JP2006194907A - Sample observation device and method using electron beam - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample observation device and a sample observation method capable of irradiating a thinned film sample with an electron beam to be observed, in particular, capable of analyzing an element by X-ray detection, with high precision and high resolution, while reducing background noise. <P>SOLUTION: A member 56 comprising a light element material with a hole part is arranged just behind the thin film sample, and a specific part of the sample 22 is observed with the electron beam 8. In the present invention, an X-ray generated from a portion other than the sample, and the electron beam scattered by the portion other than the sample to get incident again into the sample can be reduced, when irradiating the thin film sample with the electron beam for observation, so as to allow secondary electron image observation and the element analysis of high accuracy and high sensitivity, and the sample observation device and the sample observation method capable of carrying out internal observation of an LSI device or the like getting finer, with the high precision and high resolution. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention particularly relates to a thin film sample, powder observation / analysis / evaluation means, and a semiconductor device and a liquid crystal device that need to observe and analyze not only the surface of the object to be observed but also the internal cross section close to the surface. The present invention relates to an apparatus system used as an observation / analysis / evaluation means in research and development and manufacturing of electronic devices such as magnetic heads and micro devices.

A method for detecting X-rays generated by irradiating an electron beam is known as means for obtaining elemental composition information of a sample. X-rays consist of characteristic X-rays with energy specific to the elements that make up the sample and continuous X-rays below the energy of the incident electron beam due to bremsstrahlung. Knowing the elemental composition of the sample by analyzing the X-ray energy spectrum be able to. JP-A-55-68060 discloses a collimator having an opening smaller than an X-ray detector for taking in X-rays from a sample. (Prior art example 1) A structure which has been further studied is known, and the schematic structure of the apparatus is shown in FIG.
In this configuration, the sample is irradiated with an electron beam, an X-ray detection element provided obliquely above the sample, and a collimator that limits the optical path of the X-ray entering the X-ray detection element between the X-ray detection element and the sample. The X-ray detector has a configuration for detecting X-rays generated from the sample.
FIG. 23 is a schematic enlarged view showing the state around the sample in the in-lens electron microscope shown in FIG. The micro sample 22 is inserted into a space between the upper magnetic pole 707 and the lower magnetic pole 708 constituting the objective lens. The micro sample 22 is held by a mesh 26 and attached to the sample holder 706 via the mesh 26. When the sample 22 is irradiated with the electron beam 8, X-rays 401, secondary electrons 301, and reflected electrons 205 are generated. When X-rays are detected and elemental analysis of a minute sample is performed, it is ideal if only the X-ray 401 is measured. However, in reality, X-rays are generated for various reasons as described below.
A part of the reflected electrons 205 collides with the surface of the upper magnetic pole, and generates X-rays 402 having energy unrelated to the sample. X-rays 403 and 406 are generated when the electron beams 201 and 202 transmitted through the sample collide with the sample holder 706 and the lower magnetic pole 708. X-rays 407 are generated when the reflected electrons 207 obtained by elastically scattering the transmission electron beam 202 by the lower magnetic pole 708 collide with the sample holder 706. X-rays 405 are generated when X-rays generated by transmission electrons 202 colliding with the lower magnetic pole enter the sample holder. Although not shown, there are X-rays generated when reflected electrons and transmitted electrons collide with another part of the sample or mesh. These X-rays are called background X-rays and are not attributed to the sample, and cause deterioration in the accuracy of elemental analysis.
The collimator shown in FIG. 21 is provided to reduce the background X-ray from entering the X-ray detection element as much as possible.
An example of another technique to reduce background x-rays is “Principles of Analytical Electron Microscopy”, David Sea Joy et al., Pages 131-135 1986 Plenciples of New York (“Principles of Analytical Electron Microscopy”, Edited by David C Joy et al., Pp 131-135, 1986, Plenum Press, New York) (Known Example 2).
In this example, as shown in FIG. 24, by installing plates 501 and 502 having holes for transmitting an electron beam made of a light element material on the surfaces of upper and lower magnetic poles, reflected electrons and transmitted electrons from a sample are provided. Has collided directly with a magnetic pole mainly composed of Fe, but collides with a light element plate. As a result, the number of reflected electrons at the magnetic pole, the energy of characteristic X-rays, and the continuous X-ray dose can be reduced. As a result, background X-rays can be reduced.
Japanese Patent Laid-Open No. 8-261894 (Known Example 3) discloses a method for reducing background X-rays generated by reflection electrons and transmission electrons colliding with a portion other than an observation point on a sample. This is because when creating a thin observation surface of the sample, the observation surface is formed so as to be inclined with respect to the side surface of the non-thinned sample, and the surface of the sample portion other than the observation surface is covered with a carbon film. To form.
Furthermore, a method using a sample stage covered with carbon is also known.

JP-A-8-261894

The conventional methods described above have the following problems.
The method of known example 1 is a method in which a collimator is placed between the X-ray detection element and the sample so that X-rays generated from other than the sample do not enter the detection element. There is a problem that the transmission electron beam that has passed through is not effective for the X-rays generated by colliding with the portion of the sample stage directly under the sample. In addition, in order to limit the X-ray only from the electron beam irradiation point on the sample, the method of installing a long and narrow collimator has to increase the distance between the detection element and the sample, so that a large detection solid angle can be obtained. As a result, there was a problem that the detection efficiency was lowered. In addition, the X-ray detector needs to be installed accurately with respect to the sample, and there is a problem in that the detection sensitivity decreases when the position of the sample is shifted.
The method of covering the surface of the upper and lower magnetic poles of the objective lens shown in the known example 2 with a light element material is a sample when the acceleration voltage of the electron beam is high and a very thin sample of 100 nm or less is used like a transmission electron microscope. It is effective when there is little scattering of the electron beam that passes through the sample, but with a general scanning electron microscope or a thick sample of 100 nm or more, the scattering angle of the electron beam that has passed through the sample is large. Background X-rays generated by collision of partial electron beams other than light element materials become large. For this reason, there existed a problem that detection accuracy fell.

  The background X-rays generated by the scattered electrons colliding with parts other than the sample stage and the sample chamber as described above also by the processing method of the micro sample shown in the known example 3 are not taken into consideration. However, the problem that the X-ray from other than the measurement target portion of the sample is detected and the measurement accuracy is lowered has not been sufficiently considered. X-rays generated when a carbon film deposited on a sample is formed and scattered electrons collide with the film are reduced as compared with the case where there is no carbon film, but the degree is not sufficient. In addition, the method of forming a carbon film on a part of a micro sample requires a vapor deposition apparatus, and it is necessary to perform vapor deposition every time a sample is prepared. This causes a problem that sample preparation becomes complicated and time is required.

  Although the method of covering the sample stage with carbon can reduce the signal from the elements that make up the sample stage, there is a problem that characteristic X-rays and continuous X-rays from the coated carbon film are detected and the signal-to-noise ratio is not greatly improved. It was.

  As described above, the problems related to elemental analysis by X-ray detection have been described. However, the reflected electrons generated by the electrons scattered through the sample colliding with other parts are incident again on the part other than the measurement part of the sample. There is a problem in that secondary electrons are generated and are different from the original secondary electron image.

  In view of the above problems, an object of the present application is to provide a sample observation apparatus and a sample observation method that can observe an internal cross section of a target sample in a vertical cross section, and can observe and analyze with high resolution, high accuracy, and high throughput. The object is to provide a sample observation apparatus and a sample observation method that can be observed and analyzed without degradation and failure due to atmospheric exposure.

  The object as described above is achieved by the following.

(1) An electron source, a lens for focusing an electron beam, an electron beam optical system including an electron beam scanning deflector, a sample stage on which a sample is placed, and the sample is irradiated with the electron beam and generated from the sample. In a sample observation apparatus equipped with either or both of an electron beam detector for detecting electrons and an X-ray detector for detecting X-rays, a member (absorbing member) containing a light element material behind the sample and having a hole ) Is placed on a sample stage and has a function of irradiating the electron beam to observe the sample.
As a result, the electron beam transmitted through the thin film sample and incident on the member other than the sample enters the member made of the light element material, so that the generated continuous X-rays and the number of backscattered electrons are reduced. Can be reduced. For this reason, characteristic X-ray spectral peaks corresponding to elements contained in the sample can be detected with a high signal-to-noise ratio relative to the background continuous X-ray spectrum, and the electron beam is transmitted through the sample to other parts. The impact of reflected electrons generated by collisions and secondary electrons and transmitted electrons generated by re-entering a minute sample can be reduced, enabling highly accurate measurement of secondary and reflected electrons and high spatial resolution observation. It becomes. Moreover, since the sample is not taken out of the apparatus, a sample observation apparatus that can observe and analyze in a short time can be provided.

  In elemental analysis based on atomic characteristic X-ray detection at the time of charged particle beam irradiation, it is possible to avoid the expansion of the X-ray generation area due to penetration of the charged particle beam into the sample by thinning the sample. An X-ray generated when an electron beam transmitted through the target sample is incident at a location other than the micro-sample and an electron scattered backward from the location is re-incident on the target sample Since the influence of the line can be reduced, high spatial resolution elemental analysis becomes possible.

Accordingly, it is possible to provide a sample observation apparatus that can observe and analyze the internal cross section of the target sample with high resolution, high accuracy and in a short time.
(2) an ion source, a lens for focusing an ion beam, a focused ion beam optical system including an ion beam scanning deflector, an electron source, a lens for focusing an electron beam, and an electron beam optical system including an electron beam scanning deflector; In a sample observation apparatus including a sample stage on which a sample is placed, a function of separating a second sample from the sample using the focused ion beam, a manipulator for extracting the second sample, and an electron beam are provided. An electron beam detector for irradiating a minute sample to detect electrons generated from the sample, an X-ray detector for detecting X-rays, or both, and behind the extracted second sample A function of observing the second sample with an electron beam by installing a member (absorbing member) containing a light element material and having a hole between the sample stage or the sample stage and the second sample Special features And sample observation apparatus according to.

Thereby, as described above, not only high-resolution observation with high spatial resolution is possible, but also a sample observation apparatus that can observe and analyze in a short time can be provided because the sample is not taken out of the apparatus.
(3) A manipulator for extracting the second sample separated from the introduced sample includes a manipulator control device that drives the manipulator independently of the sample stage, and the second sample is supported by the manipulator. In this state, the sample observation apparatus has a function of changing an irradiation angle of the charged particle beam for observation onto the second sample.

As a result, the position of the sample can be moved with respect to the scanning electron microscope optical system or the focused ion beam optical system while the sample including the portion to be observed is adhered to the manipulator, so that the micro sample can be placed at a position where the observation resolution becomes higher. Can be arranged. Moreover, the internal cross-section observation direction of the target sample can be freely selected. For this reason, if the cross section is observed vertically, it is possible to provide a sample observation apparatus capable of observing with high resolution the shape dimension, embedding condition, film thickness, etc. of etching or flattening, with high accuracy. Moreover, since the sample is not taken out of the apparatus, a sample observation apparatus that can observe and analyze in a short time can be provided.
(4) A space behind the observation sample extracted by the first manipulator by the second manipulator having a light element member at the tip, that is, a space opposite to the device that generates the observation charged particle beam The sample observation apparatus is characterized by being a method of inserting the light element member.

As a result, the influence of backscattered electrons generated when the electron beam that has passed through the sample is incident on a portion other than the sample can be reduced, so that high-resolution observation can be performed, and the sample is not taken out of the apparatus, so that it is short. It is possible to provide a sample observation apparatus that can observe and analyze in time. In elemental analysis based on atomic characteristic X-ray detection at the time of charged particle beam irradiation, it is possible to avoid the expansion of the X-ray generation area due to penetration of the charged particle beam into the sample by thinning the sample. An X-ray generated when an electron beam transmitted through the target sample is incident at a location other than the micro-sample and an electron scattered backward from the location is re-incident on the target sample Since the influence of the line can be reduced, high-resolution elemental analysis is possible.
(5) The observation sample extracted from the introduced sample is placed, and the second sample stage having the light element member according to claim 1 is provided on the sample stage according to claim 1. The sample observation apparatus described is used.

This also makes it possible to provide a sample observation apparatus that can perform high-resolution observation for the reasons described above, and can observe and analyze in a short time. Moreover, the problem of vibration in sample observation can be avoided by fixing the extracted sample in contact with a part of the second sample stage.
(6) A function of placing a sample including an observation target portion extracted from the sample and driving the sample independently from the sample stage according to claim 1 to change the irradiation position and angle of the observation charged beam to the sample. And a third sample stage having the light element member according to claim 1. The sample observation apparatus according to claim 2.

Thereby, the sample observation apparatus which can observe and analyze the object internal cross section of a sample in high resolution and for a short time can be provided. In addition, by separating the extracted sample from the manipulator and fixing a plurality of samples to the second sample stage with one manipulator, the time for cross-sectional observation and elemental analysis can be shortened. Moreover, since the sample is separated from the manipulator and fixed to the second sample stage, the problem of vibration in sample observation can be avoided.
(7) The absorbing member according to claim 1 and claim 2 has a hole, and is installed immediately after the sample, and the ratio of the distance between the sample and the upper surface of the hole and the diameter of the hole is 1/5 or less. A sample observation device.
Thereby, the electron beam which permeate | transmitted this sample injects into the hole of this light element member, and the incident electron collides with the side surface and bottom face of a hole. Since most of the electrons collide with the side surface and are scattered in the direction of the hole bottom, the electrons returning to the surface can be greatly reduced. In addition, the X-rays generated by passing through the sample and entering the hole and colliding with the inner surface of the hole pass through the light element member, arrive at the X-ray detector, and are attenuated when passing through. The influence of X-rays generated in the hole can be reduced. For this reason, the sample observation apparatus which can observe with high precision and high resolution can be provided.
(8) The sample observation apparatus is characterized in that the absorbing member having the hole is covered with a heavy element material.
As a result, X-rays generated by passing through the sample and colliding with the inner surface of the hole are attenuated by the absorbing member made of the light element material, and further, by the heavy element material having a larger attenuation capability covering the outside of the absorbing member. Since it is attenuated, X-rays generated in the hole detected by the X-ray detector can be greatly reduced. For this reason, the sample observation apparatus which can observe with high precision and high resolution can be provided.
(9) A sample observation apparatus in which the light element member is made of carbon, beryllium, or a composite of carbon and beryllium.
In general, when an electron collides with a substance made of an element, X-rays called characteristic X-rays peculiar to the element of the substance and continuous X-rays by bremsstrahlung are generated. Of these, characteristic X-rays are observed as spectral peaks, and the presence of this peak provides information that the element is contained in the sample. It is desirable not to generate from other than the part. As described above, in the present invention, an electron beam transmitted through a thin film sample is incident on a hole of a member made of a light element material disposed immediately after the thin film sample, and X-rays are generated inside the hole. The smaller the X-ray energy, the more X-rays are absorbed by the material and are more susceptible to attenuation. For this reason, the background X-rays can be remarkably reduced especially when it is composed of beryllium or carbon. Also, beryllium has an X-ray energy of 110 eV, which is convenient because it is an X-ray that is not detected by a normal semiconductor detector.
Furthermore, as compared with the case where it collides with a silicon-based wafer or a part made of a metal material that constitutes the sample holding part, it is continuously generated from a substance made of beryllium or carbon due to the collision of an electron beam transmitted through the sample. X-rays can be reduced to one fifth or less, and the number of reflected electrons can be reduced.
Thereby, the sample observation apparatus which can observe with high resolution and high precision can be provided.
(10) The sample observation apparatus is characterized in that the light element member is thicker than the penetration depth of the electron beam. Thereby, since the electron beam which permeate | transmitted this sample is absorbed by this light element member, without permeate | transmitting this light element member, the sample observation apparatus which can observe with high resolution and high precision can be provided.
(11) The sample observation apparatus is characterized in that the light element member is grounded.
Thereby, since the light element member is not charged, a sample observation apparatus capable of observing with high resolution and high accuracy can be provided.
(12) An electron beam optical system including an electron source, a lens for focusing an electron beam, an electron beam scanning deflector, a sample stage on which a sample is placed, and the electron beam is emitted from the sample to be generated from the sample. In a sample observation apparatus equipped with a detector for detecting electrons and X-rays, a member (absorbing member) containing at least a light element material is installed behind the sample, and the electron beam is irradiated to observe the sample. It is set as the sample observation method characterized by having. As a result, it is possible to reduce the influence of backscattered electrons and X-rays that are generated when the electron beam that has passed through the sample is incident at a location other than the sample, and thus provides a sample observation method that enables observation and analysis with high accuracy and high sensitivity. it can.
(12) an ion source, a lens for focusing an ion beam, a focused ion beam optical system including an ion beam scanning deflector, an electron source, a lens for focusing an electron beam, and an electron beam optical system including an electron beam scanning deflector; In a sample observation apparatus including a sample stage on which a sample is placed, a function of separating a second sample from the sample using the focused ion beam, a manipulator for extracting the second sample, and an electron beam are provided. A detector that detects electrons and X-rays generated from the second sample by irradiating a minute sample is provided, and a member (absorbing member) containing at least a light element material is placed behind the extracted second sample Thus, a sample observation method is provided which has a function of observing the second sample with an electron beam. As a result, the extracted sample is not taken out to the atmosphere, and can be freely set with respect to the beam for observing the observation target surface of the extracted sample. Electrons transmitted through the sample collide with members other than the sample. Can reduce the effects of backscattered electrons and X-rays. For this reason, the sample observation method which can observe and analyze the internal cross section of a sample in high resolution and a short time can be provided. In particular, by applying it to semiconductor wafers, it can be used for semiconductor manufacturing process inspection, and contributes to the improvement of manufacturing yield by early detection of device defects and short-time quality control.

  According to the present invention, it is possible to realize a sample observation apparatus and a micro sample processing observation method capable of performing internal observation of LSI devices and the like that are increasingly miniaturized with high resolution and high quality in a short time. Further, by performing EDX analysis on a thin sample formed by thin film processing and performing high-precision elemental analysis, it is possible to provide a sample observation device with a comprehensive cross-section observation and analysis efficiency.

The configuration and operation of the sample observation apparatus according to the embodiment of the present invention will be described.
<Embodiment 1>
The apparatus configuration and operation of the first embodiment will be described with reference to FIGS. 1, 2, 3, 4, 5, and 6. FIG. 1 and 2 show the overall configuration of the apparatus, and FIG. 3 shows in detail the configuration around the focused ion beam optical system, scanning electron microscope optical system, and sample stage. In the present embodiment, a wafer handling apparatus is shown in the sample observation apparatus of the present invention. FIG. 3 shows a schematic overhead cross-section of FIG. 1, but there are some differences in the orientation and details of the device for convenience of explanation, but this is not an essential difference. In FIG. 1, a focused ion beam optical system 31 and an electron beam optical system 41 are appropriately installed above the vacuum sample chamber 60 at the center of the apparatus system. Inside the vacuum sample chamber 60, a sample stage 24 on which a wafer 21 to be a sample is placed is installed. The optical systems 31 and 41 of the two lens barrels are adjusted so that their central axes intersect at one point near the wafer 21 surface. The sample stage 24 incorporates a mechanism for moving the wafer 21 from front to back and from side to side with high accuracy, and is controlled so that a specified position on the wafer 21 is directly below the focused ion beam optical system 31. The sample stage 24 further has a function of rotating, up and down, or tilting. An exhaust device (not shown) is connected to the vacuum sample chamber 60 and is controlled to an appropriate pressure. The optical systems 31 and 41 are each provided with an exhaust system (not shown) and maintained at an appropriate pressure. The vacuum sample chamber 60 includes a wafer introduction unit 61 and a wafer transfer unit 62. A wafer transfer robot 82 and a cassette introducing means 81 are disposed adjacent to the vacuum sample chamber 60. An operation control unit 100 that controls and manages a series of processing of the entire apparatus including sample processing observation evaluation is arranged on the left side of the vacuum sample chamber 60.

  Next, the wafer introduction operation of this embodiment will be outlined. When the wafer cassette 23 is placed on the table of the cassette introduction means 81 and a work start command is issued from the operation control console 100, the wafer transfer robot 82 pulls out a wafer as a sample from a designated slot in the cassette, and FIG. The orientation adjusting means 83 shown adjusts the orientation of the wafer 21 to a predetermined position. Next, the wafer 21 is placed on the mounting table 63 when the hatch 64 above the wafer introducing means 61 is opened by the wafer transfer robot 82. When the hatch 64 is closed, a narrow space is formed around the wafer to form a load lock chamber. After evacuation by a vacuum evacuation means (not shown), the mounting table 63 is lowered. Next, the wafer transfer means 62 picks up the wafer 21 on the mounting table 63 and mounts it on the sample table 24 in the vacuum sample chamber 60. The sample stage 24 is provided with means for chucking the wafer 21 as necessary to correct warpage of the wafer 21 and to prevent vibration. Based on the input coordinate value information of the observation analysis position on the wafer 21, the operation control unit 100 moves the sample stage 24 to stop the observation analysis position of the wafer 21 just below the focused ion beam optical system 31.

  Next, the process of sample processing observation evaluation will be described with reference to FIG. In the sample observation apparatus of the present invention, the focused ion beam optical system 31 includes an ion source 1, a lens 2 that focuses the ion beam emitted from the ion source 1, an ion beam scanning deflector 3, and the like, and an electron beam optical system. Reference numeral 41 includes an electron gun 7, an electron lens 9 that focuses the electron beam 8 emitted from the electron gun 7, and an electron beam scanning deflector 10. In addition, the secondary particle detector 6 for detecting the secondary particles from the wafer by irradiating the wafer 21 with the focused ion beam (FIB) 4 or the electron beam 8, the movable sample stage 24 on which the wafer 21 is placed, desired The sample stage controller 25 for controlling the position of the sample stage in order to specify the position of the sample, and the probe 72 at the tip of the manipulator 70 are moved to the position for extracting the micro sample, and extracted, and the focused ion beam (FIB) 4 or the electron beam 8 And an X-ray detector 16 for detecting X-rays excited upon irradiation of the electron beam 8 and a manipulator control device 15 for controlling an optimum position and direction in observing and evaluating a specific position of the micro sample. And a deposition gas supply device 17 for fixing the micro sample to the probe 72, and a light element member insertion device 55 having a member 56 made of a light element material at the tip. The size of the light element member 56 is 5 mm long, 2 mm wide, and 2.5 mm thick. The light element member 56 has a hole 57 as shown in FIG. The hole diameter is 1mm and the depth is 2mm.

Next, in this embodiment, the process of sample processing observation evaluation after wafer introduction will be outlined.
First, in a state where the sample stage is lowered and the tip of the probe 72 is separated from the wafer 21, the probe 72 is moved in the horizontal direction (XY direction) with respect to the sample stage 24, and the tip of the probe 72 is set as the FIB4 scanning region. To do. The manipulator control device 15 retracts the probe 72 after storing the position coordinates.

  The FIB 4 is irradiated onto the wafer 21 from the focused ion beam optical system 31, and a groove is formed so as to draw a U-shape across the observation analysis position p2 as shown in FIG. The processing region has a length of about 5 μm, a width of about 1 μm, and a depth of about 3 μm, and is connected to the wafer 21 on one side surface. Thereafter, the sample stage 24 is tilted and processed so as to form a slope of a triangular prism with the FIB 4. However, in this state, the micro sample 22 and the wafer 21 are connected by the support portion S2. Next, after returning the inclination of the sample stage 24, the probe 72 at the tip of the manipulator 70 is brought into contact with the end of the micro sample 22 to the micro sample 22, and then the contact point 33 is reached by the deposition gas supply device 17 (FIG. 3). The deposited film is formed at the contact point 33 by irradiation of the FIB 4, and the probe 72 is joined and integrated with the micro sample 22. Next, the micro sample 22 is cut by cutting the support portion S2 with FIB4. The micro sample 22 is supported by the probe 72, and the preparation for taking out the surface and the internal cross section for the purpose of observation and analysis as the observation analysis surface p3 of the micro sample 22 is completed. In FIG. 4, reference numeral 71 denotes a probe holder that holds the probe 72 on the manipulator 70. Next, as shown in FIG. 5B, the manipulator 70 is operated to lift the micro sample 22 from the surface of the wafer 21 to an upper height. As shown in FIG. 5 (c), the observation cross-section p3 having a desired thickness is obtained by irradiating the micro sample 22 with the FIB 4 while being supported by the probe 72 as necessary, and appropriately performing additional processing. Form.

  Next, as shown in FIG. 6, the micro sample 22 is rotated, and the manipulator 70 is moved so that the electron beam 8 of the electron beam optical system 41 is incident on the observation cross section p3 substantially perpendicularly. It is made to rest after being controlled. Next, as shown in FIG. 6, the probe 72 at the tip of the light element member 56 manipulator 70 made of carbon and the sample table 24 are inserted into the space opposite to the surface on which the electron beam 8 is incident by the light element member insertion device 55. Move relative to the position between and insert. At this time, the sample is positioned near the center of the upper surface of the hole provided in the light element member. The micro sample 22 is installed so that the distance from the upper surface of the hole is about 0.1 mm.

  When the electron beam 8 is incident on the micro sample 22, secondary electrons 301 reflecting the internal structure and surface shape are generated from the surface of the micro sample 22, and an X-ray 401 including characteristic X-rays peculiar to the elemental composition of the incident portion is generated. appear. By detecting the X-ray 401 and analyzing the energy distribution, the elemental composition of the portion irradiated with the electron beam can be known (spot element analysis). Observation is performed by scanning the electron beam 8 in one direction or two-dimensional direction on the observation analysis surface of the micro sample 22 and detecting the secondary electrons and X-rays by the secondary electron detector 6 and the X-ray detector 16 respectively. Observe the shape of the analysis surface and the elemental composition distribution (element line analysis or mapping analysis).

  FIG. 8 is a diagram for explaining the effect of the light element member 56 in this embodiment. FIG. 8 (a) is a conventional observation method, and FIG. 8 (b) is a case of observing a micro sample in which no light element member is inserted. 8C and 8D show the case where the light element member 56 of the present invention is inserted.

  In the following description, the acceleration voltage of the electron beam 8 is 15 kV, the sample 21 is a silicon wafer, the main component of the sample 21 and the minute sample 22 is silicon, and the thickness of the minute sample 22 along the incident direction of the electron beam 8 is The case of 0.1 μm will be described. When the electron beam 8 is incident on the micro sample 22, about 95% of the electrons are transmitted through the micro sample 22. An example of the transmitted electrons is indicated by 201 in FIGS. 8B, 8C, and 8D. The spread angle of transmitted electrons is about 40 degrees in all angles. The transmitted electron 201 shown in the drawing represents an example, and not all the transmitted electrons pass through this orbit.

  When the light element member shown in FIG. 8B is not inserted, the electrons 201 transmitted through the micro sample 22 are incident on the silicon wafer 21 as the sample. The incident electrons 201 are scattered in the silicon wafer, and there are electrons 205 that jump out of the surface of the silicon wafer again. These electrons are called backscattered electrons. In this process, secondary electrons 303 and X-rays 403 are generated from the surface of the silicon wafer. About 20% of incident electrons are scattered backward at normal incidence (incidence angle 0 degree) and 40% at 60 degrees incidence. The back-scattered electrons 205 are incident on the micro sample 22 again, and secondary electrons 304 and X-rays 404 are generated at a location different from the incident point of the electron beam 8.

  Since the secondary electron detector 6 shown in FIG. 6 detects not only the measurement sample but also all the secondary electrons emitted from the vicinity thereof, the secondary electron detector 6 transmits in addition to the secondary electrons 301 generated on the surface of the micro sample. Secondary electrons 303 generated by electrons and secondary electrons 304 generated by backscattered electrons are also detected. In high-resolution observation, it is preferable that such secondary electrons are as few as possible. Next, X-ray detection will be described. FIG. 6 shows a general semiconductor X-ray detector 16. A collimator 162 having an inner surface along a part of a side surface of a cone formed by an irradiation point of the electron beam 8 on the minute sample and a detection surface of the X-ray detection element 161 is attached to the tip of the X-ray detector. However, X-rays generated in the space between the two dotted lines shown in the figure are also detected. Accordingly, the X-rays 403 and 404 generated other than the irradiation point of the electron beam 8 of the micro sample 22 shown in FIG. 8B are also detected. For this reason, not only the signal from the micro sample to be observed but also the signal from the silicon wafer, which is the introduced sample under the micro sample, is detected, and the electron beam is directly irradiated to the silicon wafer even in the actual measurement result. The X-ray spectrum is almost the same as the case. Moreover, the base material of both the micro sample and the introduced sample is silicon, and the characteristic X-rays of Si from the micro sample and the characteristic X-rays of Si from the introduced sample appear in the X-ray spectrum. Separation of both components was not possible. For this reason, with this configuration, it has been impossible to accurately measure the composition of a small sample element with high sensitivity.

  In the method of inserting the light element member 56 having a flat surface without a hole between the micro sample 22 and the sample 21 shown in FIG. 8C, the electrons transmitted through the micro sample 22 are light element members 56 made of carbon. Is incident on. A material made of carbon has a lower backscattering rate than a material made of silicon, which is about 6% at normal incidence (incidence angle 0 °) and 27% at 60 ° incidence compared to a silicon wafer as an introduction sample. As a result, the ratio of backscattering was less than 1/3.

  Characteristic X-rays 403 peculiar to carbon atoms are generated from the carbon member by the electrons 201 transmitted through the minute sample. Since the signal detected by the X-ray detection element is discriminated for each X-ray energy, it can be distinguished from the X-ray from the silicon of the minute sample. Further, since the number of electrons backscattered by the carbon member can be smaller than the number of electrons backscattered by the silicon wafer, the secondary electrons 304 and X-rays 404 generated by the backscattered electrons 205 returning to the micro sample 22 are also obtained. Less. However, continuous X-rays generated by bremsstrahlung generated by carbon members are continuous X-rays generated from silicon wafers and the integrated intensity is about 1/5, but continuous X in the energy region of 1 to 3 keV where the characteristic X-ray peak of Si appears. The line (background) intensity could hardly be reduced. For this reason, the sensitivity of elements that generate characteristic X-rays in this energy range could not be improved.

  In the method of inserting the light element member 56 having a hole between the micro sample 22 and the sample 21, which is a feature of the present invention shown in FIG. 8D, most of the electrons transmitted through the micro sample 22 are made of carbon. It enters the hole 57 of the light element member 56.

  When the transmitted electrons 201 collide with the side surface and bottom surface of the hole 57, the reflected electrons 403 or the X-rays 303 are generated as described above. Many of the reflected electrons are radiated in a direction in which the reflected electrons are reflected. Therefore, many of the reflected electrons are absorbed in the hole, and less of the reflected electrons come out of the hole. Therefore, the number of backscattered electrons re-entering the micro sample 22 is very small as compared with FIG. When a light element member made of carbon is irradiated with an electron beam with an acceleration voltage of 15 kV, the penetration depth of the electron beam is 2.6 μm. In this embodiment, since the thickness of the bottom of the hole is 0.2 mm, the electron beam does not penetrate the carbon member. Further, some of the X-rays 303 generated in the holes are absorbed by the side portion of the light source material portion 56, and the X-rays reaching the X-ray detector are reduced. For this reason, the detection of X-rays generated outside the observation target of the minute sample is reduced. The carbon member is grounded in order to prevent the carbon member from being charged. As a result, background noise is reduced, and elemental analysis with high accuracy and a high signal-to-noise ratio becomes possible. Therefore, it is possible to observe the minute sample 22 with high resolution and high accuracy.

  FIG. 25 is an X-ray spectrum showing the effect of the present invention. In order to clarify the effect, an Al plate was installed in place of the Si wafer, and a micro sample that was taken out of the Si wafer and thinned to 0.15 microns was used as the micro sample. This is a result obtained by accumulating X-rays generated by irradiating an electron beam with an acceleration voltage of 25 kV and a beam current of about 1 nA for 100 seconds.

  The curve shown by the dotted line is a spectrum corresponding to FIG. 8B, and four characteristic X-ray peaks are observed on the continuous X-ray signal. In addition to the characteristic X-ray peak attributed to Si, which is the base material of the micro sample, a large Al characteristic X-ray peak from the Al plate below the micro sample appears in the spectrum. In addition to these two peaks, characteristic X-ray peaks corresponding to oxygen and carbon elements appear. This is considered to reflect the oxide film of the micro sample and the Al plate and the hydrocarbon adhering to the surface. It is considered that the amount of continuous X-rays is larger than the ratio of the characteristic X-ray peak of Si and continuous X-rays in the case of Si alone, and the continuous X-rays from the Al plate overlap. In this way, in the configuration shown in FIG. 8 (b), the large Al characteristic X-ray peak from the underlying Al plate and the continuous X-ray overlap, and the signal-to-noise ratio of the characteristic X-ray peak from Si of the micro sample is deteriorated. I understand that. When the base is a Si wafer, the Si peak from the micro sample and the Si peak from the base overlap, making separation impossible.

  Next, a curved line L2 indicated by a thin solid line is a spectrum corresponding to FIG. 8C and is obtained when a carbon plate is inserted between a micro sample having Si as a base material and an Al plate. By inserting the carbon plate, it was observed that the Al peak from the Al plate was hardly observed, but the carbon peak was increased. This penetrates the micro sample, and the electrons colliding with the Al plate collide with the carbon plate, and the characteristic X-ray peak of carbon increases. As described above, it is understood that most of the electrons irradiated to the minute sample are transmitted through the minute sample under this experimental condition. On the other hand, the total amount of continuous X-ray signals is small, but the characteristic X-ray energy of Si is not significantly different from that before inserting the carbon plate. For this reason, the Si peak becomes an isolated peak, which makes it easy to discriminate, but the ratio to the continuous X-ray (signal-to-noise ratio) has not improved much.

  Next, a curve L3 indicated by a thick solid line is a spectrum corresponding to FIG. 8 (c), and is obtained when a carbon plate having holes is inserted between a micro sample having Si as a base material and an Al plate. The hole diameter was 1 mm and the depth was 2 mm. The hole did not penetrate and the thickness of the hole bottom was 0.5 mm. The sample was installed so that the center of the opening surface of the hole was approximately 0.1 mm below the minute sample. It was confirmed that the continuous X-ray decreased significantly and the characteristic X-ray of carbon also decreased. As a result, it was possible to detect the characteristic X-ray peak of Si with high sensitivity.

  FIG. 8 (a) shows the generation of secondary electrons when observing a thick sample rather than a micro sample such as the outermost surface of the wafer. The electron beam 8 incident on the outermost surface of the wafer is scattered inside the wafer and diffused into a region 211 having a radius of about 1 μm, part of which is absorbed in the wafer and part of it is backscattered. In the diffusion region, only secondary electrons generated between the outermost surface and a depth of several nm are generated from the surface and detected by the secondary particle detector. That is, the detected secondary electrons are the sum of the secondary electrons 301 from the irradiation point of the electron beam 8 and the secondary electrons 302 due to backscattered electrons. Since the X-ray has a strong penetrating power in the substance, the X-ray 402 generated in the diffusion region reaches the wafer surface. For this reason, the spatial resolution of elemental analysis by X-rays is several μm under the above measurement conditions. In addition, when trying to detect an element different from the element of the base material existing in the region of 1 μm or less, X-rays from the part spread to several μm are included, so the signal-to-noise ratio is reduced and high sensitivity Detection becomes difficult.

  On the other hand, in the present embodiment, since the thickness of the micro sample is thinned to about 0.1 μm, it diffuses only in the thickness of the micro sample of the electron beam 8 and backscatters in the micro sample. There are few electrons to play. Therefore, the specific gravity of secondary electrons generated at the irradiation point increases and high-resolution observation is possible. In addition, since the X-ray generation region is limited to the electron beam diffusion region, the spatial resolution of two-dimensional elemental analysis by X-ray detection can be dramatically improved to 0.1 μm.

  Furthermore, since the angle of the observation analysis plane p3 can be adjusted to a desired angle, the detection efficiency of secondary electrons by the secondary electron detector 6 is the same as that when observing the outermost surface of the wafer. The observation condition of the surface p3 becomes very good, the resolution reduction which is a problem in the conventional example can be avoided, and more detailed observation analysis can be performed. In addition, since the micro sample 22 is observed and analyzed while being left in the sample chamber in a vacuum atmosphere without being taken out of the apparatus, the internal cross section of the target sample can be high resolution without being contaminated by foreign air exposure or adhering foreign matter. High-precision observation and analysis at the optimum angle can be realized. Moreover, observation and analysis can be performed with a high processing capacity of 2 to 3 or more locations per hour.

  In this embodiment, an example in which a vertically processed hole is used has been described. However, the present invention can be applied to a hole having any shape as long as incident electrons are not re-emitted. Is self-explanatory.

  However, since the micro sample 22 suspended in the probe 72 is easily affected by vibration, the micro sample 22 is observed as shown in FIG. Is made to land on the light element member 56, the vibration of the minute sample can be greatly suppressed, and high-quality observation and analysis are possible.

  Although the observation of the cross section P3 in the silicon wafer has been described above, when observing a part P2 of the silicon surface, the observation analysis plane P2 may be scanned with the electron beam 8 as shown in FIG. In this case, the opposite side in the surface P2 direction is thinly formed. Conventionally, when a foreign substance is observed on the surface of the silicon wafer by secondary electron image observation by the method shown in FIG. 7A, the thickness of the foreign substance is thin when trying to examine the composition by X-ray observation. Therefore, it is buried in the X-ray signal from the silicon wafer substrate, and the composition analysis may not be possible. In the present embodiment, since a thin sample formed into a thin film is observed, the signal from the surface of the surface foreign matter is reduced, and the sensitivity to the composition of the surface foreign matter can be improved by an order of magnitude.

  Moreover, although the case where carbon is used as the material of the light element member has been described, beryllium or a composite of beryllium and carbon may be used. When beryllium is used, X-rays generated when electrons penetrating a minute sample collide with beryllium have energy inherent to beryllium, but are smaller than the energy range detectable by current X-ray detectors. There is an advantage that it does not appear in the spectrum. Further, when a composite of carbon and beryllium is used, the position of the light element member is adjusted, and an electron beam transmitted through the minute sample is incident on the carbon portion of the light element member and when incident on beryllium. By observing one spectrum, it is possible to analyze the generation factor of the carbon peak appearing in the spectrum, that is, whether it is from a small sample or from a light element member.

In this example, the hole formed in the light element member is a cylindrical hole. However, it is not essential that the hole is cylindrical, and it is essential that an electron beam transmitted through a micro sample enters the hole. The shape is not particularly limited.
Putting these together,
An electron source, a lens for focusing the electron beam, an electron beam optical system including an electron beam scanning deflector, a sample stage on which the sample is placed, and electrons and X generated from the sample by irradiating the sample with the electron beam In a sample observation apparatus having a detector for detecting a line, a sample observation method for observing the sample by irradiating the electron beam with a member (absorbing member) containing at least a light element material behind the sample is there. Also, an ion source, a lens for focusing an ion beam, a focused ion beam optical system including an ion beam scanning deflector, an electron source, a lens for focusing an electron beam, an electron beam optical system including an electron beam scanning deflector, and a sample In a sample observation apparatus including a sample stage on which a sample is placed, a function of separating a second sample from the sample using the focused ion beam, a manipulator for extracting the second sample, and an electron beam are combined with the minute sample. A detector for detecting electrons and X-rays generated from the second sample by irradiating the sample is provided, and a member (absorbing member) containing at least a light element material is placed behind the extracted second sample. There is also a sample observation method for observing the second sample with an electron beam.
<Embodiment 2>
A schematic configuration of a sample observation apparatus according to the second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the basic structure of the sample observation apparatus shown in FIG. 3 is replaced with a light element made of carbon embedded in the sample table 24 shown in FIG. 11 instead of the light element member provided at the tip of the second manipulator 55. The element member 56 is used. The sample stage 24 has a surface on which the sample 21 is mounted and a surface lower by about 5 mm than the surface, and a light element member 56 is installed on the lower surface. FIG. 22 is a detailed cross-sectional view of the main part including the light element member 56. The light element member 55 has a hole 57 in the center in the direction of irradiation with an electron beam for observing the micro sample 22. The diameter of the hole 57 is 1 mm and the depth is 2 mm. The light element member 57 has a portion raised in the direction of the X-ray detector 16, and a carbon plate 500 extending to the upper center portion of the hole 57 is fixed to the portion. The micro sample 22 extracted from the sample 21 by the focused ion beam and processed as necessary is moved to the entrance center of the hole 57 by the movement of the manipulator and the sample stage 24. The sample held by the probe 72 is in contact with the tip of the carbon plate 500 and observed. By touching, the influence of vibration of a minute sample at the time of observation can be reduced.

  The upper surface of the carbon plate 500 is disposed so as to coincide with the lower boundary line of the X-ray detection angle 409 limited by the collimator 162. For this reason, a part of the X-rays generated by the electron beam 8 passing through the micro sample 22 and being diffused and colliding with the inner surface of the hole 57 are absorbed by the thick light element member and the metal member on the outer periphery thereof. As a result, the observed X-ray spectrum has little background noise, and high-precision and high-sensitivity elemental analysis is possible.

Furthermore, in the present embodiment, the height of the position where the sample is installed and the position where the micro sample is moved to the light element member 56 and observed are different. For this reason, the distance (working distance) from the electron optical system 41 can be increased, and the electron beam can be narrowed down even with a high acceleration voltage. In this example, it is possible to observe with an acceleration voltage of 15 kV. This facilitates the detection of elements that cannot be distinguished because the X-ray peaks overlap when irradiated with an electron beam at a low acceleration voltage. In addition, since the electron beam with a high acceleration voltage has little scattering in the micro sample and does not diffuse, the element distribution of the micro sample can be observed with high spatial resolution.
In the present embodiment, an example in which one light element member 56 is provided is shown, but a plurality of light element members may be arranged around the sample 21. In this case, it is possible to start observation in a shorter time by moving the micro sample to the light element member closest to the portion of the sample 21 from which the micro sample has been extracted.

As described above, in this embodiment, the angle of observation analysis can be adjusted to a desired angle including vertical observation, it can be observed while placed in a sample chamber in a vacuum atmosphere, and a micro sample is fixed to a light element member. Therefore, the observation condition of the micro sample 22 is extremely high because it can avoid the vibration problem in the micro sample observation, obtain an X-ray spectrum with a small background noise, use an electron beam with a high acceleration voltage, and the like. To be good. As a result, it is possible to avoid a reduction in resolution, which has been a problem in the prior art, and to perform optimum and meticulous observation analysis quickly and efficiently. As a result, high quality observation analysis can be performed with high throughput.
<Embodiment 3>
A schematic configuration of a sample observation apparatus according to the third embodiment of the present invention will be described with reference to FIG. In this embodiment, instead of the second manipulator 55 having the light element member at the tip in the basic configuration of the sample observation apparatus shown in FIG. 3, the angles of the third sample stage 18 and the third sample stage And a second sample stage control device 19 for controlling the height and the like.
The process from the focused ion beam optical system 31 in this embodiment to irradiating the sample with the ion beam and extracting the minute sample from the wafer is the same as in the first embodiment. In this embodiment, instead of observing / analyzing the extracted micro sample while supported by a manipulator, the micro sample is fixed to a third sample stage for observation / analysis. FIG. 14 shows a state in which the micro sample 22 is fixed to the third sample stage 18. In this embodiment, a light element member 56 made of carbon is installed on the back surface of the small sample fixing portion of the third sample stage 18.
The bottom surface of the micro sample is brought into contact with the third sample stage 18 so that the observation surface of the micro sample 22 is opposite to the light element member 56, and the deposition gas is allowed to flow between the third sample stage 18 and the micro sample 22 by FIB 4. The micro sample 22 is fixed to the third sample stage 18 with the ion-assisted deposition film 75 deposited at the contact point. In order to prevent inconvenience of foreign matter adsorption to the surface of the observation cross section 21 or destruction of the surface of the observation cross section 21 when the micro sample 22 is formed or when the deposition gas is deposited, irradiation of the FIB 4 is performed. It is also possible to create a desired observation section 21 by irradiating the FIB 4 after appropriately setting the angle by the third sample stage operation so that the angle is parallel to the observation section of the micro sample. The electron beam is irradiated from the side opposite to the light element member 56 and the cross section is observed.
By installing the third sample stage shown in FIG. 15, it is possible to handle a plurality of micro samples collectively. The micro sample 22 is extracted from the wafer 21, fixed to an appropriate position on the third sample table 18 beside the sample table, and the operation of extracting the next micro sample 22 is repeated, whereby a plurality of wafers 21 are fixed to the sample table 24. Individual cross-section observation and elemental analysis are possible, and the distribution of the cross-sectional structure over the entire wafer 21 can be efficiently examined. In FIG. 15, several micro samples are arranged and fixed on the third sample stage 18, and the stop orientation of the sample stage 24 and the angle of the second sample stage 18 so that the micro sample 22 is at an appropriate angle with respect to the electron beam 8. If the sample observation / analysis is performed in a state in which both are adjusted, it is possible to repeatedly observe and analyze a plurality of micro samples continuously or while comparing them, so that the cross-sectional structure and element distribution over the entire wafer 21 are examined in detail and efficiently. be able to.

  As described above, the secondary electron detection efficiency similar to that in the case of observing the wafer surface can be obtained in this embodiment, the angle of observation analysis can be adjusted to a desired angle including vertical observation, vacuum The observation conditions of the micro sample 22 are such that it can be observed while being placed in the sample chamber in the atmosphere, and the problem of vibration in the micro sample observation can be avoided by separating the micro sample from the manipulator and fixing it to the second sample stage. It will be very good. As a result, it is possible to avoid a reduction in resolution, which has been a problem in the prior art, and to perform optimum and meticulous observation analysis quickly and efficiently. As a result, high quality observation analysis can be performed with high throughput.

In the present embodiment, the method and mode for observing the micro sample extracted with the first manipulator fixed to the third sample stage are shown, but in the state where the micro sample extracted is fixed to the first manipulator, It is obvious that the present invention can be applied even when the direction of the micro sample is appropriately adjusted and observed by the first manipulator (first holder) so that the third sample stage comes to the side. At this time, whether the minute sample is separated from or in contact with the second sample stage is not an essential problem and may be either.
<Embodiment 4>
A schematic configuration of a sample observation apparatus according to the fourth embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the third sample shown in FIG. 17 is used in place of the light element member provided at the tip of the second manipulator (second holder) 55 in the basic configuration of the sample observation apparatus shown in FIG. A table 58 is used. The third sample stage 58 includes a light element member 56 made of carbon, and is attached to the tip of the second manipulator 55 via a sample stage holding rod 59. The sample table holding bar is designed with a material and dimensions that do not cause the sample table 58 to vibrate.

The process from the focused ion beam optical system 31 in this embodiment to irradiating the sample with the ion beam and extracting the minute sample from the wafer is the same as in the first embodiment. In this embodiment, instead of observing and analyzing the extracted micro sample in a state supported by a manipulator, the micro sample is fixed to the third sample stage 58 for observation and analysis. FIG. 17 shows a state in which the micro sample 22 is fixed to the third sample stage 58. In this embodiment, a light element member 56 made of carbon is installed on the back surface of the small sample fixing portion of the second sample stage 18. The bottom surface of the micro sample is brought into contact with the third sample stage 58 so that the observation surface of the micro sample 22 is opposite to the light element member 56, and the deposition gas is allowed to flow between the second sample stage 58 and the micro sample 22 using FIB 4. The micro sample 22 is fixed to the third sample stage 58 with the ion-assisted deposition film 75 deposited at the contact point. In order to prevent inconvenience of foreign matter adsorption to the surface of the observation cross section 21 or destruction of the surface of the observation cross section 21 when the micro sample 22 is formed or when the deposition gas is deposited, irradiation of the FIB 4 is performed. It is also possible to create the desired observation section 21 by irradiating the FIB 4 after setting the angle appropriately by operating the third sample stage so that the angle is parallel to the observation section of the minute sample. The electron beam is irradiated from the side opposite to the light element member 56 and the cross section is observed.
As described in the third embodiment, a plurality of minute samples can also be handled together in this embodiment. The micro sample 22 is extracted from the wafer 21, fixed to an appropriate position on the second sample table 58 beside the sample table, and the operation of extracting the next micro sample 22 is repeated, whereby a plurality of wafers 21 are fixed to the sample table 24. Individual cross-section observation and elemental analysis are possible, and the distribution of the cross-sectional structure over the entire wafer 21 can be efficiently examined.

As described above, the secondary electron detection efficiency similar to that in the case of observing the wafer surface can be obtained in this embodiment, the angle of observation analysis can be adjusted to a desired angle including vertical observation, vacuum The micro sample 22 can be observed while being placed in the sample chamber of the atmosphere, and the micro sample can be avoided by detaching it from the manipulator for extracting the micro sample and fixing the micro sample to the third sample stage. The observation conditions are very good. As a result, it is possible to avoid a reduction in resolution, which has been a problem in the prior art, and to perform optimum and meticulous observation analysis quickly and efficiently.
As a result, high quality observation analysis can be performed with high throughput.
<Embodiment 5>
A schematic configuration of a sample observation apparatus according to the fifth embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which the present invention is applied to the in-lens scanning electron microscope described in the section of the prior art, and FIG. 18 is a detailed view around the objective lens of the electron microscope. The in-lens system here refers to a scanning electron microscope apparatus that measures by placing a sample stage and a sample placed on the sample stage in an objective lens.

  As shown in FIG. 18, in this embodiment, the thin film sample 22 placed on the sample stage 706 is inserted and observed in a space between the magnetic poles 707 and 708 of the objective lens arranged above and below. The thin film sample 22 is a thin film processed by the method described in the first embodiment in the FIB processing apparatus so as to include a desired observation region, or a sample thinned by conventional mechanical polishing or ion milling, or The powder is fixed to a hydrocarbon-based thin film. The thin film sample 22 is fixed to a semicircular support 26 called a mesh.

  Under the thin film sample 22, a carbon member 56 having a hole having one of the features of the present invention and having a cylindrical outer shape with a collar is installed. The hole diameter is 1 mm, the depth is 1.5 mm, and the hole bottom thickness is 0.5 mm. An X-ray detection element 161 is disposed on the upper right side of the thin film sample 22. The thin film sample 22 is subjected to elemental analysis by detecting the X-ray 401 generated by scanning the thin film sample 22 with the electron beam 8 by the X-ray detection element 161.

  The carbon plate 501 is placed on the lower surface of the magnetic pole 707 to reduce the reflected electrons and X-rays generated by the collision of the reflected electrons 205 that are generated by irradiating the thin film sample 22 with the electron beam 8 toward the upper side of the sample. Yes. The periphery of the carbon member 56 is surrounded by a heavy metal material 503 made of tungsten. As a result, X-rays penetrating the carbon member are attenuated. Also, a carbon material fixture 504 for fixing the thin film sample 22 to the carbon member 56 so as to cover the mesh 26 adhering to the thin film sample 22 is installed on the X-ray detector side above the carbon member 56. Yes. The fixture 504 is well known as a shape that swells outward so as to contact a cone connecting the periphery of the detection portion of the X-ray detection element and the electron beam irradiation point of the thin film sample 22. As a result, X-rays generated by collision of scattered electrons near the entrance of the hole of the carbon member 56 are absorbed as much as possible, and are prevented from entering the X-ray detection element. Further, the electron beam 8 is not a complete linear beam but has a slight spread. When the electrons in the skirt collide with the mesh, X-rays peculiar to elements such as Ni, which is a typical material of the mesh, are generated, thereby hindering accurate elemental analysis of the thin film sample. In this embodiment, the upper side of the mesh is covered with a carbon material so that the characteristic X-rays of the elements constituting the mesh are not generated. In accordance with these effects, electrons that pass through the thin film sample 22 enter the hole of the carbon member 56, so that the background X-rays detected by the X-ray detection element and the effects described in the first embodiment are The reflected electrons that re-impact on the thin film sample 22 can be reduced. Since the thickness of the hole bottom of the carbon member 56 is 0.5 mm, the electron beam is absorbed without being transmitted even at an acceleration voltage of 50 kV. Therefore, in this embodiment, the lower magnetic pole 708 is not provided with a carbon plate.

Also in this embodiment, since background X-ray noise and reflected electrons re-collision with the thin film sample can be greatly reduced, a highly accurate and sensitive sample observation apparatus can be realized.
<Embodiment 6>
A schematic configuration of a sample observation apparatus according to the sixth embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which the present invention is applied to a scanning transmission electron microscope, and FIG. 19 is a detailed view of the periphery of the objective lens of the scanning transmission electron microscope. The structure is the same as that of the in-lens scanning electron microscope described in the fifth embodiment. In the case of a transmission electron microscope, the main function is to analyze the structure such as the atomic arrangement of a sample by observing a diffracted electron beam image of an electron beam that passes through the sample and has the same traveling method as the incident electron beam. It is.

Below the thin film sample 22 is one of the features of the present invention. A sample stage 706 is provided between the upper magnetic pole 707 and the lower magnetic pole 708 for the thin film sample. A mesh 26 is attached to the sample stage 706, and a sample is attached thereto. When X-rays generated when the electron beam passes through the sample are scattered and irradiated on the sample stage and its surroundings, and further X-rays are generated and enter the detection element 161, the detection signal is the same as in the previous embodiment. Cause the background to be raised. In order to prevent this, the sample stage 706 is structured to cover the X-ray with a light element member. Specifically, the inner wall of the sample stage having an opening for allowing the electron beam that has passed through the sample to enter a camera unit (not shown) provided under the lower objective 708 is covered with a light element. I will do it. A structure in which the light element member is fastened to the sample stage with a screw or a structure in which the light element member is fixed by welding can be considered. For example, the cylindrical sample holding portion of the sample stage may have an inner diameter of 1 mm and a length of 3 to 5 mm and a thickness of 0.5 mm. An X-ray detection element 161 is disposed on the upper right side of the thin film sample 22.
The thin film sample 22 is subjected to elemental analysis by detecting the X-ray 401 generated by scanning the thin film sample 22 with the electron beam 8 by the X-ray detection element 161.

  The structure of the sample stage 706 is the same as that described in the fifth embodiment except that the hole of the carbon member 56 penetrates. Since the hole of the carbon member 56 penetrates, some of the electrons that have passed through the sample collide with the magnetic pole 708 on the lower side of the objective lens, so the upper surface of the magnetic pole 708 is covered with the carbon plate 502.

Also in this embodiment, since background X-ray noise and reflected electrons re-collision with the thin film sample can be greatly reduced, a highly accurate and sensitive sample observation apparatus can be realized.
<Embodiment 7>
A schematic configuration of a sample observation apparatus according to the seventh embodiment of the present invention will be described with reference to FIG. The present embodiment is an example in which the present invention is applied to a general-purpose scanning electron microscope, and FIG. 20 is a detailed view around the objective lens of the general-purpose scanning electron microscope. The objective lens of the electron microscope in this embodiment has a structure having a magnetic pole 707 only on the upper side of the sample. A space below the magnetic pole 707 is wide open, and a sample is placed on a large sample stage 801 for measurement.

  Generally, in this type of electron microscope, reflected electrons are generated in a direction, so a reflected electron remover 802 made of a pair of permanent magnets is installed between the X-ray detection element 161 and the sample, and the reflected electrons are converted into X-rays. The light does not enter the detection element 161. The principle of the backscattered electron remover is based on the phenomenon that the backscattered electrons are bent by the magnetic field created between the magnets by installing a pair of permanent magnets across the space stretched between the sample observation point and the detection surface of the X-ray detector. Is. Although not clearly shown in the X-ray detectors of the first to fourth embodiments, a backscattered electron remover is housed inside the collimator.

  Also in this embodiment, a carbon member 56 having a hole, which is a feature of the present invention, is installed immediately below the thin film sample 22.

  Also in this embodiment, since background X-ray noise and reflected electrons re-collision with the thin film sample can be greatly reduced, a highly accurate and sensitive sample observation apparatus can be realized.

  In the above embodiment, an example in which a member obtained by processing a light element material is used as a light element member. However, a member processed with a metal or the like may be applied with a light element material. In this case, it is necessary that the light element material to be applied has a thickness that does not allow the electron beam to pass therethrough.

  To summarize the above embodiments, the first invention relates to an electron source, a lens for focusing an electron beam, an electron beam optical system including an electron beam scanning deflector, a sample stage on which a sample is placed, and the electron In a sample observation apparatus provided with either or both of an electron beam detector for irradiating a beam to the sample and detecting electrons generated from the sample and an X-ray detector for detecting X-rays, a light element is provided behind the sample. A sample observation apparatus using an electron beam having a function of observing the sample by irradiating the electron beam by installing a member (absorbing member) including a material and having a hole on a sample stage.

  The second invention is an ion source, a lens for focusing an ion beam, a focused ion beam optical system including an ion beam scanning deflector, an electron source, a lens for focusing an electron beam, and an electron including an electron beam scanning deflector. In a sample observation apparatus including a beam optical system and a sample stage on which a sample is placed, a function of separating a second sample from the sample using the focused ion beam, and a manipulator for extracting the second sample And an electron beam detector for detecting electrons generated from the sample by irradiating the minute sample with the electron beam and an X-ray detector for detecting X-rays, or both, and the extracted second A member (absorbing member) containing a light element material and having a hole behind the sample is placed between the sample stage or the sample stage and the second sample, and the second sample is turned into an electron. The ability to observe with a beam There is also the point to.

Furthermore, in the second invention, the manipulator for extracting the second sample includes a manipulator control device that drives the manipulator independently from the sample stage, and the second sample is supported by the manipulator. And there is also a function to change the irradiation angle of the charged particle beam for observation to the second sample. Further, the means for disposing the absorbing member of the second invention is a space behind the second sample extracted by the manipulator according to claim 3, that is, the observation by a second manipulator having an absorbing member at the tip. In this method, an absorbing member is inserted in the opposite space to the device that generates the charged particle beam. In addition, the second sample of the second invention is placed, and the second sample stage having an absorbing member made of a light element material is provided on the sample stage according to claim 2.
Furthermore, the second sample of the second invention is placed and driven independently of the sample stage according to claim 2, and the irradiation position and angle of the observation charged beam to the minute sample can be varied, The third sample stage is provided with the light element member according to claim 1.

  The absorbing member is covered with a heavy element material, and the absorbing member is at least carbon, beryllium, or a composite of carbon and beryllium and grounded so that the thickness is larger than the penetration depth of the electron beam. There is.

The whole apparatus block diagram in 1st embodiment of this invention. The top view by the whole apparatus structure in 1st embodiment of this invention. The apparatus detailed block diagram in 1st embodiment of this invention. The figure which shows the example of the micro sample processing method of this invention. The figure which shows the example of the micro sample observation method of this invention. The detailed block diagram in 1st embodiment of this invention. The principal part detail figure in 3rd embodiment of this invention. Schematic explaining the principle of the present invention. Schematic which shows another application in 1st embodiment of this invention. Schematic which shows another application in 1st embodiment of this invention. The principal part detail figure in 2nd embodiment of this invention. The principal part expanded sectional view in 2nd embodiment of this invention. The figure which shows the whole apparatus structure in 3rd embodiment of this invention. The principal part detail figure in 3rd embodiment of this invention. The principal part detail figure in 3rd embodiment of this invention. The figure which shows the whole apparatus structure in 4th Embodiment of this invention. The principal part detail figure in the 4th Embodiment of this invention. The principal part detail figure in the 5th Embodiment of this invention. The principal part detail figure in the 6th Embodiment of this invention. The principal part detail figure in the 7th Embodiment of this invention. The schematic block diagram of the conventional apparatus. The figure which shows the conventional processing method. The figure which shows the conventional observation method. The detailed block diagram of the conventional apparatus. The X-ray spectrum figure which shows the effect of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ion source, 2 ... Lens, 3 ... Ion beam scanning deflector, 4 ... Focused ion beam (FIB),
5 ... Central control display device, 6 ... Secondary electron detector, 7 ... Electron gun, 8 ... Electron beam, 9 ... Electron lens,
DESCRIPTION OF SYMBOLS 10 ... Electron beam scanning deflector, 14 ... Manipulator, 15 ... Manipulator control apparatus,
DESCRIPTION OF SYMBOLS 16 ... X-ray detector, 17 ... Deposition gas supply apparatus, 18 ... 3rd sample stand, 19 ... 2nd sample stand control apparatus, 21 ... Wafer, 22 ... Micro sample, 23 ... Cassette, 24 ... Sample stand, 25 ... Sample stage control device, 31 ... focused ion beam optical system, 32 ... focused ion beam optical system (# 2), 41 ... electron beam optical system, 51 ... analysis device, 55 ... light element member insertion device, 56 ... light element member , 57 ... hole, 58 ... third sample stand, 59 ... holding rod, 60 ... vacuum sample chamber, 61 ... wafer introduction means, 62 ... wafer transfer means, 63 ... mounting table, 64 ... hatch,
70 ... Manipulator, 71 ... Probe holder, 72 ... Probe, 75 ... Assist deposit film,
77 ... Sample collection tray, 81 ... Cassette introduction means, 82 ... Wafer transfer robot, 83 ... Orientation adjustment means, 90 ... Gas introduction pipe, 100 ... Operation control unit, 101 ... Sample, 105 ... Depositionable gas, 107 ... Square hole , 108 ... bottom hole, 109 ... groove, 110 ... gas nozzle 161 ... X-ray detection element, 162 ... collimator, 201-203 ... transmitted electrons, 205-207 ... backscattered (reflected) electrons, 301-304 ... secondary Electron, 401-408 ... X-ray, 409 ... X-ray detection angle, 500-504 ... Carbon plate, 706 ... Sample stand, 802 ... Reflected electron remover p1 ... Observation location, p2 ... Observation analysis plane, p3 ... Observation analysis plane , S1 ... internal cross section, s2 ... support part.

Claims (10)

  An electron source, a lens that focuses the electron beam, a deflector that scans the electron beam, an objective lens that irradiates the sample with the electron beam, a sample stage on which the sample is placed, and an electron beam that irradiates the sample piece X-ray detector including an X-ray detector for detecting X-rays generated from the sample piece, a first holder for holding the sample piece, and a light element material provided between the sample stage and the first holder A sample observation apparatus using an electron beam, comprising: a shielding member made of a member for reducing the shielding property; and a second cage for holding the shielding member.   A sample stage comprising an electron source, a lens for focusing the electron beam, a deflector for scanning the electron beam, an objective lens for irradiating the sample with the electron beam, and a member partially containing a light element material and reducing X-rays A holder for holding the sample piece, and an X-ray for detecting an X-ray generated from the sample piece by contacting the sample piece attached to the holder with a part of the sample stage and irradiating the sample piece with an electron beam And a sample observation device using an electron beam.   An electron source, a lens for focusing the electron beam, a deflector for scanning the electron beam, an objective lens for irradiating the sample with the electron beam, a first sample stage on which the sample is placed, and the first sample stage A second sample stage provided above, a shielding member made of a member that contains a light element material and reduces X-rays, and a part of the second sample stage, and is placed on the second sample stage And an X-ray detector that detects X-rays generated from the sample by irradiating the sample with an electron beam, and a sample observation apparatus using an electron beam.   The sample observation apparatus using an electron beam according to claim 1, wherein the shielding member has an opening.   An electron source, a lens for focusing the electron beam, a deflector for scanning the electron beam, an objective lens for irradiating the sample with the electron beam, a sample stage on which the sample is placed, and a sample by irradiating the sample with the electron beam An X-ray detector for detecting X-rays generated from the sample; and a holder for holding a sample made of a member having a cylindrical shape and an inner wall containing a light element material and reducing X-rays on the sample stage. A sample observation device using an electron beam.   The sample observation apparatus using an electron beam according to claim 5, wherein the cage is disposed inside the objective lens.   A focused ion beam optical system including an ion source, a lens for focusing an ion beam, a deflector for scanning an ion beam, an electron source, a lens for focusing an electron beam, an electron beam optical system including a deflector for scanning an electron beam, and a sample A sample stage, a manipulator for separating the sample piece from the sample using a focused ion beam, and extracting the sample piece, and irradiating the sample piece with the electron beam to detect X-rays generated from the sample piece A sample observation apparatus using an electron beam, characterized by having an X-ray detector to perform, an absorbing member including a light element material behind the extracted sample piece, and a function of observing the sample piece with an electron beam .   An electron source, a step of focusing the electron beam, a step of deflecting the electron beam, a step of placing the sample on the sample stage, a step of irradiating the sample with the electron beam, and irradiating the sample with the electron beam Detecting the X-rays generated from the sample, holding the sample piece for removing the sample piece from the sample on the sample stage, separating the sample piece from the sample stage, and the holding step A step of relatively moving the sample piece held at a predetermined position, and a step of setting a shielding member made of a member containing a light element material and reducing X-rays between the sample stage and the holder. The sample observation method using the electron beam characterized by having.   A step of focusing the ion beam from the ion source, a step of fixing a holder to the sample for separation from the sample on the sample stage with the focused ion beam, and attaching a sample piece separated to the holder A step of moving relative to a position, a step of arranging a shielding member made of a member containing a light element material and reducing X-rays between the sample stage and the holder, and focusing an electron beam from an electron source An electron beam comprising: a step of deflecting an electron beam on the sample piece; and a step of irradiating the sample piece with the electron beam to detect X-rays generated from the sample. Sample observation method.   A step of placing the sample on a sample stage including a concave, light element material and including a shielding region for reducing X-rays, a step of focusing an ion beam from an ion source, and a focused ion beam on the sample stage Fixing the holder to the sample in order to separate the sample piece from the sample; attaching the sample piece separated to the holder; and moving the sample piece relative to the shielding area of the sample stage; and A step of focusing the electron beam, a step of irradiating the sample with the electron beam and deflecting the sample, and a step of detecting the X-ray generated from the sample by irradiating the sample with the electron beam. Sample observation method using electron beam.

Images