JP2003194681A - TEM sample preparation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a TEM (transmitance electron microscope) sample preparation method capable of preparing a sample changing the TEM observation direction, and improving the workability of the sample preparation. <P>SOLUTION: This method is constituted so as to laminate the observation sample 4 by using an existing FIB (focused ion beam) device, and to perform an extracting and sticking work of the laminated sample 4 by using an optical microscope having an existing micromanipulator equipped with an electrostatic pincette 10. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a sample for TEM observation, in which a TEM sample for observation in a cross-sectional direction at a plane observation location after plane observation is produced, or a plane observation at a cross-section observation location after cross-section observation. The present invention relates to a TEM sample preparation method for preparing a TEM sample for cross-section observation or cross-direction observation.

[0002]

2. Description of the Related Art Conventionally, TEM (transmission electron microscope, ST
As a method for producing a sample to be observed with an EM (including a scanning transmission electron microscope), the method described in, for example, JP-A-2000-146781 is known. The sample preparation method described in this publication is to prepare a cross-section observation sample at the same observation location from a sample after plane observation by applying a micro-sampling method. The observed portion was processed into a minute thin piece sample for cross-section observation using FIB (Focused Ion Beam), and the processed minute thin piece sample was extracted using an electronically controlled probe installed in the FIB device, and the extracted sample Was attached to the observation mesh, and the micro-thin piece sample attached to the observation mesh was further thinned to a thickness for observation using FIB, and TEM cross-section observation was performed using the thinned cross-section observation TEM sample.

A series of operations from preparation of a sample to observation have been performed by a system in which various devices are integrated.

As a concrete work procedure of the above-mentioned sample preparation, a TEM for plane observation is first carried out by polishing and ion thinning.
A sample is prepared and TEM plane observation is performed (step 1).
Next, the plane observation TEM sample after the plane observation is introduced into the FIB apparatus (step 2), and the cross-section observation portion is extracted from the plane observation TEM sample using the FIB and processed (step 3). After that, the sample excised and processed using the deposition function of the FIB device is attached to the probe (step 4). Then, the probe to which the sample is attached is moved, and the sample attached to the probe is transferred and attached to the FIB / TEM shared observation holder using the deposition function of the FIB device (step 5), FIB
The probe is separated from the sample by the milling function of (step 6). Next, the sample attached to the observation holder is subjected to finishing (thinning) processing for cross-section observation using FIB, and a TEM sample for cross-section observation is produced (step 7). Using the prepared TEM sample for cross-section observation, T
EM observation is performed (step 8).

Roughly speaking, a TEM sample for cross-section observation was prepared from a TEM sample for plane observation through the above steps. In such a creation process, the above steps 2 to 7 were performed in the FIB device included in the system. Therefore, in the FIB device, 1
Only one operation could be performed, and the sample extraction and sticking operations in steps 3 and 4 and the finishing process in step 7 could not be performed in parallel at the same time.

[0006]

As described above,
In conventional TEM sample preparation using FIB, all the work was done in a system where the device was integrally configured. For this reason, a plurality of works cannot be simultaneously performed in parallel in the apparatus for performing FIB, which causes a problem that workability is deteriorated. Further, conventionally, it was not possible to prepare a TEM sample for plane observation or a TEM sample for cross-section observation in different directions from a TEM sample for cross-section observation.

Therefore, the present invention has been made in view of the above, and an object of the present invention is to enable the preparation of a sample with a different TEM observation direction and to improve the workability in the sample preparation. It is to provide a manufacturing method.

[0008]

In order to achieve the above-mentioned object, the first means for solving the problems is to use a milling method or FIB (focused ion beam), and use TEM (transmission electron microscope) or STEM ( A first step of producing a flat surface observation sample to be observed with a scanning transmission electron microscope),
The plane observation sample produced by the first step is used as a TEM.
After observing with, the desired cross-section observation point is searched for from the flat-plane observation sample after the observation, and a rectangular deposition film is formed on the searched cross-section observation point using the deposition function provided in the FIB device. Second step and using the FIB apparatus, a part of the cross-section observation sample on which the deposition film is formed by the second step is thinned, and the thinned cross-section observation sample is separated from other sample parts. Third step of forming a notch for separation and thinning the cross-section observation point of the thinned sample to the extent that it can be observed, and electrostatic tweezers equipped with a micromanipulator and charged. And a fourth step of adsorbing the cross-section observation sample thinned in the third step to separate the cross-section observation sample thinned from other sample portions, and the fourth step.
And a fifth step of attaching the cross-section observation sample adsorbed to the electrostatic tweezers to the supporting film of the supporting member in the step of.

The second means is the milling method or FIB.
A first step of producing a cross-section observation sample to be observed with a TEM (transmission electron microscope) or STEM (scanning transmission electron microscope) using (focused ion beam), and a cross section produced by the first step After observing the observation sample by TEM, find the desired plane or different-direction cross-section observation point from the cross-section observation sample after observation, and use the deposition function provided in the FIB device to observe the found plane or different-direction cross section A second step of forming a rectangular deposition film on the upper part of the portion, and the second step using the FIB apparatus.
Part of the sample for observing the cross-section or the different direction cross section on which the deposition film is formed is thinned by the step of, and a cut is formed to separate the thinned sample for observing the cross section or different direction cross-section from other sample parts. Observation of sliced plane or cross-section in different direction Third step of further thinning the plane or cross-section observation point of sample to the extent that it can be observed, and electrostatic tweezers charged in the micromanipulator A fourth step of adsorbing the plane or different-direction cross-section observation sample thinned in the third step, and separating the thin-plane or different-direction cross-section observation sample from other sample portions; And a fifth step of attaching the flat surface or different-direction cross-section observation sample adsorbed to the electrostatic tweezers in the fourth step to the supporting film of the supporting member.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 9 are views showing the procedure of a TEM sample manufacturing method according to an embodiment of the present invention. The feature of this embodiment is that an existing FIB (Focused Ion Beam) apparatus and a micromanipulator system equipped with an existing electrostatic tweezers used for gene manipulation in the field of biotechnology are used,
A TEM sample for cross-section observation of a desired portion of a plane sample observed by TEM (including STEM) is prepared, or a TEM sample for plane observation and a TEM sample for cross-section observation of different direction of a cross-section sample observed by TEM are produced. To do.

First, for a sample after plane observation by TEM, TE for cross-section observation of a desired portion confirmed by plane observation.
A manufacturing procedure for manufacturing the M sample will be described.

First, the milling method or FI
Using B, a desired observation portion of the sample is thinned to prepare a TEM sample for plane observation. When manufactured by the milling method, FIG. 1 (FIG. 1A is a plan view, FIG.
As shown in FIG. 2C, which is an enlarged view of a partial cross section of FIG. 1B, the observation target portion 2 is thinned with respect to the entire sample 1. On the other hand, in the case of using the FIB, as shown in FIG. 2, the portion of the sample 1 to be observed 2 is cut and thinned. In any of the manufacturing methods, the remaining film thickness 3 at the desired observation portion 2 is set to a thickness at which the state of the desired observation portion 2 can be observed with a TEM. For example,
In the case of general semiconductor device failure analysis, the remaining film thickness is 3
Is about 0.1 μm to 1.0 μm (step 1).

Next, the plane observation T produced in the above process
The EM sample is observed on a plane by TEM. The observation result is output as, for example, a photograph or an electronic image, and the position and shape of the desired observation portion 2 are confirmed (step 2).

Next, in order to avoid damage to the sample surface by the ion beam when the TEM sample for cross-section observation is manufactured from the TEM sample for plane observation using FIB, FIG.
As shown in, the sputtered film of Pt, Au, etc. on the surface of sample 4,
A protective film 5 made of a vapor deposition film of carbon or the like is formed, and the sample surface is covered with the protective film 5 (step 3).

Next, the sample 4 having the protective film 5 formed thereon was subjected to FI.
It is introduced into the apparatus B and a desired cross-section observation point 2 that is the same as the plane observation desired point 2 is searched (step S4).

Subsequently, a rectangular parallelepiped deposition film 6 is formed on the surface of the cross-section observation desired portion 2 of the sample 4 as shown in FIG. 4 by using the deposition function of the FIB apparatus.
The deposition film 6 is made of, for example, tungsten, platinum, carbon, or a silicon oxide film that can be formed by an FIB apparatus, and has a rectangular parallelepiped height of about 10 μm and a long side (width).
The length is about 10 μm and the short side (thickness) is about 2 to 4 μm. The deposition film 6 is for facilitating the work of extracting the TEM sample for cross-section observation with electrostatic tweezers equipped in the micromanipulator described later (step 5).

Next, using the FIB, as shown in FIG. 5 (FIG. 5A is a plan view and FIG. 5B is a perspective view), a focused ion beam is applied to the sample 4 shown in FIG. 4 from above. Milling is performed by irradiating 7 to thin the sample 4 and a part of the deposition film 6 (step 6).

Next, before the desired portion 2 for cross-section observation is made to have the final film thickness, the thinning process is completed with a film thickness of, for example, (final film thickness + 0.5 μm). After that, sliced sample 4 is
In order to cut out the thinned sample 4 as shown in FIG. 6 (FIG. 6A is a front view, FIG. 6B is a plan view) by irradiating a focused ion beam from above with tilting at an angle of 60 degrees or 60 degrees. The notch 8 is formed on the height direction side of the sample 4. At this time, if all the cuts 8 are made in the sample 4, the thinned sample 4
Are removed, the uncut portion 9 is provided in the deposition film 6 to prevent the removal (step 7).

Next, when there are a plurality of desired cross-section observation points 2, the operations shown in steps 4 to 7 are repeated for the desired observation points 2 (step 8).

Next, the inclination of the sample 4 is returned to its original state, and final finishing processing is performed by using the FIB to thin all the desired observation portions 2 to such an extent that observation is possible (step 9).

Next, the sliced sample 4 is taken out from the FIB apparatus and transferred to an optical microscope incorporating a micromanipulator system (step 10).

Next, the micromanipulator system is equipped with hydraulically driven electrostatic tweezers, which is made of glass and has a diameter of about 1 to 10 μm. Using this electrostatic tweezers, the electrostatic tweezers 10 are pressed against the side surface of the thinned sample 4 as shown in FIG. 7A, and the thinned sample 4 is left uncut as shown in FIG. 7B. Separate from 9. At this time, the electrostatic tweezers 10 are charged with static electricity in advance, and the separated thinned sample 4 is adsorbed by the static electricity charged by the electrostatic tweezers 10 (step 11).

Next, a metal mesh 12 with an organic support film 11 as shown in FIG. 8 (FIG. 8A is a plan view, and FIG. 8B is a sectional view) is prepared, and FIG. ) Is a plan view and (B) is a cross-sectional view).
The thinned sample 4 adsorbed by the electrostatic tweezers 10 is attached to the support film 11 on 2. Generally, electrostatic tweezers 1
Since the adhesive force of the organic support film 11 is stronger than the electrostatic force charged to 0, the exfoliated sample 4 has electrostatic tweezers 10
To the organic support film (step 12).

Next, when there are a plurality of desired observation points 2, the above steps 11 and 12 are repeated (step 13).

Finally, the sliced sample 4 attached to the metal mesh 12 is introduced into a TEM holder for observation,
TEM observation is performed (step 14).

As described above, in the above embodiment, the thinning work of the sample for cross-section observation in the above Step 4 to Step 9 is performed in the FIB apparatus, and the above Step 1 is performed.
The cutting out and sticking work of the sliced sample from 0 to step 13 is performed by an optical microscope with a micromanipulator system equipped with electrostatic tweezers of a device different from the FIB device.

As a result, it becomes possible to simultaneously carry out the sample thinning work and the thinned sample cutting out and pasting work in parallel. Therefore, workability is improved and throughput can be increased. Also, FIB
There is no need to make special modifications such as incorporating an electronically controlled probe into the device, and it is easy to do by simply introducing an optical microscope with a micromanipulator system equipped with existing electrostatic tweezers into the existing FIB device. can do.

Further, by forming the deposition film 6 on the rectangular parallelepiped on the desired portion of the sample for observation, it is possible to obtain a thin sample having a wide cross-sectional area, and as a result, electrostatic tweezers equipped on the micromanipulator. By this, it becomes possible to easily extract the thinned sample.

Next, referring to FIGS. 1 to 9, an embodiment in the case of producing a TEM sample for observing a plane or a different direction cross-section of an observation desired portion confirmed by cross-section observation of a sample after cross-section observation by TEM will be described. explain.

First, the milling method or FI
Using B, the desired observation portion of the sample is thinned to prepare a TEM sample for cross-section observation. When manufactured by the milling method, FIG. 1 (FIG. 1A is a plan view, FIG.
As shown in FIG. 2C, which is an enlarged view of a partial cross section of FIG. 1B, the observation target portion 2 is thinned with respect to the entire sample 1. On the other hand, in the case of using the FIB, as shown in FIG. 2, the portion of the sample 1 to be observed 2 is cut and thinned. In any of the manufacturing methods, the remaining film thickness 3 at the desired observation portion 2 is set to a thickness at which the state of the desired observation portion 2 can be observed with a TEM. For example,
In the case of general semiconductor device failure analysis, the remaining film thickness is 3
Is about 0.1 μm to 1.0 μm (step 1).

Next, the T for cross-section observation manufactured in the above process
The EM sample is observed on a plane by TEM. The observation result is output as, for example, a photograph or an electronic image, and the position and shape of the desired observation portion 2 are confirmed (step 2).

Next, in order to avoid damage to the sample surface due to the ion beam when a plane observation TEM sample is produced from a cross-section observation TEM sample using FIB, FIG.
As shown in, the sputtered film of Pt, Au, etc. on the surface of sample 4,
A protective film 5 made of a vapor deposition film of carbon or the like is formed, and the sample surface is covered with the protective film 5 (step 3).

Then, the sample 4 having the protective film 5 formed thereon was subjected to FI.
It is introduced into the apparatus B, and the desired point 2 for planar observation that is the same as the desired point 2 for observing a cross section is searched (step S4).

Subsequently, as shown in FIG. 4, a rectangular parallelepiped deposition film 6 is formed on the surface of the desired spot 2 for planar observation of the sample 4 by using the deposition function of the FIB apparatus.
The deposition film 6 is made of, for example, tungsten, platinum, carbon, or a silicon oxide film that can be formed by an FIB apparatus, and has a rectangular parallelepiped height of about 10 μm and a long side (width).
The length is about 10 μm and the short side (thickness) is about 2 to 4 μm. The deposition film 6 is for facilitating the work of extracting the TEM sample for planar observation with electrostatic tweezers equipped on the micromanipulator described later (step 5).

Next, using the FIB, as shown in FIG. 5 (FIG. 5A is a plan view and FIG. 5B is a perspective view), a focused ion beam is applied to the sample 4 shown in FIG. 4 from above. Milling is performed by irradiating 7 to thin the sample 4 and a part of the deposition film 6 (step 6).

Next, before the final plane observation desired portion 2 is made to have the final film thickness, the thinning process is completed with a film thickness of, for example, (final film thickness + 0.5 μm). After that, sliced sample 4 is
In order to cut out the thinned sample 4 as shown in FIG. 6 (FIG. 6A is a front view, FIG. 6B is a plan view) by irradiating a focused ion beam from above with tilting at an angle of 60 degrees or 60 degrees. The notch 8 is formed on the height direction side of the sample 4. At this time, if all the cuts 8 are made in the sample 4, the thinned sample 4
Are removed, the uncut portion 9 is provided in the deposition film 6 to prevent the removal (step 7).

Next, when there are a plurality of desired spots 2 for planar observation, the operations shown in steps 4 to 7 are repeated for the desired spots 2 for observation (step 8).

Next, the inclination of the sample 4 is returned to the original state, and the final finishing process is performed by using the FIB to thin all the desired observation portions 2 to such an extent that observation is possible (step 9).

Next, the sliced sample 4 is taken out from the FIB apparatus and transferred to an optical microscope incorporating a micromanipulator system (step 10).

Next, the micromanipulator system is equipped with hydraulic driven electrostatic tweezers, which is made of glass and has a diameter of about 1 to 10 μm. Using this electrostatic tweezers, the electrostatic tweezers 10 are pressed against the side surface of the thinned sample 4 as shown in FIG. 7A, and the thinned sample 4 is left uncut as shown in FIG. 7B. Separate from 9. At this time, the electrostatic tweezers 10 are charged with static electricity in advance, and the separated thinned sample 4 is adsorbed by the static electricity charged by the electrostatic tweezers 10 (step 11).

Next, a metal mesh 12 with an organic support film 11 as shown in FIG. 8 (FIG. 8A is a plan view and FIG. 8B is a cross-sectional view) is prepared. ) Is a plan view and (B) is a cross-sectional view).
The thinned sample 4 adsorbed by the electrostatic tweezers 10 is attached to the support film 11 on 2. Generally, electrostatic tweezers 1
Since the adhesive force of the organic support film 11 is stronger than the electrostatic force charged to 0, the exfoliated sample 4 has electrostatic tweezers 10
To the organic support film (step 12).

Next, when there are a plurality of desired observation points 2, the above steps 11 and 12 are repeated (step 13).

Finally, the sliced sample 4 attached to the metal mesh 12 was introduced into a holder for TEM observation,
TEM observation is performed (step 14).

As described above, in the above embodiment, the thinning work of the sample for plane observation in the above steps 4 to 9 is performed in the FIB apparatus, and the thinning sample in the above steps 10 to 13 is performed. The cutting and pasting work is performed by an optical microscope with a micromanipulator system equipped with electrostatic tweezers of a device different from the FIB device.

Also in such an embodiment, the same effect as in the previous embodiment can be obtained. In addition, it becomes possible to manufacture a TEM sample for plane observation or a TEM sample for cross-section observation in different directions from a sample after cross-section observation by TEM, which is confirmed by cross-section observation.

[0047]

As described above, according to the present invention, the sample for observation is thinned by using the existing FIB device, and the existing optical microscope with the micromanipulator equipped with electrostatic tweezers is used. By doing so, the work of extracting and attaching the sliced sample was performed, so by operating each device independently, it is possible to perform each work in parallel at the same time, improving workability, The processing throughput can be increased.

Further, by using the existing apparatus, it becomes possible to easily introduce a system for sample preparation, and it is possible to reduce the cost.

Further, a TEM sample for plane observation or a TEM sample for different-direction cross-section observation of a desired portion confirmed by cross-section observation can be prepared from the sample after cross-section observation by TEM.

[Brief description of drawings]

FIG. 1 is a diagram showing a sample manufactured by a milling method in a procedure of a TEM sample manufacturing method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a sample manufactured by FIB in the procedure of the TEM sample manufacturing method according to the embodiment of the present invention.

FIG. 3 is a diagram showing a sample on which a protective film is formed in the procedure of the TEM sample manufacturing method according to the embodiment of the present invention.

FIG. 4 is a diagram showing a sample in which a rectangular parallelepiped deposition film is formed in the procedure of the TEM sample manufacturing method according to the embodiment of the present invention.

FIG. 5 is a view showing a sample thinned by FIB in the procedure of the TEM sample manufacturing method according to the embodiment of the present invention.

FIG. 6 is a view showing a sample in which a cutting process is performed in the procedure of the TEM sample manufacturing method according to the embodiment of the present invention.

FIG. 7 is a diagram showing how a sample is separated in the procedure of the TEM sample manufacturing method according to the embodiment of the present invention.

FIG. 8 is a diagram showing a metal mesh with a support film in the procedure of the TEM sample manufacturing method according to the embodiment of the present invention.

FIG. 9 is a diagram showing a sample attached to a support film of a metal mesh in the procedure of the TEM sample manufacturing method according to the embodiment of the present invention.

[Explanation of symbols]

1,4 sample 2 desired observation point 3 Leftover film thickness 5 protective film 6 Deposition film 7 ion beam 8 notches 9 Uncut portion 10 electrostatic tweezers 11 Supporting membrane 12 metal mesh

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Naohisa Suzuki             25-1 Honmachi, Kawasaki-ku, Kawasaki-shi, Kanagawa             Toshiba Microelectronics Co., Ltd. F term (reference) 2G052 CA04 CA45 EC01 GA32 GA33                       GA34 GA35 JA07                 5C001 BB07 CC01

Claims (2)

[Claims] 1. A TEM (transmission electron microscope) or S using a milling method or FIB (focused ion beam).
A first step of producing a plane observation sample to be observed with a TEM (scanning transmission electron microscope), and a TEM of the plane observation sample produced by the first step.
After observing with, the desired cross-section observation point is searched for from the flat-plane observation sample after the observation, and a rectangular deposition film is formed on the searched cross-section observation point using the deposition function provided in the FIB device. Second step and using the FIB apparatus, a part of the cross-section observation sample on which the deposition film is formed by the second step is thinned, and the thinned cross-section observation sample is separated from other sample parts. Cross-section observation in which a cut for separation is formed, and the thinned cross-section observation point of the sample is further thinned to an observable third step, and electrostatic tweezers equipped with a micromanipulator and charged And a fourth step of adsorbing the cross-section observation sample thinned in the third step to separate the cross-section observation sample thinned from other sample portions, and the static step in the fourth step. TEM sample preparation method characterized by having a fifth step of attaching the cross-section observation sample adsorbed to the forceps supporting film of the support member. 2. A TEM (transmission electron microscope) or S using a milling method or FIB (focused ion beam).
The first step of producing a cross-section observation sample to be observed by a TEM (scanning transmission electron microscope), and the TEM cross-section observation sample produced by the first step.
After observing, the desired plane or different-direction cross-section observation point is searched for from the cross-section observation sample after observation, and the deposition function provided in the FIB device is used to form a rectangle on top of the found plane or different-direction cross-section observation point. A second step of forming a deposition film having a shape; and using the FIB apparatus, thinning a part of the flat surface or different direction cross-section observation sample on which the deposition film is formed by the second step, Sliced flat surface or different-direction cross-section observation Cuts are formed to separate the sample from other sample parts, and the thinned flat surface or different-direction cross-section observation sample flat surface or different-direction cross-section observation point can be observed To the third step, and to the electrostatic tweezers equipped on the micromanipulator and charged, the plane or different-direction cross-section observation sample thinned in the third step. A fourth step of adsorbing and separating the sliced flat surface or different-direction cross-section observation sample from another sample portion; and a flat surface or different-direction cross-section observation sample adsorbed to the electrostatic tweezers in the fourth step. And a fifth step of adhering to the supporting film of the supporting member.