KR20050019749A - Device and method for monitoring an electrolytic process - Google Patents

Abstract

In manufacturing integrated circuits, gaps may be readily formed in the metal layer during the electrolytic metal coating. To avoid such defects that adversely affect the functionality of an integrated circuit, the present invention includes one or more anodes and one or more cathodes, and one or more reference electrodes disposed on the surface of one or more anodes or on the surface of one or more cathodes. It is proposed to use an electrolysis device for metal coating. Voltmeters are provided respectively for detecting voltages between one or more anodes and one or more reference electrodes and between one or more reference electrodes and one or more cathodes.

Description

DEVICE AND METHOD FOR MONITORING AN ELECTROLYTIC PROCESS}

Specification:

The present invention relates to an apparatus and method for monitoring an electrolysis process, and more particularly, to an apparatus and method for electrolytically coating a metal on a substrate.

More specifically, integrated circuits on a wafer made of silicon are generally manufactured using etching and deposition processes together with photolithographic processes. To date, it has conventionally formed metallic conductive patterns using sputter processes to establish electrical conductor connections on the wafer. Over the years, galvanic processes have been increasingly used to fabricate integrated circuits on wafers. In addition to the so-called "back end" portion, i.e. electrolytic deposition of copper for wiring semiconductor structures formed on the wafer, also called "packeting" processes, i.e. chip carriers In the case of coating metals on carriers and in rewiring, metal coatings of copper, nickel, gold and tin are becoming increasingly important. In addition, all these requirements have in common that an electrolytic metal deposition process is initiated on a thin starting metal layer, the so-called seed layer, called a plating base. For this purpose, the starting layer is placed in electrical contact with suitable mechanical contacts and the starting layer is placed in an electroplating bath containing the metal to be coated in solution. The current flows through the start layer and the counter electrode using a counter electrode and an external current source, such as a rectifier that applies a voltage by an electrical network, so that a metal is coated on the wafer's start layer. . The amount of metal covered and the coating thickness are controlled by Faraday's law.

Coating thickness distribution on the wafer may be significantly affected using suitable shields or segmented anodes (opposing electrodes). Therefore, in order to maintain a constant concentration of metal ions in an electrolyte fluid, soluble anodes are used, and in other cases, if the metal ion content must be kept constant, insoluble ( Additional inert anodes.

U. S. Patent No. 5,234, 572 discloses a method for refilling metal ions in a plating bath. US Pat. No. 5,234,572 discloses a cathode (opposing electrode) using a reference electrode made of the same metal as the anode and additionally installed in the plating bath to control the amount of electricity transferred between the cathode and the anode when current is introduced. (Measurement) equipment for measuring the potential of The amount of electricity to be conducted is controlled so that the potential of the measured counter electrode does not become negative with respect to the reference electrode. As a result, metal ions are not coated on the counter electrode. In a preferred exemplary embodiment, the counter electrode and the soluble electrode (anode) are connected to a DC source. A voltmeter is used to measure the potential of the opposite electrode relative to the reference electrode. In the figure, the potentials at the opposite and soluble electrodes that change with the flow of current are shown.

In the case of electrolytic copper cladding, German Patent No. 199 15 146 C1 discloses that a copper clad bath comprises, for example, Fe (III) compounds in addition to the general bath constituents, and these compounds contain copper pieces. It is mentioned that Fe (II) compounds are produced in this process by dissolution to form copper ions. The Fe (II) formed is reoxidized to Fe (III) compounds at insoluble anodes.

All known electroplating baths contain auxiliary agents which affect the metal coating in addition to the metal ions to be coated. In general, these agents are on the one hand organic compounds that affect the structure of the coating layer and on the other hand are salts, acids or bases added for the purpose of stabilizing the bath and increasing the electrical conductivity. As a result, the voltage required for the coating is reduced, thus generating minimal Joule heat. This increases the stability of the process. Some processes are only possible when adding these agents.

Generally, conductive patterns are fabricated according to the current damascene process. As mentioned in German patent 199 15 146 C1, a dielectric layer is first applied to a semiconductor substrate for this purpose. Vias and trenches needed to accommodate the desired conductive patterns are typically etched in the dielectric layer using a dry etch process. After the diffusion barrier (in most cases tantalum nitride, tantalum) and the conductive layer (in most cases sputtered copper) are applied, the recesses, ie vias and trenches, are (trench filling process) to electrolytically fill. As the entire surface is coated with copper, the excess must be removed from unwanted locations, subsequently meaning from the outer region of the vias and trenches. This can be achieved by using the so-called CMP process (C hemical M echanical P olishing) . By repeating the above process, i.e. made of silicon dioxide and forming the recesses by etching, multilayer circuits are produced by repeatedly applying and then coating copper.

More specifically, after forming the conductive pattern made of copper, in the polishing sections to be controlled, metal defects (voids) are easily formed in the coated structures, and It can be found that the defects lead to the functional destruction of the entire circuit.

Accordingly, a problem faced by the present invention is to avoid the deficiencies of known apparatus and methods, and more particularly to provide methods for reliably preventing such defects from forming.

To overcome this problem, the present invention provides an apparatus according to claim 1 and a method according to claim 7. Preferred embodiments of the invention are shown in the dependent claims.

The apparatus according to the invention serves to monitor the electrolytic metallization process during the fabrication of circuit structures on chip carriers and integrated circuits of semiconductor substrates (wafers), more specifically the electrolytic process. .

To describe the invention in more detail, hereafter, the term "wafer" is used to refer to any workpiece. Similarly, the term "deposition electrolyte" or "coat electrolyte fluid" is used to refer to the electrolyte fluid used to perform the electrolysis process. Alternatively, if the electrolysis process is an electrolysis etch process, the fluid may also be an etch fluid. Possible electrolysis processes are electrolytic coating methods and electrolytic metal etching methods. In principle, the invention may also be used for other electrolysis processes other than the processes mentioned herein. In the detailed description that follows, the term "electrolytic coating process" is used for all other electrolytic processes.

To overcome the above problems, the present invention provides an apparatus and method. The device consists of one or more anodes and cathodes in contact with the electrolyte fluid, in which a flow of current occurs. One or more reference electrodes are disposed on the surface (nearby) of the at least one anode or on the surface (near) of at least one cathode. According to the invention, there is further provided a voltmeter for determining respective voltages between the at least one anode and at least one reference electrode and between the at least one reference electrode and at least one cathode. This configuration allows simultaneous representation of partial processes of electrolysis at the various electrodes and also allows time-varying processes to be measured by this provision. Thus, it does not matter whether the electrodes are only immersed into the electrolyte fluid during the measurement, or whether a voltage is applied between the cathode and the anode only when the cathode and the anode are in contact with the electrolyte fluid.

In a preferred application of the device according to the invention, the cathode is a wafer or chip carrier substrate and the anode is a metal plate. In this case, preferably during the electrolysis process, the metal is coated on the wafer or chip carrier.

The device according to the invention is more particularly composed of at least one first reference electrode disposed on the surface (near) of at least one anode, and at least one second reference electrode disposed on the surface (near) of at least one cathode. . Voltmeters are further provided for measuring voltages between the one or more anodes and one or more first reference electrodes, between the first and second reference electrodes, and between the second reference electrode and one or more cathodes. The monitoring device measures the voltage between the anode and the first reference electrode, between the first reference electrode and the second reference electrode, and between the second reference electrode and the cathode electrode.

Extensive tests have shown that defects (gaps) in the coated metal layers are due to the fact that the metal coating bath used can remove metal from the starting layers under any condition conditions.

When the wafer provided with the starting metal layer is immersed in the metal coating solution, no external voltage is initially applied to the starting layer. Thus, as soon as the starting layer and the electrolyte solution come into contact, an equilibrium potential is established between them. Under general conditions applied for coating metal, more particularly copper on the starting layer, the starting layer dissolves slowly in the coating solution because the potential of the starting layer is positive for metal dissolution.

In general, the metal starting layers used on wafers are very thin due to cost and process related reasons. For example, in general structures made for this damascene process (eg, trenches, vias 0.1-0.2 μm wide and 1 μm deep), the starting layer is generally about 5-25 nm thick. Is formed. In contrast, the starting layers on the surface of the wafers are about 100 nm thick. Layers of this type can be quickly removed at least in their structures while immersed in the electrolyte solution because the etch rate in the electrolyte solutions used is very fast. In a typical copper electrolyte containing about 180 g / l sulfuric acid and 40 g / l copper in the form of copper sulfate, the etch rate is about 10 nm / min under typical electrolysis conditions. Under these conditions, the coating thickness remaining before metal coating is not sufficient to ensure a reliable metal coating under any circumstances. The etch rate depends in particular on the type of inter alia, the type of electrolyte solution used, the conditions chosen for the coating process and the type of starting layer.

This problem reduces the time between the immersion and the start of the coating process, for example, because it must maintain any minimum processing time after immersion, in order to completely wet the wafer to be coated with fluid before starting the metal coating. Can't be solved. Thus, the time window available for the process of electrolytically coating the metal on the starting layer is only a narrow window. A unique problem due to the multiple variables that affect is that the size of the time window for the process cannot be determined, so the results of metallization are left to chance.

The thin starting layer is particularly susceptible to changes in the coating process and corrosion. This slight reduction in layer thickness may, for example, sufficiently threaten the safe initiation of the process in nanostructures.

Therefore, it is very important to precisely control the immersion and wetting procedures. Technically, this control is not easy due to the lack of electrical contact between the electrolyte fluid and the wafer prior to immersion and the electrolyte dependent equilibrium potential obtained after immersion. The starting layer, depending on the composition of the electrolyte, may corrode significantly more or less to an unpredictable degree.

More specifically, it is known that the parameters affecting metal removal are partial voltages that add up to generate the total voltage (clamp voltage) applied between the anode and the cathode.

During the electrolytic metal sheathing, a current flows between the anode and the cathode. To generate the flow of current, a voltage consisting of the sum of the partial voltages mentioned is required. More specifically, the voltage is the sum of anode and cathodic charge transfer overvoltage, polarization overvoltages, and crystallization overvoltages, and also concentration overvoltages ( concentration overvoltages) and voltage drops due to electrolyte resistance and voltage drops in electrical feed lines.

In general, it is not known how to divide the measurable clamp voltage between the respective voltages. More specifically, since only the clamp voltage of the current source, which is a rectifier, is known, for example, variations in distribution cannot be exhibited. During cladding, if at least one of the mentioned resistors or the overvoltage of one of the overvoltages described changes or varies between the various wafers being processed, at most, the resulting clamp voltage It is impossible to interpret measurable changes. Even in the worst case, such a change cannot be found and the metal is removed without the possibility of finding it.

In semiconductor technology, process stability and reproducibility for the above methods are of the utmost importance, and means must be sought for means that can represent partial voltages. Changes during the process must be interpreted and identified to allow for control and modification of the process.

Using reference electrodes disposed directly on the surface of the anode or cathode, at least detect changes in voltage drop due to electrolyte resistance. For this purpose, reference electrodes can be brought close to the surfaces and the potential can be measured directly at each surface of the surfaces. For example, the reference electrodes are arranged close to each surface of the surfaces with a spaced space smaller than 1 mm, for example 0.2 mm. Also in more detail, the reference electrodes may be arranged directly in proximity to the horizontal plane of the surface of the anode and cathode other than the surface, but not the front of the surface. Thus, it is not necessary to place the reference electrodes in contact with the surfaces. Another possibility is to install a small container containing the conductive electrolyte on or near each surface so that the potential at the surface can be detected by the reference electrode in the container.

In a preferred embodiment of the present invention, two reference electrodes are provided, wherein a first reference electrode of the two reference electrodes is disposed on the surface of the anode and the second reference electrode is disposed on the surface of the cathode. By placing the two reference electrodes in close proximity to each of the electrodes (anode and cathode), it is possible to separately detect the effect of the voltage drop due to the resistance of the electrolyte in the form of a voltage between the two reference electrodes. have. At the surface on which the reference electrodes are arranged, other voltage drops measured between the electrodes of each of the reference electrodes and an anode or cathode, voltage drops occurring in the vicinity of the anode or cathode surface, more specifically charge transfer, crystallization and Concentration overvoltages.

Thus, it is possible to detect various voltage drops in different regions of the electrolytic cell, thereby separating the influence of the aforementioned factors (such as the type of electrolyte solution, the properties of the starting layer, etc.). Can be detected and analyzed Thus, by identifying changes due to the mentioned affecting variables, appropriate provisions can be made in the case of such changes.

An advantage of the present invention is that existing electroplating plants can easily be improved by means of the present invention, since no substantial structural extension is necessary.

To measure the changes mentioned, any reference electrode can be used. More specifically, stable reference electrodes contain a hardly soluble salt of the metal and the metal in equilibrium with the electrolyte. For example, this type of electrode includes electrodes of the second or third order that provide a constant potential. Secondary reference electrodes are reference electrodes in which the concentration of the potential-determining ions is determined by the presence of a poorly soluble compound, and the ions of the poorly soluble compound are the same as the potential-determining ions. . In contrast, tertiary reference electrodes are reference electrodes whose activity of the potential-determining ions is determined by the presence of two solid phases. More specifically, the secondary reference electrodes are calomel electrode, silver / silver chloride electrode, mercuric sulfate electrode and mercuric oxide electrode. . The third reference electrodes may be zinc rods that are in parallel with the calcium ion solution in the presence of a precipitate consisting of zinc and calcium oxalate, for example.

One reference electrode is installed in proximity to the anode and the other is installed in proximity to the wafer. During the electrolysis process, the process is controlled by measuring the voltage between the anode and the first reference electrode, between the first reference electrode and the second reference electrode, and between the second reference electrode and the cathode.

The voltage measured between the first reference electrode and the second reference electrode is the result of a change in electrolyte resistance which indicates an unstable component of the electrolyte or an irregular flow in the processing tank.

In addition, changes in voltage measured between the first reference electrode and the anode indicate instability of the anode process. When using a soluble anode, this may be due to the consumption of the anode, the change in the anode film, and the varying anode geometry of the anode. For example, if the method described in German Patent No. 100 15 146 C1 is carried out, using an inert (insoluble) anode, this change in measured voltage is (e.g. For example, the active anode layer may be flawed, or the provision of a sparse redox species to the anode, such as, for example, Fe (II) and Fe (III) compounds It may be indicated.

Changes in the voltage measured between the second reference electrode and the cathode are, for example, cathodic processes such as variations in the thickness of the starting layer because the starting layer has been invaded by a metal coating solution or this layer did not have sufficient thickness. Indicates instability.

In order to control the process, more particularly, to prevent the starting layer from corroding, before immersion, between the starting layer and the reference electrode closest to it by a power rectifier, for example a second reference electrode. The voltage difference can be applied to. By selecting the appropriate starting layer potential, it is possible to prevent corrosion of the starting layer during immersion and to prevent corrosion of the starting layer even in the wet state. In order to obtain useful measurement results, each electrode of the reference electrodes should be as close as possible to the associated electrode. However, the workpiece (eg cathode) and the counter electrode (eg anode) must be protected so that the metal to be coated is distributed as uniformly as possible.

More specifically, since the stable reference electrodes contain a poorly soluble metal salt and a metal in parallel with the electrolyte, there is a risk that the electrolyte of the electrolysis process is contaminated by the electrolyte of the reference electrode. Such contamination should be prevented by all means. In addition, to solve this problem, the reference electrode is in contact with the surface of the anode or cathode through one or more capillaries. Only a very small current flows in the measurement configuration, since the voltage measurement between the reference electrodes and between each electrode of the reference electrodes and between the anode and the cathode is respectively a high resistance measurement. Thus, the capillary tube can be made very thin so that contamination of the electrolyte of the electrolysis process by the electrolyte of the reference electrodes is minimized.

Another improvement associated with this problem may be achieved in that each individual electrode of the reference electrodes is supplied with an electrolyte fluid of an electrolysis process via the capillary. Thus, the electrolyte of the reference electrode is prevented from penetrating into the coating electrolyte by diffusion.

In order to electrolytically coat metal onto a semiconductor substrate, more specifically to coat copper, for example, common electroplating configurations consisting of platinum include anode and semiconductor substrates facing parallel and horizontal or from a horizontal plane. It may also be used in an inclined state. The anode and the semiconductor substrate may also be oriented vertically. The two electrodes are arranged in a tank suitable for this purpose, such as, for example, a cylinder type tank, which contains the electrolyte fluid and the electrodes. In general, an anode is disposed on the bottom of the cylindrical tank, and a semiconductor substrate is disposed on the tank. In order to generate a defined fluid flow, the electrolyte fluid can flow through the tank in any manner. The reference electrodes may be installed in separate containers in communication with the cylindrical tank with the mentioned capillaries. Capillaries are disposed on the wall of the tank so as to be located directly in proximity to each of the electrodes.

Another advantage of the present invention is that it can be controlled through the possibility that any voltages (potentials) can be measured simultaneously, even in the various partial processes described as the apparatus and method according to the invention take place at various electrodes. Is there. This provision can locate the problem in the current transfer.

The present invention will be described in more detail with reference to the following drawings.

1 is a schematic cross-sectional view of a structure (trench, via) in a dielectric on a semiconductor substrate.

FIG. 2 is a diagram schematically illustrating the potential difference in an anode and cathode configuration having respective reference electrodes provided in proximity to the anode and also in proximity to the cathode.

3 is a schematic cross-sectional view of the covering cell.

4 is a schematic cross-sectional view of a covering cell for problem analysis of current fluctuations during coating.

1 shows the coating thickness distribution of the starting layer 2 near and within the structure 4 in the dielectric layer 3 on the semiconductor substrate. In this case, the structure 4 has an area of 0.2 μm and a depth of about 1 μm. At the surface of the substrate, the starting layer 2 is about 100 nm thick. The starting layer 2 is much thinner at the bottom of the structure. There it is only 5-25 nm thick. During immersion and subsequent wetting of the starting layer 2, the metal 2 is removed to some extent using a metal-coated electrolyte in this low region so that no metal remains at the bottom of the structure 4 or only very Only a thin layer is left. As a result, no metal can be coated on this area during the continuous electrolytic metal plating process.

2 schematically shows the potential difference between the anode 5 and the cathode 1 spaced into the space containing the electrolyte. The current delivered by the current source 6 flows between the anode 5 and the cathode 1. The current source 6 may be a power rectifier, for example. The voltage U delivered by the current source 6 is measured using the voltmeter 7. In addition, the voltage U is called clamp voltage.

The first reference electrode 8 is arranged in proximity to the anode 5. Similarly, the second reference electrode 9 is arranged in proximity to the cathode 1.

The potential difference in the space containing the electrolyte between the anode 5 and the cathode 1 is indicated by the reference numeral 10. For simplicity, the potential difference 10 is divided into only three parts 11, 12, 13, parts 11, 13 are caused by diffusion and crystallization overvoltages, and part 12 is the electrical From the voltage drop caused by the resistance.

The voltage drops mentioned are between the anode 5 and the first reference electrode 8 using the first voltmeter 14, the first reference electrode 8 and the second reference electrode (using the second voltmeter 15) Can be determined in a simple manner by measuring the voltage between 9) and between the second reference electrode 9 and the cathode 1 using a third voltmeter 16. The sum of the partial voltages 11, 12, 13 measured by the voltmeters 14, 15, 16 constitutes the clamp voltage U.

The voltage drop 11 is measured by the voltmeter 14, the voltage drop 12 by the voltmeter 15, and the voltage drop 13 by the voltmeter 16.

3 schematically shows a configuration for electrolytically coating a metal on the semiconductor substrate 1. The configuration includes a tank 20, an anode 5 on the bottom of the tank 20, and a semiconductor substrate 1 used as a cathode on top of the tank 20. Tank 20 is filled with electrolyte fluid 22 up to level 21. Fluid 22 can enter the tank 20 from the bottom, for example, and flows through the anode 5. For this purpose, the anode 5 is preferably drilled.

In the wall of the tank 20, the first capillary tube 23 is fitted close to the anode 5, and the second capillary tube 24 is fitted close to the semiconductor substrate 1. The electrolyte fluid flows through the capillaries 23, 24 into the reference electrode containers 25, 26 installed on their sides at a small volume flow. This prevents the introduction of electrolyte fluid into the tank 20 which may be contained in the vessels 25, 26 and having a different formulation than the coating fluid 22. The containers 25, 26 receive a first reference electrode 8 and a second reference electrode 9, which are connected to voltmeters (not shown) via wires.

4 schematically shows a covering cell. The anodes (5) are in the form of short or pellets by an inert anode basket which is surrounded by a diaphragm (not shown) and holds the coated metal. Is formed. The anodes 5 are located outside of the tank 20. These are connected by shields 28 through conduits 29 which are connected into the tank 20. Shields 28 act as actual anodes. The first reference electrode 8 is arranged in proximity to the anodes 5. Similarly, the second reference electrode 9 is arranged close to the cathode 1. Using the respective voltmeters 16, 15, 14, between the cathode 1 and the first reference electrode 8, between the second reference electrode 9 and the first reference electrode 8, and the first reference electrode The voltages between 8 and the anodes 5 are measured. Tank 20 is completely filled with electrolyte fluid 22.

In the tests actually carried out, it was shown that the amount of metal coated on the cathode 1 was not sufficient. At the same time, even though the voltage applied was 20V, a very small current of only about 100 mA was measured between the cathode 1 and the anodes 5 in comparison with typical covering cells (10 A at only 2-3 V). Thus, for this reason, for example,

1. insufficient electrical contact between the cathode 1 and the electrolyte fluid 22,

2. rupture of the conduits 29,

3. insufficient electrical contact between the anodes 5 and the electrolyte fluid 22, or

4. Flow rate of the insufficient electrolyte fluid through the conduits (29).

In designing the measuring equipment according to the invention, which comprises two reference electrodes 8, 9 and voltmeters 14, 15, the following results can be obtained simultaneously according to the invention in order to find a defect. It was possible.

 A voltage of about 0.5 V stabilized over time using the voltmeter 16 was measured between the cathode 1 and the second reference electrode 9. As measured by the voltmeter 15, the voltage between the two reference electrodes 8, 9 is 1V and settled over time. In contrast, the voltage between the first reference electrode 8 and the anode 5 is about 18.5 V and changed in time with the overall voltage.

These results exclude the reasons 1, 2, and 4 described above. The problem can be solved by improving the established electrical contact at the transition between the anodes 5 and the electrolyte fluid 22. It was found that the diaphragms disposed around the anode basket are no longer wet in the electrolyte fluid.

In a further example, an electrolytic copper bath 22 was used to coat the copper layer on the semiconductor wafer 1. A copper seed layer about 100 nm thick was provided on the wafer 1. The copper seed layer was coated with a photoresist layer having vias and trenches exposing the copper seed layer. Copper bath 22 generally contains small amounts of copper sulfate, sulfuric acid, and sodium chloride, as well as general additives used to optimize physico-mechanical properties. Bath 22 is operated in a cladding tank 20 having the design of the tank shown in FIG. The anode 5 consists of an expanded metal sheet of titanium and is insoluble, which activates the reaction with the noble metal (for example, platinum). In order to maintain a very small nominal copper ion concentration in the bath 22, copper pieces were dissolved in a separate vessel (not shown) in fluid connection with the tank 20. Also, in order to promote copper dissolution, the bath 22 contains Fe (II) and Fe (III) compounds. Baths suitable for this purpose are for example disclosed in German Patent No. 199 15 146 C1.

After the wafer 1 was introduced and brought into contact with the copper bath 22 and after some idle time had elapsed, the current was switched on so that the wafer 1 was metallized. Prior to switching on the current, the copper seed layer is in danger of being etched by the copper plating bath 22 or, more specifically, by Fe (III) ionic compounds in the bath. For this reason, electroplating becomes difficult if the copper seed layer is at least partially dissolved before the first copper coating.

Electroplating is affected by the electrolysis current flowing between the wafer 1 and the anode 5. By measuring the voltage between the wafer 1 and the reference electrode 9 over time to ensure that a safe wetting of the wafer 1 has occurred and that there is still a sufficiently thick copper seed layer on the surface of the wafer 1 Safe start to copper cladding can be easily determined. If it is not determined that the voltage is within the value of the expected range, insufficient electroplating is expected.

In addition, the voltage between the wafer 1 and the reference electrode 9 was also measured. This measurement was performed during the entire electroplating process to achieve the desired potential control for the wafer 1. This also ensured the stability of the process during the entire electroplating process including the method steps of dipping and wetting the wafer 1. It has been found that if a suitable voltage is applied to the wafer 1, etching of the seed layer can be prevented. Under these conditions, the wetting period of the wafer 1 can be optimized, i. E. Extended.

At the same time, it can also be seen that the processing is influenced by the imperderable conditions at the anode 5. The very high plating rate causes the mass transfer in the plating bath 22 to be a rate that determines (the reaction of Fe (II) to Fe (III)). This causes electrolysis of the water and results in oxygen gas bubbles at the anode 5. At the same time, the anode potential was measured to shift. Under unfavorable conditions, this change was detected by measuring the voltage between the anode 5 and the reference electrode 8. Thus, by identifying voltages outside the normal range, the processing parameters could be adjusted accordingly to prevent incomplete processing.

Thus, it has been found that if the above mentioned voltages and clamp voltages deviate from the normal range, processing defects caused by incomplete anode and / or cathode processes can be detected. By measuring these voltages at the same time as well as the clamp voltage between the wafer 1 and the anode 5, it was possible to determine the cause of the defect.

The examples and embodiments described herein are for illustrative purposes only and various modifications and changes as well as combinations of the features described in this application are apparent to those skilled in the art and are within the spirit and scope of the invention and the scope of the appended claims. Included. All publications, patents, and patent applications cited herein are incorporated by reference.

List of reference numbers

1 semiconductor substrate (cathode)

2 starting layer (seed layer, plating base)

3 dielectric layers

4 Structure in dielectric layer (3)

5 anode

6 Current source (voltage source)

7 Voltmeter for clamp voltage U

8 first reference electrode

9 second reference electrode

10 potential difference

11 Voltage drop at anode 5

12 Voltage drop in electrolyte 22

Voltage drop at 13 cathodes (1)

14, 15, 16 voltmeters

20 tank

21 fluid levels

22 electrolyte fluid

23, 24 capillaries

25, 26 reference electrode containers

27 wires

28 Shields (actual anode)

29 conduit

30 clamp voltage

Claims (12)

A device for monitoring the electrolysis process, One or more anodes and one or more cathodes, One or more reference electrodes disposed on the one or more anode surfaces or one or more cathode surfaces, and And one or more voltmeters respectively provided for detecting voltages between the one or more anodes and the one or more reference electrodes and between the one or more reference electrodes and the one or more cathodes. The method of claim 1, At least one first reference electrode is disposed on a surface of the at least one anode and at least one second reference electrode is disposed on a surface of the at least one cathode, A voltmeter is used to determine voltages between the one or more anodes and the one or more first reference electrodes, between the one or more first reference electrodes and the one or more second reference electrodes, and between the one or more second reference electrodes and the one or more cathodes. Respectively provided for detection. The method according to claim 1 or 2, And the one or more reference electrodes are in communication with the surface of the one or more anodes or the surface of the one or more cathodes through capillaries. The method of claim 3, wherein Apparatus is provided, through which capacitive electrolyte fluid can be delivered to the one or more reference electrodes. The method according to any one of claims 1 to 4, Wherein said at least one anode and said at least cathode are oriented parallel and horizontal or inclined from a horizontal line. The method according to any one of claims 1 to 5, Wherein said cathode is a wafer or chip carrier substrate and said anode is a metal plate. At least one anode and at least one cathode, One or more reference electrodes disposed on the surface of the one or more anodes or the surface of the one or more cathodes, and In an electrolytic cell having one or more voltmeters respectively provided for detecting voltages between the one or more anodes and the one or more reference electrodes and between the one or more reference electrodes and the one or more cathodes, As a method of monitoring the electrolysis process, The method, a) providing a flow of current between the at least one anode and the at least one cathode, and b) simultaneously detecting respective voltages between the one or more anodes and the one or more reference electrodes and between the one or more reference electrodes and the one or more cathodes. The method of claim 7, wherein At least one first reference electrode disposed on a surface of the at least one anode and at least one second reference electrode disposed on a surface of the at least one cathode, Step b) is b1) detecting a voltage between the at least one anode and the at least one first reference electrode,  b2) detecting a voltage between the at least one first reference electrode and the at least one second reference electrode, and b3) detecting a voltage between said at least one second reference electrode and said at least one cathode. The method according to claim 7 or 8, And the at least one reference electrode is in contact with the surface of the at least one anode or the surface of the at least one cathode through capillaries. The method of claim 9, And an electrolytic fluid is delivered through said capillaries to said at least one reference electrode. The method according to any one of claims 7 to 10, Wherein said at least one anode and said at least one cathode face parallel and horizontal or inclined from a horizontal line. The method according to any one of claims 7 to 11, The cathode is a wafer or chip carrier substrate and the anode is a metal plate, And the metal is electrolytically coated on the wafer.