US20080237066A1

US20080237066A1 - Electrolytic processing unit device, and method for electrolytic processing, washing, and drying

Info

Publication number: US20080237066A1
Application number: US12/004,562
Authority: US
Inventors: Takashi Fujita; Kyouji Watanabe
Original assignee: Tokyo Seimitsu Co Ltd
Current assignee: Tokyo Seimitsu Co Ltd
Priority date: 2007-03-26
Filing date: 2007-12-21
Publication date: 2008-10-02
Also published as: JP2008240037A; TW200847257A; JP5116330B2; DE102007057297A1; KR20080087648A

Abstract

An electrolytic processing unit device includes an electrolytic processor for performing electrolytic processing on a wafer, a washer for washing the processed wafer, and a drier for drying the wafer. The electrolytic processor, the washer, and the drier are placed in one processing chamber to form one module. In this manner, the electrolytic processing procedure, the washing procedure, and the drying procedure for wafers can be continuously carried out in one place.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an electrolytic processing unit device, and a method for electrolytic processing, washing, and drying. More particularly, the present invention relates to an electrolytic processing unit device that is used for performing electrolytic processing, washing, and drying for wafers, and a method for the electrolytic processing, washing, and drying.
2. Description of the Related Art
In a conventional CuCMP electrolytic polishing, for example, the series of procedures for electrolytic processing, washing, and drying for each wafer is carried out in modules that are independent of one another. Therefore, each wafer needs to be transported through the corresponding module in each of the procedures for electrolytic processing, washing, and drying. Accordingly, the number of wafer transporting procedures between the modules is large.
Particularly, in the electrolytic processing for each wafer, the wafer transportation system becomes more complicated, as the wafer is normally turned over so as to process both sides of the wafer.
If some trouble is caused in one of the modules while a wafer is being transported sequentially to the respective modules of the respective procedures for performing electrolytic polishing on the wafer, the trouble leads to a large problem. For example, if trouble is caused in the module of the washing procedure during a processing operation, and the operator does not notice the trouble and cannot cope with the trouble immediately, the wafer transportation system is stopped in the module of the washing procedure, and this delay affects the modules of the other procedures. As the transportation systems of the other modules are also stopped, all the wafers being transported along the process line are stopped. The stopped wafers are left in contact with the outer air and the process liquids over a long period of time, and problems such as oxidation degradation and corrosion are caused.
To avoid the above problems, there has been a method suggested for activating the program for production control so as to immediately stop the transportation of wafers in the modules of all the procedures and keep the wafers away from the process line when trouble is caused during the electrolytic processing procedure (see Japanese Patent Application No. 2002-178236, for example).
However, creation of the above program is very complicated according to a method such as the above described method by which the transportation of wafers in the modules is immediately stopped and the wafers are kept away from the process line when trouble is caused. In a conventional CMP device, mechanical processing is performed mostly on wafers, and a platen for rotating the wafer polishing pad is required. However, an electrolytic processing device does not require the platen.
If there is trouble in the last drying procedure in a case where an operation is performed in modules for procedures of processing, washing, and drying in a device, many wafers are stopped within the device unless the trouble is eliminated. Particularly, if wafers are stopped and left in the processing procedure and the washing procedure, the surfaces of the wafers might be oxidized, or the surfaces might be etched by the washing solution. As a result, the quality of the wafers might be degraded. In such a case, if even very small trouble caused in the initial stage is left unnoticed and wafers are stopped in the device, all the wafers in the device might be wasted, which is a serious problem.
In view of these facts, since trouble in one of the modules for procedures greatly affects the other wafers when a large number of wafers are processed at once, close attention needs to be paid to operations of the device. Therefore, unmanned operations have been impossible in practice.
In a Cu low-k process, the atmosphere in the wafer electrolytic processor needs to be made different from the air, so as to prevent oxidation of the surface of the wafer especially during the electrolytic processing. Further, in the drying procedure after the washing, the atmosphere in the electrolytic processor also needs to be made different from the air, so as to reduce watermarks.
If the atmosphere control is performed in many modules, the atmosphere controller becomes very large in size. Also, if the atmosphere control is performed every time a wafer is brought in or out in each procedure, a very long period of time is required. If the atmosphere control needs to be performed only once for the series of procedures for processing, washing, and drying, a very efficient operation can be realized.
Where two or more modules are prepared for two or more procedures, devices for transporting each wafer between the modules are necessary. Those transporting devices are very costly. Moreover, at the time of maintenance, all the procedures for wafers are interrupted, and the operation rate of the device becomes lower.
Further, in a conventional electrolytic processing operation, it has been difficult to perform Cu electrolytic processing and Ta electrolytic processing on each wafer in the same position.
Even in electrolytic processing, a mechanism for energization is provided in a chemical mechanical polishing device to perform electrolytic processing. As the pad for chemical mechanical polishing, a regular polishing pad is used. However, when Ta polishing is performed after Cu polishing, the Cu polishing waste adversely affects the Ta polishing. For example, the Ta polishing rate might change, or the Cu polishing waste might adhere to the Ta surface. Also, in a case where the electrolytic solution for Cu polishing is different from the electrolytic solution for Ta polishing, the two electrolytic solutions might be mixed with each other on the polishing pad. Therefore, in a case where electrolytic polishing is performed with a polishing pad, it is difficult to perform both Cu polishing and Ta polishing in one module.
Likewise, in a case where the polishing procedure and the polishing procedure are carried out in one module, electrolytic solutions and abrasive grains existing on the polishing pad cause the washing environment to deteriorate.
As disclosed in U.S. Pat. No. 7,084,064 and Japanese Patent Application Laid-open No. 2006-135045, it has been almost physically impossible to combine an electrolytic processing device and a washing device into one by conventional techniques. This is because an electrolytic processing device has a platen, and processes the entire surface of each wafer at once. Normally, a wafer is held by a wafer head provided above the wafer, and a platen is placed under the wafer. In this case, polishing is performed, with the wafer being held to face downward.
The wafer may be also washed while facing downward, but a washing solution cannot be applied to the surface of the wafer in this situation in reality.
In an electrolytic processing device disclosed in Japanese Patent Application Laid-open No. 2002-93761, the electrode portion is processed above a wafer while being swept. However, since each wafer is processed while being immersed in an electrolytic solution, it is difficult to incorporate the washing procedure and the drying procedure into the electrolytic processing procedure.
To combine an electrolytic processing device, a washing device, and a drying device, the same technique should be utilized for clamping wafers in those devices. Also, to transport wafers to wafer chucks, a transportation mechanism that does not physically interfere with the electrolytic processing unit, the washing unit, and the likes needs to be prepared.
However, it has been impossible to realize all of those functions, and combine all the modules into one module structure. Also, it has been physically difficult to combine the modules for supplying electrolytic solutions, controlling electrolytic processing, and washing wafers, into one.
Also, if a polishing slurry or the like remains in the unit for electrolytic processing, the polishing slurry dries and adheres to the wall faces of external units. The dry polishing slurry turns into power dust that lies scattered about in the module. As a result, it is difficult to keep a clean environment for the washing device.
In view of these facts, an electrolytic processing device and washing and drying devices for washing and drying each wafer to a normal state before each wafer is sent back to the semiconductor factory cannot be placed in one module by conventional techniques. If those devices are forced into one module, a clean environment cannot be kept.
Also, if trouble is caused in one of the procedures of electrolytic processing, washing, and drying for wafers in a case where those procedures are combined into one module, the transportation of wafers being transported in other modules is not stopped. If the other wafers are stopped, the surface of each wafer is reformed. In this case, small trouble results in significant trouble that ruins all the wafers.

SUMMARY OF THE INVENTION

The object of the present invention is to solve the above problems. More specifically, according to the present invention, the procedures being carried out sequentially in a device are not interrupted, and the operation rate does not rapidly drop. Instead, each module performs an operation independently of other modules. If there is some trouble caused in one module, the other modules keep operating. In this manner, the entire operation rate does not rapidly drop, and a stable operation rate is kept. Also, wafer transporting devices for connecting modules for the respective procedures are not required, and an increase in device size due to the transporting devices can be prevented.
Also, according to the present invention, the atmosphere in the electrolytic processing procedure does not adversely affect the atmosphere in the later washing procedure, or particles are not scattered about. The adverse influence of the atmosphere in the electrolytic processing procedure is the problem normally expected from a combination of the electrolytic processing procedure and the washing and drying procedures by a conventional technique. The present invention also eliminates the adverse influence of the contamination caused by the Cu material that is dissolved by an electrolytic solution and adheres back to the surface. By doing so, the electrolytic solution having been used for electrolytic processing cannot be brought into the next electrolytic processing procedure and the next washing procedure.
In a case where each wafer is transported to more than one module for more than one procedure, all the wafers being transported in the device are temporarily stopped every time a maintenance operation is performed, and the operation rate of the device becomes lower. The present invention is to solve those technical problems.
The present invention has been made to solve the above problems, and according to a first aspect of the present invention, there is provided an electrolytic processing unit device including: an electrolytic processor that performs electrolytic processing on a wafer; a washer that washes the processed wafer; and a drier that dries the processed or washed wafer, the electrolytic processor, the washer, and the drier being placed in a processing chamber to form one module that performs the electrolytic processing, washing, and drying for the wafer.
In this structure, the electrolytic processing unit device has the electrolytic processor, the washer, and the drier placed in one processing chamber to form one module. Accordingly, the wafer electrolytic processing, washing, and drying can be continuously performed in one place. Also, even if some trouble is caused in one module, the trouble does not affect other modules at all, and it is not necessary to stop the wafer processing procedures in other modules.
According to a second aspect of the present invention, there is provided the electrolytic processing unit device according to the first aspect, wherein the electrolytic processor, the washer, and the drier are aligned on a circular arc or a straight line.
In this structure, the electrolytic processor, the washer, and the drier of the electrolytic processing unit device are arranged along a circular arc or a straight line. Accordingly, when a wafer is transported to the electrolytic processor, the washer, and the drier, only one robot that can move along the circular arc or the straight line is required for the wafer transportation.
According to a third aspect of the present invention, there is provided the electrolytic processing unit device according to the first or second aspect, wherein the electrolytic processor, the washer, and the drier form one module, and are connected to each other by one transportation system.
In this structure, the electrolytic processor, the washer, and the drier of one module are connected by one transportation system. Accordingly, only one device is required for transporting wafers to the electrolytic processor, the washer, and the drier. Thus, each wafer can be transported to the electrolytic processor, the washer, and the drier in a sequential manner.
According to a fourth aspect of the present invention, there is provided the electrolytic processing unit device according to any of the first to third aspects, wherein the electrolytic processor, the washer, and the drier that carry out the above series of procedures are controlled, operated, and subjected to maintenance independently of one another.
In this structure, the electrolytic processor, the washer, and the drier can be operated, controlled, and subjected to maintenance independently of one another. Accordingly, when one of the electrolytic processor, the washer, and the drier is operated, controlled, and subjected to maintenance, the other procedures do not need to be stopped.
According to a fifth aspect of the present invention, there is provided the electrolytic processing unit device according to the first or second aspect, wherein a beveling unit for beveling an outer peripheral portion of the wafer after the electrolytic processing is provided in the vicinity of the electrolytic processor.
In this structure, when the conductive film on the surface of the wafer is removed from the center toward the outer peripheral portion of a wafer, a ring-like portion of the conductive film remains at the outer peripheral portion of the wafer. However, the ring-like conductive film is beveled by etching or mechanical processing performed by a beveling unit provided in the vicinity of the electrolytic processor. Accordingly, each wafer subjected to electrolytic processing is not moved away from the electrolytic processor, and is then subjected to beveling.
According to a sixth aspect of the present invention, there is provided the electrolytic processing unit device according to any of the first, third and fourth aspects, wherein the module includes: an access area through which wafers are brought in and out; an electrolytic processing head for electrolytic processing that is provided in a different area from the access area, and a holding arm that holds the electrolytic processing head; and a washing arm that supports a wafer washing unit is provided in the opposite position from the holding arm.
In this structure, a washing arm supporting a wafer washing unit is provided in the opposite position from the holding arm that holds the electrolytic processing head. Accordingly, washing of each wafer is performed at a spot separated from the spot for electrolytic processing.
According to a seventh aspect of the present invention, there is provided the electrolytic processing unit device according to the sixth aspect, wherein the wafer washing unit in the module includes a washing brush, a ultrasonic water supplier, and a nitrogen blower.
In this structure, the wafer washing unit includes a washing brush, a ultrasonic water supplier, and a nitrogen blower. Accordingly, the electrolytic solution remaining on the surface of the wafer is removed by washing with the brush and ultrasonic washing, and the space surrounding the wafer cannot become an oxygen atmosphere at the time of washing.
According to an eight aspect of the present invention, there is provided an electrolytic processing unit device including: an electrolytic processor that performs electrolytic processing on a wafer; a washer that washes the processed wafer; and a drier that dries the processed or washed wafer, the electrolytic processor, the washer, and the drier being placed in a processing chamber to form one module that performs the electrolytic processing, washing, and drying for the wafer, an electrode portion for the electrolytic processing being made of an inorganic material.
This structure has the same effects as the first aspect of the invention, and the electrode portion for electrolytic processing is made of an inorganic material. Unlike a case with an electrode portion made of an organic material, the old electrolytic solution used for electrode processing can be easily rinsed off from the electrode portion, and the old electrolytic solution cannot remain at the electrode portion.
According to a ninth aspect of the present invention, there is provided a method for electrolytic processing, washing, and drying in a structure having a wafer chuck mechanism, including the steps of: performing electrolytic processing by applying a voltage between an electrode having edges clamped around a wafer and an electrolytic processing head that scans the surface of the wafer, after securing the wafer; polishing a conductive film at an edge portion in the same position, if necessary, while a bottom face of the wafer is being sucked and fixed after an edge clamp is removed; scanning the surface of the wafer with a washing arm in the same position, a washing unit being attached to the washing arm; washing the processed wafer; and drying the processed or washed wafer in the same position.
By this method, the series of procedures of electrolytic processing, edge processing, washing, and drying for wafers can be carried out in the same place. Accordingly, wafers do not need to be moved for each procedure.
According to a tenth aspect of the present invention, there is provided the method according to the ninth aspect, wherein the surface of the wafer and an electrode portion are rinsed with pure water, after the electrolytic processing procedure and the washing procedure.
By this method, the surface of each wafer and the electrode portion are rinsed with pure water after electrolytic processing and washing. Accordingly, the electrolytic solution and chemical solution (washing solution) remaining on the surface of the wafer can be removed after the electrolytic processing and washing of the wafer.
According to the first aspect of the invention, electrolytic processing, washing, and drying for each wafer can be performed in one place. With this arrangement, a large space is not required, and each wafer does not need to be transported through more than one module as in the prior art. Accordingly, the mechanism such as a wafer transporting device can be omitted. Also, even if some trouble is caused in one module, the wafers being transported through the process line do not need to be stopped by interrupting the operation of the transportation systems of other modules. Thus, oxidation degradation and corrosion due to the interruption are not caused in wafers, and it is unnecessary to create a complicated program.
According to the second aspect of the invention, each wafer can be transported to the electrolytic processor, the washer, and the drier by one robot. With this structure, the same effects as those of the first aspect of the invention can be achieved, and the wafer transporting mechanism can be made simpler than a conventional one. Also, the electrolytic processor, the washer, and the drier can be arranged along a circuit arc or a straight line, in accordance with the situation and objective. Thus, a higher degree of freedom is allowed in the arrangement of the electrolytic processor, the washer, and the drier.
According to the third aspect of the invention, only one device is required for transporting wafers to the electrolytic processor, the washer, and the drier. With this structure, the same effects as those of the first or second aspect of the invention can be achieved, and the costs for the wafer transportation can be reduced. Also, the operation rate of the wafer transportation system can be made higher.
According to the fourth aspect of the invention, even when one of the electrolytic processor, the washer, and the drier is being operated, controlled, or subjected to maintenance, the operations and the likes in other procedures are not interrupted and can be continued. With this structure, the same effects as those of any of the first to third aspects of the invention can be achieved, and the operating rates of the electrolytic processor, the washer, and the drier can be made higher than in conventional cases.
According to the fifth aspect of the invention, the conductive film remaining at the outer peripheral portion of each wafer after electrolytic processing can be subjected to beveling performed by the beveling unit provided in the vicinity of the electrolytic processor. With this structure, the beveling can be performed immediately after the electrolytic processing. Thus, the same effects as those of the first or second aspect of the invention can be achieved, and higher efficiency can be expected in the beveling process.
According to the sixth aspect of the invention, the washing of each wafer can be performed at a spot separated from the spot for electrolytic processing. With this structure, the same effects as those of any one of the first, third, and fourth aspects of the invention can be achieved, and the electrolytic solution used for electrolytic processing cannot be brought into the washer.
According to the seventh aspect of the invention, the electrolytic solution remaining on each wafer can be removed by washing with the brush and ultrasonic washing, and the space surrounding each wafer cannot become an oxygen atmosphere during the washing. With this structure, the same effects as those of the sixth aspect of the invention can be achieved, and the effectiveness of washing each wafer can be increased. Thus, adverse influence of an oxygen atmosphere on each wafer can be eliminated in advance.
According to the eighth aspect of the invention, the same effects as those of the first aspect of the invention can be achieved. More specifically, the mechanism for wafer transportation can be omitted, and oxidation degradation and corrosion of wafers can be prevented. Also, it becomes unnecessary to create a complicated program. In addition to those effects, the old electrolytic solution used for electrode processing does not remain at the electrode portion. Accordingly, when electrode processing is performed with a new electrolytic solution, the old electrolytic solution does not react with the new electrolytic solution, and does not adversely affect the electrolytic processing.
The tenth aspect of the present invention provides the method for electrolytic processing, washing, and drying according to the ninth aspect, characterized in that the surface of each wafer and the electrode portion are rinsed with pure water after the electrolytic processing procedure and the washing procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an exemplary structure of an electrolytic processing unit device in accordance with an embodiment of the present invention;

FIG. 2 is a cross-sectional view showing the electrolytic processor of the electrolytic processing unit device of FIG. 1;

FIG. 3 is a schematic perspective view illustrating a state formed by processing of the electrolytic processing unit device of the embodiment;

FIG. 4 is a flowchart showing an example of processing procedures to be carried out by the electrolytic processing unit device of this embodiment;

FIG. 5 is a plan view showing an example arrangement of an electrolytic processing unit device of the present invention;

FIG. 6 is a plan view showing another example arrangement of an electrolytic processing unit device of the present invention; and

FIG. 7 is a plan view showing yet another example arrangement of an electrolytic processing unit device of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

To combine the wafer electrolytic processing procedure, the washing procedure, and the drying procedure into one module, to prevent each wafer from stopping in other modules even if some trouble is caused in one of the procedures, and to make a complicated program unnecessary, the present invention provides an electrolytic processing unit device that includes an electrolytic processor for performing electrolytic processing on a wafer, a washer for washing the processed wafer, and a drier for drying the processed or washed wafer, and performs the electrolytic processing, the washing, and the drying of the wafer in one module that is realized by placing the electrolytic processor, the washer, and the drier in one processing chamber.

Embodiment

The following is a description of a suitable embodiment of the present invention, with reference to FIGS. 1 through 7. This embodiment is applied to an electrolytic processing unit device that performs electrolytic processing, washing, and drying of a wafer formed with conductive films. FIG. 1 is a plan view showing an exemplary structure of the electrolytic processing unit device in accordance with this embodiment. FIG. 2 is a cross-sectional view showing the electrolytic processor of the electrolytic processing unit device of FIG. 1. FIG. 3 is a schematic perspective view illustrating a state formed by processing of the electrolytic processing unit device. FIG. 4 is a flowchart showing an example of processing procedures to be carried out by the electrolytic processing unit device. FIGS. 5 through 7 are plan views each showing an example of arrangement of an electrolytic processing unit device of the present invention.
As shown in FIG. 1, the electrolytic processing unit device 1 includes an electrolytic processor 2 that performs electrolytic processing on a wafer W, a washer 3 that washes the processed wafer W, and a drier 4 that dries the processed or washed wafer W. The electrolytic processor 2, the washer 3, and the drier 4 are placed in a processing chamber (a cleaning room) 5, and the wafer W is transported to the processing chamber 5 by a transfer robot 6. With this arrangement, the series of procedures of electrolytic processing, washing, and drying of the wafer W can be carried out in the processing chamber 5. The modules for processing procedures that have been three or more in number by a conventional technique are integrated into one.
In this electrolytic processing unit device 1, electrolytic processing, washing, and drying of the wafer W are carried out in predetermined order by the electrolytic processor 2, the washer 3, and the drier 4.
In the electrolytic processor 2, a carbon electrode is attached to the top end of the arm. This carbon electrode may have a brush-like form or a felt-like form. Alternatively, the carbon electrode may be in a thin, tile-like form. If the carbon electrode is brought into direct contact with the wafer, the wafer is damaged. Therefore, the carbon electrode is processed in a semi-contact state via a thin electrolyte film. Here, electrolytic dissolution processing is mainly performed. Instead of a carbon electrode, a wire rod made of a metal material may be used.
In any case, the electrode should not be made of a material containing an electrolytic solution, like a polymeric polishing pad. A polishing pad used in chemical mechanical polishing is made of foamed polyurethane, which contains a polishing agent. When a polishing material is processed with an electrolytic solution, the old electrolytic solution contained in the polishing pad might exude and react with the new electrolytic solution.
Therefore, it is necessary to use an inorganic material that does not contain a used electrolytic solution and is not an organic material. With an inorganic material, even if an electrolytic solution containing abrasive grains is used for example, the electrode portion is rinsed in advance. In this manner, the electrolytic solution can be easily rinsed off, and, as a washing atmosphere, does not adversely affect the next washing process.
After the electrolytic processing, pure water is supplied to the surface of the wafer W from a pure water nozzle (not shown) directed to the surface of the wafer W, and the entire surface of the wafer W is thoroughly rinsed. Through this rinsing process, the electrolytic solution remaining on the surface of the wafer W is replaced with pure water. Also, a shower nozzle for supplying pure water to be used for washing is provided within a cup (not shown) surrounding the wafer W. This shower nozzle is designed to thoroughly rinse off the electrolytic solution scattering from the wafer W inside the cup.
The electrode used for the electrolytic processing and provided at the top end of the arm is removed from the position for processing the wafer W. A pot filled with pure water is prepared in a stand-by position at a distance from the wafer processing position. The electrode material is immersed in the pure water in the pot, so that the electrolytic solution remaining on the electrode is washed off. Pure water is constantly supplied into the pot, so that the pot is always in an overflowing state. Even if the electrode material is a carbon brush or the like, the electrolytic solution remaining between the bristles of the brush due to a capillary absorption phenomenon is thoroughly rinsed off by ultrasonic waves.
In the above described structure, the mechanism for rinsing the surface of the wafer W and the electrode material is provided so as not to leave the electrolytic solution in the later washing procedure after the electrolytic processing. With this structure, the electrolytic processing state is not continued into the next washing procedure, and washing can be performed in a clean environment.
The electrolytic processor 2 performs primary processing and secondary processing so as to remove a conductive film from the surface of the wafer W. Also, a beveling unit 7 is provided in the electrolytic processor 2, and the beveling unit 7 performs beveling on the edge portions remaining on the outer peripheral portion of the wafer W after the removal. Further, an application mechanism (not shown) for applying an antioxidant solution to the wafer W after the secondary processing is completed is provided in the electrolytic processor 2.
FIGS. 2 and 3 show a specific example of the electrolytic processor 2. Reference numeral 8 indicates a wafer holding table that has the wafer W placed and fixed thereon, and can be rotatively driven. A fixing unit 9 for placing and fixing the wafer W is provided at the upper face portion of the wafer holding table 8. In the example shown in the drawings, a vacuum chuck unit is provided.
Further, a processing head 10 is provided above the wafer holding table 8. As shown in FIG. 3, a processing electrode 11 is provided at the top end of the processing head 10, so as to face the upper face of the wafer W, with a very small space being left between the processing electrode 11 and the upper face of the wafer W. The processing head 10 is attached to a movable member 12 such as an arm or a slider provided in the vicinity of a side of the wafer holding table 8. In the example shown in the drawings, the processing head 10 is attached to the top end of the double-arm movable member 12, and the base portion of the movable member 12 is linked to the upper portion of a vertical axis 13 having an adjustable height. The base portion of the movable member 12 is connected to the upper portion of the vertical axis in a horizontally rotatable fashion. Accordingly, the processing head 10 is horizontally rotated from the center of the wafer W toward the outer peripheral portion, so that the processing electrode 11 moves outward in the radial direction of the wafer W.
At the outer peripheral portion of the wafer W, there are six detachable wafer chucks 21 through 26 that rotate integrally with the wafer holding table 8. These wafer chucks 21 through 26 are arranged at regular intervals in the outer circumferential direction of the wafer W. Also, the wafer chucks 21 through 26 can move back and forth, and are adjustable up and down with respect to the outer peripheral portion of the wafer W on the wafer holding table 8. Further, supply electrodes A through F for supplying power to the wafer W are provided inside the respective wafer chucks 21 through 26. Each of the supply electrodes A through F is sealed and protected, so as to prevent liquid and the likes from entering the supply electrodes A through F. A tester (not shown) for measuring the mutual electric resistance is interposed between each two of the supply electrodes A through F. Alternatively, one tester may be provided to check the resistance between each two of the supply electrodes A through F by switching the electrodes.
A voltage is applied between the processing electrode 11 and the supply electrodes A through F by a DC low-voltage supply 15, and an electrolytic solution (a slurry) 17 is supplied onto the upper face of the wafer W by a supply nozzle 16. The electrolytic solution 17 may suitably be phosphoric acid, sodium nitride, ammonium chloride, sulfuric acid, hydrochloric acid, or a mixed solution of them.
The electrode portion is made of carbon or the like. If a hydroplane state is formed with the water film of the electrolytic solution 17 when an electrode is brought close to the wafer W, the interelectrode space can be made very small, and the convex portion on the wafer W is electrolytically concentrated. Thus, only the convex portion can be selectively processed and removed.
The electrode portion should desirably have a flat shape with respect to the surface of the wafer W facing the electrode. If the electrode becomes large in size, however, the relationship between the electrode and the surface of the wafer W becomes equal to a relationship between flat faces, and the electrode might be partially brought into contact with the surface of the wafer W. If there is a contact, short-circuiting might be caused, and the wafer W is damaged by the hard carbon. Therefore, it is preferable that the electrode area is made so small that there is not a contact portion in the plane, while the very small space is maintained. The desirably effective electrode area is approximately +20 mm.
In a case where only the electrolytic dissolution processing is performed, a nonconductive film might be formed on the surface, particularly with Cu, Ta, or the like. In such a case, the current might rapidly decrease, and the processing might not proceed at a certain spot. In this case, an electrode in the form of a carbon brush is suitable as the electrode. With a brush-like shape, the top end of the electrode is in contact with the surface of the wafer W. However, when an electrolytic solution is supplied while the wafer W is rotated, the top end is not completely in contact with the surface of the wafer W, and a very small space is maintained between the electrode and the surface of the wafer W.
For example, if a carbon brush is formed with brushes each having a large number of thin bristles of approximately 0.15 mm tied together, constant pressure is applied onto the surface of the wafer W from the top end of one brush, though the pressure is very small as each brush bends. With this pressure, an even smaller space is formed between the wafer W and the carbon brush electrode. Due to the space, electrolytic processing can be selectively performed on the convex portion of the wafer W.
At the time of electrolytic processing, while the electrolytic solution 17 is being supplied between the rotating wafer W and the processing electrode 11, electrolytic polishing is performed by applying a voltage, so that the conductive film on the upper face of the wafer W can be evenly removed. In this case, the processing electrode 11 is gradually scan-moved from the center of the wafer W toward the outer peripheral portion.
The processing is completed at the center of the wafer W, and the processed region is widened toward the outer peripheral portion. In this manner, uniform processing can be performed on the entire surface of the wafer W. When scanning is performed with the movable member (arm) 12 having the processing electrode 11, the scan speed should be changed in accordance with the processed state of the wafer W.
The processed state of the surface of the wafer W can be monitored by a sensor attached to the scan arm for the electrolytic processing. The sensor can sense changes in the color of the surface of the wafer W. In a case where the wafer W is made of Cu, a clear change in the film color can be observed when the type of film is switched from a Cu film to a Ta film.
As the sensor that can sense changes in the color of the surface, a spectrometer or the like may be used. With a spectrometer, light is dispersed by a prism or grating, and the intensity distribution of the dispersed light at each wavelength is measured with the use of a Linear Image Sensor S3901/S3904 series (manufactured by Hamamatsu Photonics K. K.). In this manner, changes in the film color can be detected with high precision.
After the electrolytic processing, a rinsing procedure is carried out to remove the electrolytic solution 17 from the surface of the wafer W. In the rinsing procedure, the surface of the wafer W is rinsed, and pure water is sprayed to the wafer chucks 21 through 26 and the inside of the process washing cup provided below them, so as to rinse off the wafer chucks 21 through 26 and the inside of the process washing cup.
In the washer 3, the wafer W after the electrolytic processing is washed with a pen brush. The pen brush is suitably a sponge made of polyvinyl alcohol (PVA). First, the wafer W is rotated, and a washing chemical solution or water is supplied to the portion surrounding the center of the surface of the wafer W. The wafer W is then scanned with the pen brush, so that the surface of the wafer W can be cleaned (the primary washing).
There might be particles remaining on the surface of the wafer W even after the washing. In such a case, the surface of the wafer W should be rinsed with pure water. Particularly, when the wafer W is washed with ultrasonic waves, the particles remaining on the surface of the wafer W can be completely removed (the secondary washing).
The pen brush and the ultrasonic generator are attached to the top end 20 of a washing movable arm 19 that is horizontally rotatable about a vertical axis 18. The washing movable arm 19 is provided in the vicinity of the other side of the wafer holding table 8. Accordingly, the pen brush and the ultrasonic generator provided at the top end 20 of the movable arm 19 moves in the radial direction of the wafer W, as the washing movable arm 19 is horizontally rotated.
Also, there are cases where the remnant cannot be removed by physical washing with the pen brush, depending on the material. To counter such a situation, a chemical nozzle (not shown) is provided and is directed toward the wafer W. Particularly, the additive component and the dissolved metal component of the electrolytic solution might become a contaminating component and adversely affect the wafer W.
To eliminate such a contaminating component of the wafer W, an acidic chemical solution such as hydrofluoric acid or hydrochloric acid may be used, or an alkaline chemical solution such as ammonia may be used. The contamination is removed with such a chemical solution and the pen brush, and at the same time, the particles remaining on the surface of the wafer W may be removed.
The used chemical solution is also drained off, coming into contact with the cup surrounding the wafer W. Also, the scattered chemical solution is constantly rinsed off with a pure water shower within the cup. Accordingly, when electrolytic processing is performed again, the chemical solution used for the washing does not have adverse influence.
In the procedure for rinsing off the used chemical solution, pure water washing may be performed with ultrasonic waves. With ultrasonic waves, the chemical solution remaining on the surface of the wafer W can be more effectively rinsed off, and the chemical solution remaining inside the cup can be completely washed away.
In the drying procedure to be carried out at last, the surface of the wafer W is rinsed with pure water. Immediately after that, spin drying can be performed. The wafer chucks 21 through 26 can revolve, with the maximum number of revolutions being 2000 rpm.
A polishing head and a polishing platen that are normally used in electrolytic polishing are very large and heavy, and as a result, produce a vibration in the entire device when revolving at a high speed. However, with the light-weight wafer chucks 21 through 26 in accordance with the present invention, washing can be performed after electrolytic processing, and drying is then performed by spinning the wafer chucks 21 through 26 at a high speed, with the maximum number of revolutions being 2000 rpm.
In a process using a low-k material, the surface of the wafer W has water repellency, and therefore, a watermark sometimes appears. In such a case, normal spin drying is not suitable. One of the reasons for the appearance of a watermark is that water is not removed as a whole but is divided into droplets of water due to the water repellency of the surface of the wafer W. It is believed that those droplets absorb oxygen, and the water containing oxygen reacts with the low-k material to form a silicon oxide with a different composition.
To counter this problem, the entire module for electrolytic processing and washing and drying is formed in a sealed container housing that is compact in size. The housing is designed to serve as a pressure container that can withstand up to 10 Pa. Particularly, in the last drying procedure, spin drying should be performed with a pressure increased to approximately 8 Pa in a nitrogen atmosphere.
In a nitrogen atmosphere, a silicon oxide that forms unnecessary watermarks due to the oxygen contained in pure water is not formed on the surface of the low-k material. Also, with the increased pressure, the contact angle of the water is increased, and an environment that is not water repellent in appearance can be formed. With such an environment, formation of watermarks can be prevented even when spin drying is performed.
By another method for preventing formation of watermarks due to spin drying, alcohol such as IPA may be incorporated into the pure water to be supplied in the rinsing procedure prior to the spin drying. The water containing IPA increases the wetness of the surface of the wafer W, and dramatically increases the contact angle. As a result, even after normal spin drying is performed, watermarks are not formed on the surface of the wafer W, and a dry surface can be maintained.
In the wafer drier 4, the washed wafer W is subjected to spin drying. In this case, the wafer chucks 21 through 26 attached during the electrolytic processing may be detached or may not be detached from the wafer W. After that, the wafer W is spun around, so that the electrolytic solution and water remaining on the surface of the wafer W can be thrown off and eliminated.
Instead of pure water, an aqueous solution containing alcohol may be used. With such an aqueous solution, the surface tension can be reduced, and the spin drying becomes easier. Particularly, for a low-k material having a water-repellent surface, such a process is suitable.
Referring now to FIG. 4, an example of the operation of processing the wafer W in accordance with this embodiment is described. First, the wafer W is transported to the processing chamber 5 by the robot 6, and is placed on the wafer holding table. The wafer W is then fixed to the wafer holding table by the wafer chucks 21 through 26. This fixing is performed to bring the power supply unit into contact with the surface of the wafer W at the same time as the fixing. Also, the fixing is performed to secure the wafer W at the center of the wafer holding table. The vacuum chuck of the wafer holding table forms a vacuum for the secured wafer W, so as to firmly attach the wafer W onto the wafer holding table 8.
While an electrolytic solution is being applied onto the surface of the wafer W, the processing electrode 11 attached to the top end of the scan arm is caused to act on the surface of the wafer W, so that electrolytic processing is performed. In the electrolytic processor 2, the conductive film (a Cu film or a Ta film) on the surface of the wafer W is removed by electrolytic polishing. More specifically, a voltage is applied between the rotating wafer W and the processing electrode 11 while the electrolytic solution 17 is being supplied, and the processing electrode 11 is caused to scan the wafer W from the center toward the outer periphery of the wafer W. In this manner, the conductive film on the surface of the wafer W is gradually and evenly removed from the center toward the outer periphery of the wafer W (step S1).
After the conductive film is evenly removed from the center to the outer periphery of the wafer W, an anticorrosion solution is applied from the center to the outer periphery of the wafer W. The ring-like Cu film remaining at the outer periphery of the wafer W at the end of the electrolytic processing is removed by etching or mechanical processing in the beveling unit 7 (step S2).
The wafer W subjected to the electrolytic processing is not moved and remains in the same position. The wafer W is then washed by the washer 3 as a different arm from the scan arm for the electrolytic processing. More specifically, the pen brush is brought into contact with the surface of the wafer W, and the surface of the wafer W is washed by jetting a washing solution or pure water. After that, the surface of the wafer W is rinsed with pure water having ultrasonic waves applied thereto (steps S3 and S4).
The washed wafer W is then subjected to spin drying in the drier 4. More specifically, the wafer W is spun around on the wafer holding table 8, so that the electrolytic solution 17 and water remaining on the surface of the wafer W are thrown off due to the centrifugal force (step S5).
As described above, in this embodiment, the electrolytic processor 2, the washer 3, and the drier 4 are placed in the processing chamber 5, so as to form one module. Accordingly, not only the entire device and the space for the device can be made smaller, but also the electrolytic processing, the washing, and the drying of the wafer W can be sequentially performed in one place in a continuous manner.
To maintain cleanness, a downward air current is supplied to the module that performs the electrolytic processing, the washing, and the drying of the wafer W, from the above via a hepafilter. Accordingly, the wafer W and its surrounding area are constantly in a clean air current. Thus, after the drying of the wafer W at last, the wafer W having a clean surface without remnant particles can be transferred to the transportation robot.
To counter the problem of watermarks at the time of electrolytic processing or washing and drying, N₂blowing may be performed on the wafer W and its surrounding area in the module. A N₂nozzle to introduce liquid nitrogen is placed on the wafer W, and cooled N₂is supplied to the wafer W and its surrounding area. In this manner, the wafer W and its surrounding area can be separated and isolated from the atmosphere containing oxygen.
Since there is no oxygen in the atmosphere, oxidation of the Cu surface can be prevented during the electrolytic processing, and formation of watermarks formed by the oxygen that is contained in the pure water and reacts with the surface of the low-k material can be prevented during the wafer drying procedure.
Accordingly, even if some trouble is caused in one of the electrolytic processor 2, the washer 3, and the drier 4 of the module, the trouble does not adversely affect the processing procedures in other modules. Therefore, it is not necessary to interrupt the processing procedures in other modules, and oxidation degradation and corrosion due to the interruption are not caused. Furthermore, it is not necessary to prepare a complicated program.
FIGS. 5 and 6 show other examples of the electrolytic processing unit device 1 in accordance with the present invention. In these examples, the electrolytic processor 2, the washer 3, and the drier 4 are arranged in a circular arc or in a straight line in the processing chamber 5. The wafer W is transported to the electrolytic processor 2, the washer 3, and the drier 4 by a double-arm robot 27 that can move in a desired direction (can move straight and spin around). It is also possible to provide two robots 27 that are interposed between electrolytic processors 2, washers 3, and driers 4, as shown in FIG. 7. The two robots 27 are designed to move independently of each other.
In any of these structures, electrolytic processing, washing, and drying of the wafer W can be performed with one module. Accordingly, even if some trouble is caused in the module, the processing of other wafers W in other modules is not interrupted. Furthermore, the mechanism of rotating a polishing pad that is necessary in a conventional CMP device can be omitted, and the amount of mechanical processing can be reduced. Thus, the device mechanism can be simplified and made more lightweight.
Unlike a conventional structure having more than one module for each of the procedures of electrolytic processing, washing, and drying, the device in accordance with the present invention does not require a mechanism for transporting each wafer W between the modules. Thus, the mechanism and the processing program can be further simplified.
In the above described embodiment, the number of electrolytic processors, the number of washers, and the number of driers in one electrolytic processing unit device are one. However, it is possible to employ two or more electrolytic processors, two or more washers, and two or more driers, if necessary.
As described above, in the present invention, the electrolytic processor, the washer, and the drier that form one module are connected by one transportation system. Accordingly, only one device for transporting the wafer W to the electrolytic processor, the washer, and the drier is required. With the one device for transportation, the wafer W can be continuously transported to the electrolytic processor, the washer, and the drier. Thus, the costs for the wafer transportation system can be reduced, and the operation rate of the wafer transporting device can be made higher.
Furthermore, the electrolytic processor, the washer, and the drier can be operated, controlled, and subjected to maintenance independently of one another. Accordingly, when one of the electrolytic processor, the washer, and the drier is operated, controlled, or subjected to maintenance, the operations at the other components do not need to be stopped. Thus, the operating rates of the electrolytic processor, the washer, and the drier can be made higher.
Further, the washing arm supporting the wafer washing unit is provided to face the arm that holds the electrolytic processing head, so that the wafer W is washed at a spot separated from the spot for the electrolytic processing. Thus, the electrolytic solution used for the electrolytic processing cannot be brought into the washer.
Since the wafer washing unit includes a washing brush, a ultrasonic water supplier, and a nitrogen blower, the electrolytic solution remaining on the surface of the wafer W can be removed by brush washing and ultrasonic washing, and the space surrounding the wafer W cannot become an oxygen atmosphere during the washing. Thus, the effectiveness of washing the wafer W is increased, and the wafer W is not adversely affected by an oxygen atmosphere.
Since the electrode portion is made of an inorganic material, the old electrolytic solution used for electrode processing cannot remain at the electrode portion. Accordingly, when electrolytic processing is performed with a new electrolytic solution, a reaction between the new electrolytic solution and the old electrolytic solution can be prevented.
Furthermore, the series of procedures of electrolytic processing, edge processing, washing, and drying for the wafer W are carried out in the same position. Accordingly, the wafer W does not need to be moved for each procedure, and the series of procedures can be carried out in a continuous manner.
In this embodiment, the surface of the wafer W and the electrode portion are rinsed with pure water after electrolytic processing and washing. Through the rinsing, the electrolytic solution and chemical solution remaining on the surface of the wafer W at the time of electrolytic processing and washing can be thoroughly removed. In this manner, degradation of the processing quality of the wafer W due to the electrolytic solution and chemical solution can be effectively prevented.
It should be understood that various changes and modifications may be made to the above embodiments, without departing from the scope of the invention, and the present invention is applicable to the changes and modifications.

Claims

1. An electrolytic processing unit device comprising:

an electrolytic processor that performs electrolytic processing on a wafer;

a washer that washes the processed wafer; and

a drier that dries the processed or washed wafer,

the electrolytic processor, the washer, and the drier being placed in a processing chamber to form one module that performs the electrolytic processing, washing, and drying for the wafer.

2. The electrolytic processing unit device according to claim 1, wherein the electrolytic processor, the washer, and the drier are aligned on a circular arc or a straight line.

3. The electrolytic processing unit device according to claim 1 or 2, wherein the electrolytic processor, the washer, and the drier form one module, and are connected to each other by one transportation system.

4. The electrolytic processing unit device according to any of claims 1 through 3, wherein the electrolytic processor, the washer, and the drier that carry out the above series of procedures are controlled, operated, and subjected to maintenance independently of one another.

5. The electrolytic processing unit device according to claim 1 or 2, wherein a beveling unit for beveling an outer peripheral portion of the wafer after the electrolytic processing is provided in the vicinity of the electrolytic processor.

6. The electrolytic processing unit device according to any of claims 1, 3, and 4, wherein

the module includes: an access area through which wafers are brought in and out; an electrolytic processing head for electrolytic processing that is provided in a different area from the access area, and a holding arm that holds the electrolytic processing head; and

a washing arm that supports a wafer washing unit is provided in the opposite position from the holding arm.

7. The electrolytic processing unit device according to claim 6, wherein the wafer washing unit in the module includes a washing brush, a ultrasonic water supplier, and a nitrogen blower.

8. An electrolytic processing unit device comprising:

an electrolytic processor that performs electrolytic processing on a wafer;

a washer that washes the processed wafer; and

a drier that dries the processed or washed wafer,

the electrolytic processor, the washer, and the drier being placed in a processing chamber to form one module that performs the electrolytic processing, washing, and drying for the wafer,

an electrode portion for the electrolytic processing being made of an inorganic material.

9. A method for electrolytic processing, washing, and drying in a structure having a wafer chuck mechanism, comprising the steps of:

performing electrolytic processing by applying a voltage between an electrode having edges clamped around a wafer and an electrolytic processing head that scans the surface of the wafer, after securing the wafer;

polishing a conductive film at an edge portion in the same position, if necessary, while a bottom face of the wafer is being sucked and fixed after an edge clamp is removed;

scanning the surface of the wafer with a washing arm in the same position, a washing unit being attached to the washing arm;

washing the processed wafer; and

drying the processed or washed wafer in the same position.

10. The method according to claim 9, wherein the surface of the wafer and an electrode portion are rinsed with pure water, after the electrolytic processing procedure and the washing procedure.