A method for the combined analysis of components of an acidic copper plating solution for integrated circuit substrates

Abstract

The application belongs to the technical field of electrochemical analysis, and particularly relates to a combined analysis method for components of an integrated circuit carrier plate acidic copper plating solution, wherein the method comprises the following steps: S1, sequentially adding different concentrations of Cu 2+ , an accelerator, an inhibitor and a leveler into a test bottle to perform a CVS test and obtain electrochemical activity data; S2, constructing a kinetic model containing an accelerator influence factor F acc , an inhibitor influence factor F supp and a leveler influence factor F lev based on the data in S1, and fitting model parameters through a nonlinear regression algorithm; and S3, taking a to-be-tested solution to perform a CVS test, and inversely deducing concentrations of various additives in the to-be-tested solution according to the kinetic model in S2.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical analysis technology, and more specifically, relates to a combined analysis method for the components of acidic copper plating solution on integrated circuit substrates. Background Technology

[0002] Acidic copper plating solutions are widely used in semiconductor packaging substrates and integrated circuit manufacturing. The concentration of its organic additives directly affects the uniformity of the plating layer, the quality of blind via filling, and the product yield.

[0003] Acidic copper plating solutions mainly consist of VMS (Vacuum-Modified Sulfate), accelerators, inhibitors, and leveling agents. VMS serves as the base plating solution, while the accelerators, inhibitors, and leveling agents are collectively referred to as additives. Acidic copper plating solutions are a key factor influencing the quality of copper plating on encapsulation substrates, and timely monitoring and adjustment of their concentrations are crucial in industrial manufacturing. CVS (Continuous Voltage Suppressor) is a commonly used electrochemical analysis method for organic additives in copper plating. Currently, in practical industrial applications, to monitor the concentrations of accelerators, inhibitors, and leveling agents in organic encapsulation substrates, multiple daily samplings and CVS analysis of the three organic additives are required. Furthermore, the three additives cannot be tested simultaneously and must be analyzed individually. Completing the analysis of all three additives takes 4-6 hours or more per session, which is time-consuming, labor-intensive, and involves high costs for CVS electrode consumables.

[0004] Therefore, in view of this, we have studied and improved the existing structure and its shortcomings, and provided a joint analysis method for the components of acidic copper plating solution on integrated circuit substrates, in order to achieve a more practical purpose. Summary of the Invention

[0005] In view of the problems mentioned in the background art above, the present invention provides a joint analysis method for the components of acidic copper plating solution for integrated circuit substrates.

[0006] On the one hand: The technical solution adopted in this invention is as follows: A joint analysis method for the components of acidic copper plating solution for integrated circuit substrates, S1: Different concentrations of Cu are added sequentially to the test bottle. 2+ S1: Accelerators, inhibitors, and leveling agents were subjected to CVS tests to obtain electrochemical activity data; S2: Based on the data from S1, a model including the accelerator influence factor F was constructed. acc Inhibitor impact factor F supp Leveling agent influence factor F lev The kinetic model is obtained, and the model parameters are fitted by a nonlinear regression algorithm; S3: Take the test solution for CVS test, and infer the concentration of each additive in the test solution based on the kinetic model in S2.

[0007] Furthermore, the scan rate of the CVS test in S1 is 1~25 mV / s, and the potential range is -0.225 V to 1.575 V.

[0008] Furthermore, the dynamic model in S2 is as follows: .

[0009] Furthermore, the nonlinear regression algorithm in S2 is the Levenberg-Marquardt algorithm.

[0010] Furthermore, in step S3, the test solution is diluted stepwise and components are added to obtain multiple CVS curves, and all curve data are input into the kinetic model to jointly deduce the initial concentration of the test solution.

[0011] Secondly, the technical solution adopted by this invention is as follows: A combined analysis device for components of acidic copper plating solution on integrated circuit substrates, comprising a central processing system, an automatic feeding system, a temperature control and stirring system, and an electrochemical testing system. The central processing system is used to control the operation of the entire device and data analysis; the automatic feeding system is used to connect to the plating solution component bottle group for quantitatively aspirating and adding reagents to the test bottle; the temperature control and stirring system is used to maintain a constant temperature inside the test bottle and provide stirring; the electrochemical testing system includes a three-electrode system for performing cyclic voltammetry scans; wherein, the central processing system is electrically connected to the automatic feeding system, the temperature control and stirring system, and the electrochemical testing system.

[0012] Furthermore, the three-electrode system includes a working electrode, a counter electrode, and a reference electrode, wherein the working electrode is a Pt-Au electrode and the reference electrode is an AgCl electrode.

[0013] Furthermore, the temperature control and stirring system includes a magnetic stir bar and a temperature control module, with a temperature control accuracy of ±0.1℃ and a stirring rate range of 500–3000 RPM.

[0014] Third aspect: The technical solution adopted by the present invention is as follows: a copper electroplating solution production system, including the aforementioned device, for online monitoring and adjustment of the additive concentration in the electroplating solution.

[0015] The beneficial effects of this invention are:

[0016] 1. The central processing system integrates and controls feeding, temperature control, stirring, and testing, avoiding tedious manual operations and improving analytical efficiency and repeatability. Based on the established kinetic model, the concentration of multiple additives can be predicted simultaneously with only one test sequence, effectively shortening the analysis time from the large amount of time required by traditional methods. Moreover, the kinetic model fully considers the synergistic and competitive effects between additives, which are highly consistent with experimental data, and the relative error in predicting the concentration of unknown samples is small.

[0017] 2. The overall device has a compact structure and is easy to operate. It can be integrated into the electroplating production line to realize online real-time monitoring and intelligent control of additive concentration, which is of great significance for ensuring product quality and reducing production costs. Attached Figure Description

[0018] The present invention can be further illustrated by the non-limiting embodiments given in the accompanying drawings;

[0019] Figure 1 This is a schematic diagram of the device for automatically analyzing the concentration of additives in copper electroplating solution according to the present invention;

[0020] Figure 2 These are verification graphs of the experimental data and fitting data from Embodiments 1 to 4 of the present invention;

[0021] Figure 3 This is a schematic diagram comparing the experimental data and model fitting results of the random concentration solution in Example 5 of the present invention;

[0022] Figure 4 This is the j0-j5 regression curve of Embodiment Six of the present invention;

[0023] The attached diagram is labeled as follows:

[0024] Central processing system 1, automatic feeding system 2, electrochemical testing system 3, temperature control and stirring system 4, counter electrode 5, working electrode 6, magnetic stir bar 7, reference electrode 8, plating solution component bottle group 9. Detailed Implementation

[0025] like Figure 1 As shown, a combined analytical device for the components of acidic copper plating solution on an integrated circuit substrate includes a central processing system 1, an automatic feeding system 2, an electrochemical testing system 3, and a temperature control and stirring system 4. The automatic feeding system 2 can quantitatively extract reagents from the plating solution component bottle and add them to the test bottle. The temperature control and stirring system 4 maintains the test bottle at a specific temperature for stirring. The electrochemical testing system 3 performs cyclic voltammetry (CVS) using a three-electrode setup. The feed rate, testing temperature, and electrochemical testing are all controlled by the central processing system 1, which is also responsible for data acquisition and result analysis.

[0026] First, the central processing system 1 controls the automatic feeding system 2 to quantitatively draw reagents from the plating solution component bottle group 9, prepare a series of VMS solutions and additives, add them to the test bottle, stir evenly, and then start the CVS test to obtain electrochemical activity data under different compositions:

[0027] Specifically,

[0028] Example 1:

[0029] Collect different Cu 2+Electrochemical data: Preparation of 70 g / L H2SO4, 70 mg / L Cl - The solution, to which different Cu values ​​are added sequentially. 2+ To determine the concentration, the prepared solution was placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and a negative scan was performed to test the electrochemical curve.

[0030] Example 2: Collection of electrochemical data for different accelerators: Preparation of VMS solution (65 g / L Cu) 2+ 70g / L H2SO4, 70 mg / L Cl - Different concentrations of accelerator were added sequentially, and the prepared solution was placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and the negative scan was performed to test the electrochemical curve.

[0031] Example 3: Collection of electrochemical data for different inhibitors

[0032] Electrochemical data of inhibitors at high accelerator concentrations: Preparation of VMS solution (65 g / L Cu) 2+ 70 g / L H2SO4, 70 mg / L Cl - (3 mL / L accelerator), different concentrations of inhibitor were added to the solution, and the prepared solution was placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and the negative scan was performed to test the electrochemical curve.

[0033] Electrochemical data of inhibitors at low accelerator concentrations: Preparation of VMS solution (65 g / L Cu) 2+ 70 g / L H2SO4, 70 mg / L Cl - (0.1 mL / L accelerator), different concentrations of inhibitor were added to the solution, and the prepared solution was placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and the negative scan was performed to test the electrochemical curve.

[0034] Example 4: Collection of electrochemical data for different leveling agents

[0035] Electrochemical data of leveling agents under high accelerator and high inhibitor conditions: Preparation of VMS solution (65 g / L Cu) 2+ 70g / L H2SO4, 70 mg / L Cl - Different concentrations of leveling agent were added to the prepared solution (3 mL / L accelerator, 8 mL / L inhibitor). The prepared solution was then placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and the negative scan was performed to test the electrochemical curve.

[0036] Electrochemical data of leveling agents under low accelerator and high inhibitor conditions: Preparation of VMS solution (65 g / L Cu) 2+ 70g / L H2SO4, 70 mg / L Cl - (0.1 mL / L accelerator, 8 mL / L inhibitor) Different concentrations of leveling agent were added to the prepared solution, and the prepared solution was placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and the negative scan was performed to test the electrochemical curve.

[0037] Electrochemical data of leveling agent under low accelerator and low inhibitor conditions: Preparation of VMS solution (65 g / L Cu) 2+ 70g / L H2SO4, 70 mg / L Cl - (0.1 mL / L accelerator, 0.05 mL / L inhibitor) Different concentrations of leveling agent were added to the prepared solution, and the prepared solution was placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and the negative scan was performed to test the electrochemical curve.

[0038] Considering the synergistic effect of accelerators, inhibitors, and leveling agents on the reaction rate r, a kinetic model is constructed, as shown in Equation 1, introducing an accelerator influence factor F. acc See Equation 2, Inhibitor Impact Factor F supp See Equation 3 and the leveling agent influence factor F. levAs shown in Equation 4, the model parameters are fitted from the data collected in step 1 to form a dynamic model. The dynamic parameters are determined by nonlinear regression analysis using the Levenberg-Marquardt algorithm implemented in the SciPy.optimize package of Python.

[0039] (1)

[0040] (2)

[0041] (3)

[0042] (4)

[0043] (5)

[0044] (6)

[0045]

[0046]

[0047] Where c acc c supp c lev The concentrations of accelerator, inhibitor, and leveling agent are respectively, c Cu The concentration of copper ions is represented by . r represents the reaction rate, which in this formula can be equated to the current density, since for this additive-affected copper deposition reaction, the current density is a linear and precise measure of the reaction rate. E is the potential or overpotential; based on mathematical equivalence, both can be substituted into the calculation.

[0048] The rest are fitting parameters, among which,

[0049] F acc F represents the effect factor of the accelerator. supp F represents the influence factor of inhibitors. lev This indicates the influencing factor of the leveling agent.

[0050] k i and K i Let i represent the reaction rate constant and adsorption constant related to component i, respectively (i = Cu). 2+ , acc, acc2, acc3, supp, lev),

[0051] k0, i K represents the pre-exponential factor of the reaction rate constant associated with component i. 0,i This represents the pre-exponential factor of the adsorption constant related to component i. The potential coefficient represents the reaction rate constant associated with component i. The potential coefficient representing the adsorption constant associated with component i, i = Cu 2+ , acc, acc2, acc3, supp, lev,

[0052] a represents Cu 2+ The slope of the reaction order versus potential, where b represents Cu 2+ The intercept of the reaction order versus potential.

[0053] a lev b represents the slope of the relationship between the concentration exponent and potential of the leveling agent in the rate expression. lev The intercept represents the relationship between the leveling agent concentration index and the potential.

[0054] n j Let j represent the concentration exponent of component j in the rate expression, where j = acc, acc2, acc3, supp.

[0055] The above formula has the following characteristics: (1) When the concentration of any additive is 0, its influence factor is 1; (2) After copper ions and any additive reach a certain concentration, their influence factor tends to a constant, corresponding to the concentration saturation phenomenon in the experiment; (3) Introducing F acc2 The synergistic effect of accelerators and inhibitors is that the accelerator has a more significant acceleration effect in the presence of inhibitors; (4) Introducing F acc3 The synergistic effect of the accelerator and the leveling agent is that the leveling agent exhibits an accelerating effect under low accelerator conditions and an inhibiting effect under high accelerator conditions; (5) The exponential terms of copper ion and additive concentration are both related to potential, corresponding to the non-specific adsorption characteristics of charged particles on the electrode.

[0056] The data collected in Examples 1 to 4 were fitted with model parameters according to Equation 1 to form a dynamic model. The Levenberg-Marquardt algorithm implemented in the SciPy.optimize package of Python was used to determine the dynamic parameters through nonlinear regression analysis. The initial parameter values ​​were all 0.1. The convergence criteria were xtol=1e-8, ftol=1e-8, gtol=1e-8. The data fitting parameters are shown in Table 1 below.

[0057] Table 1: Parameters for fitting experimental data

[0058]

[0059] After building the dynamic model, the experimental test data and the model fitting data were compared. Figure 2 The experimental data and the model fit data showed good matching.

[0060] Secondly, after establishing the kinetic model, the random concentration is validated.

[0061] Specifically as follows:

[0062] Example 5: In 70 g / L H2SO4, 70 mg / L Cl - Different concentrations of Cu were added to the solution. 2+ Accelerators, inhibitors, and leveling agents were added. The prepared solutions of random concentrations were placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and the negative scan was performed to test the electrochemical curve.

[0063] like Figure 3 As shown, the experimental data of the randomly measured solutions are compared with the model fitting results. The actual measured data and the fitted data at different random concentrations show good matching.

[0064] Finally, the composition of the unknown solution concentration is determined to realize the overall scheme. The composition of the unknown solution concentration is determined by the kinetic model, without spending a lot of time on sequential determination.

[0065] Example 6: An unknown solution was placed in a three-electrode system with AgCl as the reference electrode and Pt-Au as the working electrode. The stirring rate was 2500 RPM, the initial volume was 50 mL, the scan rate was 25 mV / s, the positive limit was 1.575 V, the negative limit was -0.225 V, and the negative scan was performed. The electrochemical curves were tested according to the steps described in Table 2 below and denoted as j0-j5.

[0066] Table 2: Composition determination of unknown solution concentration

[0067]

[0068] Based on the experimental values ​​of j0-j5, the above dynamic model is used to regress c. Cu c Acc c Supp c Lev The value, the regression curve is as follows Figure 4 As shown in Table 3 below, the regression results are as follows.

[0069] Table 3: Regression Results of j0-j5 in Example 6

[0070]

[0071] The present invention has been described in detail above. The specific embodiments are provided only to help understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for joint analysis of components in acidic copper plating solution for integrated circuit substrates, characterized in that: S1: Add different concentrations of Cu to the test bottle sequentially. 2+ Accelerators, inhibitors, and leveling agents were subjected to CVS tests to obtain electrochemical activity data; S2: Based on the data in S1, construct a dynamic model and fit the model parameters of the dynamic model using a nonlinear regression algorithm, wherein the dynamic model is: In the formula, r represents the reaction rate, E represents the potential or overpotential, and c Cu c represents the concentration of copper ions. acc c supp c lev These represent the concentrations of the accelerator, inhibitor, and leveling agent, respectively. F acc F supp F lev F represents the accelerator impact factor, inhibitor impact factor, and leveling agent impact factor, respectively. acc2 F represents the interaction factor between accelerators and inhibitors. acc3 This indicates the interaction factor between the accelerator and the leveling agent; k i and K i Let represent the reaction rate constant and adsorption constant related to component i, respectively. , , i=Cu, acc, acc2, acc3, supp, lev, k 0,i and K 0,i Let α represent the pre-exponential factor of the reaction rate constant and the pre-exponential factor of the adsorption constant, respectively, related to component i. i and β i ... 2+ The slope and intercept of the relationship between reaction order and potential; a lev and b lev Let n represent the slope and intercept of the concentration exponent versus potential relationship of the leveling agent in the rate expression, respectively; j The concentration exponent of component j in the rate expression is represented by j = acc, acc2, acc3, supp; S3: Perform CVS testing on the test solution. The test solution is diluted and components are added stepwise to create multiple different compositional conditions, resulting in multiple CVS curves. All data from these multiple CVS curves are input into the kinetic model described in S2 to jointly infer the Cu content in the test solution. 2+ The initial concentrations of accelerators, inhibitors, and leveling agents.

2. The method for joint analysis of components in acidic copper plating solution for integrated circuit substrates according to claim 1, characterized in that: The scan rate of the CVS test in S1 is 1~25 mV / s, and the potential range is -0.225 V to 1.575 V.

3. The method for joint analysis of components in acidic copper plating solution for integrated circuit substrates according to claim 1, characterized in that: The nonlinear regression algorithm in S2 is the Levenberg-Marquardt algorithm.

4. A combined analytical apparatus for analyzing the components of acidic copper plating solution on integrated circuit substrates, used to perform the method according to any one of claims 1-3, characterized in that: include: A central processing system, which is used to control the operation of the entire device and perform data analysis; An automatic feeding system is used to connect to the plating solution component bottle group for quantitatively drawing and adding reagents to the test bottle; Temperature control and stirring system, used to maintain a constant temperature inside the test bottle and provide stirring; An electrochemical testing system, including a three-electrode system, is used for cyclic voltammetry scanning; The central processing system is electrically connected to the automatic feeding system, the temperature control and stirring system, and the electrochemical testing system.

5. The combined analysis apparatus for the components of acidic copper plating solution on an integrated circuit substrate according to claim 4, characterized in that: The three-electrode system includes a working electrode, a counter electrode, and a reference electrode. The working electrode is a Pt-Au electrode, and the reference electrode is an AgCl electrode.

6. The combined analysis apparatus for the components of acidic copper plating solution on integrated circuit substrates according to claim 5, characterized in that: The temperature control and stirring system includes a magnetic stir bar and a temperature control module, with a temperature control accuracy of ±0.1℃ and a stirring rate range of 500–3000 RPM.

7. A copper electroplating solution production system, characterized in that, A combined analysis device including the components of the acidic copper plating solution for integrated circuit substrates as described in any one of claims 4 to 6, for online monitoring and adjustment of the additive concentration in the plating solution.

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