Patent Application
20150213999
The present invention relates to a charged particle beam apparatus capable of observing a sample in a gas atmosphere at atmospheric pressure or at a predetermined pressure.
Scanning electron microscopes (SEM) or transmission electron microscopes (TEM) are used to observe infinitesimal regions of an object. Generally, these devices evacuate an enclosure that houses a sample to get images of the sample in a vacuum state. However, biochemical samples or liquid samples can be damaged in vacuum or can be changed in nature therein. Meanwhile, there has been a strong need for observing such samples under electron microscope. In recent years, there have been developed SEM equipment and sample holding devices that allow an observation target sample to be observed at atmospheric pressure.
In principle, these devices set up a permeable diaphragm or a tiny through hole that allows an electron beam to pass therethrough between an electron optical system and the sample, thereby separating the vacuum state from the atmospheric state. Common to these devices is the provision of the diaphragm between the sample and the electron optical system.
For example, Patent Document 1 discloses an SEM in which an electron optical tube has its electron source oriented downward and its objective lens oriented upward. The end of the electron optical tube emitting an electron beam has a diaphragm with an O-ring allowing the electron beam to pass through an emitting hole of the tube. According to the invention described in this literature, the observation target sample is directly placed on the diaphragm. The sample is then irradiated from below with a primary electron beam so that reflected or secondary electrons are detected for SEM observation. The sample is held in a space made up of the diaphragm and a circular member surrounding the diaphragm. Furthermore, this space is filled with liquid such as water.
The ordinary charged particle beam apparatuses have been manufactured so as to be dedicated to making observations in a gas atmosphere at atmospheric pressure or at a pressure substantially equal thereto. There have existed no devices capable of simply making observations under an ordinary high-vacuum charged particle microscope in a gas atmosphere at atmospheric pressure or at a pressure approximately equal thereto.
For example, the SEM described in Patent Document 1 is a very special device in structural terms. The device is incapable of making SEM observations in the ordinary high-vacuum atmosphere.
Moreover, methods of the existing technology are based on the assumption that signals are detected in a state where the diaphragm and the sample are positioned close to each other. For this reason, the existing device structure is not suitable for observing, say, a sample with a prominently uneven surface.
The present invention has been made in view of the above circumstances and provides a charged particle beam apparatus that permits observation of the sample in an air atmosphere or in a gas atmosphere without significantly changing the structure of the existing high-vacuum charged particle microscope, the charged particle beam apparatus being further capable of observing an uneven sample.
To solve the above-described problem, there may be adopted, for example, the structures described in the appended claims of this application.
This application includes multiple means for solving the above-described problem, one such means including: a charged particle optical tube that irradiates a sample with a primary charged particle beam; a vacuum pump that evacuates the inside of the charged particle optical tube; a diaphragm arranged to separate a space in which the sample is placed from the charged particle optical tube, the diaphragm being detachable and allowing the primary charged particle beam to permeate or pass therethrough; and a detector that detects secondary particles discharged from the sample being irradiated with the primary charged particle beam. The detector is installed in the space where the sample is placed.
According to the present invention, there is provided a charged particle beam apparatus that permits observation of the sample in an air atmosphere or in a gas atmosphere without significantly changing the structure of the existing high-vacuum charged particle microscope. The charged particle beam apparatus is further capable of observing a sample having an uneven surface.
Further problems, structures, and advantages other than those stated above will become apparent upon a reading of the ensuing explanation of some embodiments of the present invention.
Some embodiments of the present invention will now be explained with reference to the accompanying drawings.
What follows is an explanation of charged particle beam microscopes as an example of the charged particle beam apparatus. It should be noted that these microscopes are only an example embodying the present invention and that the invention is not limited to the embodiments to be discussed hereunder. The present invention can be applied to scanning electron microscopes, scanning ion microscopes, scanning transmission electron microscopes, a composite device that combines any of these microscopes with sample processing equipment, or analyzer/inspection equipment that applies any of these microscopes.
In this description, the wording “atmospheric pressure” refers to an air atmosphere or a predetermined gas atmosphere and signifies a pressure environment under atmospheric pressure or in a somewhat negatively or positively pressured state. Specifically, the environment is to be at about 105 Pa (atmospheric pressure) to about 103 Pa.
The first embodiment is explained here as the basic mode for carrying out the invention.
The charged particle optical tube 2 is made up of such elements as a charged particle source 8 that generates a charged particle beam, and an optical lens 1 that focuses the generated charged particle beam at the bottom of the tube as a primary charged particle beam for scanning the sample 6. The charged particle optical tube 2 is positioned in a manner protruding into the first enclosure 7 and fixed to the first enclosure 7 by means of a vacuum sealing member 123. The tip of the charged particle optical tube 2 has a detector 3 that detects secondary particles (secondary or reflected electrons, secondary charged particles such as ions, photons, X-rays, etc.) generated by irradiation with the primary charged particle beam. In the second enclosure 121, i.e., in the space where the sample is placed, there is installed a detector 151 capable of detecting secondary particles as will be discussed later.
The charged particle microscope of the first embodiment has the control system that includes a computer 35 used by an apparatus user, a master control unit 36 connected with the computer 35 to conduct communications, and a slave control unit 37 that controls an evacuation system and a charged particle optical system, among others, under instructions from the master control unit 36. The computer 35 has a monitor that displays an apparatus operation screen (GUI) and input means such as a keyboard and a mouse for making entries into the operation screen. The master control unit 36, slave control unit 37 and computer 35 are interconnected by communication lines 43 and 44.
The slave control unit 37 is a unit that sends and receives control signals for controlling the vacuum pump 4, charged particle source 8, and optical lens 1. Also, the slave control unit 37 converts the output signal from the detector 3 into a digital image signal before transmitting the signal to the master control unit 36. In
In the master control unit 36 and slave control unit 37, both analog and digital circuits may coexist. The master control unit 36 and slave control unit 37 may alternatively be unified into a single unit. It should be noted that the structure of the control system shown in
The first enclosure 7 is connected with vacuum piping 16 of which one end is coupled to the vacuum pump 4, so that the inside of the first enclosure 7 is kept in a vacuum state. Also, the first enclosure 7 has a leak valve 14 that exposes the enclosure interior to the atmosphere. At the time of maintenance, the leak valve 14 can expose the inside of the first enclosure 7 to the atmosphere. Installation of the leak valve 14 is optional. There may be two or more leak values 14 installed. Installation of the leak valve 14 on the first enclosure 7 is not limited to the location shown in
The second enclosure 121 is composed of a cuboid-shaped main unit 131 and a matching unit 132. At least one side of the main unit 131 as the cuboid is an open side 9, as will be discussed later. Except for one of the sides of the cuboid-shaped main unit 131 to which a diaphragm holding member 155 is attached, the sides of the main unit 131 may be formed by the walls of the second enclosure 121. Alternatively, the second enclosure 121 may be devoid of its own walls. Instead, the second enclosure 121 may be formed by the sidewalls of the first enclosure 7 into which the second enclosure 121 is built. The second enclosure 121 is positionally fixed to the sidewalls or inner wall surfaces of the first enclosure 7 or to the charged particle optical tube. The main unit 131 is inserted into the first enclosure 7 through the above-mentioned opening. In its built-in state, the main unit 131 has the function of storing the sample 6 to be observed. The matching unit 132 has a matching surface against the outer wall surface of the side on which the opening of the first enclosure 7 is provided, and is fixed to that outer wall surface by means of a vacuum sealing member 126. In this manner, the second enclosure 121 as a whole is fit into the first enclosure 7. The above-mentioned opening is formed most simply by utilizing the opening that is intrinsically provided to the vacuum sample chamber of the charged particle microscope and is used for bringing in and out the sample. That is, the second enclosure 121 may be manufactured in a manner conforming to the size of the existing hole of which the circumference may be furnished with the vacuum sealing member 126. As a result, the effort to remodel the apparatus can be minimized. Also, the second enclosure 121 may be detached from the first enclosure 7.
The upper surface side of the second enclosure 121 is provided with a diaphragm 10 that is positioned immediately under the charged particle optical tube 2 when the entire second enclosure 121 is fit into the first enclosure 7. Also, the upper part of the second enclosure 121 is furnished with the detector 151. The diaphragm 10 allows the primary charged particle beam discharged from the lower end of the charged particle optical tube 2 to permeate or pass therethrough. Past the diaphragm 10, the primary charged particle beam ultimately reaches the sample 6.
In the past, the sample was held in a liquid-filled space inside of the diaphragm. Once the sample was observed in the atmosphere, the sample became wet so that it was very difficult to observe the sample in the same state in both the air atmosphere and the high-vacuum atmosphere. Another problem was that since the diaphragm was always in contact with liquid, the diaphragm was highly liable to break. By contrast, the method of the first embodiment involves keeping the sample 6 out of contact with the diaphragm 10 so that the sample can be observed in both the high-vacuum atmosphere and the air atmosphere without changing its state. Furthermore, the diaphragm is less likely to break because the sample is not placed thereon.
Having reached the sample 6, the charged particle beam causes secondary particles such as reflected or permeated charged particles to be discharged from the surface or from inside of the sample. The detector 3 or 151 detects the secondary particles. The detector 3 is located in a space above the diaphragm to which the charged particles are emitted. The detector 151 is positioned approximately on the same plane as the lower side surface of the diaphragm.
The detectors 3 and 151 are each a detecting element capable of detecting charged particle beams emitted with several to tens of KeV of energy. The detecting elements may also be provided with signal amplifying means. In view of the requirements of the apparatus configuration, the detecting elements should preferably be shaped thin and flat. For example, the detecting elements may be semiconductor detectors made of a semiconductor material such as silicon, or may be scintillators capable of converting charged particle signals into light internally or by use of their glass surfaces.
Where the charged particle beam is an electron beam, the diaphragm 10 needs to be thin enough to let the electron beam permeate, typically several nm to less than 20 μm in thickness. In place of the diaphragm, there may be provided an aperture member having a hole that lets the primary charged particle beam pass therethrough. In this case, the hole should preferably be 1 mm2 or less in area in view of the requirement that a commonly available vacuum pump be capable of differential evacuation. Where the charged particle beam is an ion beam, an aperture with an area of less than about 1 mm2 is used because the penetration is difficult to achieve without damaging the diaphragm. A dashed line in
As shown in
According to the existing techniques such as the environmental cell that can locally maintain an air atmosphere, it is possible to observe the sample in an air or gas atmosphere only if the sample is small enough to be inserted into the cell. Larger samples cannot be observed in the air/gas atmosphere. Moreover, in the case of the environmental cell, observing different samples requires performing a troublesome sample replacement procedure. That is, the environmental cell is required to be extracted from the vacuum sample chamber of the SEM and, with the current sample replaced by a new sample, again brought into the vacuum sample chamber. By contrast, according to the method of the first embodiment, one side of the second enclosure 121 is left open so that the sample 6 as large as a semiconductor wafer can be placed in the second space 12 constituting an extensive atmospheric pressure space for observation under atmospheric pressure. In particular, the second enclosure of the first embodiment can be easily made large in size because it is configured to be inserted laterally into the sample chamber. A sample too large to be placed into the environmental cell can thus be observed. Furthermore, the second enclosure 121 has the open side that allows samples to be switched easily between the inside and the outside of the second space 12 during observation.
The base 159 furnished with the diaphragm 10 is detachable from the diaphragm holding member 155. Where the base 159 fitted with the diaphragm 10 is in place, the diaphragm holding member 155 is allowed to be detached. If the diaphragm 10 is damaged upon contact with the sample 6 for example, the entire diaphragm holding member 155 can be removed from the apparatus for easy replacement of the diaphragm 10. Although not shown, the diaphragm holding member 155 may be connected to the second enclosure 121 with screws or the like.
The detector 151 is installed in a manner surrounding the diaphragm 10. A signal detected by the detector 151 is output to the signal amplifier 153 via a signal line 156. In
a) shows the structure surrounding the diaphragm 10 and detector 151. The diaphragm 10 is mounted on the base 159. The diaphragm 10 is made of a carbon material, an organic material, silicon nitride, silicon carbide, or silicon oxide. The base 159 is a member made of silicon for example, and has a tapered hole 165 formed typically by wet etching as illustrated. The diaphragm 10 is positioned at the bottom as shown in
b) and 3(c) show how the base 159, positioned on the diaphragm holding member 155, is fitted with the diaphragm 10 and the detector 151 capable of detecting the charged particle beam. These drawings are perspective views seen from the side of the sample 6. The detector 151 is installed in a manner surrounding the diaphragm. Although not shown, the diaphragm holding member 155 equipped with the detector 151 and the base 159 fitted with the diaphragm 10 are bonded together with an adhesive or double-sided tape capable of vacuum sealing. A sectional view of this assembly is as shown in
Here, the surface of the diaphragm 10 and the detecting surface of the detector 151 should preferably be positioned approximately on the same plane. For example, a dotted line 176 in
The detector 151 is a semiconductor detection element made of silicon, for example. Upon receipt of the charged particle beam or the like, the semiconductor detection element amplifies signals and generates a current. This current is output to a connector 160 via a signal line 162.
The detector 151 may be provided not in one piece but in multiple parts (e.g., 4 parts) as shown in
d) shows an example in which the diaphragm holding base and the detector are integrally formed. If the base 159 and the detector 151 are both made of silicon to constitute a semiconductor detector, it is possible to simultaneously manufacture, during the semiconductor process, a holding stand 177 fitted with the diaphragm 10 and the detecting element 151. A signal detected by the detector 151 is output to a pad 164 made of a metal via the signal line 162. The pad 164 may be connected to the signal amplifier 153 via a wire bonding or connector arrangement. As shown in
f) is a sectional view of the setups in
The detector 151 may also be a scintillator that converts the charged particle beam to light. The scintillator first converts the charged particle beam to light. In this case, the signal line 162 is not an electrical signal line but a light wave channel, and the connector 160 is an optical transmission connector. Also, the detector 151 may not be limited to a connector that detects the charged particle beam such as ions and electrons but may be a connector that detects photons or X-rays discharged from the sample. As another alternative, the detector 151 may be a multi-channel plate, an ionization chamber, or some other detector. As long as it satisfies the functions intended by the first embodiment, the detector falls within the scope of the charged particle beam microscope of the first embodiment.
Explained next with reference to
a) shows how the diaphragm 10 and the sample 6 come close to each other. Where the diaphragm 10 and the sample 6 are positioned close to each other, the secondary particles generated by the charged particle beam being emitted to the sample can reach the detector 3. Whereas the clearance between the diaphragm 10 and the sample 6 is in an atmospheric state, if it is desired to minimize the scattering of the charged particle beam, i.e., if it is desired to minimize the spot diameter of the charged particle beam in order to improve resolution, then bringing the sample 6 close to the diaphragm 10 in this manner is effective.
On the other hand, if it is desired to observe a sample with a prominently uneven surface such as one shown in
It may be determined to use one or both of the detectors depending on the distance between the diaphragm and the sample and control the ON/OFF of each of the detectors accordingly. Alternatively, both detectors may always be used to detect secondary particles.
It may seem that the detector 151 is not necessary if the diaphragm 10 has a sufficiently wide area. However, the diaphragm is made thin enough to let the charged particle beam permeate therethrough, so that enlarging the area of the diaphragm is extremely difficult. For this reason, when a sample with an uneven surface is to be observed, it is preferred to position the detector 151 in the vicinity of the diaphragm 10.
As explained above, the first embodiment brings about a charged particle microscope capable of observing uneven samples at atmospheric pressure.
The second embodiment is explained below as another application of the present invention to the charged particle microscope. Specific examples of the charged particle microscope include scanning electron microscope and ion microscopes. In the ensuing paragraphs, the portions of the second embodiment similar to those of the first embodiment will not be discussed further.
The diaphragm holding member 155 is detachably fixed to the lower surface side of the ceiling board of the second enclosure 121 with a vacuum sealing member interposed therebetween. The diaphragm 10 is made as thin as several nm to tens of μm for allowing the electron beam to permeate therethrough. Being formed very thin, the diaphragm 10 can break over time or during preparation of observation. Also, the diaphragm 10 is so thin that it is very difficult to handle directly. Because the second embodiment allows the diaphragm 10 to be handled not directly but by means of the diaphragm holding member 155, it is appreciably easy to deal with the diaphragm 10 (especially its replacement). That is, when the diaphragm 10 is broken, it may be replaced altogether with the diaphragm holding member 155. In case only the diaphragm 10 needs to be replaced, the diaphragm holding member 155 may be first detached from the apparatus and then the diaphragm 10 may be replaced outside the apparatus. As with the first embodiment, an aperture member having a hole about 1 mm2 or less in area may alternatively substitute for the diaphragm. And as explained above with reference to
A detection signal from the detector 151 is sent to a slave control unit 37 via a hermetic connector 175 attached to a cover part 122 past a signal amplifier 153. Since a second space 12 inside the second enclosure may be brought into a vacuum state as will be discussed later, the hermetic connector 175 should preferably be a vacuum-sealed hermetic connector capable of maintaining the vacuum region inside. Although the signal amplifier 153 is shown installed in the second space 12 in the drawing, the signal amplifier 153 may alternatively be installed outside (in the air atmosphere) or in a first space as a vacuum space.
In the case of the charged particle microscope as the second embodiment, the open side of the second enclosure 121 can be covered with the cover part 122, so that various functions may be implemented. These functions are explained below.
The charged particle microscope of the second embodiment has the function of feeding a shift gas other than the air into the second enclosure. The charged particle beam discharged from the lower end of the charged particle optical tube 2 passes through the first space 11 maintained in a high-vacuum state to permeate the diaphragm 10 shown in
For the above reasons, the charged particle microscope of the second embodiment has the cover part 122 having an attaching part (gas introduction part) for a gas feed pipe 100. The gas feed pipe 100 is coupled to a gas cylinder 103 via a coupling portion 102, which allows a shift gas to be introduced into the second space 12. Halfway along the gas feed pipe 100, there is provided a gas control valve 101 that controls the flow rate of the shift gas flowing through the pipe. For control purposes, a signal line is extended from the gas control valve 101 to the slave control unit 37. The apparatus user can control the flow rate of the shift gas through an operation screen displayed on the monitor of a computer 35.
Since the shift gas is a light element gas, it tends to stay in the upper region of the second space 12; it is difficult to fill the lower region of the second space 12 with the shift gas. This bottleneck may be bypassed by providing the cover part 122 with an opening for communicating the inside and the outside of the second space at a location lower than the mounting position of the gas feed pipe 100. In
A vacuum evacuation port may be provided on the second enclosure 121 or cover part 122 to once evacuate the second enclosure 121 so that a slightly negative pressure is generated therein. In this case, low-vacuum evacuation instead of high-vacuum evacuation is sufficient because the atmospheric gas components residing inside the second enclosure need only be reduced to a predetermined level or lower. Following low-vacuum evacuation, gas may be introduced through the gas feed pipe 100. The degree of vacuum involved is from 105 Pa to 103 Pa or thereabout. If gas is not to be introduced, the gas cylinder 103 may be replaced with a vacuum pump to generate a slightly negative pressure inside.
In the ordinary, so-called low-vacuum scanning electron microscope, the electron beam column communicates with the sample chamber. It follows that lowering the degree of vacuum in the sample chamber close to atmospheric pressure entails varying the pressure inside the electron beam column correspondingly. It has been difficult to control the sample chamber to pressures ranging from about 105 Pa (atmospheric pressure) to about 103 Pa. According to the second embodiment, by contrast, the diaphragm isolates the second space from the first space, so that the pressure and type of the gas in the second space enclosed by the second enclosure 121 and cover part 122 can be freely controlled. This makes it possible to control the sample chamber to pressures ranging from about 105 Pa (atmospheric pressure) to about 103 Pa—something that has been difficult to achieve in the past. Moreover, the state of the sample can be observed not only at atmospheric pressure (about 105 Pa) but also under continuously varying pressures close thereto.
However, if the sample is a biological sample or the like that contains moisture, the contained moisture evaporates once the sample is placed in a vacuum state so that the state of the sample is changed. In this case, a shift gas should preferably be introduced directly from the air atmosphere as explained above. When the above-mentioned opening is closed with the cover part following introduction of the shift gas, the shift gas may be effectively contained within the second space 12.
If a three-way valve is attached to the location of the above-mentioned opening, this opening may double as a rough exhaust port and an air leak exhaust port. Specifically, one port of the three-way valve is coupled to the cover part 122, another port to a vacuum pump for rough exhaust, and another port to a leak valve. The dual-purpose exhaust port mentioned above can be implemented in this manner.
In place of the opening above, the pressure regulating valve 104 may be provided. The pressure regulating valve 104 has the function of automatically opening if the pressure inside the second enclosure 121 becomes higher than atmospheric pressure. If the internal pressure gets higher than atmospheric pressure during introduction of a light element gas, the pressure regulating valve having this function automatically opens to release the atmospheric gas components such as nitrogen and oxygen into the outside of the apparatus and thereby fill the inside of the apparatus with the light element gas. Incidentally, the gas cylinder 103 shown in the drawing may be attached to the charged particle microscope either during manufacturing or later by the apparatus user.
How to adjust the position of the sample 6 is explained next. The charged particle microscope of the second embodiment has a sample stage 5 as a means for moving the field of observation. The sample stage 5 is provided with an X-Y drive mechanism for movement in the plane direction and a Z-axis drive mechanism for movement in the height direction. The cover part 122 is furnished with a support plate 107 that serves as a base plate for supporting the sample stage 5. The sample stage 5 is fixed to the support plate 107. The support plate 107 is installed in such a manner as to extend toward the opposite surface of second enclosure 121 from the cover part 122 and into the inside of the second enclosure 121. Support shafts extend from the Z-axis drive mechanism and X-Y drive mechanism, each of the shafts being coupled with operation knobs 108 and 109. By manipulating the operation knobs 108 and 109, the apparatus user adjusts the position of the sample 6 inside the second enclosure 121.
The mechanisms for replacing the sample 6 are explained next. The charged particle microscope of the second embodiment has a cover part support member 19 and a base plate 20 installed under the bottom of the first enclosure 7 and under the lower surface of the cover part 122, respectively. The cover part 122 is detachably fixed to the second enclosure 121 with a vacuum sealing member 125 interposed therebetween. The cover part support member 19 is also fixed detachably to the base plate 20. As shown in
The base plate 20 is provided with a support rod 18 for use as a guide upon removal. In the normal state of observation, the support rod 18 is housed in a storage part of the base plate 20. The support rod 18 is structured to extend in the direction in which the cover part 122 is drawn out for removal. Also, the support rod 18 is fixed to the cover part support member 19 so that when the cover part 122 is removed from the second enclosure 121, the cover part 122 will not be completely detached from the body of the charged particle microscope. This arrangement is intended to prevent the sample stage 5 or the sample 6 from falling.
Where to set up the signal amplifiers and the output signal lines extending therefrom, and how to wire and how to attach and detach these components will fall within the scope of the charged particle microscope of the second embodiment as long as these arrangements and methods satisfy the functions intended by the second embodiment.
When the sample is to be brought into the second enclosure 121, the operation knob for the Z-axis of the sample stage 5 is first operated to move the sample 6 away from the diaphragm 10. The pressure regulating valve 104 is then opened to expose the inside of the second enclosure to the atmosphere. Thereafter, following the verification that the inside of the second enclosure is neither in a negative pressure state nor in an inordinately pressured state, the cover part 122 is drawn out to the opposite side of the apparatus body. If the signal amplifier 153 is connected by wire with the hermetic connector 175, the wiring is detached as needed. This brings about the state in which the sample 6 can be replaced. After the sample is replaced, the signal amplifier 153 is electrically reconnected with the hermetic connector 175 as needed; the cover part 122 is pressed into the second enclosure 121; the cover part 122 is fixed to the matching unit 132 using a fastening member, not shown; and a shift gas is introduced as needed. The above operations may also be carried out while a high voltage is being applied to an optical lens 2 inside the charged particle optical tube 2 or while the charged particle beam is being discharged from the charged particle source 8. This means that the above operations can be performed while the charged particle optical tube 2 is allowed to operate continuously, with the first space kept in the vacuum state. The charged particle microscope of the second embodiment thus permits observation to be started quickly after the sample is replaced.
The charged particle microscope of the second embodiment may also be used as an ordinary high-vacuum SEM.
As explained above, the second embodiment has the sample stage 5, sample stage operation knobs 108 and 109, gas feed pipe 100, and pressure regulating valve 104 attached altogether to the cover part 122. As a result, the apparatus user can remain facing the same side of the first enclosure while manipulating the operation knobs 108 and 109 or working to replace the sample or to attach and detach the gas feed pipe 100 and pressure regulating valve 104. It follows that, compared with the ordinary charged particle microscope in which the above-mentioned components are mounted in a scattered manner on various sides of the sample chamber, the second embodiment offers appreciably enhanced operability when the state for observation at atmospheric pressure is switched with the state for observation in a high vacuum.
In addition to the secondary electron detector and the reflected electron detector, there may be provided an X-ray detector and a photodetector capable of EDS analysis and fluorescence line observation. The X-ray detector and photodetector may be installed in either the first space 11 or the second space 12.
A voltage may be applied to the sample stage 5 and detector 151. Applying the voltage to the sample stage 5 and detector 151 gives high energy to the emission and transmission electrons emanating from the sample 6, which can increase the amount of signals and thereby improve the S/N ratio of images.
As described above, the second embodiment supplements the effects of the first embodiment by acting as a high-vacuum SEM capable of making observations in a gas atmosphere at atmospheric pressure or at a slightly negative pressure. Because the second embodiment permits observation by letting the shift gas be introduced, the charged particle microscope of the second embodiment permits acquisition of images with a higher S/N ratio than the charged particle microscope of the first embodiment.
Although the second embodiment has been explained above with emphasis on a structure intended for use as a desktop electron microscope, the second embodiment may also be applied to a large-scale charged particle microscope. Whereas the desktop electron microscope has the entire apparatus or its charged particle optical tube supported by an enclosure on an apparatus installation surface, the large-scale charged particle microscope need only have the entire apparatus placed on a frame. Thus when the first enclosure 7 is placed on the frame, the structure discussed above in connection with the second embodiment can be applied unmodified to the large-scale charged particle microscope.
The third embodiment is explained below in conjunction with a structure in which the cover part 122 is removed from the apparatus structure shown in
In the structure shown in
The fourth embodiment is a variation of the apparatus structure shown in
The second enclosure 121 is vacuum-sealed to the charged particle optical tube 2 by means of the vacuum sealing member 123. Furthermore, the second enclosure 121 is vacuum-sealed to the first enclosure 7 using a vacuum sealing member 129. This structure provides a larger second space 12 than the structure shown in
The present invention is not limited to the embodiments discussed above and may also be implemented in diverse variations. The embodiments above have been explained as detailed examples helping this invention to be better understood. The present invention, when embodied, is not necessarily limited to any embodiment that includes all the structures described above. Part of the structure of one embodiment may be replaced with the structure of another embodiment. The structure of a given embodiment may be supplemented with the structure of another embodiment. Part of the structure of each embodiment may be supplemented with, emptied of, or replaced by another structure. The above-described structures, functions, processing units, and processing means may be implemented partially or entirely by hardware through integrated circuit design, for example. Also, the above-described structures and functions may be implemented by software in the form of programs which, when interpreted and executed by a processor, bring about the respective functionality.
The programs, tables, files, and other data for implementing the functions may be stored in storage devices such as memories, hard disks and SSD (Solid State Drive), or on recording media such as IC cards, SD cards and DVDs.
The illustrated control lines and data lines may not represent all control lines and data lines needed in the apparatus as a product. In practice, almost all structures may be considered to be interconnected.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-213382 | Sep 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/067967 | 7/1/2013 | WO | 00 |
