JP5001741B2 - Sample stage and sample analysis method - Google Patents

Description

  The present invention relates to a sample stage and a sample analysis method using the stage. In particular, the present invention relates to a sample stage suitable for observing a sample to be deformed by pulling the sample with a scanning electron microscope (SEM) or the like.

  When observing a sample to which a tensile stress is applied with a scanning microscope or the like, a sample stage for pulling the sample is used. As this stage, there is one that pulls a sample in the horizontal direction (Patent Document 1 as a similar technique). Normally, such a stage applies a tensile stress to the sample by fixing one end of the sample and pulling the other end. When observation is performed by heating the sample to a predetermined temperature, the sample is heated by bringing a heater into contact with a portion of the sample that does not deform with tension.

JP 2001-76662 A paragraph 0003

  However, in the conventional sample stage, one of the sample end portions is a fixed end and the other is a movable end, and the center position of the deformation shifts with tension. For this reason, it is difficult to observe a fixed point such as the center of tension.

  Further, when heating the sample, if the heater is brought into contact with a portion that is deformed as it is pulled and heated, the heater may interfere with deformation of the sample. For this reason, in order to heat the heater in contact with the sample, the heater must be brought into contact with a location away from the deformed location. As a result, it is unclear whether the deformed part can be accurately controlled to the actual target temperature. On the other hand, a non-contact heater cannot be expected to transfer heat by conduction, and convection cannot be expected in a vacuum vessel. Therefore, there is no means to transfer heat to the sample only by radiation, and the sample can be heated efficiently and accurately. difficult.

  In addition, tungsten or the like is used for the heater. However, in the vacuum vessel, the components of the heater evaporate during heating, and the evaporated component may contaminate the sample surface, preventing proper observation.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a sample stage and a sample analysis method capable of reliably observing and analyzing a deformed portion of a sample.

  Another object of the present invention is to provide a sample stage and a sample analysis method capable of heating a deformed portion of a sample to an accurate temperature.

  Still another object of the present invention is to provide a sample stage and a sample analysis method capable of appropriately performing analysis and observation without contamination of the sample.

  The sample stage of the present invention is a sample stage for holding a sample to be analyzed in a vacuum vessel. The stage includes a pair of holding portions that hold both ends of the sample, and a drive mechanism that applies a tensile force to the sample by driving the holding portions in directions away from each other.

  According to this configuration, each of the holding portions that hold both ends of the sample is driven in a direction away from each other, so that the center of the deformed portion accompanying the tension does not substantially move, and the center of the deformed portion is easily moved. It is possible to observe a fixed point.

  As one form of the sample stage of the present invention, a main heater that is disposed so as to expose the sample analysis surface and heats the vicinity of the sample analysis surface so as to allow deformation of the sample accompanying the drive of the drive mechanism. Preparation.

  According to this configuration, since the analysis surface to be observed in the SEM or the like is not shielded by the heater, it is possible to heat the sample to a predetermined temperature and observe the deformation state accompanying the tension at the heating temperature. it can. Moreover, since the main heater does not hinder the deformation of the sample, a smooth pulling operation can be performed.

  As one form of the sample stage of the present invention, the main heater may be disposed so as to face a surface other than the analysis surface of the sample and be in non-contact with the sample.

  According to this configuration, since the main heater is not in contact with the sample, the heater does not hinder the deformation of the sample.

  One form of the sample stage of the present invention is that the main heater is covered with a coating material that does not evaporate at the heating temperature.

  According to this configuration, since the constituent material of the main heater does not evaporate at the heating temperature of the heater, it is possible to avoid the evaporation component from contaminating the sample and hindering analysis and observation.

  One embodiment of the sample stage of the present invention includes a sub-heater that interlocks with each holding portion and that heats a sample portion in which the sample does not substantially deform.

  According to this configuration, by providing the sub heater in addition to the main heater, it is possible to accurately heat a portion where the sample is deformed to a desired temperature. In particular, the sub-heater heats the sample portion where the deformation of the sample does not substantially occur, and therefore does not hinder the deformation of the sample.

  As one form of the sample stage of the present invention, the sub heater is in contact with a sample.

  According to this configuration, since the sub-heater is a contact type, the sample can be efficiently heated. In particular, since the sub-heater is brought into contact with a sample portion where the deformation of the sample does not substantially occur, it does not hinder the deformation of the sample.

  One form of the sample stage of the present invention is that the sub-heater is covered with a coating material that does not evaporate at the heating temperature.

  According to this configuration, since the constituent material of the sub-heater does not evaporate at the heating temperature of the heater, it is possible to avoid the evaporation component from contaminating the sample and hindering analysis and observation.

  As one form of the sample stage of the present invention, the driving mechanism includes a single driving source and a power transmission mechanism that transmits a driving force from the driving source to both holding units.

  According to this configuration, by using a single drive source, both the holding portions can be driven away from each other while saving space and weight.

  As one form of the sample stage of the present invention, the drive mechanism may include a drive source that drives each holding unit independently.

  According to this configuration, by making the driving source independent for each holding unit, it is possible to drive one holding unit without synchronizing with the other holding unit. Therefore, not only can both ends of the sample be pulled, but also the same function as a conventional stage in which one end side of the sample is a fixed end and the other end side is a movable end can be provided.

  As one form of the sample stage of the present invention, each holding unit is configured to be detachable from the drive mechanism.

  According to this structure, since each holding | maintenance part is detachable with respect to a drive mechanism, a holding | maintenance part can be replaced | exchanged according to the form of a sample.

  On the other hand, the sample analysis method of the present invention is a sample analysis method in which a sample held on a sample stage in a vacuum vessel is deformed and analyzed, and both ends of the sample are pulled by the sample stage and accompanied by tension. The analysis is performed by deforming the sample so that the center position of the sample deformation region does not substantially move.

  According to this configuration, since the center position of the sample deformation region accompanying the tension is held so as not to move substantially, the center position can be easily observed at a fixed point.

  One form of the sample analysis method of the present invention is to make the movement amount of each end of the sample the same.

  If the movement amount of each end portion of the sample is the same, it is possible to easily prevent the center position of the sample deformation region accompanying the tension from moving substantially.

  One embodiment of the sample analysis method of the present invention is to perform analysis by heating the sample while allowing deformation of the sample accompanying tension.

  According to this configuration, the sample can be heated to a predetermined temperature and the deformation state at that temperature can be analyzed and observed without hindering deformation of the sample accompanying tension.

  One form of the sample analysis method of the present invention is to measure the sample temperature by fixing a temperature detection means in the vicinity of the sample deformation region.

  If it is in the vicinity of the sample deformation region, the temperature of the sample deformation region, which is the analysis location, can be measured as accurately as possible.

  As one form of the sample analysis method of the present invention, the sample stage is disposed so as to face a surface other than the sample analysis surface and be in non-contact with the sample, and to heat the vicinity of the sample analysis surface. It is preferable to perform tension by arranging a heat conductive flexible member between the main heater and the sample.

  According to this configuration, the heat of the main heater can be efficiently transmitted to the sample by conduction due to the presence of the flexible member. Further, the flexible member can be deformed following the deformation of the sample and does not hinder the deformation of the sample.

  One embodiment of the sample analysis method of the present invention is to perform analysis in a state where driving of the sample stage is stopped.

  According to this configuration, a clear analysis result (analysis image) can be obtained in an environment with little vibration in a state where the deformation of the sample is temporarily stopped.

  According to the sample stage of the present invention and the sample analysis method of the present invention, the center of the deformed portion due to tension does not substantially move, and the center of the deformed portion can be easily observed at a fixed point.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. Here, an example is described in which a tensile test is performed on a magnesium alloy sample, and a deformation evaluation due to the tensile evaluation is performed on an EBSD (Electron Back Scatter Diffraction Pattern) using SEM. .

[Sample stage]
<Overall configuration>
As shown in FIGS. 1 and 2, the sample stage is arranged in a vacuum vessel of the SEM, and holds the holding units 1L and 1R that hold the sample S (FIG. 3) and the drive that drives the holding units 1L and 1R. A mechanism 2, a main heater 3 for heating the sample S, and sub heaters 4L and 4R are provided. The drive mechanism 2 drives the holding portions 1L and 1R and applies a tensile load to the sample S to deform it. The sample S is scanned with an electron beam through the SEM objective lens 200, the inelastic backscattered electrons from the sample S are detected by the EBSD detector 300, and the change of the Kikuchi pattern created by the scattered electrons is analyzed. Thus, a distribution image of the crystal orientation of the polycrystalline sample is obtained.

<Holding part>
The holding units 1L and 1R are metal blocks that hold each end of the sample S. Each of the pair of holding portions 1L and 1R is driven by a drive mechanism 2 described below so as to be close to and away from each other on the same axis. In EBSD, it is necessary to tilt the sample with respect to the incident electrons. For this reason, in this example, the holding portions 1L and 1R are inclined and attached to the sliders 23L and 23R of the drive mechanism so that the analysis surface (front surface) of the sample S is inclined at 70 ° with respect to the horizontal.

  As shown in FIG. 3, the holding portions 1L and 1R have a fitting recess 11 into which a large portion S1 formed at the end of the sample S is fitted. The fitting recess 11 is composed of a T-shaped hole 11A formed substantially at the center of the surface of the holding part, and a slit 11B connected to the hole 11A and reaching the side surface of the holding part. FIG. 3 shows a state in which the covers (not shown) of the holding portions 1L and 1R are removed. At the time of the test, a cover that covers the sample end is screwed to the surface of the holding portions 1L and 1R, and the sample S Is prevented from falling off from the fitting recess 11.

  The holding parts 1L and 1R are configured to be detachable from the sliders 23L and 23R. If various types of specimens are prepared according to the shape of the sample S, the holding parts 1L and 1R can be changed by changing the holding parts 1L and 1R. A simple sample can be held. In this example, the holding portions 1L and 1R that only fit the end portion of the sample S into the fitting recess 11 are used. However, the end portion of the sample S may be gripped like a chuck.

<Drive mechanism>
The drive mechanism 2 is a mechanism that drives the holding portions 1L and 1R in a direction away from each other, and includes a motor 21, a rotation shaft 22, and a pair of sliders 23L and 23R that are drive sources. In this example, a single motor 21 is used to rotate the rotating shaft 22, and the sliders 23L and 23R are moved closer to and away from each other with the rotation. In this example, the rotational force of the motor 21 is transmitted to the rotary shaft 22 via the reduction gear of the gear box 24. The rotary shaft 21 has one end supported by the gear box 24 and the other end supported by the side wall 25 of the stage, and is provided with male threads formed in opposite directions toward the end of the shaft. The sliders 23L and 23R made of a metal block are screwed into the male screws. Therefore, if the rotating shaft 22 is rotated by driving the motor 21, the sliders 23L and 23R are driven so as to approach and separate, and the holding portions 1L and 1R attached integrally with the sliders 23L and 23R also approach and separate. Driven. In this example, the case where the sample S is subjected to a tensile test is taken as an example. However, if the driving mechanism 2 is used, the sample S can be compressed via the holding portions 1L and 1R.

<Main heater>
A main heater 3 is provided at a substantially intermediate position between the holding portions 1L and 1R (sliders 23L and 23R) (see FIGS. 1 and 3). The main heater 3 is fixed, for example, fixed to the bottom surface of a stage (not shown). The main heater 3 includes a heater body and a heating block 3A, and heats the central portion in the longitudinal direction of the sample, that is, the central portion where deformation occurs due to tension. More specifically, the heating block 3A having a concave section is used, and the sample S is fitted into the concave portion during analysis. However, the heating block 3A is arranged so as to surround the back and top and bottom surfaces of the sample S in a non-contact manner, and the analysis surface (front surface) of the sample S is open. By opening this analysis surface, the sample S can be scanned with an electron beam.

  In this example, a ceramic heater is used for the heater body. In the ceramic heater, the heat source is covered with ceramic such as alumina or silicon nitride. Therefore, even under vacuum, the constituent material of the heat source does not evaporate, and the ceramic itself does not evaporate, so the evaporating material does not contaminate the sample.

  Such temperature control of the main heater 3 includes manual control and PID control. Manual control is performed by adjusting the amount of voltage to the main heater 3 with a volume (not shown) while observing the temperature of a thermocouple (not shown) displayed on a controller (not shown). In PID control, using a control computer (not shown), the current supply to the heater 3 is automatically adjusted to a specified temperature. These temperature control methods are the same for the sub-heaters 4L and 4R described below.

<Sub heater>
Further, a pair of sub-heaters 4L and 4R are provided on both sides of the main heater 3. The sub-heaters 4L and 4R suppress the heat dissipation of the sample S heated by the main heater 3 through the large portions S1 at both ends. The sub-heaters 4L and 4R also include a heater body and a heating block. The material and basic configuration of the heater body of the sub-heaters 4L and 4R and the material of the heating block are the same as those of the main heater 3. However, unlike the main heater 3, this heating block is brought into contact with the sample. In particular, in this example, the heating block is covered with a metal cover (not shown) so that almost the entire circumference of the sample S can be in contact with the metal to increase the heating efficiency. Since the sub-heaters 4L and 4R are brought into contact with the sample S, they are in contact with both sides of the main heater 3 and where the sample S is not substantially deformed by driving the holding portions 1L and 1R. In this way, the sub-heaters 4L and 4R are brought into contact with the sample S, but as the sample S is pulled, the distance between the sub-heaters 4L and 4R and the center portion where the deformation of the sample S occurs, that is, The heat conduction distance changes. Therefore, by combining both the main heater 3 and the sub heaters 4L and 4R, it is possible to more accurately control the temperature of the central portion where the sample S is deformed.

  The sub-heaters 4L and 4R are driven in conjunction with the slider. By linking the sub heaters 4L and 4R to the sliders 23L and 23R, the sub heaters 4L and 4R can follow the extension of the sample S and continue to be heated. The sub-heaters 4L and 4R and the slider are preferably connected to each other with a small cross-sectional area so as to minimize heat dissipation through the sliders 23L and 23R.

  The sub-heaters 4L and 4R can perform manual control and PID control in the same manner as the main heater 3. The temperature control of the sub heaters 4L and 4R can be performed independently of the main heater 3, and the temperature of the individual sub heaters 4L and 4R can also be controlled independently.

<Other configuration requirements>
The stage of the present invention includes a strain gauge. In this example, the strain gauge 5 (see FIG. 1) is assembled to one holding portion 1L. With this strain gauge 5, the tensile load is measured.

  The motor 21 of the drive mechanism performs servo control when pulling the sample S. However, when the motor 21 is stopped (slider driving is stopped) while a predetermined tensile load is applied to the sample S during analysis, the servo control of the motor 21 is switched to constant current control. When the motor 21 is stopped in a state where a certain amount of stress is applied, the motor 21 tries to maintain a predetermined counter value by the servo mechanism, and a phenomenon in which the counter value reciprocates between fine values appears. This phenomenon slightly changes the current of the motor 21 and causes vibration. Therefore, if constant current control is used, image vibration due to vibration of the motor 21 can be suppressed, and a more accurate image can be acquired. In addition, the displacement amounts of the sliders 23L and 23R (holding portions 1L and 1R) are converted from the number of rotations of the motor 21.

[Sample analysis method and operation of each part]
To analyze a sample using the above stages, the following procedure is used.

  First, a sample S is prepared. In this example, a sample S was obtained by cutting a magnesium alloy of AZ31 into a predetermined shape by wire cutting and then polishing the surface. This sample S has a large portion S1 at both ends, a medium width portion S2 inside, a small width portion S3 and a minimum width portion S4 in steps (see FIG. 3), and the length is about 40 mm. It is. With this shape, when the sample S is pulled left and right, plastic deformation due to elongation occurs substantially at the center of the minimum width portion S4, and the deformation region can be substantially limited to only the minimum width portion S4.

  Next, a thermocouple is set on the sample S. In this example, a thermocouple 6 (chromel-alumel) is welded to a region adjacent to the location heated by the main heater 3 in the sample S, that is, a location located approximately between the main heater 3 and the sub-heater 4L (Fig. 4). Since the welded portion is a portion where the elongation of the sample S does not substantially occur, it is possible to prevent the deformation of the sample S from being inhibited and to prevent the thermocouple 6 from falling off. On the other hand, since this welding location is adjacent to the deformation region of the sample S, it can be considered that the temperature of the deformation region of the sample S is substantially measured. The measurement temperature at this point is defined as the end temperature of the sample. In this example, in order to confirm the temperature of the deformation region of the actual sample, a thermocouple is also welded to the central portion of the minimum width portion S4 in the sample for the purpose of temperature measurement only, so that the center temperature of the sample is obtained. Measurements were made.

  Next, the sample S is set in the holding units 1L and 1R. At that time, the large portion S1 is fitted into the T-shaped hole 11A of the holding portion, the middle width portion S2 is fitted into the slit 11B, and a part of the middle width portion S2, the small width portion S3, and the minimum width portion S4 are the holding portions 1L and 1R. It is assumed to protrude from By this setting, the minimum width portion S4 is opposed to the main heater 3, and the small width portion S3 is brought into contact with the sub-heaters 4L and 4R. Then, the large portion S1 and the middle width portion S2 are covered with a cover so that the sample S does not fall off the holding portions 1L and 1R.

  Furthermore, when setting the sample S to the holding portions 1L and 1R, Cu wool W was interposed between the main heater 3 and the sample S (see FIG. 4). Cu wool W is excellent in thermal conductivity, and by contacting both the main heater 3 and the sample S, it functions as a heat conduction path from the main heater 3 to the sample S, and increases the heating efficiency of the sample S. In addition, if Cu wool W is used, even if the portion heated by the main heater 3 is deformed, the deformation can be followed and the deformation of the sample S is not hindered. Cu wool W can be made of other materials and forms as long as it is a heat conductive flexible member. The material is preferably metal or ceramic with high thermal conductivity, and the form is preferably filament or powder.

  Once the sample S is set, set the main and sub heaters 3, 4L, 4R to the prescribed temperature, drive the motor 21, move the holding parts 1L, 1R away from each other, and apply tension to the sample . With this tension, the sample S expands. At that time, since both ends of the sample S are evenly pulled, the center of the deformation region is substantially not moved, and the fixed point analysis can be performed in a state where the center is captured in the field of view.

  At the time of analysis, the driving of the sliders 23L and 23R is temporarily stopped. In this state, the SEM is used to scan the analysis surface of the sample S with an electron beam, and inelastic backscattered electrons from the sample S are detected by an EBSD detector to obtain a distribution image of the crystal orientation of the polycrystalline sample. At the time of this analysis, the motor 21 is controlled at a constant current, so that image disturbance due to vibration of the motor 21 can be suppressed.

  Of course, the load-displacement curve can be obtained by recording the relationship between the load applied by the strain gauge 5 and the displacement amount of the holding portions 1L and 1R.

A specification example of the present invention stage is shown below.
Stroke of holding part (difference between shortest distance and longest distance of holding part): 3mm
Maximum tensile load: 400MPa
Tensile speed: 0.3-10μm / sec
Heating temperature: 300-350 ° C at sample temperature
Heating rate: ~ 8 ℃ / sec

  As a result of measuring the target temperature of the deformation region of the sample in this embodiment at 200 ° C., when the main heater temperature is 300 ° C. and the sub heater temperature is 200 ° C., the center temperature of the sample is 199 ° C. and the end of the sample The temperature was 199 ° C., and it was found that the deformation region of the sample could be heated substantially to the target temperature. Further, the obtained image was clear without the influence of contaminants. For comparison, the same heating was performed without Cu wool. The gap between the main heater and the sample is 0.5 mm. As a result, in order to heat the sample to almost the target temperature, it was necessary to control the temperature of the main heater to about 600 ° C. when the temperature of the sub heater was 200 ° C.

  In addition, this invention is not limited to said embodiment, A various change can be made. For example, it is possible to use two motors, drive independent rotating shafts with each motor, and move a slider (a holding portion integrated with the slider) close to and away from each rotating shaft. In that case, since each slider (holding part) can be driven independently of each other, it is possible not only to pull both ends of the sample but also to perform a test in which one end of the sample is fixed and only the other end is pulled. In addition, by changing the form of the holding part, one holding part holds one end of the sample in a direction perpendicular to the driving direction of the slider, and the other holding part applies stress to the other end side of the sample, Analysis and observation can also be performed by bending or shearing the sample.

  The stage and the analysis method of the present invention can be suitably used for various devices that perform analysis and observation in a vacuum vessel, such as an SEM, an X-ray photoelectron spectrometer, an Auger electron spectrometer, and the like. In particular, it can be used for accurately analyzing and observing changes in a sample accompanying tension of a metal material such as magnesium.

It is a schematic plan view which shows embodiment of the stage of this invention. FIG. 2 is an XX schematic arrow view of FIG. 1. It is a model front view which shows the holding | maintenance state of the sample in embodiment of this invention stage. It is an enlarged view which shows the arrangement | positioning relationship between the main heater and sample in FIG.

Explanation of symbols

1L, 1R holder
11 Fitting recess 11A T-shaped hole 11B Slit
2 Drive mechanism
21 Motor 22 Rotating shaft 23L, 23R Slider 24 Gearbox 25 Side wall
3 Main heater 3A Heating block
4L, 4R Sub-heater
5 Strain gauge 6 Thermocouple
200 Objective 300 EBSD detector
S Sample S1 Large part S2 Medium width part S3 Small width part S4 Minimum width part
W Cu wool

Claims (16)

A sample stage for holding a sample to be analyzed in a vacuum vessel,
A pair of holding parts for holding both ends of the sample;
A drive mechanism that applies tensile force to the sample by driving the holding portions in directions away from each other ;
A main heater that is disposed so as to expose the analysis surface of the sample, and that heats the vicinity of the analysis surface of the sample so as to allow deformation of the sample accompanying driving of the drive mechanism;
A sample stage comprising: a sub-heater that interlocks with each holding portion and that heats a sample portion in which the sample is not substantially deformed . 2. The sample stage according to claim 1 , wherein the main heater is opposed to a surface other than the analysis surface of the sample and is disposed in non-contact with the sample. The main heater, a sample stage according to claim 1 or 2, characterized by being covered with the covering material does not evaporate at that heating temperature. The sub-heater, the sample stage according to any one of claims 1 to 3, characterized in that formed by contact with the sample. Sub-heater, the sample stage according to any one of claims 1 to 4, characterized in that covered by the covering material does not evaporate at that heating temperature. The drive mechanism includes a single drive source, according to any one of claims 1 to 5, characterized in that it comprises a power transmission mechanism for transmitting the driving force from the driving source to the two holding portions Sample stage. The drive mechanism, the sample stage according to any one of claims 1 to 5, characterized in that it comprises a drive source for driving each holder independently. Specimen stage according to any one of claims 1 to 7, the holding unit is characterized by being configured detachably to the drive mechanism. A method for analyzing a sample in which a sample held on a sample stage in a vacuum vessel is deformed and analyzed,
The sample stage is opposed to a surface other than the analysis surface of the sample and is disposed in non-contact with the sample, and includes a main heater that heats the vicinity of the analysis surface of the sample,
A heat conductive flexible member is arranged between the main heater and the sample, and both ends of the sample are pulled by the sample stage, so that the center position of the sample deformation region accompanying the tension is not substantially moved. A method for analyzing a sample, characterized in that the analysis is performed by deforming the sample. 10. The sample analysis method according to claim 9 , wherein the movement amount of each end of the sample is the same. Method for analyzing a sample according to claim 9 or 10, characterized in that for making an analysis of a sample was heated while allowing deformation of the sample due to the tensile. Method for analyzing a sample according to any one of claims 9 to 11, characterized in that to measure the sample temperature by fixing the temperature sensing means in the vicinity of the sample deformation region. The sample stage includes a sub-heater for heating a sample portion in which deformation of the sample does not substantially occur,
  13. The sample analysis method according to claim 9, wherein the sample is heated by the main heater and the sub heater.   The sample analysis method according to claim 9, wherein the flexible member is a filament or a powder. 15. The sample analysis method according to any one of claims 9 to 14 , wherein the analysis is performed in a state where driving of the sample stage for pulling both ends of the sample is temporarily stopped.   16. The sample analysis method according to claim 15, wherein the sample stage is set to constant current control while driving of the sample stage is stopped.

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