Method for measuring the metal thermal expansion coefficient in hybrid bonded samples using an atomic force microscope heating module

Abstract

The present application relates to a kind of methods for measuring the thermal expansion coefficient of metal in mixed bonding sample using atomic force microscope heating module, comprising the following steps: building heating mechanics platform on atomic force microscope;Scan metal-dielectric sample at room temperature to obtain initial topography data;Gradient heating is carried out to metal-dielectric sample and surface topography characterization is carried out;Atomic force microscope scanning data is handled;Based on the initial topography data obtained and the relative topography change information extracted, and the thermal expansion coefficient Δ of metal relative to dielectric is calculated by thermal expansion model.Compared with prior art, the thermal expansion coefficient of metal relative to dielectric can be accurately calculated, to meet the needs of accurate control of thermal expansion behavior of metal and dielectric in mixed bonding technology, and then control the height of metal relative to dielectric in CMP process in mixed bonding, the reliability of bonding interface and the performance of semiconductor device can be improved.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional packaging technology for integrated circuits, and in particular to a method for measuring the coefficient of thermal expansion of metals in mixed-bonded samples using an atomic force microscope heating module. Background Technology

[0002] In hybrid bonding technology for 3D packaging of integrated circuits, metals, as critical interconnect materials, have a significant impact on the reliability of the bonding interface due to their thermal expansion behavior. Hybrid bonding technology requires a tight bond between the metal and the dielectric to achieve electrical connection and mechanical support between chips. However, because the coefficient of thermal expansion (CTE) of metals differs significantly from that of dielectrics, the expansion of the metal during high-temperature bonding may lead to stress concentration at the bonding interface, and even cause failures such as delamination or cracking. These problems severely affect the performance and lifespan of semiconductor devices; therefore, accurately measuring and understanding the thermal expansion behavior of metals during hybrid bonding is crucial.

[0003] Currently, researchers are attempting to measure the coefficient of thermal expansion (CTE) of thin films or solid materials using various techniques. For example, document CN112986320A proposes a method for determining the CTE of thin films. This method involves fabricating a stepped structure on the surface of the film under test and then using atomic force microscopy or nanoindentation to detect changes in film thickness at different temperatures. This method is suitable for thin film materials that are difficult to peel off from the substrate, such as Low-k films on silicon substrates. However, this method primarily focuses on determining the CTE of thin film materials, without considering the relative thermal expansion behavior between metals and dielectrics, and does not provide a solution for measurement in an oxygen-free environment.

[0004] Document CN118130532A discloses a method for testing the thermal expansion response of solid materials based on atomic force microscopy. This method involves contacting the thermal probe of an atomic force microscope with the solid material and applying AC excitation to induce thermal expansion. While this method can determine the thermal expansion response of solid materials, it primarily targets inorganic solid electrolyte materials and does not specifically address the determination of the relative thermal expansion coefficient between metals and dielectrics. Furthermore, the method does not explicitly mention how to conduct measurements in an oxygen-free environment to prevent the influence of metal oxidation on the measurement results.

[0005] In summary, the existing technology has the following main problems:

[0006] There is a lack of effective methods for measuring the relative thermal expansion behavior between metals and dielectrics in hybrid bonding technologies. Existing techniques mostly focus on determining the coefficient of thermal expansion of a single material (such as thin films or inorganic solid electrolytes), without fully considering the interaction between the metal and the dielectric and the accurate measurement of the relative coefficient of thermal expansion.

[0007] During the measurement process, the influence of metal oxidation on the measurement results is difficult to avoid. Especially in high-temperature environments, metal oxidation can lead to distorted measurement data, failing to accurately reflect the actual thermal expansion behavior of the metal. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art by providing a method for measuring the thermal expansion coefficient of a metal in a hybrid bonded sample using an atomic force microscope heating module. This method can accurately calculate the thermal expansion coefficient of the metal relative to the dielectric, thereby meeting the requirement for precise control of the thermal expansion behavior of the metal and dielectric in hybrid bonding technology. This allows for control of the height of the metal relative to the dielectric in the CMP process during hybrid bonding, which can improve the reliability of the bonding interface and the performance of semiconductor devices.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] This invention provides a method for measuring the coefficient of thermal expansion of a metal in a mixed-bonded sample using an atomic force microscope heating module, characterized by comprising the following steps:

[0011] S1. Construct a heating mechanics platform on an atomic force microscope;

[0012] S2. Based on the heating mechanics platform built in S1, scan the metal-dielectric sample at room temperature to obtain initial morphology data;

[0013] S3. Using the heating mechanics platform built in S1, the metal-dielectric sample was subjected to gradient heating in an oxygen-free environment, and the surface morphology was characterized in real time during the heating process.

[0014] S4. The data obtained from gradient heating and morphology characterization in S3 are processed to extract the relative morphological change information of the metal and dielectric.

[0015] S5. Based on the initial morphology data obtained in S2 and the relative morphology change information extracted in S4, the thermal expansion coefficient Δα of the metal relative to the dielectric is calculated using the thermal expansion model.

[0016] Furthermore, S1 specifically includes the following steps:

[0017] After loading the probe onto the ceramic heating probe holder, the ceramic heating probe holder is installed on the atomic force microscope scanner, and the laser is adjusted onto the probe using the shading method.

[0018] Activate the heated sample stage, close the atomic force microscope scanning control software and disconnect the power, install the pressure thermocouple, and then reopen the atomic force microscope scanning control software.

[0019] Install the annular gas channel on the heated sample stage;

[0020] Use thermally conductive adhesive to fix the sample in the sample tray and place it on the magnetic suction surface of the pressure thermocouple;

[0021] Assemble and turn on the fluid cooling system and thermal application controller.

[0022] Furthermore, in S1, the probe is a probe without a metal coating.

[0023] Furthermore, in S1, the specific steps also include:

[0024] An annular gas channel is installed on the heating sample stage to introduce inert or reducing gas during heating, creating an oxygen-free environment to prevent metal oxidation.

[0025] Furthermore, S2 specifically includes the following steps:

[0026] Under normal temperature conditions, set the scanning parameters of the atomic force microscope, including scanning range, resolution and scanning rate;

[0027] Bring the probe close to the surface of the metal-dielectric sample and begin scanning;

[0028] Record and save the initial topographic data obtained from the scan, including the height information of the metallic and dielectric regions.

[0029] Furthermore, S3 specifically includes the following steps:

[0030] Set a temperature gradient and gradually heat the sample from room temperature to multiple target temperature points in an oxygen-free environment.

[0031] Maintain a constant temperature at each target temperature for a preset time to ensure uniform sample temperature;

[0032] Under constant temperature conditions, the surface morphology of the sample was scanned using an atomic force microscope, and morphology data at different temperatures were recorded.

[0033] After heating and scanning at all temperature points are completed, turn off the heating module and allow the sample to cool naturally to room temperature.

[0034] Furthermore, S4 specifically includes the following steps:

[0035] The scan data acquired in S3 is preprocessed, including noise removal and data drift correction;

[0036] Plane fitting is performed on the preprocessed data to eliminate the influence of probe tilt on the measurement results;

[0037] The height difference data between the metal region and the surrounding dielectric region was extracted using cross-sectional analysis tools.

[0038] The extracted height difference data is compared and analyzed with the initial morphology data obtained in step S2 to calculate the relative morphological changes of the metal and dielectric at different temperatures.

[0039] Furthermore, S5 specifically includes the following steps:

[0040] Substitute the relative morphological changes of the metal and dielectric extracted in step S4 into the calculation formula of the thermal expansion model:

[0041] Δl=(l+2dν)ΔαΔT;

[0042] Where Δl is the total deformation of the metal during thermal expansion, ν is the Poisson's ratio of the metal, l is the initial height of the metal through hole, d is the diameter of the metal through hole, Δα is the thermal expansion coefficient of the metal and the dielectric, and ΔT is the temperature change.

[0043] Solve the calculation formula of the thermal expansion model to obtain the thermal expansion coefficient Δα of the metal relative to the dielectric.

[0044] Furthermore, in S5, the process of obtaining the various parameters in the thermal expansion model specifically includes:

[0045] The initial height l and diameter d of the metal through hole are measured from the initial morphology data obtained from S2.

[0046] The Poisson's ratio ν of a metal can be obtained from its known properties or by querying a materials database.

[0047] The temperature change ΔT is determined from the temperature data recorded during the gradient heating process of S3;

[0048] Δl was obtained by comparing the relative morphological changes of the metal and dielectric at different temperatures in S4.

[0049] Furthermore, the specific process of measuring the initial height l and diameter d of the metal through-hole from the initial morphology data obtained from S2 includes:

[0050] Open the initial morphology data in the atomic force microscopy analysis software;

[0051] Geometric features of the metal through-hole region are extracted using topographic data analysis tools.

[0052] The height analysis function is used to measure the height difference between the top of the metal via and the substrate dielectric to determine the initial height l of the metal via;

[0053] Use a diameter measuring tool to measure the diameter d at the opening of the metal through hole.

[0054] Furthermore, the specific process of obtaining Δl by comparing the relative morphological changes of the metal and dielectric at different temperatures in S4 includes:

[0055] The topographic data obtained by scanning at different temperatures are aligned with the topographic data at the initial temperature in the same spatial coordinate system;

[0056] Multiple measurement points were marked at the center of the metal via and in the surrounding dielectric area.

[0057] Using the cross-sectional analysis function of atomic force microscopy software, the height difference between the metal surface and the dielectric surface at the same location point was measured and recorded along the vertical direction.

[0058] The metal-dielectric height difference at the initial temperature is used as a reference;

[0059] Subtracting the baseline value from the height difference at each target temperature yields multiple Δl values.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] 1) This invention addresses the critical issue of bonding interface failure caused by the difference in thermal expansion coefficients between metals and dielectrics in hybrid bonding technology. Existing technologies, such as the method for determining the thermal expansion coefficient of thin films (CN112986320A) and the method for testing the thermal expansion response of solid materials (CN118130532A), have limitations such as not considering the relative thermal expansion behavior of metals and dielectrics and not providing a measurement scheme in an oxygen-free environment. This invention, through the heating module of an atomic force microscope, can perform gradient heating and real-time characterization of metal-dielectric samples in an oxygen-free environment, effectively avoiding interference from metal oxidation. Combined with a thermal expansion model, it accurately calculates the relative thermal expansion coefficient, providing crucial data support for the high degree of control between metals and dielectrics in hybrid bonding.

[0062] 2) This invention also possesses high-precision in-situ characterization and real-time data analysis capabilities. From the detection process perspective, leveraging the high-resolution scanning function of an atomic force microscope, in-situ microscopic morphology monitoring of the metal-dielectric interface is achieved, accurately capturing the height change of the metal relative to the dielectric at different temperatures. Its measurement accuracy reaches the nanometer level, far exceeding traditional macroscopic measurement methods. In data processing, methods such as plane fitting and cross-sectional analysis are used to efficiently extract the height information of the metal region, and the thermal expansion coefficient is quickly calculated using a thermal expansion model. The entire process is highly automated, completing the process from heating to data analysis in a single step, significantly improving measurement efficiency while ensuring the accuracy and reliability of the results, effectively guaranteeing the quality control of hybrid bonding interfaces in semiconductor manufacturing. Attached Figure Description

[0063] Figure 1This is a flowchart illustrating the measurement of the coefficient of thermal expansion of metals in a mixed-bonded sample using an atomic force microscope heating module, as described in this invention.

[0064] Figure 2 This is a measurement image of the copper-silica morphology at room temperature in an application example.

[0065] Figure 3 This is a measurement image of the copper-silica morphology under gradient heating in an application example;

[0066] Figure 4 The graph shows the copper-silica height analysis at different temperatures in the application example. Detailed Implementation

[0067] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0068] Example 1

[0069] This embodiment utilizes an atomic force microscope heating module to measure the coefficient of thermal expansion of metals in a mixed-bonded sample. See the flowchart below. Figure 1 This includes the following steps:

[0070] Step 1: Construct a heating dynamics platform on an atomic force microscope;

[0071] In practice, in step one, the heating module is set up on the atomic force microscope. The specific steps include:

[0072] 11) After mounting the probe on the ceramic heating probe holder, mount the ceramic heating probe holder on the atomic force microscope scanner, and use the shading method to adjust the laser so that it hits the probe;

[0073] 12) Open the heating sample stage, close the atomic force microscope scanning control software, and, while ensuring that the power is off, install the pressure thermocouple, and then open the software;

[0074] 13) Mount the annular gas channel on the heated sample stage;

[0075] 14) Fix the sample to the sample tray with thermally conductive adhesive and place it on the magnetic surface of the pressure thermocouple;

[0076] 15) Assemble the fluid cooling system and thermal application controller and turn on the switch.

[0077] In specific implementation, in step one, the probe mentioned in 11) is a probe without a metal coating.

[0078] Step 2: Scan the metal-dielectric sample at room temperature to obtain initial morphology data;

[0079] Step 3: Perform gradient heating on the metal-dielectric sample and characterize its surface morphology;

[0080] Step four: Process the atomic force microscope scanning data;

[0081] Step 5: Based on the thermal expansion model, calculate the thermal expansion coefficient Δα of the metal relative to the dielectric using the following formula: Δl=Δl thermal expansion+Δl thermal strain=Δlz+ν(Δlx+Δly)=lΔαΔT+2dνΔαΔT=(l+2dν)ΔαΔT.

[0082] In specific implementation, in step two, the surface morphology of the mixed bonded sample is measured at room temperature. The specific steps include: at room temperature, after setting appropriate scanning parameters, scanning the sample surface containing the metal-dielectric region to obtain initial surface morphology data.

[0083] In specific implementation, in step three, the mixed bonded sample is subjected to gradient heating and its morphology is characterized. The specific steps include: heating the sample in segments by setting a temperature gradient, and measuring the surface morphology after maintaining a constant temperature in each target temperature segment for a predetermined time; after characterizing the highest temperature node, cooling it to the ambient temperature, and performing surface morphology characterization again after maintaining a constant temperature for a predetermined time.

[0084] In specific implementation, in step three, during the entire heating and measurement process, one or more inert or reducing gases are continuously introduced into the sample surface through an annular gas channel to suppress oxidation of the metal surface during heating.

[0085] In practice, in step three, the flow rate of the introduced gas needs to be controlled to ensure that the sample is heated in a completely oxygen-free environment.

[0086] In specific implementation, step four involves data processing of the characterization results from step three. The specific steps include:

[0087] After performing planar fitting on the scanned images in the atomic force microscopy data processing software, the height of the metal region relative to the surrounding dielectric is obtained through cross-sectional analysis, and the changes in the height of the metal relative to the dielectric are compared at different temperatures.

[0088] In specific implementation, in step five, the thermal expansion coefficient of the metal in the mixed-bonded sample is calculated. The height of the metal relative to the dielectric at different temperatures obtained in step four is substituted into the formula: Δl=Δl thermal expansion+Δl thermal strain=Δlz+ν(Δlx+Δly)=lΔαΔT+2dνΔαΔT=(l+2dν)ΔαΔT. This calculates the thermal expansion coefficient mismatch value Δα of the metal relative to the dielectric, where Δlx, Δly, and Δlz are the expansions along the x, y, and z axes, respectively; ν is the Poisson's ratio of the metal; l is the initial height of the metal via; d is the diameter of the metal via; and Δα is the thermal expansion coefficient mismatch value (α) of the metal relative to the dielectric. 金属 -α 电介质 ), which is the coefficient of thermal expansion of the metal relative to the dielectric Δα.

[0089] In specific implementation, the process of measuring the initial height l and diameter d of the metal through-hole in the acquired initial morphology data includes:

[0090] Open the initial morphology data in the atomic force microscopy analysis software;

[0091] Geometric features of the metal through-hole region are extracted using topographic data analysis tools.

[0092] The height analysis function is used to measure the height difference between the top of the metal via and the substrate dielectric to determine the initial height l of the metal via;

[0093] Use a diameter measuring tool to measure the diameter d at the opening of the metal through hole.

[0094] In practice, step five includes the following steps:

[0095] The relative morphological changes of the extracted metal and dielectric are substituted into the calculation formula of the thermal expansion model:

[0096] Δl=(l+2dν)ΔαΔT;

[0097] Where Δl is the total deformation of the metal during thermal expansion, ν is the Poisson's ratio of the metal, l is the initial height of the metal through hole, d is the diameter of the metal through hole, Δα is the thermal expansion coefficient of the metal and the dielectric, and ΔT is the temperature change.

[0098] Solve the calculation formula of the thermal expansion model to obtain the thermal expansion coefficient Δα of the metal relative to the dielectric.

[0099] The process of obtaining the various parameters in the thermal expansion model specifically includes:

[0100] The initial height l and diameter d of the metal through hole are measured from the initial morphology data obtained from S2.

[0101] The Poisson's ratio ν of a metal can be obtained from its known properties or by querying a materials database.

[0102] The temperature change ΔT is determined from the temperature data recorded during the gradient heating process of S3;

[0103] Δl was obtained by comparing the relative morphological changes of the metal and dielectric at different temperatures in S4.

[0104] In specific implementation, the process of measuring the initial height l and diameter d of the metal through-hole from the initial morphology data obtained from S2 includes:

[0105] Open the initial morphology data in the atomic force microscopy analysis software;

[0106] Geometric features of the metal through-hole region are extracted using topographic data analysis tools.

[0107] The height analysis function is used to measure the height difference between the top of the metal via and the substrate dielectric to determine the initial height l of the metal via;

[0108] Use a diameter measuring tool to measure the diameter d at the opening of the metal through hole.

[0109] In specific implementation, the process of obtaining Δl by comparing the relative morphological changes of the metal and dielectric at different temperatures in S4 includes:

[0110] The topographic data obtained by scanning at different temperatures are aligned with the topographic data at the initial temperature in the same spatial coordinate system;

[0111] Multiple measurement points were marked at the center of the metal via and in the surrounding dielectric area.

[0112] Using the cross-sectional analysis function of atomic force microscopy software, the height difference between the metal surface and the dielectric surface at the same location point was measured and recorded along the vertical direction.

[0113] The metal-dielectric height difference at the initial temperature is used as a reference;

[0114] Subtracting the baseline value from the height difference at each target temperature yields multiple Δl values, which are then used to calculate Δα.

[0115] Specifically, this embodiment utilizes an atomic force microscope (AFM) heating module to achieve oxygen-free heating and morphology characterization of metal-dielectric samples. Its core mechanism lies in precisely controlling the gas environment during heating and real-time monitoring of sample surface morphology changes. During heating, an annular gas channel is mounted on the heating sample stage, and a high-purity inert gas (such as nitrogen) or reducing gas is introduced into it to replace the surrounding air, creating an oxygen-free measurement environment. This oxygen-free environment effectively isolates oxygen from contact with the metal sample, fundamentally preventing oxidation reactions at high temperatures and ensuring the chemical stability of the metal sample during heating. Simultaneously, the AFM probe scans the sample surface with extremely high resolution. During heating, the metal and dielectric exhibit different morphological changes due to their different coefficients of thermal expansion. The probe can capture these minute changes in real time and convert them into electrical signals. Subsequent data processing and analysis of these signals yield information on the relative morphological changes of the metal and dielectric at different temperatures, providing fundamental data support for the accurate calculation of the coefficient of thermal expansion.

[0116] Specifically, this embodiment calculates the coefficient of thermal expansion Δα of the metal relative to the dielectric based on a thermal expansion model. This model is constructed based on the physical laws of material thermal expansion. When a material is heated, the thermal motion of its internal atoms or molecules intensifies, leading to volume expansion. For a composite structure composed of a metal and a dielectric, the thermal expansion behavior of the metal under a temperature change ΔT can be described from two dimensions: axial and transverse. Axial thermal expansion is mainly manifested as the height change Δlz of the metal through-hole in the vertical direction (z-axis), which is due to the cumulative displacement of metal atoms along the vertical direction. Transverse thermal expansion is manifested as the volume expansion of the metal in the horizontal plane (x-axis and y-axis directions), which is affected by the metal's Poisson's ratio ν. Poisson's ratio reflects the ratio of transverse strain to longitudinal strain when the material is subjected to transverse force. According to the thermal expansion model formula Δl=Δlthermal expansion+Δlthermal strain=Δlz+ν(Δlx+Δly)=lΔαΔT+2dνΔαΔT=(l+2dν)ΔαΔT, where l is the initial height of the metal via and d is the diameter of the metal via. By processing the atomic force microscopy scanning data, the height change Δl of the metal relative to the dielectric can be obtained. Combined with the known initial geometric parameters l and d, and the Poisson's ratio ν of the metal (which can be queried from a material database or experimentally determined), the mismatch value of the thermal expansion coefficient Δα of the metal relative to the dielectric (i.e., the thermal expansion coefficient Δα of the metal relative to the dielectric that needs to be calculated in this invention) can be calculated. This model calculation process considers the interaction between the metal and the dielectric and the influence of geometric dimensions on thermal expansion, thereby achieving accurate quantification of the metal's thermal expansion coefficient, providing key theoretical basis and data support for the height control of the metal and dielectric in hybrid bonding technology.

[0117] Application Example 1

[0118] This embodiment provides a method for measuring the coefficient of thermal expansion of metals in a mixed-bonded sample using an atomic force microscope heating module, including the following steps:

[0119] Step 1: Construct a heating dynamics platform on an atomic force microscope;

[0120] Step one includes:

[0121] 11) After mounting the probe on the ceramic heating probe holder, mount the ceramic heating probe holder on the atomic force microscope scanner, and use the shading method to adjust the laser so that it hits the probe;

[0122] The probe is a probe without a metal coating;

[0123] 12) Open the heating sample stage, close the atomic force microscope scanning control software, and, while ensuring that the power is off, install the pressure thermocouple, and then open the software;

[0124] 13) Mount the annular gas channel on the heated sample stage;

[0125] 14) Fix the sample to the sample tray with thermally conductive double-sided tape and place it on the magnetic suction surface of the pressure thermocouple;

[0126] 15) Assemble the fluid cooling system and thermal application controller and turn on the switch.

[0127] Step 2: Scan the copper-silica sample at room temperature to obtain initial morphology data;

[0128] At 25℃, with a resolution of 512×512 and a scan rate of 1Hz, the surface region of the copper-silica sample was scanned to obtain initial surface morphology data, such as... Figure 2 As shown.

[0129] Step 3: Gradient heating is applied to the copper-silica sample and the surface morphology is characterized.

[0130] The copper-silica sample was heated in stages to 100℃, 150℃, and 200℃ at a heating rate of 50℃-75℃ / stage. After each stage of heating, the temperature was held at ±0.1℃ for 10 minutes before surface morphology measurement. After characterizing the copper-silica sample at 200℃, it was cooled to room temperature and held at ±0.1℃ for 10 minutes before the surface morphology was characterized again. Figure 3 The images shown are atomic force microscope (AFM) images at 100℃ (top left), 150℃ (top right), 200℃ (bottom left), and finally cooled to room temperature (bottom right).

[0131] Throughout the heating and measurement process, nitrogen gas was continuously introduced into the sample surface through an annular gas channel to suppress oxidation of the copper surface during heating. The flow rate of nitrogen gas was controlled at 50 mL / min.

[0132] Step four: Process the atomic force microscope scanning data;

[0133] After performing planar fitting processing on the scanned images in the atomic force microscopy data processing software, the height of the copper region relative to the surrounding silica was obtained through cross-sectional analysis. The changes in the relative height of copper to silica at different temperatures were then compared. Figure 4 The figure shown is a schematic diagram of the cross-sectional height of copper-silicon dioxide at different temperatures.

[0134] Step 5: Based on the thermal expansion model, calculate the linear thermal expansion coefficient using the following formula: α=ΔL / (L0*ΔT), where ΔL is the change in length, L0 is the initial length, and ΔT is the change in temperature.

[0135] Substituting the height of copper relative to silicon dioxide dielectric obtained in step four at different temperatures into the formula: Δl=Δl thermal expansion+Δl thermal strain=Δlz+ν(Δlx+Δly)

[0136] =lΔαΔT+2dνΔαΔT=(l+2dν)ΔαΔT, calculate the thermal expansion mismatch value Δα of copper relative to silicon dioxide. From 25℃ to 100℃, Δl is approximately 10nm, and Δα is approximately 43.9ppm / ℃; from 100℃ to 150℃, Δl is approximately 10nm, and Δα is approximately 65.8ppm / ℃; from 150℃ to 200℃, Δl is approximately 30nm, and Δα is approximately 197ppm / ℃.

[0137] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for measuring the coefficient of thermal expansion of a metal in a mixed-bonded sample using an atomic force microscope heating module, characterized in that, Includes the following steps: S1. Construct a heating mechanics platform on an atomic force microscope; S2. Based on the heating mechanics platform built in S1, scan the metal-dielectric sample at room temperature to obtain initial morphology data; S3. Using the heating mechanics platform built in S1, the metal-dielectric sample was subjected to gradient heating in an oxygen-free environment, and the surface morphology was characterized in real time during the heating process. S4. The data obtained from gradient heating and morphology characterization in S3 are processed to extract the relative morphological change information of the metal and dielectric. S5. Based on the initial morphology data obtained in S2 and the relative morphology change information extracted in S4, substitute the relative morphology change between the metal and the dielectric extracted in step S4 into the calculation formula of the thermal expansion model: Δl = (l + 2dν)ΔαΔT; Where Δl is the total deformation of the metal during thermal expansion, ν is the Poisson's ratio of the metal, l is the initial height of the metal through hole, d is the diameter of the metal through hole, Δα is the coefficient of thermal expansion of the metal relative to the dielectric, and ΔT is the temperature change. Solve the calculation formula of the thermal expansion model to obtain the thermal expansion coefficient Δα of the metal relative to the dielectric.

2. The method for measuring the coefficient of thermal expansion of metals in a mixed-bonded sample using an atomic force microscope heating module according to claim 1, characterized in that, S1 specifically includes the following steps: After loading the probe onto the ceramic heating probe holder, the ceramic heating probe holder is installed on the atomic force microscope scanner, and the laser is adjusted onto the probe using the shading method. Activate the heated sample stage, close the atomic force microscope scanning control software and disconnect the power, install the pressure thermocouple, and then reopen the atomic force microscope scanning control software. Install the annular gas channel on the heated sample stage; Use thermally conductive adhesive to fix the sample in the sample tray and place it on the magnetic suction surface of the pressure thermocouple; Assemble and turn on the fluid cooling system and thermal application controller.

3. The method for measuring the coefficient of thermal expansion of metals in a mixed-bonded sample using an atomic force microscope heating module according to claim 2, characterized in that, In S1, the probe is a probe without a metal coating.

4. The method for measuring the coefficient of thermal expansion of metals in a mixed-bonded sample using an atomic force microscope heating module according to claim 1, characterized in that, S2 specifically includes the following steps: Under normal temperature conditions, set the scanning parameters of the atomic force microscope, including scanning range, resolution and scanning rate; Bring the probe close to the surface of the metal-dielectric sample and begin scanning; Record and save the initial topographic data obtained from the scan, including the height information of the metallic and dielectric regions.

5. The method for measuring the coefficient of thermal expansion of a metal in a mixed-bonded sample using an atomic force microscope heating module according to claim 1, characterized in that, S3 specifically includes the following steps: Set a temperature gradient and gradually heat the sample from room temperature to multiple target temperature points in an oxygen-free environment. Maintain a constant temperature at each target temperature for a preset time to ensure uniform sample temperature; Under constant temperature conditions, the surface morphology of the sample was scanned using an atomic force microscope, and morphology data at different temperatures were recorded. After heating and scanning at all temperature points are completed, turn off the heating module and allow the sample to cool naturally to room temperature.

6. The method for measuring the coefficient of thermal expansion of a metal in a mixed-bonded sample using an atomic force microscope heating module according to claim 1, characterized in that, S4 specifically includes the following steps: The scan data acquired in S3 is preprocessed, including noise removal and data drift correction; Plane fitting is performed on the preprocessed data to eliminate the influence of probe tilt on the measurement results; The height difference data between the metal region and the surrounding dielectric region was extracted using cross-sectional analysis tools. The extracted height difference data is compared and analyzed with the initial morphology data obtained in step S2 to calculate the relative morphological changes of the metal and dielectric at different temperatures.

7. The method for measuring the coefficient of thermal expansion of a metal in a mixed-bonded sample using an atomic force microscope heating module according to claim 1, characterized in that, In S5, the process of obtaining the various parameters in the thermal expansion model specifically includes: The initial height l and diameter d of the metal through hole are measured from the initial topography data obtained from S2. The Poisson's ratio ν of a metal can be obtained from its known properties or by querying a materials database. The temperature change ΔT is determined from the temperature data recorded during the gradient heating process of S3; Δl was obtained by comparing the relative morphological changes of the metal and dielectric at different temperatures in S4.

8. The method for measuring the coefficient of thermal expansion of a metal in a mixed-bonded sample using an atomic force microscope heating module according to claim 7, characterized in that, The specific process of measuring the initial height l and diameter d of the metal through hole from the initial topography data obtained from S2 includes: Open the initial morphology data in the atomic force microscopy analysis software; Geometric features of the metal through-hole region are extracted using topographic data analysis tools. The height analysis function is used to measure the height difference between the top of the metal via and the substrate dielectric to determine the initial height l of the metal via; Use a diameter measuring tool to measure the diameter d at the opening of the metal through hole.

9. A method for measuring the coefficient of thermal expansion of a metal in a mixed-bonded sample using an atomic force microscope heating module according to claim 7, characterized in that, The specific process of obtaining Δl by comparing the relative morphological changes of the metal and dielectric at different temperatures in S4 includes: The topographic data obtained by scanning at different temperatures are aligned with the topographic data at the initial temperature in the same spatial coordinate system; Multiple measurement points were marked at the center of the metal via and in the surrounding dielectric area. Using the cross-sectional analysis function of atomic force microscopy software, the height difference between the metal surface and the dielectric surface at the same location point was measured and recorded along the vertical direction. The metal-dielectric height difference at the initial temperature is used as a reference; Subtracting the baseline value from the height difference at each target temperature yields multiple Δl values.

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