JP2016122668A - Charged particle beam device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam device or a charged particle microscope which allows a user to observe an observation sample in an air atmosphere or a gas atmosphere, without significantly changing a configuration of a conventional high-vacuum charged particle microscope.SOLUTION: A charged particle beam device adopts a thin film for separating a vacuum atmosphere from an air atmosphere (or a gas atmosphere). An attachment capable of holding the thin film and keeping the interior in the air atmosphere or the gas atmosphere is inserted into and used in a vacuum sample chamber of a high-vacuum charged particle microscope. The attachment is vacuum-sealed and fixed to a vacuum partition wall of the vacuum sample chamber. Image quality is further improved by replacing the interior of the attachment with light-element gas, such as helium, nitrogen or water vapor, which has a mass lighter than that of atmospheric gas.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a microscope technique capable of observing a sample to be observed in atmospheric pressure or a predetermined gas atmosphere, and more particularly to a desktop charged particle microscope.

  In order to observe a minute region of an object, a scanning electron microscope (SEM), a transmission electron microscope (TEM), or the like is used. Generally, in these apparatuses, the second casing for placing the sample is evacuated, and the sample atmosphere is evacuated to image the sample. On the other hand, there is a great need for observing a sample such as a biochemical sample or a liquid sample that is damaged by a vacuum or whose state changes with an electron microscope. In recent years, an SEM device or a sample holding device that can observe an observation target sample at atmospheric pressure Etc. are being developed.

  In principle, these devices provide a thin film or minute through-hole that can transmit an electron beam between the electron optical system and the sample to partition the vacuum state from the atmospheric state. This is common in that a thin film is provided between the two.

  For example, in Patent Document 1, an electron source side of an electron optical column is disposed downward and an objective lens side is disposed upward, and an electron beam is placed on an electron beam exit hole at the end of the electron optical column via an O-ring. An atmospheric pressure SEM provided with a thin film capable of transmitting is disclosed. In the invention described in the document, an observation target sample is placed directly on a thin film, and a primary electron beam is irradiated from the lower surface of the sample to detect reflected electrons or secondary electrons and perform SEM observation. The sample is held in a space constituted by an annular member and a thin film installed around the thin film, and the space is filled with a liquid such as water. By the invention disclosed in Patent Document 1, an atmospheric pressure SEM particularly suitable for observation of a biological sample is realized.

  In Patent Document 2, an observation sample is stored in a petri dish-like cylindrical container provided with an aperture on the upper surface side through which an electron beam passes, and this cylindrical container is provided in a vacuum sample chamber of an SEM, and further, An invention of an environmental cell is disclosed in which a hose is connected from the outside of the vacuum sample chamber so that the interior of the container can be maintained in a pseudo atmosphere. Here, “pseudo” means that, when the vacuum sample chamber is evacuated, gas flows out from the aperture, so strictly speaking, observation is not performed under an atmospheric pressure environment.

JP 2009-158222 A (US Patent Publication No. 2009/0166536) JP 2009-245944 A (US Patent Publication No. 2009/0242763)

  Conventional charged particle microscopes or charged particle beam devices equipped with an observation function in a gas atmosphere are all devices specially manufactured for observation in a gas atmosphere. There has been no apparatus that can easily perform observation under the atmospheric pressure / gas atmosphere.

  For example, the atmospheric pressure SEM described in Patent Document 1 is a structurally very special device, and SEM observation in a normal high vacuum atmosphere cannot be performed. In addition, the observation object is held inside a thin film filled with liquid, and once the atmospheric pressure observation is performed, the sample gets wet, so it is not possible to observe the sample in the same state in both an air atmosphere and a high vacuum atmosphere. It is very difficult. Moreover, since the liquid is always in contact with the thin film, there is also a problem that the possibility that the thin film is damaged is very high.

  Although the environmental cell described in Patent Document 2 can be observed in an atmospheric pressure / gas atmosphere, only a sample of a size that can be inserted into the cell can be observed, and in an atmospheric pressure / gas atmosphere of a large sample. There is a problem that it cannot be observed. In the case of an environmental cell, in order to observe a different sample, the environmental cell must be taken out from the vacuum sample chamber of the SEM, the sample must be replaced, and loaded again into the vacuum sample chamber. is there.

  The present invention has been made in view of such problems, and a charged particle beam capable of observing a sample to be observed in an air atmosphere or a gas atmosphere without greatly changing the configuration of a conventional high-vacuum charged particle microscope. An object is to provide an apparatus or a charged particle microscope.

  In the present invention, an attachment capable of storing the sample is inserted into the vacuum chamber provided in the charged particle microscope from the opening of the vacuum chamber while maintaining an internal pressure higher than the pressure in the vacuum chamber. However, the above-mentioned problem is solved by fixing the vacuum chamber to use. The opening part of a vacuum chamber is provided in the side surface or bottom face of the said vacuum chamber, for example. Further, the above attachment has a function of holding a thin film that allows the primary charged particle beam to pass through or pass through the inside of the attachment, thereby ensuring a pressure difference between the vacuum chamber and the inside of the attachment. The vacuum chamber may be called a first casing, and the attachment may be called a second casing for the vacuum chamber.

  While the vacuum chamber is maintained at a high vacuum by the thin film, the interior of the attachment is maintained at an atmospheric pressure / gas atmosphere. In addition, the observation sample can be carried in and out between the inside and outside of the attachment. That is, according to the present invention, it is possible to realize a charged particle microscope in which observation in an atmospheric pressure / gas atmosphere can be realized more simply than before.

  Further, since the attachment of the present invention is inserted from the side of the sample chamber, it can be easily increased in size, so that even a large sample that cannot be enclosed in an environmental cell can be observed.

1 is an overall configuration diagram of a charged particle microscope according to Embodiment 1. FIG. FIG. 3 is an overall configuration diagram of a charged particle microscope according to a second embodiment. The figure which shows the charged particle microscope of Example 2 of the state which pulled out the board member. The figure which shows the charged particle microscope of Example 2 of the state used as a high vacuum SEM. FIG. 9 is an operation explanatory diagram of the charged particle microscope according to the second embodiment. 4 is a configuration example of a charged particle microscope of Example 2. FIG. 4 is a configuration example of a charged particle microscope of Example 2. FIG. 4 is a configuration example of a charged particle microscope of Example 2. FIG. FIG. 5 is an overall configuration diagram of a charged particle microscope according to a third embodiment. FIG. 6 is an overall configuration diagram of a charged particle microscope according to a fourth embodiment. FIG. 6 is an overall configuration diagram of a charged particle microscope of Example 5.

  Each embodiment will be described below with reference to the drawings.

  In this example, the most basic embodiment will be described. FIG. 1 shows an overall configuration diagram of the charged particle microscope of the present embodiment. The charged particle microscope shown in FIG. 1 is mainly inserted into a charged particle optical column 2, a first casing (vacuum chamber) 7 that supports the charged particle optical column with respect to the apparatus installation surface, and the first casing 7. The second housing (attachment) 121 used in this manner and a control system for controlling them. When the charged particle microscope is used, the charged particle optical column 2 and the inside of the first housing are evacuated by the vacuum pump 4. The start / stop operation of the vacuum pump 4 is also controlled by the control system. Although only one vacuum pump 4 is shown in the figure, two or more vacuum pumps may be provided.

  The charged particle optical column 2 is an element such as a charged particle source 0 that generates a charged particle beam, an optical lens 1 that focuses the generated charged particle beam and guides it to the lower part of the column and scans the sample 6 as a primary charged particle beam. Consists of. The charged particle optical column 2 is installed so as to protrude into the first housing 7, and is fixed to the first housing 7 via a vacuum sealing member 123. A detector 3 for detecting secondary charged particles (secondary electrons or reflected electrons) obtained by irradiation with the primary charged particle beam is disposed at the end of the charged particle optical column 2. In the configuration example shown in FIG. 1, the detector 3 is provided in the first housing 7, but may be disposed in the charged particle optical column 2 or in the second housing 121.

  The charged particle microscope of the present embodiment has a control system such as a personal computer 35 used by a user of the apparatus, a host controller 36 connected to the personal computer 35 for communication, and a vacuum exhaust system and a charge according to a command transmitted from the host controller 36. A lower control unit 37 that controls the particle optical system and the like is provided. The personal computer 35 includes a monitor on which an operation screen (GUI) of the apparatus is displayed, and input means for an operation screen such as a keyboard and a mouse. The upper control unit 36, the lower control unit 37, and the personal computer 35 are connected by communication lines 43 and 44, respectively.

  The lower control unit 37 is a part that transmits and receives control signals for controlling the vacuum pump 4, the gas control valve 101, the charged particle source 0, the optical lens 1, and the like, and further outputs the output signal of the detector 3 as a digital image signal. And is transmitted to the upper control unit 36. Although the output signal from the detector 3 is connected to the lower control unit 37 in the figure, an amplifier such as a preamplifier may be interposed.

  The upper control unit 36 and the lower control unit 37 may include a mixture of analog circuits, digital circuits, etc., and the upper control unit 36 and the lower control unit 37 may be unified. Note that the configuration of the control system shown in FIG. 1 is merely an example, and modifications of the control unit, valves, vacuum pumps, communication wiring, and the like can be applied to the SEM of this embodiment as long as the functions intended in this embodiment are satisfied. It belongs to the category of charged particle beam equipment.

  A vacuum pipe 16 having one end connected to the vacuum pump 4 is connected to the first housing 7 so that the inside can be maintained in a vacuum state. At the same time, a leak valve 14 for releasing the inside of the housing to the atmosphere is provided, and the inside of the first housing 7 can be opened to the atmosphere during maintenance. The leak valve 14 may not be provided, and may be two or more. Moreover, the arrangement location in the 1st housing | casing 7 is not restricted to the location shown by FIG. 1, You may arrange | position in the other position on the 1st housing | casing 7. FIG. Furthermore, the first housing 7 has an opening on the side surface, and the second housing 121 is inserted through the opening.

  The second casing 121 includes a rectangular parallelepiped body portion 131 and a mating portion 132. The main body 131 has a function of storing the sample 6 to be observed, and is inserted into the first housing 7 through the opening. The mating portion 132 forms a mating surface with the outer wall surface on the side surface side where the opening of the first housing 7 is provided, and is fixed to the outer wall surface on the side surface side via the vacuum sealing member 126. As a result, the entire second housing 121 is fitted into the first housing 7. The opening is most easily manufactured using the opening for loading and unloading the sample originally provided in the vacuum sample chamber of the charged particle microscope. That is, if the second casing 121 is manufactured according to the size of the hole that is originally open and the vacuum sealing member 126 is attached around the hole, the modification of the apparatus is minimized.

  On the upper surface side of the main body 131, the thin film 10 is provided at a position immediately below the charged particle optical column 2 when the entire second housing 121 is fitted into the first housing 7. The thin film 10 can transmit or pass the primary charged particle beam emitted from the lower end of the charged particle optical column 2, and the primary charged particle beam finally reaches the sample 6 through the thin film 10. To do.

When the charged particle beam is an electron beam, the thickness of the thin film 10 needs to be a thickness that can transmit the electron beam, typically about 20 μm or less. In place of the thin film, an aperture member having a primary charged particle beam passage hole may be used. In this case, the hole diameter should be about 1 mm ² or less because of the requirement that a differential vacuum pumping is possible with a realistic vacuum pump. Is desirable. When the charged particle beam is an ion, it is difficult to penetrate without damaging the thin film, so an aperture having an area of about 1 mm ² or less is used. A one-dot chain line in the figure indicates the optical axis of the primary charged particle beam, and the charged particle optical column 2, the first casing 7 and the thin film 10 are arranged coaxially with the primary charged particle beam optical axis. . The distance between the sample 6 and the thin film 10 is adjusted by placing a sample table 17 having an appropriate height.

  As shown in FIG. 1, the side surface of the second housing 121 is an open surface, and the sample 6 stored inside the second housing 121 (right side of the dotted line in the figure; hereinafter referred to as a second space) During observation, it is placed at atmospheric pressure. On the other hand, a vacuum pump 4 is connected to the first housing 7, and a closed space (hereinafter referred to as a first space) constituted by the inner wall surface of the first housing 7, the outer wall surface of the second housing and the thin film 10. Can be evacuated. Therefore, in this embodiment, the charged particle optical column 2 and the detector 3 can be maintained in a vacuum state and the sample 6 can be maintained at atmospheric pressure during the operation of the apparatus. Further, since the second casing 121 has an open surface, the sample 6 can be freely exchanged during observation.

  As described above, according to the present embodiment, a charged particle microscope capable of observing even a relatively large sample size at atmospheric pressure is realized.

  In this embodiment, an application example to a desktop scanning electron microscope will be described. In addition, although it is an application example to a scanning electron microscope, it cannot be overemphasized that a present Example is applicable to general charged particle microscopes, such as an ion microscope.

  FIG. 2 shows an overall configuration diagram of the scanning electron microscope of the present embodiment. Similar to the first embodiment, the scanning electron microscope of the present embodiment also includes the electron optical column 2, the first casing (vacuum chamber) 7 that supports the electron optical column with respect to the apparatus installation surface, and the first casing 7. It is comprised by the 2nd housing | casing (attachment) 121 control system etc. which are inserted and used for. Since the operations and functions of these elements or additional elements added to the elements are substantially the same as those in the first embodiment, detailed description thereof is omitted.

  In the scanning electron microscope of this embodiment, unlike the first embodiment, the thin film 10 is detachably fixed to the upper surface of the main body 131 of the second housing via the thin film holding member 47. . The thin film 10 is fixed to the thin film holding member 47 so as to be vacuum-sealed, but a vacuum sealing member such as an O-ring may be used, or may be fixed with an organic material such as an adhesive or a tape. May be.

The thin film holding member 47 is detachably fixed to the lower surface side of the ceiling plate of the second housing 121 via a vacuum sealing member. The thin film 10 is very thin with a thickness of about 20 μm or less because of the requirement for transmission of the electron beam, and therefore there is a possibility that it deteriorates with time or breaks during observation preparation. On the other hand, since the thin film 10 is thin, it is very difficult to handle it directly. Since the thin film 10 can be handled through the thin film holding member 47 instead of directly as in the present embodiment, handling (particularly replacement) of the thin film 10 becomes very easy. That is, when the thin film 10 is damaged, the thin film holding member 47 may be replaced. Even if the thin film 10 must be replaced directly, the thin film holding member 47 is taken out of the apparatus and the thin film 10 is replaced. Can be done externally. The aperture member having a hole with an area of about 1 mm ² or less can be used in place of the thin film, as in the first embodiment.

  Furthermore, the thin film holding member 47 of this embodiment includes a limiting member 105 that prevents the thin film and the sample from contacting each other on the side facing the sample 6. Any member can be used as the restricting member 105 as long as it can restrict the distance between the sample and the thin film, but for convenience, an adhesive or a tape can be attached to the restricting member 105. However, considering the mean free path of the primary electron beam that has passed through the thin film 10, the limiting member 105 is preferably made of a thin film material whose thickness is accurately known. In FIG. 2, the limiting member 105 is attached to the thin film holding member 47, but it may be attached to the thin film 10 itself, the sample stage 5, or placed on the sample 6. Furthermore, the limiting member 105 may be detachable.

  In the case of the scanning electron microscope of the present embodiment, the open surface of the second housing 121 can be covered with the lid member 122, and various functions can be realized. This will be described below.

  The scanning electron microscope of this embodiment has a function of supplying a replacement gas into the second housing. The electron beam emitted from the lower end of the electron optical column 2 passes through the first space maintained at a high vacuum, passes through the thin film 10 (or aperture member) shown in FIG. It penetrates into the second space maintained at a low vacuum (rather than the first space). However, since the electron beam is scattered by gas molecules in a low vacuum space, the mean free path is shortened. That is, when the distance between the thin film 10 and the sample 6 is large, secondary electrons or reflected electrons generated by electron beam or electron beam irradiation do not reach the sample. On the other hand, the scattering probability of electron beams is proportional to the mass number of gas molecules. Therefore, if the second space is replaced with gas molecules having a lighter mass number than the atmosphere, the scattering probability of the electron beam decreases and the electron beam can reach the sample. As the type of the replacement gas, if the gas is lighter than the atmosphere, such as nitrogen or water vapor, the effect of improving the image S / N can be seen, but helium gas or hydrogen gas having a lighter mass has a better image S / N. Great improvement effect.

  For the above reasons, in the scanning electron microscope of the present embodiment, the lid member 122 is provided with an attachment portion (gas introduction portion) for the gas supply pipe 100. The gas supply pipe 100 is connected to the gas cylinder 103 by the connecting portion 102, whereby the replacement gas is introduced into the second space 12. A gas control valve 101 is arranged in the middle of the gas supply pipe 100, and the flow rate of the replacement gas flowing through the pipe can be controlled. For this reason, a signal line extends from the gas control valve 101 to the lower control unit 37, and the apparatus user can control the flow rate of the replacement gas on the operation screen displayed on the monitor of the personal computer 35.

  Since the replacement gas is a light element gas, it tends to accumulate in the upper part of the second space 12, and the lower side is difficult to replace. Therefore, an opening is provided in the lid member 122 below the attachment position of the gas supply pipe 100 (the attachment position of the pressure regulating valve 104 in FIG. 2). Thereby, since it pushes by the light element gas introduced from the gas introduction part and atmospheric gas is discharged | emitted from lower opening, the inside of the 2nd housing | casing 121 can be substituted efficiently. Note that this opening may also be used as a rough exhaust port described later.

  The second casing 121 or the lid member 122 may be provided with a vacuum exhaust port, and the replacement gas may be introduced after the second casing 121 is evacuated once. The vacuum evacuation in this case does not require high vacuum evacuation because the atmospheric gas component remaining in the second housing 121 may be reduced to a certain amount or less, and rough evacuation is sufficient. However, when observing a sample containing moisture such as a biological sample, the sample once placed in a vacuum state changes its state due to evaporation of moisture. Therefore, as described above, it is preferable to introduce the replacement gas directly from the air atmosphere. The opening can be closed in the second space 12 by closing the opening with a lid member after the introduction of the replacement gas.

  If a three-way valve is attached to the position of the opening, this opening can be used also as a rough exhaust port and an air leak exhaust port. That is, if one of the three-way valves is attached to the lid member 122, one is connected to the rough exhaust vacuum pump, and the leak valve is attached to the other one, the above-described dual exhaust port can be realized.

  A pressure regulating valve 104 may be provided instead of the opening described above. The pressure regulating valve 104 has a function of automatically opening the valve when the internal pressure of the second housing 121 becomes 1 atm or more. By providing a pressure regulating valve with such a function, when light element gas is introduced, it automatically opens when the internal pressure reaches 1 atm or more and discharges atmospheric gas components such as nitrogen and oxygen to the outside of the device. The element gas can be filled in the apparatus. Note that the illustrated gas cylinder 103 may be provided in a scanning electron microscope or may be attached later by an apparatus user.

  Next, a method for adjusting the position of the sample 6 will be described. The scanning electron microscope of the present embodiment includes a sample stage 5 as means for moving the observation field. The sample stage 5 includes an XY drive mechanism in the in-plane direction and a Z-axis drive mechanism in the height direction. A support plate 107 serving as a bottom plate for supporting the sample stage 5 is attached to the lid member 122, and the sample stage 5 is fixed to the support plate 107. The support plate 107 is attached to the surface of the lid member 122 facing the second housing 121 so as to extend toward the inside of the second housing 121. Support shafts extend from the Z-axis drive mechanism and the XY drive mechanism, respectively, and are connected to the operation knob 108 and the operation knob 109, respectively. The apparatus user adjusts the position of the sample 6 in the second housing 121 by operating these operation knobs 108 and 109.

  When adjusting the position of the sample, the position in the height direction is usually adjusted after determining the position in the in-plane direction. However, in order to prevent the thin film 10 from being damaged, the position of the sample 6 in the height direction is adjusted. It is necessary to adjust so that it does not get too close. Therefore, the scanning electron microscope of this embodiment includes observation means such as a camera 106. This makes it possible to remotely observe the distance between the thin film 10 and the sample 6 and how the sample 6 is moved in the height direction. Instead of the camera 106, an optical microscope with high imaging resolution may be used. Although not shown, the distance between the sample and the thin film may be measured using reflection of electromagnetic waves such as infrared rays. The attachment position of the observation means is not particularly limited to the arrangement shown in FIG. 2 and may be any position as long as the distance between the sample and the thin film can be clearly measured.

  Next, the exchange mechanism of the sample 6 will be described. The scanning electron microscope of the present embodiment includes a plate member support member 19 and a bottom plate 20 on the bottom surface of the first housing 7 and the lower end portion of the lid member 122, respectively. The lid member 122 is detachably fixed to the second housing 121 via a vacuum sealing member 125. On the other hand, the plate member support member 19 is also detachably fixed to the bottom plate 20, and the lid member 122 and the plate member support member 19 can be completely removed from the second housing 121 as shown in FIG. 3. Is possible.

  The bottom plate 20 includes a column 18 that is used as a guide during removal. In a normal state, the support column 18 is stored in a storage unit provided on the bottom plate 20, and is configured to extend in the pull-out direction of the lid member 122 when being removed. At the same time, the column 18 is fixed to the plate member support member 19, and the lid member 122 and the scanning electron microscope main body are not completely separated when the lid member 122 is removed from the second housing 121. ing. Thereby, the sample stage 5 or the sample 6 can be prevented from dropping.

  When the sample is carried into the second housing 121, first, the sample 6 is moved away from the thin film 10 by turning the Z-axis operation knob of the sample stage 5. Next, the pressure regulating valve 104 is opened, and the inside of the second housing is opened to the atmosphere. Thereafter, after confirming that the inside of the second housing is not in a reduced pressure state or an extremely pressurized state, the lid member 122 is pulled out to the side opposite to the apparatus main body. As a result, the sample 6 can be exchanged. After the sample replacement, the lid member 122 is pushed into the second housing 121, and the lid member 122 is fixed to the mating portion 132 with a fastening member (not shown), and then a replacement gas is introduced. The above operation can be executed while the operation of the electron optical column 2 is continued. Therefore, the scanning electron microscope of this embodiment can start observation quickly after exchanging the sample.

  The scanning electron microscope of this embodiment can also be used as a normal high vacuum SEM. FIG. 4 shows an overall configuration diagram of the scanning electron microscope of the present example in a state where it is used as a high vacuum SEM. In FIG. 4, the control system is the same as in FIG. FIG. 4 shows a state where the gas supply pipe 100 and the pressure adjustment valve 104 are attached after the gas supply pipe 100 and the pressure adjustment valve 104 are removed from the lid member 122 in a state where the lid member 122 is fixed to the second housing 121. A scanning electron microscope in a state of being covered with a lid member 130 is shown. If the thin film holding member 47 is removed from the second housing 121 by the operation before and after this operation, the first space 11 and the second space 12 can be connected, and the inside of the second housing is vacuumed by the vacuum pump 4. It becomes possible to exhaust. As a result, high vacuum SEM observation is possible with the second housing 121 attached.

  As a modification of the configuration of FIG. 4, the entire second housing 121 with the thin film holding member 47 attached may be removed and the lid member 122 may be directly fixed to the mating surface of the first housing 7. Also with this configuration, the first space 11 and the second space 12 can be connected, and the inside of the second housing can be evacuated by the vacuum pump 4. This configuration is the same as that of a general SEM apparatus.

  As described above, in this embodiment, the sample stage 5 and its operation knobs 108 and 109, the gas supply pipe 100, and the pressure adjustment valve 104 are all attached to the lid member 122. Therefore, the apparatus user can perform the operation of the operation knobs 108 and 109, the sample replacement work, or the detachment work of the gas supply pipe 100 and the pressure regulating valve 104 on the same surface of the first housing. Therefore, the operability is greatly improved as compared with a scanning electron microscope having a configuration in which the above-described components are separately attached to the other surfaces of the sample chamber.

  FIG. 5 shows a flowchart showing the operation flow of the scanning electron microscope of the present embodiment.

In the first step 70, the first space is evacuated. It may be evacuated in advance. In the second step 71, the sample 6 is placed on the sample stage on the sample stage 5 and mounted on the sample stage 5. In the third step 72, the lid member 122 is introduced into the second housing and fastened to the apparatus main body (second housing). In the fourth step 73, the gas control valve 101 is opened for a certain time and then closed to introduce a replacement gas such as helium gas into the second space. In the fifth step 74, the operating condition of the electron optical column is adjusted to emit an electron beam. In the sixth step 75, image acquisition is started. In the seventh step 76, the lid member 122 is removed. Although the replacement gas confined in the second space is released to the outside of the apparatus, the lid member 122 may be removed after the pressure adjustment valve is opened and the replacement gas is discharged. In an eighth step 77, the sample is removed. When it is desired to observe another sample, the process returns to the second step 71.

  Note that the second space can be not only introduced with the replacement gas up to the atmospheric pressure state but also in a low vacuum state or a vacuum state in which the replacement gas is introduced a little. In this case, the fourth step 73 is performed. Then, the flow rate of the replacement gas or vacuum evacuation may be performed. The flow shown in FIG. 5 is an example of the operation, and the order may be changed as appropriate.

  FIG. 6 shows an example of an operation screen displayed on the monitor of the personal computer 35. In the operation screen shown in FIG. 6, for example, the operation window 50, the image display unit 51, the image observation start button 52 for starting the emission of the electron beam and starting the image display, and the emission of the electron beam are stopped and the image is displayed. An image observation stop button 53 for stopping display, a focus adjustment button 54 for adjusting an optical lens such as a deflection lens and an objective lens, and executing a focus, a brightness adjustment button 55 for adjusting the brightness of an image, and a contrast. Contrast adjustment button 56 to be adjusted, evacuation button 57 for starting evacuation inside charged particle optical column 2 and first casing 7 and atmospheric leak for causing the inside of first casing 7 to leak to the atmosphere There is a button 58. When the evacuation button 57 is clicked on the screen, evacuation is started, and when it is clicked again, evacuation is stopped. The operation of the air leak button 58 is the same. The processing executed by the above button operation can also be executed manually by operating a mechanical button or knob on the apparatus main body.

  In the operation window 50, a gas release start button 112 for opening the gas control valve 101 to release gas from the gas nozzle, a gas release stop button 113 for closing the gas control valve 101 and stopping gas release, a scanning electron microscope The SEM image display button 114 for displaying the image captured in step S1 on the image display unit 51 and the camera button 115 for displaying the acquired image of the camera 106 are displayed. If the simultaneous display button 116 is clicked, both the SEM image and the camera image can be displayed on the image display unit 51, which is particularly effective when adjusting the height of the sample 6.

  In the case of the present embodiment, if the gas discharge start button 112 is pressed to open the gas control valve 101 and then the gas discharge stop button 113 is forgotten to be pressed, the gas in the gas cylinder 103 may be exhausted. Therefore, as shown in FIG. 7, a gas discharge time setting screen 117 for setting a gas discharge duration from when gas discharge is started to when it is stopped may be displayed on the child window 118. Further, the time from when the gas is released to when the gas is stopped is not set by the user of the apparatus, but a time preset in the apparatus may be used.

  In some cases, it is desired to release gas only when observing an SEM image. In that case, the other window 118 shown in FIG. 7 is displayed, and a check mark is put in the check box 119 in advance. When the image observation start button 52 is clicked with the check mark on, the gas control valve 101 is automatically opened and the introduction of the replacement gas is started. Thereafter, when the time set on the gas discharge time setting screen 117 has elapsed, the gas control valve 101 is automatically closed. Even when the image observation stop button 53 is clicked during the introduction of the replacement gas, the gas control valve 101 is also automatically closed. Note that when the SEM image display button 114, the camera button 115, or the simultaneous display button 116 is clicked during the introduction of the replacement gas, the image displayed on the image display unit 51 can be switched according to the type of the selected image. . The opening / closing control of the gas control valve 101 described above is executed by the lower control unit 37 based on the setting information in the personal computer 35 transmitted from the upper control unit.

  FIG. 8 shows an example of an operation screen when a rough exhaust port or a three-way valve is provided in the lid member 122 or the second housing 121. On the operation screen in this case, the evacuation start / stop buttons for the first space and the second space are displayed separately. When the vacuum exhaust button 59 for the second space is clicked, the vacuum valve provided in the rough exhaust port is opened, and the vacuum exhaust of the second space is started. If clicked again, the vacuum valve of the rough exhaust port closes and the vacuum exhaust stops. Similarly, when the atmospheric leak button 60 for the second space is clicked, the leak valve attached to the three-way valve is opened and the second space is opened to the atmosphere. If clicked again, the leak valve closes and the release of the space 2 into the atmosphere stops.

  In addition to the configuration described above, a contact monitor that detects the contact state between the second housing 121 and the lid member 122 may be provided to monitor whether the second space is closed or open.

  Further, in addition to the secondary electron detector and the backscattered electron detector, an X-ray detector and a photodetector may be provided so that EDS analysis and fluorescent ray detection can be performed. The arrangement of the X-ray detector and the photodetector may be either the first space 11 or the second space 12.

  Further, when the sample 6 is irradiated with the electron beam, an absorption current flows through the sample. Therefore, an ammeter may be provided so that the current flowing through the sample 6 or the sample stage can be measured. Thereby, an absorption current image (or an image using absorption electrons) can be acquired. Further, a transmission electron detector may be disposed below the sample stage so that a scanning transmission (STEM) image can be acquired. The sample stage itself may be a detector.

  Further, a high voltage may be applied to the sample stage 5. When a high voltage is applied to the sample 6, the electrons emitted from the sample 6 can have high energy, the signal amount can be increased, and the image S / N is improved.

  In addition, the configuration of this embodiment can be applied to a small electron beam drawing apparatus. In this case, the detector 3 is not always necessary.

  As described above, according to this embodiment, an atmospheric pressure SEM that can be used as a high vacuum SEM is realized in addition to the effects of the first embodiment. In addition, since the observation can be performed by introducing a replacement gas, the scanning electron microscope of the present embodiment can acquire an image having a better S / N than the charged particle microscope of the first embodiment.

  In addition, although the present Example demonstrated the structural example which intended the desktop electron microscope, this Example can also be applied to a large sized scanning electron microscope. In the case of a desktop electron microscope, the entire apparatus or charged particle optical column is supported on the apparatus installation surface by a housing. However, in the case of a large scanning electron microscope, the entire apparatus may be placed on a pedestal. If the first casing 7 is placed on a gantry, the configuration described in this embodiment can be used as it is for a large scanning electron microscope.

  In this embodiment, a configuration example in which the lid member 122 is removed from the device configuration in FIG. 2 will be described. In FIG. 9, the whole structure of the charged particle microscope of a present Example is shown. Since the control system is the same as that of the second embodiment, the illustration is omitted, and only the main part of the apparatus is shown.

  In the configuration shown in FIG. 9, the sample stage 5 is directly fixed to the bottom surface of the second housing 121. The gas supply pipe 100 may or may not be fixed to the second casing 121. According to this configuration, since the sample is allowed to protrude outside the apparatus, it is possible to observe a sample having a size larger than that of the configuration of the second embodiment including the lid member 122.

  In the present embodiment, a modification in which the positional relationship between the second casing 121 and the lid member 122 is changed in the apparatus configuration of FIG. 2 will be described. In FIG. 10, the whole structure of the charged particle microscope of a present Example is shown. As in the third embodiment, only the main part of the apparatus is shown in FIG. In this configuration, a vacuum sealing member 128 for vacuum-sealing the first space 11 and the second space 12 is necessary. In the case of this configuration, since the mating portion 132 of the second housing is inside the device, the size of the entire device can be made smaller than the configurations of the first to third embodiments.

  In the present embodiment, a modification in which the second housing 121 is vacuum-sealed on the upper side of the first housing in the apparatus configuration of FIG. 2 will be described. FIG. 11 shows the overall configuration of the charged particle microscope of this example. As in the fourth embodiment, only the main part of the apparatus is shown in FIG. In this configuration, a pan-type attachment (second housing 121) is used to fit the attachment into the first housing 7 from above, and the electro-optic lens barrel 2 from above. The second casing 121 is vacuum-sealed with respect to the electron optical column 2 by a vacuum sealing member 123, and the second casing 121 is vacuum-sealed with respect to the first casing 7 with a vacuum sealing member 129. . In the case of this configuration, the volume of the second space 11 can be increased as compared with FIG. 2, and a larger sample can be arranged than the configuration of the second embodiment.

0 electron source (charged particle source)
DESCRIPTION OF SYMBOLS 1 Optical lens 2 Electron optics (charged particle optics) lens barrel 3 Detector 4 Vacuum pump 5 Sample stage 6 Sample 7 1st housing | casing 10 Thin film 11 1st space 12 2nd space 14 Leak valve 16 Vacuum piping 18 Support | pillar 19 plate member support member 20 bottom plate 35 personal computer 36 upper control unit 37 lower control units 43 and 44 communication line 47 thin film holding member 50 operation window 51 image display unit 52 image observation start button 53 image observation stop button 54 focus adjustment button 55 Brightness adjustment button 56 Contrast adjustment button 57, 59 Vacuum exhaust button 58, 60 Atmospheric leak button 100 Gas supply pipe 101 Gas control valve 102 Connecting portion 103 Gas cylinder 104 Pressure adjustment valve 105 Restriction member 106 Camera 107 Support plate 108, 109 Operation Knob 112 Gas release start button 113 Gas release Stop button 114 SEM image display button 115 Camera button 116 Simultaneous display button 117 Gas release time setting screen 118 Child window 119 Gas release execution check box 120 OK button 121 Second casing 122, 130 Lid members 123, 124, 125, 126, 128, 129 Vacuum sealing member 131 Body portion 132 Matching portion

In the present invention, an attachment capable of storing the sample is inserted into the vacuum chamber provided in the charged particle microscope from the opening of the vacuum chamber while maintaining an internal pressure higher than the pressure in the vacuum chamber. However, the above-mentioned problem is solved by fixing the vacuum chamber to use. The opening part of a vacuum chamber is provided in the side surface or bottom face of the said vacuum chamber, for example. Further, the above attachment has a function of holding a thin film that allows the primary charged particle beam to pass through or pass through the inside of the attachment, thereby ensuring a pressure difference between the vacuum chamber and the inside of the attachment. The vacuum chamber may be called a first casing, and the attachment may be called a second casing for the vacuum chamber. In the charged particle beam apparatus comprising: a charged particle optical column that scans a sample with a primary charged particle beam; a detector that detects reflected electrons or secondary electrons obtained by the scanning; and a vacuum pump. A first casing that forms a first space maintained in a vacuum state by a pump; a second casing that forms a second space in which a sample is placed; and a thin film through which the primary charged particle beam passes A thin film holding member that is detachably fixed so as to partition the first space and the second space, and the thin film holding member is fixed to the charged particle beam device The first space and the second space are partitioned by the thin film so that the second space can be maintained at a higher pressure than the first space, and the thin film holding member is Field removed from charged particle beam equipment The communicates said first space and the second space, a configuration is possible to evacuate the second space.

Claims (17)

In a charged particle beam apparatus comprising a charged particle optical column that scans a sample with a primary charged particle beam, a detector that detects reflected electrons or secondary electrons obtained by the scanning, and a vacuum pump,
A first housing forming a first space maintained in a vacuum state by the vacuum pump;
A second housing forming a second space in which the sample is placed;
A thin film holding member that holds the thin film through which the primary charged particle beam is transmitted and is detachably fixed so as to partition the first space and the second space;
When the thin film holding member is fixed to the charged particle beam device, the first space and the second space are partitioned by the thin film, so that the second space is separated from the first space. The pressure can be kept high,
When the thin film holding member is removed from the charged particle beam device, the charged particle beam device can communicate the first space with the second space and evacuate the second space. . The charged particle beam apparatus according to claim 1,
The first casing is a charged particle beam apparatus that supports the entire charged particle beam apparatus with respect to the apparatus installation surface, and the inside is evacuated by the vacuum pump. The charged particle beam apparatus according to claim 1,
The thin film holding member is a charged particle beam device provided on an upper surface side of the second casing. The charged particle beam apparatus according to claim 1,
A charged particle beam apparatus comprising: a lid member that covers the one opened side surface, wherein the second casing has a rectangular parallelepiped shape with one side surface opened. The charged particle beam device according to claim 4,
The charged particle beam apparatus, wherein the lid member is detachably fixed to a side surface of the second casing. The charged particle beam apparatus according to claim 1,
The second housing includes a main body portion inserted into the first housing and a mating portion whose position is fixed to the outer wall surface of the first housing via a vacuum sealing member. Charged particle beam equipment. The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus according to claim 1, wherein the first casing is attached to an outer wall of an upper surface of the second casing. The charged particle beam device according to claim 7,
A charged particle beam apparatus further comprising a lid member that is detachably fixed to a side surface of the second casing. The charged particle beam apparatus according to claim 1,
The second casing has an open surface on which the sample stored in the second casing can be exchanged while maintaining a vacuum state in the first casing. Particle beam device. The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the thin film holding unit includes a limiting member that limits a distance between the sample and the thin film. The charged particle beam apparatus according to claim 1,
A charged particle beam apparatus comprising an observation device capable of observing or measuring a distance between the thin film and the sample. A sample observation method using a charged particle beam apparatus comprising: a charged particle optical column that scans a sample with a primary charged particle beam; a detector that detects reflected electrons or secondary electrons obtained by the scanning; and a vacuum pump. In
The charged particle beam apparatus partitions a thin film holding member holding a thin film through which the primary charged particle beam is transmitted into a first space where the vacuum pump is maintained and a second space where a sample is placed. The first space and the second space are partitioned by the thin film in a state of being fixed to the first space, so that the second space is maintained at a higher pressure than the first space, and an image of the sample is obtained. Step to get the
With the thin film holding member removed from the charged particle beam device, the first space and the second space are communicated, and the second space is evacuated to obtain an image of the sample. And a sample observation method. The sample observation method according to claim 12,
A sample observation method of covering one side surface of the second space with a lid member. The sample observation method according to claim 13,
The sample observing method, wherein the lid member is detachably fixed to a side surface of a second housing forming the second space. The sample observation method according to claim 12,
A sample observation method of exchanging the sample arranged in the second space while maintaining the vacuum state of the first space. The sample observation method according to claim 12,
A sample observation method for limiting a distance between the sample and the thin film. The sample observation method according to claim 12,
A sample observation method for observing or measuring an interval between the thin film and the sample.

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