Patent Publication Number: US-2007102285-A1

Title: Apparatus for managing a plating liquid

Description:
TECHNICAL FIELD  
      The present invention relates to a method of measuring the concentration of a leveler in a plating liquid that is used by a plating apparatus for filling metal such as copper in interconnection trenches and holes defined in the surface of a semiconductor substrate or the like, and a method of and an apparatus for managing a plating liquid to manage the components thereof.  
     BACKGROUND ART  
      For filling interconnection trenches and holes defined in the surface of a semiconductor substrate or the like according to a copper sulfate electroplating process, it is often customary to add three organic additives, described below, to basic plating liquid components copper sulfate (CuSO4.5H2O), sulfuric acid (H2SO4), and chlorine (Cl) in order to improve the qualities of a plated film and increase the fillability (embeddability) of trenches and holes.  
      One of the three organic additives is a carrier (also referred to as a brightener) for making the plated film dense and for increasing the luster of the plated film. The carrier generally comprises a sulfuric compound (e.g., HS-CnH2n-SO3 Mercapto alkylsulfonic acid) and exists as an anion in a plating liquid. The carrier obstructs the deposition of copper ions and promotes the achievement of a finer structure of the plated film.  
      The second of the three organic additives is a polymer (also referred to as a suppressor or a carrier) for suppressing the deposition of adsorbed copper ions on the surface of a cathode thereby to increase activated polarization for increased uniform electrodeposition. The polymer generally comprises a surface-active agent such as PEG or PPG.  
      The third organic additive is a leveler comprising a nitrogen-containing compound such as polyamine or the like. The leveler is present as a cation in a plating liquid.  
      The leveler is adsorbed greatly in a region where the current density is high. In the region where the adsorption of the leveler is large, an activation overvoltage increases to suppress the deposition of copper. At the bottom of fine trenches and holes, however, the adsorption of the leveler is smaller, resulting in a larger amount of the deposition of copper. The deposited state with the raised bottom represents an excellent leveling capability.  
      The management of the concentration of additives in a plating liquid of copper sulfate is important in managing the qualities of a plated film and the embeddability of trenches and holes. However, no process is presently available for measuring the absolute concentration of a trace of organic compound in a strong acid.  
      The present general process of analyzing the concentration of additives in a plating liquid is called a CV (Cyclic Voltammetric) process or a CVS (Cyclic Voltammetric Stripping) process. According to this process, the amount of copper deposited on a rotating cathode electrode is measured and converted into the concentration of an additive referred to as a deposition inhibitor or promoter.  
      In a plating solution of copper sulfate, however, only the concentrations of the carrier and the polymer can be measured by the above process, and the concentration of the leveler cannot be measured by the above process. The concentration of the leveler is the smallest among the concentrations of the above three additives. The leveler has properties similar to those of the polymer, and it has been said that it is impossible to measure the concentration of the leveler even according to the CV or CVS process.  
      A method of managing and adjusting the components of a plating liquid used by a plating apparatus of the type described above will be described below. Consumed amounts of the components of a plating liquid are empirically determined when the plating apparatus starts to operate in a plating mode and also when the plating apparatus is operating in a steady mode. Depending on a quantity of electricity (current×time), an initial startup replenishing liquid (starter) is added to a base plating liquid. In a subsequent operation, a replenishing liquid (replenisher) is appropriately supplied to manage and adjust the components of the plating liquid. The starter comprises additive component liquids mixed depending on the consumed amounts of the components at the time of starting the plating apparatus. Similarly, the replenisher also comprises additive component liquids mixed depending on the consumed amounts of the components at the time of normal operation of the plating apparatus.  
      The empirical process has been used because it has been difficult to analyze the concentrations of the additives. However, since it is difficult to manage the concentrations accurately and the added amounts of the components are predetermined, this process finds it difficult to cope with a situation where the consumed amounts of the components are brought out of balance due to time-depending changes in the plating conditions.  
      There has recently been proposed an automatic analyzing device for quickly analyzing and automatically measuring additives according to an electrochemical process.  
     SUMMARY OF THE INVENTION  
      The present invention has been made in view of the above difficulties. It is an object of the present invention to provide a method of measuring the concentration of a leveler which is an additive in a plating liquid of copper sulfate, which has been impossible to measure according to a conventional CV or CVS process.  
      Another object of the present invention is to provide a method of and an apparatus for managing a plating liquid to automatically analyze additives of the plating liquid and adjust the components of the plating liquid based on the analyzed results.  
      In particular, a method of measuring the concentration of a leveler in a plating liquid of copper sulfate to measure the concentration of an additive containing nitrogen, which is referred to as a leveler, among organic additives contained in an electroplating liquid of copper sulfate is provided. The concentration of the leveler in the plating solution is determined based on a peak area (Ar value) in a peel-off region of the plating liquid measured according to a CV or CVS process.  
      Alternatively, a method of measuring the concentration of a leveler in a plating liquid of copper sulfate to measure the concentration of an additive containing nitrogen, which is referred to as a leveler, among organic additives contained in an electroplating liquid of copper sulfate is provided. The concentration of a brightener (carrier), and a wetting agent or a polarizing agent (polymer), which are other organic additives of the plating liquid, are analyzed. Thereafter, a calibration curve for the concentration of the leveler using a standard liquid prepared with the concentration of the carrier and the concentration of the polymer is generated. The concentration of the leveler of the plating liquid is determined based on a peak area (Ar value) in a peel-off region of the plating liquid measured according to a CV or CVS process.  
      As another alternative, a method of measuring the concentration of a leveler in a plating liquid of copper sulfate to measure the concentration of an additive containing nitrogen, which is referred to as a leveler, among organic additives contained in an electroplating liquid of copper sulfate is provided. A measuring liquid containing a promoting additive containing a sulfur-based material, which is referred to as a carrier, is prepared at a concentration that is 2 to 40 times a standard concentration. A difference in the amount of copper deposition on a rotary electrode according to a CV or CVS process is measured to calculate the concentration of the leveler.  
      The performance of the leveler in the plating solution of copper sulfate is not determined by the concentration of the leveler alone, but is affected by the concentrations of the carrier and the polymer. Particularly, the concentration of the carrier affects the leveling capability. If a nondye nitrogen compound such as polyamine or the like is used as the leveler, then the leveling nature becomes distinct, allowing a calibration curve to be drawn clearly, by increasing the concentration of the carrier in the plating liquid to be analyzed, relatively 2 to 40 times.  
      As another alternative, a method of measuring the concentration of a leveler in a plating liquid of copper sulfate to measure the concentration of an additive containing nitrogen, which is referred to as a leveler, among organic additives contained in an electroplating liquid of copper sulfate is provided. The plating liquid is passed through an organic anion-selective adsorption film to remove the promoting additive containing a sulfur-based material, which is referred to as a carrier, from the plating liquid. Thereafter, a difference in an amount of copper deposition on a rotary electrode is measured according to a CV or CVS process to calculate the concentration of the leveler.  
      If a nitrogen compound such as yanus green is used as the leveler, then the leveling nature becomes distinct, allowing a calibration curve to be drawn clearly, by bringing the amount of carrier closely to zero. Therefore, by passing the plating liquid through the organic anion-selective adsorption film, the carrier can be removed from the plating liquid, and a calibration curve can be drawn clearly.  
      Another method of managing a plating liquid includes sampling, at a predetermined interval, a predetermined amount of plating liquid in a plating apparatus which immerses a substrate to be plated in the plating liquid to plate a surface of the substrate. Components of the sampled plating liquid are analyzed with an automatic analyzing device, and component replenishing liquids comprising components of the plating liquid are supplied to the plating liquid based on analyzed results and/or the number of substrates to be plated and a quantity of electricity consumed to plate the substrates for thereby managing the components of the plating liquid. The component replenishing liquids comprise a standard liquid, a plurality of solutions of a basic liquid with a plurality of different additives added thereto, sulfuric acid, and hydrochloric acid, either wholly or partly, and the component replenishing liquids are supplied to the plating liquid for thereby individually replenishing and managing the components of the plating liquid.  
      In the above method, the basic liquid comprises a solution of at least copper sulfate (CuSO4.5H2O), and sulfuric acid (H2SO4), mixed at predetermined ratios. The standard liquid comprises a solution of the basic liquid, and the plurality of additives and hydrochloric acid added thereto at predetermined ratios.  
      A total amount of component replenishing liquids to be supplied to the plating liquid can be substantially the same as a reduction in the plating liquid which is caused by plating the substrate.  
      An apparatus is provided for managing the components of a plating liquid in a plating apparatus which immerses a substrate to be plated in the plating liquid in a plating tank to plate a surface of the substrates. The apparatus includes a plating liquid sampling device for sampling a predetermined amount of the plating liquid at a predetermined interval, an automatic analyzing device for automatically analyzing the components of the plating liquid sampled by the plating liquid sampling device, and a component replenishing liquid supply device for supplying component replenishing liquids comprising the components of the plating liquid. The component replenishing liquids are supplied to the plating liquid based on analyzed results from the automatic analyzing device and/or the number of substrates to be plated and a quantity of electricity consumed to plate the substrates for thereby managing the components of the plating liquid. The component replenishing liquids comprise a standard liquid, a plurality of solutions of a basic liquid with a plurality of different additives added thereto, sulfuric acid, and hydrochloric acid, either wholly or partly, and the component replenishing liquids are supplied by the component replenishing liquid supply device to the plating liquid for thereby individually replenishing and managing the components of the plating liquid.  
      In the above apparatus, the basic liquid comprises a solution of at least copper sulfate (CuSO4.5H2O), and sulfuric acid (H2SO4), mixed at predetermined ratios. The standard liquid comprises a solution of the basic liquid and the plurality of additives and hydrochloric acid added thereto at predetermined ratios.  
      The apparatus described above can include a plating liquid adjusting tank, separate from the plating tank, for supplying the component replenishing liquids to the plating liquid. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  is a diagram showing an arrangement of an apparatus for carrying out a method of measuring the concentration of a leveler in a plating liquid according to the present invention;  
       FIG. 2  is a diagram showing the relationship between the concentration of a leveler and the calibration curve for Ar values; and  
       FIG. 3  is a diagram showing an arrangement of a plating liquid managing apparatus for carrying out a method of managing the components of a plating liquid according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      An embodiment of the present invention will hereinafter be described with reference to the drawings.  FIG. 1  is a diagram showing an arrangement of an apparatus (automatic analyzing device) for carrying out a method of measuring the concentration of a leveler in a plating liquid of copper sulfate according to the present invention. In  FIG. 1 , the apparatus has a measurement cell  10  housing therein rotary disk electrodes  12  held by an electrode holder  11  and a stirring impeller  13  that can be driven in a contactless manner by a stirrer  14 . A potentiostat  15  for automatically adjusting currents to bring the potentials between the electrodes into a desired setting is connected to the electrode holder  11 .  
      A low-concentration basic liquid tank  21  holds a low-concentration basic liquid Q 1  therein. A high-concentration basic liquid tank  22  holds a high-concentration basic liquid Q 2  therein. A checking liquid tank  23  holds a checking liquid Q 3  therein. A first additive liquid tank  24  holds an additive A (polymer) liquid Q 4  therein. A second additive liquid tank  25  holds an additive B (carrier) liquid Q 5  therein. A third additive liquid tank  26  holds an additive C (leveler) liquid Q 6  therein. A standard liquid tank  27  holds a standard liquid Q 7  therein. The basic liquid comprises a solution of copper sulfate (CuSO4.5H2O), and sulfuric acid (H2SO4), mixed at predetermined ratios. The standard liquid comprises a solution of the basic liquid and a plurality of additives and hydrochloric acid that are added thereto at predetermined ratios. The checking liquid comprises a solution for checking the polymer, the solution containing the basic liquid and a certain amount of additive mixed therewith.  
      A burette  29  is connected to the low-concentration basic liquid tank  21  through a three-way valve  28  for extracting a certain amount of low-concentration basic liquid Q 1  from the low-concentration basic liquid tank  21  and supplying the extracted amount of low-concentration basic liquid Q 1  into the measurement cell  10 . Burettes  31 ,  33 ,  35 ,  37 ,  39 ,  41  are connected respectively to the high-concentration basic liquid tank  22 , the checking liquid tank  23 , the additive liquid tank  24 , the additive liquid tank  25 , the additive liquid tank  26 , and the standard liquid tank  27  through respective three-way valves  30 ,  32 ,  34 ,  36 ,  38 ,  40  for supplying certain amounts of high-concentration basic liquid Q 2 , checking liquid Q 3 , additive A liquid Q 4 , additive B liquid Q 5 , additive C liquid Q 6 , and standard liquid Q 7 , and for supplying the extracted amounts of high-concentration basic liquid Q 2 , checking liquid Q 3 , additive A liquid Q 4 , additive B liquid Q 5 , additive C liquid Q 6 , and standard liquid Q 7  into the measurement cell  10 .  
      A controller  42  comprising a CPU controls a driver  43  for switching the three-way valves  28 ,  30 ,  32 ,  34 ,  36 ,  38 ,  40  and activating and inactivating the burettes  29 ,  31 ,  33 ,  35 ,  37 ,  39 ,  41  depending on a polymer concentration measuring mode, a carrier concentration measuring mode, and a leveler concentration measuring mode, described below, and also controls various other parts.  
      A sample tank  44  holds a sample plating liquid whose concentration is to be measured. The sample plating liquid flows from a sample inlet port  45  into the sample tank  44 , overflows the sample tank  44 , and returns from a sample return port  46  to a plating apparatus (not shown). A sample nozzle  47  is positioned above the sample tank  44  and is connected to a burette  48  through a three-way valve  49 . The burette  48  extracts a certain amount of sample plating liquid from the sample tank  44  via the sample nozzle  47 . After the sample nozzle  47  is moved to a position over the measuring cell  10 , the burette  48  supplies the extracted sample plating liquid into the measuring cell  10 .  
      A pump  51  for delivering pure water is connected to the burette  48  and the sample nozzle  47  via the three-way valve  49  to wash them. The interior of the measurement cell  10  is also washed by pure water. The solution in the measurement cell  10  is drained by a pump  50 .  
      The polymer concentration measuring mode for measuring a polymer concentration, the carrier concentration measuring mode for measuring a carrier concentration, and the leveler concentration measuring mode for measuring a leveler concentration, which are carried out by the concentration measuring apparatus thus constructed, will be described below by way of example.  
      [Polymer Concentration Measuring Mode] 
      First, it is confirmed that the electrodes  12  are stable by extracting 50 ml of low-concentration basic liquid Q 1  from the low-concentration basic liquid tank  21 , supplying the extracted low-concentration basic liquid Q 1  to the measurement cell  10 , determining an Ar value, i.e., a peak area (time×current density=quantity of electricity) in a peel-off region according to the CVS process, and deciding whether the Ar value is an appropriate value or not. If the Ar value is not an appropriate value, the low-concentration basic liquid Q 1  is drained from the measurement cell  10 , the measurement cell  10  is washed, 50 ml of low-concentration basic liquid Q 1  is again extracted, the extracted low-concentration basic liquid Q 1  is supplied to the measurement cell  10 , and the above cycle is repeated.  
      If the Ar value is an appropriate value, then 1 ml of checking liquid Q 3  is extracted from the checking liquid tank  23  and supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process. The cycle of extracting and supplying the checking liquid Q 3  and measuring an Ar value according to the CVS process is repeated a predetermined number of times (usually five times, at most 10 times) to draw a calibration curve. When the calibration curve has been drawn, the liquid in the measurement cell  10  is drained, and the interior thereof is washed.  
      Then, 50 ml of low-concentration basic liquid Q 1  is extracted from the low-concentration basic liquid tank  21  and supplied to the measurement cell  10 , and it is decided whether an Ar value is an appropriate value or not (to confirm that the electrodes  12  are stable). If the Ar value is an appropriate value, then 1 ml of sample plating liquid (specimen) is extracted and added to the liquid in the measurement cell  10 , and an Ar value is measured according to the CVS process. The cycle of extracting and supplying the sample liquid and measuring an Ar value according to the CVS process is repeated a predetermined number of times (usually five times, at most 10 times) to draw a calibration curve. When the calibration curve has been drawn, the liquid in the measurement cell  10  is drained, and the interior thereof is washed.  
      A polymer concentration of the sample plating liquid is determined from a comparison between the above two calibration curves. Specifically, since the polymer concentration of the checking liquid Q 3  is known, the polymer concentration of the sample plating liquid can be determined by comparing the calibration curve obtained from the checking liquid Q 3  and the calibration curve of the sample plating liquid.  
      [Carrier Concentration Measuring Mode] 
      As with the above polymer concentration measuring mode, it is confirmed that the electrodes  12  are stable by extracting 50 ml of low-concentration basic liquid Q 1  from the low-concentration basic liquid tank  21 , supplying the extracted low-concentration basic liquid Q 1  to the measurement cell  10 , measuring an Ar value according to the CVS process, and confirming that the Ar value is an appropriate value.  
      If it is confirmed that the Ar value is an appropriate value, then the low-concentration basic liquid Q 1  is drained from the measurement cell  10  and the measurement cell  10  is washed. Thereafter, 48.5 ml of high-concentration basic liquid Q 2  is extracted from the high-concentration basic liquid tank  22 , 1 ml of additive A liquid Q 4  is extracted from the additive liquid tank  24 , and 0.5 ml of additive C liquid Q 6  is extracted from the additive liquid tank  26 . The extracted liquids are supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process. Then, 0.5 ml of additive B liquid Q 5  is extracted from the additive liquid tank  25  and supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process. The cycle of extracting 0.5 ml of additive B liquid Q 5  from the additive liquid tank  25  and supplying the extracted additive B liquid Q 5  to the measurement cell  10  and measuring an Ar value according to the CVS process is repeated a predetermined number of times (usually four times) to draw a calibration curve. The measured data are determined, and if the measured data are appropriate, then the liquid in the measurement cell  10  is drained and the interior of the measurement cell  10  is washed.  
      Then, it is confirmed again that the electrodes  12  are stable by extracting 50 ml of low-concentration basic liquid Q 1  from the low-concentration basic liquid tank  21 , supplying the extracted low-concentration basic liquid Q 1  to the measurement cell  10 , measuring an Ar value according to the CVS process, and confirming that the Ar value is an appropriate value.  
      If it is confirmed that the Ar value is an appropriate value, then the low-concentration basic liquid Q 1  is drained from the measurement cell  10  and the measurement cell  10  is washed. Thereafter, 99.6 ml of sample plating liquid is extracted and supplied to the measurement cell  10 , and 1 ml of additive A liquid Q 4  is extracted from the additive liquid tank  24  and added to the liquid in the measurement cell  10 . An Ar value is measured according to the CVS process, and a carrier concentration of the sample plating liquid is measured from the calibration curve shown in  FIG. 2  based on the measured Ar value.  
      [Leveler Concentration Measuring Mode] 
      A leveler concentration can be measured according to three methods. These leveler concentration measuring methods will be described below.  
      In an example of the leveler concentration measuring method according to the invention, it is confirmed that the electrodes  12  are stable by extracting 100 ml of low-concentration basic liquid Q 1  from the low-concentration basic liquid tank  21 , supplying the extracted low-concentration basic liquid Q 1  to the measurement cell  10 , measuring an Ar value according to the CVS process, and confirming that the Ar value is an appropriate value.  
      If it is confirmed that the Ar value is an appropriate value, then the low-concentration basic liquid Q 1  is drained from the measurement cell  10  and the measurement cell  10  is washed. Thereafter, 48 ml of high-concentration basic liquid Q 2  is extracted from the high-concentration basic liquid tank  22 , 1 ml of additive A liquid Q 4  is extracted from the additive liquid tank  24 , and 1 ml of additive B liquid Q 5  is extracted from the additive liquid tank  25 . The extracted liquids are supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process.  
      Then, 0.1 ml of additive C liquid Q 6  is extracted from the additive liquid tank  26  and supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process. The cycle of extracting 0.1 ml of additive C liquid Q 6 , supplying the extracted additive C liquid Q 6  to the measurement cell  10 , and measuring an Ar value according to the CVS process is repeated a predetermined number of times (usually four times) to draw a calibration curve as shown in  FIG. 2 . The measured data are determined, and if the measured data are appropriate, then the liquid in the measurement cell  10  is drained and the interior of the measurement cell  10  is washed.  
      50 ml of sample plating liquid is extracted and supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process. A leveler concentration of the sample plating liquid is measured from the calibration curve shown in  FIG. 2  based on the measured Ar value. If the Ar value of the sample plating liquid is represented by y in  FIG. 2 , then the corresponding leveler concentration is determined as x.  
      In a further leveler concentration measuring method, after it is confirmed that the electrodes  12  are stable, a certain amount of high-concentration basic liquid Q 2  is extracted from the high-concentration basic liquid tank  22 , and a certain amount of additive B liquid Q 5  is extracted from the additive liquid tank  25  such that its concentration is 2 to 40 times the above concentration (high-concentration basic liquid Q 2 +additive B liquid Q 5 =50 ml). The extracted liquids are supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process.  
      Then, 0.1 ml of additive C liquid Q 6  is extracted from the additive liquid tank  26  and supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process. The cycle of extracting 0.1 ml of additive C liquid Q 6  and supplying the extracted additive C liquid Q 6  to the measurement cell  10  and measuring an Ar value according to the CVS process is repeated a predetermined number of times (usually four times) to draw a calibration curve (not shown). The measured data are determined, and if the measured data are appropriate, then the liquid in the measurement cell  10  is drained and the interior of the measurement cell  10  is washed.  
      50 ml of sample plating liquid is extracted and supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process. A leveler concentration of the sample plating liquid is measured from the calibration curve based on the measured Ar value.  
      In a leveler concentration measuring method according to the present invention, after it is confirmed that the electrodes  12  are stable, 49 ml of high-concentration basic liquid Q 2  is extracted from the high-concentration basic liquid tank  22 , and 1 ml of additive A liquid Q 4  is extracted from the additive liquid tank  24 . The extracted liquids are supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process.  
      Then, 0.1 ml of additive C liquid Q 6  is extracted from the additive liquid tank  26  and supplied to the measurement cell  10 , and an Ar value is measured according to the CVS process. The cycle of extracting 0.1 ml of additive C liquid Q 6  and supplying the extracted additive C liquid Q 6  to the measurement cell  10  and measuring an Ar value according to the CVS process is repeated a predetermined number of times (usually four times) to draw a calibration curve (not shown). The measured data are determined, and if the measured data are appropriate, then the liquid in the measurement cell  10  is drained and the interior of the measurement cell  10  is washed.  
      50 ml of sample plating liquid from which the carrier has been removed by passing the plating liquid through an organic anion-selective adsorption film is extracted and supplied to the measurement cell  10 . An Ar value is measured according to the CVS process, and a leveler concentration of the sample plating liquid is measured from the calibration curve based on the measured Ar value.  
      With a number of leveler calibration curves for different carrier and polymer concentrations being stored in the computer of the controller  42 , the concentration measuring apparatus of the above construction is capable of analyzing samples easily within a short period of time.  
      According to the above methods of measuring the concentration of a leveler, it is possible to measure the concentration of a leveler in a plating liquid, which could not heretofore be measured according to the CV or CVS process.  
       FIG. 3  is a diagram showing an arrangement of a plating liquid managing apparatus which incorporates the automatic analyzing device for plating liquids shown in  FIG. 1 . The plating liquid managing apparatus has a plating tank  110  holding a plating liquid Q therein. An anode electrode plate  111  and a substrate  112  to be plated are placed in the plating tank  110  so as to confront (face) each other. When a plating current is supplied between the anode electrode plate  111  and the substrate  112  to be plated from a plating power supply E, the surface of the substrate  112  is plated according to an electroplating process.  
      A plating liquid adjusting tank  113  for adjusting a plating liquid can be supplied with a standard liquid Q 11  from a standard liquid tank  114  through a pump P 1  and a valve V 1 , a replenishing liquid Q 12 , which comprises the basic liquid and the additive A mixed therein, from a first replenishing liquid tank  115  through a pump P 2  and a valve V 2 , a replenishing liquid Q 13 , which comprises the basic liquid and the additive B mixed therein, from a second replenishing liquid tank  116  through a pump P 3  and a valve V 3 , a replenishing liquid Q 14 , which comprises the basic liquid and the additive C mixed therein, from a third replenishing liquid tank  117  through a pump P 4  and a valve V 4 , sulfuric acid (H2SO4) Q 15  from a sulfuric acid tank  118  through a pump P 5  and a valve V 5 , and hydrochloric acid (HCl) Q 16  from a hydrochloric acid tank  119  through a pump P 6  and a valve V 6 .  
      A plating liquid Q 17  which has been adjusted in the plating liquid adjusting tank  113  is supplied to the plating tank  110  through a filter  120  by a pump P 7 . The plating liquid Q in excess of a certain level in the plating tank  110  is returned to the plating liquid adjusting tank  113 . Therefore, the plating liquid circulates between the plating liquid adjusting tank  113  and the plating tank  110 .  
      The plating liquid Q 7  supplied to the plating tank  110  is sampled by a sampling device  121 . The components of the plating liquid Q 17  sampled by the sampling device  121  are automatically analyzed by an automatic analyzing device  122 . The plating liquid managing apparatus has a drain tank  123 , and a level sensor  124  for measuring a plating liquid level in the plating liquid adjusting tank  113 , and a controller  125 .  
      The controller  125  receives the analyzed results of the components of the plating liquid  17  analyzed by the automatic analyzing device  122  and the plating liquid level measured by the level sensor  124 . Based on the analyzed results of the components of the plating liquid Q 17  analyzed by the automatic analyzing device  122 , the controller  125  controls the pumps P 1 -P 6  and the valves V 1 -V 6  to control the standard liquid Q 11  supplied from the standard liquid tank  114 , the replenishing liquid Q 12  supplied from the replenishing liquid tank  115 , the replenishing liquid Q 13  supplied from the replenishing liquid tank  116 , the replenishing liquid Q 14  supplied from the replenishing liquid tank  117 , the sulfuric acid Q 15  supplied from the sulfuric acid tank  118 , and the hydrochloric acid Q 16  supplied from the hydrochloric acid tank  119  so as to adjust the components of the plating liquid Q 17  in the plating liquid adjusting tank  113 .  
      The plating liquid managing apparatus thus constructed operates as follows: When a plating process is to be started, certain amounts of replenishing liquids Q 12 , Q 13 , Q 14  with the additives A, B, C mixed therewith may be added to the standard liquid Q 11  from the standard liquid tank  114 . The automatic analyzing device  122  automatically analyzes the concentrations of the additive A (polymer), the additive B (carrier), and the additive C (leveler), as described above, and also automatically analyzes the concentrations of Cu2+, H2SO4, and Cl—. These concentrations may automatically be analyzed according to a titrimetric analyzing process or a spectrophotometric analyzing process.  
      At the time of starting the plating process, since a variation of the concentrations of the components vary greatly, the sampling frequency for sampling the plating liquid with the sampling device  121  is set to a high value. While in the plating process, the replenishing liquids Q 12 , Q 13 , Q 14  and the hydrochloric acid Q 16  are individually supplied to the plating liquid Q 17  in the plating liquid adjusting tank  113  in order to keep the concentrations of the components within a certain management range depending on the analyzed results from the automatic analyzing device  122 .  
      When the concentrations of the components are stabilized, the sampling frequency for sampling the plating liquid with the sampling device  121  is set to a lower value, e.g., once every few hours. At this time, a process of supplying the replenishing liquids Q 12 , Q 13 , Q 14  from the replenishing liquid tanks  115 ,  116 ,  117  at predetermined periods of time may be combined to compensate for the consumed amounts of additives that are empirically known depending on the quantity of electricity.  
      The plating liquid Q in the plating tank  110  is partly removed out of the system depending on the number of substrates  112  that are plated. The consumption of the components of the additives is also substantially proportional to the number of substrates  112  that are plated (integrated current value). Therefore, the removed amount of plating liquid and changes in the volumes of the additives can be kept in balance by properly adjusting in advance the concentrations of the components to be added.  
      For example, if the additives A, B, C are to be uniformly replenished, then the concentrations of the replenishing liquids Q 12 , Q 13 , Q 14  are given as follows: 
 
Concentration of an additive (mg/ml) in the component replenishing liquid=consumed amount (mg)/[removed amount×⅓ (ml)]
 
      Actually, since the components in the plating liquid are reduced in fluctuations, the concentrations are made greater than, (e.g., about twice), the concentration given by the above equation, and the amounts of the component replenishing liquids of the additives are reduced and the replenishing liquid Q 11  is replenished as the remainder. In this manner, the replenishing liquids in the adjusting tanks are prevented from being excessive.  
      With the above method of and apparatus for managing the plating liquid, as described above, component replenishing liquids comprise a standard liquid, a plurality of solutions of a basic liquid with a plurality of different additives added thereto, sulfuric acid, and hydrochloric acid, either wholly or partly. The component replenishing liquids are supplied to a plating liquid by a component replenishing liquid supply device. The additive can easily be managed individually, and the concentrations of the components can be managed more strictly. Thus, it is possible to produce uniform and homogeneous films of plated copper to provide highly reliable copper interconnections.  
     INDUSTRIAL APPLICABILITY  
      The present invention can be used to measure the concentration of a leveler in a plating liquid that is used by a plating apparatus for filling metal such as copper in interconnection trenches and holes defined in the surface of a semiconductor substrate or the like, and also to manage a plating liquid to manage the components thereof.