Quantitative method of electrocoppering oxidation-reduction type additive

Abstract

The invention belongs to the field of electronic circuit manufacturing, relates to a damascene wafer copper electroplating technology, a packaging carrier plate and a copper electroplating technology related to a printed circuit board, and particularly provides a quantitative method of a copper electroplating redox type additive, which is used for realizing concentration measurement of the redox type additive in an acid sulfate electronic copper electroplating solution. The method for measuring the consumed charge quantity of the redox type additive is provided on the basis of a voltammetry analysis method, meanwhile, the Faraday current efficiency of the electroplating liquid can be measured, and the consumed charge quantity of the redox type additive or the Faraday current efficiency is calibrated; the method is combined with an electrochemical quantitative analysis method to measure the concentration of the redox type additive in the electroplating solution, has the advantages of good linear reproducibility, high precision, simplicity in operation and the like, and has important application value in the fields of manufacturing of printed boards, packaging substrates, integrated circuits and the like.

Description

Technical Field

[0001] The invention belongs to the field of electronic circuit manufacturing, in particular to the copper electroplating technology involved in Damascus wafer copper electroplating, packaging carriers and printed circuit boards, and specifically provides a quantitative method for copper electroplating redox type additives. Background Art

[0002] Electronic circuits and interconnect devices are an important part of the development of electronic product hardware as the basis for carrying chips and electronic components and realizing electrical interconnection. Electroplating copper technology is one of the most critical technologies in the manufacture of integrated circuits, packaging substrates and printed circuit boards (PCBs), and is also a bottleneck restricting the development of electronic packaging integration technology. In electroplating copper technology, precise control of the concentration of each component in the electroplated copper is required to stably manufacture high-quality electronic interconnection circuits. Additives play a decisive role in determining the electroplating ability, hole filling ability, macro and micro leveling performance of the electroplated copper. Among them, redox additives can reduce the surface copper thickness and improve the electroplating ability. They are a type of electroplating copper additive that has developed rapidly in recent years, such as Fe 3+ / Fe 2+ , organic quinone / organic hydroquinone compounds, phenazines, etc. In the acidic copper sulfate electroplating solution system, the role of the redox couple is to compete with the copper ion reduction reaction, reduce the current efficiency of copper deposition in the high mass transfer rate area, and further improve the electroplating throwing power in the microchannel. Its effect has the characteristics of convection dependence.

[0003] As the size of interconnect holes and fine lines continues to shrink, the requirements for electroplating solutions are getting higher and higher, and the performance and control requirements for electroplating solutions are becoming more and more stringent. Therefore, new additives will generate new quantitative (qualitative) analysis requirements. For example, Atotech has proposed adding Fe 3+ The method of improving the uniformity of electroplating by using the redox couple is applied to pulse copper electroplating, blind hole filling and other electronic packaging and high-density arbitrary interconnected PCB manufacturing. However, its disadvantages are also significant: Fe 3+ The corrosion of copper cannot be ignored, so this system has high requirements for production control equipment. Therefore, researchers continue to explore new organic redox additive systems and their precise quantitative methods in plating solutions. Organic redox electroplating copper additives belong to the new generation of redox electroplating copper additives. They not only inherit the advantages of inorganic metal redox additives in leveling effect, but also avoid the disadvantages of copper corrosion, and can even be used with phosphor copper anodes.

[0004] At present, electroplating copper additives have corresponding CVS analysis methods for quantitative analysis, but the CVS method is not suitable for the quantitative analysis of redox additives. The main reason is that the oxidation peak of copper and the oxidation peak of redox additives cannot be well distinguished; and the analysis methods for measuring electrode potential, absorbance, atomic absorption (emission) and other analytical methods for Fe-based inorganic metal additives are not suitable for organic redox additives with lower concentrations and no characteristic absorption in the visible light spectrum. Therefore, the present invention proposes a quantitative method for electroplating copper redox additives, which is also applicable to organic redox electroplating copper additives and Fe 3+ / Fe 2+ And other inorganic redox type copper plating additives. Summary of the invention

[0005] The purpose of the present invention is to provide a quantitative method for redox type additives in electroplating copper, so as to realize the concentration measurement of the redox type additives in acid sulfate electronic electroplating copper plating solution; the present invention proposes a method for measuring the consumed charge of the redox type additives based on electrochemical voltammetry, and can measure the Faraday current efficiency of the electroplating solution at the same time, and the concentration of the redox type additives in the electroplating solution is determined by calibrating the consumed charge of the redox type additives or the Faraday current efficiency in combination with the electrochemical quantitative analysis method, which has the advantages of good linear reproducibility, high precision, simple operation, etc., and has important application value in the fields of printed circuit boards, packaging substrates and integrated circuit manufacturing.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] 1. A quantitative method for electroplating copper redox additives, comprising the following steps:

[0008] Step 1. Prepare an acid sulfate electronic copper plating solution, including: copper sulfate pentahydrate, concentrated sulfuric acid, chloride ions, inhibitors, brighteners, levelers and redox additives; the concentrations of the redox additives are c1, c2, c3...c n Prepare n portions of calibration plating solution, wherein all the components of each portion of calibration plating solution are the same except for the redox additive;

[0009] Step 2. Clean the electrolytic cell and three-electrode system of the electrochemical workstation;

[0010] Step 3. Place the three-electrode system of the electrochemical workstation in the calibrated electroplating solution, keep the solution in a static state or under a fixed steady-state convection, apply a constant current to the working electrode for cathode electroplating, the electroplating time is T1, and the current density of the constant current is J1;

[0011] Step 4. After electroplating is completed, the electrolytic cell and three-electrode system of the electrochemical workstation are cleaned with deionized water;

[0012] Step 5. Place the three-electrode system of the electrochemical workstation in a dilute sulfuric acid solution, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2, and the current density of the constant current as J2;

[0013] Step 6. Calculate the charge Q consumed by the redox additive based on the cathode electroplating current density J1 and electroplating time T1, and the anode dissolution current density J2 and dissolution time T2. y :Q y =Q1-Q2, Q1=-J1×T1, Q2=J2×T2;

[0014] Step 7. Replace the calibration plating solution and repeat steps 2 to 6 to obtain the consumed charge Q of each calibration plating solution. y , to consume the charge Q y The vertical axis is the concentration of the redox additive and the horizontal axis is the standard working curve obtained by linear fitting;

[0015] Step 8. Repeat steps 2 to 6 for the electroplating solution to be measured to obtain the consumed charge Q″ of the redox additive in the electroplating solution to be measured. y , will consume charge Q″ y Substitute the standard working curve into the test solution to calculate the concentration of the redox additive.

[0016] 2. A quantitative method for electroplating copper redox additives, comprising the following steps:

[0017] Step 1. Prepare an acid sulfate electronic copper plating solution, including: copper sulfate pentahydrate, concentrated sulfuric acid, chloride ions, inhibitors, brighteners, levelers and redox additives; the concentrations of the redox additives are c1, c2, c3...c n Prepare n portions of calibration plating solution, wherein all the components of each portion of calibration plating solution are the same except for the redox additive;

[0018] Step 2. Clean the electrolytic cell and three-electrode system of the electrochemical workstation;

[0019] Step 3. Place the three-electrode system of the electrochemical workstation in the calibrated electroplating solution, keep the solution in a static state or under a fixed steady-state convection, apply a constant current to the working electrode for cathode electroplating, the electroplating time is T1, and the current density of the constant current is J1;

[0020] Step 4. After electroplating is completed, the electrolytic cell and three-electrode system of the electrochemical workstation are cleaned with deionized water;

[0021] Step 5. Place the three-electrode system of the electrochemical workstation in a dilute sulfuric acid solution, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2, and the current density of the constant current as J2;

[0022] Step 6. According to the cathode electroplating current density J1 and electroplating time T1, the anode dissolution current density J2 and dissolution time T2, the Faraday current efficiency measurement method η is calculated:

[0023]

[0024] Step 7. Replace the calibration plating solution, repeat steps 2 to 6, respectively obtain the Faraday current efficiency measurement method η of each calibration plating solution, use the Faraday current efficiency measurement method η as the ordinate and the concentration of the redox additive as the abscissa, and use linear fitting to obtain a standard working curve;

[0025] Step 8. Repeat steps 2 to 6 for the electroplating solution to be measured to obtain the Faraday current efficiency measurement method η′ of the electroplating solution to be measured, and bring the Faraday current efficiency measurement method η′ into the standard working curve to calibrate the concentration of the redox additive in the electroplating solution to be measured.

[0026] Further, for the above-mentioned first and second methods, in step 1, the acid sulfate electronic copper plating solution uses water as a solvent, including: 50g / L~120g / L copper sulfate pentahydrate, 180g~240g concentrated sulfuric acid, 0.04g / L~0.08g / L chloride ions, 0.1g / L~1g / L inhibitor, 0.001g / L~0.03g / L brightener, 0.001~1g / L leveler and 0.001g / L~10g / L redox additive.

[0027] Furthermore, for the above-mentioned first and second methods, in step 3, the current density J1 of the constant current is -0.5ASD to -4ASD, and the electroplating time T1 is 60 to 2000s; in step 5, the current density J2 of the constant current is +0.1ASD to +10ASD.

[0028] 3. A quantitative method for electroplating copper redox additives, comprising the following steps:

[0029] Step 1. preparing an acid sulfate electronic copper electroplating solution, comprising: copper sulfate pentahydrate, concentrated sulfuric acid, chloride ions, an inhibitor, a brightener, and a redox additive, wherein the concentration of the redox additive is a priori C0;

[0030] Step 2. Clean the electrochemical workstation's electrolytic cell and three-electrode system；

[0031] Step 3. Place the three-electrode system of the electrochemical workstation in the calibration plating solution, set the speed of the rotating disk electrode to 0, apply a constant voltage to the working electrode for cathode plating, the plating time is T1, and record the I-t curve, where I represents current and t represents time;

[0032] Step 4. After electroplating is completed, the three-electrode system of the electrochemical workstation is cleaned with deionized water;

[0033] Step 5. Place the three-electrode system of the electrochemical workstation in a dilute sulfuric acid solution, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2, and the current density of the constant current as J2;

[0034] Step 6. According to the I-t curve, the cathode polarization charge Q1 is obtained by current integration; according to the current density J2 and dissolution time T2 of the anode dissolution, the anode dissolution charge Q2 is calculated: Q2 = J2 × T2, and then the consumed charge Q of the redox additive is calculated. y :Q y =Q1-Q2;

[0035] Step 7. Adjust the rotating disk electrode speeds to r1, r2, r3...r n Repeat steps 2 to 6 to obtain the charge consumption Q at each rotating disk electrode speed. y , to consume the charge Q y The vertical coordinate is the half power of the rotating disk electrode speed and the horizontal coordinate is the standard working curve obtained by linear fitting, and the slope A1 of the standard working curve is obtained;

[0036] Step 8. Repeat steps 2 to 7 for the electroplating solution to be measured to obtain the working curve slope A2 corresponding to the redox additive in the electroplating solution to be measured;

[0037] Step 9. According to the slope A1 of the standard working curve and the slope A2 of the working curve, the concentration of the redox additive in the electroplating solution to be tested is calculated as:

[0038]

[0039] Wherein, B represents the concentration of the redox additive in the electroplating solution to be tested, and C0 represents the concentration of the redox additive in the calibration electroplating solution.

[0040] Further, for the above-mentioned third method, in step 1, the acid sulfate electronic copper plating solution uses water as a solvent, including: 50g / L~120g / L copper sulfate pentahydrate, 180g~240g concentrated sulfuric acid, 0.04g / L~0.08g / L chloride ions, 0.1g / L~1g / L inhibitor, 0.001g / L~0.03g / L brightener, 0.001~1g / L leveler and 0.001g / L~10g / L redox additive.

[0041] Furthermore, for the third method mentioned above, in step 3, the electroplating time T1 is 60 to 2000 s; in step 5, the current density J2 of the constant current is +0.1ASD to +10ASD.

[0042] 4. A quantitative method for electroplating copper redox additives, comprising the following steps:

[0043] Step 1. Prepare a redox additive standard solution and a dilute sulfuric acid solution with a concentration of Y, and control the electroplating solution to be tested, the redox additive standard solution, and the dilute sulfuric acid solution in an electrochemical flow cell, respectively, wherein the labeled concentration of the redox additive in the electroplating solution to be tested is C;

[0044] Step 2. introducing the electroplating solution to be tested into the electrochemical flow cell;

[0045] Step 3. Control the flow state in the flow cell to be laminar flow, apply a constant current to the working electrode for cathode electroplating, the electroplating time is T1, and the current density of the constant current is J1;

[0046] Step 4. A dilute sulfuric acid solution is introduced into the electrochemical flow cell to replace the electroplating solution to be tested in the electrochemical flow cell with a dilute sulfuric acid solution; the flow state in the flow cell is controlled to be laminar flow, a constant current is applied to the working electrode for anodic dissolution, the potential of the working electrode is monitored in real time, and the moment when the potential of the working electrode suddenly changes is recorded, and the time before the sudden change occurs is taken as the dissolution time T2, and the current density of the constant current is J2;

[0047] Step 5. Calculate the consumed charge Q of the redox additive based on the cathode electroplating current density J1 and electroplating time T1, and the anode dissolution current density J2 and dissolution time T2. y :Q y =Q1-Q2, Q1=-J1×T1, Q2=J2×T2;

[0048] Step 6. Re-introduce the electroplating solution to be tested into the electrochemical flow cell, and at the same time introduce the redox additive standard solution, and the flow rate of the redox additive standard solution is 1 / Y of the electroplating solution to be tested, so that the marked concentration of the redox additive in the electroplating solution to be tested is C+1; repeat steps 3 to 5 to obtain the consumed charge Q of the corresponding concentration of the redox additive y ;

[0049] Step 7. Repeat step 6, and in the repetitive process, adjust the flow rate of the No. 2 dosing pump to 2 / Y, 3 / Y...n / Y of the No. 1 dosing pump in turn, and the corresponding marked concentration of the redox additive in the electroplating solution to be tested is C+2, C+3...C+n, and the consumed charge Q of the corresponding concentration of the redox additive is obtained in turn. y ;

[0050] Step 8. Consume the charge Q y The vertical coordinate is the marked concentration of the redox additive and the horizontal coordinate is the horizontal coordinate. A linear fitting is used to obtain a working curve passing through the origin of the coordinate. The concentration C of the redox additive is obtained by calibration of the working curve.

[0051] Further, for the above-mentioned fourth method, in step 1, the electroplating solution to be tested is an acid sulfate electronic copper electroplating solution, which uses water as a solvent and includes: 50g / L~120g / L copper sulfate pentahydrate, 180g~240g concentrated sulfuric acid, 0.04g / L~0.08g / L chloride ions, 0.1g / L~1g / L inhibitors, 0.001g / L~0.03g / L brighteners, 0.001~1g / L levelers, and 0.001g / L~10g / L redox additives.

[0052] Furthermore, for the fourth method mentioned above, in step 3, the current density J1 of the constant current is -0.5ASD to -4ASD, and the electroplating time T1 is 60 to 2000s; in step 4, the current density J2 of the constant current is +0.1ASD to +10ASD.

[0053] In terms of working principle:

[0054] The present invention provides a quantitative method for the above four redox additives for copper electroplating, the core idea of ​​which is to calibrate the consumed charge of the redox additive, and then convert the concentration of the redox additive through the relationship between the charge and the current, and the relationship between the current and the concentration; specifically, during the cathode reaction process, the following two parallel electrochemical reactions 1 and 2 are carried out simultaneously:

[0055] Electrochemical reaction 1: A+e - =A -

[0056] Electrochemical reaction 2: Cu 2+ +2e - =Cu

[0057] Electrochemical reaction 1 is a reduction reaction of the oxidized-reduced substance A, and electrochemical reaction 2 is a reaction in which copper ions are deposited as copper;

[0058] The total reaction charge is expressed as: Q all =Q A +Q B , Q all is the total reaction charge, Q A is the power consumption of the oxidized and reduced substance A, Q B is the power consumed by copper ion B to deposit into copper; in the actual cathode reaction process, the electrochemical reaction conditions are controlled to be steady state, and the total reaction power Q all Calculated from current (read a priori on the power supply device) and time, i.e.: Q all =I0×T0, I0 is the reaction current, T0 is the reaction time;

[0059] In the anode dissolution process, the present invention uses a dilute sulfuric acid solution, and the stripping amount Q' B Theoretically equal to the amount of copper deposited Q B ; Stripping charge Q′ B It can be calculated by constant current stripping method, expressed as Q' B =I B ×T B , I B is the stripping current, T B is the stripping time; therefore, the present invention calculates the power consumption Q of the redox substance A A :Q A =Q all -Q B =Q all -Q′ B ;

[0060] Under given electrochemical test conditions (the examples list three methods: static electrode, rotating disk electrode, and microchannel electrochemical cell), the power consumption Q of the redox substance A is A It is proportional to the current of electrochemical reaction 1, and the current of electrochemical reaction 1 is proportional to the concentration of redox substance A. Therefore, based on the consumed power Q A The present invention calibrates the concentration of the redox substance A by a standard curve method or the like.

[0061] In summary, the beneficial effects of the present invention are:

[0062] The present invention provides a quantitative method for electroplating copper redox additives, and can simultaneously measure the Faraday current efficiency of the electroplating solution. The concentration of the redox additive in the electroplating solution is determined by calibrating the consumed charge of the redox additive or the Faraday current efficiency in combination with an electrochemical quantitative analysis method. The method has the advantages of good linear reproducibility, high precision, simple operation, and the like, and has important application value in the fields of printed circuit boards, packaging substrates, and integrated circuit manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 It is a schematic diagram of the principle of the quantitative method of the electroplating copper redox type additive in the present invention.

[0064] Figure 2 Schematic diagram of the principle of the electrochemical flow cell in the present invention.

[0065] Figure 3 Schematic diagram of the sampling principle of the dissolution time in the anodic dissolution process of the present invention.

[0066] Figure 4 This is a standard working curve diagram of 5,10-bis(3-sulfopropyl)phenazine inner salt in Example 1 of the present invention.

[0067] Figure 5 This is a working curve diagram of 2,7-anthraquinone disulfonic acid in Example 2 of the present invention.

[0068] Figure 6 The redox additive Fe in Example 3 of the present invention 3+ Working curve diagram.

[0069] Figure 7 This is a standard working curve diagram of 5,10-di(3-sulfopropyl)phenazine inner salt in Example 4 of the present invention. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solutions and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0071] The present invention provides a quantitative method for electroplating copper redox additives, involving the use of an electrochemical workstation, such as Figure 1 and Figure 2As shown, the electrochemical workstation has a three-electrode system, including: a working electrode (such as a platinum disk electrode, a glassy carbon electrode, etc.), a counter electrode (a platinum wire electrode, a carbon rod electrode, etc.) and a reference electrode (a silver / silver chloride electrode, a saturated calomel electrode, a mercurous sulfate electrode, etc.); in an electrochemical experiment, the working electrode (WE) serves as the core electrode, and the chemical reaction mainly occurs on the surface of the working electrode; the counter electrode (CE), also called the auxiliary electrode, forms a current loop with the working electrode, allowing current to flow in the electrochemical cell, and the main function of the counter electrode is to balance the current of the working electrode and ensure the current stability of the electrochemical workstation; the reference electrode (RE) is a voltage-stable electrode that does not participate in the reaction and is used to provide a constant reference potential, providing an accurate reference point for the potential of the working electrode, and ensuring the accuracy of the electrochemical measurement; further, as Figure 1 As shown in Figure 2, the electrochemical workstation uses a rotating disk electrode. Figure 2 As shown, the electrochemical workstation adopts an electrochemical flow cell, which is equipped with 3 liquid adding pumps and a liquid adding tank. The flow rates of several liquids can be controlled by the liquid adding pumps, and the flow state in the flow cell can be controlled.

[0072] In the present invention, the electroplating copper adopts an acid sulfate electronic electroplating copper plating solution, which uses water as a solvent and includes: 50g / L to 120g / L copper sulfate pentahydrate, 180g to 240g concentrated sulfuric acid, 0.04g / L to 0.08g / L chloride ions, 0.1g / L to 1g / L inhibitors, 0.001g / L to 0.03g / L brighteners, 0.001g / L to 1g / L levelers, and 0.001g / L to 10g / L oxygen. The redox additive is a linear polyether / branched polyether water-soluble compound, or a compound of a linear polyether / branched polyether water-soluble compound and a polyamine water-soluble compound; the brightener is a single compound containing a thiol group / disulfide bond, or a compound of two or more compounds containing a thiol group / disulfide bond; the leveler is Janus green; the redox additive (also called leveler) has redox properties and uses Fe 3+ 、V 5+ , organic quinone compounds or organic azine compounds.

[0073] In terms of working principle, based on the above-mentioned electrochemical workstation, the present invention first deposits copper on the working electrode by a cathode method, and records the total amount of electricity in the cathode process; replaces the electrochemical working solution (not containing redox additives), anode polarization strips all deposited copper, records the amount of deposited copper and converts it into electricity; subtracts the above two to obtain the reaction amount of the redox additive at the cathode, and then converts the concentration of the redox additive through the relationship between electricity and current, and the relationship between current and concentration; the present invention calculates the current (electricity) of the redox additive at the cathode interface based on the total current (electricity) of the cathode reaction being equal to the sum of the currents (electricity) of each cathode reaction, and then quantitatively calculates the concentration of the redox additive in the plating solution through the quantitative relationship between the current density and the concentration of the reactants in the steady-state and transient processes, and through the standard curve method, the single-point correction method and the like.

[0074] Specifically, the power calculation formula is expressed as:

[0075] Q=I∫dt=(I Cu +I redox )∫dt

[0076] Where Q represents charge (unit: C), Q redox Indicates the consumed charge of the redox additive, Q Cu Indicates the amount of charge consumed by copper; I indicates the current (unit: A), I redox The current representing the deposition of the redox additive, I Cu The current representing the deposition of copper;

[0077]

[0078] Where n is the number of electrons, F is the Faraday constant (96,485 C / mol), A is the area of ​​the (planar) electrode (cm2), and D is the diffusion coefficient (unit: cm -2 / s ), t represents time (unit: s);

[0079] The present invention obtains Q by anode stripping Cu , then Q redox =QQ Cu =I redox ∫dt; when t is long enough, I redox It can be considered as steady-state current, that is, Q redox ≈I redox ·t.

[0080] Implementation 1

[0081] Based on the above electrochemical workstation, this embodiment provides a quantitative method for electroplating copper redox additives, wherein the electroplating copper redox additive is specifically: 5,10-di(3-sulfopropyl)phenazine inner salt, having the structural formula:

[0082]

[0083] The quantitative method of the electroplated copper redox additive comprises the following steps:

[0084] Step 1. preparing an acid sulfate electronic copper electroplating solution;

[0085] Dissolve 375g of copper sulfate pentahydrate in 3L of deionized water, then add 0.495g of sodium chloride and 1200g of concentrated sulfuric acid in sequence, cool to room temperature and adjust the volume to 5L; then add sodium polydisulfide dipropane sulfonate as a brightener at a concentration of 2mg / L, add polyethylene glycol-8000 as an inhibitor at a concentration of 500mg / L, and add Janus green as a leveler at a concentration of 1mg / L to obtain a basic electroplating solution;

[0086] Then, 5,10-di(3-sulfopropyl)phenazine inner salt was added to the basic electroplating solution at concentrations of 2mmol / L, 5mmol / L, 10mmol / L, 20mmol / L, and 30mmol / L, respectively, as a redox additive (i.e., a leveler, which has redox properties, competes with copper ions for reduction during acid sulfate electronic electroplating copper electroplating, has a reduction potential near or higher than copper, has convection adsorption properties, and has reversible redox properties), to obtain five acid sulfate electronic electroplating copper plating solutions, which were marked as the first calibration plating solution to the fifth calibration plating solution in sequence;

[0087] Step 2. Prepare a cleaning solution by mixing 30% hydrogen peroxide and 5% dilute sulfuric acid in a volume ratio of 3:7, and use the cleaning solution to clean the three-electrode system of the electrochemical workstation;

[0088] Step 3. Place the three-electrode system of the electrochemical workstation in an acidic sulfate electronic copper electroplating solution, keep the solution in a static state (the speed of the rotating disk electrode is 0 or the electrochemical flow cell liquid pump is turned off), apply a constant current to the working electrode for cathode electroplating, and set the electroplating time T1 to 60 to 2000 s, and the current density J1 of the constant current is -0.5 ASD to -4 ASD;

[0089] Step 4. After electroplating, the three-electrode system of the electrochemical workstation is cleaned with deionized water for 5s to 100s;

[0090] Step 5. Place the three-electrode system of the electrochemical workstation in a dilute sulfuric acid solution with a mass fraction of 1% to 20%, keep the solution in a static state, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2. The current density J2 of the constant current is +0.1ASD to +10ASD;

[0091] It should be noted that: when the surface of the working electrode is covered with a copper coating, the potential of the working electrode is the potential of Cu / Cu(Ⅱ). When the copper coating is completely dissolved, the potential of the working electrode will become the potential of H2O / O2, that is, the potential of the working electrode will change suddenly, such as Figure 3 As shown, therefore, the present invention obtains the dissolution time by monitoring the potential of the working electrode and recording the moment of potential mutation; in addition, in order to make the electrochemical workstation work normally, its dissolution time can be set to a maximum value or an ideal dissolution time, that is, under the ideal condition of 100% current efficiency, the product of the current density of cathode electroplating and the electroplating time is equal to the product of the current density of anode dissolution and the dissolution time, then the ideal dissolution time can be calculated according to the current density of anode dissolution;

[0092] Step 6. Calculate the consumed charge Q of the redox additive based on the cathode electroplating current density J1 and electroplating time T1, and the anode dissolution current density J2 and dissolution time T2. y :Q y =Q1-Q2, Q1=-J1×T1, Q2=J2×T2;

[0093] Step 7. Replace the acid sulfate electronic copper plating solution in step 3, repeat steps 2 to 6, and obtain the consumed charge Q of each calibration plating solution. y , to consume the charge Q y The standard working curve is obtained by linear fitting using the least square method, as shown in Figure 2. Figure 4 As shown;

[0094] Step 8. Replace the acid sulfate electronic copper plating solution in step 3 with the plating solution to be measured (the concentration of other components in the plating solution to be measured except the redox additive is known and consistent with the calibration plating solution), repeat steps 2 to 6, and obtain the consumed charge Q″ of the redox additive in the plating solution to be measured y , will consume charge Q″ y Substitute the standard working curve into the calibration to obtain the concentration of the redox additive in the electroplating solution to be tested.

[0095] Example 2

[0096] Based on Figure 1 The electrochemical workstation shown uses a rotating disk electrode. According to the Levich equation, the limiting diffusion current density is proportional to the first power of the rotating disk electrode speed and the concentration of the redox additive, which can be expressed as:

[0097]

[0098] Among them, i l represents the limiting diffusion current density, n represents the number of electron transfers, F represents the Faraday constant, D represents the electrode area, represents the solution concentration, μ represents the diffusion coefficient, and ω represents the rotation angular velocity;

[0099] Based on this, this embodiment provides a quantitative method for electroplating copper redox additives, wherein the electroplating copper redox additive is specifically: 2,7-anthraquinone disulfonic acid, having the structural formula:

[0100]

[0101] The quantitative method of the electroplated copper redox additive comprises the following steps:

[0102] Step 1. preparing an acid sulfate electronic copper electroplating solution;

[0103] Dissolve 375g of copper sulfate pentahydrate in 3L of deionized water, then add 0.495g of sodium chloride and 1200g of concentrated sulfuric acid in sequence, cool to room temperature and adjust the volume to 5L; then add sodium polydisulfide dipropane sulfonate as a brightener at a concentration of 2mg / L, add polyethylene glycol-8000 as an inhibitor at a concentration of 500mg / L, add gena green as a leveler at a concentration of 1mg / L, and add 2,7-anthraquinone disulfonic acid as a redox additive to the basic electroplating solution at a concentration of 5mmol / L to obtain a calibrated electroplating solution;

[0104] Step 2. Prepare a cleaning solution by mixing 30% hydrogen peroxide and 5% dilute sulfuric acid in a volume ratio of 3:7, and use the cleaning solution to clean the three-electrode system of the electrochemical workstation;

[0105] Step 3. Place the three-electrode system of the electrochemical workstation in the calibration plating solution, set the speed of the rotating disk electrode to 0, apply a constant voltage to the working electrode for cathode plating, set the plating time T1 to 60 to 2000 s, and record the I-t curve (I represents current and t represents time);

[0106] Step 4. After electroplating, the three-electrode system of the electrochemical workstation is cleaned with deionized water for 5s to 100s;

[0107] Step 5. Place the three-electrode system of the electrochemical workstation in a dilute sulfuric acid solution with a mass fraction of 1% to 20%, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2. The current density J2 of the constant current is +0.1ASD to +10ASD;

[0108] Step 6. According to the I~t curve, the cathode polarization charge Q1 is obtained by current integration (Q=I∫dt); according to the current density J2 and dissolution time T2 of the anode dissolution, the anode dissolution charge Q2 is calculated, and then the consumed charge Q of the redox additive is calculated. y :Q y =Q1-Q2;

[0109] Step 7. Adjust the rotating disk electrode speed in step 3 to 225 rpm, 400 rpm, 900 rpm, 1600 rpm, 2500 rpm, and 3600 rpm, and repeat steps 2 to 6 to obtain the consumed charge Q at each rotating disk electrode speed. y , to consume the charge Q y The vertical coordinate is the half of the rotating disk electrode speed as the horizontal coordinate, and the standard working curve is obtained by least squares linear fitting, and the slope A1 of the standard working curve is obtained, such as Figure 5 As shown;

[0110] Step 8. Replace the calibration plating solution in step 3 with the plating solution to be measured (the concentrations of other components in the plating solution to be measured except for the redox additive are known and consistent with those in the calibration plating solution), repeat steps 2 to 7, and obtain the working curve slope A2 corresponding to the redox additive in the plating solution to be measured;

[0111] Step 9. According to the slope A1 of the standard working curve and the slope A2 of the working curve, the concentration of the redox additive in the electroplating solution to be tested is calculated as:

[0112]

[0113] Wherein, B represents the concentration of the redox additive in the electroplating solution to be tested, and C0 represents the concentration of the redox additive in the calibration electroplating solution (5 mmol / L in this embodiment).

[0114] Example 3

[0115] Based on Figure 2 The electrochemical workstation using an electrochemical flow cell is shown in the figure. This embodiment provides a quantitative method for electroplating copper redox additives. The electroplating copper redox additives are specifically: Fe 3+ ; Specifically include the following steps:

[0116] Step 1. Prepare Fe with a concentration of 1000 g / L 3+ standard solution and 1% to 20% dilute sulfuric acid solution, and mix the electroplating solution to be tested, Fe 3+ The standard solution and the dilute sulfuric acid solution are added to the No. 1, No. 2, and No. 3 liquid adding tanks of the electrochemical flow cell respectively, and each liquid adding tank is equipped with a liquid adding pump with the same number; the electroplating solution to be tested in this embodiment is prepared as follows:

[0117] Dissolve 375g of copper sulfate pentahydrate in 3L of deionized water, then add 0.495g of sodium chloride and 1200g of concentrated sulfuric acid in turn, cool to room temperature and adjust the volume to 5L; then add sodium polydisulfide dipropane sulfonate as a brightener at a concentration of 2mg / L, add polyethylene glycol-8000 as an inhibitor at a concentration of 500mg / L, add Jiana green as a leveler at a concentration of 1mg / L, and add Fe to the basic electroplating solution at a concentration of C g / L. 3+ As a redox additive, obtaining a test electroplating solution, wherein C is the labeled concentration of the redox additive;

[0118] Step 2. Turn on the No. 1 liquid adding pump, keep the No. 2 liquid adding pump and the No. 3 liquid adding pump closed, and introduce the electroplating solution to be tested into the electrochemical flow cell;

[0119] Step 3. Control the flow state in the flow cell to be laminar flow, apply a constant current to the working electrode for cathode electroplating, set the electroplating time T1 to 60 to 2000 s, and the current density J1 of the constant current to -0.5 ASD to -4 ASD;

[0120] Step 4. After the electroplating is completed, turn off the No. 1 dosing pump, keep the No. 2 dosing pump turned off, and turn on the No. 3 dosing pump to replace the electroplating solution to be tested in the electrochemical flow cell with a dilute sulfuric acid solution; control the flow state in the flow cell to be laminar flow, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2, and the current density J2 of the constant current is +0.1ASD to +10ASD;

[0121] Step 5. Calculate the consumed charge Q of the redox additive based on the cathode electroplating current density J1 and electroplating time T1, and the anode dissolution current density J2 and dissolution time T2. y :Q y =Q1-Q2, Q1=-J1×T1, Q2=J2×T2;

[0122] Step 6. Restart the No. 1 dosing pump, start the No. 2 dosing pump, and close the No. 3 dosing pump. At the same time, set the flow rate of the No. 2 dosing pump to 1 / 1000 of the No. 1 dosing pump. At this time, the marked concentration of the redox additive in the electroplating solution to be tested is C+1; repeat steps 3 to 5 to obtain the consumed charge Q of the corresponding concentration of the redox additive. y ;

[0123] Step 7. Repeat step 6, and in the repetitive process, adjust the flow rate of the No. 2 dosing pump to 2 / 1000, 3 / 1000, 4 / 1000, 5 / 1000, and 6 / 1000 of the No. 1 dosing pump in sequence, and the corresponding marked concentrations of the redox additive in the electroplating solution to be tested are C+2, C+3, C+4, C+5, and C+6, and the consumed charge Q of the corresponding concentration of the redox additive is obtained in sequence. y ;

[0124] Step 8. Consume the charge Q y The vertical axis is the concentration of the redox additive, and the horizontal axis is the labeled concentration. A linear fitting is used to obtain a working curve passing through the origin of the coordinate system, such as Figure 6 As shown, the concentration of the redox additive C g / L was obtained by calibration of the working curve.

[0125] Example 4

[0126] This embodiment provides a quantitative method for electroplating copper redox additives, wherein steps 1 to 5 are the same as those in embodiment 1, except that:

[0127] Step 6. According to the cathode electroplating current density J1 and electroplating time T1, the anode dissolution current density J2 and dissolution time T2, the Faraday current efficiency measurement method η is calculated:

[0128]

[0129] Wherein, J1 represents the current density of cathode plating, T1 represents the plating time of cathode plating, J2 represents the current density of anodic dissolution, and T2 represents the dissolution time of anodic dissolution;

[0130] Step 7. Replace the acid sulfate electronic copper electroplating solution in step 3, repeat steps 2 to 6, and obtain the Faraday current efficiency measurement method η of each calibration electroplating solution. Use the Faraday current efficiency measurement method η as the ordinate and the concentration of the redox additive as the abscissa to obtain the standard working curve using the least squares linear fitting method, such as Figure 7 As shown;

[0131] Step 8. Replace the acid sulfate electronic copper electroplating solution in step 3 with the plating solution to be measured (the concentrations of other components in the plating solution to be measured except the redox additive are known and consistent with the calibration plating solution), repeat steps 2 to 6, obtain the Faraday current efficiency measurement method η′ of the plating solution to be measured, bring the Faraday current efficiency measurement method η′ into the standard working curve, and calibrate to obtain the concentration of the redox additive in the plating solution to be measured.

[0132] In summary, the present invention proposes a method for measuring the consumed charge of a redox additive based on an electrochemical workstation, based on which the concentration of the redox additive can be quantified; on the other hand, when the concentration of the redox additive is known, the Faraday current efficiency of the prepared acid sulfate electronic copper electroplating solution can be measured; the two complement each other, assisting in completing the plating solution design and process parameter design in the acid sulfate electronic copper electroplating technology, and improving the electroplating performance.

[0133] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A quantitative method for electroplating copper redox additives, comprising the following steps: Step 1. Prepare an acid sulfate electronic copper plating solution, including: copper sulfate pentahydrate, concentrated sulfuric acid, chloride ions, inhibitors, brighteners, levelers and redox additives; the concentrations of the redox additives are c1, c2, c3...c n Prepare n portions of calibration plating solution, wherein all the components of each portion of calibration plating solution are the same except for the redox additive; Step 2. Clean the electrolytic cell and three-electrode system of the electrochemical workstation; Step 3. Place the three-electrode system of the electrochemical workstation in the calibrated electroplating solution, keep the solution in a static state or under a fixed steady-state convection, apply a constant current to the working electrode for cathode electroplating, the electroplating time is T1, and the current density of the constant current is J1; Step 4. After electroplating is completed, the electrolytic cell and three-electrode system of the electrochemical workstation are cleaned with deionized water; Step 5. Place the three-electrode system of the electrochemical workstation in a dilute sulfuric acid solution, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2, and the current density of the constant current as J2; Step 6. Calculate the charge Q consumed by the redox additive based on the cathode electroplating current density J1 and electroplating time T1, and the anode dissolution current density J2 and dissolution time T2. y :Q y =Q1-Q2, Q1=-J1×T1, Q2=J2×T2; Step 7. Replace the calibration plating solution and repeat steps 2 to 6 to obtain the consumed charge Q of each calibration plating solution. y , to consume the charge Q y The vertical axis is the concentration of the redox additive and the horizontal axis is the standard working curve obtained by linear fitting; Step 8. For the electroplating solution to be measured, repeat steps 2 to 6 to obtain the consumed charge Qy″ of the redox additive in the electroplating solution to be measured, substitute the consumed charge Qy″ into the standard working curve, and calculate the concentration of the redox additive in the electroplating solution to be measured.

2. A quantitative method for electroplating copper redox additives, comprising the following steps: Step 1. Prepare an acid sulfate electronic copper plating solution, including: copper sulfate pentahydrate, concentrated sulfuric acid, chloride ions, inhibitors, brighteners, levelers and redox additives; the concentrations of the redox additives are c1, c2, c3...c n Prepare n portions of calibration plating solution, wherein all the components of each portion of calibration plating solution are the same except for the redox additive; Step 2. Clean the electrolytic cell and three-electrode system of the electrochemical workstation; Step 3. Place the three-electrode system of the electrochemical workstation in the calibrated electroplating solution, keep the solution in a static state or under a fixed steady-state convection, apply a constant current to the working electrode for cathode electroplating, the electroplating time is T1, and the current density of the constant current is J1; Step 4. After electroplating is completed, the electrolytic cell and three-electrode system of the electrochemical workstation are cleaned with deionized water; Step 5. Place the three-electrode system of the electrochemical workstation in a dilute sulfuric acid solution, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2, and the current density of the constant current as J2; Step 6. According to the cathode electroplating current density J1 and electroplating time T1, the anode dissolution current density J2 and dissolution time T2, the Faraday current efficiency measurement method η is calculated: Step 7. Replace the calibration plating solution, repeat steps 2 to 6, respectively obtain the Faraday current efficiency measurement method η of each calibration plating solution, use the Faraday current efficiency measurement method η as the ordinate and the concentration of the redox additive as the abscissa, and use linear fitting to obtain a standard working curve; Step 8. Repeat steps 2 to 6 for the electroplating solution to be measured to obtain the Faraday current efficiency measurement method η′ of the electroplating solution to be measured, and bring the Faraday current efficiency measurement method η′ into the standard working curve to calibrate the concentration of the redox additive in the electroplating solution to be measured.

3. The quantitative method of the redox additive for electroplating copper according to claim 1 or claim 2, characterized in that: In step 1, the acid sulfate electronic copper electroplating solution uses water as a solvent and includes: 50g / L to 120g / L copper sulfate pentahydrate, 180g to 240g concentrated sulfuric acid, 0.04g / L to 0.08g / L chloride ions, 0.1g / L to 1g / L inhibitors, 0.001g / L to 0.03g / L brighteners, 0.001g / L to 0.1g / L levelers, and 0.001g / L to 10g / L redox additives.

4. The quantitative method of the redox additive for electroplating copper according to claim 1 or claim 2, characterized in that: In step 3, the current density J1 of the constant current is -0.5ASD to -4ASD, and the electroplating time T1 is 60 to 2000s; in step 5, the current density J2 of the constant current is +0.1ASD to +10ASD.

5. A quantitative method for electroplating copper redox additives, comprising the following steps: Step 1. preparing an acid sulfate electronic copper electroplating solution, comprising: copper sulfate pentahydrate, concentrated sulfuric acid, chloride ions, an inhibitor, a brightener, and a redox additive, wherein the concentration of the redox additive is a priori C0; Step 2. Clean the electrochemical workstation's electrolytic cell and three-electrode system ； Step 3. Place the three-electrode system of the electrochemical workstation in the calibration plating solution, set the speed of the rotating disk electrode to 0, apply a constant voltage to the working electrode for cathode plating, the plating time is T1, and record the I-t curve, where I represents current and t represents time; Step 4. After electroplating is completed, the three-electrode system of the electrochemical workstation is cleaned with deionized water; Step 5. Place the three-electrode system of the electrochemical workstation in a dilute sulfuric acid solution, apply a constant current to the working electrode for anodic dissolution, monitor the potential of the working electrode in real time, record the moment when the potential of the working electrode suddenly changes, and take the time before the sudden change as the dissolution time T2, and the current density of the constant current as J2; Step 6. According to the I-t curve, the cathode polarization charge Q1 is obtained by current integration; according to the current density J2 and dissolution time T2 of the anode dissolution, the anode dissolution charge Q2 is calculated: Q2 = J2 × T2, and then the consumed charge Q of the redox additive is calculated. y :Q y =Q1-Q2; Step 7. Adjust the rotating disk electrode speeds to r1, r2, r3...r n Repeat steps 2 to 6 to obtain the consumed charge Q at each rotating disk electrode speed. y , to consume the charge Q y The vertical coordinate is the half power of the rotating disk electrode speed and the horizontal coordinate is the standard working curve obtained by linear fitting, and the slope A1 of the standard working curve is obtained; Step 8. Repeat steps 2 to 7 for the electroplating solution to be measured to obtain the working curve slope A2 corresponding to the redox additive in the electroplating solution to be measured; Step 9. According to the slope A1 of the standard working curve and the slope A2 of the working curve, the concentration of the redox additive in the electroplating solution to be tested is calculated as: Wherein, B represents the concentration of the redox additive in the electroplating solution to be tested, and C0 represents the concentration of the redox additive in the calibration electroplating solution.

6. The quantitative method of the redox additive for electroplating copper according to claim 5, characterized in that: In step 1, the acid sulfate electronic copper electroplating solution uses water as a solvent and includes: 50g / L to 120g / L copper sulfate pentahydrate, 180g to 240g concentrated sulfuric acid, 0.04g / L to 0.08g / L chloride ions, 0.1g / L to 1g / L inhibitors, 0.001g / L to 0.03g / L brighteners, 0.001g / L to 1g / L levelers, and 0.001g / L to 10g / L redox additives.

7. The quantitative method of the redox additive for copper electroplating according to claim 5, characterized in that: In step 3, the electroplating time T1 is 60 to 2000 s; in step 5, the current density J2 of the constant current is +0.1ASD to +10ASD.

8. A quantitative method for electroplating copper redox additives, comprising the following steps: Step 1. Prepare a redox additive standard solution and a dilute sulfuric acid solution with a concentration of Y, and control the electroplating solution to be tested, the redox additive standard solution, and the dilute sulfuric acid solution in an electrochemical flow cell, respectively, wherein the labeled concentration of the redox additive in the electroplating solution to be tested is C; Step 2. introducing the electroplating solution to be tested into the electrochemical flow cell; Step 3. Control the flow state in the flow cell to be laminar flow, apply a constant current to the working electrode for cathode electroplating, the electroplating time is T1, and the current density of the constant current is J1; Step 4. A dilute sulfuric acid solution is introduced into the electrochemical flow cell to replace the electroplating solution to be tested in the electrochemical flow cell with a dilute sulfuric acid solution; the flow state in the flow cell is controlled to be laminar flow, a constant current is applied to the working electrode for anodic dissolution, the potential of the working electrode is monitored in real time, and the moment when the potential of the working electrode suddenly changes is recorded, and the time before the sudden change occurs is taken as the dissolution time T2, and the current density of the constant current is J2; Step 5. Calculate the consumed charge Q of the redox additive based on the cathode electroplating current density J1 and electroplating time T1, and the anode dissolution current density J2 and dissolution time T2. y :Q y =Q1-Q2, Q1=-J1×T1, Q2=J2×T2; Step 6. Re-introduce the electroplating solution to be tested into the electrochemical flow cell, and at the same time introduce the redox additive standard solution, and the flow rate of the redox additive standard solution is 1 / Y of the electroplating solution to be tested, so that the marked concentration of the redox additive in the electroplating solution to be tested is C+1; repeat steps 3 to 5 to obtain the consumed charge Q of the corresponding concentration of the redox additive y ; Step 7. Repeat step 6, and in the repetitive process, adjust the flow rate of the No. 2 dosing pump to 2 / Y, 3 / Y...n / Y of the No. 1 dosing pump in turn, and the corresponding marked concentration of the redox additive in the electroplating solution to be tested is C+2, C+3...C+n, and the consumed charge Q of the corresponding concentration of the redox additive is obtained in turn. y ; Step 8. Consume the charge Q y The vertical coordinate is the marked concentration of the redox additive and the horizontal coordinate is the horizontal coordinate. A linear fitting is used to obtain a working curve passing through the origin of the coordinate. The concentration C of the redox additive is obtained by calibration of the working curve.

9. The quantitative method of the redox additive for copper electroplating according to claim 8, characterized in that: In step 1, the electroplating solution to be tested is an acid sulfate electronic copper electroplating solution, which uses water as a solvent and includes: 50g / L to 120g / L copper sulfate pentahydrate, 180g to 240g concentrated sulfuric acid, 0.04g / L to 0.08g / L chloride ions, 0.1g / L to 1g / L inhibitors, 0.001g / L to 0.03g / L brighteners, 0.001g / L to 1g / L levelers, and 0.001g / L to 10g / L redox additives.

10. The quantitative method of the redox additive for electroplating copper according to claim 8, characterized in that: In step 3, the current density J1 of the constant current is -0.5ASD to -4ASD, and the electroplating time T1 is 60 to 2000s; in step 4, the current density J2 of the constant current is +0.1ASD to +10ASD.

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