JP4667968B2 - Plating apparatus, plating process management apparatus, plating method, and plating process management method - Google Patents

Description

  The present invention relates to a plating apparatus to which an electrolytic plating method is applied, a plating process management apparatus, a plating method, and a plating process management method, and more particularly, a plating apparatus for obtaining a uniform plating thickness on a substrate to be plated. The present invention relates to a plating processing management device, a plating method, and a plating processing management method.

  In recent years, electronic devices such as mobile phone information terminals have been reduced in size and weight, and in response, semiconductor integrated circuits incorporated in these electronic devices themselves have been required to be reduced in size and weight and mounted in high density. Yes.

  As an effective method for achieving miniaturization and high-density mounting of a semiconductor integrated circuit or the like (hereinafter referred to as a semiconductor device), a method using a protruding electrode for mounting (so-called bump electrode) is widely used. In this method, a bump electrode made of gold (Au) is formed at a predetermined position on the surface of the semiconductor device by applying a plating technique, and the semiconductor device is directly mounted on a mounting substrate using the bump electrode. Yes.

  A process flow for forming the bump electrodes is shown in FIG. FIG. 3A is a cross-sectional view showing the configuration of the semiconductor substrate before the bump electrode is formed. FIGS. 3B to 3E are cross-sectional views showing steps until a bump electrode is formed on the semiconductor substrate shown in FIG.

  As shown in FIG. 3A, an aluminum pad and a protective film are provided on the surface of the semiconductor substrate, and many semiconductor devices are incorporated. Then, as shown in FIG. 3B, first, a base metal is deposited on the surface of a semiconductor substrate in which a large number of semiconductor devices are incorporated. Then, as shown in FIG. 3 (c), a photoresist is applied, the photoresist film at the location where the bump electrode is to be formed is opened, and the base metal film previously deposited in FIG. 3 (b) is formed. Expose. Next, as shown in FIG. 3D, the semiconductor substrate is immersed in a plating solution, and a plating metal, for example, gold (Au) is deposited on the underlying metal film exposed at the opening of the photoresist film. Then, as shown in FIG. 3E, the resist film is removed to form bump electrodes on the semiconductor substrate.

  There are two plating methods, an electrolytic plating method and an electroless plating method. Electrolytic plating is usually used for forming the bump electrodes. In the electroplating method, a substrate to be plated is connected to a cathode, the substrate and the anode electrode are opposed to each other and immersed in a plating solution, and a predetermined DC voltage is applied to apply a plating metal to a predetermined position on the substrate. It is the method of making it precipitate. Compared with the electroless plating method, this electrolytic plating method has a remarkably fast plating growth rate and a large degree of freedom in combination of the base metal and the plating solution. A thick plating layer can be prepared in advance.

  Further, as described above, in the method of mounting a semiconductor device on a mounting substrate using bump electrodes, a semiconductor is used to ensure the connection strength between the bump electrodes and the mounting substrate and to ensure the reliability of the mounting substrate related to the connection. It is essential that the height of the bump electrode formed on the surface of the device, that is, the thickness of the plating is uniform not only in the semiconductor device but also in the semiconductor substrate.

  In order to make the plating thickness uniform within the substrate, it is necessary to keep the ion concentration of the plating metal in the vicinity of the substrate to be plated at a predetermined concentration. For this reason, a method of constantly replacing the plating solution around the substrate by stirring the plating solution or applying a predetermined flow rate to the plating solution is used.

  In such an electroplating method, as a method for keeping the plating thickness uniform in the substrate, for example, in Patent Document 1, a substrate is inserted by inserting a shielding plate having an opening between the substrate and the anode electrode. The plating thickness in the inside is made uniform. The size and / or shape of the opening of the shielding plate is variable. For example, in Patent Document 1, by controlling the shape of the opening of the shielding plate, the electric field on the surface of the substrate is controlled, and the plating thickness in the semiconductor substrate is kept uniform.

  FIG. 4 is a plan view showing an example of the shielding plate disclosed in Patent Document 1. As shown to Fig.4 (a), the magnitude | size of an opening part is changed by using several shield plates from which the opening part 7a differs, and inserting / removing it. As shown in FIG. 4B, the size of the opening 17a provided in the center of the shielding plate 17 can be arbitrarily changed by a mechanism similar to that of the lens diaphragm.

Patent Document 2 discloses a method of measuring a natural electrode potential using a SCE (saturated gypsum electrode) as a standard electrode before plating and controlling the plating voltage in accordance with a change with time of the potential. .
JP 11-246999 A (published September 14, 1999) Japanese Patent Laid-Open No. 2-190492 (released July 26, 1990)

  However, the above-described conventional technique has the following problems.

  First, in the technique disclosed in Patent Document 1, in order to keep the potential distribution in the plating tank uniform, the positional relationship of the plating solution flow, the distance from the substrate, and the position from the shielding plate are only set in hardware. There was no other way than electroplating in a state set under ideal conditions. That is, in Patent Document 1, the electric field on the surface of the substrate is controlled by a structural setting that controls the shape of the opening of the shielding plate, resulting in variations in the parallelism of the substrate, the flow of the plating solution, or the applied voltage. Performs electroplating under ideal conditions with no problems.

  Therefore, when mass-produced plating substrates using a plating device, it is possible to detect slight changes in parameters that deteriorate the uniformity of plating thickness, such as substrate parallelism, plating solution flow, and applied voltage variations. Can not. And production was continued as it was, and there was a case where a defect was noticed only at the final stage of shipping inspection.

  The technique described in Patent Document 2 is a measurement before plating. For this reason, this method does not monitor changes in potential during plating and cannot cope with changes in the equipment state after the start of production. In addition, a method for monitoring the potential during the plating process and applying feedback has been conventionally studied. However, since the potential during the plating process is not stable, it has not been put into practical use.

  The present invention has been made in view of the above problems, and its purpose is to provide a plating apparatus that can monitor the potential during the plating process and can prevent uneven plating thickness of the substrate to be plated, A plating processing management device, a plating method, and a plating processing management method are provided.

In order to solve the above-described problems, the plating apparatus of the present invention includes a plating tank filled with a plating solution, the substrate to be plated is a cathode electrode, and the substrate to be plated and the anode electrode are opposed to each other substantially in parallel. is immersed in the liquid, an apparatus for performing electrolytic plating on the substrate to be plated, and the potential measuring device for measuring the potential of the two points from the substrate to be plated ing equidistant, two points measured by the potential measuring instrument And comparing means for determining the difference or ratio of the potentials, and monitoring whether or not the potential at the two points fluctuates while maintaining a constant difference or ratio based on the difference or ratio determined by the comparing means. It is characterized by having monitoring means.

  The potential in the plating solution varies depending on the apparatus configuration such as the applied voltage, the relative position between the substrate to be plated and the anode electrode, the flow rate of the plating solution, or the concentration of the metal to be plated.

  For this reason, when a potential change at one location in the plating solution is monitored during the plating process, it is determined whether the voltage change indicates a change according to the device configuration in the plating solution or a change due to a voltage abnormality. It was difficult. Therefore, it is difficult to determine whether the voltage abnormality in the plating solution is good or bad.

  However, according to the above configuration, the monitoring unit monitors the balance of potential change between at least two points that are equidistant from the substrate to be plated. “Balance of potential change” refers to a state in which the potential of at least two points in the plating solution fluctuates while maintaining a certain difference or ratio.

In general, the potential in the plating solution is not constant, and the ratio of the resistance between the electric double layer and the plating solution is affected. Therefore, the monitoring means is based on the potential ratio between at least two points in the plating solution. Rather than monitoring the balance of changes in potential, it is preferable to monitor the balance of changes in potential based on the difference in potential between two points in the plating solution.

According to the above configuration, when the balance of the potential change is maintained between the two potentials, it can be determined that the variation according to the device configuration in the plating solution is exhibited, while the balance of the potential change is achieved. Can be determined to indicate a change due to voltage abnormality. This makes it possible to determine whether the voltage abnormality in the plating solution is good or bad. Therefore, according to the above configuration, the potential during the plating process can be monitored, and non-uniformity of the plating thickness of the substrate to be plated can be prevented.

  Furthermore, according to the above configuration, by monitoring the balance of potential changes in the plating solution, in the electrolytic plating process, the parallelism between the anode electrode and the substrate to be plated is disturbed, current application troubles, the flow of the plating solution. It is possible to detect abnormalities in real time, prevent uneven plating thickness (bump electrode height), reduce the defect rate in the plating process, and widen the mounting margin in the second half process. It becomes.

  The positional relationship of “at least two points” at which the monitoring means monitors the balance of changes in potential is not particularly limited as long as the positional relationship is theoretically the same potential between the two points. “At least two points” that ensure the same potential are positions that are equidistant from the substrate to be plated. In general, since the potential fluctuates during the plating process, the position where the potential does not change theoretically between two points even when the potential changes is equidistant between the substrate to be plated and the anode electrode. It becomes a position like this.

Further, in the plating apparatus of the present invention, the monitoring means preferably further comprises a comparing means for comparing the potential of the upper Symbol 2 points.

  Note that “compare potentials between at least two points” means obtaining a difference or ratio of potentials between at least two points.

According to the above configuration, the comparison means, so to compare the potential between the upper Symbol two points, from the comparison result, at least between two points, it can be determined whether the balance of the change in the potential is maintained.

In the plating apparatus of the present invention, it is preferable that the monitoring unit further includes a reporting unit that reports when the potential difference between the two points becomes a predetermined level or more.

According to the above configuration, since the reporting means reports when the difference between the potentials at the two points exceeds a predetermined level, the user can recognize the voltage abnormality in the plating solution.

In the plating apparatus of the present invention, it is preferable that the monitoring unit further includes an interlock mechanism that stops the electrolytic plating when the difference between the potentials at the two points exceeds a predetermined level.

According to the above configuration, the interlock mechanism stops the electroplating when the difference between the potentials at the two points exceeds a predetermined level. Therefore, when the voltage abnormality in the plating solution occurs, the plating process is performed. Without proceeding, it is possible to prevent uneven plating thickness of the substrate to be plated and to reduce the defective rate of the plating process.

Further, in the plating apparatus of the present invention, the level of the difference in potential between two points alarm means you alarm is dependent on the uniformity of the specification of the plating thickness of the substrate to be plated can be set appropriately . In particular, by using the semiconductor substrate as a substrate to be plated, on its semiconductor substrate, when performing electrolytic plating to form the bump electrodes, said alarm means, for the potential of the upper Symbol 2 points, the difference in potential is the It is preferable to report when the potential becomes 10% or more of the lowest potential of the two potentials.

  There is a correlation between the plating film thickness and the potential in the plating solution. Generally, the variation of the plating film thickness is about 15 to 20% in mass production, and a value larger than this is insufficient as an interlock mechanism. The reason why the minimum potential is set to 10% or more of the potentials of at least two points is that, in the detection of the potential in the plating solution, the amplitude is as large as 10% and the detection accuracy is ± 10 mV. .

  The reporting condition by the reporting means is obtained from the actual value of the amplitude of the potential and the height specification of the mass production (variation of plating film thickness in mass production), and is appropriately determined according to the configuration of the electroplating apparatus. Can be set. For example, when the specification of height variation (plating film thickness variation in mass production) is 10% or less, the reporting means is 5% or less of the smallest potential of at least two points of potential. Will start to report.

In the plating apparatus of the present invention, the potential measuring device preferably includes two potential monitor terminals for detecting a potential in the plating solution.

According to the above configuration, the potential measuring device detects the potential at two points in the plating solution by using at least two potential monitor terminals, and monitors the balance of potential changes in the plating solution. As a result, in the electrolytic plating process, it becomes possible to detect in real time the disturbance of parallelism between the anode electrode and the substrate to be plated, the trouble of current application, and the abnormal flow of the plating solution. It is possible to prevent unevenness in height), reduce the defect rate in the plating process, and widen the mounting margin in the second half process.

  In the plating apparatus of the present invention, in particular, when a semiconductor substrate is used as a substrate to be plated and electrolytic plating is performed to form bump electrodes on the semiconductor substrate, the distance between the substrate to be plated and the potential monitor terminal is determined. Is preferably 0.1 mm or more.

  The resistance of the plating solution is determined by the conductivity of the plating solution and the electric double layer appearing on the surface of the substrate to be plated (the resistance of the plating solution <the electric double layer). Here, the electric double layer has a very small thickness of 0.1 mm or less and is on the order of several μm. For this reason, the potential monitor terminal needs to be positioned outside the electric double layer, and the distance from the substrate to be plated is 0.1 mm or more. This makes it possible to reliably insulate from the electric double layer. If the distance between the substrate to be plated and the potential monitor terminal is smaller than 0.1 mm, the electric double layer appearing on the surface of the substrate to be plated and the potential monitor terminal may be in contact with each other. This is not preferable because it inhibits the growth of plating on the surface of the substrate to be plated.

  From the above description, “the distance between the substrate to be plated and the potential monitor terminal is 0.1 mm or more” means that the potential monitor terminal is located 0.1 mm or more of the position of the electric double layer. It can be said.

  Moreover, in the plating apparatus of this invention, it is preferable that the said electric potential monitor terminal is comprised with the gold wire or the platinum wire.

According to the above configuration, since the potential monitor terminal is composed of a gold wire or a platinum wire, for example, as compared with the case where a base metal such as copper (Cu) or nickel (Ni) is used as the potential monitor terminal, Even if the metal is dissolved in the plating solution, it is not oxidized and the state of the plating solution does not change. Therefore, according to the above configuration, Ru can determine the acceptability of better voltage in the plating liquid abnormal.

Also, in the plating apparatus of the present invention further includes a stirring means for stirring the plating solution, said monitoring means monitors the potential of the large period, upper Symbol 2 points than stirred cycle by the stirring means, and the average value of the monitored potential in the period, it is preferable to monitor whether or not the potential of the upper Symbol two points varies while keeping a constant difference or ratio.

In the plating apparatus provided with a stirring means, the potential at an arbitrary position of the plating solution, so varies the agitation operation, the monitoring means, the two potentials, can not be read in a stable value. However, according to the above configuration, the monitoring means is greater period of time than stirring cycle by stirring means, monitors the potential of the upper Symbol 2 points, an average value of the monitored potential in the period, the Since it is monitored whether or not the potentials at the two points fluctuate while maintaining a constant difference or ratio, the potential fluctuation factors due to the stirring operation described above can be canceled, and the monitoring means stabilizes the potential in the plating solution. Can be read as a value.

  When stirring is performed by the stirring means, the potential of the plating solution varies depending on the positional relationship from the stirring means. That is, the potential in the plating solution varies depending on the flow of the plating solution. In order to exclude the influence of stirring by such stirring means, the potential at any point in the plating solution does not fluctuate in the same tendency by averaging the potential over a wider range than the stirring cycle. Even in this case, it is possible to determine the plating thickness.

In order to solve the above problems, the plating processing management apparatus of the present invention uses a substrate to be plated as a cathode electrode, immerses the substrate to be plated and the anode electrode in a plating solution so as to face each other substantially parallel, a plating management apparatus for managing a plating process to electroplating plating substrate, and the potential measuring device for measuring the potential of the two points from the substrate to be plated ing equidistant, two points measured by the potential measuring instrument And comparing means for determining the difference or ratio of the potentials, and monitoring whether or not the potential at the two points fluctuates while maintaining a constant difference or ratio based on the difference or ratio determined by the comparing means. It is characterized by having monitoring means.

According to the above configuration, the monitoring means, since monitors the balance of potential changes between two points from the substrate to be plated ing equidistant from the balance shows a change corresponding to the device configuration in the plating solution Or whether a change due to a voltage abnormality is indicated. Therefore, it is possible to determine whether the voltage abnormality in the plating solution is good or bad.

  Therefore, according to the above configuration, it is possible to provide a plating process management apparatus that can monitor the potential during the plating process and can prevent the unevenness of the plating thickness of the substrate to be plated.

In order to solve the above problems, the plating method of the present invention uses a substrate to be plated as a cathode electrode, immerses the substrate to be plated and the anode electrode in a plating solution so as to face each other substantially in parallel, to a plating method for performing electrolytic plating, to measure the potential of the two points ing equidistant from the substrate to be plated, it obtains the difference or ratio of the potential of the measured two points, based on the difference or ratio determined And a monitoring step of monitoring whether or not the potentials at the two points fluctuate while maintaining a constant difference or ratio.

According to the above configuration, in the monitoring process, between the two points from the substrate to be plated ing equidistant, since monitoring the balance of the change of the potential, the balance of the voltage change, the device configuration in the plating solution It is possible to determine whether the corresponding change is indicated or whether the change is due to voltage abnormality. Therefore, it is possible to determine whether the voltage abnormality in the plating solution is good or bad.

In order to solve the above problems, the plating treatment management method of the present invention uses a substrate to be plated as a cathode electrode, immerses the substrate to be plated and the anode electrode in a plating solution so as to face each other substantially parallel, a plating management method for managing a plating process to electroplating plating substrate, and measuring the potential of the two points from the substrate to be plated ing equidistant calculates a difference or ratio of the potential of the measured two points, It is characterized by including a monitoring step of monitoring whether or not the potentials at two points change while maintaining a constant difference or ratio based on the obtained difference or ratio .

  According to the above configuration, it is determined whether a change corresponding to the device configuration in the plating solution or a change due to voltage abnormality is shown based on a balance of voltage changes between at least two points that are equidistant from the substrate to be plated. It becomes possible. Therefore, it is possible to determine whether the voltage abnormality in the plating solution is good or bad.

Further, in the plating process management method of the present invention further comprises a stirring step for stirring the plating solution at the monitoring step, greater periods of time than stirring period in the stirring step, the monitoring of the potential of the upper Symbol 2 points Preferably, the potential monitored during the period is averaged.

Plating apparatus of the present invention, as described above, the potential measuring device for measuring the potential of the two points ing equidistant from the substrate to be plated, the difference or ratio of the potentials of two points measured by the potential measuring instrument And a monitoring means for monitoring whether or not the potentials at two points fluctuate while maintaining a constant difference or ratio based on the difference or ratio obtained by the comparison means. is there. The plating process managing device of the invention, as described above, the potential measuring device for measuring the potential of the two points ing equidistant from the substrate to be plated, the difference between the potential of the two points measured by the potential measuring instrument Or a comparison means for obtaining a ratio, and a monitoring means for monitoring whether or not the potential at two points fluctuates while maintaining a constant difference or ratio based on the difference or ratio obtained by the comparison means. It is a configuration.

Further, the plating method of the present invention, as described above, by measuring the potential of the two points from the substrate to be plated ing equidistant calculates a difference or ratio of the potential of the measured two-point was determined difference or This is a configuration including a monitoring step for monitoring whether or not the potentials at two points fluctuate while maintaining a constant difference or ratio based on the ratio . The plating process management method of the present invention, as described above, by measuring the potential of the two points from the substrate to be plated ing equidistant calculates a difference or ratio of the potential of the measured two points, the determined difference Or it is the structure including the monitoring process which monitors whether the electric potential of two points changes, maintaining a fixed difference or ratio based on a ratio .

  Thereby, the potential during the plating process can be monitored, and non-uniformity of the plating thickness of the substrate to be plated can be prevented. In addition, by monitoring the balance of potential changes in the plating solution, it is possible to detect in real time in the electrolytic plating process the disorder of parallelism between the anode electrode and the substrate to be plated, current application troubles, and abnormalities in the plating solution flow. This makes it possible to prevent uneven plating thickness (bump electrode height), reduce the defect rate in the plating process, and widen the mounting margin in the latter half of the process.

  An embodiment of the present invention will be described below with reference to FIGS.

  A schematic configuration of the electrolytic plating apparatus of the present embodiment is shown in FIG. In the electrolytic plating apparatus 10, the plating bath 3 is filled with the plating solution 3. The plating solution 3 is circulated by the stirring unit 9 and a pump (not shown).

  In the plating solution 3, a substrate 4 to be plated and a positive electrode (anode) 5 which are cathode electrodes (canodes) are arranged facing each other. A DC voltage is applied to the substrate 4 and the anode electrode 5 by the power source 1. In the electrolytic plating apparatus 10, the power source 1 applies a predetermined DC voltage to the substrate to be plated 4 and the anode electrode 5, thereby depositing a plating metal at a predetermined position on the substrate to be plated 4.

  A shielding plate 7 is disposed between the substrate to be plated 4 and the anode electrode 5. The shielding plate 7 serves as a control plate that controls the electric field distribution in the plating solution 3. Thereby, the uniformity of the plating thickness of the to-be-plated substrate 4 can be improved. In this embodiment, as the shielding plate 7, as described in Japanese Patent Application Laid-Open No. 2003-34893, a plate drawn out in a circle slightly smaller than the substrate 4 to be plated is used. However, the shielding plate 7 is not limited to this configuration, and may be any configuration that can control the electric field distribution in the plating 3.

  In addition to these, the electrolytic plating apparatus 10 is accompanied by many other components such as an inlet and an outlet of the plating solution 3 to the plating tank 2, but in order to avoid the complexity of the drawing. In the drawings, the description of the configuration not particularly related to the characteristic points of the present invention is omitted.

  In the present embodiment, two potential monitor terminals, potential monitor terminals 6 a and 6 b, are inserted into the plating solution 3 in the electrolytic plating apparatus 10. Then, the potentials Va and Vb of the potential monitor terminals 6a and 6b are measured.

  The two potential monitor terminals 6 a and 6 b are disposed in the vicinity of the substrate 4 to be plated and are located at a distance from the substrate 4 to be plated. For example, the potential monitor terminals 6a and 6b are installed so that the distance between these detection units and the substrate 4 to be plated is about 5 mm. However, the distance between the potential monitor terminals 6a and 6b and the substrate 4 to be plated is not limited to 5 mm, and may be in the range of about 0.2 mm to 20 mm. In FIG. 1, the potential monitor terminals 6a and 6b are disposed at different distances from the substrate 4 to be plated, but originally the potential monitor terminals 6a and 6b are disposed so as to overlap with the paper surface in the vertical direction. Has been. In FIG. 1, the positions are shifted for convenience.

  In the electroplating apparatus 10, the monitoring unit 8 monitors the balance of changes in the potentials Va and Vb of the potentials Va and Vb measured from the potential monitor terminals 6a and 6b. Hereinafter, the configuration of the monitoring unit 8 will be described with reference to FIG. FIG. 2 is a block diagram showing a schematic configuration of the monitoring unit 8 in the electrolytic plating apparatus 10 of the present embodiment.

  As shown in FIG. 2, the monitoring unit 8 includes potential measuring devices 20a and 20b, a comparing unit (comparing unit) 11, a determining unit 12, a reporting unit 13 (reporting unit), an interlock mechanism 14, An average value calculation unit 15 and an agitation control unit 16 are provided.

  The potential measuring devices 20a and 20b measure the potentials Va and Vb. Then, the outputs of the potential measuring devices 20 a and 20 b are input to the comparison unit 11.

  The comparison unit 11 compares the potential Va detected at the potential monitor terminal 6a with the potential Vb detected at the potential monitor terminal 6b. That is, the comparison unit 11 obtains the difference or ratio between the potential Va and the potential Vb.

  In the plating apparatus provided with the stirring unit 9, the stirring control unit 16 controls the stirring operation by the stirring unit 9. Specifically, the stirring cycle of the stirring operation is controlled. Then, the stirring control unit 16 passes time information of the stirring cycle in this stirring operation to the average value calculating unit 15. Based on the time information from the stirring control unit 15, the average value calculation unit 15 calculates an average value for the potentials Va and Vb detected during a period longer than the stirring cycle. Since the potential at any position in the plating solution varies depending on the stirring operation by the stirring unit 9, stable values may not be obtained as the potentials Va and Vb detected from the potential monitor terminals 6a and 6b. The average value calculation unit 15 calculates the average value for each of the potentials Va and Vb detected during a period longer than the stirring cycle by the stirring unit 9 in order to cancel the potential fluctuation factor due to the stirring operation of the stirring unit 9. Calculated. Then, the average value obtained by the average value calculation unit 15 is compared by the comparison unit 11.

  Then, based on the difference or ratio between the potential Va and the potential Vb obtained by the comparison unit 11, the determination unit 12 determines whether or not the balance of the potential change is maintained between the potential Va and the potential Vb. Determine whether.

  When the determination unit 12 determines that the balance of potential change is not maintained between the potential Va and the potential Vb, that is, the difference or ratio between the potential Va and the potential Vb becomes equal to or higher than a predetermined level. If it is determined that there is, the reporting unit reports a potential abnormality in the plating solution, and the interlock mechanism 14 stops the electrolytic plating of the electrolytic plating apparatus. Thereby, the user of the plating apparatus can recognize the voltage abnormality in the plating solution.

  Further, since the interlock mechanism 14 stops the electrolytic plating operation of the electrolytic plating apparatus, it is possible to prevent the plating process from proceeding when a voltage abnormality in the plating solution occurs.

  As described above, the monitoring unit monitors the balance of potential changes between the potential Va and the potential Vb, so that the potential during the plating process can be monitored, and the plating thickness of the substrate to be plated is not uniform. Can be prevented.

  Below, the determination method of the voltage abnormality in a plating solution based on the comparison with the electric potential Va and the electric potential Vb by the comparison part 11 is demonstrated based on FIG. FIG. 5 is a graph showing a potential waveform in the plating solution 3 in the electrolytic plating apparatus 10, and FIG. 5A shows the voltage V0 applied by the power source 1 and the voltage Va measured at the potential monitor terminal 6a. FIG. 5B shows the voltage waveform of the potential Va measured at the potential monitor terminal 6a and the potential Vb measured at the potential monitor terminal 6b.

  First, in the electrolytic plating apparatus 10, the potential in the plating solution 3 is determined by the applied voltage of the power source 1, the relative position between the substrate 4 to be plated 4 and the anode electrode 5, the plating solution flow rate, or the metal to be plated. Varies depending on the concentration. As shown in FIG. 5A, when the applied voltage V0 from the power source 1 is compared with Va measured at the potential monitor terminal 6a, the applied voltage V0 is substantially constant while the potential Va is constant. It keeps changing while maintaining the amplitude of. That is, it can be seen that in the electrolytic plating apparatus 10, the potential in the plating solution 3 changes at a constant cycle.

  Therefore, when there is only one terminal for monitoring the potential of the plating solution during the plating process, that is, when the voltage is measured only at one point in the plating solution, the voltage change is a periodic change of the voltage in the plating solution. It is difficult to determine whether or not it indicates a change due to voltage abnormality. Therefore, it is difficult to determine the quality of the voltage abnormality in the plating solution.

  On the other hand, in the electrolytic plating apparatus 10, there are two terminals, potential monitor terminals 6a and 6b, as terminals for monitoring the potential of the plating solution during the plating process. The potential monitor terminals 6a and 6b are installed at positions where the measured potentials (Va, Vb) theoretically have the same potential.

  However, as described above, since the arbitrary potential in the plating solution varies depending on various factors such as the concentration of metal ions, the potential Va and the potential Vb are not completely the same and show slightly different values. For this reason, even if the potential is theoretically the same, different potentials are measured at two points in the plating solution during the plating process.

  Further, there are equipotential contour lines in places where the distance between the anode (anode electrode) and the cathode (substrate to be plated) is different and the ratio of the distance is the same. However, in reality, the contour lines change from time to time due to microscopic variations in the plating solution flow and the gold concentration of the plating solution, so theoretically it cannot be said to be equipotential. In the present invention, paying attention to this point, monitor terminals are usually installed at two places where exactly the same potential is shown. Then, by determining the difference in potential between the two points, an anomaly that is contrary to theory is to be detected.

  When the potential Va and the potential Vb are compared, it can be seen that the potential Va and the potential Vb fluctuate while maintaining a predetermined difference from each other, as shown in FIG. 5B. Therefore, the comparison unit 11 compares the potential Va and the potential Vb, and reads the difference between the potential Va and the potential Vb, so that it is possible to determine whether the voltage abnormality in the plating solution is good or bad. That is, when the potential Va and the potential Vb fluctuate without maintaining the predetermined difference, it can be determined that the voltage in the plating solution is abnormal.

  In the electrolytic plating apparatus 10, the potentials Va and Vb taken out from the potential monitor terminals 6a and 6b are respectively calculated as average values for a predetermined time. Then, the comparison unit 11 compares the difference between the potential Va and the potential Vb. Usually, in an electroplating apparatus, forced stirring using a stirring rod (stirring means) is used in combination with circulation of the plating solution. Therefore, the potential at an arbitrary position of the plating solution varies depending on the stirring operation. Therefore, stable values cannot be obtained as the potentials Va and Vb.

  Therefore, in the present embodiment, the potentials Va and Vb are monitored for a time that is twice or more the stirring cycle in order to cancel such a variation factor due to stirring. A stable value could be obtained by comparing the average values of the monitored potentials Va and Vb.

  Hereinafter, a case where the applied voltage V0 is 400 mV will be described. In this case, the potential in the plating solution 3 in the electrolytic plating apparatus 10 was 200 mV to 250 mV. That is, as shown in FIG. 5B, the potential Va and the potential Vb both have an amplitude centering on 200 mV. Therefore, for example, even if the average value of the voltage Va is 200 mV, the voltage value has a variation of 10 mV or more, and may vary greatly in particular. is there. In FIG. 5B, the potential Va and the potential Vb are displayed with the 0V (reference) line shifted.

  However, the applied voltage V0 is merely an example, and can be appropriately set according to the design such as the dimensions of the electrolytic plating apparatus or the substrate to be plated and the plating thickness. Further, the potential in the plating solution also changes in accordance with the set applied voltage, the dimensions of the electrolytic plating apparatus or the substrate to be plated, and the plating thickness.

  In addition, the potentials Va and Vb are monitored and averaged for 10 times the stirring cycle, thereby providing measurement accuracy. In the electrolytic plating apparatus 10, when the potential difference between the potential Va and the potential Vb becomes about 10% of the potential in the plating solution 3 (when the potential Va and the potential Vb have a difference of 20 mV or more), Judge that there is an abnormality in the voltage in the plating solution. In addition, the standard of the voltage value for judging the voltage abnormality in the plating solution depends on the specification of the uniformity of the height of the electrode formed by the plating process, and can be arbitrarily set according to the specification. It is.

  Here, the “uniformity specification” specifically refers to a variation of about 15 to 20% of the plating film thickness in mass production of the plated substrate.

  Further, in the electrolytic plating apparatus 10, when the potential difference between the potential Va and the potential Vb is about 10% (20 mV) of the potential in the plating solution 3, and it is determined that there is an abnormality in the plating apparatus, the abnormality is detected. It is equipped with an alarm (reporting means) as a reporting unit for reporting. And it has the interlock mechanism which stops an electrolytic plating process by the alerting | reporting of this alarm.

  That is, as shown in FIG. 1, the comparison unit 11 controls to stop the voltage application of the power supply 1 via the interlock mechanism. Thereby, an interlock function is realized.

  The present invention also includes a plating processing management device provided with potential monitor terminals 6a and 6b, a monitoring unit 8, an alarm, and an interlock mechanism. Thereby, the potential in the plating solution in the plating apparatus can be constantly monitored. In addition, by monitoring the balance of potential changes in the plating solution, it is possible to manage in real time the disturbance of parallelism between the anode electrode and the substrate to be plated, current application troubles, and abnormalities in the plating solution flow in the electrolytic plating process. . Therefore, nonuniform plating thickness (bump electrode height) can be prevented, the defect rate in the plating process can be reduced, and the mounting margin in the latter half process can be increased.

  In the present embodiment, noble metal having the same component as the metal to be plated is used as the potential monitor terminals 6a and 6b. More specifically, a potential monitor terminal in which a gold wire or a platinum wire having a diameter of about 0.5 mm to 5 mm is coated with a thin insulator that is not violated by the plating solution, and gold or platinum is exposed only at the tip. . Note that gold or platinum in the potential monitor terminal may be processed into a plate shape.

  When a base metal such as Cu (copper) such as nichrome wire or Ni (nickel) is used as the potential monitor terminals 6a and 6b, the metal used for the potential monitor terminal is dissolved into the plating solution. For this reason, since the state of a plating solution changes, it is not preferable. Therefore, it is preferable to use a metal that is not oxidized and does not affect the plating solution even if it is dissolved in the potential monitor terminals 6a and 6b.

  Further, as the potential monitor terminals 6a and 6b, glass electrodes such as a saturated gypsum electrode (SCE) that contacts the plating solution via glass may be used instead of the gold wire. When the SCE electrode is used, since the size of the terminal becomes larger than when the gold wires are used as the potential monitor terminals 6a and 6b, it is embedded in the plating tank or the holder of the substrate so as not to hinder the flow of the plating solution. Etc. are necessary.

  Moreover, the plating apparatus of the present invention uses a substrate to be plated as a cathode electrode, immerses in a plating solution filled in a plating tank with the substrate to be plated and the anode electrode facing each other substantially in parallel, and performs plating by an electrolytic plating method. It can be said that the apparatus for plating the substrate has a configuration in which two or more potential monitor terminals for monitoring the potential are provided in the plating tank.

  In this case, the plating apparatus of the present invention constantly monitors the potential at two or more potential monitor terminals, and issues an alarm when the difference between the two or more potentials exceeds a predetermined level. An interlock function is provided to stop the plating process. In particular, it is preferable that the interlock function works when the potential difference between the potential monitor terminals is 10% or more.

  According to this configuration, in the electrolytic plating process, terminals for monitoring the potential in the liquid are provided at two or more locations in the plating treatment tank, and the comparator for comparing the potential in the plating treatment tank is used. When it reaches, an alarm is issued and the electroplating process is stopped, thereby making it possible to prevent plating thickness variations in the wafer (surface to be plated).

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

  As described above, the plating apparatus of the present invention can monitor the potential during the plating process and can prevent the unevenness of the plating thickness of the substrate to be plated. Therefore, the present invention can be applied to industries that require plating, for example, the semiconductor industry.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an embodiment of the present invention and is an explanatory diagram illustrating a schematic configuration of an electrolytic plating apparatus. It is a block diagram which shows schematic structure of the monitoring part of the said electroplating apparatus. Sectional drawing which shows the process flow of formation of a bump electrode is shown, (a) shows the structure of the semiconductor substrate before forming a bump electrode, (b)-(e) is on the semiconductor substrate shown to (a) Shows the process until the bump electrode is formed. It is a top view which shows the structure of the shielding board used with the conventional electroplating apparatus, (a) shows the structure of the shielding board which changes the magnitude | size of an opening using several shielding boards from which the aperture diameter differs. (B) shows the structure of the shielding board which can change arbitrarily the magnitude | size of the opening provided in the center by the mechanism similar to the aperture_diaphragm | restriction of a lens. It is a photograph which shows the electric potential waveform in the plating solution 3 in the electrolytic plating apparatus 10, (a) shows the voltage waveform of Va applied voltage V0 by the power supply 1, and the potential monitor terminal 6a, (b). Indicates the voltage waveform of Va measured at the potential monitor terminal 6a and the voltage waveform of Vb measured at the potential monitor terminal 6b.

DESCRIPTION OF SYMBOLS 1 Power supply 2 Plating tank 3 Plating solution 4 Substrate to be plated 5 Anode electrode 6a Potential monitor terminal 6b Potential monitor terminal 7 Shielding plate 8 Monitoring unit (monitoring means)
9 Stirring section (stirring means)
10 Electrolytic plating equipment (plating equipment)
11 Comparison part (comparison means)
12 Judgment part 13 Reporting part (reporting means)
14 Interlock mechanism 15 Average value calculator

Claims (12)

An apparatus that includes a plating tank filled with a plating solution, uses the substrate to be plated as a cathode electrode, and immerses the substrate to be plated and the anode electrode in a plating solution so as to face each other substantially in parallel, and performs electrolytic plating on the substrate to be plated. There,
It comprises a potential measurement device for measuring the potential of the two points from the substrate to be plated ing equidistant, and a comparison means for obtaining a difference or ratio of the potentials of two points measured by the potential measuring instrument, by the comparing means A plating apparatus comprising: monitoring means for monitoring whether or not the potential at two points changes while maintaining a constant difference or ratio based on the obtained difference or ratio . The plating apparatus according to claim 1, wherein the monitoring unit further includes a reporting unit that reports when a difference between potentials at two points becomes a predetermined level or more. The plating apparatus according to claim 1, wherein the monitoring unit further includes an interlock mechanism that stops electroplating when a difference between potentials at two points becomes a predetermined level or more. The reporting means is configured to report the potential at the two points when the potential difference becomes 10% or more of the smallest potential among the potentials at the two points. Item 3. The plating apparatus according to Item 2 . The plating apparatus according to any one of claims 1 to 4, wherein the potential measuring device includes two potential monitor terminals for detecting a potential in the plating solution. 6. The plating apparatus according to claim 5, wherein a distance between the substrate to be plated and the potential monitor terminal is 0.1 mm or more. The plating apparatus according to claim 5 or 6, wherein the potential monitor terminal is constituted by a gold wire or a platinum wire. Furthermore, a stirring means for stirring the plating solution is provided,
The monitoring means monitors the potential at the two points during a period longer than the stirring cycle by the stirring means, obtains an average value of the potentials monitored during the period, and the potential at the two points is a constant difference. Or it is monitored whether it changes, maintaining a ratio, The plating apparatus of any one of Claims 1-7 characterized by the above-mentioned. A plating processing management apparatus for managing a plating process in which a substrate to be plated is a cathode electrode, and the substrate to be plated and the anode electrode are opposed to each other in a substantially parallel manner and immersed in a plating solution, and electrolytically plated on the substrate to be plated.
A potential measuring device that measures the potential at two points that are equidistant from the substrate to be plated and a comparison means that obtains a difference or ratio between the potentials of the two points measured by the potential measuring device. A plating process management apparatus, comprising: monitoring means for monitoring whether or not the potentials at two points fluctuate while maintaining a constant difference or ratio based on the difference or ratio. A plating method in which the substrate to be plated is a cathode electrode, the substrate to be plated and the anode electrode are opposed to each other substantially in parallel and immersed in a plating solution, and electrolytic plating is performed on the substrate to be plated,
Measure the potential of two points that are equidistant from the substrate to be plated, determine the difference or ratio of the measured potentials of the two points, and based on the calculated difference or ratio, the difference or ratio of the two points is constant A plating method characterized by including a monitoring step of monitoring whether or not the fluctuation occurs while maintaining the temperature. A plating process management method for managing a plating process in which a substrate to be plated is a cathode electrode, the substrate to be plated and the anode electrode are opposed to each other substantially in parallel and immersed in a plating solution, and electroplated on the substrate to be plated,
Measure the potential of two points that are equidistant from the substrate to be plated, determine the difference or ratio of the measured potentials of the two points, and based on the calculated difference or ratio, the difference or ratio of the two points is constant A plating process management method comprising a monitoring step of monitoring whether or not the fluctuation occurs while maintaining the temperature. Furthermore, it includes a stirring step for stirring the plating solution,
In the monitoring step, the potential of the two points is monitored for a period longer than the stirring cycle in the stirring step, and an average value of the potentials monitored in the period is obtained, and the potential of the two points is constant. The plating process management method according to claim 11, wherein whether or not the fluctuation is maintained while maintaining a difference or a ratio is monitored.