JP2003194746A - Information acquiring device and device and method for evaluating sample - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample evaluating device that can analyze the cross-sectional structure of a sample in a state where the temperature of the sample is adjusted. <P>SOLUTION: This sample evaluating device has a heat insulating section 2 which maintains the temperature of a fixed sample 1 at a preset value, an ion beam generating section 4 which projects an ion beam upon the sample 1, and an electron beam generating section 5 which projects an electron beam upon the sample 1. This device also has an electron detector 6 which detects secondary electrons emitted from the sample 1 when the ion beam or electron beam is projected upon the sample 1; and a control section 7 which brings the cross section of the sample 1 by causing the ion beam generating section 4 to project the ion beam upon a prescribed part of the sample 1 and, at the same time, scans the surface of the prescribed part or the cross section with the ion beam or electron beam, and acquires a mapped image based on secondary electrons emitted from a plurality of points and detected by means of the electron detector 6 synchronously to the scanning. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an information acquisition device for acquiring information on a sample. More specifically, the present invention relates to a sample evaluation apparatus and a sample evaluation method for evaluating a sample whose state and morphology change due to temperature changes.

[0002]

2. Description of the Related Art Demand for cross-sectional evaluation of organic materials such as ecosystems and plastics and processing of fine structures is increasing with the increase in functional devices. As a main cross-section manufacturing method used to obtain information on the organic substance structure, a cutting method with a blade, a resin embedding method, a freezing embedding method, a freezing cleaving method, an ion etching method, etc. are known. When observing the internal structure of organic matter with an optical microscope,
Usually, a method of embedding an organic substance in a resin and then cutting with a microtome is adopted.

However, since the optical microscope is limited to macroscopic observation of a cross section, and the cut-out position cannot be specified, in order to observe and analyze the structure at the specified position, it is necessary to repeat the cross-section manufacturing work. It took a lot of effort.

Therefore, recently, a scanning electron microscope (SE
A FIB-SEM apparatus has been developed in which a processing function of a focused ion beam (FIB) apparatus is added to an M: Scanning Electron Microscope (FIB) apparatus. FI
The apparatus B is an apparatus that focuses an ion beam from an ion source into a thin beam, irradiates the processed sample, and performs processing by etching or the like. This FIB etching technology is becoming quite popular, and is widely used especially for structural analysis of semiconductors, defect analysis, and transmission electron microscope sample preparation. The FIB-SEM apparatus can perform the step of etching the sample by the FIB apparatus and the step of observing the cross section of the sample by the SEM apparatus with a single device. The cutting position is designated and designated. It is possible to observe and analyze the structure of the position.

As the above-mentioned FIB-SEM device, various structures have been proposed so far. For example, in Patent Document 1, the processing depth during FIB processing is observed with a SEM while the sample is fixed, and the surface of the sample being processed is SIM.
(Scanning Ion Microscope) A device that allows observation is proposed. This apparatus has a structure in which the FIB from the FIB generation unit and the electron beam from the electron beam generation unit are irradiated to the same location of a fixed sample at different angles. By alternately performing SEM observation (or SIM observation) performed by detecting secondary electrons emitted from the sample in response to beam (or FIB) irradiation, monitor the processing state while processing the sample can do.

In addition to the above, Patent Document 2 proposes a method in which the electrode is irradiated with a beam to prevent charge-up of a sample during FIB processing, thereby enabling highly accurate processing.

[0007]

[Patent Document 1] Japanese Unexamined Patent Publication No. 1-181529

[Patent Document 2] Japanese Unexamined Patent Publication No. 9-274883

[0008]

However, when observing and analyzing the cross-sectional structure of a sample, such as an organic substance, whose state and morphology change with temperature, using the above-mentioned conventional FIB-SEM apparatus, FIB processing is required. The temperature of the sample changes due to the heat generated therein, which changes the state and morphology of the sample, and the cross-sectional structure of the sample cannot be accurately analyzed.

An object of the present invention is to solve the above-mentioned problems and to provide an information acquisition device capable of acquiring the information of the surface for which information is desired to be acquired while adjusting the temperature of the sample.

A further object of the present invention is to solve the above problems and to provide a sample evaluation apparatus and a sample evaluation method capable of analyzing a cross-sectional structure while adjusting the temperature of a sample.

Another object of the present invention is to solve the above problems, to process a sample while adjusting the temperature of the sample, and to accurately obtain information on the processed part. An object is to provide an apparatus and a sample evaluation method.

[0012]

In order to achieve the above object, an information acquiring apparatus according to the present invention comprises a mounting table on which a sample is mounted, and a temperature adjusting means for adjusting the temperature of the sample. And an exposure unit for exposing a surface of the sample from which information is desired to be acquired, and an information acquisition unit for acquiring information about the surface exposed by the exposure unit.

A sample evaluation apparatus according to the present invention comprises a mounting table for mounting a sample, temperature adjusting means for adjusting the temperature of the sample, and ion beam generation for irradiating the sample with an ion beam. Means, electron beam generation means for irradiating the sample with an electron beam, and detection means for detecting an emission signal emitted from a predetermined portion of the sample in response to the irradiation of the ion beam or the irradiation of the electron beam. It is characterized by having. In this case, the predetermined part of the sample may be a part whose cross section is cut out by the ion beam or a part processed by the ion beam.

Further, in the above-described sample evaluation apparatus, a predetermined portion of the sample is irradiated with the ion beam to cut out a cross section, and the surface of the predetermined portion or the cut cross section is cut by the ion beam or the electron beam. Control means for scanning and acquiring image information about the surface of the predetermined portion or the cut-out section based on emission signals from a plurality of points detected by the detecting means in synchronization with the scanning. You may also have.

The sample evaluation method according to the present invention comprises: a first step of adjusting the temperature of the sample; a second step of irradiating a predetermined portion of the sample with an ion beam to cut out or process a cross section; Scanning an electron beam on a sectioned or processed section, and obtaining an image of the sectioned or processed section from an emission signal emitted from a plurality of points in synchronization with the scanning. And 3 steps.

In the present invention as described above, since the temperature of the sample is constantly adjusted, the temperature of the sample is kept at a desired temperature even during FIB processing, for example. Therefore, there is no change in the state or morphology of the sample as in the conventional case.

In the present invention, the cut-out or processed surface of the cross section means the surface viewed from one surface inside the sample, and the processed surface when the sample is processed (including deposition and etching). It also includes the surface that can be observed from a later point of view.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic configuration diagram of a scanning electron microscope for observing a cross section, which is a first embodiment of a sample evaluation apparatus of the present invention. This electron microscope is provided with a sample 1 that is fixed and a heat retaining unit 2 that keeps the temperature of the fixed sample 1 at a set temperature. The heat retaining section 2 can be housed in the sample chamber 3.

The sample chamber 3 is provided with an ion beam generator 4 for irradiating the sample 1 fixed to the heat-retaining portion 2 with an ion beam and an electron beam generator 5 for irradiating an electron beam. An electron detector 6 for detecting secondary electrons emitted from the sample 1 by irradiation with a beam or an ion beam is provided. The inside of the sample chamber 3 is evacuated by a pump (not shown) so that a predetermined low pressure can be maintained, whereby irradiation with an ion beam or an electron beam is possible. The pressure in the sample chamber 3 is 10 ^-10
It is preferable that it is not less than Pa and not more than 10 ^-2 Pa.

The ion beam generator 4 is used as an exposing means for irradiating the sample 1 with an ion beam to expose the surface of the sample to be exposed, for example, for cutting out a cross section.
Furthermore, it can also be used for SIM observation. In the case of SIM observation, the ion beam generator 4 and the electron detector 6 serve as information acquisition means, and secondary electrons generated when the sample 1 is irradiated with the ion beam are detected by the electron detector 6, and the electron detection is performed. Visualization is performed based on the detection signal from the device 6.

The electron beam generator 5 is used for SEM observation. In the case of SEM observation, the electron beam generator 4 and the electron detector 6 serve as information acquisition means, and the sample 1
Secondary electrons that are generated when the electron beam is irradiated to the electron detector 6 are detected by the electron detector 6, and are visualized based on the detection signal from the electron detector 6.

The detection signal from the electronic detector 6 is supplied to a control unit 7 which is a control means for acquiring image information, and the above-mentioned visualization during SIM observation and SEM observation is performed by this. It is performed by the control unit 7. For example, the control unit 7 obtains video information (mapping information) from the detection signal from the electronic detector 6, and displays the obtained video information on a display device (not shown) to perform visualization. In addition, the control unit 7 controls the generation of an ion beam in the ion beam generation unit 4 and the generation of an electron beam in the electron beam generation unit 5, and controls the irradiation and scanning of the ion beam and the electron beam on the sample 1. To go. The scanning of the beam can be controlled on the beam side, the stage side on which the sample is fixed, or both of them, but it is desirable to control on the beam side in consideration of the scanning speed and the like. Further, the irradiation positions of the ion beam and the electron beam can be controlled so as to coincide with each other on the sample 1.

The configurations of the electron beam generator 5, the ion beam generator 4, etc. are the same as those of the above-mentioned Patent Document 1 and Japanese Patent Laid-Open No. 11-26030.
The configuration described in Japanese Patent Publication No. 7 or the like may be used.

(Structure of Temperature Adjusting Means) The temperature adjusting means in this embodiment is provided with a heat retaining section 2 capable of adjusting the temperature of the sample. The heat retaining unit 2 is, for example, a sample stage with a temperature controller. FIG. 2 shows a schematic configuration of the sample stage with the temperature controller.

Referring to FIG. 2, the sample stage with a temperature controller has a sample stage 8 having a temperature varying mechanism 10 in a portion where the sample 1 is fixed, a thermometer 9a for directly detecting the temperature of the sample 1, and a temperature varying device. A thermometer 9b that is attached to a part of the mechanism 10 and detects the temperature in the vicinity of the sample 1 fixed to the temperature varying mechanism 10, and the temperature in the temperature varying mechanism 10 based on the temperature detected by the thermometer 9b. Temperature controller 7 for adjusting and maintaining the sample 1 at a preset temperature
a.

Although not shown in FIG. 2, a display unit for displaying the temperature detected by the thermometer 9a is provided, and the operator can confirm the temperature of the sample 1 from the temperature displayed on this display unit. can do. The temperature control unit 7a can also be configured to adjust the temperature in the temperature variable mechanism 10 based on the temperatures detected by both the thermometers 9a and 9b. Moreover, it becomes possible to control the temperature of the sample 1.

The temperature varying mechanism 10 is unitized together with the thermometer 9b, and a unit capable of controlling a necessary temperature range according to the set temperature can be incorporated in the sample stage 8. Examples of such a unit include a high temperature unit having a heating mechanism such as a heater and a low temperature unit having a cooling mechanism. If necessary, it is also possible to use a unit having a temperature varying function from both the low temperature side near the room temperature to the high temperature side.

The sample stage 8 can mechanically move, rotate, or incline the fixed sample 1 vertically and horizontally, thereby moving the sample 1 to a desired evaluation position. The movement control of the sample 1 on the sample stage 8 is performed by the control unit 7 described above.

As the above cooling mechanism, a cooling mechanism such as a Peltier element or a helium refrigerator can be used. In addition to the above, the cooling mechanism is a system in which a refrigerant pipe for flowing a refrigerant is provided on the side of the heat retaining portion facing the portion where the sample is fixed, and liquid nitrogen, water or other coolant is brought into thermal contact with the heat retaining portion. You may use.

Further, in order to increase the efficiency of absorbing heat generated during processing, it is preferable to devise a method for increasing the contact efficiency between the sample and the cooling section (heat retaining section). Such a device is, for example, configured to wrap the sample, and to create a sample holder that does not block the optical system of the device used during processing and observation, or to mount the sample on the mounting table. It is possible to realize it by processing it into a shape according to the above and holding it while keeping the maximum contact area.

Further, the non-processed region of the sample may be covered with a cooling member. In this case, the cooling member needs to be coated so as not to block the beam system.

(Cross Section Evaluation Method of Sample) The cross section evaluation method according to the present invention will be described below.

FIG. 3 is a flow chart showing a procedure for evaluating the cross section of the sample using the scanning electron microscope for observing the cross section shown in FIG. Hereinafter, the procedure of cross-section evaluation will be described with reference to FIG. 3, and the control for the SEM observation and the SIM observation by the control unit 7 according to the procedure and the temperature control of the sample by the temperature control unit 7a will also be specifically described. explain.

First, the sample 1 is fixed at a predetermined position (temperature varying mechanism 10) on the sample stage 8 (step S10),
After introducing this into the sample chamber 3, the evaluation temperature is set (step S11). When the evaluation temperature is set, the temperature of the temperature varying mechanism 10 is controlled by the temperature control unit 7a and the temperature of the sample 1 is maintained at the set evaluation temperature.
The temperature of the sample 1 at this time is detected by the thermometer 9a, and the operator can confirm whether or not the sample 1 is kept at the evaluation temperature from the detected temperature displayed on the display unit (not shown). it can.

In the present embodiment, it is preferable to process the sample while cooling it from room temperature. Further, it is more preferable to cool to a temperature of 0 ° C. or less, because if the sample contains water, it can be solidified.

When the cooling process as described above is adopted,
First, cool the sample to a predetermined temperature below room temperature, hold the cooled sample in a reduced pressure atmosphere, and irradiate a convergent beam while absorbing the heat generated near the irradiation surface of the sample. It is good to process while holding.

When the sample is cooled, it may be cooled rapidly from room temperature. In this case, the cooling rate is 40 ℃
It is preferable to cool at a speed of not less than / min. Thus, for example, when it is desired to measure the cross-sectional shape of a mixture whose dispersibility changes with temperature, the cross-section in a rapidly cooled state can be observed.

The cooling step is preferably performed before the depressurization step. This makes it possible to suppress the evaporation of the sample due to the reduced pressure. When the sample is composed of a substance having a small amount of evaporation, cooling may be performed simultaneously with depressurization.

The cooling step differs depending on the target sample, but in the case of general organic substances such as PET, 0 ° C.
It is preferable to cool in a temperature range of to -200 ° C, preferably -50 ° C to -100 ° C.

When the processing time and the cooling time are too long during low temperature cooling, residual gas in the sample chamber or substances generated during processing are adsorbed to the low temperature sample, which makes desired processing and observation difficult. There is. For this reason, it is preferable to provide a trap means for adsorbing residual gas or a substance generated during processing, and perform the processing and obtain information while cooling the trap means.

The present invention can be suitably applied to the case where the target sample is an organic substance, particularly a protein, a substance vulnerable to heat such as other biological substances, or a composition containing water. In particular, a composition containing water is more preferable because it can be processed while holding the water in the sample.

Further, since the irradiation of the focused ion beam is carried out in a reduced pressure atmosphere, when processing a composition containing water or an organic molecule having high volatility with the focused ion beam,
Moisture may evaporate due to heat generated during processing. Because of this, the effect of providing the temperature adjusting means as in the present invention is great.

In order to perform more accurate processing and structure evaluation, it is also preferable to include a step of extracting a suitable holding temperature during processing in advance. In this case, using a sample equivalent to the sample to be processed as a reference, processing is performed at a plurality of set temperatures, and it is preferable to determine the preferable holding temperature after investigating the relationship between the damage of the processed part and the cooling temperature.

In addition, in the case of a general FIB processing apparatus, it is often the case that after processing, the apparatus is moved to another apparatus such as an SEM apparatus to perform other work such as observation. In this case, the observation means with the temperature adjusted. Was difficult to move to. In the present embodiment, it is possible to provide a suitable processing apparatus in which the sample can be processed and observed in a cooled state, and there is no concern about the effect of the processed surface due to the attachment of water droplets or the like to the sample surface during cooling.

After confirming that the sample 1 was kept at the evaluation temperature,
While constantly checking the temperature of sample 1, SE of the surface of sample 1
M observation is performed (step S12). In this SEM observation, the control unit 7 controls the irradiation of the electron beam by the electron beam generation unit 5 and the movement of the sample stage 8, so that the sample 1 is scanned with the electron beam from the electron beam generation unit 5. Further, in synchronization with this scanning, secondary electrons are detected by the electron detector 6, and the control unit 7 displays an SEM image on a display unit (not shown) based on the detection signal of the secondary electrons. Thereby, the operator can perform SEM observation of the surface of the sample 1.

Next, the cross-section evaluation position is accurately determined from the image obtained by SEM observation of the surface of the sample 1 (SEM image displayed on the display section) (step S13).
The determined cross-section evaluation position is further observed by SIM (step S14). In this SIM observation, the irradiation of the ion beam by the ion beam generator 4 and the movement of the sample stage 8 are controlled by the controller 7, whereby the sample 1 is covered by the ion beam from the ion beam generator 5 in the range of the cross-section evaluation position. Scanned at. Further, in synchronization with this scanning, secondary electrons are detected by the electron detector 6, and the control unit 7
Displays a SIM image on a display unit (not shown) based on the detection signal of the secondary electrons. As a result, the operator can observe the surface SIM at the cross-section evaluation position determined in step S14.

Next, the FIB processing conditions are set (step S15). In this FIB processing condition setting, the cutout region and the cutout position are determined on the SIM image obtained by the surface SIM observation in step S14, and the cross-section processing conditions such as the acceleration voltage, the beam current, and the beam diameter are set. The cross-section processing conditions include rough processing conditions and finish processing conditions, which are set at this point. The rough processing conditions are
The beam diameter and energy amount are larger than those of the finishing conditions. Note that the cutout region and the cutout position can be determined on the SEM image obtained in step S14, but in consideration of the accuracy problem, on the SIM image on which the ion beam to be actually processed is used. It is more preferable to do in.

When the FIB processing conditions are set, first, F
IB processing (rough processing) is performed (step S16). In this rough processing, the control unit 7 controls the ion beam generator 4 under the rough processing conditions set above, and further controls the movement of the sample stage 8, so that the cutting region and the cutting position determined in step S15 are controlled. Is irradiated with an amount of ion beam necessary for cutting.

After the rough processing, the surface of the sample 1 is observed by SIM,
It is confirmed whether or not the image obtained by the SIM observation (SIM image) is processed up to near a desired position (step S17). Furthermore, the cross section produced by rough processing is SEM
Observe and confirm the state (roughness) of the cross section (step S1)
8). If the processing has not been performed up to the desired position, steps S16 and S17 described above are repeated. Even when the processed cross section is extremely rough, the above step S1
6 and S17 are repeated, in which case an operation such as gradually reducing the amount of the ion beam is added. The control of the surface SIM observation in step S17 is the same as that in step S12 described above. The control of the cross-section SEM observation in step S18 is basically the same as the case of step S12 described above except that the sample stage 8 is moved and controlled so that the processed cross section is irradiated with the electron beam. is there. The angle of incidence of the electron beam on the cross section at this time may be any angle as long as an SEM image can be obtained.

If it is confirmed that the rough machining has been performed up to the desired position, then the FIB machining (finishing) is carried out (step S19). In this finishing process, the control unit 7 controls the ion beam generating unit 4 under the finishing process conditions set above, and further controls the movement of the sample stage 8 to finish the rough-processed portion in step S16. The necessary amount of ion beam is irradiated. By this finishing process, it is possible to produce a smooth cross section that enables observation at high magnification using, for example, a scanning electron microscope.

Finally, Sample 1 produced as described above
SEM observation of the cross section is performed (step S20). The control at the time of this cross-section SEM observation is the same as the control in step S18.

As described above, in the cross-section observing scanning electron microscope of the present embodiment, the temperature of the sample 1 to be evaluated can be kept at the set value at all times, so that the state and morphology of the sample 1 change during FIB processing. Never. Therefore, accurate microstructure evaluation can be performed.

The temperature of the sample is preferably the same as the temperature set during the processing by the ion beam and the temperature set during the observation, but the temperature during the processing becomes lower than the temperature during the observation. May be set as follows. In this case, there may be a temperature difference of 10 ° C to 50 ° C between the processing step and the observation step.

(Embodiment 2) FIG. 4 is a schematic configuration diagram of a scanning electron microscope for observing a cross section, which is a second embodiment of the sample evaluation apparatus of the present invention. This electron microscope has substantially the same configuration as that of the above-described first embodiment except that an X-ray detector 11 for detecting the characteristic X-rays emitted from the sample 1 by irradiation with an electron beam is provided. is there. In FIG. 4, the same components are designated by the same reference numerals.

The control section 7 is supplied with a detection signal from the X-ray detector 11, and scans the sample 1 with the electron beam from the electron beam generating section 5 to perform elemental analysis of the scanning range. You can That is, in this embodiment, the SEM
Elemental analysis can be performed in addition to observation and SIM observation.

The electron microscope of this embodiment has the above-mentioned X-ray detector 1 in addition to the sectional evaluation of the sample in the procedure shown in FIG.
It is possible to perform cross-sectional evaluation by elemental analysis using 1. Specifically, instead of the cross-sectional SEM observation in step S20 of the evaluation procedure of FIG. 3 (or concurrently with the cross-sectional SEM observation), elemental analysis using the X-ray detector 11 is performed. In this elemental analysis, the control unit 7 controls the movement of the sample stage 8 so that the electron beam from the electron beam generating unit 5 is irradiated on the produced cross section, and further scans the cross section with the electron beam. Then, in synchronization with this scanning, characteristic X-rays at a plurality of measurement points are detected by the X-ray detector 11, and the control unit 7 displays the mapping information obtained from the detection signal on a display unit (not shown). Alternatively, after scanning the cross section with an electron beam, a necessary position is irradiated with the electron beam, and characteristic X-rays generated from the irradiation position are detected to perform elemental analysis.

In order to improve the accuracy of elemental analysis using the above X-ray detector 11, a sample stage with a temperature controller as shown in FIG. 5 may be used as the heat retaining section 2. This sample stage with a temperature controller has the same configuration as that shown in FIG. 2 except that the position of the temperature varying mechanism 10 and the position where the sample 1 is fixed are different. Figure 5
In the example, the temperature varying mechanism 10 is provided such that the side surface 10 a thereof is located at the edge 8 a of the sample stage 8, and the side surface 1 a of the sample 1 fixed on the temperature varying mechanism 10 is directly cross-section processed. You can do it.

When the sample stage with a temperature controller as described above is used, the right side (side surface 1a side) of the sample 1 is irradiated with an ion beam to cross-section the side surface 1
The section a can be processed to form a cross section therein. If the cross section is formed on the side surface 1a side of the sample 1 in this way, the cross section can be arranged close to the X-ray detector 11. The accuracy of elemental analysis is improved by bringing the cross section closer to the X-ray detector 11. Further, by tilting the sample stage toward the detector, the efficiency of detecting the characteristic X-rays generated is improved, and the accuracy of elemental analysis is further improved.

In addition, since the cross section can be arranged close to the electron beam generating section 5 by processing the cross section as described above, the accuracy of the SEM image obtained by using the electron detector 6 can be improved. Is possible.

In each of the above-described embodiments, when a sample is processed by an ion beam, shear stress, compressive stress and tensile stress, which are found in mechanical processing such as cutting and polishing, do not occur, so that hardness and brittleness are different. A sharp cross section can be prepared for a composite sample in which materials are mixed, a sample having voids, a fine structure of an organic substance formed on a substrate, a sample easily soluble in a solvent, and the like.

Further, since the sample temperature can be maintained at the set value, even if the sample contains a material whose state or morphology changes depending on the temperature, the layer will not be structurally destroyed at the desired set temperature. You can directly observe the specified position.

The sectional evaluation method in each of the above-mentioned modes is
Polymer structures on various substrates such as glass, microparticles,
It is effective for analysis of desired temperature of polymer structure including liquid crystal, particle dispersion structure in fibrous material, and temperature transition material. Further, it goes without saying that it is also effective for a sample that is easily damaged by an ion beam or an electron beam.

In the description of each embodiment, SEM observation, SIM observation, and elemental analysis are taken as an example.
The present invention is not limited to this, and can be applied to an apparatus for performing various analyzes such as mass spectrometry.

The sample stage with a temperature controller shown in FIG. 5 can also be used as the heat retaining section 2 of the scanning electron microscope for observing a cross section shown in FIG.

(Embodiment 3) In addition to the configurations of Embodiments 1 and 2, a reactive gas introducing pipe 13 is provided near the sample mounting table as shown in FIG. 6 so that the reactive gas is introduced near the sample 1 during FIB processing. May be introduced. The introduction pipe 13 is connected to the gas source container 15 via a valve 14. When you open the valve 14,
The reactive gas is introduced into the sample chamber 3 from the gas source container 15.

In this embodiment, depending on the selected ion beam, gas, temperature conditions, etc., gas etching or gas deposition with the assistance of the ion beam is performed, and the sample surface can be processed into an arbitrary shape. is there. By observing the machined surface as described above (SEM observation, SIM observation), information on the machined surface machined into a desired shape can be accurately obtained.

The gas inlet of the reactive gas inlet tube 13 is three-dimensionally arranged at a position where it does not interfere with the electron detector 6 and the beam system. A well known example of FIB assisted deposition is the deposition of tungsten using hexacarbonyl tungsten (W (CO) ₆ ) gas and Ga-FIB.

The metal in the gas can be deposited on the substrate by spraying an organometallic gas around the irradiation point of the FIB and reacting the FIB with the gas.

In the conventional FIB assist deposition apparatus having no cooling mechanism, there is a problem that the underlying material is removed by the FIB before the deposition by FIB assist deposition starts. The present invention is suitable as a method capable of forming a desired inorganic substance.

Further, an etching gas is blown around the irradiation point of the FIB to locally induce reactive etching at the beam irradiation portion, and high-speed and high-selection fine processing is possible.

The above-mentioned FIB-assisted etching and F
For various conditions of IB assist deposition, see
Processing conditions such as those described in JP-A-7-312196 can be used.

(Embodiment 4) In this embodiment, in addition to the configuration of Embodiment 1 as shown in FIG. 7, re-adhesion of residual gas in the sample chamber 3 and substances generated during processing to the sample 1 is prevented. A trap means 16 is provided for this purpose.

The trap means 16 is made of a metal having a high thermal conductivity, and is held at a temperature equal to or lower than the temperature of the sample 1 during the cooling of the sample 1.

In the present embodiment, when processing and observing the sample 1 while keeping it at room temperature or below,
There is an effect that the adhesion of impurities to the sample 1 can be prevented. For example, in the case of the FIB assisted deposition described above, the impurity layer is formed between the deposition layer and the sample to be processed, and the intended function may not be obtained in some cases, but in the present embodiment, the trap means 16 is used. Thus, formation of such an impurity layer is suppressed.

The trap means 16 is a detection system in which the mounting table on which the sample 1 is mounted, the ion beam generator 4, the electron beam generator 5, and the electron detector 6 are arranged.
And, it is arranged at a position that does not depend on the beam system during processing. Further, the trap means 16 is preferably arranged at a position as close to the sample 1 as possible in order to improve the trapping efficiency at a position where the detection and processing are not hindered. Further, the trap means 16 can be arranged in one or more places in the sample chamber 3 kept at a low pressure.

(Fifth Embodiment) Here, a case will be described in which the device of the present invention is used as a liquid crystal display device or a cross-sectional evaluation device in an organic semiconductor manufacturing process. Specifically, a mode in which the temperature of a sample having a relatively large area is adjusted will be described.

In a part of a large sample such as a glass substrate coated with liquid crystal used in a large-screen liquid crystal display device,
When it is desired to accurately evaluate the state of the cross section, the temperature of only the region near the processed portion may be locally adjusted, or the temperature of the entire substrate may be adjusted. When adjusting the temperature of the entire board,
It is preferable to cool the entire holder by providing a refrigerant flow pipe through which the refrigerant flows in a position facing the sample installation surface of the heat retaining section.

[0079]

EXAMPLES Hereinafter, an example in which a cross-section of a sample is actually evaluated using the sample evaluation apparatus of each of the above-described embodiments will be described.

Example 1 In this example, the scanning electron microscope for observing a cross section shown in FIG. 1 was used. As the heat-retaining unit 2, a sample stage with a temperature controller shown in FIG. 2 in which a unit with a low-temperature temperature varying mechanism is incorporated is used, and a liquid crystal (two-frequency drive liquid crystal manufactured by Chisso: DF01XX) is mounted on a glass substrate. Polymer structure containing (Polymerization monomer: HEMA, R167, HDDA mixed and polymerized with liquid crystal)
The cross-section evaluation of the sample in which was manufactured was performed by the following procedure.

First, the sample was fixed on a unit equipped with a low temperature temperature varying mechanism with a carbon paste, and this unit was set on the sample stage 8. After the sample stage 8 on which this sample was set was introduced into the sample chamber 3, the inside of the sample chamber 3 was evacuated to a predetermined low pressure.

Next, the set temperature was set to -100 ° C., and it was confirmed that the sample was kept at the evaluation temperature. The surface SEM observation was performed on the region including the cross-section observation position of the sample while always confirming the sample temperature. From the image obtained by the surface SEM observation, the substantially central portion of the sample was determined as the cross-section observation position.

Next, the determined cross-section observation position was irradiated with an ion beam to capture a SIM image. The ion beam at this time was performed under the condition that the observation mode was extremely weak. Specifically, a gallium ion source was used, and the acceleration voltage was 30 kV, the beam current was 20 pA, and the beam diameter was about 30 nm. And
The cross-section processing position was specified for the captured SIM image.

Next, the designated cross-section processing position was subjected to FIB processing (rough processing). Specifically, a rectangular concave portion having a depth of 30 μm and a square of 40 μm was formed at a cross-section processing position with an acceleration voltage of 30 kV, a beam current of 50 nA, and a beam diameter of about 300 nm. In this rough processing, the processing was performed step by step under gradually weak conditions, and during processing, the cross section of the sample being processed was sometimes observed by SEM to confirm whether or not the processing was performed up to a desired position. When the processing was almost completed, the beam was switched to the electron beam, the processed cross section was adjusted so that the electron beam could be scanned at an angle of about 60 °, and the cross section SEM observation was performed.

After confirming that the desired position has been processed, the beam is switched to the ion beam, and further, as the finishing process for improving the cross-section processing accuracy, rough processing is performed under the same weak condition as in the SIM observation. The cross-section processing position that was roughly processed with a beam thinner than that was further processed. FIG. 8A is a schematic view of a cross section produced by this FIB processing. The ion beam 2 is placed on the sample 30 almost in the center.
A rectangular recess is formed by irradiation with 0.

Finally, SEM observation of the cross section of the sample manufactured as described above was performed. FIG. 8B is a schematic diagram showing the irradiation of the electron beam during the SEM observation. Figure 8
For the cross section of the sample 30 shown in FIG.
Was irradiated at an angle of about 60 °, and the electron beam 21 was used to scan the cross section of the sample 30 for SEM observation. The condition of SEM observation at this time is an acceleration voltage of 800 V.
Therefore, the photographing magnification was up to 50,000 times. By this SEM observation, it was possible to observe that the liquid crystal was wrapped in the polymer layer.

As described above, in this embodiment, since the FIB processing was performed while maintaining the temperature of the sample at −100 ° C.,
The cross-section could be processed without sagging the liquid crystal layer during processing. Further, since the SEM observation was possible in the same sample chamber while maintaining the temperature as it was, it was possible to observe the cross section of the state where the liquid crystal was present in the polymer.

(Example 2) In this example, a cross section of polymer particles (polystyrene) produced on a PET substrate was evaluated as follows by using the sample stage with a temperature controller shown in FIG. I went by the procedure.

The set temperature is set to about 10 ° C., and one side of the sample is cut into a length of about 20 μm and a depth of about 6 μm.
Processing of about 0 μm was performed. In order to prevent charge-up before FIB processing, platinum having a film thickness of about 30 nm was vapor-deposited on the sample surface by an ion beam sputtering method. Next, tungsten hexacarbonyl was introduced, FIB was irradiated so as to cover the polymer particles, and a tungsten film was deposited to form a protective film. Other than that, finish processing was performed under the same conditions as in Example 1 above. FIG. 9A is a schematic view of a cross section produced by this FIB processing. A rectangular recess is formed by irradiation of the ion beam 20 on one side surface (corresponding to the side surface 1a in FIG. 5) of the sample 31.

Next, when the sample 31 was tilted and observed by SEM, it was found that the polymer particles were in close contact with the substrate. The conditions at this time are: acceleration voltage 15 kV, magnification ~
Up to about 30,000 times.

Next, when characteristic X-rays emitted from the cross section of the sample 31 were taken during the SEM observation and a mapping image was obtained (elemental analysis), it was found that aluminum was dispersed in the polymer. FIG. 9B is a schematic diagram showing irradiation of an electron beam and emission of characteristic X-rays in the elemental analysis. The cross section of the sample 31 shown in FIG. 9A is irradiated with the electron beam 21 perpendicularly, and characteristic X-rays are emitted from the cross section of the sample 31 in response to this irradiation. Elemental analysis was performed by detecting the emitted characteristic X-rays.

Although the method of evaluating the cross section of the sample has been described above, the present invention is not limited to this. For example, the present invention includes a configuration in which substances adhering to the surface are removed, the surface to be observed is exposed, and the surface is observed.

Further, the exposing means may be any means as long as it can expose the surface for which information is to be obtained, and in addition to the ion beam generating means, a laser beam generating means or the like can be suitably implemented.

[0094]

As described above, according to the present invention,
Since the surface for which information is desired is exposed and the information is acquired while the sample that changes in state and morphology due to temperature changes is adjusted to the desired temperature, accurate information for the surface for which information is desired can be acquired. Becomes

Further, when the present invention is used as a cross-section evaluation apparatus, cross-section processing and observation (SEM) are carried out while maintaining a sample whose state and morphology change due to temperature change at a desired temperature.
(Observation or SIM observation) and further elemental analysis can be performed, so that the fine cross-sectional morphology of the sample can be accurately evaluated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a scanning electron microscope for observing a cross section, which is a first embodiment of a sample evaluation apparatus of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a sample stage with a temperature controller, which is an example of a heat retaining unit shown in FIG.

FIG. 3 is a flowchart showing a procedure of evaluating a cross section of a sample by using the scanning electron microscope for cross section observation shown in FIG.

FIG. 4 is a schematic configuration diagram of a scanning electron microscope for observing a cross section, which is a second embodiment of the sample evaluation apparatus of the present invention.

5 is a block diagram showing a schematic configuration of a sample stage with a temperature controller, which is an example of a heat retaining unit shown in FIG.

FIG. 6 is a schematic configuration diagram of a scanning electron microscope for observing a processed surface, which is a third embodiment of the sample evaluation apparatus of the present invention.

FIG. 7 is a schematic configuration diagram of a scanning electron microscope for observing a processed surface, which is a fourth embodiment of the sample evaluation apparatus of the present invention.

8A is a schematic view showing an example of a cross section manufactured by FIB processing, and FIG. 8B is a SEM view of the cross section shown in FIG. 8A.
It is a schematic diagram which shows the state at the time of observing.

9A is a schematic diagram showing an example of a cross section produced by FIB processing, and FIG. 9B is a schematic diagram showing a state when elemental analysis is performed on the cross section shown in FIG. 9A.

[Explanation of symbols]

1, 30, 31 samples 2 insulation 3 sample chamber 4 Ion beam generator 5 Electron beam generator 6 Electronic detector 7 control unit 7a Temperature control unit 8 sample stage 9a, 9b Thermometer 10 Temperature variable mechanism 11 X-ray detector 20 ion beam 21 electron beam

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01J 37/317 H01J 37/317 DF term (reference) 2G001 AA03 AA05 AA10 BA05 BA07 BA30 CA01 CA03 CA10 DA06 GA04 GA06 GA17 KA20 LA20 MA05 NA06 NA17 PA07 PA12 RA03 RA04 5C001 BB01 BB02 BB03 CC04 CC08 5C033 NN01 NN04 UU03 UU04 5C034 DD09

Claims (18)

[Claims] 1. A mounting table for mounting a sample, a temperature adjusting means for adjusting the temperature of the sample, an exposing means for exposing a surface of the sample from which information is to be acquired, and the exposing And an information acquisition unit for acquiring information about the surface exposed by the unit. 2. The exposure by the exposure means and the acquisition of information by the information acquisition means are performed in a state where the temperature of the sample is adjusted to a preset temperature by the temperature adjustment means. Information acquisition device described in. 3. The information acquisition apparatus according to claim 1, wherein the temperature adjusting unit includes a cooling unit that cools the sample to a temperature equal to or lower than room temperature. 4. The mounting table, the exposing means, and the information acquiring means are arranged in a chamber whose atmosphere can be controlled,
The information acquisition device according to claim 1, further comprising a trap unit that traps a gas remaining in the chamber. 5. A mounting table for mounting a sample, temperature adjusting means for adjusting the temperature of the sample, ion beam generating means for irradiating the sample with an ion beam, and for the sample And an electron beam generating means for irradiating an electron beam, and a detecting means for detecting an emission signal emitted from a predetermined portion of the sample in response to the irradiation of the ion beam or the irradiation of the electron beam. 6. The sample evaluation apparatus according to claim 5, wherein the predetermined portion of the sample is a portion whose cross section is cut out by the ion beam. 7. The sample evaluation apparatus according to claim 5, wherein the predetermined portion of the sample is a portion processed by the ion beam. 8. The sample evaluation apparatus according to claim 5, wherein the temperature adjusting unit includes a cooling unit that cools the sample to a temperature equal to or lower than room temperature. 9. The mounting table, the ion beam generating means, the electron beam generating means, and the detecting means are arranged in a chamber whose atmosphere can be controlled, and trap means for trapping gas remaining in the chamber is further provided. The sample evaluation apparatus according to claim 5, which has. 10. The section of the sample is cut out or processed by irradiating a predetermined portion of the sample with the ion beam, and the surface of the predetermined section or the section is cut or processed by the ion beam or the electron beam. Image information on the surface of the predetermined portion or the surface on which the cross section is cut out or processed based on emission signals from a plurality of points detected by the detection means in synchronization with the scanning. The sample evaluation apparatus according to claim 5, further comprising a control unit for acquiring 11. The temperature adjusting means includes a temperature varying mechanism in a portion where the sample is fixed, the fixed sample is movable and rotatable in a predetermined direction, and one of the temperature varying mechanism. A first temperature detecting means attached to the temperature detecting means for detecting the temperature in the vicinity of the sample fixed to the temperature changing mechanism; and in the temperature changing mechanism based on the temperature detected by the first temperature detecting means. The sample evaluation device according to claim 5, further comprising: a temperature control unit that adjusts the temperature and keeps the sample at a preset temperature. 12. The sample evaluation apparatus according to claim 11, wherein a side surface of the sample fixed on the temperature varying mechanism is irradiated with an ion beam. 13. The temperature control means further comprises second temperature detection means for directly detecting the temperature of the sample and display means for displaying the temperature detected by the second temperature detection means. The sample evaluation device according to claim 11 or 12, which is characterized. 14. The temperature control means adjusts the temperature in the temperature varying mechanism based on the temperatures detected by the first and second temperature detecting means. Sample evaluation device. 15. The emission signal is a secondary electron or a characteristic X.
The sample evaluation device according to any one of claims 5 to 14, wherein the sample evaluation device is a line. 16. The detecting means comprises a first detector for detecting secondary electrons and a second detector for detecting characteristic X-rays. The sample evaluation device described in the item. 17. A first step of adjusting the temperature of a sample, a second step of irradiating a predetermined portion of the sample with an ion beam to cut out or process a cross section, and a step of cutting or processing the cross section. Scanning the cut surface with an electron beam, and obtaining an image of the cut or processed surface of the cross section from an emission signal emitted from a plurality of points in synchronization with the scanning. The sample evaluation method characterized by the above. 18. The emission signal is a secondary electron or a characteristic X.
18. The sample evaluation method according to claim 17, which is a line or both of them.