Interconnection structure impedance measurement circuit, measuring device and measuring method

Abstract

This disclosure provides an interconnect structure impedance measurement circuit. By optimizing the Wheatstone bridge structure, it employs three parallel branches. In one branch, the interconnect structure to be measured is connected in series. In the other two branches, two resistors are connected in series. By controlling the branch containing the interconnect structure and one of the other two branches to be simultaneously turned on, the voltage between the two turned-on branches is measured. The impedance of the two interconnect structures is calculated based on the current flowing into the interconnect structure impedance measurement circuit, the measured voltage, and the resistance in the branches. This disclosure allows for convenient, large-scale, and accurate measurement of interconnect structure impedance, and enables real-time and accurate monitoring of the impedance of a single interconnect structure in reliability experiments. This disclosure also provides an interconnect structure impedance measurement device and method.

Description

Technical Field

[0001] This disclosure relates to the fields of circuit testing technology and reliability testing technology, specifically to an interconnect structure impedance measurement circuit, measuring device and measuring method. Background Technology

[0002] Accurate measurement of minute resistance has always been a focus of attention in many industries, especially for interconnect wires and solder joints. Precise resistance measurement plays a crucial role in evaluating the performance of the entire system and the quality of the solder joints. However, for the reliability evaluation of single interconnect structures, taking electromigration testing as an example, there is still a lack of effective methods to accurately monitor the resistance of single solder joint structures during long-term aging tests.

[0003] To accurately measure the resistance of various small structures such as interconnect metal wires, researchers have proposed several approaches and methods. The four-point probe method is a recognized accurate measurement method, but it still has some drawbacks in application, such as the inability to measure resistance in real-time on a large scale, its complexity, high cost, and the inconvenience of manual measurement. The classic Wheatstone bridge structure can also be used to measure minute resistances, but it has many limitations. It requires knowledge of three resistors and the selection of appropriate resistors to balance the bridge. The unknown resistor is obtained by solving a system of equations, which is difficult to meet and limits its application scenarios. Therefore, there is an urgent need for a device or method that can accurately measure the impedance of interconnect structures on a large scale, automatically, and easily. Summary of the Invention

[0004] This disclosure provides an interconnect structure impedance measurement circuit, measurement device, and measurement method.

[0005] In a first aspect, embodiments of this disclosure provide an interconnect structure impedance measurement circuit, comprising: a first branch, a second branch, and a third branch connected in parallel, wherein the first branch comprises a first interconnect structure, a second interconnect structure, and a first switch connected in series, the second branch comprises a first resistor, a second resistor, and a second switch connected in series, and the third branch comprises a third resistor, a fourth resistor, and a third switch connected in series.

[0006] The impedance of the first interconnect structure and the impedance of the second interconnect structure are determined based on the first voltage between the first branch and the second branch, the second voltage between the first branch and the second branch, the first resistor, the second resistor, the third resistor, the fourth resistor, and the first current input to the impedance measurement circuit of the interconnect structure.

[0007] The first voltage is detected when the first switch and the second switch are closed and the third switch is open, and the second voltage is detected when the first switch and the third switch are closed and the second switch is open.

[0008] In some embodiments, the resistance value of the first resistor is not equal to the resistance value of the third resistor, and the resistance value of the second resistor is not equal to the resistance value of the fourth resistor.

[0009] In some embodiments, the first interconnect structure and the second interconnect structure are connected to a printed circuit board (PCB), and the interconnect structure impedance measurement circuit is disposed on the PCB, or the interconnect structure impedance measurement circuit is disposed on an interconnect structure impedance measurement device.

[0010] In some embodiments, the first interconnect structure is at least two fifth resistors connected in parallel, wherein the resistance values ​​of the fifth resistors are the same and are equal to the resistance values ​​of the second interconnect structure; or, the first interconnect structure is a wire.

[0011] In some embodiments, the first interconnection structure consists of n fifth resistors connected in parallel, where n is an integer greater than or equal to 2; the resistance of the second resistor is n times the resistance of the first resistor, and the resistance of the fourth resistor is n times the resistance of the third resistor.

[0012] In another aspect, embodiments of this disclosure also provide an interconnect structure impedance measurement device, including: a constant current source, a voltage detection module, a control module, and an interconnect structure impedance measurement circuit as described above. The constant current source is connected to the first branch, the second branch, and the third branch, and is used to provide a first current to the interconnect structure impedance measurement circuit when the first switch and the second switch are closed and the third switch is open, or when the first switch and the third switch are closed and the second switch is open.

[0013] The voltage detection module is connected to the first branch, the second branch, and the third branch respectively, and is used to detect a first voltage between the first branch and the second branch when the first switch and the second switch are closed and the third switch is open; and to detect a second voltage between the first branch and the second branch when the first switch and the third switch are closed and the second switch is open.

[0014] The control module is used to control the constant current source to provide the first current to the interconnect structure impedance measurement circuit, and to control the first switch, the second switch and the third switch to open or close; and to acquire the first voltage and the second voltage detected by the voltage detection module, and to calculate the impedance of the first interconnect structure and the impedance of the second interconnect structure based on the first resistor, the second resistor, the third resistor, the fourth resistor, the first voltage, the second voltage and the first current.

[0015] In some embodiments, the interconnect structure impedance measurement circuit is the interconnect structure impedance measurement circuit as described above.

[0016] The constant current source is also used to provide a second current to the interconnect structure impedance measurement circuit when the first switch is closed and the second and third switches are open, wherein the second current is greater than the first current.

[0017] In another aspect, embodiments of this disclosure also provide an interconnect structure impedance measurement method, applied to the interconnect structure impedance measurement device as described above, the method comprising:

[0018] Provide a first current to the impedance measurement circuit of the interconnect structure;

[0019] The interconnection structure impedance measurement circuit is controlled to be in a first state to detect a first voltage between the first branch and the second branch; wherein, in the first state, the first switch and the second switch are closed and the third switch is open;

[0020] The interconnection structure impedance measurement circuit is controlled to switch from the first state to the second state to detect the second voltage between the first branch and the third branch; wherein, in the second state, the first switch and the third switch are closed and the second switch is open;

[0021] Stop supplying a first current to the impedance measurement circuit of the interconnect structure, and calculate the impedance of the first interconnect structure and the second interconnect structure based on the first resistor, the second resistor, the third resistor, the fourth resistor, the first voltage, the second voltage, and the first current.

[0022] In another aspect, embodiments of this disclosure also provide an interconnect structure impedance measurement method, applied to the interconnect structure impedance measurement device as described above, the method comprising:

[0023] The impedance of the second interconnect structure was measured using the method described above;

[0024] The interconnect structure impedance measurement circuit is controlled to switch from the second state to the third state, in which the first switch is closed and the second switch and the third switch are open;

[0025] A second current is provided to the impedance measurement circuit of the interconnect structure within a preset time period to increase the current stress and accelerate the degradation of the interconnect structure;

[0026] The impedance of the second interconnect structure is measured using the method described above, and compared with a preset failure impedance value until the impedance of the second interconnect structure reaches the failure impedance value, at which point the measurement ends.

[0027] In some embodiments, the method further includes:

[0028] Record the failure time from the start of providing the second current to the end of the measurement;

[0029] The reliability of the second interconnect structure is analyzed based on the failure time.

[0030] The interconnect structure impedance measurement circuit provided in this disclosure optimizes the Wheatstone bridge structure by using three parallel branches. In one branch, the interconnect structure to be measured is connected in series, and in the other two branches, two resistors are connected in series. By controlling the branch of the interconnect structure and one of the other two branches to be turned on simultaneously, the voltage between the two turned-on branches is measured. The impedance of the two interconnect structures is calculated based on the current flowing into the interconnect structure impedance measurement circuit, the measured voltage, and the resistance in the branch. This disclosure embodiment can conveniently and accurately measure the impedance of interconnect structures on a large scale, and can accurately monitor the impedance of a single interconnect structure in real time during reliability experiments. Attached Figure Description

[0031] Figure 1 A schematic diagram of an interconnect structure impedance measurement circuit provided in an embodiment of this disclosure;

[0032] Figure 2 for Figure 1 A schematic diagram of the physical structure of the measurement circuit;

[0033] Figure 3 A circuit diagram for measuring resistance using a traditional Wheatstone bridge;

[0034] Figure 4 A schematic diagram of an interconnect structure impedance measurement circuit provided in yet another embodiment of this disclosure;

[0035] Figure 5 for Figure 4 A schematic diagram of the physical structure of the measurement circuit;

[0036] Figure 6A schematic diagram of the measurement circuit packaged on a measurement device according to an embodiment of this disclosure;

[0037] Figure 7 A schematic diagram of the measurement circuit packaged on a PCB according to an embodiment of this disclosure;

[0038] Figure 8 This is a schematic diagram of the interconnect structure impedance measuring device provided in the embodiments of this disclosure;

[0039] Figure 9 A schematic diagram of the interconnect structure impedance measuring device provided in yet another embodiment of this disclosure;

[0040] Figure 10 This is a schematic flowchart of the interconnect structure impedance measurement method provided in the embodiments of this disclosure;

[0041] Figure 11 This is a schematic flowchart of an interconnect structure impedance measurement method provided in yet another embodiment of the present disclosure. Detailed Implementation

[0042] Exemplary embodiments will be described more fully below with reference to the accompanying drawings; however, these exemplary embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will enable those skilled in the art to fully understand the scope of this disclosure.

[0043] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0044] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the said feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded.

[0045] The embodiments described herein can be described with reference to plan views and / or cross-sectional views using the ideal schematic diagrams of this disclosure. Therefore, the example illustrations can be modified according to manufacturing techniques and / or tolerances. Therefore, the embodiments are not limited to those shown in the drawings, but include modifications to configurations formed based on manufacturing processes. Therefore, the areas illustrated in the drawings are schematic in nature, and the shapes of the areas shown in the figures illustrate specific shapes of areas of an element, but are not intended to be limiting.

[0046] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted as having an idealized or overly formal meaning, unless expressly so defined herein.

[0047] For interconnect wires and solder joints, accurately measuring their resistance has always been a major challenge in the industry due to their tiny structures and the high conductivity of metals. In reliability testing, interconnect structures are also a key focus. Under long-term temperature / current stress, the degree of degradation or failure of interconnect structures is often determined by changes in their resistance. Since the resistance of interconnect structures is extremely small, these changes are negligible. Therefore, real-time and accurate monitoring of interconnect impedance is crucial for reliability testing. The four-point probe method for accurately measuring interconnect wires and solder joints offers the highest accuracy, but the measurement process is complex, it cannot monitor resistance in real time, and it is costly. The classic Wheatstone bridge can measure resistance relatively accurately, but it requires knowledge of three of the resistor values, limiting its practicality and hindering large-scale application.

[0048] To address the aforementioned problems, embodiments of this disclosure provide an interconnect structure impedance measurement circuit, such as... Figure 1 As shown, the interconnect structure impedance measurement circuit includes a first branch, a second branch, and a third branch connected in parallel. The first branch includes a first interconnect structure, a second interconnect structure, and a first switch K1 connected in series. The second branch includes a first resistor R1, a second resistor R2, and a second switch K2 connected in series. The third branch includes a third resistor R1', a fourth resistor R2', and a third switch K3 connected in series.

[0049] The impedance R3 of the first interconnection structure and the impedance R4 of the second interconnection structure are determined based on the first voltage Vg between the first branch and the second branch, the second voltage Vg' between the first branch and the third branch, the first resistor R1, the second resistor R2, the third resistor R1', the fourth resistor R2', and the first current I of the input interconnection structure impedance measurement circuit.

[0050] The first voltage Vg is detected when the first switch K1 and the second switch K2 are closed and the third switch K3 is open, and the second voltage Vg' is detected when the first switch K1 and the third switch K3 are closed and the second switch K2 is open.

[0051] The interconnect structure impedance measurement circuit provided in this disclosure optimizes the Wheatstone bridge structure by using three parallel branches. In one branch, the interconnect structure to be measured is connected in series, and in the other two branches, two resistors are connected in series. By controlling the branch of the interconnect structure and one of the other two branches to be turned on simultaneously, the voltage between the two turned-on branches is measured. The impedance of the two interconnect structures is calculated based on the current flowing into the interconnect structure impedance measurement circuit, the measured voltage, and the resistance in the branch. This disclosure embodiment can conveniently and accurately measure the impedance of interconnect structures on a large scale, and can accurately monitor the impedance of a single interconnect structure in real time during reliability experiments.

[0052] Figure 2 for Figure 1 The diagram shows the physical structure of the interconnect impedance measurement circuit. Figure 2 As shown, the first interconnect structure and the second interconnect structure are connected to the PCB (Printed Circuit Board) and the integrated circuit chip substrate, respectively, for example, they can be connected by BGA Ball (Ball Grid Array Package solder ball).

[0053] Figure 3 This is a circuit diagram for measuring resistance using a traditional Wheatstone bridge. Figure 3 As shown, the resistance values ​​of R1, R2, and R3 are known, and R4 is the resistor to be measured. G is a galvanometer. When the galvanometer pointer points to zero, the bridge is balanced, and the resistance value of R4 can be calculated by R1*R4 = R2*R3.

[0054] Combination Figure 1 and Figure 2 As shown, R3 is the impedance of the first interconnection structure, R4 is the impedance of the second interconnection structure, R1 and R2 are known resistors, and R1' and R2' are known resistors. I is the input current, Vg is the voltage difference between node 3 and node 4, and Vg' is the voltage difference between node 3 and node 4'. Through multiple iterations, the values ​​of the impedance R3 of the first interconnection structure and the impedance R4 of the second interconnection structure can be calculated by solving a system of nonlinear equations.

[0055] According to Kirchhoff's laws, we can obtain:

[0056]

[0057]

[0058]

[0059]

[0060] Where R is the resistance of the second branch and R' is the resistance of the third branch.

[0061] Combining the above formulas (1), (2), (3), and (4), we get:

[0062]

[0063]

[0064] It should be noted that there are no strict requirements for the selection of the resistance values ​​of the four resistors R1, R2, R1', and R2'. However, in scenarios involving the measurement of the impedance of minute structures, the measurement accuracy can be further improved by controlling R1 / R2 to be approximately equal to R1' / R2'.

[0065] In some embodiments, the resistance value of the first resistor R1 is not equal to the resistance value of the third resistor R1', and the resistance value of the second resistor R2 is not equal to the resistance value of the fourth resistor R2'.

[0066] This disclosure can be applied to multiple technical fields such as electronic packaging, reliability testing, and precision measurement. In the electronic packaging manufacturing process, there are numerous soldering interconnection scenarios, and the quality of the interconnect structure directly affects the product quality. Therefore, the importance of quickly assessing the soldering quality of interconnect structures is self-evident. Poor soldering is reflected in increased resistance. The interconnect structure impedance measurement circuit of this disclosure can quickly detect the impedance of the interconnect structure, serving as a detection tool for real-time monitoring of changes in the manufacturing process. Similarly, throughout the entire chip manufacturing process, the resistance of interconnect structures is often difficult to determine due to contact resistance. The interconnect structure impedance measurement circuit of this disclosure can also quickly and accurately measure the impedance of micro-interconnect structures, which has significant application value for evaluating the performance of the entire system.

[0067] In reliability testing, it is often necessary to continuously monitor changes in impedance values. Therefore, the interconnect structure impedance measurement circuit of the present disclosure embodiments can be improved to achieve single interconnect structure impedance monitoring in reliability experiments.

[0068] In some embodiments, the impedance R3 of the first interconnect structure is in milliohms. That is, the first interconnect structure in the interconnect structure impedance measurement circuit is set to be an interconnect structure with a smaller impedance, thereby forming a single interconnect structure including the second interconnect structure in the first branch.

[0069] The first interconnect structure with low impedance can be implemented in various ways. For example, the first interconnect structure can be at least two fifth resistors connected in parallel, each fifth resistor having the same resistance value, and the resistance value of the fifth resistors being equal to the resistance value of the second interconnect structure; alternatively, the first interconnect structure can also be implemented using wires.

[0070] In the embodiments disclosed herein, such as Figure 4 , 5 As shown, the first interconnect structure consists of three fifth resistors R5 connected in parallel. In practice, the number of fifth resistors R5 connected in parallel can be increased. The more fifth resistors R5 there are, the more accurate the measurement of the impedance of a single interconnect structure (i.e., the impedance R4 of the second interconnect structure) will be. It should be noted that the impedance R3 of the first interconnect structure is the impedance after all the fifth resistors are connected in parallel.

[0071] In some embodiments, when the first interconnect structure consists of n parallel-connected fifth resistors R5 (n being an integer greater than or equal to 2), the resistance of the second resistor R2 is n times the resistance of the first resistor R1, and the resistance of the fourth resistor R2' is n times the resistance of the third resistor R1'. That is, the selection of the resistance values ​​of the first resistor R1, the second resistor R2, the third resistor R1', and the fourth resistor R2' in the second and third branches is related to the number of fifth resistors R5 connected in parallel in the first interconnect structure. Figure 4 The diagram shows three fifth resistors R5 connected in parallel and then connected in series with another single interconnect structure (i.e., the second interconnect structure R4). The impedance of the second interconnect structure R4 is approximately three times the impedance of the three fifth resistors R5.

[0072] Figure 6 and Figure 7 These are two application scenarios for the interconnect structure impedance measurement circuit. Different measurement methods can be used to meet different measurement requirements. Figure 6 and Figure 7 Two measurement design schemes.

[0073] like Figure 6 As shown, the interconnect structure impedance measurement circuit is packaged on the interconnect structure impedance measurement device. The PCB is connected to the interconnect structure impedance measurement device through the first interconnect structure and the second interconnect structure. The impedance of the two interconnect structures is measured by the interconnect structure impedance measurement device. Figure 6 The scenario shown has a relatively simple PCB layout design and saves space, but it places high demands on the impedance measurement device for the interconnect structure.

[0074] like Figure 7 As shown, the interconnect structure impedance measurement circuit is integrated onto the PCB board. When measuring the impedance R3 of the first interconnect structure and the impedance R4 of the second interconnect structure, the interconnect structure impedance measurement device only needs to provide current. Figure 7 The scenario shown demonstrates that while the measurement system is simple to set up and easy to measure, it increases the difficulty of PCB layout design, increases layout consumption, and raises costs.

[0075] This disclosure also provides an interconnect structure impedance measurement device, such as... Figure 8As shown, it includes: a constant current source (A), a voltage detection module (V), a control module, and an interconnect structure impedance measurement circuit. The interconnect structure impedance measurement circuit is as follows: Figure 1 The interconnect structure impedance measurement circuit is shown.

[0076] The constant current source is connected to the first branch, the second branch and the third branch, and is used to provide a first current to the interconnect structure impedance measurement circuit when the first switch K1 and the second switch K2 are closed and the third switch K3 is open, or when the first switch K1 and the third switch K3 are closed and the second switch K2 is open.

[0077] The voltage detection module is connected to the first branch, the second branch and the third branch respectively, and is used to detect the first voltage Vg between the first branch and the second branch when the first switch K1 and the second switch K2 are closed and the third switch K3 is open; and to detect the second voltage Vg' between the first branch and the second branch when the first switch K1 and the third switch K3 are closed and the second switch K2 is open.

[0078] The control module is used to control the constant current source to provide a first current to the interconnect structure impedance measurement circuit, and to control the first switch K1, the second switch K2 and the third switch K3 to open or close; and to acquire the first voltage Vg and the second voltage Vg' detected by the voltage detection module, and to calculate the impedance R3 of the first interconnect structure and the impedance R4 of the second interconnect structure based on the first resistor R1, the second resistor R2, the third resistor R1', the fourth resistor R2', the first voltage Vg, the second voltage Vg' and the first current.

[0079] The interconnection structure impedance measurement device includes a constant current source, two voltmeters, three switches, two interconnection structures, and four resistors. The two interconnection structures are the resistors to be measured (R3, R4), and the resistance values ​​of the four resistors (R1, R2, R1', R2') are known. There are three parallel branches. The first branch includes a first switch K1, a first interconnection structure, and a second interconnection structure. The second branch includes a second switch K2 and two fixed resistors R1 and R2. The third branch includes a third switch K3 and two fixed resistors R1' and R2'. The voltmeter V is connected to the first and second branches, and also to the first and third branches. When measuring the impedances R3 and R4 of the interconnect structure, the first current provided by the constant current source is connected, and the first voltage Vg and the second voltage Vg' are obtained by measurement. Substituting them into the above formulas (5) and (6), the impedances R3 of the first interconnect structure and R4 of the second interconnect structure can be calculated simultaneously. The control module controls the switches (K1, K2, K3) to open and close, so as to realize the real-time monitoring of the impedances R3 of the first interconnect structure and R4 of the second interconnect structure.

[0080] The principle of real-time monitoring of interconnect structure impedance can also be applied to the accurate measurement of the impedance of microstructure resistors. The measurement of the impedance of microstructure resistors does not require real-time switching of the control module. The core circuit structure is basically the same. It is to measure Vg and Vg' and substitute them into formulas (5) and (6) to find R3 and R4. The direct measurement of the impedance is changed to the measurement of voltage and the use of formulas to obtain the resistance, thereby improving its accuracy. Among them, the resistance values ​​of the four resistors R1, R2, R1' and R2' can be selected by controlling R1 / R2≈R1' / R2', which further improves the measurement accuracy.

[0081] In some embodiments, such as Figure 9 As shown, the impedance measurement circuit of the interconnect structure is as follows: Figure 4 In the case of the interconnect structure impedance measurement circuit shown, the constant current source is also used to provide a second current to the interconnect structure impedance measurement circuit when the first switch K1 is closed and the second switch K2 and the third switch K3 are open, wherein the second current is greater than the first current. That is, the constant current source provides current stress in the power supply mode, in which the first branch is open and the second and third branches are closed.

[0082] The interconnection structure impedance measurement device includes a constant current source, two voltmeters, three switches, an interconnection structure formed by three resistors (R5) connected in parallel, and four fixed resistors. The parallel resistors are of the same type and from the same batch to ensure their resistance values ​​are approximately equal. The resistance values ​​of the four fixed resistors (R1, R2, R1', R2') are known. The voltmeter V connects to the first and second branches, and also connects to the first and third branches. There are three parallel branches. The first branch includes a first switch K1, a first interconnection structure formed by multiple resistors connected in parallel, and a second interconnection structure (single interconnection structure). The second branch includes a second switch K2, two fixed resistors R1 and R2. The third branch includes a third switch K3, two fixed resistors R1' and R2', where R2' is approximately three times the value of R1'. The value selection rules are the same as for R1 and R2, but the values ​​of R1' and R2' are not exactly equal to the values ​​of R1 and R2. In this embodiment, the first interconnect structure is obtained by connecting three fifth resistors in parallel, i.e., n=3. Accordingly, R2' is about three times R1'. It should be noted that as long as n≥2, the impedance R4 of the second interconnect structure can be calculated by formula (5). The larger the value of n, the higher the measurement accuracy. When measuring the impedance of the single interconnect structure (i.e., the impedance R4 of the second interconnect structure) in the reliability test, the first interconnect structure and the second interconnect structure are placed in the aging test environment and connected to the second current provided by the constant current source. The first voltage Vg and the second voltage Vg' are measured and substituted into formula (5) to calculate the impedance R4 of the single interconnect structure. The impedance R4 of the single interconnect structure is monitored in real time by controlling the opening and closing of the switching circuit through the control module. When R4 reaches the failure judgment standard, the test is terminated, and the failure time of the single interconnect structure can be accurately obtained, thereby predicting the characteristic life of the entire component and system.

[0083] Reliability tests on interconnect structures accelerate their degradation by applying temperature / current stress. This degradation process is essentially a process of internal damage to the interconnect structure, such as the appearance of holes, fractures, and the formation of metal compounds. These damages all lead to an increase in the resistance of the interconnect structure. By measuring Vg and Vg' and substituting them into formulas (5) and (6), the impedance R3 of the first interconnect structure and the impedance R4 of the second interconnect structure can be calculated, thereby enabling the monitoring of the interconnect structure impedance. The first interconnect structure is implemented by connecting multiple resistors in parallel, which makes the current flowing through the first interconnect structure less than the current flowing through the second interconnect structure. Therefore, under current stress, the degradation of the first interconnect structure will be slower than that of the second interconnect structure. Assuming that three copper metal resistors are connected in parallel to form the first interconnect structure, the current density exponent is generally n = 2. According to the Black equation, the lifetime of the first interconnect structure is about 10 times that of a single interconnect structure. The changes in Vg and Vg' represent the degradation of R4, thus accurately determining the change in the impedance of a single interconnect structure, exploring the degradation of a single interconnect structure, accurately obtaining its failure time, and thus improving the accuracy of predicting the characteristic lifetime of components and the entire system.

[0084] This disclosure also provides a method for measuring the impedance of an interconnect structure, the method being applied to, for example... Figure 8 The aforementioned interconnect structure impedance measuring device, such as Figure 10 As shown, the interconnect structure impedance measurement method includes the following steps:

[0085] Step 11: Provide a first current to the interconnect structure impedance measurement circuit.

[0086] In this step, a constant current source provides the first current to the interconnect structure impedance measurement circuit.

[0087] Step 12: Control the interconnection structure impedance measurement circuit to a first state and detect the first voltage between the first branch and the second branch; wherein, in the first state, the first switch and the second switch are closed and the third switch is open.

[0088] In this step, the control module controls the closure of the first switch K1 and the second switch K2, and opens the third switch K3, and uses a voltmeter to measure the inter-bridge voltage Vg.

[0089] Step 13: Control the interconnection structure impedance measurement circuit to switch from the first state to the second state to detect the second voltage between the first branch and the third branch; wherein, in the second state, the first switch and the third switch are closed and the second switch is open.

[0090] In this step, the control module closes the first switch K1 and the third switch K3, opens switch K2, and uses a voltmeter to measure the inter-bridge voltage Vg'. In both the first and second states, the constant current source is in measurement mode.

[0091] Step 14: Stop supplying the first current to the interconnect structure impedance measurement circuit, and calculate the impedance of the first interconnect structure and the second interconnect structure based on the first resistor, the second resistor, the third resistor, the fourth resistor, the first voltage, the second voltage, and the first current.

[0092] In this step, the constant current source is turned off, and the control module solves for R3 and R4 using formulas (5) and (6).

[0093] This disclosure also provides an embodiment of an interconnect structure impedance measurement method for reliability testing, the method being applied to, for example... Figure 9 The interconnection structure impedance measurement device shown is as follows: Figure 11 As shown, the method includes the following steps:

[0094] Step 11: Provide a first current to the interconnect structure impedance measurement circuit.

[0095] Step 12: Control the interconnection structure impedance measurement circuit to a first state and detect the first voltage between the first branch and the second branch; wherein, in the first state, the first switch and the second switch are closed and the third switch is open.

[0096] Step 13: Control the interconnection structure impedance measurement circuit to switch from the first state to the second state to detect the second voltage between the first branch and the third branch; wherein, in the second state, the first switch and the third switch are closed and the second switch is open.

[0097] Step 14: Stop supplying the first current to the interconnect structure impedance measurement circuit, and calculate the impedance of the first interconnect structure and the second interconnect structure based on the first resistor, the second resistor, the third resistor, the fourth resistor, the first voltage, the second voltage, and the first current.

[0098] Step 15: Control the interconnect structure impedance measurement circuit to switch from the second state to the third state. In the third state, the first switch is closed and the second and third switches are open.

[0099] In this step, the control module controls the closure of the first switch K1 and the opening of the second switch K2 and the third switch K3.

[0100] Step 16: Provide a second current to the interconnect structure impedance measurement circuit within a preset time period to increase current stress and accelerate interconnect structure degradation.

[0101] In this step, the control module controls the constant current source to switch to power supply mode to provide the required current stress. In power supply mode, the current flowing through the first branch is larger than that in measurement mode.

[0102] Step 17: Measure the impedance of the second interconnect structure and compare it with the preset failure impedance value until the impedance of the second interconnect structure reaches the failure impedance value, then end the measurement.

[0103] The failure impedance value is the standard value for resistor failure. In this step, repeat steps 11-14 until the impedance of the second interconnect structure reaches the failure standard, at which point the measurement ends.

[0104] In some embodiments, the interconnect structure impedance measurement method further includes the following steps: recording the failure time from the start of providing the second current to the end of the measurement; and performing a reliability analysis on the second interconnect structure based on the failure time.

[0105] In reliability testing, it is often necessary to continuously monitor changes in resistance values. The interconnect structure impedance measurement scheme of this disclosure can not only measure the initial resistance value, but also accurately measure the minute impedance changes generated during the test. Based on the set failure criteria, the failure time can be accurately obtained, which is very important for reliability prediction and analysis.

[0106] In electromigration reliability testing, microelectronic products, especially interconnect structures, experience prolonged exposure to current stress during application. This stress can cause metal atoms to shift along the direction of electron movement, leading to failures such as voids and fractures in the interconnect structure. Consequently, the interconnect structure impedance increases, and open circuits may even occur, ultimately damaging the entire device or product. With the miniaturization of microelectronics, interconnect structure sizes are continuously shrinking, and current densities are constantly increasing, exacerbating electromigration. Therefore, electromigration reliability testing is becoming increasingly necessary before the application of actual products, and evaluating the electromigration reliability of single interconnect structures is paramount. Because single interconnect structures have low impedance, impedance changes are difficult to capture, significantly challenging the accuracy of electromigration reliability testing. The interconnect structure impedance measurement scheme of this disclosure not only measures the initial value of the single interconnect structure impedance but also accurately monitors impedance changes, thus solving the problems existing in single interconnect structure electromigration reliability testing.

[0107] This embodiment of the invention enables the monitoring of the impedance of a single interconnect structure in a reliability experiment, as well as the real-time monitoring of the impedance of the interconnect structure and the measurement of minute resistances. The interconnect structure impedance measurement circuit is the core component for achieving accurate measurement. The sample is connected to the interconnect structure impedance measurement circuit, powered by a constant current source, and the voltage difference between branches is measured by a voltmeter. After another voltage measurement iteration, the impedance of the sample under test can be calculated using formulas (5) and (6). The impedance of the interconnect structure can be measured in real time by switching the branch switches.

[0108] The embodiments disclosed herein can be applied to rapid process testing in packaging and bonding processes, including interconnect solder joints and interconnect metal lines, reflecting the stability of the bonding process by analyzing and measuring impedance. They can also be applied to reliability testing of critical components within interconnect structures, obtaining the failure time of the interconnect structure by real-time impedance monitoring, thereby predicting the characteristic lifetime of the component or the entire system. Particularly for electromigration reliability testing, the solutions disclosed herein have been applied to the lifetime assessment of packaged solder joints in CPU projects. Furthermore, they can be applied to impedance measurement equipment for precise measurement of minute impedances.

[0109] It will be understood by those skilled in the art that all or some of the steps in the methods disclosed above, and the functional modules / units in the apparatus, can be implemented as software, firmware, hardware, and suitable combinations thereof. In hardware implementations, the division between functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed collaboratively by several physical components. Some or all physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and can be accessed by a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0110] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. An interconnect structure impedance measurement circuit, characterized in that, include: The first branch, the second branch, and the third branch are connected in parallel. The first branch includes a first interconnect structure, a second interconnect structure, and a first switch connected in series. The second branch includes a first resistor, a second resistor, and a second switch connected in series. The third branch includes a third resistor, a fourth resistor, and a third switch connected in series. The impedance of the first interconnect structure and the impedance of the second interconnect structure are determined based on the first voltage between the first branch and the second branch, the second voltage between the first branch and the third branch, the first resistor, the second resistor, the third resistor, the fourth resistor, and the first current input to the impedance measurement circuit of the interconnect structure. Wherein, the first voltage is the voltage between the node between the first interconnect structure and the second interconnect structure and the node between the first resistor and the second resistor, and the first voltage is detected when the first switch and the second switch are closed and the third switch is open; The second voltage is the voltage between the node between the first interconnect structure and the second interconnect structure, and the node between the third resistor and the fourth resistor. The second voltage is detected when the first switch and the third switch are closed and the second switch is open.

2. The interconnection structure impedance measurement circuit as described in claim 1, characterized in that, The resistance value of the first resistor is not equal to the resistance value of the third resistor, and the resistance value of the second resistor is not equal to the resistance value of the fourth resistor.

3. The interconnection structure impedance measurement circuit as described in claim 1, characterized in that, The first interconnect structure and the second interconnect structure are connected to a printed circuit board (PCB). The interconnect structure impedance measurement circuit is disposed on the PCB, or the interconnect structure impedance measurement circuit is disposed on an interconnect structure impedance measurement device.

4. The interconnection structure impedance measurement circuit as described in any one of claims 1-3, characterized in that, The first interconnection structure is at least two fifth resistors connected in parallel, each fifth resistor having the same resistance value, and the resistance value of the fifth resistor is equal to the resistance value of the second interconnection structure; or, the first interconnection structure is a wire.

5. The interconnect structure impedance measurement circuit as described in claim 4, characterized in that, The first interconnection structure consists of n fifth resistors connected in parallel, where n is an integer greater than or equal to 2; the resistance of the second resistor is n times the resistance of the first resistor, and the resistance of the fourth resistor is n times the resistance of the third resistor.

6. An interconnect structure impedance measuring device, characterized in that, include: The constant current source, voltage detection module, control module, and interconnect structure impedance measurement circuit as described in any one of claims 1-5, wherein the constant current source is connected to the first branch, the second branch, and the third branch, and is used to provide a first current to the interconnect structure impedance measurement circuit when the first switch and the second switch are closed and the third switch is open, or when the first switch and the third switch are closed and the second switch is open; The voltage detection module is connected to the first branch, the second branch and the third branch respectively, and is used to detect the first voltage between the first branch and the second branch when the first switch and the second switch are closed and the third switch is open; In addition, when the first switch and the third switch are closed and the second switch is open, a second voltage between the first branch and the third branch is detected; The control module is used to control the constant current source to provide the first current to the interconnect structure impedance measurement circuit, and to control the first switch, the second switch and the third switch to open or close; and to acquire the first voltage and the second voltage detected by the voltage detection module, and to calculate the impedance of the first interconnect structure and the impedance of the second interconnect structure based on the first resistor, the second resistor, the third resistor, the fourth resistor, the first voltage, the second voltage and the first current.

7. The interconnect structure impedance measuring device as described in claim 6, characterized in that, The interconnect structure impedance measurement circuit is the interconnect structure impedance measurement circuit as described in claim 4 or 5; The constant current source is also used to provide a second current to the interconnect structure impedance measurement circuit when the first switch is closed and the second and third switches are open, wherein the second current is greater than the first current.

8. A method for measuring the impedance of an interconnect structure, characterized in that, The method, applied to the interconnect structure impedance measurement device as described in claim 6, comprises: Provide a first current to the impedance measurement circuit of the interconnect structure; The interconnection structure impedance measurement circuit is controlled to be in a first state to detect a first voltage between the first branch and the second branch; wherein, in the first state, the first switch and the second switch are closed and the third switch is open; The interconnection structure impedance measurement circuit is controlled to switch from the first state to the second state to detect the second voltage between the first branch and the third branch; wherein, in the second state, the first switch and the third switch are closed and the second switch is open; Stop supplying a first current to the impedance measurement circuit of the interconnect structure, and calculate the impedance of the first interconnect structure and the second interconnect structure based on the first resistor, the second resistor, the third resistor, the fourth resistor, the first voltage, the second voltage, and the first current.

9. A method for measuring the impedance of an interconnect structure, characterized in that, Applied to the interconnect structure impedance measurement device as described in claim 7, the method includes: The impedance of the second interconnect structure is measured using the method described in claim 8; The interconnect structure impedance measurement circuit is controlled to switch from the second state to the third state, in which the first switch is closed and the second switch and the third switch are open; A second current is provided to the impedance measurement circuit of the interconnect structure within a preset time period to increase the current stress and accelerate the degradation of the second interconnect structure; The impedance of the second interconnect structure is measured using the method described in claim 8, and compared with a preset failure impedance value until the impedance of the second interconnect structure reaches the failure impedance value, at which point the measurement ends.

10. The method as described in claim 9, characterized in that, The method further includes: Record the failure time from the start of providing the second current to the end of the measurement; The reliability of the second interconnect structure is analyzed based on the failure time.

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