Electroplating apparatus

Abstract

Provided in the present application is an electroplating apparatus, comprising an electroplating chamber and a metal unit. The metal unit is disposed in an anode chamber of the electroplating chamber. The electroplating chamber contains an electroplating solution comprising ions of a metal corresponding to the metal unit. An inert electrode is disposed in the electroplating chamber and configured to be electrically connected to the metal unit during a non-plating period of a substrate to form a circuit. In the circuit, the inert electrode serves as an anode, and the metal unit serves as a cathode. A preset voltage is applied between the inert electrode and the metal unit, wherein the preset voltage is lower than a threshold voltage at which an electrochemical reaction occurs in the metal unit during the non-plating period of the substrate. According to the electroplating apparatus in the present application, during the non-plating period, the inert electrode serves as the anode, and the metal unit serves as the cathode. The voltage applied between the inert electrode and the metal unit is lower than the threshold voltage at which the electrochemical reaction occurs in the metal unit during the non-plating period of the substrate, so that the metal unit is in a relatively weak cathodic polarization state, thereby suppressing self-dissolution of the metal unit in the electroplating solution.

Description

Electroplating equipment Technical Field

[0001] This application relates to the field of semiconductor equipment technology, and in particular to an electroplating apparatus. Background Technology

[0002] In cobalt electroplating, the main components of the anolyte are cobalt sulfate (CoSO4), sulfuric acid (H2SO4), and boric acid (H3BO3), while the main components of the cathode plating solution are also cobalt sulfate (CoSO4), sulfuric acid (H2SO4), boric acid (H3BO3), and additives. The entire plating solution system is acidic. Because metallic cobalt has a stronger reducing power than hydrogen, elemental cobalt can displace hydrogen ions in acidic solutions. Therefore, when not electroplating, the cobalt block at the anode can react with hydrogen ions in the plating solution, causing hydrogen ion consumption and cobalt dissolution. This phenomenon leads to an increase in the pH value of the plating solution and waste of cobalt. Besides cobalt, other metal anodes that are more reactive than hydrogen in acidic solutions (such as nickel and tin) also exhibit this problem when not electroplating.

[0003] Due to the chemical properties of cobalt and the electroplating solution, sulfuric acid is currently typically added to compensate for the hydrogen ions consumed by the cobalt anode, thus suppressing the increase in pH value. However, this still results in the waste of cobalt blocks and sulfuric acid. In addition, if sulfuric acid is not replenished in time or the amount of sulfuric acid replenished is insufficient, it will lead to excessive consumption of hydrogen ions, and may even cause cobalt ions to precipitate out in the form of cobalt hydroxide, clogging the filter, preventing the plating solution from circulating, and causing the filter and the entire plating solution to be scrapped. It takes a long time to restore the equipment to normal production status. If too much sulfuric acid is added, it will cause abnormal fluctuations in the concentration of hydrogen ions and cobalt ions at the anode, which will then affect the electrochemical behavior of the cathode area during electroplating. Summary of the Invention

[0004] The technical problem to be solved by this application is to overcome the defect in the prior art where the anode metal unit reacts with hydrogen ions in the plating solution and causes the metal unit to self-dissolve when the electroplating operation is not being performed, and to provide an electroplating device.

[0005] This application solves the above-mentioned technical problems through the following technical solution:

[0006] This application provides an electroplating apparatus, which includes an electroplating chamber and a metal unit. The metal unit is placed in the anode chamber of the electroplating chamber, and the electroplating chamber contains an electroplating solution containing ions of the metal corresponding to the metal unit, for electroplating the metal onto the substrate during substrate plating.

[0007] An inert electrode is provided in the electroplating chamber. The inert electrode is configured to be electrically connected to the metal unit during the non-plating period of the substrate to form a circuit. In the circuit, the inert electrode acts as the anode and the metal unit acts as the cathode. A preset voltage is applied between the inert electrode and the metal unit. The preset voltage is configured to be lower than the threshold voltage at which the metal unit undergoes an electrochemical reaction during the non-plating period of the substrate.

[0008] The positive and progressive effects of this application are as follows:

[0009] In the electroplating apparatus of this application, an inert electrode acts as the anode, and a metal unit acts as the cathode. The voltage applied between the inert electrode and the metal unit is lower than the threshold voltage at which the metal unit undergoes an electrochemical reaction during the non-plating period of the substrate, resulting in the metal unit being in a weak cathodic polarization state. Firstly, this reduces or avoids the reaction between the metal unit and hydrogen ions in the electroplating solution, inhibits the self-dissolution of the metal unit in the electroplating solution, and prevents an increase in the pH value of the electroplating solution. Secondly, because the voltage applied between the inert electrode and the metal unit is lower than the threshold voltage for an electrochemical reaction, significant electrochemical reactions can be avoided, thereby preventing metal ions in the plating solution from transforming into metal precipitates that affect the stability of the component concentration in the electroplating solution, and also preventing hydrogen evolution reactions. Thirdly, because the weak polarization voltage does not cause significant electrochemical reactions, the current between the metal unit and the inert electrode is very small, preventing a large consumption of electrical energy.

[0010] Overview of the attached figures

[0011] Figure 1 is a schematic diagram of the structure of an electroplating apparatus according to an embodiment of this application.

[0012] Figure 2 is a schematic diagram of the structure inside the anode cavity according to an embodiment of this application.

[0013] Preferred embodiments of this application

[0014] The present application is further illustrated below by way of embodiments, but this does not limit the present application to the scope of the following embodiments.

[0015] As shown in Figures 1 and 2, this application provides an electroplating apparatus, including an electroplating chamber 1 and a metal unit 20. The metal unit 20 is placed in the anode chamber 11 of the electroplating chamber 1. The electroplating chamber 1 contains an electroplating solution containing ions of the metal corresponding to the metal unit 20, for electroplating the metal onto the substrate 8 during plating. An inert electrode 30 is disposed in the electroplating chamber 1. The inert electrode 30 is configured to be electrically connected to the metal unit 20 during non-plating periods of the substrate 8 to form a circuit. In this circuit, the inert electrode 30 acts as the anode, and the metal unit 20 acts as the cathode. A preset voltage is applied between the inert electrode 30 and the metal unit 20. The preset voltage is configured to be lower than the threshold voltage at which the metal unit 20 undergoes an electrochemical reaction during non-plating periods of the substrate 8. The threshold voltage at which the electrochemical reaction occurs can be measured using existing methods. Specifically, during non-plating periods of the substrate 8, energization is applied between the inert electrode 30 and the metal unit 20, and the voltage between them is gradually increased. While adjusting the voltage, the circuit current is observed to obtain a current-voltage curve. By observing the shape of the volt-ampere curve, the loop current is very small before the loop voltage reaches the threshold voltage of the electrochemical reaction. Only after the loop voltage exceeds the threshold voltage of the electrochemical reaction does the loop current increase significantly. This allows us to obtain the threshold voltage for the electrochemical reaction to occur. In other words, if the voltage between the inert electrode 30 and the metal unit 20 is lower than the threshold voltage for the electrochemical reaction, the electrochemical reaction hardly occurs (or occurs very slowly); if the voltage between the inert electrode 30 and the metal unit 20 is higher than the threshold voltage for the electrochemical reaction, a significant electrochemical reaction will occur. The threshold voltage serves as the voltage boundary between when the electrochemical reaction almost does not occur and when it becomes significant.

[0016] During plating, an electric current is applied between the metal unit 20 in the anode chamber 11 and the substrate 8 in the cathode chamber 12 to electroplate the metal corresponding to the metal unit 20 onto the substrate 8. During non-plating periods (i.e., when no electroplating is being performed), the electrical connection between the metal unit 20 in the anode chamber 11 and the substrate 8 is disconnected, and the metal unit 20 is electrically connected to the inert electrode 30 to form a circuit. The inert electrode 30 acts as the anode, and the metal unit 20 acts as the cathode. The voltage applied between the inert electrode 30 and the metal unit 20 is lower than the threshold voltage at which the metal unit 20 undergoes an electrochemical reaction during the non-plating period on the substrate 8, resulting in the metal unit 20 being in a weaker cathodic polarization state. Firstly, this reduces or avoids the reaction between the metal unit 20 and hydrogen ions in the plating solution, inhibits the self-dissolution of the metal unit 20 in the plating solution, and prevents an increase in the pH value of the plating solution. Secondly, the voltage applied between the inert electrode 30 and the metal unit 20 is lower than the threshold voltage for electrochemical reactions, thus preventing significant electrochemical reactions and avoiding the transformation of metal ions in the plating solution into metal precipitates that could affect the stability of the plating solution's component concentration. It also prevents hydrogen evolution reactions. Thirdly, because the weak polarization voltage does not induce significant electrochemical reactions, the current between the metal unit 20 and the inert electrode 30 is very small, preventing excessive energy consumption.

[0017] In this embodiment, the metal unit 20 is a metal block. In other embodiments, the metal unit 20 may be metal particles.

[0018] In some embodiments, the metal unit 20 is made of cobalt. The main components of the anolyte in the anode chamber 11 are CoSO4, H2SO4, and H3BO3, and the main components of the catholyte in the cathode chamber 12 are CoSO4, H2SO4, H3BO3, and additives. The anode chamber 11 and the cathode chamber 12 are separated by an ion exchange membrane 7. In other embodiments, the metal unit 20 may be made of nickel or tin, or other metal anodes that are more reactive than hydrogen in acidic plating solutions.

[0019] In some embodiments, the inert electrode 30 may be made of titanium. In other embodiments, the inert electrode 30 may be made of platinum or graphite, or may include any combination of titanium, platinum, or graphite, or other materials that do not react with the electroplating solution.

[0020] In this embodiment, as shown in FIG1, the inert electrode 30 is disposed within the anode cavity 11. By disposing of the inert electrode 30 within the anode cavity 11, the inert electrode 30 is placed in the anodic plating solution environment, which can reduce or avoid the situation where additives discharge on the surface of the inert electrode 30, leading to additive failure and an increase in the oxygen content of the plating solution.

[0021] In other embodiments, the inert electrode 30 may be disposed within the cathode cavity 12.

[0022] In some embodiments, as shown in FIG2, the inert electrode 30 is an annular electrode, which surrounds the outer periphery of the metal unit 20, and the inert electrode 30 and the metal unit 20 are arranged in concentric circles. By maintaining a consistent spacing between the inert electrode 30, which serves as the anode, and the metal unit 20, which serves as the cathode, it is helpful to achieve a uniform electric field distribution so that the reaction can be precisely controlled.

[0023] In some embodiments, as shown in FIG1, the anode cavity 11 includes an anode cavity housing 113. The bottom of the anode cavity housing 113 is provided with a first mounting hole 111 and a second mounting hole 112. The two ends of the power supply of the circuit extend into the anode cavity 11 through the first mounting hole 111 and the second mounting hole 112 respectively to connect the metal unit 20 and the inert electrode 30. Specifically, terminals are installed on the first mounting hole 111 and the second mounting hole 112 respectively to realize the connection of the circuit and to prevent the electroplating solution in the anode cavity 11 from flowing out.

[0024] In some embodiments, the anode chamber 11 includes an anode chamber housing 113, and the electroplating apparatus further includes a titanium plate 5. The titanium plate 5 is mounted on the bottom of the anode chamber housing 113, and the metal unit 20 is mounted on the titanium plate 5. The two ends of the power supply of the circuit are respectively connected to the titanium plate 5 and the inert electrode 30. Using the titanium plate 5 as the mounting base for the metal unit 20 can avoid contamination of the electroplating solution.

[0025] In some embodiments, as shown in FIG2, the anode cavity 11 includes at least a first electric field region 114 and a second electric field region 115 arranged concentrically. The metal unit 20 includes a first metal unit 21 and a second metal unit 22, with the second metal unit 22 surrounding the outer periphery of the first metal unit 21. The inert electrode 30 includes a first inert electrode 31 and a second inert electrode 32. The first metal unit 21 and the first inert electrode 31 are located within the first electric field region 114 and are electrically connected during non-plating periods of the substrate 8 to form a first circuit. The second metal unit 22 and the second inert electrode 32 are located within the second electric field region 115 and are electrically connected during non-plating periods of the substrate 8 to form a second circuit. By providing multiple metal units, each metal unit 20 can be energized with the substrate 8 to form a circuit, thereby enabling separate control of the electric field in different regions within the electroplating cavity 1. This helps control the distribution of the electric field within the electroplating cavity 1, reduces edge effects, and enables the acquisition of a uniform and smooth electroplated layer during substrate 8 plating. Based on the configuration of multiple metal units 20, a corresponding inert electrode 30 is provided for each metal unit 20.

[0026] Furthermore, referring to Figure 2, the first metal unit 21, the first inert electrode 31, the second metal unit 22, and the second inert electrode 32 are arranged sequentially from the center to the edge along the radial direction of the bottom wall of the anode cavity housing 113, and the first metal unit 21, the first inert electrode 31, the second metal unit 22, and the second inert electrode 32 are arranged in concentric circles.

[0027] In other embodiments, the first metal unit 21, the first inert electrode 31, the second inert electrode 32, and the second metal unit 22 are arranged sequentially from the center to the edge along the radial direction of the bottom wall of the anode cavity housing 113, and the first metal unit 21, the first inert electrode 31, the second inert electrode 32, and the second metal unit 22 are arranged in concentric circles.

[0028] Furthermore, as shown in Figure 2, the first metal unit 21 includes four sector-shaped metal units, which are arranged in a circle.

[0029] In some embodiments, during plating, there are two third power supplies (not shown) for energizing the metal unit 20 and the substrate 8. The first metal unit 21 in the anode cavity 11 and the substrate 8 are energized through one of the third power supplies, and the second metal unit 22 in the anode cavity 11 and the substrate 8 are energized through the other third power supply. During non-plating periods, both third power supplies are disconnected, and the first metal unit 21 and the first inert electrode 31 in the anode cavity 11 are energized through the first power supply 41, while the second metal unit 22 and the second inert electrode 32 in the anode cavity 11 are energized through the second power supply 42.

[0030] In other embodiments, during non-plating periods, the first metal unit 21 and the first inert electrode 31, and the second metal unit 22 and the second inert electrode 32 can also be energized by a third power supply. Specifically, if the third power supply supports reverse output function, the polarity of the third power supply is reversed, the connection points between the two third power supplies and the substrate 8 are directly disconnected, and they are respectively connected to the first inert electrode 31 and the second inert electrode 32; if the third power supply does not support reverse output function, an additional relay or contactor is required to reverse the polarity. How to install the relay or contactor is well known to those skilled in the art and will not be described in detail here.

[0031] In some embodiments, as shown in Figures 1 and 2, the electroplating apparatus further includes a baffle 6 disposed between the first inert electrode 31 and the second metal unit 22. The baffle 6 serves to separate and protect the first metal unit 21 and the second metal unit 22, preventing mutual interference between them due to the connection of the electroplating solution. The baffle 6 is made of an insulating material.

[0032] While specific embodiments of this application have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this application is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this application, but all such changes and modifications fall within the scope of protection of this application.

Claims

1. An electroplating apparatus, characterized in that, It includes an electroplating chamber and a metal unit, wherein the metal unit is placed in the anode chamber of the electroplating chamber, and the electroplating chamber contains an electroplating solution containing ions of the metal corresponding to the metal unit, for electroplating the metal onto the substrate during substrate plating. An inert electrode is provided in the electroplating chamber. The inert electrode is configured to be electrically connected to the metal unit during the non-plating period of the substrate to form a circuit. In the circuit, the inert electrode acts as the anode and the metal unit acts as the cathode. A preset voltage is applied between the inert electrode and the metal unit. The preset voltage is configured to be lower than the threshold voltage at which the metal unit undergoes an electrochemical reaction during the non-plating period of the substrate.

2. The electroplating apparatus as described in claim 1, characterized in that, The inert electrode is disposed inside the anode cavity.

3. The electroplating apparatus as described in claim 2, characterized in that, The inert electrode is a ring-shaped electrode that surrounds the outer periphery of the metal unit, and the inert electrode and the metal unit are arranged in concentric circles.

4. The electroplating apparatus as described in claim 2, characterized in that, The anode cavity includes an anode cavity housing. The bottom of the anode cavity housing is provided with a first mounting hole and a second mounting hole. The two ends of the power supply of the circuit extend into the anode cavity through the first mounting hole and the second mounting hole, respectively, to connect to the metal unit and the inert electrode.

5. The electroplating apparatus as described in claim 2, characterized in that, The anode cavity includes an anode cavity housing, and the electroplating apparatus further includes a titanium plate, which is mounted on the bottom of the anode cavity housing, and the metal unit is mounted on the titanium plate.

6. The electroplating apparatus as described in claim 3, characterized in that, The anode cavity includes at least a first electric field region and a second electric field region arranged in concentric circles. The metal unit includes a first metal unit and a second metal unit, with the second metal unit surrounding the outer periphery of the first metal unit. The inert electrode includes a first inert electrode and a second inert electrode. The first metal unit and the first inert electrode are located within the first electric field region and are electrically connected during the non-plating period of the substrate to form a first circuit; the second metal unit and the second inert electrode are located within the second electric field region and are electrically connected during the non-plating period of the substrate to form a second circuit.

7. The electroplating apparatus as described in claim 6, characterized in that, It also includes a retaining wall, which is disposed between the first electric field region and the second electric field region.

8. The electroplating apparatus according to any one of claims 1-7, characterized in that, The metal unit includes any one of cobalt, nickel, or tin.

9. The electroplating apparatus according to any one of claims 1-7, characterized in that, The material of the inert electrode includes any one or more of titanium, platinum, or graphite.

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