Inspection methods for packaging substrates, electronic devices, and computer-readable storage media

Abstract

This application discloses a method for testing a packaged substrate, an electronic device, and a computer-readable storage medium. The method includes: obtaining a test sample with a blind via structure from the packaged substrate; the bottom of the blind via structure includes at least a first metal layer and a second metal layer; grinding the grain boundary between the first and second metal layers along a cross-section perpendicular to the test sample using an ion beam to form a groove on the cross-section of the test sample; performing backscatter diffraction diffraction on the groove using an electron beam to obtain a grain diffraction image corresponding to the bottom of the blind via, and obtaining a cross-sectional morphology image characterizing the grain boundary; combining the grain diffraction image and the cross-sectional morphology image for analysis to obtain microstructure information characterizing the bottom of the blind via. This method can effectively characterize the grain boundaries and microstructure of different copper layers at the bottom of the blind via of the packaged substrate, and is thus used for non-destructive structural characterization and performance analysis of the bottom of the blind via of the packaged substrate.

Description

Technical Field

[0001] This application relates to the field of packaging substrate technology, and in particular to a method for testing packaging substrates, electronic devices, and computer-readable storage media. Background Technology

[0002] The blind via stacked structure of a packaging substrate plays a crucial role in achieving electrical connections between surface and inner layer circuitry. The microstructure at the bottom of a blind via typically consists of three layers: an inner electroplated copper layer, a chemically deposited copper layer, and an outer via-filling electroplated copper layer. Due to the different deposition principles of electroplated and chemically deposited copper layers, there are differences in the crystallization state of the copper grains. These grain differences between layers create a complex microstructure. The microstructure at the bottom of the blind via has a significant impact on the reliability of the packaging substrate, especially under extreme environments such as thermal shock. Mismatches at grain boundaries can easily lead to microcracks, thereby causing interlayer interconnect failure.

[0003] Currently, on the one hand, it is difficult to obtain clear images of the bottom of blind holes using scanning electron microscopy (SEM), especially to clearly distinguish the grain boundaries and structures of different copper layers. On the other hand, characterizing the bottom of blind holes using transmission electron microscopy (TEM) is cumbersome to prepare and expensive.

[0004] Therefore, there is a lack of effective characterization and analysis methods for the microstructure at the grain boundaries of different processes at the bottom of blind vias, and the relationship between these microstructures and performance is not readily understood. This results in the failure modes of blind vias in packaging substrates not being fully understood and improved. Summary of the Invention

[0005] The main technical problem addressed by this application is to provide a method for testing a packaged substrate, an electronic device, and a computer-readable storage medium that can effectively characterize the grain boundaries and microstructure of different copper layers at the bottom of blind vias in a packaged substrate, thereby enabling non-destructive structural characterization and performance analysis of the bottom of blind vias in a packaged substrate.

[0006] To solve the above-mentioned technical problems, one technical solution adopted in this application is: the detection method includes:

[0007] A test sample with a blind via structure is obtained from a packaging substrate; the bottom of the blind via structure includes at least a first metal layer and a second metal layer;

[0008] Along the cross-section perpendicular to the sample under test, the grain boundary between the first metal layer and the second metal layer is ground using an ion beam to form a groove on the cross-section of the sample under test.

[0009] Backscatter diffraction of the groove with an electron beam is used to obtain a grain diffraction image corresponding to the bottom of the blind hole, and a cross-sectional morphology image characterizing the grain boundary is obtained.

[0010] By combining the grain diffraction image and the cross-sectional morphology image, microstructural information characterizing the bottom of the blind hole is obtained.

[0011] Optionally, the step of grinding the grain boundary between the first metal layer and the second metal layer along a cross-section perpendicular to the sample under test using an ion beam to form a groove on the cross-section of the sample under test includes:

[0012] Obtain a fixed angle between the irradiation direction of the electron beam and the inclination direction of the cross section of the sample under test;

[0013] Based on the fixed included angle, the relative angle between the two sides of the groove is determined, and the grain boundary is ground using the ion beam based on preset ion grinding parameters to form a groove on the cross-section of the sample to be tested.

[0014] Optionally, the step of determining the relative angle between the two sides of the groove based on the fixed included angle, and using the ion beam to grind the grain boundary based on preset ion grinding parameters to form a groove on the cross-section of the sample to be tested, includes:

[0015] By combining the preset vertical angle and the fixed included angle, the relative angle between the two sides of the groove is determined, such that 1 / 2 of the relative angle is equal to or greater than the incident angle of the electron beam relative to the groove.

[0016] Along the grain boundary, the cross-section of the sample under test is controlled to rotate horizontally, so as to use the ion beam to grind the grain boundary based on the ion grinding parameters to form a groove on the cross-section of the sample under test.

[0017] Optionally, the ion polishing parameters include at least one of the following: operating voltage of 3kV to 5kV, polishing temperature of less than or equal to 100℃, ion beam angle of 80° to 85°, and polishing time of 20 to 100 minutes.

[0018] Optionally, obtaining the test sample with a blind via structure from the packaging substrate includes:

[0019] An initial sample having the blind via structure was obtained from the packaging substrate;

[0020] The initial sample is ground and surface-treated according to the electron beam diffraction conditions to obtain the sample to be tested.

[0021] Optionally, the step of grinding and surface-treating the initial sample according to the electron beam diffraction conditions to obtain the sample to be tested includes:

[0022] The burr edges of the initial sample are polished to form a first sample, such that the cross-section of the first sample is parallel to the stage.

[0023] The cross-section of the first sample is placed horizontally inside the container, and organic material is filled into the container to obtain the cured second sample;

[0024] Based on the working distance between the stage and the electron beam, the second sample is ground to form a third sample;

[0025] Based on the back diffraction thickness of the electron beam, the surface scratches of the third sample are ground, and the ground third sample is polished to form the sample to be tested.

[0026] Optionally, the step of grinding the surface scratches of the third sample and polishing the ground third sample to form the test sample includes:

[0027] Using sandpaper of various grit sizes, the surface scratches of the third sample were ground in descending order of grit size;

[0028] The third sample after grinding is polished until the blind hole structure has no scratches under a preset microscope magnification, thus forming the sample to be tested.

[0029] Optionally, the analysis combining the grain diffraction image and the cross-sectional morphology image to obtain microstructural information characterizing the bottom of the blind hole includes:

[0030] Grain size and grain growth information are obtained from the grain diffraction image;

[0031] By combining the cross-sectional morphology image representing the grain boundary, the grain size, and the grain growth status information, the microstructure information representing the bottom of the blind hole is obtained.

[0032] To solve the above-mentioned technical problems, another technical solution adopted in this application is: an electronic device, the electronic device comprising:

[0033] Memory, used to store executable program code;

[0034] A processor is configured to call and run the executable program code from the memory, causing the electronic device to perform the detection method for the package substrate as described in any of the above-described embodiments.

[0035] To solve the above-mentioned technical problems, another technical solution adopted in this application is: a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the detection method for the packaging substrate as described in any of the above claims.

[0036] Unlike existing technologies, this application provides a method for testing a packaged substrate. The method includes: obtaining a test sample with a blind via structure from the packaged substrate; the bottom of the blind via structure includes at least a first metal layer and a second metal layer; grinding the grain boundary between the first and second metal layers along a cross-section perpendicular to the test sample using an ion beam to form a groove on the cross-section of the test sample; performing backscatter diffraction diffraction on the groove using an electron beam to obtain a grain diffraction image corresponding to the bottom of the blind via, and obtaining a cross-sectional morphology image characterizing the grain boundary; combining the grain diffraction image and the cross-sectional morphology image for analysis to obtain microstructure information characterizing the bottom of the blind via. This method can effectively characterize the grain boundaries and microstructure of different copper layers at the bottom of the blind via of the packaged substrate, and is thus used for non-destructive structural characterization and performance analysis of the bottom of the blind via of the packaged substrate. Attached Figure Description

[0037] Figure 1 This is an exemplary schematic diagram of the blind via stacked via structure in the detection method of the packaging substrate of this application;

[0038] Figure 2 This is a flowchart illustrating the first embodiment of the testing method for the packaging substrate of this application;

[0039] Figure 3 This is a flowchart illustrating the second embodiment of the testing method for the packaging substrate of this application;

[0040] Figure 4a This is an exemplary schematic diagram of the sample taking for the test of the packaging substrate testing method of this application;

[0041] Figure 4b This is an exemplary schematic diagram of the blind hole pre-grinding process in the inspection method of the packaging substrate of this application;

[0042] Figure 4c This is an exemplary schematic diagram of the preparation of a blind hole microstructure sample for the detection method of the packaging substrate of this application;

[0043] Figure 4d This is an exemplary schematic diagram of the sample size grinding process in the testing method for the packaging substrate of this application;

[0044] Figure 4e This is an exemplary schematic diagram of the fine grinding of a sample in the testing method for the packaging substrate of this application;

[0045] Figure 4f This is an exemplary schematic diagram of the sample surface reprocessing in the detection method of the packaging substrate of this application;

[0046] Figure 4g This is an exemplary schematic diagram of the EBSD characterization of the testing method for the packaging substrate of this application;

[0047] Figure 5a This is a first exemplary schematic diagram of the cross-sectional morphology image of the detection method for the packaging substrate of this application;

[0048] Figure 5b This is a second exemplary schematic diagram of the cross-sectional morphology image of the detection method for the packaging substrate of this application;

[0049] Figure 5c This is a third exemplary schematic diagram of the cross-sectional morphology image of the detection method for the packaging substrate of this application;

[0050] Figure 5d This is a fourth exemplary schematic diagram of the cross-sectional morphology image of the detection method for the packaging substrate of this application;

[0051] Figure 5e This is a fifth exemplary schematic diagram of the cross-sectional morphology image of the detection method for the packaging substrate of this application;

[0052] Figure 6a This is a first exemplary schematic diagram of the grain diffraction image of the detection method for the packaging substrate of this application;

[0053] Figure 6b This is a second exemplary schematic diagram of the grain diffraction image of the detection method for the packaging substrate of this application;

[0054] Figure 6c This is a third exemplary schematic diagram of the grain diffraction image of the detection method for the packaging substrate of this application;

[0055] Figure 6d This is a fourth exemplary schematic diagram of the grain diffraction image of the detection method for the packaging substrate of this application;

[0056] Figure 6e This is a fifth exemplary schematic diagram of the grain diffraction image of the detection method for the packaging substrate of this application;

[0057] Figure 7 This is a schematic diagram of the reverse polarity of the copper grains at the bottom of the blind hole in the detection method of the packaging substrate of this application;

[0058] Figure 8a This is a statistical diagram of the in-hole copper plating grain size in the testing method of the packaging substrate of this application;

[0059] Figure 8bThis is a statistical diagram of the copper grain size at the bottom of the hole in the testing method of the packaging substrate of this application;

[0060] Figure 9 This is an exemplary structural block diagram of an electronic device for the detection method of the packaged substrate of this application;

[0061] Figure 10 This is an exemplary structural block diagram of a computer-readable storage medium for the detection method of the packaging substrate of this application.

[0062] Reference numerals: 1. Outer layer of electroplated copper for filling holes; 2. Chemically deposited copper layer; 3. Inner layer of electroplated copper. Detailed Implementation

[0063] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0064] This embodiment takes into account that the function of the blind via stacked structure is to connect the surface layer circuitry and the inner layer circuitry, thereby achieving normal electrical conductivity of the circuit. The microstructure at the bottom of the blind via consists of three parts. A schematic diagram of the blind via stacked structure can be found in an exemplary embodiment. Figure 1 The bottom of the blind hole consists of an outer layer of electroplated copper 1, a chemically deposited copper layer 2, and an inner layer of electroplated copper 3.

[0065] Overall, the bottom of the blind via contains only one metallic element, copper. However, due to the different preparation principles of electroplated copper layers and chemically deposited copper layers, grain boundaries appear between the inner electroplated copper layer and the chemically deposited copper layer, or between the outer via-filling electroplated copper layer and the chemically deposited copper layer. These grain boundaries indicate differences in the crystallization state of the copper grains. Specifically, in electroplated copper layers, copper is deposited using electrodeposition. The copper grains in the inner electroplated copper layer tend to grow into columnar crystals along the filling direction, and the grain size is relatively large. The copper grains in the outer via-filling electroplated copper layer tend to grow randomly, without strong texture. In chemically deposited copper layers, a thin layer of copper is deposited through a redox reaction. The copper layer thickness is approximately several hundred nanometers, the grain size is small, and there are many grain boundaries.

[0066] Currently, scanning electron microscopy (SEM) imaging struggles to clearly characterize the microstructure at the bottom of blind vias. Furthermore, since only one metallic element exists at the bottom of a blind via, it's difficult to pinpoint the specific locations at grain boundaries after the copper-filling process. This makes it difficult to distinguish the microstructures of different electroplated copper layers, thus hindering the analysis of the microstructure at the bottom of the blind via and the relationship between structure and performance.

[0067] Therefore, this embodiment proposes an electron backscatter diffraction (EBSD) sample and its preparation method for characterizing the microstructure at blind hole grain boundaries.

[0068] Please see Figure 2 , Figure 2 This is a schematic flowchart of the first embodiment of the testing method for the packaged substrate of this application. It should be noted that if substantially the same result is obtained, the method of this application is not necessarily identical. Figure 2 The illustrated process sequence is limited. For example... Figure 2 As shown, the detection method includes:

[0069] Step S210: Obtain the test sample with a blind via structure from the packaging substrate; the bottom of the blind via structure includes at least a first metal layer and a second metal layer;

[0070] The packaging substrate can be the core structure in electronic devices used to carry and interconnect electronic components, supporting the chip and providing conductivity. The packaging substrate mainly consists of an insulating substrate, a copper layer, an organic build-up film, and solder resist ink. The function of the blind via stacked structure on the packaging substrate is to connect the various circuit layers, achieving normal electrical conductivity. The blind via structure can also be a blind via stacked structure. The sample to be tested can be a sample that meets the conditions for electron backscatter diffraction and ion beam polishing.

[0071] In one exemplary embodiment, the first metal layer and the second metal layer may be an inner electroplated copper layer and a chemically deposited copper layer. In another exemplary embodiment, the first metal layer and the second metal layer may be an outer electroplated copper layer and a chemically deposited copper layer.

[0072] Step S220: Along the cross-section perpendicular to the sample to be tested, the grain boundary between the first metal layer and the second metal layer is ground using an ion beam to form a groove on the cross-section of the sample to be tested.

[0073] The cross-section can be the internal structural surface exposed after the sample is cut. Ion beam cross-section polishing (CP) utilizes ion beam polishing technology to extract a cross-section of the sample perpendicular to its cross-section. This avoids the stress effects generated during the polishing process, creating grooves on the cross-section at the bottom of blind holes. These grooves expose the internal structure at the bottom of the blind hole, facilitating subsequent analysis of grain boundaries and grain orientations of different metal layers.

[0074] Specifically, to allow the electron beam to penetrate the microstructure at the bottom of the blind hole at a suitable angle, an ion beam can be used to grind and groove the bottom of the blind hole, exposing its internal structure and making it easier to analyze. Simultaneously, the groove angle can also take into account the electron beam irradiation conditions to ensure that the electron beam can irradiate the grain boundaries at a suitable angle during electron backscattering diffraction analysis.

[0075] Step S230: Backscatter diffraction is performed on the groove using an electron beam to obtain a grain diffraction image corresponding to the bottom of the blind hole, and a cross-sectional morphology image characterizing the grain boundary is obtained.

[0076] Specifically, the electron beam can be a high-energy electron beam. When the electron beam irradiates the grooves of the sample under test, it can generate backscattered electrons or other signals, thereby obtaining a grain diffraction image. The grain diffraction image can characterize the growth status and size of the grains and can be used to analyze stress concentration points and possible microcracks at grain boundaries. The cross-sectional morphology image can be an image obtained by tools such as an electron microscope, used to show the specific location of the grain boundaries.

[0077] Step S240: Analyze the grain diffraction image and the cross-sectional morphology image to obtain microstructure information characterizing the bottom of the blind hole.

[0078] Specifically, microstructure information refers to the microstructure of different metal layers at the grain scale, including grain size, orientation, grain boundary distribution, and the presence of microcracks and defects. By obtaining microstructure information, we can gain a deeper understanding of the plating quality at the bottom of blind vias and the bonding at grain boundaries, analyze potential failure areas of blind vias, and thus improve the design and manufacturing process of packaging substrates.

[0079] In one exemplary embodiment, firstly, a sample to be tested with a blind hole bottom structure is prepared, and this sample is designed to clearly show the blind hole structure under a metallographic microscope. The region containing the blind hole structure is then treated with an argon ion beam to create a groove with a large angle at the bottom of the blind hole. The angle of this groove satisfies the condition for an electron beam to acquire information at grain boundaries. For example, if the angle between the EBSD electron gun and the sample is θ, and the angle of the groove at the bottom of the blind hole is α, then the condition for the electron beam to acquire information at grain boundaries is θ ≥ 90° - 1 / 2α. Simultaneously, the ion polishing parameters of the ion beam are controlled to ensure that the metallographic microscope can clearly characterize the microstructure at the bottom of the blind hole at 50× magnification, so that the groove on the sample surface does not affect the EBSD image quality. Then, carbon is sprayed onto the sample surface to increase conductivity, and EBSD imaging is performed to characterize the microstructure at the bottom of the blind hole. This allows for the effective preparation of samples characterizing blind hole structures and the analysis of the specific microstructure at the bottom of the blind hole, and can be extended to the preparation of samples for characterizing the microstructure at grain boundaries of various materials using different processes. Not only can it meet the requirements of EBSD preprocessing conditions, but it can also clearly identify the specific sites at the grain boundaries at the bottom of blind holes through the SEM images displayed by EBSD. The obtained EBSD images are of high quality and can be used to study the structure and properties of blind holes as well as the microstructure at the grain boundaries of different materials.

[0080] This embodiment utilizes an ion beam to create grooves at the bottom of blind vias along a cross-section perpendicular to the sample under test. Then, an electron beam is used to perform backscatter diffraction on the grooves to obtain grain diffraction images and cross-sectional morphology images. Combined analysis can effectively characterize the grain boundaries and microstructure of different copper layers at the bottom of blind vias on the packaging substrate. This can then be used for non-destructive structural characterization and performance analysis of the bottom of blind vias on the packaging substrate.

[0081] This embodiment considers that the blind via copper filling process for interlayer interconnects is a key technology for achieving high-density interconnect manufacturing, and the structure and properties of electroplated copper are key factors affecting the high reliability of interlayer interconnects. There are significant differences in the microstructure of copper grains between the chemically deposited copper layer and the electroplated copper layer, resulting in a high degree of lattice mismatch at the grain boundaries. From the perspective of phase boundary energy, the energy at the total grain boundaries is higher. In the analysis of the results of thermal shock reliability testing of the packaged substrate, if the local thermal stress exceeds the threshold during thermal shock, microcracks are easily generated between the chemically deposited copper layer and the inner electroplated copper layer, and / or between the chemically deposited copper layer and the outer via-filling electroplated copper layer, leading to failure.

[0082] However, on the one hand, scanning electron microscopy imaging cannot yet clearly characterize the microstructure of the bottom of blind vias. Furthermore, since only one metallic element exists at the bottom of a blind via, it is difficult to clearly identify the specific sites at the grain boundaries after the copper filling process is completed. It is difficult to distinguish the microstructure of different electroplated copper layers, thus making it impossible to analyze the microstructure of the bottom of the blind via and establish the relationship between structure and performance. On the other hand, characterizing the bottom of blind vias using transmission electron microscopy is cumbersome to prepare and expensive to perform.

[0083] Therefore, this embodiment proposes a failure mechanism for microcracks and a method for detecting the microstructure and performance of blind via bottoms, effectively enabling detailed analysis of the microstructure of blind via bottoms and blind via failure, thereby allowing for the regulation of the copper grain microstructure of the packaging substrate and the reliability of its blind vias. Please refer to the following for details. Figure 3 , Figure 3 This is a flowchart illustrating a second embodiment of the testing method for the packaging substrate of this application. In this embodiment, the method includes the following steps:

[0084] Step S310: Obtain an initial sample having the blind via structure from the packaging substrate;

[0085] Specifically, samples can be taken from areas where blind via structures are concentrated on a packaging substrate that has already been processed through normal procedures. In an exemplary embodiment, please refer to... Figure 4a It can control the size of the sample to be tested to not exceed 30mm×30mm×30mm.

[0086] Step S320: According to the electron beam diffraction conditions, the initial sample is ground and surface-treated to obtain the sample to be tested.

[0087] Specifically, to obtain clear grain diffraction patterns, the sample under test can be controlled to meet preset electron beam diffraction conditions. If the surface of the sample under test is too rough or there are other interfering factors, it can easily affect the accuracy of diffraction. Therefore, when grinding and surface treating the initial sample, it is essential to ensure that the final sample under test achieves a surface quality and state suitable for diffraction.

[0088] In one exemplary embodiment, electron beam diffraction conditions may include the accelerating voltage, beam current intensity, and incident angle of the electron beam.

[0089] Further, step S320 includes:

[0090] The burr edges of the initial sample are polished to form a first sample, such that the cross-section of the first sample is parallel to the stage.

[0091] Specifically, to ensure that the cross-section containing the blind hole structure is parallel to the sample stage during sample preparation, signal loss can be avoided during EBSD diffraction pattern acquisition. In an exemplary embodiment, please refer to... Figure 4b The edges of the initial sample can be polished so that the surface of the first sample after polishing is free of obvious burrs, thereby making the cross-section (observation surface) of the sample parallel to the sample stage.

[0092] The cross-section of the first sample is placed horizontally inside the container, and organic material is filled into the container to obtain the cured second sample;

[0093] Specifically, organic materials are used to ensure that there are no obvious air bubbles after the second sample is prepared, so as not to affect EBSD characterization observation. These organic materials can be organic materials with good flowability, including but not limited to epoxy resins, silicones, and polyurethane potting compounds.

[0094] In one exemplary implementation, please refer to Figure 4c For the first sample after pre-grinding, the cross-section of the first sample containing the blind hole microstructure is placed horizontally upward in the container, and the container is filled with organic material with good flowability to be cured. It is left to stand for at least 5 minutes to ensure that the organic material is completely cured to form the cured second sample. It is ensured that no obvious bubbles are generated after the sample preparation is completed so as not to affect the subsequent characterization and observation.

[0095] Based on the working distance between the stage and the electron beam, the second sample is ground to form a third sample;

[0096] Specifically, since the distance between the stage and the electron gun probe is limited during EBSD imaging, larger samples may touch the probe and cause damage to the instrument. Therefore, the size of the second sample can be ground to form a third sample.

[0097] In one exemplary implementation, please refer to Figure 4d The second sample is ground by a grinder to form the third sample, and the size of the third sample is controlled within 10mm×10mm×10mm.

[0098] Based on the back diffraction thickness of the electron beam, the surface scratches of the third sample are ground, and the ground third sample is polished to form the sample to be tested.

[0099] Specifically, sandpaper of various grit sizes can be used to grind the surface scratches of the third sample in descending order of grit size; the ground third sample is then polished until the blind hole structure is free of scratches under a preset microscope magnification, thus forming the sample to be tested.

[0100] In one exemplary embodiment, considering that EBSD data originates from a region less than 100 nm thick on the sample surface, and that obvious scratches cannot be removed in subsequent steps, ion beam polishing is only performed on nanoscale surfaces. Therefore, please refer to... Figure 4e The third sample was ground using sandpaper of different grit sizes: sandpaper with a grit size of 10 μm or larger, sandpaper ranging from 3 μm to 10 μm, and sandpaper with a grit size of less than 3 μm. After grinding, the sample was polished using a polishing machine, and the process was observed using a metallographic microscope until a clear blind hole structure appeared at 50× magnification, with no obvious scratches visible in the field of view, and the blind hole structure was clearly visible with a hole diameter within the processing specification range.

[0101] Step S330: Obtain the fixed angle between the irradiation direction of the electron beam and the tilt direction of the cross section of the sample to be tested;

[0102] Specifically, a fixed angle refers to the angle between the direction of electron beam irradiation and the cross-section of the sample under test. In microscopic analysis, this angle is usually fixed to ensure that the electron beam is incident on the sample surface in a specific manner.

[0103] Step S340: Based on the fixed included angle, determine the relative angle between the two sides of the groove, and use the ion beam to grind the grain boundary based on the preset ion grinding parameters to form a groove on the cross-section of the sample to be tested.

[0104] Specifically, the shape of the groove and the relative angle of the two side edges need to be precisely controlled to ensure that key areas such as grain boundaries are exposed to the maximum extent, so that the microstructure at the bottom of the blind hole or at the grain boundary can be observed more clearly in electron beam analysis.

[0105] Furthermore, the region containing the blind hole microstructure observed under a metallographic microscope is subjected to argon ion beam polishing. The polishing mode of the ion beam is controlled to be suitable for bombarding copper metal grains. The argon ion beam polishing parameters include at least one of the following: operating voltage 3kV to 5kV, polishing temperature less than or equal to 100℃, ion beam angle 80° to 85°, and polishing time 20 to 100 minutes. More preferably, the polishing time is 50 to 100 minutes, as the grooves at this polishing time result in higher imaging quality of the grain diffraction image.

[0106] During the grinding process at the grain boundaries at the bottom of the blind hole by ion beam, the sample under test can be kept rotating horizontally to complete the uniform etching of the groove.

[0107] Further, step S340 includes:

[0108] By combining the preset vertical angle and the fixed included angle, the relative angle between the two sides of the groove is determined, such that 1 / 2 of the relative angle is equal to or greater than the incident angle of the electron beam relative to the groove; along the grain boundary, the cross section of the sample to be tested is controlled to rotate horizontally, so that the ion beam can be used to grind the grain boundary based on the ion grinding parameters to form a groove on the cross section of the sample to be tested.

[0109] Specifically, half the relative angle between the two sides of the groove should be equal to or greater than the electron beam incident angle. This ensures that the electron beam can effectively irradiate the interior of the groove, especially key areas such as grain boundaries. This ensures that the electron beam can fully penetrate the sample, thereby obtaining accurate diffraction data or morphological information. Horizontal rotation refers to the rotation of the sample under test on a horizontal plane, allowing the ion beam to uniformly grind along the grain boundaries, resulting in a clearly visible groove line in the cross-section.

[0110] In one exemplary implementation, please refer to Figure 4f and Figure 4g Assuming the electron beam emitted by the electron gun in the EBSD device is at a fixed angle of 20° to the sample, the angle at which the groove appears at the bottom of the blind hole must be greater than or equal to 140°. Otherwise, it will severely affect the signal in the subsequent EBSD characterization, leading to signal loss. A clearly visible groove line is required on the sample surface. After ion beam polishing, the polished area should be sealed and marked immediately.

[0111] Step S350: Backscatter diffraction is performed on the groove using an electron beam to obtain a grain diffraction image corresponding to the bottom of the blind hole, and a cross-sectional morphology image characterizing the grain boundary is obtained.

[0112] In one exemplary embodiment, after argon ion beam polishing, signal enhancement processing is performed on the test sample whose polishing effect has been confirmed. By sputtering a conductive coating onto the surface of the test sample, a good conductive coating can be provided for EBSD characterization, thereby obtaining a good diffraction pattern. The conductive coating includes, but is not limited to, carbon layers, gold layers, etc.

[0113] Step S360: Obtain information on grain size and grain growth status from the grain diffraction image;

[0114] In one exemplary implementation, reference may be made to Figure 4g The microstructure of the sample surface is detected using a super depth-of-field 3D microscope or a scanning electron microscope. Specifically, the sample is fixed on an inclined stage, and the microstructure of the bottom of the blind hole is characterized by EBSD to obtain a grain diffraction image (EBSD image). At the same time, the information of the grain boundary at the bottom of the blind hole can be confirmed by cross-sectional morphology image (SEM image) using a scanning electron microscope. Confirming the specific location of the grain boundary helps to analyze the microscopic information such as the size and orientation of copper grains at the grain boundary.

[0115] Step S370: By combining the cross-sectional morphology image characterizing the grain boundary, the grain size, and the grain growth status information, microstructure information characterizing the bottom of the blind hole is obtained.

[0116] In one exemplary embodiment, ion polishing can be a method of sputtering a material surface using an argon ion beam. This method does not cause mechanical damage to the sample and can obtain a high-quality sample with a smooth surface. In this embodiment, ion polishing is used to prepare an EBSD sample, resulting in a smooth surface. The following content compares different ion polishing conditions to determine the optimal conditions for obtaining high-quality EBSD images.

[0117] When the ion beam incident angle is ≥80°, the ion beam irradiation angle is almost parallel to the sample processing surface, which can reduce unevenness caused by differences in crystal orientation and compositional etching rates, resulting in a smooth processing surface. To compare the effect of grinding time on sample flatness, two stacked holes in the same region were selected as the grinding targets of the ion beam, and experimental groups with different grinding times were set up. Please refer to [link to relevant documentation]. Figures 5a-5e , Figures 5a-5e The images show the SEM images of the grooves on the bottom surface of the blind holes in each experimental group, representing the grooves after grinding times of 20 minutes, 35 minutes, 50 minutes, 65 minutes, and 80 minutes. Figure 5a Angle α groove under a grinding time of 20 minutes; Figure 5b The b-angle groove is formed after a grinding time of 35 minutes. Figure 5c The c-angle groove is formed after a grinding time of 50 minutes. Figure 5d The d-angle groove is formed under a grinding time of 65 minutes; Figure 5e The image shows the groove at angle e after 80 minutes of grinding. It can be seen that angles a, b, c, d, and e gradually increase, with angles d and e exceeding 140°.

[0118] in, Figure 5a The results show that at a grinding time of 20 minutes, only the central region of the bottom of the blind via exhibits a groove, the grain boundaries are not clearly defined, and there are many uneven areas on the surface. The groove angle 'a' at the bottom of the blind via indicates a significant amount of unresolved areas. As the grinding time increases, the etching degree of the grooves at the grain boundaries at the bottom of the blind via gradually increases. Figure 5b The results show that even after 35 minutes of grinding, the sample surface still has bumps, resulting in localized roughness. The angle of the groove at the bottom of the blind hole is b. Figure 5c The results show that when the grinding time is 50 minutes, the quality of the EBSD image is improved, but unresolved areas still appear at the grain boundaries in the EBSD image. Figure 5d The image shows that when the grinding time is 65 minutes, the angle of the groove area at the bottom of the blind hole is d (d≥140°), the grain boundary is relatively clear, and the EBSD image only shows dot-like unresolved areas. Figure 5e The image shows that when the grinding time is 80 minutes, the bottom groove angle of the blind hole is 'e'. Microscopically, the surface is relatively smooth, the grain boundaries are clear, and the EBSD image quality is high. This indicates that... Figures 5a-5e The formation of grooves is mainly due to the difference in etching rates, which allows the grooves to be positioned at the grain boundaries at the bottom of blind vias. The microstructure of copper grains deposited in chemically deposited copper layers and inner electroplated copper layers differs. Chemically deposited copper layers produce smaller copper grains with more grain boundaries and higher energy, making them more easily etched during ion beam bombardment, thus creating grooves.

[0119] After processing the experimental groups at each of the above grinding times using EBSD post-processing software, EBSD images of the microstructure of copper grains at the bottom of blind holes at different grinding times were obtained, as shown below. Figures 6a-6e As shown. Figure 6a The image shows a large area of ​​white nodes in the upper left corner. These white nodes represent unresolved regions with low resolution. Figure 6a Corresponding to Figure 5a The SEM image shows that the unevenness of the unresolved region affects the scattering ability of the incident electrons. Figure 6eThe absence of numerous, unresolved white dots indicates a high quality EBSD image. Therefore, an ion beam polishing time of 50–100 minutes produces a high-quality EBSD image.

[0120] Furthermore, the microstructure of the copper grains at the bottom of the blind via was characterized, mainly focusing on the analysis of grain size and grain growth, such as... Figure 7 As shown. Analysis of grain morphology reveals that the electroplated copper grains within the holes grow randomly without strong texture. The copper grains at the bottom of the holes, which serve as the base copper, mainly grow vertically, with their crystal orientation biased towards the 001 crystal plane. Analysis of grain size... Figure 8a The average grain size of the electroplated copper within the holes shown is approximately 0.69 μm. Figure 8b The copper grain size at the bottom of the hole shown is small.

[0121] In this embodiment, a sample with a blind via bottom structure is initially ground to obtain a clearly visible blind via structure under a microscope, and the specific location for observation is determined. Argon ion beam polishing technology is then used to process the blind via structure to be observed, carefully controlling the angle of the groove at the bottom of the blind via. Finally, the microstructure of the blind via bottom is characterized using EBSD equipment. Therefore, this method of slicing the blind via bottom not only eliminates the tedious step of confirming the grain boundary information at the bottom of the blind via, but also allows for simultaneous confirmation of grain boundary information within the preprocessing conditions required by EBSD. Furthermore, it can be used to study the microstructure of copper grains at the bottom of the blind via, including grain size and grain orientation. This method is fully applicable to the study of blind via structures in packaging substrates, and is convenient, quick, and simple to operate.

[0122] Please see Figure 9 , Figure 9 This is an exemplary structural block diagram of an electronic device using the detection method for the packaged substrate of this application. For example... Figure 9 As shown, the electronic device 900 of this application may include a processor 901 and a memory 902, wherein the processor 901 and the memory 902 communicate via a bus. The memory 902 stores program instructions for detecting a packaged substrate, which, when executed by the processor 901, cause the processor to implement a method for detecting a packaged substrate as described in the above embodiments.

[0123] Please see Figure 10 , Figure 10 This is an exemplary structural block diagram of a computer-readable storage medium for the detection method of the packaging substrate of this application. Figure 10 As shown, the computer-readable storage medium 1000 stores a computer program 1001. When the computer program 1001 is run by a processor on a computer, it causes the computer to execute the aforementioned related method steps to implement a method for detecting a packaged substrate in the above embodiments.

[0124] The above method involves obtaining a test sample with a blind via structure from a packaging substrate. The bottom of the blind via structure includes at least a first metal layer and a second metal layer. Along a cross-section perpendicular to the test sample, an ion beam is used to grind the grain boundary between the first and second metal layers, forming a groove on the cross-section of the test sample. Backscatter diffraction is performed on the groove using an electron beam to obtain a grain diffraction image corresponding to the bottom of the blind via, as well as a cross-sectional morphology image characterizing the grain boundary. By combining the grain diffraction image and the cross-sectional morphology image for analysis, microstructural information characterizing the bottom of the blind via is obtained. This method can effectively characterize the grain boundaries and microstructure of different copper layers at the bottom of the blind via on the packaging substrate, and is thus used for non-destructive structural characterization and performance analysis of the bottom of the blind via on the packaging substrate.

[0125] In the several embodiments provided in this application, it should be understood that the disclosed methods, electronic devices, and storage media can be implemented in other ways. For example, the device embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0126] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0127] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0128] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute all or part of the steps of the detection method described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0129] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for detecting a packaging substrate, characterized in that, The detection method includes: A test sample with a blind via structure is obtained from a packaging substrate; the bottom of the blind via structure includes at least a first metal layer and a second metal layer; Along the cross-section perpendicular to the sample under test, the grain boundary between the first metal layer and the second metal layer is ground using an ion beam to form a groove on the cross-section of the sample under test. Backscatter diffraction of the groove with an electron beam is used to obtain a grain diffraction image corresponding to the bottom of the blind hole, and a cross-sectional morphology image characterizing the grain boundary is obtained. By combining the grain diffraction image and the cross-sectional morphology image for analysis, microstructural information characterizing the bottom of the blind hole is obtained; The step of grinding the grain boundary between the first metal layer and the second metal layer along a cross-section perpendicular to the sample under test using an ion beam to form a groove on the cross-section of the sample under test includes: Obtain a fixed angle between the irradiation direction of the electron beam and the inclination direction of the cross section of the sample under test; By combining the preset vertical angle and the fixed included angle, the relative angle between the two sides of the groove is determined, such that 1 / 2 of the relative angle is equal to or greater than the incident angle of the electron beam relative to the groove. Along the grain boundary, the cross-section of the sample to be tested is controlled to rotate horizontally, so that the grain boundary is ground by the ion beam based on preset ion grinding parameters to form a groove on the cross-section of the sample to be tested.

2. The detection method according to claim 1, characterized in that, The ion polishing parameters include at least one of the following: working voltage 3kV to 5kV, polishing temperature less than or equal to 100℃, ion beam angle 80° to 85°, and polishing time 20 to 100 minutes.

3. The detection method according to claim 1, characterized in that, The process of obtaining the test sample with a blind via structure from the packaging substrate includes: An initial sample having the blind via structure was obtained from the packaging substrate; The initial sample is ground and surface-treated according to the electron beam diffraction conditions to obtain the sample to be tested.

4. The detection method according to claim 3, characterized in that, The process of grinding and surface treating the initial sample according to the electron beam diffraction conditions to obtain the sample to be tested includes: The burr edges of the initial sample are polished to form a first sample, such that the cross-section of the first sample is parallel to the stage. The cross-section of the first sample is placed horizontally inside the container, and organic material is filled into the container to obtain the cured second sample; Based on the working distance between the stage and the electron beam, the second sample is ground to form a third sample; Based on the back diffraction thickness of the electron beam, the surface scratches of the third sample are ground, and the ground third sample is polished to form the sample to be tested.

5. The detection method according to claim 4, characterized in that, The process of grinding the surface scratches of the third sample and polishing the ground third sample to form the test sample includes: Using sandpaper of various grit sizes, the surface scratches of the third sample were ground in descending order of grit size; The third sample after grinding is polished until the blind hole structure has no scratches under a preset microscope magnification, thus forming the sample to be tested.

6. The detection method according to claim 1, characterized in that, The analysis combining the grain diffraction image and the cross-sectional morphology image yields microstructural information characterizing the bottom of the blind hole, including: Grain size and grain growth information are obtained from the grain diffraction image; By combining the cross-sectional morphology image representing the grain boundary, the grain size, and the grain growth status information, the microstructure information representing the bottom of the blind hole is obtained.

7. An electronic device, characterized in that, The electronic device includes: Memory, used to store executable program code; A processor is configured to call and run the executable program code from the memory, causing the electronic device to perform the detection method for the package substrate as described in any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the method for detecting a packaged substrate as described in any one of claims 1 to 6.

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