Method for improving sample analysis effect of transmission electron microscope

Abstract

The invention provides a method for improving the analysis effect of a transmission electron microscope sample, and the method comprises the steps: providing a sample structure which comprises a substrate, a target layer formed on the surface of the substrate and a protection layer formed on the surface of the target layer from bottom to top, and the target layer is provided with a target region for analysis; etching the target layer from the side surface of the sample structure to form mark holes in the two sides of the target region, wherein the mark holes penetrate through the front side and the rear side of the sample structure; forming a filler in the mark hole to obtain a graphic mark, wherein the contrast of the filler under the transmission electron microscope is different from the contrast of the substrate, the target layer and the protective layer; wherein each mark pattern comprises an extension part along a first direction and an extension part along a second direction, the first direction is the up-down direction of the sample structure, and the second direction is the left-right direction of the sample structure. According to the invention, the problem of poor EDS analysis effect in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a method for improving the analysis effect of a transmission electron microscope sample. Background Art

[0002] In the semiconductor industry, transmission electron microscope (TEM) is an indispensable analytical device for semiconductor failure analysis. EDS (Energy Dispersive Spectroscopy) is the main means of TEM component analysis and is used very frequently.

[0003] However, thermal drift will occur during the EDS analysis due to the irradiation of the molecular beam. In order to offset thermal drift, the industry has added a drift correction function to the EDS operating software. The use process of this function is to first capture the image before starting to collect the EDS signal, then turn on the drift calibration to collect the EDS signal, and finally complete the EDS signal collection. The drift correction in this process is achieved by comparing the image captured before collecting the signal with the real-time image during the collection process. However, for layered samples without special graphics, the software cannot distinguish the changes in the images before and after, and thus cannot effectively implement the drift correction function. Therefore, the obtained EDS analysis effect is poor. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a method for improving the analysis effect of transmission electron microscopy samples, so as to solve the problem of poor analysis effect of the existing EDS.

[0005] To achieve the above-mentioned object and other related objects, the present invention provides a method for improving the analysis effect of a transmission electron microscope sample, the method comprising:

[0006] A sample structure is provided, which comprises, from bottom to top, a substrate, a target layer formed on the surface of the substrate, and a protective layer formed on the surface of the target layer, wherein the target layer has a target area for analysis;

[0007] Etching the target layer from the side of the sample structure to form marking holes on both sides of the target area, and the marking holes penetrate the front and back sides of the sample structure;

[0008] Forming a filler in the marking hole to obtain a graphic mark, and the contrast of the filler under a transmission electron microscope is different from the contrast of the substrate, the target layer and the protective layer;

[0009] The marking pattern includes an extension portion extending along a first direction and a second direction, and the first direction is a vertical direction of the sample structure, and the second direction is a horizontal direction of the sample structure.

[0010] Optionally, the cross-section of the graphic mark is triangular, and the top angle of the triangle is arranged toward the target area and serves as an extension in the first direction, and the bottom angle serves as an extension in the second direction.

[0011] Optionally, the graphic mark further includes an extension portion, which is rectangular and combined with the triangle to form an arrow shape.

[0012] Optionally, the cross-section of the graphic mark is L-shaped, and the horizontal portion of the L-shaped graphic mark is located in the first direction, and the vertical portion thereof is located in the second direction.

[0013] Optionally, the cross section of the graphic mark is in a cross shape, a horizontal portion of the cross-shaped graphic mark is located in a first direction, and a vertical portion of the cross-shaped graphic mark is located in a second direction.

[0014] Optionally, the graphic marks are symmetrically arranged on both sides of the target area.

[0015] Optionally, the graphic mark is formed entirely or partially in the target layer.

[0016] Optionally, when forming the graphic mark, the filler formed in the mark hole includes metal tungsten or metal platinum.

[0017] Optionally, the target layer includes at least one layer.

[0018] Optionally, the target layer includes an oxide layer and / or a nitride layer.

[0019] Optionally, the protection layer includes a TEOS layer or a carbon layer.

[0020] Optionally, the substrate comprises a silicon substrate.

[0021] Optionally, the thickness of the front and rear sides of the sample structure is between 190 nm and 210 nm.

[0022] Optionally, after forming the graphic mark, the method further comprises the step of thinning the sample structure.

[0023] Optionally, the thickness of the front and rear sides of the sample structure after the thinning process is 25nm to 35nm.

[0024] As described above, the method of improving the analysis effect of transmission electron microscope samples of the present invention can be used for sample structures without special patterns. By forming graphic marks on both sides of the target area, when preparing transmission electron microscope samples using FIB, an image drift correction reference is obtained during the EDS analysis process, thereby effectively realizing the drift correction function and achieving the purpose of improving the EDS analysis effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Shown is a schematic diagram of the cross-sectional structure of the sample structure of the present invention.

[0026] Figure 2 Display as Figure 1 FIB image of the sample structure shown.

[0027] Figure 3 It is a schematic diagram of the cross-sectional structure after marking holes are formed on the front and back sides of the sample structure of the present invention.

[0028] Figure 4 Display as Figure 3 FIB image of the sample structure shown.

[0029] Figure 5 It is a schematic diagram showing the cross-sectional structure of the sample structure after the graphic mark is formed according to the present invention.

[0030] Figure 6 Display as Figure 5 FIB image of the sample structure shown.

[0031] Figure 7 Shown is a schematic diagram of the cross-sectional structure of the thinned sample structure of the present invention.

[0032] Figure 8 Display as Figure 7 FIB diagram of the structure shown.

[0033] Figure 9a The TEM image of the existing sample structure is shown, where the part in the red box represents the target layer.

[0034] Figure 9b Show as pair Figure 9a The figure shown is the effect diagram obtained by EDS analysis.

[0035] Fig.10a Shown are TEM images of the sample structure of the present invention at different magnifications (28.5K, 450K), wherein the portion in the red frame represents the target layer.

[0036] Fig.10b The result of EDS analysis of Figure 10a is shown.

[0037] Fig.11a A schematic diagram showing a graphical marker with a triangular cross section.

[0038] Fig.11b A schematic diagram showing a cross section in the shape of an arrow.

[0039] Fig.11c A schematic diagram showing a graphical mark having an L-shaped cross section.

[0040] Fig.11d A schematic diagram showing a cross-shaped cross section.

[0041] Fig.12 Shown is a flow chart of the method for improving the analysis effect of transmission electron microscope samples according to the present invention. DETAILED DESCRIPTION

[0042] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0043] See also Figures 1 to 12 It should be noted that the illustrations provided in this embodiment are only schematic illustrations of the basic concept of the present invention. Although the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation, the form, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the component layout may also be more complicated.

[0044] like Fig.12 As shown, this embodiment provides a method for improving the analysis effect of a transmission electron microscope sample, the method comprising:

[0045] A sample structure is provided, which comprises, from bottom to top, a substrate, a target layer formed on the surface of the substrate, and a protective layer formed on the surface of the target layer, wherein the target layer has a target area for analysis;

[0046] Etching the target layer from the side of the sample structure to form marking holes on both sides of the target area, and the marking holes penetrate the front and back sides of the sample structure;

[0047] Forming a filler in the marking hole to obtain a graphic mark, and the contrast of the filler under a transmission electron microscope is different from the contrast of the substrate, the target layer and the protective layer;

[0048] The marking pattern includes an extension portion extending along a first direction and a second direction, and the first direction is a vertical direction of the sample structure, and the second direction is a horizontal direction of the sample structure.

[0049] In this embodiment, the target area of ​​the sample structure provided has no special pattern and is not easily distinguished by the EDS operating software, so it is necessary to form the graphic mark. It should be noted that Figure 1In the figure, the direction indicated by X represents the left-right direction of the sample structure, the direction indicated by Y represents the front and back sides of the sample structure, and the direction indicated by Z represents the up and down direction of the sample structure.

[0050] Specifically, the thickness of the front and rear sides of the sample structure ranges from 190 nm to 210 nm.

[0051] In this embodiment, the thickness of the front and rear sides of the sample structure is 200nm. By thinning the sample structure to a thickness of 200nm, it is easy to operate when forming the marking hole. There will be no situation where the marking hole cannot be penetrated due to the thick thickness of the front and rear sides of the sample structure, or the sample structure is damaged in the process of forming the marking hole.

[0052] Specifically, the substrate includes a silicon substrate.

[0053] Specifically, the target layer includes at least one layer.

[0054] More specifically, the target layer includes an oxide layer and / or a nitride layer. In this embodiment, when the target layer includes both an oxide layer and a nitride layer, the target layer is a layered structure.

[0055] Specifically, the protection layer includes a TEOS layer or a carbon layer.

[0056] Specifically, the graphic marks are symmetrically arranged on both sides of the target area.

[0057] Specifically, the graphic mark is formed entirely or partially in the target layer.

[0058] Specifically, when forming the graphic mark, the filler formed in the mark hole includes metal tungsten or metal platinum.

[0059] Specifically, the cross section of the graphic mark is triangular, and the top angle of the triangle is arranged toward the target area and serves as an extension portion in the first direction, and the bottom angle serves as an extension portion in the second direction.

[0060] like Fig.11a As shown, in this embodiment, the cross section is the surface presented when the graphic mark is cut from top to bottom. In this embodiment, the triangle presented by the cross section of the graphic mark is an isosceles triangle, the vertex of the isosceles triangle serves as the extension in the first direction, and the two bottom angles thereof serve as the extension in the second direction. Moreover, in this embodiment, the bottom length of the isosceles triangle is 40nm and the height is 20nm.

[0061] Specifically, the graphic mark further includes an extension portion, which is rectangular and combined with the triangle to form an arrow shape.

[0062] like Fig.11b As shown, in this embodiment, the length of the rectangular extension portion is 50 nm and the width is 20 nm.

[0063] Specifically, the cross section of the graphic mark is L-shaped, the horizontal portion of the L-shaped graphic mark is located in the first direction, and the vertical portion of the L-shaped graphic mark is located in the second direction.

[0064] like Fig.11c As shown, in this embodiment, the horizontal portion of the L-shaped graphic mark serves as an extension in the first direction, and the vertical portion serves as an extension in the second direction.

[0065] Specifically, the cross section of the graphic mark is in a cross shape, the horizontal portion of the cross-shaped graphic mark is located in the first direction, and the vertical portion of the cross-shaped graphic mark is located in the second direction.

[0066] like Fig.11d As shown, in this embodiment, the horizontal portion of the cross-shaped graphic mark serves as an extension portion in the first direction, and the vertical portion serves as an extension portion in the second direction.

[0067] Specifically, after forming the graphic mark, the method further comprises the step of thinning the sample structure.

[0068] More specifically, the thickness of the front and rear sides of the sample structure after the thinning process is 25 nm to 35 nm.

[0069] In this embodiment, the thickness of the front and rear sides of the sample structure after thinning is 30 nm to facilitate EDS analysis.

[0070] Figure 9a TEM image showing the existing sample structure, Figure 9b Shows the Figure 9a The figure shown is the effect diagram obtained by EDS analysis; Fig.10a TEM image showing the structure of the sample of the present invention, Fig.10b The effect diagram of EDS analysis of the graph shown in 10a is shown. It can be seen from the figure that the EDS analysis effect is significantly improved.

[0071] In summary, the method for improving the analysis effect of transmission electron microscope samples of the present invention can form graphic marks on both sides of the target area for sample structures without special patterns, so that when preparing transmission electron microscope samples with FIB, an image drift correction reference object is obtained during EDS analysis, thereby effectively realizing the drift correction function and achieving the purpose of improving the EDS analysis effect. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0072] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for improving the analysis effect of transmission electron microscope samples, characterized in that: The method comprises: A sample structure is provided, which comprises, from bottom to top, a substrate, a target layer formed on the surface of the substrate, and a protective layer formed on the surface of the target layer, wherein the target layer has a target area for analysis; Etching the target layer from the side of the sample structure to form marking holes on both sides of the target area, and the marking holes penetrate the front and back sides of the sample structure; Forming a filler in the marking hole to obtain a graphic mark, and the contrast of the filler under a transmission electron microscope is different from the contrast of the substrate, the target layer and the protective layer; The marking pattern includes an extension portion extending along a first direction and a second direction, and the first direction is a vertical direction of the sample structure, and the second direction is a horizontal direction of the sample structure.

2. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The cross section of the graphic mark is triangular, and the top angle of the triangle is arranged toward the target area and serves as an extension in the first direction, and the bottom angle serves as an extension in the second direction.

3. The method for improving the analysis effect of transmission electron microscope samples according to claim 2, characterized in that: The graphic mark also includes an extension portion, which is rectangular and combined with the triangle to form an arrow shape.

4. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The cross section of the graphic mark is L-shaped, the horizontal portion of the L-shaped graphic mark is located in the first direction, and the vertical portion of the L-shaped graphic mark is located in the second direction.

5. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The cross section of the graphic mark is in a cross shape, the horizontal portion of the cross-shaped graphic mark is located in the first direction, and the vertical portion of the cross-shaped graphic mark is located in the second direction.

6. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The graphic marks are symmetrically arranged on both sides of the target area.

7. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The graphic mark is formed entirely or partially in the target layer.

8. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: When forming the graphic mark, the filler formed in the mark hole includes metal tungsten or metal platinum.

9. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The target layer includes at least one layer.

10. The method for improving the analysis effect of transmission electron microscope samples according to claim 9, characterized in that: The target layer includes an oxide layer and / or a nitride layer.

11. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The protection layer includes a TEOS layer or a carbon layer.

12. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The substrate includes a silicon substrate.

13. The method for improving the analysis effect of transmission electron microscope samples according to claim 1, characterized in that: The thickness of the sample structure at the front and rear sides ranges from 190 nm to 210 nm.

14. The method for improving the analysis effect of a transmission electron microscope sample according to claim 1, characterized in that: After forming the graphic mark, the method further comprises the step of thinning the sample structure.

15. The method for improving the analysis effect of transmission electron microscope samples according to claim 14, characterized in that: The thickness of the front and rear sides of the sample structure after the thinning process is 25nm to 35nm.

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