Angle resolution XPS test method

Abstract

The invention discloses an angular resolution XPS test method. The method comprises the following steps: fixing a to-be-tested sample on a sample support; covering the to-be-tested sample with a conductive film with a hollow-out pattern, and fixing the conductive film to enable the hollow-out pattern of the conductive film to be aligned with the central test position of the to-be-tested sample; placing the to-be-tested sample covered with the conductive film in an XPS analyzer, and positioning the central test position of the to-be-tested sample through imaging equipment; and determining a test position by taking the hollow pattern of the conductive film as a mark at different test angles, and carrying out angle resolution XPS test on the to-be-tested sample. According to the angle resolution XPS test method provided by the invention, the surface of the sample to be tested is covered with the conductive film with the hollow-out pattern, and the hollow-out pattern on the conductive film is used as a mark, so that when the angle of the sample relative to the analyzer is changed, the accuracy of the included angle between the sample and the analyzer is ensured, and the accuracy of the angle resolution XPS test is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectron energy spectrum analysis, and particularly relates to an angle-resolved XPS testing method. Background Art

[0002] X-ray photoelectron spectroscopy (XPS) is a highly effective surface analysis method widely used in fields such as materials science, physical chemistry, and biomedicine. XPS uses X-rays to illuminate the sample surface, inducing the emission of photoelectrons. By analyzing the energy distribution of these photoelectrons, important information such as the type, chemical state, and relative content of elements on the sample surface can be obtained. Traditional XPS technology has a surface detection depth of approximately 10 nanometers, making it an ideal tool for analyzing the surface properties of materials such as ultrathin films and surface-modified layers.

[0003] With advances in science and technology, the demand for surface analysis of materials has become increasingly refined, especially for samples with complex surface morphologies, such as spherical particles. To obtain detailed chemical information on the surfaces of such samples, angle-resolved XPS (ARXPS) has emerged. By varying the sample's orientation relative to the analyzer and adjusting the depth of detection, ARXPS enables hierarchical analysis of the chemical composition of the sample's surface and near-surface regions.

[0004] However, existing angle-resolved XPS testing places strict demands on sample flatness. This is because the angle between the sample surface and the analyzer must be precisely controlled to ensure accurate measurement data. For samples with uneven surfaces, the angle between the sample and the analyzer can vary, making angle-resolved testing extremely difficult on conventional XPS equipment.

[0005] Therefore, it is necessary to provide a new solution to the above technical problems. Summary of the Invention

[0006] The object of the present invention is to provide an angle-resolved XPS testing method, which can solve the problem that it is difficult to determine the angle between a sample with an uneven surface and an analyzer during angle-resolved XPS testing.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides an angle-resolved XPS testing method, comprising:

[0009] The sample to be tested is fixed on the sample holder; a conductive film with a hollow pattern is covered on the sample to be tested, and the conductive film is fixed so that the hollow pattern of the conductive film is aligned with the center test position of the sample to be tested; the sample to be tested covered with the conductive film is placed in the XPS analyzer, and the center test position of the sample to be tested is located using an imaging device; at different test angles, the test position is determined using the hollow pattern of the conductive film as a mark, and angle-resolved XPS testing is performed on the sample to be tested.

[0010] In one or more embodiments, the sample to be tested is spherical.

[0011] In one or more embodiments, the diameter of the sample to be tested is 100 to 5000 μm.

[0012] In one or more embodiments, the sample to be tested is fixed on the sample holder by bonding with double-sided conductive copper adhesive.

[0013] In one or more embodiments, the conductive film is a metal foil or a conductive polymer film.

[0014] In one or more embodiments, the hollow pattern is a diamond shape.

[0015] In one or more embodiments, the size of the short diagonal line of the hollow pattern is 1.5 to 2.5 times the size of the X-ray spot of the XPS analyzer.

[0016] In one or more embodiments, the imaging device is an SXI imager.

[0017] In one or more embodiments, the XPS analyzer is a PHI 5000 Versaprobe III analyzer.

[0018] In one or more embodiments, the test angle is between 10° and 90°.

[0019] Compared with the prior art, the angle-resolved XPS testing method provided by the present invention covers the surface of the sample to be tested with a conductive film having a hollow pattern, uses the hollow pattern on the conductive film as a mark, and directly aligns it with the central test position of the sample, thereby ensuring that the X-ray beam of the analyzer can accurately irradiate a specific area of ​​the sample; the test position is determined by using the hollow pattern of the conductive film as a mark, and when the angle of the sample relative to the analyzer is changed, the accuracy of the angle between the sample and the analyzer is ensured, thereby improving the accuracy of the angle-resolved XPS test. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments described in the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0021] Figure 1 Flowchart of the angle-resolved XPS testing method according to one embodiment of the present invention;

[0022] Figure 2 A schematic diagram of a conductive film covering a sample to be tested in one embodiment of the present invention;

[0023] Figure 3 This is the imaging of the sample to be tested in Example 1 of the present invention when it is not covered with the aluminum foil paper with diamond-shaped hollows;

[0024] Figure 4 This is the imaging of the sample to be tested when it is covered with aluminum foil with diamond-shaped hollows in Example 1 of the present invention;

[0025] Figure 5 : This is the angle-resolved XPS spectrum of the C element of the sample to be tested in Example 1 of the present invention;

[0026] Figure 6 : This is the N element angle-resolved XPS spectrum of the sample to be tested in Example 1 of the present invention;

[0027] Figure 7 This is the angle-resolved XPS spectrum of the O element of the sample to be tested in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] Unless otherwise indicated, all numbers used in the specification and claims to represent feature sizes, quantities, and physical properties should be understood as being modified in all cases by the term "about". Therefore, unless otherwise indicated, the numerical parameters listed in the above specification and the appended claims are approximate values, and those skilled in the art will be able to appropriately change these approximate values ​​by utilizing the teachings disclosed herein to seek to obtain the desired properties. The use of numerical ranges expressed as endpoints includes all numbers within the range and any range within the range, for example, 1 to 5 includes 1, 1.2, 1.4, 1.55, 2, 2.75, 3, 3.80, 4 and 5, etc.

[0030] In modern materials science and surface chemistry research, X-ray photoelectron spectroscopy (XPS) technology is an important tool for analyzing the surface composition and chemical state of materials. In particular, angle-resolved XPS (ARXPS) technology can provide deeply resolved chemical information about the surface of the material and its near-surface area by changing the angle between the sample and the analyzer, providing extremely important information for understanding the surface reaction mechanism of the material and optimizing the surface treatment process of the material. However, in traditional angle-resolved XPS testing methods, the test sample is usually required to have a relatively flat surface. This limitation significantly reduces the flexibility of angle-resolved XPS technology in practical applications, especially for samples that naturally have non-flat surfaces, such as spherical particles, powders and other materials. The accurate analysis of their surface characteristics has become a major technical challenge.

[0031] Faced with this limitation of existing technology, the inventors conducted in-depth analysis and research. Through observation and experimentation, they discovered that the greatest challenge in performing angle-resolved XPS on samples with uneven surfaces lies in the inability to precisely control and repeat the sample's specific position and angle relative to the XPS analyzer, resulting in the inability to obtain accurate chemical state data. Furthermore, traditional methods often require destructive surface treatment when processing such samples, which not only alters the sample's original surface state but also potentially affects its intrinsic properties.

[0032] In view of this, the present invention provides a new angle-resolved XPS testing method to solve the above problems. The core idea of ​​this method is to use a layer of conductive film with a specific hollow pattern to cover the sample to be tested. This design innovatively combines the traditional XPS testing method with a new sample positioning technology, which not only maintains the original state of the sample, but also realizes precise angle control and positioning of samples with non-flat surfaces. In this way, even samples with complex shapes such as spheres can accurately locate the test position in XPS analysis, thereby performing accurate chemical state analysis at different angles.

[0033] Please refer to Figure 1FIG. 1 is a flow chart of an angle-resolved XPS testing method according to an embodiment of the present invention.

[0034] The angle-resolved XPS test method specifically includes the following steps:

[0035] S101: Fix the sample to be tested on the sample holder.

[0036] It's important to note that in angle-resolved XPS testing, ensuring the stability of the sample throughout the entire test is a prerequisite for obtaining accurate and reliable test data. This is achieved by securing the sample to the sample holder. Sample stability not only affects test accuracy but also directly impacts the ability to perform precise and repeatable measurements at different angles.

[0037] The method for securing the sample to be tested can be selected based on actual needs. For example, for small or lightweight samples, double-sided conductive tape can be applied directly to the sample holder; this method is simple and convenient while providing good conductivity. For larger or irregularly shaped samples, a mechanical clamp can be used for securing; this method can accommodate samples of various shapes and sizes, maintaining sample stability during testing. For very smooth or fragile samples, a vacuum system can be used to secure the sample to the sample holder; this method provides a very stable fixation method without causing physical damage to the sample.

[0038] In an exemplary embodiment, the sample to be measured is spherical, with a diameter of 100 to 5000 μm. This diameter range is chosen based on the analytical depth and spot size of the XPS technique. XPS typically probes to a depth of less than 10 nm, while the spot size can range from micrometers to millimeters. Within this diameter range, the surface of the spherical sample is large enough to accommodate the XPS spot while maintaining the intensity and resolution of the photoelectron signal.

[0039] Specifically, the sample to be tested is secured to the sample holder using double-sided conductive copper adhesive. During XPS testing, the sample must be in a good conductive state to prevent charge accumulation that could affect the accuracy of the test results. Double-sided conductive copper adhesive not only secures the sample but also ensures a good electrical path between the sample and the sample holder, helping to eliminate or reduce charge accumulation.

[0040] Maintaining sample stability during XPS scanning or angle changes is crucial for achieving repeatable and accurate test results. Double-sided conductive copper adhesive, with its strong adhesion, effectively secures samples of various sizes and shapes, including tiny spherical specimens, ensuring their stable position throughout the test. Furthermore, double-sided conductive copper adhesive is easy to use and can quickly secure samples to the specimen holder without the need for complex mechanical fixtures or other equipment. This simplifies test preparation and improves work efficiency.

[0041] S102: Covering the sample to be tested with a conductive film having a hollow pattern, and fixing the conductive film so that the hollow pattern of the conductive film is aligned with the central test position of the sample to be tested.

[0042] It should be noted that covering the sample with a conductive film with a hollow pattern creates a visual marker that aligns with the center of the sample's test location. The hollow pattern serves as a physical marker, precisely indicating the center of the sample surface or the location of a specific test area. The conductive film not only secures the sample but also provides a reference point for accurately locating the test area during XPS analysis.

[0043] like Figure 2 As shown, the conductive film can be gently fixed on the sample using tape or transparent tape, without covering the hollow part, and ensuring that the conductive film is flat and the hollow pattern is aligned.

[0044] In an exemplary embodiment, the conductive film can be a metal foil, a conductive polymer film, or the like, which has good electrical conductivity and a certain mechanical strength for ease of handling. Both metal foil and conductive polymer films have excellent electrical conductivity and can effectively conduct away the charge generated during the XPS test, thereby ensuring the accuracy and reliability of the data. The conductive film is preferably aluminum foil.

[0045] Aluminum foil has sufficient mechanical strength and flexibility to adhere tightly to the sample surface without damaging it, and can withstand the slight mechanical stress that may occur during XPS testing, such as sample rotation or tilting. Furthermore, aluminum foil exhibits excellent chemical stability under the vacuum and irradiation conditions involved in XPS testing, and does not react with the sample or generate interfering signals during the test.

[0046] In one exemplary embodiment, the hollow pattern is preferably a diamond shape, with the short diagonal dimension of the pattern being 1.5 to 2.5 times the size of the XPS analyzer's X-ray spot. This diamond pattern provides an efficient way to precisely locate the area to be tested while ensuring uniform X-ray beam coverage across the entire test area. Compared to other shapes, the diamond shape's geometric properties make it easier to maintain effective alignment with the X-ray spot when rotating the sample to change the test angle.

[0047] The diamond pattern, due to its symmetry and unique geometry, provides clear directional identification at various test angles. When rotated, the diamond pattern maintains minimal change in its projected shape and area, helping to maintain a consistent test area at different angles, thereby ensuring accurate and repeatable test data.

[0048] The short diagonal line of the hollow pattern (diamond) is set to 1.5 to 2.5 times the X-ray spot size to ensure that the collected signal comes not only from the directly irradiated area, but also includes the surrounding microscopic areas. This can enhance the representativeness and reliability of the signal without sacrificing resolution. There are often microscopic inhomogeneities on the sample surface. By expanding the test area to 1.5 to 2.5 times the spot size, the sample surface can be analyzed more comprehensively, reducing the impact of local heterogeneity on the results, and improving the overall accuracy and reliability of the test.

[0049] In other embodiments, the hollow pattern may also be designed into other shapes, such as rectangle, square, oval, etc.

[0050] S103: placing the sample to be tested covered with the conductive film in an XPS analyzer, and locating the central test position of the sample to be tested by an imaging device.

[0051] First, secure the sample covered with a conductive film to the sample holder within the XPS analyzer's sample chamber. Ensure the sample is stable to prevent movement during the test. Use the analyzer's built-in imaging device (either a CCD camera or X-ray stimulated secondary electron imaging) to center the hollow pattern. In some cases, it may be necessary to adjust the sample's position or the imaging device's focus to ensure the clearest possible image.

[0052] Based on the view provided by the imaging device, adjust the sample position until the center of the hollow pattern is perfectly aligned with the expected illumination point of the X-ray beam. This process may require fine-tuning the position of the sample stage.

[0053] The imaging device is preferably an SXI imager, and the XPS analyzer can be a PHI 5000 Versaprobe III analyzer. SXI (X-ray Excitation Secondary Electron Imaging) is preferred for its high resolution and sensitivity. During XPS testing, the sample surface and the hollow pattern of the conductive film must be clearly observed to ensure precise positioning. SXI provides high-quality images, which facilitates precise positioning of the test area.

[0054] S104: At different test angles, the test position is determined using the hollow pattern of the conductive film as a marker, and angle-resolved XPS testing is performed on the sample to be tested.

[0055] By using pre-set hollow patterns on the conductive film as physical markers and adjusting the sample stage angle, precise XPS analysis of specific sample areas at different angles is possible. In angle-resolved XPS testing, varying the angle between the sample and the analyzer allows for the detection of chemical information at varying depths on the sample surface. Using the hollow patterns on the conductive film as markers ensures that the test position remains accurately aligned with the specific sample area, even when the angle is changed.

[0056] The specific testing process involves using the XPS analyzer's sample stage to precisely control the sample's tilt angle relative to the X-ray source. Software control or manual adjustment allows the sample to be tested at a predetermined angle. The XPS analyzer's built-in imaging device, such as the SXI imaging system, can be used to align the sample with the cutout pattern on the conductive film, ensuring that the test beam accurately illuminates the marked area. At each predetermined angle, the photoelectron signal escaping from the cutout pattern is collected and analyzed for energy spectrum.

[0057] The present invention will be further described below with reference to specific embodiments.

[0058] Example 1

[0059] The sample to be tested is spherical silica microspheres with a diameter of 1 mm and a surface modified with an ultra-thin polymer film of about 3 nm thick.

[0060] The sample to be tested is fixed on the sample holder by bonding with conductive copper glue, and the surface of the sample to be tested is covered with aluminum foil with diamond-shaped hollows, where the short diagonal size of the diamond-shaped hollows is about 200 microns.

[0061] The sample to be tested was transferred to the sample stage of the XPS analyzer (PHI 5000 Versaprobe III analyzer), and the center test position of the sample to be tested was located by SXI imaging. Figure 3 This is the image of the sample to be tested when it is not covered with the aluminum foil with diamond-shaped hollows. Figure 4 The image of the sample to be tested covered with aluminum foil with diamond-shaped hollows.

[0062] The sample stage was tilted and the diamond position imaging was still used for positioning at different angles, and finally the angular resolved XPS test results of the sample at angles of 15°, 30°, 40°, 60°, 70°, and 90° were obtained.

[0063] Please refer to Figures 5 to 7 As shown in the figure, comparing the C, O, and N spectra of the sample under test at different angles reveals that at small angles, C and N (the main components of the polymer film) dominate. As the angle increases, the detection depth deepens, and Si and O (the main components of the silica microspheres) increase relatively. The intensity of O is used to calculate the film thickness. Using the Beer-Lambert equation to calculate the film thickness, the polymer film thickness is approximately 3nm, which is consistent with the actual value.

[0064] In summary, the angle-resolved XPS testing method provided by the present invention covers the surface of the sample to be tested with a conductive film having a hollow pattern, uses the hollow pattern on the conductive film as a mark, and directly aligns it with the central test position of the sample, thereby ensuring that the X-ray beam of the analyzer can accurately irradiate a specific area of ​​the sample; uses the hollow pattern of the conductive film as a mark to determine the test position, and when changing the angle of the sample relative to the analyzer, ensures the accuracy of the angle between the sample and the analyzer, thereby improving the accuracy of the angle-resolved XPS test.

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0066] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An angle-resolved XPS test method, characterized in that: include: Fix the sample to be tested on the sample holder; Covering the sample to be tested with a conductive film having a hollow pattern, and fixing the conductive film so that the hollow pattern of the conductive film is aligned with the central test position of the sample to be tested; The sample to be tested, which is covered with a conductive film, is placed in an XPS analyzer, and the center test position of the sample to be tested is located using an imaging device; At different test angles, the hollow pattern of the conductive film is used as a marker to determine the test position, and angle-resolved XPS tests are performed on the samples to be tested.

2. The angle-resolved XPS testing method according to claim 1, wherein: The sample to be tested is spherical.

3. The angle-resolved XPS testing method according to claim 2, wherein: The diameter of the sample to be tested is 100 to 5000 μm.

4. The angle-resolved XPS testing method according to claim 1, wherein: The sample to be tested is fixed on the sample holder by bonding with double-sided conductive copper glue.

5. The angle-resolved XPS testing method according to claim 1, wherein: The conductive film is a metal foil or a conductive polymer film.

6. The angle-resolved XPS testing method according to claim 1, wherein: The hollow pattern is a diamond shape.

7. The angle-resolved XPS testing method according to claim 6, wherein: The size of the short diagonal line of the hollow pattern is 1.5 to 2.5 times the size of the X-ray spot of the XPS analyzer.

8. The angle-resolved XPS testing method according to claim 1, wherein: The imaging device is an SXI imager.

9. The angle-resolved XPS testing method according to claim 1, wherein: The XPS analyzer is a PHI5000 Versaprobe III analyzer.

10. The angle-resolved XPS testing method according to claim 1, wherein: The test angle is between 10° and 90°.

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