KR20180054287A - method for manufacturing specimen for internal structure analysis of film comprising inorganic layers - Google Patents

Abstract

Disclosed is a method for manufacturing a specimen for internal structure analysis of a film comprising inorganic layers that can analyze an internal structure of the film having thickness of dozens of μm or more, without damaging to the inorganic layers existing in the film. The method includes the steps of: cutting a film by a microtome method so that an internal structure is revealed, thereby forming a first preliminary specimen; positioning a protective layer on a top surface of the first preliminary specimen at an analyzing point, and machining the first external preliminary specimen on the basis of the protective layer by a focused ion beam method, thereby forming a second preliminary specimen; cutting the second preliminary specimen by the focused ion beam method to separate a portion containing the analyzing point positioned below the protective layer, thereby forming a third preliminary specimen; and milling the third preliminary specimen to analyze the analyzing point at thickness required for performing TEM analysis, thereby forming a specimen for TEM analysis.

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a specimen for analyzing an internal structure of a film including an inorganic layer,

The present invention relates to a method for preparing a specimen for analyzing an internal structure of a film including an inorganic layer.

The high-performance film applied to the information electronics field is composed of various layers. It is necessary to accurately analyze the thicknesses and components of each layer of such a high-performance film in order to develop the technology in this technical field. The importance of analytical equipment and techniques for analyzing films structurally or chemically is increasing. Among various methods, the analysis technique using a transmission electron microscope (hereinafter referred to as TEM) is considered to be one of the best techniques in terms of decomposition function and application.

Although the technique of analyzing a film using the above-mentioned TEM provides a lot of information, it is necessary to prepare an optimum sample in order to obtain an analysis result suitable for a desired purpose. There are various methods for preparing the specimen to be used in the TEM, such as mechanical polishing, ion thinning, microtome, and focused ion beam (FIB).

Conventionally, a microtome method has been mainly utilized. However, since the microtome method cuts the film with a glass knife or a diamond knife, it may be difficult to maintain the original shape depending on the film. Particularly, when the film includes an inorganic layer, the structure may be deformed due to physical impact caused by the microtome method, so that the thickness of the layer can not be accurately measured.

A focused ion beam method is known as a method capable of preparing a specimen without physical impact by making up for the disadvantages of the microtome method. For example, U.S. Patent No. 6,080,991 discloses a method for producing thin specimens for TEM analysis using a focused ion beam method. However, such a focused ion beam method is disadvantageous in that the processing region is very small and processing can be performed only within 10 占 퐉 in the depth direction. In analyzing the inside of the film, since the inorganic layer, which is a layer of interest, existing inside is often away from the film surface by several tens of micrometers or more, it is impossible to manufacture a TEM specimen using the conventional focused ion beam method.

Accordingly, there is a need in the art for an improved method of TEM sample preparation for analyzing inorganic layers present in the film.

In analyzing the internal structure of a film including an inorganic layer, the microtome method and the focused ion beam method are simultaneously applied by a specific method, so that the inorganic layer located inside the film is separated from the film surface by several tens of micrometers or more The present invention provides a method for manufacturing a specimen used in a TEM capable of accurately analyzing the structure of an analysis point.

According to a first aspect of the present invention,

(A) preparing a first preliminary specimen by cutting the film by a microtome method so that the internal structure of the film is exposed;

(b) placing a protective layer on the upper surface of the analysis point in the first preliminary specimen and fabricating an outer first preliminary specimen using a focused ion beam method based on both sides of the protective layer to produce a second preliminary specimen step;

(c) preparing a third preliminary specimen by cutting with a focused ion beam method to separate a portion of the second preliminary specimen including an analysis point located under the protective layer; And

(d) milling the third preliminary specimen so as to analyze the analysis point at a thickness capable of TEM analysis, thereby preparing a specimen for TEM analysis, A method for fabricating a specimen for structural analysis is provided.

According to an embodiment of the present invention, in the step (a), the microtome method is characterized in that the film is cut using a glass knife or a diamond knife.

According to an embodiment of the present invention, in the step (a), cutting is performed in a direction perpendicular to the layer including the analysis point at a position separated by 1 to 10 μm from the analysis point.

According to one embodiment of the present invention, in the step (b), the protective layer may be formed of a platinum (Pt) or tungsten (W) coating, Is formed.

According to one embodiment of the present invention, in the step (b), the processing by the focused ion beam method is performed by slope cutting the first preliminary specimen with a predetermined distance from both sides of the protective layer, And then polishing the first preliminary specimen to both sides of the layer.

According to an embodiment of the present invention, the slope cutting is performed under a beam current condition of 9 to 21 nA.

According to one embodiment of the present invention, the polishing is performed with a beam current condition of 2 to 5 nA.

According to an embodiment of the present invention, the cutting in the step (c) may include cutting a portion of the second preliminary specimen located below the protective layer except for a portion thereof, A method of bonding a needle to a layer, and then cutting off a portion that has not been cut.

According to one embodiment of the present invention, the needle is separated from the third preliminary specimen together with the protective layer before the step (d).

According to one embodiment of the present invention, in the step (d), the third preliminary specimen is milled to have a thickness of 50 to 150 nm.

According to the method of the present invention, the internal structure of a film having a thickness of several tens of micrometers or more can be analyzed. The method according to the invention is particularly suitable for analyzing the internal structure of a film comprising an inorganic layer. According to the method of the present invention, since there is no damage to the inorganic layer existing in the film, analysis of the specimen produced by the method of the present invention using TEM can more accurately analyze the structure inside the film.

1 is a flowchart schematically showing steps of a manufacturing method according to the present invention.
2 is a perspective view showing a manufacturing method according to the present invention as a specific model. Specifically, FIG. 2A shows the analytical film and FIG. 2B shows the first preliminary specimen. FIG. 2C shows the manufacturing process of the second preliminary test piece, and FIG. 2D shows the manufacturing process of the third preliminary test piece. In the case of FIG. 2 (d), in order to more specifically show the process of separating the third preliminary specimen, the hatched portion is virtually cut away.
Fig. 3 is an image showing stepwise the manufacturing method according to the embodiment of the present invention. 3 was measured with a Magellan SEM installed in an FEI HELIOS NANOLAB 450F1 device and measured at 3,500 magnifications under the conditions of an accelerating voltage of 5 kV, a current of 0.2 nA and SE mode.
4 is an image of a specimen prepared according to Example 1 and Comparative Example 1 of the present invention analyzed by a transmission electron microscope (TEM). 4A is an image of the specimen prepared in Example 1 at a magnification of 40,000, and FIG. 4B is an image of specimen prepared in Comparative Example 1 at a magnification of 32,000 times.
FIG. 5 is an image of a specimen prepared according to Example 2 and Comparative Example 2 of the present invention analyzed by a transmission electron microscope (TEM). FIG. Specifically, FIG. 5A is an image of a specimen prepared according to Example 2 measured at 1,750 times magnification (2 μm scale bar) and 15,500 times magnification (0.5 μm scale bar) using TITAN G2 ChemiSTEM (FEI) FETEM, 5A is a graph showing the line profile of the component using STEM EDS. 5B is an image of the specimen prepared according to Comparative Example 2 measured at a magnification of 300 times using an H-7650 TEM (HITACHI).

The embodiments provided in accordance with the present invention can be all achieved by the following description. It is to be understood that the following description is of a preferred embodiment of the present invention and that the present invention is not necessarily limited thereto.

The present invention provides a method for preparing a specimen for structural analysis of a film interior. As shown in FIG. 1, the method may include a step (S100) of manufacturing a first preliminary sample using a microtome method, a step (S200) of preparing a second preliminary sample using a focused ion beam method (S200) Separating the analysis point from the analysis point to produce a third preliminary sample (S300), and milling the third preliminary sample to produce a final sample (S400). A method for producing a test piece according to the present invention including the above steps will be described in detail below.

The film to be analyzed is not particularly limited, but the method of producing a test piece according to the present invention can be more effectively applied when the thickness of the film is not less than several tens of micrometers and includes an inorganic layer in the film. According to one embodiment of the present invention, the inorganic layer may be composed of In, InO _x , ZnO, SnO ₂ , NbO _x , SiO _x, or Ag. . The inorganic layer may be located between the organic layers. The inorganic layer can not be analyzed only by the focused ion beam method when the thicknesses of the organic layers located above and below the inorganic layer are several tens of micrometers or more, respectively. In this case, the method according to the present invention can be more preferably applied. According to one embodiment of the present invention, the organic layer may be composed of polyethylene terephthalate (PET), a cyclic olefin polymer (COP), triacetylcellulose (TAC), polyvinyl alcohol (PVA) or polycarbonate .

The film is cut so that the internal structure is exposed on the surface to prepare the first preliminary specimen. Cleavage is carried out by the microtome method. The microtome method used in the present invention uses a glass knife or a diamond knife, and a method commonly used in the related art can be applied as a specific method. Using the microtome method, the film is cut in a direction perpendicular to the layer containing the analysis point at a distance of 1 to 10 m from the analysis point. Since the inorganic layer may be damaged when using the microtome method as described in the background art, the film is cut at a predetermined distance from the analysis point to prevent damage to the inorganic layer at the analysis point. The inorganic layer at a depth of about 1 mu m or less from the surface of the film cut surface may be damaged by the microtome method. Therefore, the cut surface and the analysis point by the microtome method should be separated by 1 탆 or more so that the specimen free from the damage of the inorganic layer can be manufactured at the analysis point. Further, when the cut surface and the analysis point are spaced apart by more than 10 mu m, the film can not be processed to the depth of the analysis point by the following focused ion beam method, and the manufactured specimen does not include the analysis point .

A second preliminary specimen is prepared by separating a portion including the analysis point from the prepared first preliminary specimen. The second preliminary specimen is fabricated using a focused ion beam method. The protective layer is placed on the upper surface of the analysis point in the first preliminary specimen to prevent the damage of the specimen or the cutting of the unnecessary portion by the middle beam processed by the focused ion beam method. Here, the upper surface means a surface cut by the microtome method located at the upper part of the analysis point. The protective layer may be formed by coating on the surface of the first preliminary sample. According to one embodiment of the present invention, the material of the protective layer may be platinum (Pt) or tungsten (W) metal. The protective layer has a rectangular shape in a form that facilitates the production of the final test piece. The protective layer is formed so that the length in the horizontal direction with the film inner layer in the rectangular protective layer is 1 to 3 占 퐉. The length is then the thickness of the final specimen. It may be desirable for the protective layer to have a length that is easy for the final specimen to be manufactured later without damaging the specimen during the formation of the second preliminary specimen. The length in the direction perpendicular to the film inner layer in the rectangular protective layer is not particularly limited. The length may be determined in consideration of the thickness of the layer to be analyzed and the thickness of the film, and generally a protective layer is formed to a length of 10 to 20 mu m. The thickness of the protective layer may preferably be 0.3 to 1 mu m. When the thickness of the protective layer is less than 0.3 탆, the function as a protective layer is deteriorated. If the thickness of the protective layer is more than 1 탆, it may interfere with the focused ion beam processing.

The first preliminary specimen having the protective layer formed thereon is processed by a focused ion beam method. Based on both sides of the protective layer, the first external preliminary specimen is processed by the focused ion beam method. The both sides refer to the side of the protective layer perpendicular to the film inner layer. Processing by the focused ion method proceeds in two steps to minimize damage to the specimen. First, the first preliminary specimen is sliced at a predetermined distance from both sides of the protective layer, and then the first preliminary specimen is polished to both sides of the protective layer. The predetermined distance from the both side surfaces of the protective layer is not particularly limited, and it is possible to select a position where the polishing operation is easy afterwards without damaging the specimen by the slope cutting. The slope cutting is preferably carried out while the work is easy, without damaging the specimen. According to one embodiment of the present invention, the slope cutting is performed under a beam current condition of 9 to 21 nA. Further, the polishing is performed under more relaxed conditions than the slope cutting, and according to one embodiment of the present invention, the polishing is performed with a beam current condition of 2 to 5 nA. The area or volume processed by the slope cutting is not particularly limited as long as it is advantageous to separate the specimen including the analysis point thereafter.

A third preliminary specimen is prepared by separating a portion of the prepared second preliminary specimen located under the protective layer. The portion of the second preliminary specimen located under the protective layer includes the analysis point, and the final specimen is the portion to be manufactured. To separate the sections, cut using a focused ion beam method. The cutting is performed under a beam current condition of 2 to 5 nA. In the case of cutting all the connected portions from the beginning for separation, it is difficult to secure the third preliminary specimen of a minute size, so that cutting and separation are carried out in the following manner. First, the remaining portion except for a portion is cut, a needle is bonded to the protective layer included in the separated portion, and then a portion not cut is further cut. According to the above method, the third preliminary specimen can be secured without difficulty. When cutting for the first time, it may be convenient to cut in a 'C' shape in which one part is connected as shown in FIG. 2D, but it is not necessarily limited thereto. The needle is bonded only to the protective layer, and the material is not particularly limited as long as it is a component that can be easily bonded to the protective layer without a sense of sheathing. Therefore, the needle may be the same material as the protective layer, or it may be composed of other materials that can be in contact with the protective layer. After separating the third preliminary specimen, the needle and protective layer may be separated from the third preliminary specimen.

The prepared third preliminary specimen is milled to a thickness capable of TEM analysis to finally prepare a specimen for TEM analysis. By the above-described method, the third preliminary specimen separated from the second preliminary specimen is fixed to a device such as, for example, a Cu grid for TEM, and milled to have a thickness capable of TEM analysis. Both of the third preliminary specimens are milled, and the final specimen contains the originally set analysis points. According to one embodiment of the present invention, the final specimen has a thickness of 50 to 150 nm.

FIGS. 2A to 2D are views illustrating a series of processes according to the above-described manufacturing method. The analytical film 100 in which the inorganic layer (or the organic-inorganic hybrid layer) 30 is disposed between the first substrate 10 and the second substrate 20 is prepared as shown in FIG. 2A. The analytical film is cut in the direction of the broken line shown in Fig. The first preliminary specimen 200 produced by cutting is placed in such a manner that the cut surface with the hatched portion is on the upper side as shown in FIG. 2B. A method of manufacturing the second preliminary specimen 200 from the first preliminary specimen 200 is performed as shown in FIG. 2C. A protective layer 40 is coated on the upper surface of the first preliminary sample 200 (310). The first preliminary specimen at a position spaced apart from both sides of the protective layer by a predetermined distance is sliced (320). After slope cutting, the second preliminary specimen is prepared by polishing to both sides of the protective layer (330). A method for manufacturing the third preliminary specimen from the second preliminary specimen is performed as shown in FIG. In FIG. 2D, the hatched section is not actually cut, but is a virtual cut surface for showing the process of separating the third preliminary specimen in more detail. In order to separate the analytical point located under the protective layer of the prepared second preliminary sample, the sample is cut into a 'C' shape as indicated by a broken line (410). The needle 50 is attached to the protective layer located at the part to be separated (420). The remaining connected portions are cut and separated to produce a third preliminary specimen (430). In the third preliminary specimen, the protective layer and the needle are removed and milled to prepare the final specimen. The details of the above process are based on the above description.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the present invention is not limited thereto.

Example

Example  Preparation of Specimen According to the Present Invention of a Film Containing 1: In Thin Film

In order to analyze the internal structure of the film, a film having a structure of PET substrate (50 탆 or more) / primer layer / In thin film (several tens of nm) / adhesive layer (20 탆 or more) was prepared. One point in the thin film layer of the film was set as an analysis point, and a position 5 mu m in the horizontal direction was cut from the analysis point in a vertical direction using a microtome apparatus. At this time, the microtome device was a LEICA EM UC7 model. The surface cut by the microtome apparatus was placed at the top, and a focused ion beam apparatus was used. For the focused ion beam device, HELIOS NanoLab 450F1 from FEI was used. Prior to processing through the focused ion beam device, a Pt protective layer of size 15 占 2 占 0 占 퐉 (width 占 length 占 height) was formed on the upper surface of the specimen at a beam current condition of 0.23 nA. After the formation of the protective layer, the specimen was slit-cut at a beam current condition of 9 nA spaced a predetermined distance from both sides of the protective layer. The slope cutting was performed on both sides with a size of 20 mu m x 15 mu m x 10 mu m (width x height x height). After slope cutting, the specimens were polished to reach both ends of the Pt protective layer at a beam current condition of 2.5 nA. Slice cutting and the lower end of the un-polished protective layer were cut into a " C " shape with a beam current condition of 2.5 nA to separate the specimen containing the analysis point. The needle was bonded to the protective layer using a Pt depo (beam current condition of 80 pA), with the part connected without completely cutting the entirety. Thereafter, the remaining portion was completely cut, and the specimen was separated. The separated specimens were placed on a Cu grid for TEM, and the final specimens were prepared by milling specimens with a thickness of 2 μm to a thickness of about 100 nm.

Comparative Example  Prior Art of Films Containing 1: In Thin Films ( microtome  Use)

As in Example 1, a film having a structure of PET substrate (50 탆 or more) / primer layer / In thin film (several tens of nm) / adhesive layer (20 탆 or more) was prepared. A point in the thin film layer of the film was set as an analysis point, and a final sample was prepared by using a microtome device which was used in the related art to analyze the analysis point.

Example  1 and Comparative Example  Analysis of specimen according to 1

The final specimens according to Example 1 and Comparative Example 1 were analyzed via transmission electron microscopy (TEM), respectively. The image analyzed through the transmission electron microscope is shown in FIG. 4A (Example 1) and FIG. 4B (Comparative Example 1).

According to FIG. 4A, it can be seen that the final test piece according to Example 1 exhibits an even thickness of the inorganic layer with a thickness of about 54 nm without breakage of the inorganic layer. On the other hand, according to FIG. 4B, the final specimen according to Comparative Example 1 has an intermediate intermediate broken portion in the inorganic layer, and the thickness of the inorganic layer is uneven to about 44 to 63 nm.

Further, although not shown as a comparative example, in the case of a focused ion beam apparatus (FIB), it is not possible to prepare a specimen for analyzing an inorganic layer existing in a depth of several tens of micrometers or more.

Example  2: PVA  Preparation of specimen according to the present invention of a polarizing plate

To analyze the internal structure of the polarizing plate, a polarizing plate having a structure of TAC (several tens of micrometers or more) / adhesive layer (several hundreds of nm) / PVA (several tens of micrometers) / adhesive layer (several hundreds of nm) / TAC (several tens of micrometers or more) Specimens were prepared in the same manner as in Example 1, except for the materials to be manufactured.

Comparative Example  2: PVA  The conventional technology of the polarizing plate microtome  Use)

A polarizing plate having a structure of TAC (several tens of 탆 or more) / adhesive layer (several hundreds of nm) / PVA (several tens of 탆) / adhesive layer (several hundreds of nm) / TAC (several tens of 탆 or more) was prepared. Specimens were prepared in the same manner as in Comparative Example 1, except for the materials to be manufactured.

Example  2 and Comparative Example  Analysis of specimen according to 2

The final specimens according to Example 2 and Comparative Example 2 were each analyzed through a transmission electron microscope (TEM). The image analyzed through the transmission electron microscope is shown in FIG. 5A (Example 2) and FIG. 5B (Comparative Example 2).

In the case of using a conventional microtome as in Comparative Example 2, there is a process of making a TEM specimen and floating it on a Cu mesh. In this case, the weak PVA is damaged, and the problem of peeling of the specimen as shown in FIG. Occurs. Therefore, in order to analyze the thickness and the composition of the adhesive layer, it is necessary to process the TEM sample of the adhesive layer without damaging the PVA layer. For this purpose, the thickness and the composition of the adhesive layer were analyzed as shown in FIG. 5A when the TEM cross section sample was prepared and analyzed through the FIB in the microtome section. According to the graph of FIG. 5A, Si, C and O were measured as components of the adhesive layer, and SiO _x was particularly added as an inorganic component.

Taking all the above into consideration, the method of preparing a sample according to the present invention enables accurate layer structure analysis at the nanometer level in analyzing the internal structure of a film having a certain thickness or more, in which an inorganic layer exists.

It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

10: First substrate
20: second substrate
30: inorganic or organic-inorganic hybrid layer
40: Protective layer
50: Needle
100: Analysis film
200: First preliminary specimen
310: First protective sample coated with protective layer
320: slope-cut first preliminary specimen
330: Second preliminary specimen prepared after polishing
410: partially cut second preliminary specimen
420: second preliminary specimen to which the needles are bonded
430: the third preliminary specimen is separated from the second preliminary specimen

Claims (10)

(a) preparing a first preliminary specimen by cutting the film by a microtome method so that the internal structure of the film is revealed;
(b) placing a protective layer on the upper surface of the analysis point in the first preliminary specimen and fabricating an outer first preliminary specimen using a focused ion beam method based on both sides of the protective layer to produce a second preliminary specimen step;
(c) preparing a third preliminary specimen by cutting with a focused ion beam method to separate a portion of the second preliminary specimen including an analysis point located under the protective layer; And
(d) milling the third preliminary specimen so as to analyze the analysis point at a thickness capable of TEM analysis to prepare a specimen for TEM analysis,
Wherein the film comprises an inorganic layer in the interior of the film. The method according to claim 1,
Wherein the microtome method comprises cutting a film using a glass knife or a diamond knife in the step (a). The method according to claim 1,
Wherein the cutting is performed in a direction perpendicular to the layer including the analysis point at a point 1 to 10 占 퐉 apart from the analysis point in the step (a). The method according to claim 1,
In the step (b), the protective layer may be formed of a platinum (Pt) or tungsten (W) coating, and the coating is formed to have a length of 1 to 3 μm in the horizontal direction with the inner layer of the film. A method for manufacturing a specimen for internal structure analysis. The method according to claim 1,
In the step (b), the processing by the focused ion beam method is performed by slope cutting the first preliminary specimen with a predetermined distance from both sides of the protective layer, and then applying a first preliminary specimen to both sides of the protective layer Wherein the film is processed by polishing the film. The method of claim 5,
Wherein said slope cutting is performed at a beam current condition of 9 to 21 nA. ≪ RTI ID = 0.0 > 8. < / RTI > The method of claim 5,
Wherein the polishing is performed at a beam current condition of 2 to 5 nA. ≪ RTI ID = 0.0 > 8. < / RTI > The method according to claim 1,
The cutting in the step (c) may be performed by cutting a portion of the second preliminary specimen except the part to be located below the protective layer, and attaching a needle to the protective layer included in the part to be separated And then cutting the uncut portion of the film. ≪ RTI ID = 0.0 > 11. < / RTI > The method of claim 8,
Wherein the needle is separated from the third preform with the protective layer before step (d). ≪ Desc / Clms Page number 20 > The method according to claim 1,
Wherein the third preliminary specimen is milled to have a thickness of 50 to 150 nm in the step (d).

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