium gas heated by the heat exchanger 414 sequentially flows into the heat exchangers 410 and 402 through the pipe 415 and exchanges heat with the above-described helium gas to reach a temperature of about 275 K at about room temperature. Collected in the unit 400. Note that the above-described bass portion is housed in the vacuum heat insulating container 416 and is connected to the transfer tube 404 in a heat insulating manner (not shown). In addition, in the vacuum heat insulating container 416, although not shown, the low temperature portion prevents heat from entering due to radiant heat from the room temperature portion by using a radiation shield plate, a laminated heat insulating material or the like.

  The transfer tube 404 is firmly fixed and supported on the floor 20 or a support body 417 installed on the floor 20. Here, although not shown, pipes 403, 407, 413, and 415, which are made of glass fiber plastic, which is a heat insulating material with low thermal conductivity, fixed and supported inside the transfer tube 404 by a heat insulator, are also fixed on the floor 20. It is supported. Further, near the gas field ion source 1, the transfer tube 404 is supported and fixed to the base plate 18. Similarly, here, although not shown, the transfer tube 404 is made of a glass fiber plastic that is a heat insulating material having a low thermal conductivity. Further, the pipes 403, 407, 413, and 415 fixed and supported inside the transfer tube 404 by a heat insulator are also fixed and supported by the base plate 18.

  That is, the present cooling mechanism expands the first high-pressure gas generated in the compressor unit 40 to generate cold, and cools it with the cold generated by the cold generating means and circulates in the compressor unit 400. It is a cooling mechanism that cools an object to be cooled with helium gas that is a second moving refrigerant.

  The cooling conduction rod 53 is connected to the emitter tip 21 through a deformable copper mesh wire 54 and a sapphire base. Thereby, cooling of the emitter tip 21 is realized. In this embodiment, the GM refrigerator causes the floor to vibrate, but the gas field ion source 1, ion beam irradiation system column 2, vacuum sample chamber 3, etc. are installed separately from the GM refrigerator. Furthermore, the pipes 403, 407, 413, and 415 connected to the heat exchangers 405 and 414 installed in the vicinity of the gas field ion source 1 are firmly fixed and supported on the floor 20 and the base 18 that hardly vibrate and do not vibrate. Furthermore, since it is vibration-insulated from the floor, it is characterized by a system with very little transmission of mechanical vibration.

  FIG. 6 shows the inside of the sample chamber of the ion microscope according to the present invention shown in FIG. The objective lens 8 is composed of four electrodes 201, 202, 203, and 204. Each electrode is electrically insulated, and a voltage can be applied from each of the four high-voltage power supplies 301, 302, 303, and 304. Moreover, the charged particle detector 11, the electron gun 16, etc. are provided. The electrode 211 arranged between the objective lens and the sample is shaped to wrap the lower part of the electrode 201 closest to the sample with the electrode of the objective lens, and this is also electrically insulated from other electrodes and the ground potential. Thus, a voltage can be applied from the high voltage power source 306.

  First, operations of the gas field ion source 1 and the ion beam irradiation system are the same as those of the ion beam apparatus described in the first embodiment. However, the gas supply means for supplying the gas can supply at least two kinds of gases, and can supply a gas having a relatively small mass number and a gas having a relatively large mass number. In addition, the gas field ionization ion source, the ion beam irradiation system, signal detection / image display emitted from the sample, and the like are also controlled by commands from the main body control device 99 as in the first embodiment. Next, operations of the objective lens, the electrode, the charged particle detector, etc. in the sample chamber will be described.

  First, the case where observation is performed with less damage to the sample will be described. As the gas, helium having a relatively small mass number was selected. In order to reduce the ion energy irradiated to the sample, the ion acceleration voltage is 8 kV, but a positive 4 kV is applied to the sample. Then, a positive 4 kV, which is the same voltage as the sample, is applied to the electrode 211 disposed between the objective lens and the sample. Further, a positive 4 kV, which is the same voltage as the sample, is applied to the lens electrode 201. Here, the electrode 211 and the lens electrode 201 function to substantially block the electric field from the ground potential of the vacuum chamber or the like in the space above the sample, and the potential of the electrode 211 arranged between the objective lens and the sample and the lens It is almost determined by the potential of the electrode 201. In this way, many of the secondary electrons emitted from the sample can be detected by the charged particle detector 11.

  Furthermore, in the present invention, a voltage smaller than the sample voltage is applied to the electrode 211 between the objective lens and the sample and the objective lens electrode 201 to repel secondary electrons that have jumped out in the opposite direction to the charged particle detector. Most of them can be detected with a charged particle detector. Then, we succeeded in obtaining a clear image with a higher signal / noise ratio. At this time, when the voltage higher than the positive voltage applied to the sample is applied to the electrode 206 at the tip of the charged particle detector to maximize the collection efficiency of secondary electrons, the signal / noise ratio However, a higher and clearer image could be obtained.

  That is, the secondary electrons emitted from the sample are accelerated in the direction of the charged particle detector by the electric field generated by the electrode 206 at the tip of the charged particle detector, so that the collection efficiency of the secondary electrons is particularly high. That is, there is an effect that the observation / dimension measurement can be performed by increasing the signal / noise intensity ratio of the observation image. At this time, if the voltages of the electrode 211 and the objective lens electrode 201 between the objective lens and the sample are adjusted again, the secondary electron collection efficiency may be increased.

  Of the four electrodes of the objective lens, 203 and 204 were set at ground potential, and a positive high voltage was applied so that the ion beam was focused on the 202 electrode closest to the sample on the sample. At this time, of the four electrodes of the objective lens, the electrode 201 closest to the sample, the electrode 202 second closest to the sample, the electrode 203 closest to the sample 203, the electrode 211, and the electric field formed by the sample To control the ion beam trajectory to focus on the sample. Note that the ion beam may be focused on the sample by supplementarily applying a voltage to the electrode 203 closest to the sample.

  Here, in relation to the electrode 201 closest to the sample, the electrode 202 closest to the sample 202, and the electrode 203 closest to the sample 203, the electrode closest to the sample is the electrode 202 closest to the sample. 201 is arranged in an asymmetric position. The acceleration voltage is as low as 8 kV, and the voltage applied to the electrode 202 closest to the sample is also low. Therefore, sufficient reliability can be maintained even when the electrode 202 is brought close to the electrode 201, and the focal length of the objective lens can be shortened, so that aberration of the lens can be reduced. That is, about 0.5 nm is obtained as a sufficiently small beam diameter even at the acceleration voltage of 8 kV and the ion energy of 4 kV. From this, low damage observation can be realized by irradiation with a low acceleration voltage ion beam.

  As described above, according to this example, by applying a positive voltage to the sample, ion energy for irradiating the sample can be lowered, the damage to the sample is reduced, and observation without changing the structure of the sample surface, It is possible to accurately measure the structural dimensions of the surface. Furthermore, since the energy of ions passing through the ion lens is high, the aberration of the ion lens is reduced, the ion beam diameter on the sample is reduced, and high-resolution observation and dimension measurement are realized. Furthermore, by providing an electrode 211 between the objective lens and the sample, and applying a voltage different from the positive voltage applied to the electrode 211 and the objective lens electrode 201 to the sample, the secondary electron trajectory is controlled. Since the collection efficiency of secondary electrons is increased, observation and dimension measurement can be performed by increasing the signal / noise intensity ratio of the observation image.

  This also makes it possible to shorten the observation time and improve the throughput. In particular, it has been found that even when the ion irradiation energy is 5 kV or less, the accuracy of dimension measurement can be 0.5 nm or less. Note that the same voltage is not necessarily applied to the electrode 211 and the objective lens electrode 201, and different voltages may be applied to maximize the collection efficiency of secondary electrons. Alternatively, the electrode 211 and the objective lens electrode 201 may be integrated. That is, a secondary electron collection efficiency may be maximized by applying a voltage smaller than the sample voltage to the integrated electrode.

  In addition, the shape of the electrode 211 between the objective lens and the sample is a shape that substantially surrounds the ion beam irradiation position of the sample as in this embodiment, rather than a flat plate shape. The inventor of the present application has found that the above can be improved. That is, observation and dimension measurement can be performed by increasing the signal / noise intensity ratio of the observation image. That is, even if a flat plate is simply placed between the objective lens and the sample and the same voltage as the sample is applied, the secondary electron collection efficiency decreases due to the influence of the ground potential entering from the side of the flat plate. .

  In addition, the shape of the electrode 211 between the objective lens and the sample and the shape of the objective lens electrode 201 is a shape that substantially surrounds the ion beam irradiation position of the sample, and at least one of the electrodes is made of a material having at least a permeability of 100 or more. Thus, it was found that the ion beam can be miniaturized by reducing magnetic field AC noise near the sample.

  Further, if a coil or magnet that generates a magnetic field is arranged near the sample stage 10 to accelerate the secondary electrons emitted from the sample in the direction of the charged particle detector, the secondary electron collection efficiency can be further increased. I found that it could be increased. That is, there is an effect that the observation / dimension measurement can be performed by increasing the signal / noise intensity ratio of the observation image.

  Further, the voltage applied to the phosphor 207 of the charged particle detector 11, the voltage applied to the objective lens electrode 201, the electrode 211 between the objective lens and the sample, and the electrode 206 arranged in the previous stage of the charged particle detector are applied. It has been found that if any one of the voltages can be controlled in conjunction with the voltage applied to the sample 9, the optimum secondary electron collection condition can be easily reproduced even if the sample voltage is changed. In particular, even when the ion energy is changed by changing the voltage applied to the sample, there is an effect that the collection efficiency of secondary electrons can be kept optimal, or the detection sensitivity of secondary electrons can be made constant. .

  Further, a positive voltage that is smaller than the voltage applied to the sample 9 is applied to the electron emitter 209 of the electron gun 16, and the voltage applied to the electron irradiation electrode 210 is larger than the voltage applied to the electron emitter 209. Thus, it was found that the sample can be irradiated with an electron beam, and when the sample is charged with an insulator, the sample can be favorably observed by neutralizing the sample. Furthermore, by applying a positive voltage that is approximately the same as or smaller than the voltage applied to the electrode 211 between the objective lens and the sample, the collection efficiency of secondary electrons can be increased. all right. That is, particularly when the sample is an insulator, since the charged state of the sample can be controlled by electron beam irradiation, there is an effect that the insulator can be observed and dimensions can be measured.

  Further, if the vacuum chamber material such as the gas field ion source, ion beam irradiation system and sample chamber is made of a magnetic material and shields the external magnetism, the diameter of the ion beam is reduced, and an effect of realizing higher resolution observation is achieved. .

  In addition, as shown in the present embodiment, when the emitter tip of the gas field ion source is configured with a nanopyramid, an ion beam with a very small beam diameter and a large current can be obtained, so a high signal / noise ratio can be obtained. There is an effect that an ultra-high resolution sample observation image can be obtained, and that the sample observation image can be prevented from shaking.

  Further, in the ion beam apparatus equipped with the gas field ion source, if the charged particle beam apparatus is characterized in that the magnification for projecting the ion light source onto the sample is at least 0.5 or more, in particular, the ion beam current is When the ion beam apparatus becomes larger and scans the ion beam emitted from the gas field ion source and irradiates the sample to detect the secondary particles emitted from the sample to obtain a sample observation image, a high signal is obtained. The sample observation image with ultra-high resolution can be obtained with the / noise ratio, and the sample observation image can be prevented from being shaken.

  Furthermore, by observing the ion emission pattern from the emitter tip with another vacuum device, adjusting the tilt direction of the emitter tip precisely, and then introducing it into the device of this embodiment, the tilt changing the tilt of the emitter tip. The mechanism can be omitted or the tilt range can be reduced. As a result, the ion source structure can be simplified, and thus a low-cost apparatus can be realized.

  Furthermore, according to the above embodiment, in the above gas field ion source, the ionization region is limited by making the tip of the emitter tip a nanopyramid composed of atoms. As a result, the sample can be observed with higher resolution. In addition, since the total ion current is smaller at this time, there is an effect that a gas field ion source having a higher utilization efficiency of the ionized gas can be provided by circulating the ionized gas.

  Furthermore, according to the gas field ion source and the ion beam apparatus of the present invention, vibration from the cooling mechanism is not easily transmitted to the emitter tip, and the emitter base mount fixing mechanism is provided to prevent the emitter tip from vibrating. High resolution observation is possible.

  Furthermore, the inventor of the present application has found that the sound of the compressor unit 40 or the compressor unit 400 causes the field ionization ion source 1 to vibrate and degrades its resolution. Therefore, in this example, a cover 417 for spatially separating the compressor and the field ion source is provided. Thereby, the influence of the vibration resulting from the sound of a compressor can be reduced. Thereby, high-resolution observation becomes possible.

  In the present embodiment, the second helium gas is circulated using the compressor unit 400. Although not shown, the flow rates of the pipes 111 and 112 of the compressor unit 40 are adjusted via the flow rate adjusting valve. The pipes 409 and 416 are communicated with each other through the valve, and a circulating helium gas is supplied into the pipe 409 using a part of the helium gas of the compressor unit 40 as the second helium gas. Even if recovered, the same effect is produced.

  Moreover, in this example, although the GM type refrigerator was used as the compressor unit 40 and the compressor unit 400, you may use a pulse tube refrigerator or a Stirling type refrigerator instead. In this example, the refrigerator has two cooling stages, but may have a single cooling stage, and the number of cooling stages is not particularly limited. For example, a compact and low-cost ion beam apparatus can be realized by using a small Stirling refrigeration having a single cooling stage and a helium circulation refrigerator having a minimum cooling temperature of 50K. In this case, neon gas or hydrogen gas may be used instead of helium gas.

  Further, in the case of this example, it was found that when the helium compressor 400 is stopped at the time of scanning ion image acquisition, the vibration noise of the scanning ion image is reduced, and a clear and high resolution image can be obtained. In this case, while the temperature of the ion emitter does not cause a large current change, the helium compressor 400 is driven to circulate helium, thereby reducing the temperature. According to this method, it has been found that a noise reduction effect is more easily produced than when the operation of the refrigerator is stopped during scanning ion image acquisition. Furthermore, the present inventors have found that both the operation of the helium compressor and the refrigerator are stopped, noise is further reduced, and a clear and high-resolution image can be obtained.

  Next, a case where fine processing is performed in the present embodiment will be described. As the gas, xenon having a relatively large mass number was selected as an example. First, the ion acceleration voltage was set to a relatively high acceleration (20 kV). Further, a negative high voltage of 5 kV was applied to the sample. That is, the ion energy is 25 kV. Of the four electrodes of the objective lens, 202 and 204 were set to the ground potential, and a positive high voltage of 15 kV was applied so as to focus the ion beam on the third closest 203 electrode from the sample. At this time, of the four electrodes of the objective lens, the electrode 202 is the second closest to the sample 202, the electrode 203 is the third closest to the sample, the electrode 204 is the fourth closest to the sample, the electrode 211, and the sample. The ion beam trajectory is controlled by an electric field to focus on the sample. At this time, the main surface of the objective lens is formed in the vicinity of the electrode 203 that is third closest to the sample. That is, the acceleration voltage is longer than the focal length when the acceleration voltage is relatively low (8 kV). It should be noted that higher accuracy can be achieved by applying a voltage to the electrode 202 second closest to the sample to focus the ion beam on the sample. Although the focal length at this time slightly changes, the above-described effects can be achieved. By doing so, it is possible to achieve both stable application of high voltage and reduction of aberrations.

  Here, in relation to the electrode 202 closest to the sample, the electrode 203 closest to the sample 203, and the electrode 204 closest to the sample 204, the electrode 202 closest to the sample is the fourth closest to the sample. It is a feature that the electrode 204 close to is arranged in a symmetrical position. These electrodes are sufficiently spaced so that they have sufficient reliability even when a high voltage of 15 kV is applied. Furthermore, the electrode 203 closest to the sample is sufficient for the electrode 202 second closest to the sample. By bringing them closer, the aberration of the lens can be reduced. That is, a minimum beam diameter (about 0.4 nm) can be obtained even at the acceleration voltage of 20 kV. From this, high-speed fine processing can be realized by irradiation with a high acceleration voltage ion beam.

  Then, a negative high voltage 5 kV that is the same voltage as the sample is applied to the electrode 211 disposed between the objective lens and the sample. Further, a negative high voltage 5 kV, which is the same voltage as the sample, is applied to the lens electrode 201. Here, the electrode 211 and the lens electrode 201 function to substantially block the electric field from the ground potential of the vacuum chamber or the like in the space above the sample, and the potential of the electrode 211 arranged between the objective lens and the sample and the lens It is almost determined by the potential of the electrode 201. In this way, many of the secondary electrons emitted from the sample can be detected by the charged particle detector 11.

  Furthermore, in the present invention, a voltage lower than the sample voltage is applied to the electrode 211 between the objective lens and the sample and the objective lens electrode 201 to repel secondary electrons that have jumped out in the opposite direction to the charged particle detector. It was made possible to detect with a charged particle detector. As a result, we succeeded in obtaining clear images with a higher signal / noise ratio. At this time, if a positive voltage is applied to the electrode 206 at the tip of the charged particle detector to maximize the collection efficiency of secondary electrons, a clear image with a higher signal / noise ratio can be obtained. I was able to. That is, the secondary electrons emitted from the sample are accelerated in the direction of the charged particle detector by the electric field generated by the electrode 206 at the tip of the charged particle detector, so that the collection efficiency of the secondary electrons is particularly high. In other words, the signal / noise intensity ratio of the observation image can be further increased to enable observation and dimension measurement.

  In addition, as described above, when applying a relatively low acceleration voltage to gas ions having a relatively small mass number (low acceleration mode), conditions such as voltage applied to the objective lens and sample voltage, and relative Conditions such as the voltage applied to the objective lens and the sample voltage when a relatively high acceleration voltage (high acceleration mode) is applied to gas ions having a large mass number are stored in the main body control device 99. Depending on the purpose of ion beam irradiation and the structure and material of the sample, the appropriate conditions are called for observation, processing, and measurement.

  In this way, when observing / processing / measuring with a gas ion beam, it becomes possible to irradiate with changing ion energy, and in the same way as the effect described in the first embodiment, in accordance with setting conditions, High-resolution observation, low damage observation, high-accuracy dimension measurement, and ultra-fine high-speed machining can be realized. Furthermore, when a relatively low first acceleration voltage is applied to gas ions having a relatively small mass number, the sample is relatively less damaged, and observation is performed without altering the structure of the sample surface. In addition, it is possible to accurately measure the structural dimensions of the surface. On the other hand, when a relatively high second acceleration voltage is applied to gas ions having a relatively large mass number, the sputtering efficiency of the sample can be relatively increased, and the processing speed of the sample can be increased. it can. That is, there is an effect that ultra-fine high-speed machining can be realized.

  Gases having a relatively small mass number include hydrogen and helium, and gases having a relatively large mass number include neon, argon, oxygen, nitrogen, krypton, and xenon, but are not limited to these elements. It is not something.

  In particular, in this embodiment, the objective lens is configured by four electrodes, so that the optical axes of the respective electrodes can be made to coincide with each other with high accuracy. That is, the difference in the central axis of each electrode can be adjusted within 10 micrometers to reduce aberrations. This made it possible to form a very fine beam. However, even if the number of electrodes is four or more, the effect of the present invention can be obtained if the same electrode configuration is used. Even if the number of electrodes is supplementarily added, the scope of the present invention is not escaped.

  In addition, as described above, by providing a power source capable of applying three different voltages to at least three of the four electrodes of the objective lens, it is stable against at least two types of acceleration voltages. It is possible to achieve both high voltage application and reduction of aberration. In addition, the cost of the apparatus is higher than when only two power sources are configured, but the effect of optimizing the conditions for reducing the beam diameter is achieved.

  Furthermore, if a power supply capable of applying four different voltages is provided on all four electrodes of the four electrodes of the electrostatic lens, stable high voltage application can be applied to at least two types of acceleration voltages. And reducing aberrations. In addition, the cost of the apparatus is higher than when only two power sources are configured, but the effect of optimizing the conditions for reducing the beam diameter is achieved.

  In this embodiment, a positive high voltage is applied to the lens electrode, but a negative high voltage may be applied. At this time, although the absolute value of the applied voltage is increased, there is an effect that the aberration can be further reduced.

  As described above, in this embodiment, when observing, processing, and measuring with a gas ion beam, irradiation can be performed while changing ion energy. Then, when the ion beam is focused on the sample with respect to at least two different acceleration voltages, the focal length of the electrostatic lens composed of four electrodes is made different so that each acceleration voltage is different. Thus, the aberration of the electrostatic lens can be reduced. That is, the beam diameter on the sample can be reduced at each acceleration voltage. As a result, ultra high resolution observation can be realized by high acceleration voltage ion beam irradiation, while low damage observation can be realized by low acceleration voltage ion beam irradiation. Also, when measuring the sample structure dimensions by changing the acceleration voltage and irradiating the ion beam depending on the sample structure, highly accurate dimension measurement can be realized under each acceleration voltage condition. Further, even when fine processing is performed by irradiating an ion beam while changing the acceleration voltage depending on the sample material, ultra-fine high-speed processing can be realized under each acceleration voltage condition. According to the present invention, the above effects can be obtained.

  Further, in this embodiment, when the ion beam is focused on the sample with respect to at least two different acceleration voltages, when the relatively low first acceleration voltage is applied to the emitter tip, Among the four electrodes, when the voltage having the highest absolute value is applied to the electrode A that is relatively close to the sample and the second acceleration voltage that is relatively high is applied, 4 of the electrostatic lens. When a voltage having the highest absolute value is applied to the electrode B which is relatively far from the sample among the individual electrodes, the aberration of the electrostatic lens can be reduced with respect to each acceleration voltage. That is, the beam diameter on the sample can be reduced at each acceleration voltage.

  In this way, when observing / processing / measuring with a gas ion beam, it becomes possible to irradiate with changing ion energy, and in the same way as the effect described in the first embodiment, in accordance with setting conditions, High-resolution observation, low damage observation, high-accuracy dimension measurement, and ultra-fine high-speed machining can be realized. Furthermore, a first electrode is provided between the electrostatic lens closest to the sample and the sample so as to face the sample, and a voltage different from the positive voltage applied to the sample is applied to control the trajectory of the secondary electrons. As a result, the collection efficiency of the secondary electrons is increased, so that the observation / dimension measurement can be performed by increasing the signal / noise intensity ratio of the observation image. This also makes it possible to shorten the observation time and improve the throughput. According to the present invention, the above effects can be obtained.

  Further, as shown in the present embodiment, an acceleration power source that can apply at least two different voltages to the emitter tip, a power source that applies a voltage to the extraction electrode, a power source that applies a voltage to the electrostatic lens, and a voltage to the sample And a control device that stores at least two types of values of the extraction electrode voltage, the electrostatic lens electrode voltage, and the sample voltage for different acceleration voltages, and is controlled according to the sample. If an ion beam apparatus that calls the conditions stored in the apparatus and measures the structural dimensions of the sample surface is used, two or more types including either hydrogen or helium are used to measure the structural dimensions of the sample surface with a gas ion beam. A gas suitable for measurement can be selected from these gases, and irradiation can be performed while changing the acceleration voltage. Depending on the sample structure and the sample material, it is possible to measure the structural dimension of the sample surface under the condition that the sample damage is relatively small or the dimension measurement accuracy is relatively high.

  In addition, if a system for managing the device manufacturing process is constructed using the result of measuring the structural dimensions of the sample surface with the ion beam apparatus of this embodiment, the device manufacturing yield can be improved, or a finer device can be manufactured. There is an effect that it can be manufactured.

  Next, the tip of the emitter tip is a nanopyramid composed of atoms, and using a hybrid particle source that extracts an ion beam or electrons from the needle-like emitter tip, the sample surface, sample processing, and observation inside the sample are performed. An ion beam apparatus that can make full use of complex sample analysis will be described with reference to FIG. In addition, the description about the content which overlaps with Examples 1 and 2 is omitted.

  The ion beam apparatus of the present embodiment is a nanopyramid in which the tip of the emitter tip 21 is composed of atoms, a hybrid particle source 501 that extracts an ion beam or electrons from the needle-like emitter tip, and a cooling mechanism 4 for the hybrid particle source. , Vacuum pump 12, hybrid irradiation system 502 for irradiating the sample with an electron beam and an ion beam, sample stage 503, secondary electron detector 304 for detecting secondary electrons emitted from sample 9, and charged particles transmitted through the sample An optical system 505 for image formation, a detector 506, a vacuum pump 13, and the like. In this apparatus, the cooling mechanism 4 is a cooling mechanism using liquid nitrogen and solid nitrogen as refrigerants.

  Here, it is possible to select and connect either a positive high voltage or a negative high voltage power source to the emitter tip. That is, a positive ion beam can be extracted from the emitter tip when a positive high voltage is applied, and an electron beam can be extracted from the emitter tip when a negative high voltage is applied. In addition, at least two kinds of gases can be introduced into the hybrid particle source. That is, it is possible to introduce at least two kinds of gases including any one of hydrogen and helium and any one of neon, argon, krypton, xenon, nitrogen, and oxygen.

  In this ion beam apparatus, any one of neon, argon, krypton, xenon, nitrogen, and oxygen is extracted from the emitter tip, and the sample can be irradiated to process the sample. In addition, one of the ion beams of hydrogen and helium can be extracted from the needle-like emitter tip to observe the sample surface. In addition, information inside the sample can be obtained by extracting electrons from the needle-shaped emitter tip and irradiating the sample with the electrons to form an image of electrons transmitted through the sample. This allows complex analysis of the sample without exposing the sample to the atmosphere.

  In the present embodiment, the objective lens 8 includes four electrodes 201, an electrode 202, an electrode 203, and an electrode 204. Each electrode is electrically insulated, and a voltage can be applied from each of the four high-voltage power supplies 301, 302, 303, and 304. The electrode 211 between the objective lens and the sample has a structure including the sample 9 therein.

  First, in order to reduce the ion energy irradiated to the sample, positive 5 kV is applied to the sample. Then, a positive 5 kV, which is the same voltage as the sample, is applied to the electrode 211 disposed between the objective lens and the sample. Here, the electrode 211 functions to substantially block the electric field from the ground potential of the vacuum chamber or the like in the space around the sample, and is substantially determined by the potential of the electrode 211 disposed between the objective lens and the sample. In this way, many of the secondary electrons emitted from the sample can be detected by the charged particle detector 11. Furthermore, in the present invention, a voltage lower than the sample voltage is applied to the electrode 211 to repel secondary electrons that have jumped out in the opposite direction to the charged particle detector so that most of them can be detected by the charged particle detector. did.

  Then, we succeeded in obtaining a clear image with a higher signal / noise ratio. At this time, when the voltage higher than the positive voltage applied to the sample is applied to the electrode 206 at the tip of the charged particle detector to maximize the collection efficiency of secondary electrons, the signal / noise ratio However, a higher and clearer image could be obtained. That is, the secondary electrons emitted from the sample are accelerated in the direction of the charged particle detector by the electric field generated by the electrode 206 at the tip of the charged particle detector, so that the collection efficiency of the secondary electrons is particularly high. That is, there is an effect that the observation / dimension measurement can be performed by increasing the signal / noise intensity ratio of the observation image. At this time, if the voltages of the electrode 211 and the objective lens electrode 203 between the objective lens and the sample are adjusted again, the secondary electron collection efficiency may be increased.

  As described above, the voltage applied to the objective lens is adjusted so that the ion beam is focused on the sample under the condition that the secondary electron collection efficiency is maximum, in other words, the image resolution is the highest. . In the present embodiment, since the sample 9 is disposed so as to be wrapped by the electrode 211, the secondary electron collecting efficiency is particularly increased.

  In this embodiment, the charged particle conversion plate 311 is disposed between the focusing lens and the objective lens. The charged particle conversion plate 311 emits secondary electrons when charged particles emitted from the sample collide. For this reason, the surface is composed of an element having an atomic number of 50 or more at least so as to increase the secondary electron emission efficiency. For example, it is made of tantalum or tungsten, or a thin film such as gold or platinum is attached to a plate material.

  Here, the acceleration voltage of the ion beam is 10 kV, and a positive 5 kV is applied to the sample. That is, the ion energy is 5 kV. Further, 7 kV is applied to the electrode 202 of the objective lens to focus on the sample. Then, positive 3 kV, which is a lower voltage than the sample, is applied to the electrode 211. In this way, most of the secondary electrons emitted from the sample return to the sample. However, the irradiated ions collide with the sample surface, and the ions reflected in the direction of the objective lens pass through the electrode 211 and the objective lens 8 and partly collide with the charged particle conversion plate 311. Here, the generated secondary electrons are detected by the upper charged particle detector 312. Then, it is possible to obtain a sample surface image whose luminance is modulated by the reflected ion intensity. This image includes information related to the element type on the sample surface.

  Next, positive 5.1 kV which is a higher voltage than the sample is applied to the electrode 211. In this way, some of the secondary electrons emitted from the sample pass through the electrode 211 and the objective lens 8. The passed secondary electrons are detected by the upper charged particle detector 312. Then, a sample surface image whose luminance is modulated by the secondary electron intensity can be obtained. This image mainly includes information related to the three-dimensional structure of the sample surface. These two types of images, that is, the reflected ion image and the secondary electron image can be stored in the main body control device 99, and an image obtained by calculating the two types of images can be displayed. For example, an image obtained by dividing a reflected ion image by a secondary electron image is an image that is sensitive to the difference in the sample surface element type. These two types of images can be selected mainly by the voltage applied to the electrode 211. It can also be obtained alternately. Needless to say, the secondary electron image may be an image acquired by the charged particle detector 11.

  Next, the acceleration voltage of the ion beam is set to 30 kV, and a positive 5 kV is applied to the sample. That is, the ion energy is 5 kV. Further, 20 kV is applied to the electrode 203 of the objective lens to focus on the sample. Then, positive 3 kV, which is a voltage lower than that of the sample, is applied to the electrode 211 to obtain a sample surface image whose luminance is modulated by the reflected ion intensity in the same manner as described above. This image contains information related to the element type on the sample surface when irradiated with an ion energy of 25 kV.

  Next, positive 5.1 kV which is a higher voltage than the sample is applied to the electrode 211. As a result, secondary electrons are detected by the upper charged particle detector 312, and a sample surface image whose luminance is modulated by the secondary electron intensity can be obtained. This image includes information mainly related to the three-dimensional structure of the sample surface when irradiated with an ion energy of 25 kV. These two types of images, that is, the reflected ion image and the secondary electron image can be stored in the main body control device 99, and an image obtained by calculating the two types of images can be displayed. For example, an image obtained by dividing a reflected ion image by a secondary electron image is an image that is sensitive to the difference in the sample surface element type. These two types of images can be selected mainly by the voltage applied to the electrode 211. It is also possible to acquire images alternately. Needless to say, the secondary electron image may be an image acquired by the charged particle detector 11.

  In the above embodiment, the tip of the emitter tip is a nanopyramid composed of atoms, a hybrid particle source for extracting an ion beam or an electron from the needle-like emitter tip, and charged particles from the hybrid particle source on the sample. Charged particle irradiation optical system for guiding the charged particles, a charged particle detector for detecting charged particles emitted from the sample, a charged particle imaging optical system for imaging charged particles that have passed through the sample, and the emitter tip A gas supply pipe for supplying a gas in the vicinity of at least one of hydrogen and helium and at least one of neon, argon, krypton, xenon, nitrogen and oxygen Two types of gas can be selected, and either a positive high voltage or a negative high voltage power supply is selected and connected to the needle-shaped emitter tip. The hybrid charged particle microscope is capable of observing the surface of the sample electrode with one of hydrogen and helium, and an ion beam of any one of neon, argon, krypton, xenon, nitrogen, and oxygen. Thus, an ion beam apparatus capable of observing the inside of the sample is provided by processing the sample, irradiating the sample with an electron beam, and detecting electrons transmitted through the sample. In particular, by using a nano pyramid emitter tip, an extremely small diameter ion beam and an extremely small diameter electron beam can be obtained, so that there is an effect that a charged particle microscope capable of analyzing sample information on a sub-nanometer order is provided.

  Furthermore, in the above embodiment, the tip of the emitter tip is a nanopyramid composed of atoms. Further, any one of neon, argon, krypton, xenon, nitrogen, and oxygen is extracted from the needle-shaped emitter tip, and the sample is irradiated with the ion beam to process the sample. Then, an ion beam of either hydrogen or helium is extracted from the needle-shaped emitter tip, the sample surface is observed, electrons are extracted from the needle-shaped emitter tip, and the sample is irradiated to pass through the sample. Sample internal information is obtained by imaging electrons. By adopting such a hybrid charged particle beam microscopy method, there is an effect that it is possible to perform a complex sample analysis that makes full use of the sample surface, sample processing, and observation inside the sample. In particular, the use of the nanopyramid emitter tip provides an effect of providing a charged particle microscope capable of analyzing sample information using an extremely small diameter ion beam and an extremely small diameter electron beam.

  In addition, at least two types of ion beams having different energies can be irradiated, a positive voltage is applied to the sample, a first electrode is provided between the electrostatic lens closest to the sample and the sample, and charged particles A second electrode different from the first electrode is arranged in front of the detector, a first voltage higher than a positive voltage applied to the sample is applied to the first electrode, and the second electrode A first observation image obtained by applying a third positive voltage higher than the voltage applied to the first electrode to the first electrode and detecting mainly secondary electrons emitted from the sample; A first voltage less than the positive voltage applied to the sample is applied to the first electrode, and a third positive voltage greater than the voltage applied to the first electrode is applied to the second electrode. A second view obtained by applying a voltage to convert positive ions reflected by the sample into electrons and detecting them. When the ion beam device is equipped with a control device capable of displaying two types of images, an image, it is possible to irradiate with different ion energy when observing, processing, and measuring with the ion beam. Similar to the effect described in Example 1, it is possible to realize ultra-high resolution observation, low damage observation, high-accuracy dimension measurement, and ultra-fine high-speed processing according to the setting conditions. Further, a first observation image obtained by detecting mainly secondary electrons emitted from the sample, and a second image obtained by detecting positive ions reflected from the sample by converting them into electrons. Since two types of observation images can be displayed, the surface element information of the sample and information relating to the state can be obtained.

  In addition, a gas field ion source capable of ionizing at least two kinds of gas, and an ion beam apparatus that irradiates a sample by focusing an ion beam emitted from the ion source with an electrostatic lens, facing the sample, An electrostatic lens closest to the sample is composed of four electrodes, and an accelerating power source that can apply two different voltages, and a voltage that differs between at least two of the four electrodes of the electrostatic lens. And a control device for storing a voltage to be applied to each electrode for at least two different acceleration voltages. The first electrode is provided between the electrostatic lens closest to the sample and the sample, the charged particle detector is disposed on the ion source side with respect to the electrostatic lens, 1 electrode applied to sample When the ion beam apparatus detects the secondary electrons emitted from the sample by the charged particle detector by applying a first voltage higher than the positive voltage, the observation, processing, and measurement are performed by the ion beam. In addition, it is possible to irradiate with changing ion energy. Similar to the effect described in the first embodiment, there is an effect that ultra-high resolution observation, low damage observation, high-accuracy dimension measurement, and ultra-fine high-speed processing can be realized by setting conditions. Furthermore, by applying a voltage higher than the positive voltage applied to the sample to the first electrode, secondary electrons emitted from the sample in a substantially vertical direction are accelerated in the direction of the ion lens. There is an effect that is suitable for efficiently detecting.

  FIG. 8 shows an example of a sample chamber internal structure of the ion beam apparatus according to the present invention. The sample chamber internal structure shown in this figure can be applied to the configuration of FIG. 1 described in the first embodiment, the configuration of FIG. 5 described in the second embodiment, and the configuration of FIG. 7 described in the third embodiment.

  In the sample chamber of this embodiment, a charged particle conversion plate 311, an upper charged particle detector 312, an objective lens 8, an electrode 211 between the objective lens and the sample, a sample 9, a sample stage 10, and a charged particle detector 11. An electron gun 16 and the like are disposed. Here, the upper charged particle detector 312 includes an electrode 226 that improves secondary electron collection efficiency, a fluorescent plate 227 that converts electrons into light, a photomultiplier tube 228 that detects light from the fluorescent plate, and the like. The electrode 226 is connected to a power source 317, and the fluorescent plate 227 is connected to a power source 318 to apply a voltage. The objective lens 8, the electrode 211 between the objective lens and the sample, the sample 9, the sample stage 10, the charged particle detector 11, the electron gun 16, and the like are the same as those in FIG.

  Also in this embodiment, the objective lens 8 includes four electrodes 201, 202, 203, and 204. Each electrode is electrically insulated, and a voltage can be applied from each of the four high-voltage power supplies 301, 302, 303, and 304. The electrode 211 between the objective lens and the sample has a structure including the sample 9 therein.

  The operation of irradiating the sample with the ion beam and detecting the secondary electrons emitted from the sample is the same as in the first embodiment. The operation of obtaining an observation image and a secondary electron image based on the reflected ion intensity using the upper charged particle detector 312 is the same as that of the third embodiment.

  In this embodiment, a method for measuring the ion intensity reflected by the sample with the charged particle detector 11 will be described.

  Here, the acceleration voltage of the hydrogen ion beam is 10 kV, and a positive 5 kV is applied to the sample. That is, the ion energy is 5 kV. 7 kV is applied to the electrode 202 of the objective lens 8. Then, positive 3 kV, which is a lower voltage than the sample, is applied to the electrode 211. Then, most of the secondary electrons emitted from the sample return to the sample. However, the irradiated ions collide with the sample surface, and some of the ions reflected toward the objective lens pass through the electrode 211, while another part collides with the electrode 211 and generates electrons. Here, the generated electrons are detected by the charged particle detector 11. Then, it is possible to obtain a sample surface image whose luminance is modulated by reflected ion intensity that hardly contains secondary electron intensity information emitted from the sample. This image includes information related to the element type on the sample surface in particular. Further, the inner surface of the electrode 211 is composed of an element having an atomic number of 50 or more at least so that the electron emission efficiency is increased. For example, it is made of tantalum or tungsten, or a thin film such as gold or platinum is attached to a plate material or vapor-deposited.

  In the configuration of the present embodiment, the intensity of the reflected ions having a small angle from the sample surface normal line and the intensity of the reflected ions having a large angle from the normal line that pass through the objective lens hole can be obtained. These two types of reflected ion intensity observation images can be stored in the main body control device 99 to display an image obtained by calculating the two types of images. It was found that using this calculation result, information on the type of sample surface element can be obtained.

  Further, in this configuration, it has been found that when the voltage of the electrode 211 is changed, the trajectory of the reflected ions changes and the energy of the reflected ions converted into electrons changes. It was also found that the contrast of the observation image is inverted depending on the voltage of the electrode 211. This indicates that there is a distribution depending on the type of element on the sample surface, and an element with a large mass is observed brightly and an element with a small mass is observed brightly. That is, it was found that the sample element analysis can be performed by changing the voltage of the electrode 211. Note that when the voltage of the electrode 211 is changed, the voltage applied to the objective lens electrode for focusing the ion beam on the sample changes. When this is obtained in advance and elemental analysis is performed, it is understood that elemental analysis can be performed with high resolution by changing the voltage applied to the objective lens electrode in conjunction with the voltage change of the electrode 211. It was.

  Next, the acceleration voltage of the hydrogen ion beam is 40 kV, and a positive 5 kV is applied to the sample. That is, the ion energy is 35 kV. A voltage of 30 kV is applied to the electrode 203 of the objective lens 8. Then, positive 3 kV, which is a lower voltage than the sample, is applied to the electrode 211. Similarly to the above, it is possible to obtain a sample surface image whose luminance is modulated by the reflected ion intensity. This image includes information related to the element type on the sample surface in particular.

  In addition, as described in Example 1, in this configuration, the secondary electrode emitted from the sample is efficiently collected when the voltage of the electrode 211 is set to the same voltage as the sample or a slightly lower voltage is applied. Can do. That is, a sample surface image whose luminance is modulated by the secondary electron intensity can be obtained. This image mainly contains information related to the three-dimensional structure of the sample surface, but two types of reflected ion intensity images and this secondary electron image are stored in the main body control device 99, and the calculated image is displayed. It can also be made.

  As described above, according to this example, by applying a positive voltage to the sample, ion energy for irradiating the sample can be lowered, the damage to the sample is reduced, and observation without changing the structure of the sample surface, It is possible to accurately measure the structural dimensions of the surface. Furthermore, since the energy of ions passing through the ion lens is high, the aberration of the ion lens is reduced, the ion beam diameter on the sample is reduced, and high-resolution observation and dimension measurement are realized.

  Further, an electrode 211 is provided between the objective lens and the sample, and by selecting a voltage to be applied to the electrode 211, an observation image based on the intensity of the ions reflected by the sample is obtained, and the secondary emitted from the sample It is possible to choose to obtain an electronic image. It is also possible to obtain a sample surface image whose brightness is modulated by the reflected ion intensity with the upper charged particle detector between the focusing lens and the objective lens, and the reflected ion intensity image obtained with the charged particle detector next to the objective lens. It is possible to perform sample element analysis by calculating For example, information on element mass can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Gas field ionization ion source, 2 ... Ion beam irradiation system column, 3 ... Sample chamber, 4 ... Cooling mechanism, 5 ... Focusing lens, 6 ... Movable aperture, 7 ... Deflector, 8 ... Objective lens, 9 ... Sample, DESCRIPTION OF SYMBOLS 10 ... Sample stage, 11 ... Charged particle detector, 12 ... Ion source evacuation pump, 13 ... Sample chamber evacuation pump, 14 ... Ion beam, 15 ... Vacuum vessel, 16 ... Electron gun, 17 ... Device mount, DESCRIPTION OF SYMBOLS 18 ... Base plate, 19 ... Anti-vibration mechanism, 20 ... Floor, 21 ... Emitter tip, 22 ... Filament, 23 ... Filament mount, 24 ... Extraction electrode, 25 ... Gas supply piping, 26 ... Gas supply mechanism, 27 ... Opening part, 28 ..., 29 ... Valve that can shut off vacuum, 35
... 1st deflector, 36 ... 2nd aperture, compressor unit 40, 61 ... Inclination mechanism, 62 ... Optical axis, 64 ... Emitter base mount, 67 ... Differential exhaust hole, 69 ... Valve which can cut off vacuum, 70 ... Non-evaporable getter material, 71 ... vacuum pump, 72 ... heating mechanism, 74 ... vacuum shuttable valve, 77 ... vacuum shuttable valve, 78 ... vacuum pump, 91 ... field ionization ion source controller, 92 ... refrigerator control 93 ... Lens control device 94 ... First aperture control device 95 ... Ion beam scanning control device 96 ... Secondary electron detector control device 97 ... Sample stage control device 98 ... Vacuum pump control device 99 ... Main body control device, 191 ... Non-evaporable getter pump control device, 192 ... Electron gun control device, 193 ... Electrode control device between objective lens and sample, 201, 202, 203 204 ... Four electrodes of objective lens, 206 ... Electrode at the tip of charged particle detector, 207 ... Phosphor, 208 ... Photomultiplier tube, 209 ... Electron emitter, 210 ... Electron irradiation electrode, 211 ... Between objective lens and sample Electrodes 301, 302, 303, 304... Four power sources for applying voltage to the objective lens, 305... Sample application power source, 306... Electrode application power source disposed between the objective lens and the sample, 307. Power supply for electrode application at the tip of the particle detector, 308... Phosphor application power, 309... Electron etta application power, 310.

Claims (6)

A gas field ion source that controls an ion beam emitted from the emitter tip; an irradiation optical system that irradiates the sample with the ion beam from the gas field ion source; and the ion beam. In an ion beam apparatus having a charged particle detector for detecting charged particles resulting from irradiation of the sample, and an electrostatic lens having at least first to fourth electrodes and closest to the sample,
The distance between the sample and the first electrode closest to the sample is such that the distance between the first electrode and the second electrode closest to the sample is the first distance between the first electrode and the first electrode closest to the sample. An ion beam apparatus characterized in that the distance is equal to or less than a distance including a thickness. The ion beam apparatus according to claim 1.
A fifth electrode provided between the electrostatic lens and the sample, to which a first positive voltage is applied;
A first power source for applying a second positive voltage different from the first positive voltage to the sample or the sample stage so as to generate an electric field gradient between the sample and the second electrode; An ion beam device characterized by. The ion beam apparatus according to claim 1.
An ion beam apparatus comprising: second to fourth power supplies so that different voltages can be applied to the first to fourth electrodes, respectively. The ion beam apparatus according to claim 1.
A fifth electrode provided between the electrostatic lens closest to the sample and the sample, to which a first positive voltage is applied;
A power source for the sample for applying a second positive voltage to the sample or the sample stage;
A sixth electrode provided near the detection surface of the charged particle detector and to which a third positive voltage is applied;
The sample was irradiated when the first positive voltage was higher than the second positive voltage and the third positive voltage was set higher than the first positive voltage. A first observation image obtained by detecting secondary electrons among the charged particles resulting from the above, and the second positive voltage is higher than the first positive voltage, and the first positive image A second observation image obtained by detecting reflected charged particles among charged particles resulting from irradiation of the sample when the third positive voltage is set higher than the voltage of And a display unit for displaying the ion beam apparatus. The ion beam apparatus according to claim 1.
An ion beam apparatus characterized in that a third distance between a third electrode third closest to the sample and a fourth electrode fourth closest to the sample is smaller than a thickness of the fourth electrode. . The ion beam apparatus according to claim 1.
The distance between the sample and the first electrode closest to the sample is smaller than the second distance between the second electrode closest to the sample and the third electrode closest to the sample. An ion beam device characterized by.

Images