Micro-copper pillar bump interconnection resistor electromigration degradation prediction method

Abstract

The invention discloses a micro-copper pillar bump interconnection resistor electromigration degradation prediction method. The method comprises the following steps: obtaining the net flux of Cu atoms in a Cu6Sn5 layer and a Cu3Sn layer and the net flux of Ni atoms in a Ni-Cu-Sn compound layer under forward current and reverse current; establishing a relationship between the net flux of Ni atoms and the thickness change of the Ni-Cu-Sn compound layer and a relationship between the net flux of Cu atoms and the thickness change of the Cu6Sn5 layer and the Cu3Sn layer; establishing a thickness polarity growth model of the Ni-Cu-Sn compound, the Cu6Sn5 layer and the Cu3Sn layer; establishing a thickness polarity consumption model of the Cu bonding pad, the Sn solder and the Ni layer; and establishing a resistance electromigration degradation model of micro-copper pillar bump interconnection. According to the method, the electromigration degradation prediction of the interconnection resistor of the copper pillar bump plated with the Ni layer can be realized, and a large amount of service life and time and economic cost generated by a failure analysis test are greatly reduced or avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuit packaging, and in particular relates to a method for predicting electromigration degradation of interconnection resistance of micro copper pillar bumps. Background Art

[0002] During the micro-copper pillar bump manufacturing process, a Ni barrier layer is typically electroplated between the Cu pillar and the Sn solder to prevent direct contact between the Cu and Sn solder, thereby slowing down the Cu-Sn reaction. However, the introduction of the Ni layer results in the formation of a Ni-Cu-Sn compound layer within the interconnect. Differences in interconnect structure and composition alter the growth patterns of the interfacial metal compound layer within the bump interconnect. Furthermore, coupled current stress loading and differences in current direction induce polarized growth of the Ni layer, the Ni-Cu-Sn compound layer, and the Cu-Sn compound layer, thus altering the electromigration degradation of the interconnect resistance.

[0003] The existing technology is based on the numerical analysis of the migration flux of single metal atoms (Cu atoms or Sn atoms). By obtaining the net flux of Cu atoms in the Cu6Sn5 layer and the Cu3Sn layer, it is converted into a growth model of the Cu6Sn5 and Cu3Sn layers with electromigration stress time. However, it cannot be used to evaluate the effect of introducing a Ni layer structure in the bump interconnect on the growth of interfacial metal compounds and analyze the growth of the Ni-Cu-Sn compound layer. It also cannot be used to predict the electromigration degradation of the bump interconnect resistance. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for predicting the electromigration degradation of the interconnect resistance of micro copper pillar bumps, a computer device, a computer-readable storage medium, and a computer program product, which can provide an effective solution for predicting the electromigration degradation of the interconnect resistance of copper pillar bumps with Ni plating, greatly reducing or avoiding the time and economic costs generated by a large number of life and failure analysis tests.

[0005] One aspect of the present invention provides a method for predicting electromigration degradation of resistance of a micro-copper pillar bump interconnect. The micro-copper pillar bump interconnect comprises, from top to bottom, a copper pillar, a Ni layer, a Ni-Cu-Sn compound layer, a Sn solder, a Cu6Sn5 layer, a Cu3Sn layer, and a Cu pad. The method comprises:

[0006] The direction from the Cu pad to the Sn solder is selected as the forward current direction, and the opposite direction of the forward current is selected as the reverse current direction. The net flux of Cu atoms in the Cu6Sn5 layer and Cu3Sn layer under forward current and reverse current are obtained, respectively, as well as the net flux of Ni atoms in the Ni-Cu-Sn compound layer.

[0007] Based on the obtained Cu atomic net flux and Ni atomic net flux, the relationship between the Ni atomic net flux and the change of Ni-Cu-Sn compound layer thickness under forward current and reverse current as well as the relationship between the Cu atomic net flux and Cu6Sn s The relationship between the thickness change of the layer and the Cu3Sn layer;

[0008] According to the relationship between the net flux of Ni atoms and the thickness change of Ni-Cu-Sn compound layer and the net flux of Cu atoms and Cu6Sn s The relationship between the thickness change of the Ni-Cu-Sn compound layer and the Cu3Sn layer under forward current and reverse current is established. s Thickness polar growth model of Cu3Sn layer and Cu3Sn layer;

[0009] Based on Ni-Cu-Sn compound layer, Cu6Sn s The thickness polarity growth model of the Ni layer and Cu3Sn layer is established, and the thickness polarity consumption model of the Ni layer, Sn solder and Cu pad is established under forward current and reverse current;

[0010] Based on the thickness polar growth model of Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer and the thickness polar consumption model of Ni layer, Sn solder and Cu pad, the resistance electromigration degradation model of micro copper pillar bump interconnection under forward current and reverse current is established.

[0011] Another aspect of the present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above method.

[0012] Another aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the above method when executed by a processor.

[0013] Yet another aspect of the present invention provides a computer program product, comprising a computer program, which implements the steps of the above method when executed by a processor.

[0014] The method, computer device, computer-readable storage medium, and computer program product for predicting electromigration degradation of the interconnect resistance of micro-copper pillar bumps according to the above aspects of the present invention can provide an effective solution for predicting electromigration degradation of the interconnect resistance of Ni-plated copper pillar bumps, thereby greatly reducing or avoiding the time and economic costs incurred by a large number of life and failure analysis tests. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts.

[0016] Figure 1 This is a flow chart of a method for predicting electromigration degradation of micro-copper pillar bump interconnect resistance according to one embodiment of the present invention;

[0017] Figure 2 Schematic diagram of Cu and Ni atomic fluxes under forward current in a micro copper pillar bump interconnect according to one embodiment of the present invention;

[0018] Figure 3 Schematic diagram of Cu and Ni atomic fluxes under reverse current in a micro copper pillar bump interconnect according to one embodiment of the present invention;

[0019] Figure 4 It is a structural diagram of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0021] One embodiment of the present invention provides a method for predicting the electromigration degradation of the resistance of micro-copper pillar bump interconnects. The method establishes a prediction model for the electromigration degradation of the resistance of micro-copper pillar bump interconnects based on the thermal diffusion and electromigration flux analysis of two target metal atoms (Cu and Ni). The micro-copper pillar bump interconnects include, from top to bottom, a Ni layer, a Ni-Cu-Sn compound layer, Sn solder, a Cu6Sn5 layer, a Cu3Sn layer, and a Cu pad. The Ni-Cu-Sn compound layer is mainly composed of (Ni x Cu 1-x )6Sn5 compound, where x represents the proportion of Ni atoms. Figure 1 FIG. 1 is a flow chart of a method for predicting electromigration degradation of micro-copper pillar bump interconnect resistance according to an embodiment of the present invention. Figure 1 As shown, the method of the embodiment of the present invention includes steps S1 to S5.

[0022] Step S1: Analysis of bimetallic atomic flux under forward and reverse currents

[0023] First, based on the analysis of the target bimetallic atomic migration patterns under forward current, the thermal diffusion and electromigration fluxes of Cu atoms in the Cu6Sn5 and Cu3Sn layers, and the thermal diffusion and electromigration fluxes of Ni atoms in the Ni-Cu-Sn compound layer, were obtained. The direction from the Cu pad to the Sn solder was selected as the forward current direction (the electron flow direction is opposite to the current direction, from the Sn solder to the Cu pad).

[0024] Figure 2 This is a schematic diagram of the Cu and Ni atomic fluxes under forward current in a micro copper pillar bump interconnection according to an embodiment of the present invention. Figure 2 middle, and It represents the thermal diffusion flux of Cu atoms caused by the concentration gradient, and the directions are from the Cu pad to the Cu3Sn layer, from the Cu3Sn layer to the Cu6Sn layer, and from the Cu6Sn5 layer to the Sn solder. and They represent the Ni atomic thermal diffusion flux caused by the concentration gradient, and the directions are from the Ni layer to (Ni x Cu 1-x )6Sn5 layer (Ni-Cu-Sn compound layer), from (Ni x Cu 1-x )6Sn5 layer (Ni-Cu-Sn compound layer) to Sn solder. They represent the electron wind force between Sn solder and Cu6Sn5 layer, Cu6Sn s The electromigration flux of Cu atoms between the Sn solder layer and the Cu3Sn layer, and between the Cu3Sn layer and the Cu pad are from Sn solder to the Cu6Sn5 layer, from the Cu6Sn5 layer to the Cu3Sn layer, and from the Cu3Sn layer to the Cu pad, respectively. and They represent the Ni atomic electromigration flux between the Ni layer and the Ni-Cu-Sn compound layer and between the Ni-Cu-Sn compound layer and the Sn solder caused by the electron wind, and the directions are from the Ni layer to (Ni x Cu 1-x )6Sn5 layer (Ni-Cu-Sn compound layer), from (Ni x Cu 1-x )6Sn5 layer (Ni-Cu-Sn compound layer) to Sn solder.

[0025] Next, the reverse current direction is chosen as the direction opposite to the forward current. Based on the analysis of the target bimetallic atomic migration patterns under reverse current, the thermal diffusion and electromigration fluxes of Cu atoms in the Cu6Sn5 and Cu3Sn layers, and the thermal diffusion and electromigration fluxes of Ni atoms in the Ni layer and Ni-Cu-Sn compound layer, are obtained. Here, the reverse current direction is from the Sn solder to the Cu pad (the electron flow direction is opposite to the current direction, flowing from the Cu pad to the Sn solder).

[0026] Figure 3 Schematic diagram of Cu and Ni atomic flux under reverse current in a micro copper pillar bump interconnection according to an embodiment of the present invention. Figure 3 It can be seen that the direction of the thermal diffusion flux of Cu and Ni atoms driven by the concentration gradient has not changed, but the direction of the electromigration flux of Cu and Ni atoms driven by the electron wind has changed. It represents the electromigration flux of Cu atoms in the Cu pad driven by electron wind, and the direction is from the Cu pad to the Cu3Sn layer. Because the Cu single substance structure has good anti-electromigration performance, It can be ignored in the calculation process.

[0027] Step S2: Analysis of the net flux of bimetallic atoms under forward current and reverse current

[0028] First, the net flux of Ni atoms in the Ni-Cu-Sn compound layer and the net flux of Cu atoms in the Cu6Sn5 layer and Cu3Sn layer under forward current were obtained. Based on the obtained net flux of Cu and Ni atoms, the relationship between the net flux of Cu and Ni bimetallic atoms and the thickness growth of metal compounds at different interfaces (the relationship between thickness changes) was established. The main analysis is as follows:

[0029] When the current is forward, for the Ni-Cu-Sn compound layer at the cathode, we can obtain:

[0030]

[0031] in:

[0032]

[0033] Where C Ni 、D Ni and are the atomic concentration, thermal diffusivity and effective charge number of Ni in the Ni layer, ρ Ni is the resistivity of the Ni layer, e is the unit charge, j is the average current density, k is the Boltzmann constant, T is the Kelvin temperature, C Ni / mix 、D Ni / mix and They are the atomic concentration, thermal diffusivity and effective charge number of Ni in the Ni-Cu-Sn compound layer, mix正 and Δmix 正 are the thickness and thickness change of Ni-Cu-Sn compound layer under forward current, t is time, C Ni / Sn is the concentration of Ni atoms dissolved in Sn solder, ρ mix is the resistivity of the Ni-Cu-Sn compound layer.

[0034] When the current is forward, for the Cu6Sn5 layer and Cu3Sn layer of the anode, we can get:

[0035]

[0036] in:

[0037]

[0038] Where η 正 and ε 正 , Δη 正 and Δε 正 are the thickness and thickness change of Cu6Sn5 layer and Cu3Sn layer under forward current, D Cu / η 、D Cu / ε and D Cu / Sn are the thermal diffusivities of Cu atoms in the Cu6Sn5 layer, Cu3Sn layer and Sn solder, respectively, and C Cu 、C Cu / η 、C Cu / ε and C Cu / Sn are the atomic concentrations of Cu in the Cu pad, Cu6Sn5 layer, Cu3Sn layer and Sn solder, respectively. and are the effective charge numbers of Cu in the Cu6Sn5 layer, Cu3Sn layer and Sn solder, ρ η , ρ ε and ρ Sn They are the resistivities of Cu6Sn5 layer, Cu3Sn layer and Sn solder, respectively.

[0039] For the Ni-Cu-Sn compound layer of the cathode, combining formulas (1) and (2) we can obtain:

[0040]

[0041] in:

[0042]

[0043] For the Cu6Sn5 layer and Cu3Sn layer of the anode, combining formulas (3), (4) and (5) we can obtain:

[0044]

[0045] in:

[0046]

[0047] Secondly, the net flux of Ni atoms in the Ni-Cu-Sn compound layer, the net flux of Cu atoms in the Cu6Sn5 layer, and the Cu3Sn layer under reverse current were obtained. Based on the obtained net flux of Cu and Ni atoms, the relationship between the net flux of Cu and Ni bimetallic atoms and the thickness growth of metal compounds at different interfaces (the relationship between thickness changes) was established. The main analysis is as follows:

[0048] When the current is reversed, for the Ni-Cu-Sn compound layer at the anode, we can obtain:

[0049]

[0050] When the current is reversed, the Cu6Sn5 layer of the cathode and the Cu 3 Sn layer, we can get:

[0051]

[0052]

[0053] in:

[0054]

[0055] Among them, mix 反 and Δmix 反 ,η 反 and Δη 反 , ε 反 and Δε 反 They are Ni-Cu-Sn compound layer under reverse current, Cu6Sn s The thickness of the Cu3Sn layer and the thickness change values.

[0056] For the Ni-Cu-Sn compound layer of the anode, combining formulas (2) and (11) we can obtain:

[0057]

[0058] in:

[0059]

[0060] For the cathode Cu6Sn s layer and Cu3Sn layer, combining formulas (12), (13) and (10) we can get:

[0061]

[0062] in:

[0063]

[0064] Step S3: Construction of thickness polar growth model of Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer

[0065] In this step, based on the relationship between the net flux of Cu and Ni bimetallic atoms and the thickness of different interface metal compounds under forward and reverse current, the growth relationship between the thickness of Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer and thermoelectric stress time under forward and reverse current is established (thickness polarity growth model). The main analysis is as follows:

[0066] When the current is forward, integrating and solving equations (6), (8) and (9) respectively yields:

[0067]

[0068] When the current is reversed, integrating and solving equations (15), (17) and (18) respectively yields:

[0069]

[0070] where C1, C2, and C3 are integral calculation constants related to the thickness of the initial Ni-Cu-Sn compound layer, the Cu6Sn5 layer, and the Cu3Sn layer, respectively.

[0071] Step S4: Construction of thickness polarity consumption model of Ni layer, Sn solder, and Cu pad

[0072] In this step, according to the conversion relationship of density, molar mass and atomic ratio in different metal layers and interface metal compound layers, the Ni-Cu-Sn layer, Cu6Sn layer and Cu6Sn layer can be used as the raw materials. s The thickness polarity growth model of the Ni layer and Cu3Sn layer is established, and the thickness polarity consumption model of the Ni layer, Sn solder, and Cu pad is established, as shown below:

[0073] Under forward current:

[0074]

[0075] Under reverse current:

[0076]

[0077] Among them, L Ni-正 、L Ni-反 , L Sn-正 、L Sn-反 , Lpad-正 、L pad-反 are the thicknesses of the Ni layer, Sn solder, and Cu pad in the bump structure under forward and reverse current, respectively. Ni0, Sn0, and pad0 are the initial thicknesses of the Ni layer, Sn solder, and Cu pad, respectively. mix0, η0, and ε0 are the initial thicknesses of the Ni-Cu-Sn compound layer, Cu6Sn5 layer, and Cu3Sn layer, respectively.

[0078] Step S5: Construction of electromigration degradation model of micro copper pillar bump interconnect resistance

[0079] In this step, according to the conversion relationship between the density, molar mass and atomic ratio in different metal layers and the interface metal compound layer, the resistance electromigration degradation model of the micro copper pillar bump interconnect can be established based on the thickness polarity growth model of the Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer and the thickness electromigration consumption model of the Cu pad, Sn solder and Ni layer, as shown below:

[0080]

[0081] Among them, R 正 is the resistance of the micro-copper pillar bump interconnect under forward current, R 反 is the resistance of the micro-copper pillar bump interconnection under reverse current, S is the cross-sectional area of ​​the micro-copper pillar bump interconnection; ρ Cu is the resistivity of copper (copper pillars and copper pads); L pillar is the thickness of the copper pillar, which is constant and does not change with electromigration time.

[0082] The following is a detailed description of the method for predicting electromigration degradation of the interconnect resistance of micro copper pillar bumps according to an embodiment of the present invention through examples.

[0083] For example, in the interconnection of micro copper pillar bumps in the package of a certain integrated circuit product, (Ni x Cu 1-x )6Sn5 layer has a ratio of x to 0.75, that is, the composition of the Ni-Cu-Sn compound is (Ni 0.75 Cu 0.25 )6Sn5, after all the soldering processes of the bump interconnection are completed, the initial copper column thickness (height) is 55um, the Ni layer thickness is 0.5um, (Ni 0.75 Cu 0.25 The thickness of the 6Sn5 layer is 0.2um, the thickness of the Sn solder is 5um, the thickness of the Cu6Sn5 layer is 2.5um, the thickness of the Cu3Sn layer is 1um, the thickness of the Cu pad is 10um, and the cross-sectional area of ​​the bump interconnect is 1962.5um. 2 .

[0084] It is required to predict: temperature 100℃ and current density 1.0×104 A / cm 2 Under the conditions of forward current and reverse current (Ni 0.75 Cu 0.25 )6Sn5 layer, Cu6Sn5 layer, and Cu3Sn layer thickness growth after 50h, 75h, and 100h, as well as the resistance change of micro-copper pillar bump interconnection under forward and reverse current.

[0085] By consulting relevant literature and data, the model parameters required for solving the model to calculate the electromigration degradation of the micro-copper pillar bump interconnect resistance are shown in Table 1 below:

[0086] Table 1 Model parameters required for model solution calculation

[0087]

[0088]

[0089] Substituting the relevant parameters in Table 1 into the thickness polarity growth model and thickness polarity consumption model of the interface metal compound (Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer), the following Tables 2 to 5 can be obtained:

[0090] Table 2 Growth of interfacial metal compounds under forward current

[0091]

[0092] Table 3 Consumption of metal layers (Cu pad, Sn solder, Ni layer) under forward current

[0093]

[0094] Table 4 Growth of interfacial metal compounds under reverse current

[0095]

[0096] Table 5 Metal layer consumption under reverse current

[0097]

[0098]

[0099] Substituting the relevant parameters into formula (24), we can obtain:

[0100] Table 6 Resistance changes

[0101]

[0102] According to an embodiment of the present invention, a method for predicting the electromigration degradation of resistance in micro-copper pillar bump interconnects is described. Two different target metal atoms (Cu and Ni) are selected from the composition. The thermal diffusion flux and electromigration flux of the two target metal atoms under different current directions are numerically analyzed to obtain the net flux of the corresponding target metal atoms in the interface metal compound layer. A thickness growth model of different interface metal compound layers in the interconnect structure under different current directions is established. The growth of the interface metal compound layer under thermal-electric coupling stress is predicted, thereby predicting the electromigration degradation of resistance in micro-copper pillar bump interconnects. The method of the embodiment of the present invention can effectively evaluate the electromigration degradation of resistance in micro-copper pillar bump interconnects without damaging the microelectronics, significantly reducing or avoiding the time and economic costs associated with extensive life and failure analysis testing. The method is not only universally applicable but also provides an effective solution for predicting the electromigration degradation of resistance in Ni-plated copper pillar bump interconnects in integrated circuit product packaging, such as chips, with significant economic and social benefits.

[0103] The embodiment of the present invention further provides a computer device, which may be a server, and its internal structure diagram may be as shown in FIG. Figure 4 As shown. The computer device includes a processor, a memory and a network interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store operating parameter data of each framework. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, the steps of the method of the embodiment of the present invention are implemented.

[0104] Those skilled in the art will understand that Figure 4 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0105] An embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the method of the embodiment of the present invention are implemented.

[0106] An embodiment of the present invention further provides a computer program product, including a computer program, which implements the steps of the method of the embodiment of the present invention when executed by a processor.

[0107] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A method for predicting electromigration degradation of resistance of a micro-copper pillar bump interconnect, wherein the micro-copper pillar bump interconnect comprises, from top to bottom, a copper pillar, a Ni layer, a Ni-Cu-Sn compound layer, a Sn solder, a Cu6Sn5 layer, a Cu3Sn layer, and a Cu pad, characterized in that: The method comprises: The direction from the Cu pad to the Sn solder is selected as the forward current direction, and the opposite direction of the forward current is selected as the reverse current direction. The net flux of Cu atoms in the Cu6Sn5 layer and Cu3Sn layer under forward current and reverse current are obtained, respectively, as well as the net flux of Ni atoms in the Ni-Cu-Sn compound layer. Based on the obtained Cu atomic net flux and Ni atomic net flux, the relationship between the Ni atomic net flux and the change of Ni-Cu-Sn compound layer thickness under forward current and reverse current as well as the relationship between the Cu atomic net flux and Cu6Sn s The relationship between the thickness change of the layer and the Cu3Sn layer; Based on the relationship between the net flux of Ni atoms and the thickness change of the Ni-Cu-Sn compound layer, as well as the relationship between the net flux of Cu atoms and the thickness change of the Cu6Sn5 layer and Cu3Sn layer, thickness polarity growth models of the Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer under forward and reverse current are established; Based on the thickness polarity growth model of Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer, the thickness polarity consumption model of Ni layer, Sn solder and Cu pad under forward current and reverse current was established. Based on the thickness polar growth model of Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer and the thickness polar consumption model of Ni layer, Sn solder and Cu pad, the resistance electromigration degradation model of micro copper pillar bump interconnection under forward current and reverse current is established.

2. The method according to claim 1, wherein The resistance electromigration degradation model of micro-copper pillar bump interconnection under forward current and reverse current is: Among them, R 正 is the resistance of the micro-copper pillar bump interconnect under forward current, R 反 is the resistance of the micro-copper pillar bump interconnection under reverse current, S is the cross-sectional area of ​​the micro-copper pillar bump interconnection, ρ Cu , ρ Ni , ρ mix , ρ Sn , ρ η , ρ ε The resistivity of copper, Ni layer, Ni-Cu-Sn compound layer, Sn solder, Cu6Sn5 layer, and Cu3Sn layer in the copper pillar and Cu pad, respectively, L pillar 、L Ni-正 、L Ni-反 、mix 正 、mix 反 、L Sn-正 、L Sn-反 ,η 正 ,η 反 , ε 正 , ε 反 、L pad-正 、L pad-反 They are the thickness of the copper pillar and the Ni layer, Ni-Cu-Sn compound layer, Sn solder, Cu6Sn5 layer, Cu3Sn layer, and Cu pad under forward current and reverse current.

3. The method according to claim 2, wherein The thickness polarity consumption model of Ni layer, Sn solder and Cu pad under forward current and reverse current is: Under forward current: Under reverse current: Among them, Ni0, Sn0, and pad0 are the initial thicknesses of the Ni layer, Sn solder, and Cu pad, respectively; mix0, η0, and ε0 are the initial thicknesses of the Ni-Cu-Sn compound layer, Cu6Sn5 layer, and Cu3Sn layer, respectively.

4. The method according to claim 3, wherein Ni-Cu-Sn compound layer, Cu6Sn under forward current and reverse current s The thickness polar growth model of the Cu3Sn layer and Cu3Sn layer is: Under forward current: Under reverse current: Where C1, C2 and C3 are integral calculation constants related to the thickness of the initial Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer, respectively, and t is time; Among them, C Ni 、D Ni and are the atomic concentration, thermal diffusivity and effective charge number of Ni in the Ni layer, C Ni / mix 、D Ni / mix and are the atomic concentration, thermal diffusivity and effective charge number of Ni in the Ni-Cu-Sn compound layer, C Ni / Sn is the concentration of Ni atoms dissolved in Sn solder, D Cu / η 、D Cu / ε and D Cu / Sn are the thermal diffusivities of Cu atoms in the Cu6Sn5 layer, Cu3Sn layer and Sn solder, respectively, and C Cu 、C Cu / η 、C Cu / ε and C Cu / Sn are the atomic concentrations of Cu in the Cu pad, Cu6Sn5 layer, Cu3Sn layer and Sn solder, respectively. and are the effective charge numbers of Cu in the Cu6Sn5 layer, Cu3Sn layer and Sn solder, respectively; e is the unit charge; j is the average current density; k is the Boltzmann constant; and T is the Kelvin temperature.

5. The method according to claim 4, wherein The relationship between the net flux of Ni and Cu atoms and the growth of interfacial metal compounds under forward and reverse currents is: The relationship between the net flux of Ni atoms and the change in the thickness of the Ni-Cu-Sn compound layer under forward current, as well as the relationship between the net flux of Cu atoms and the change in the thickness of the Cu6Sn5 layer and Cu3Sn layer are: Among them, Δmix 正 , Δη 正 and Δε 正 are the thickness changes of Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer under forward current, and, in, and denote the thermal diffusion flux of Ni atoms from the Ni layer to the Ni-Cu-Sn compound layer and from the Ni-Cu-Sn compound layer to the Sn solder, respectively. and are the Ni atomic electromigration fluxes between the Ni layer and the Ni-Cu-Sn compound layer and between the Ni-Cu-Sn compound layer and the Sn solder, respectively. and They represent the thermal diffusion flux of Cu atoms from the Cu pad to the Cu3Sn layer, from the Cu3Sn layer to the Cu6Sn5 layer, and from the Cu6Sn5 layer to the Sn solder, respectively. They represent the Cu atomic electromigration flux between Sn solder and Cu6Sn5 layer, between Cu6Sn5 layer and Cu3Sn layer, and between Cu3Sn layer and Cu pad, respectively.

6. The method according to claim 4 or 5, characterized in that The relationship between the net flux of Ni atoms and the thickness change of the Ni-Cu-Sn compound layer under reverse current, as well as the relationship between the net flux of Cu atoms and the thickness change of the Cu6Sn5 layer and Cu3Sn layer are as follows: Among them, Δmix 反 , Δη 反 and Δε 反 are the thickness changes of Ni-Cu-Sn compound layer, Cu6Sn5 layer and Cu3Sn layer under reverse current, and, 7. The method according to any one of claims 1 to 5, wherein Ni-Cu-Sn compound is (Ni x Cu 1-x )6Sn5, where x represents the proportion of Ni atoms.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory, wherein: The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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