JP6016938B2 - Charged particle beam apparatus and observation method using the same - Google Patents

Description

  The present invention relates to a charged particle beam apparatus and an observation method using the same.

  In a charged particle beam apparatus typified by a scanning electron microscope, desired information (for example, a sample image) is obtained from a sample by scanning a finely focused charged particle beam on the sample. A STEM image is an image obtained by detecting electrons transmitted through interaction with a sample.

  The transmitted electrons that have passed through the sample are divided into a bright-field STEM signal and a dark-field STEM signal depending on the scattering angle (detection angle). The bright field STEM signal has information on the thickness, density, and crystal structure of the sample, whereas the dark field STEM signal reflects the difference in the scattering angle (detection angle) depending on the atomic number (Z) in the contrast. Is done. A heavy element has a large scattering angle (detection angle) and a light element has a small scattering angle, resulting in a difference in contrast (Z contrast image).

  Patent Document 1 discloses a technique in which dark field STEM signal electrons are converted into secondary electrons by a reflector (dark field STEM signal conversion electrode) arranged on a sample holder and detected by a lower detector. Further, Patent Document 2 discloses a method of controlling a capture angle of transmitted and scattered electrons by installing a dark field STEM detector immediately below a sample as a technique used in an in-lens SEM.

JP 2004-253369 A JP 2006-190567 A

  The configuration of Patent Document 1 is widely used because dark field STEM observation can be easily performed without preparing a dedicated STEM detector. However, the following problems can be considered for the reason of the configuration. Reflected electrons and bright field STEM signal electrons generated from the sample collide with members and holders in the sample chamber, and secondary electrons (components that cause noise) are generated therefrom and detected by the lower detector. Thus, in patent document 1, there exists a subject of mixing of noise.

  The SEM of Patent Document 2 is an in-lens SEM, and is a type of SEM that does not have a large stage mechanism directly below the sample holder. Therefore, the technique of Patent Document 2 cannot be applied to a charged particle beam apparatus in which a sample holder is disposed on a stage mechanism, such as a semi-in lens SEM or an out lens SEM.

  The present invention has been made under the recognition of such a new problem by the inventor of the present application, and an object thereof is to reduce the mixing of noise when detecting dark field STEM signal electrons.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-described problem. To give an example, in a charged particle beam apparatus including a stage mechanism and a sample holder disposed on the stage mechanism, the sample holder includes: A dark field STEM detector for detecting dark field STEM signal particles transmitted through the sample mounted on the sample holder;

  According to the present invention, since the dark field STEM signal particles are directly detected by the dark field STEM detector provided in the sample holder, there is little mixing of noise, and the S / N of the obtained dark field STEM image is high.

  Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. Further, problems, configurations and effects other than those described above will be clarified by the description of the following examples.

It is a schematic block diagram of the charged particle beam apparatus to which this invention is applied. It is a schematic block diagram of the sample stage mechanism and sample holder of the charged particle beam apparatus which concerns on 1st Example. It is the figure which showed typically the relationship between the signal intensity of the transmission electron with respect to a different material, and a scattering angle. It is the chart which showed the process of sample observation using the charged particle beam device concerning the 1st example. It is a schematic block diagram of the sample holder of the charged particle beam apparatus which concerns on 3rd Example. It is a schematic block diagram of the sample holder of the charged particle beam apparatus which concerns on 4th Example. It is a schematic block diagram of the sample holder of the charged particle beam apparatus which concerns on 5th Example. It is a schematic block diagram of the sample holder of the charged particle beam apparatus which concerns on 6th Example. It is a top view of the sample holder of the charged particle beam apparatus which concerns on 8th Example. It is sectional drawing of the sample holder of the charged particle beam apparatus which concerns on 8th Example. It is the chart which showed the process of sample observation using the charged particle beam device concerning the 8th example. It is a schematic block diagram of the sample holder of the charged particle beam apparatus which concerns on 9th Example.

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

<First embodiment>
Hereinafter, a charged particle beam device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a charged particle beam apparatus to which the present invention is applied.

  As shown in FIG. 1, the technique described below is directed to a charged particle beam apparatus 10 in which a sample holder is arranged on a stage mechanism, such as a semi-in lens SEM or an out lens SEM. The charged particle beam device 10 includes a cathode 1, a first anode 2 and a second anode 4, a first focusing lens 5, an objective lens aperture 6, two-stage deflection coils 7 and 8, a secondary A signal particle detector 9, a sample stage mechanism 16, a transmission signal detector 17, a diaphragm 19, an objective lens 20, and an orthogonal electromagnetic field generator 22 are provided. A sample holder 21 is disposed on the sample stage mechanism 16, and a sample (for example, a thin film sample) 14 is mounted on the sample holder 21.

  In the charged particle beam device 10, the primary charged particle beam 3 emitted from the cathode 1 by a voltage (not shown) applied to the cathode 1 and the first anode 2 is applied to the voltage Vacc applied to the second anode 4. It is accelerated (not shown) and proceeds to the subsequent lens system. The primary charged particle beam 3 is once converged by the first focusing lens 5 and the irradiation angle of the beam is limited by the objective lens aperture 6. Thereafter, the primary charged particle beam 3 is scanned two-dimensionally on the sample 14 by the two-stage deflection coils 7 and 8. The secondary signal particles 11 generated from the irradiation point of the primary charged particle beam 3 on the surface of the sample 14 are wound up by the magnetic field generated by the objective lens 20 and travel above the objective lens 20 (on the electron source side). The secondary signal particles 11 are orbitally separated from the primary charged particle beam 3 by the orthogonal electromagnetic field generator 22 and detected by the secondary signal particle detector 9.

  In the present embodiment, the sample holder 21 includes a dark field STEM semiconductor element (dark field STEM detector) 15. Details of the sample stage mechanism 16 and the dark field STEM semiconductor element 15 will be described later. Of the transmitted signal particles transmitted through the sample 14 mounted on the sample holder 21, dark field STEM signal particles (18 b in FIG. 2) scattered within the sample 14 are dark field STEM semiconductor elements 15 provided below the sample 14. , Detected as a dark field transmission signal. As described above, by directly detecting the dark field STEM signal particles by the dark field STEM semiconductor element 15 provided in the sample holder 21, the mixing of noise can be reduced.

  On the other hand, among the transmitted signal particles, only the bright field STEM signal particles that have passed through the passage hole 16 a of the stage are detected by the transmitted signal detector 17. Further, a diaphragm 19 is provided between the sample stage mechanism 16 and the transmission signal detector 17 to limit the scattering angle (detection angle) of transmission signal particles detected by the transmission signal detector 17.

  Further, in order to obtain a high-contrast dark field image, it is important to control the detection angle according to the sample 14. However, for example, in a scanning electron microscope capable of observing a large sample, a converging lens cannot be disposed below the sample as in a transmission electron microscope. For this reason, there is a problem that the detection angle of the dark field signal cannot be controlled (optimized). Therefore, a configuration that enables control of the detection angle of the dark field signal will be described below. FIG. 2 is a schematic configuration diagram of the sample stage mechanism and the sample holder according to the first embodiment, and is a cross-sectional view of the sample stage mechanism and the sample holder.

  The sample stage mechanism 16 (see FIG. 1) includes a first stage 211 and a second stage 212. The sample holder 21 includes a sample holder main body 201, a dark field STEM semiconductor element (dark field STEM detector) 204, and a semiconductor element vertical movement mechanism 205.

  The sample holder main body 201 is a base for fixing the sample 14 to the first stage 211 in the sample chamber of the charged particle beam apparatus 10 after mounting the sample 14. The sample holder main body 201 includes a column member 201a extending in the vertical direction, an upper member 201b extending from the upper end of the column member 201a to a position above the dark field STEM semiconductor element 204, and the first stage 211 from the lower end of the column member 201a. And a lower member 201c disposed on the first stage 211. The upper member 201b of the sample holder body 201 has a sample mounting position 202, and a mechanism for mounting or fixing a mesh or the like on which the sample 14 is placed is provided at the sample mounting position 202. Examples of this mechanism include a mechanism for screwing the pressing plate. The sample holder 21 can be attached to and detached from the first stage 211.

  When the sample 14 is a thin film, when the sample 14 is irradiated with the primary charged particle beam 203, dark field STEM signal particles transmitted through the sample 14 mounted on the sample holder 21 are detected by the dark field STEM semiconductor element 204. The dark field STEM semiconductor element 204 is an annular type semiconductor detector using a PN junction type semiconductor element, and a plurality of channels used as a conventional backscattered electron detector or an STEM detector used in Patent Document 2. This means a semiconductor element.

  In this embodiment, the dark field STEM semiconductor element 204 is attached to the semiconductor element vertical movement mechanism 205. The semiconductor element vertical movement mechanism 205 includes a column 205a and a fixture 206 (for example, a screw). The dark field STEM semiconductor element 204 is fixed to the column 205a by a fixing tool 206. The support column 205a of the semiconductor element vertical movement mechanism 205 has, for example, a hole (such as a slit) extending in the vertical direction. As a result, the semiconductor element vertical movement mechanism 205 can move the dark field STEM semiconductor element 204 in the vertical direction. Specifically, the dark field STEM semiconductor element 204 is moved along a hole extending in the vertical direction, and the height of the dark field STEM semiconductor element 204 is adjusted to a predetermined (arbitrary) position (moved up and down). The height of the detection surface can be fixed and determined by a fixture 206 (screw structure or the like).

  For example, a scale serving as a standard for height is described on the support 205a of the semiconductor element vertical movement mechanism 205, and the detection angle can be controlled based on the value of the scale. Further, for example, a graph showing the relationship between the height of the dark field STEM semiconductor element 204 and the detection angle may be prepared, and the height may be set while referring to it, or the detection angle value may be directly set in the semiconductor element vertical movement mechanism 205. May be labeled.

  When the sample holder 21 is mounted on the first stage 211, the signal terminal 207 is connected to the second stage 212. The dark field STEM semiconductor element 204 is connected to the signal terminal 207 by wiring (not shown). The signal obtained by the dark field STEM semiconductor element 204 is sent to an amplifier (not shown) of the charged particle beam apparatus 10 via the signal terminal 207 and the second stage 212, and after adjusting the brightness by the amplifier, Become.

  The signal terminal 207 and the sample holder main body 201 are electrically insulated by an insulating material 208. That is, the first stage 211 and the second stage 212 are electrically insulated. The sample holder main body 201 is connected to the first stage 211 via the lower member 201c, and the first stage 211 is connected to the ground. In contrast to the above-described configuration, it is also possible to connect the dark field STEM semiconductor element 204 to the sample holder main body 201 by wiring. In this case, the sample holder main body 201 transmits a signal via the first stage 211. The signal terminal 207 is connected to the ground via the second stage 212.

  The dark field STEM semiconductor element 204 is provided with an opening 204a through which signal particles (bright field STEM signal particles 18a and 18c in FIG. 2) that have passed through the sample 14 without being scattered can pass. The sample holder main body 201 and the first stage 211 are also provided with openings 201d and 211a through which signal particles transmitted through the sample 14 can pass.

  The bright field STEM signal particles 18a that have passed through the opening 204a of the dark field STEM semiconductor element 204, the opening 201d of the sample holder body 201, and the opening 211a of the first stage 211 are bright fields provided below the first stage 211. Detected by the STEM semiconductor element 210. The bright field STEM semiconductor element 210 corresponds to the transmission signal detector 17 of FIG. A bright-field stop 209 is disposed between the first stage 211 and the bright-field STEM semiconductor element 210, and the optimum contrast that has passed through the bright-field stop 209 among the transmitted signal particles (bright-field STEM signal particles). Only bright-field STEM signal particles 18a that are obtained by the bright-field STEM semiconductor element 210 are detected. Note that reference numeral 18 c in FIG. 2 indicates bright field STEM signal particles that have not passed through the bright field stop 209. The bright field stop 209 has a plurality of openings with different hole diameters, and these openings can be switched from outside the vacuum.

  As described above, according to the present example, the secondary signal particles generated from the surface of the sample 14, the dark field STEM signal particles scattered and transmitted in the sample 14, and the sample 14 transmitted without being scattered. The bright field STEM signal particles can be detected separately from each other, and the detection angles of the dark field STEM signal particles and the bright field STEM signal particles can be controlled. A sample image can be observed.

  Further, in the configuration of the present embodiment, since the sample 14 is arranged in the strong magnetic field of the objective lens, the charged particle beam apparatus equivalent to the in-lens type objective lens that similarly arranges the sample in the objective lens magnetic field is adopted. It is possible to employ a stage for a large sample that has high resolution and is difficult to realize with an in-lens objective lens.

  In detecting dark field STEM signal particles, it is known that optimization of the detection scattering angle is extremely important depending on the type of sample (observation target). The reason for this will be described with reference to FIG. FIG. 3 is a diagram schematically showing the relationship between the transmission electron signal intensity and the scattering angle for different materials (atomic number, sample thickness, etc.). In FIG. 3, graph A and graph B represent the case of a light element (or thin sample) and a heavy element (or thick sample), respectively. If the thickness of the sample is substantially uniform, the graph A and the graph B depend on the difference in atomic number.

  In FIG. 3, when a dark field STEM signal having a scattering angle of θ1 or more is detected, the signal sum (hatched area) of graph A is larger than B, and the area of A is larger than B as a dark field image. Bright contrast. On the other hand, if the lower limit of the detection scattering angle is θ2, the signal sum of heavier element B is larger than the signal sum of A, so that B has a brighter contrast than the region A as a dark field image. Thus, by selecting an appropriate detection scattering angle with respect to the relationship between the detection scattering angle and the transmission signal intensity determined by the material of the sample, it is possible to obtain a dark field image having a contrast suitable for the purpose.

  FIG. 4 is a chart showing a sample observation process using the charged particle beam apparatus 10. First, in step 301, a mesh on which the sample 14 is placed is mounted on the sample mounting position 202 of the upper member 201b of the sample holder main body 201.

  Next, in step 302, the height of the dark field STEM semiconductor element 204 is adjusted by the semiconductor element vertical movement mechanism 205, and the position (height) of the dark field STEM semiconductor element 204 is fixed. Note that the steps 301 and 302 may be reversed.

  Next, in step 303, the sample holder 21 is disposed (mounted) on the first stage 211 of the charged particle beam apparatus 10, and the sample is exchanged. Next, in step 304, the charged particle beam apparatus 10 irradiates the sample 14 with the primary charged particle beam 203 and performs STEM observation. In step 305, the image quality is determined from the obtained image. If it is not necessary to change the detection angle, the process proceeds to step 306, and the image is acquired as it is.

  On the other hand, if it is determined in step 305 that the detection angle needs to be changed, in step 307, the sample holder 21 is taken out and the sample is exchanged. Thereafter, returning to step 302, the height of the dark field STEM semiconductor element 204 is changed. Thereafter, in step 303, the sample holder 21 is placed on the first stage 211, and in step 304, STEM observation is performed.

  Hereinafter, the effect of the present embodiment will be described. For example, in the conventional patent document 1 and the patent document 2, there existed the following subjects on the structure.

(1) In the case of the Lower secondary conversion type dark field STEM holder of Patent Document 1, the signal loss and dark field STEM signal at the time of secondary electron conversion of dark field STEM signal electrons by the dark field STEM signal conversion electrode (reflector) The signal loss until the secondary electrons generated from the conversion electrode are taken into the detector results in a decrease in the S / N of the dark field STEM image.

(2) In the case of the lower secondary conversion dark field STEM holder of Patent Document 1, transmitted electrons (particularly bright field STEM signals) are transmitted not only to the dark field STEM signal conversion electrode but also to the holder, detector, and members in the sample chamber. Collisions and secondary electrons are generated from them. When these are detected by the lower detector, the noise component increases, resulting in a decrease in the contrast of the dark field STEM image.

(3) In the case of the lower secondary conversion dark field STEM holder of Patent Document 1, the detection angle is controlled by replacing the dark field STEM signal conversion electrode with the holder body. There are four types of conversion electrodes in the existing products, but it is impossible to finely control the detection angle and observe changes in image quality in detail unless the inner and outer diameters of the conversion electrodes are changed.

(4) The in-lens SEM of Patent Document 2 is a type of SEM in which a large stage mechanism does not exist directly below a sample holder. Therefore, the technique of Patent Document 2 cannot be applied to a charged particle beam apparatus in which a sample holder is disposed on a stage mechanism, such as a semi-in lens SEM or an out lens SEM.

  On the other hand, according to the present embodiment, the dark field STEM signal particles are directly detected by the dark field STEM semiconductor element 204 provided in the sample holder 21, so that the signal loss due to the reflector and the signal until it is taken in by the detector. There is no loss. Further, since the dark field STEM signal particles are directly detected by the dark field STEM semiconductor element 204 provided in the sample holder 21, there is little mixing of noise, and the S / N of the obtained dark field STEM image is high. As described above, when the S / N ratio is improved, an image can be easily formed even if the detection angle width is small. Further, by limiting the width of the detection angle, it becomes easy to form a characteristic image with different information.

  Furthermore, by directly detecting dark field STEM signal particles by a semiconductor element, noise components derived from BF-STEM signal electrons (mixing into the dark field STEM image) can be reduced, and high-contrast observation of the dark field STEM image can be realized. Further, in a charged particle beam apparatus in which a sample holder is disposed on a stage mechanism, such as an out lens SEM or a semi-in lens SEM, the semiconductor element vertical movement mechanism 205 of this embodiment can be used. By moving the dark field STEM semiconductor element 204 up and down by the semiconductor element vertical movement mechanism 205, dark field STEM images with different detection angles can be acquired. Therefore, also in the out-lens SEM and the semi-in-lens SEM, the detection angle can be controlled like the bright-field / dark-field STEM detector of the in-lens SEM (Patent Document 2). If the sample holder 21 of this embodiment is used, there is no need to prepare an expensive dedicated detector for the dark field STEM.

<Second embodiment>
The charged particle beam apparatus according to the second embodiment will be described below. As described above, the signal obtained by the dark field STEM semiconductor element 204 is sent to the amplifier (not shown) of the charged particle beam apparatus 10 via the signal terminal 207 and the second stage 212, and the brightness is adjusted by the amplifier. It becomes an image after being done.

  Here, a dedicated amplifier may be prepared as an amplifier for amplifying the dark field STEM signal. However, in this embodiment, an amplifier of an EBIC (Electron Beam Induced Current) system is used. By using the EBIC amplifier and the configuration of the sample holder 21 including the dark field STEM semiconductor element 204 described above, a dark field transmission image can be observed.

  A general detector (ET detector) used in an electron microscope (especially SEM) collides signal electrons generated from a sample with a phosphor, converts the electrons into light, and then passes the light into a photomultiplier tube through a light guide. It is converted to electrons again on the photoelectric conversion surface. These electrons collide with the dynode electrode to repeat amplification (the role of the amplifier), and are finally taken out as a signal current.

  On the other hand, the EBIC amplifier is for detecting and amplifying a weak electromotive force (signal current) generated in a sample as an absorption current. When a sample is irradiated with an electron beam, some of the incident electrons are absorbed inside the sample. However, in the case of a semiconductor sample, if a PN junction exists on the observation surface, a current is generated in the diffusion portion and an electromotive force is generated. The EBIC image is an image formed using the electromotive force generated in this way. Since the signal current (electromotive force) usually obtained is very small, it is necessary to amplify using a high sensitivity and low noise amplifier.

  The charged particle beam apparatus of the present embodiment includes a sample holder 21 on which a dark field STEM semiconductor element 204 is mounted, and a second sample holder (sample holder on which a sample is mounted) for the EBIC system. The above-described EBIC amplifier is configured to be connectable to the sample holder 21 and the second sample holder for the EBIC system. That is, when the sample holder 21 is mounted on the sample stage mechanism 16, the EBIC amplifier and the dark field STEM semiconductor element 204 are connected. On the other hand, when the second sample holder for the EBIC system is mounted on the sample stage mechanism 16, the EBIC amplifier and the second sample holder for the EBIC system are connected. As a result, the image is displayed with different control depending on the connection destination of the EBIC amplifier.

  For example, when the sample holder 21 on which the dark field STEM semiconductor element 204 is mounted and the EBIC amplifier are connected, the charged particle beam apparatus 10 displays a dark field STEM image. On the other hand, when the EBIC system sample holder and the EBIC amplifier are connected, the charged particle beam device 10 displays an EBIC image. In this way, a common amplifier can be used for detection of dark field signal particles and detection in EBIC. In the present embodiment, the EBIC and the dark field STEM observation can be selectively used only by replacing the holder without requiring a dedicated detector.

<Third embodiment>
The charged particle beam apparatus according to the third embodiment will be described below. FIG. 5 is a schematic configuration diagram of a sample holder of the charged particle beam apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected about the same component as the Example mentioned above in 3rd Example, and description is abbreviate | omitted. In the following, only the parts different in configuration from the above-described embodiment will be described.

  In this embodiment, the sample holder 500 includes a sample holder main body 501 and a cover structure 504 that covers the dark field STEM semiconductor element 204 and the semiconductor element vertical movement mechanism 205. The cover structure 504 may cover the dark field STEM semiconductor element 204 and may be cylindrical or box-shaped. The upper surface 504a of the cover structure 504 has a sample mounting position 502, and a mechanism for mounting or fixing a mesh or the like on which the sample 14 is placed is provided at the sample mounting position 502. The cover structure 504 is a separation structure that can be detached from the sample holder main body 501. Therefore, the sample 14 can be detached only on the cover structure 504 side with the cover structure 504 removed. Thereby, even if the sample 14 is accidentally dropped, it does not fall on the dark field STEM semiconductor element 204, and the risk of damage to the dark field STEM semiconductor element 204 can be reduced.

  In this embodiment, the cover structure 504 covers the semiconductor element vertical movement mechanism 205. However, it is sufficient that at least the dark field STEM semiconductor element 204 is covered, and the semiconductor element vertical movement mechanism 205 is located outside the cover structure 504. The structure which is located may be sufficient.

  Similarly to the first embodiment, the dark field STEM semiconductor element 204 is connected to the semiconductor element vertical movement mechanism 205 via the fixture 206, and the height of the dark field STEM semiconductor element 204 can be adjusted. Has been. As described above, the dark field STEM semiconductor element 204 can be moved up and down even when the cover structure 504 is attached to the sample holder main body 501 or removed.

  For example, when the sample holder 500 is evacuated (depressurized) in the sample chamber, the pressure is not concentrated on the sample mounting portion (mesh on which the sample is placed), and the cover structure 504 can be sufficiently evacuated, for example, The cover structure 504 may be provided with an opening by a slit or the like.

  As another example, the semiconductor element vertical movement mechanism 205 and the cover structure 504 may be integrally formed. In this case, a hole (slit) extending in the vertical direction is provided on the side surface of the cover structure 504, and the dark field STEM semiconductor element 204 is fixed at a predetermined height by the fixture 206.

  In this embodiment, by covering the dark field STEM semiconductor element 204 with the cover structure 504, characteristic X-rays (system peaks) generated from the dark field STEM semiconductor element 204 below the sample 14, the sample holder main body 501 and the like are EDX. It is not detected by the detector. Note that when electrons are scattered inside the cover structure 504 and problems such as noise and system peaks occur, carbon or the like can be applied to the inner surface 504b of the cover structure 504 to suppress electron scattering. Further, the same effect can be expected by making the cover structure 504 itself made of carbon. Further, system peaks generated on the upper surface 504a of the cover structure 504 are similarly avoided by applying carbon to the upper surface 504a and the side surface 504c (that is, the outer surface) of the cover structure 504, or by the carbon cover structure 504. be able to.

  Hereinafter, the effect of the present embodiment will be described. For example, the conventional patent document 1 has the following problems due to its configuration. In the case of the lower secondary conversion dark field STEM holder of Patent Document 1, a system peak due to characteristic X-rays generated when dark field STEM signal electrons collide with the conversion electrode during EDX analysis becomes a problem. The system peak means that characteristic X-rays other than elements contained in the electron beam irradiation point on the sample are detected due to the apparatus.

  According to the present embodiment, by covering the dark field STEM semiconductor element 204 with the cover structure 504, characteristic X-rays (system peaks) generated from the dark field STEM semiconductor element 204 below the sample 14, the sample holder main body 501 and the like can be obtained. It is not detected by the EDX detector, and the system peak problem can be solved. Further, by applying carbon to the cover structure 504 or using the cover structure 504 made of carbon, system peaks that occur on the inner surface and the outer surface of the cover structure 504 can be avoided.

<Fourth embodiment>
The charged particle beam apparatus according to the fourth embodiment will be described below. FIG. 6 is a schematic configuration diagram of a sample holder of the charged particle beam apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected about the same component as the Example mentioned above in 4th Example, and description is abbreviate | omitted. In the following, only the parts different in configuration from the above-described embodiment will be described.

  In the example shown in FIG. 1, a transmission signal detector (bright field STEM detector) 17 and a diaphragm 19 are arranged below the sample stage mechanism 16 in order to perform dark field STEM observation and bright field STEM observation at the same time. Yes. Further, in order for the bright field STEM signal to reach the detector, openings (passing holes) 201d and 211a are required in the bottom of the sample holder main body 201 and the first stage 211 (see the first embodiment). However, depending on the type of charged particle beam apparatus, there is a configuration in which a bright field STEM signal passage hole does not exist in the sample stage mechanism, and in order to perform simultaneous observation of dark field STEM observation and bright field STEM observation, Design changes and major modifications are required. Below, the structure which performs simultaneous observation of dark field STEM observation and bright field STEM observation, without making such a design change or modification is demonstrated.

  The sample holder 600 of this embodiment includes a sample holder main body 501 and a cover structure 504 that covers the dark field STEM semiconductor element 204 and the semiconductor element vertical movement mechanism 205. The structure of the cover structure 504 is the same as that of the third embodiment. The cover structure 504 includes a bright field stop 601 at a position below the dark field STEM semiconductor element 204. Further, a bright field STEM semiconductor element (bright field STEM detector) 602 is disposed in the sample holder main body 501. The bright field stop 601 is disposed between the dark field STEM semiconductor element 204 and the bright field STEM semiconductor element 602. The bright field stop 601 is provided with a hole of several mm in order to detect electrons having a small scattering angle among transmitted electrons, and functions to cut electrons outside the holes.

  The bright field STEM semiconductor element 602 detects bright field STEM signal particles that have passed through the bright field stop 601. Thus, by adding the bright field stop 601 and the bright field STEM semiconductor element 602 to the sample holder 600, it is possible to acquire a bright field STEM image reflecting information on the thickness, density, and crystal structure of the sample. Further, by using together with the dark field STEM semiconductor element 204, simultaneous observation of the bright field STEM and the dark field STEM becomes possible. According to the present embodiment, the bright field STEM signal can be detected even if the sample holder and the sample stage mechanism do not have an opening (a passage hole for the bright field STEM signal).

  In the above-described example, the bright field stop 601 is attached to the cover structure 504, but the present invention is not limited to this configuration. A mechanism for supporting the bright field stop 601 may be provided separately from the cover structure 504. Further, the cover structure 504 is not always necessary, and the bright field stop 601 and the bright field STEM semiconductor element 602 may be attached to the sample holder main body 201 as in the example of FIG.

<Fifth embodiment>
The charged particle beam apparatus according to the fifth embodiment will be described below. FIG. 7 is a schematic configuration diagram of a sample holder of the charged particle beam apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected about the same component as the Example mentioned above in 5th Example, and description is abbreviate | omitted. In the following, only the parts different in configuration from the above-described embodiment will be described.

  A bright field STEM semiconductor element 701 is disposed in the sample holder main body 501. In the example of FIG. 6, the bright field stop 601 serves to cut electrons outside the hole. However, in this embodiment, the size of the bright field STEM semiconductor element 701 is limited. For example, by limiting the bright field STEM semiconductor element 701 to the same diameter (several millimeters) as the diameter of the diaphragm, the diaphragm mechanism becomes unnecessary, and the same effect (observation result) as the configuration of FIG. 6 can be obtained.

  As a configuration for limiting the size of the bright field STEM semiconductor element 701, (1) the size of the bright field STEM semiconductor element 701 itself may be reduced, or (2) the upper surface of the bright field STEM semiconductor element 701 is narrowed down. The structure may be masked to limit bright field STEM signal particles that pass through the masking process. That is, in the case of (1), the bright-field STEM semiconductor element 701 is formed with a diameter (a diameter approximately the same as that of the diaphragm) that can detect bright-field STEM signal particles that have passed through the dark-field STEM semiconductor element 204 at a predetermined detection angle. ing. In the case of (2), the surface of the bright field STEM semiconductor element 701 has a diameter (a diameter comparable to that of the diaphragm) that can detect bright field STEM signal particles that have passed through the dark field STEM semiconductor element 204 at a predetermined detection angle. It is masked to leave. In this configuration, the bright field STEM semiconductor element 701 and the aperture function can be integrally configured by mask processing.

  According to the present embodiment, the bright field STEM and the dark field STEM can be observed simultaneously even if the sample holder and the sample stage mechanism do not have an opening (a passage hole for a bright field STEM signal). In addition, by limiting the size of the bright field STEM semiconductor element 701, it is possible to detect a signal at a specific angle of the bright field STEM without providing a diaphragm mechanism separately from the bright field STEM semiconductor element 701. . Further, the cover structure 504 is not always necessary, and the bright field STEM semiconductor element 701 may be provided on the sample holder main body 201 as in the example of FIG.

<Sixth embodiment>
The charged particle beam apparatus according to the sixth embodiment will be described below. FIG. 8 is a schematic configuration diagram of a sample holder of the charged particle beam apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected about the same component as the Example mentioned above in 6th Example, and description is abbreviate | omitted. In the following, only the parts different in configuration from the above-described embodiment will be described.

  In the embodiment described above, the dark field STEM semiconductor element 204 and the bright field STEM semiconductor elements 602 and 701 are provided separately, but a plurality of bright field STEM semiconductor elements are arranged in a part of the dark field STEM semiconductor element. (Bright-field and dark-field integrated semiconductor device).

  For example, the dark field STEM semiconductor element 204 is connected to the semiconductor element vertical movement mechanism 205 via a support portion 801 having a predetermined length. The support portion 801 may be attached to the cover structure instead of the semiconductor element vertical movement mechanism 205.

  A plurality of bright field STEM semiconductor elements 802 having different diameters are arranged on the support portion 801 of the dark field STEM semiconductor element 204. Further, the support column 205a of the semiconductor element vertical movement mechanism 205 has a movement mechanism capable of moving the support portion 801 in and out in the horizontal direction. In this way, by moving the support portion 801 in the lateral direction, the plurality of bright field STEM semiconductor elements 802 are aligned with positions where the bright field STEM signal particles are detected. With this configuration, bright field STEM observation by the bright field STEM semiconductor element 802 can be performed at the same height as the dark field STEM semiconductor element 204.

  In this example, a plurality of bright field STEM semiconductor elements 802 having different diameters are arranged along the moving direction (stroke direction) of the support portion 801. By moving the support portion 801, a plurality of bright field STEM semiconductor elements 802 having different diameters can be used properly, and bright field signals having different detection angles can be acquired. That is, by using a plurality of bright field STEM semiconductor elements 802 having different diameters, the same effect as the above-described bright field stop can be expected. In the prior art, a bright field holder, a dark field holder, a dark field detector, a bright field detector, and a bright field stop (including aperture diameter change) are individually provided. The sample holder can perform all functions.

<Seventh embodiment>
The charged particle beam apparatus according to the seventh embodiment will be described below. The dark field STEM semiconductor element 204 of the above-described embodiment is configured to be removable from the sample holder 21. Therefore, hereinafter, a configuration in which a plurality of dark field STEM semiconductor elements 204 are prepared and the dark field STEM semiconductor elements 204 are replaced will be described.

  It is known from the calculation results that a detection angle of about 1000 mrad can be expected if the dark field STEM semiconductor element 204 is moved to the uppermost position by using the semiconductor element vertical movement mechanism 205 of the first embodiment. The dark field STEM semiconductor element 204 may be changed to an element having a larger outer diameter. In this case, a detection angle of 1000 mrad or more can be detected. Further, the inner diameter may be calculated according to the outer diameter of the dark field STEM semiconductor element 204 to limit the width of the detection angle. This makes it easy to form characteristic images with different information.

  A method of increasing only the outer diameter of the dark field STEM semiconductor element 204 is also conceivable. By increasing only the outer diameter, the width of the detection angle becomes very large, and a dark field STEM image with a large amount of information with a rich S / N can be acquired. If a large detection element can be mounted, the possibility of image formation increases even in a composite material sample mainly composed of heavy elements, which has been difficult to observe conventionally.

  On the other hand, the dark field STEM semiconductor element 204 may be changed to a semiconductor element having a different P layer or N layer thickness. In this case, the detection sensitivity of the semiconductor element can be changed (which may be the P layer or the N layer, but the sensitivity improves as the detection surface of the charged signal particles is thinner, that is, the sensitivity is obtained even at a low acceleration voltage). For example, when targeting low acceleration, a low acceleration voltage dark field STEM signal can be detected by mounting a detection element having a thin P layer or N layer of a semiconductor element.

  As described above, the dark field STEM semiconductor element 204 has a plurality of types so as to include a plurality of first semiconductor elements having different diameters and a plurality of second semiconductor elements having different P layer or N layer thicknesses. It may be configured. The dark field STEM semiconductor element 204 is configured to be attached to the sample holder from the first semiconductor element or the second semiconductor element to obtain different signal information.

  By using a plurality of types of dark field STEM semiconductor elements 204 as described above, high-contrast STEM observation is possible even for a composite material sample mainly composed of light elements such as a soft material. Conventionally, a staining method is used prior to observation for a sample in which contrast is difficult to obtain with a TEM or STEM, such as a biological sample such as a biological tissue or a cell, but it is expensive if high contrast STEM observation can be realized at a low acceleration voltage. The need for staining that requires staining solutions and advanced techniques is reduced.

<Eighth embodiment>
The charged particle beam apparatus according to the eighth embodiment will be described below. FIG. 9 is a schematic configuration diagram of a sample holder of the charged particle beam apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected about the same component as the Example mentioned above in 8th Example, and description is abbreviate | omitted. In the following, only the parts different in configuration from the above-described embodiment will be described.

  In the following, in the sample holder 900, a configuration in which the dark field STEM semiconductor element 204 is driven up and down in a vacuum (sample chamber) without taking the sample holder 900 into the atmosphere will be described. FIG. 9 is a top view of the sample holder of the charged particle beam apparatus according to the present embodiment, and FIG. 10 is a cross-sectional view of the sample holder of the charged particle beam apparatus according to the present embodiment.

  In the present embodiment, the cover structure 504 of the sample holder 900 includes a cylindrical Faraday cup structure (detection mechanism) 901 and an actuator and gear mechanism (drive mechanism) 902. In the Faraday cup structure 901, a current corresponding to the number of charged particles flows, and thereby signal particles of the charged particle beam can be detected. The actuator and gear mechanism 902 is connected to the Faraday cup structure 901 and detects and drives the voltage (acceleration voltage) of the charged particle beam 903 irradiated to the Faraday cup structure 901. The semiconductor element vertical movement mechanism 205 is connected to an actuator and gear mechanism 902. Here, when the charged particle beam 903 is irradiated to the Faraday cup structure, the dark field STEM semiconductor element 204 is moved up and down by the semiconductor element vertical movement mechanism 205.

  The actuator and gear mechanism 902 includes a piezoelectric element (not shown), and the actuator and gear mechanism 902 detects the voltage (acceleration voltage) of the charged particle beam 903 irradiated to the Faraday cup structure 901 to detect the drive source. Operate the piezoelectric element of the actuator. For driving, expansion / contraction of the piezoelectric element of the actuator may be used, or a mechanism for moving a gear or the like using the actuator as a switch may be used. Thereby, the semiconductor element vertical movement mechanism 205 of the sample holder 900 can be moved in a vacuum.

  The charged particle beam irradiation conditions are changed according to the vertical movement of the dark field STEM semiconductor element 204. For example, the vertical driving of the semiconductor element vertical movement mechanism 205 can be controlled by setting the acceleration voltage to 15 kV or higher when increasing and lower than 15 kV when decreasing.

  In addition, for example, a cylindrical insulating material 905 is disposed around the Faraday cup structure 901, and the Faraday cup structure 901 is electrically insulated from the cover structure 504. Thereby, even if the charged particle beam 903 is irradiated to the sample holder 900 or the cover structure 504, the actuator does not operate.

  The charged particle beam irradiation position of the Faraday cup structure 901 and the sample mounting position 502 can store stage coordinates in a storage device (not shown) of the charged particle beam apparatus 10. For example, by operating the operation screen of the charged particle beam apparatus, the irradiation position of the charged particle beam 903 is moved between the position of the Faraday cup structure 901 and the sample mounting position 502, and the optimum conditions for observation (in particular, dark field) The height of the STEM semiconductor element can be found.

  In this embodiment, by irradiating the charged particle beam 903 to the Faraday cup structure 901, the semiconductor element vertical movement mechanism 205 can be driven and the detection angle can be controlled. A sample image having an optimum contrast according to the sample and the purpose can be observed, and the operability is improved because the sample holder 900 does not need to be exposed to the atmosphere.

  FIG. 11 is a chart showing a sample observation process using the charged particle beam apparatus according to the present embodiment. First, in step 1101, a mesh on which the sample 14 is placed is mounted on the sample mounting position 502.

  Next, in step 1102, the height of the dark field STEM semiconductor element 204 is adjusted by the semiconductor element vertical movement mechanism 205 to adjust the position (height) of the dark field STEM semiconductor element 204. Note that the procedures of steps 1101 and 1102 may be reversed.

  Next, in step 1103, the sample holder 900 is disposed (mounted) on the first stage 211 of the charged particle beam apparatus 10, and the sample is exchanged. Next, in step 1104, STEM observation is performed by the charged particle beam apparatus 10. In step 1105, the image quality is determined from the obtained image. If it is not necessary to change the detection angle, the process proceeds to step 1106, and the image is acquired as it is.

  On the other hand, if it is determined in step 1105 that the detection angle needs to be changed, the irradiation position of the charged particle beam 903 is moved to the position of the Faraday cup structure 901 in step 1107, and the charged particle beam 903 is irradiated. Then, the semiconductor element vertical movement mechanism 205 is driven. As a result, the dark field STEM semiconductor element 204 is raised or lowered. Thereafter, returning to step 1104, the irradiation position of the charged particle beam 903 is moved to the sample mounting position 502, and STEM observation is performed again by the charged particle beam apparatus 10. In this embodiment, the dark field STEM semiconductor element 204 can be driven up and down in a vacuum (sample chamber) 904 without taking the sample holder 900 into the atmosphere.

<Ninth embodiment>
The charged particle beam apparatus according to the ninth embodiment will be described below. FIG. 12 is a schematic configuration diagram of a sample holder of the charged particle beam apparatus according to the present embodiment. In addition, the same code | symbol is attached | subjected about the same component as the Example mentioned above in 9th Example, and description is abbreviate | omitted. In the following, only the parts different in configuration from the above-described embodiment will be described.

  Conventionally, the reflection signal generated from the sample is detected by inserting a dedicated reflection signal detector between the objective lens and the sample or using a reflection signal detector incorporated in the objective lens. In this embodiment, a configuration in which a reflected signal is detected by a reflected signal element integrated with a sample holder will be described. The detection mechanism in this embodiment is the same as that in the first embodiment, but the signal detected in this embodiment is a reflective particle. The sample 14 may be a thin film or a bulk sample.

  The sample holder 1200 of this embodiment includes a dark field STEM semiconductor element 1204 and a semiconductor detection element vertical movement mechanism 1205. The dark field STEM semiconductor element 1204 has the same configuration as the dark field STEM semiconductor element 204 described above. The semiconductor detection element vertical movement mechanism 1205 includes a support column 1205a. Unlike the first embodiment, the column 1205a of this embodiment is set so that its length extends to a position higher than the upper member 201b of the sample holder main body 201. Further, the support column 1205a is configured to be removable from the sample holder main body 201.

  In this example, the dark field STEM semiconductor element 1204 is moved to the lowest position using the semiconductor detection element vertical movement mechanism 1205, and the column 1205 a of the semiconductor detection element vertical movement mechanism 1205 is removed from the sample holder main body 201. The column 1205a is turned upside down, and the column 1205a is attached to the sample holder main body 201 again. By doing so, the dark field STEM semiconductor element 1204 is positioned above the sample mounting position 202 of the sample holder body 201 as shown in FIG. Thus, the dark field STEM semiconductor element 1204 can be used as a reflected signal semiconductor element.

  The primary charged particle beam 1202 focused by the objective lens 1201 passes through the opening of the dark field STEM semiconductor element 1204 and is irradiated to the sample mounted at the sample mounting position 202. Reflective particles 1203 generated therefrom are detected by a dark field STEM semiconductor element 1204 as a reflection signal element. The process and path from the signal detected by the dark field STEM semiconductor element 1204 to image formation are the same as in the first embodiment.

  According to the present embodiment, it is possible to use the dark field STEM semiconductor element 1204 attached to the semiconductor detection element vertical movement mechanism 1205 as a reflected signal element. In particular, one dark field STEM semiconductor element 1204 can perform both dark field STEM observation and reflection signal detection.

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

  In the above embodiment, a semiconductor element is used as an element for detecting the dark field STEM signal, the bright field STEM signal, and the reflection signal. The element for detecting each charged particle is not limited to a semiconductor element, but is a scintillator / photomal type detection system used in a secondary electron detector of a scanning electron microscope, a fluorescent plate used in a transmission electron microscope, or a CCD camera. It may be a system. The process and path from when a signal is detected until image formation is the same as in a conventional scanning electron microscope and transmission electron microscope.

10: charged particle beam apparatus 14: sample 15: dark field STEM semiconductor element 16: sample stage mechanism 17: transmission signal detector 21: sample holder 201: sample holder body 202: sample mounting position 204: dark field STEM semiconductor element 205: Semiconductor element vertical movement mechanism 210: Bright field STEM semiconductor element 500: Sample holder 501: Sample holder body 502: Sample mounting position 504: Cover structure 600: Sample holder 601: Bright field stop 602: Bright field STEM semiconductor element 701: Bright field STEM semiconductor element 801: support part 802: bright field STEM semiconductor element 900: sample holder 901: Faraday cup structure 902: actuator and gear mechanism 1200: sample holder 1201: objective lens 1202: primary charged particle beam 1203: reflective particle 120 4: Dark field STEM semiconductor element 1205: Semiconductor detection element vertical movement mechanism 1205a: Support column

Claims (17)

In a charged particle beam device that is an out-lens SEM or a semi-in-lens SEM, comprising a stage mechanism and a sample holder disposed on the stage mechanism,
A dark field STEM semiconductor element that directly detects dark field STEM signal particles transmitted through the sample mounted on the sample holder; a moving mechanism that moves the dark field STEM semiconductor element in the vertical direction; and A charged particle beam apparatus comprising: a cover structure that covers a field-of-view STEM semiconductor element. The charged particle beam apparatus according to claim 1,
The charged particle beam apparatus, wherein the cover structure has a structure for mounting or fixing a mesh on which a sample is placed. In the charged particle beam device according to claim 1 or 2,
The charged particle beam apparatus characterized in that the cover structure is removable from the main body of the sample holder. In the charged particle beam device according to any one of claims 1 to 3,
A charged particle beam apparatus, wherein a scale is described on a support column of the moving mechanism. In the charged particle beam device according to any one of claims 1 to 4,
The charged particle beam apparatus, wherein the cover structure includes the moving mechanism for moving the dark field STEM semiconductor element in a vertical direction. In the charged particle beam device according to any one of claims 1 to 5,
A charged particle beam apparatus, wherein carbon is applied to an inner surface or an outer surface of the cover structure, or the cover structure is formed of carbon. In the charged particle beam device according to any one of claims 1 to 6,
The dark field STEM semiconductor element and the stage mechanism have an aperture through which bright field STEM signal particles can pass,
The charged particle beam apparatus includes a bright field STEM detector disposed below the stage mechanism,
The charged particle beam apparatus, wherein the bright field STEM detector can detect bright field STEM signal particles that have passed through the dark field STEM semiconductor element and the stage mechanism. In the charged particle beam device according to any one of claims 1 to 6,
The dark field STEM semiconductor element has an opening through which bright field STEM signal particles can pass,
The sample holder includes a bright field STEM detector disposed below the dark field STEM semiconductor element,
The charged particle beam apparatus, wherein the bright field STEM detector is capable of detecting bright field STEM signal particles that have passed through the dark field STEM semiconductor element. In the charged particle beam device according to any one of claims 1 to 8,
The charged particle beam device is a semi-in-lens SEM,
A charged particle beam apparatus characterized in that a sample is placed in an objective lens magnetic field. In the charged particle beam device according to any one of claims 1 to 9,
The sample holder is
A detection mechanism for detecting signal particles of a charged particle beam;
A driving mechanism connected to the detection mechanism and driving the moving mechanism;
With
A charged particle beam apparatus, wherein the dark field STEM semiconductor element is moved in the vertical direction by irradiating the position of the detection mechanism with the charged particle beam. In the charged particle beam device according to any one of claims 1 to 9,
The moving mechanism includes a columnar member extending to a position higher than the sample mounting position of the sample holder,
The dark field STEM semiconductor element is fixed at a position higher than the sample mounting position of the sample holder in the columnar member, so that the dark field STEM semiconductor element can detect the reflective particles reflected from the sample. A charged particle beam device characterized by comprising. In the charged particle beam device according to any one of claims 1 to 9,
A second sample holder for mounting a sample, the second sample holder being replaceable with the sample holder disposed on the stage mechanism;
An amplifier that detects and amplifies the signal current generated in the sample of the second sample holder as an absorption current,
When the sample holder is disposed on the stage mechanism, the amplifier is connected to the dark field STEM semiconductor element of the sample holder,
When the second sample holder is disposed on the stage mechanism, the amplifier is connected to the second sample holder. An observation method using a charged particle beam device, which is an out-lens SEM or a semi-in-lens SEM, comprising a stage mechanism and a sample holder disposed on the stage mechanism,
Mounting or fixing a mesh carrying a sample on the cover structure of the sample holder;
Moving the dark field STEM semiconductor element vertically by the moving mechanism of the sample holder;
Placing the sample holder on the stage mechanism with the cover structure covering the dark field STEM semiconductor element;
Irradiating the sample on the sample holder with a charged particle beam;
Directly detecting dark field STEM signal particles transmitted through the sample on the sample holder by the dark field STEM semiconductor element;
Including observation method. An observation method using a charged particle beam device, which is an out-lens SEM or a semi-in-lens SEM, comprising a stage mechanism and a sample holder disposed on the stage mechanism,
A dark field STEM semiconductor element that directly detects dark field STEM signal particles, a moving mechanism that moves the dark field STEM semiconductor element, a detection mechanism that detects signal particles of a charged particle beam, and the detection mechanism, Mounting a sample on a sample holder provided with a drive mechanism for driving a moving mechanism;
Placing the sample holder on the stage mechanism;
Moving the dark field STEM semiconductor element in a vertical direction by irradiating a position of the detection mechanism with a charged particle beam to drive the drive mechanism;
Irradiating the sample on the sample holder with a charged particle beam;
And directly detecting dark field STEM signal particles transmitted through the sample on the sample holder by the dark field STEM semiconductor element. An observation method using a charged particle beam device, which is an out-lens SEM or a semi-in-lens SEM, comprising a stage mechanism and a sample holder disposed on the stage mechanism,
By moving the dark-field STEM semiconductor device in the vertical direction by a moving mechanism of the sample holder, the steps of the dark-field STEM semiconductor device of the specimen holder, is fixed at a position higher than the sample mounting position of the sample holder,
Detecting the reflective particles reflected from the sample by the dark field STEM semiconductor element. In the observation method as described in any one of Claims 12-14 ,
An observation method including a step of detecting a bright field STEM signal particle transmitted through the dark field STEM semiconductor element and the opening of the stage mechanism by a bright field STEM detector disposed below the stage mechanism. In the observation method as described in any one of Claims 12-14 ,
An observation method comprising a step of detecting a bright field STEM signal particle transmitted through an opening of the dark field STEM semiconductor element by a bright field STEM detector provided in the sample holder below the dark field STEM semiconductor element.

Images