JP2006128576A - Electrolytic processing apparatus and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further flatly process a surface while extremely reducing the contamination of the surface of a workpiece and suppressing the generation of a defect. <P>SOLUTION: The electrolytic processing apparatus includes a processing electrode 62 freely approachable to the workpiece W; a feeding electrode 64 for feeding electricity to the workpiece W; a power source 46 for applying a voltage between the processing electrode 62 and the feeding electrode 64; drive sections 56, 60 for moving the workpiece W and at least one of the processing electrode 62 and the feeding electrode 64 relative to each other; a liquid supply for supplying liquid between the workpiece W and at least one of the processing electrode 62 and the feeding electrode 64; a detector 80 for detecting a distance between the workpiece W and at least one of the processing electrode 62 and the feeding electrode 64; and a control unit 38 for controlling the distance S between the workpiece W and at least one of the processing electrode 62 and the feeding electrode 64, so as to be kept to a prescribed value which is 100 μm or below in a way that workpiece W and at least one of the processing electrode 62 and the feeding electrode 64 are not in contact with each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrolytic processing apparatus and an electrolytic processing method, and is particularly used for processing a conductive material formed on the surface of a substrate such as a semiconductor wafer or removing impurities adhering to the surface of the substrate. The present invention relates to an electrolytic processing apparatus and an electrolytic processing method.

  In recent years, as a wiring material for forming a circuit on a substrate such as a semiconductor wafer, the movement of using copper (Cu) having low electrical resistivity and high electromigration resistance instead of aluminum or an aluminum alloy has become prominent. . This type of copper wiring is generally formed by embedding copper in a fine recess provided on the surface of the substrate. Methods for forming this copper wiring include chemical vapor deposition (CVD), sputtering, and plating, but in any case, copper is deposited on almost the entire surface of the substrate, and chemical mechanical polishing is performed. Unnecessary copper is removed by (CMP).

FIG. 1A to FIG. 1C show a manufacturing example of this type of copper wiring board W in the order of steps. First, as shown in FIG. 1A, an insulating film 2 such as an oxide film made of SiO ₂ or a low-k material film is deposited on a conductive layer 1a on a semiconductor substrate 1 on which a semiconductor element is formed. Then, the contact hole 3 and the wiring groove 4 are formed by the lithography / etching technique. A barrier film 5 made of TaN or the like is formed thereon, and a seed layer 7 as a power feeding layer for electrolytic plating is formed thereon by sputtering or CVD.

  Then, by copper plating on the surface of the substrate W, the contact hole 3 and the wiring groove 4 of the semiconductor substrate W are filled with copper and a copper film is formed on the insulating film 2 as shown in FIG. 6 is deposited. Thereafter, the copper film 6, the seed layer 7 and the barrier film 5 on the insulating film 2 are removed by chemical mechanical polishing (CMP), and the surface of the copper film 6 filled in the contact hole 3 and the wiring groove 4 The surface of the insulating film 2 is substantially flush with the surface. Thereby, as shown in FIG. 1C, a wiring made of the copper film 6 is formed inside the insulating film 2.

  In recent years, as the miniaturization and high precision have progressed in the components of all devices, and the manufacturing in the sub-micron region has become common, the influence of the processing method itself on the characteristics of the material has been increasing. Under such circumstances, the machining method in which the tool removes the workpiece while physically destroying it, as in conventional machining, because many defects are generated in the workpiece by machining. As a result, the properties of the workpiece are deteriorated. Therefore, it becomes a problem how the processing can be performed without impairing the characteristics of the material.

  Special processing methods developed as means for solving this problem include chemical polishing, electrolytic processing, and electrolytic polishing. In contrast to conventional physical processing, these processing methods perform removal processing and the like by causing a chemical dissolution reaction. Therefore, defects such as work-affected layers and dislocations due to plastic deformation do not occur, and the problem of performing processing without impairing the properties of the above-described materials is achieved.

  For example, the CMP process generally requires a considerably complicated operation, is complicated in control, and has a considerably long processing time. Furthermore, not only is it necessary to sufficiently perform post-cleaning of the substrate after polishing, but there are also problems such as a large load for draining the slurry and cleaning liquid. For this reason, there has been a strong demand to omit CMP itself or reduce this load. In the future, the interlayer insulating film is also expected to change to a low-k material having a low dielectric constant, and the low-k material has low mechanical strength and cannot withstand stress caused by CMP. Therefore, there is a demand for a process that enables planarization without applying stress to the substrate.

  As a means for solving such a problem, a liquid having a large electric resistance such as pure water or ultrapure water is used as an electrolytic solution, and water molecules in the liquid may be interposed between the electrode and the workpiece as necessary. Electrochemical machining that eliminates mechanical stress on the workpiece and facilitates post-cleaning by arranging an ion exchanger that promotes the dissociation reaction between hydroxide ions and hydrogen ions has been proposed. (For example, refer to Patent Document 1).

  Further, in electrolytic processing (etching) using an electrolytic solution, the surface of the workpiece after processing is flattened by performing etching while keeping the distance between the workpiece and the counter electrode at 10 μm or less, for example, 1 μm. The distance between the platen electrode and the surface of the wafer (substrate) is 1 mm or less, preferably 2000 mm, and a polishing pad (thickness) is provided between the platen electrode and the wafer. There has been proposed an apparatus in which the surface of the wafer is polished by bringing about 200 mm) into contact with the surface of the wafer (see, for example, Patent Document 3).

JP 2003-145354 A JP 2001-102356 A International Publication No. 02/064314 Pamphlet

  An unnecessary portion of a conductive film having an uneven surface formed on the surface of a substrate such as a semiconductor wafer, for example, a copper film 6 embedded in a wiring groove or the like shown in FIG. When removing by the conventional electrolytic processing, a typical problem is that it is difficult to flatten the surface of the conductive film. This is because (1) the distance between the workpiece and the electrode is much larger than the uneven step on the surface of the conductive film formed on the substrate surface, and (2) the electrical resistivity of the electrolyte is small. This is because an appropriate difference in processing speed cannot be obtained in the concave and convex portions on the surface of the conductive film. In particular, when an ion exchanger is disposed between a workpiece such as a substrate and an electrode, electrolytic processing generally proceeds while sliding the ion exchanger along the surface of the workpiece. For this reason, a problem arises in that a defect is generated on the surface of the workpiece or the ion exchanger is worn with the sliding between the ion exchanger and the surface of the workpiece. Therefore, in order to apply electrolytic processing to the removal of a conductive film provided on the surface of a substrate such as a semiconductor wafer, it is required to solve such a problem.

  The present invention has been made in view of the above circumstances, and provides an electrolytic processing apparatus and an electrolytic processing method capable of processing the surface more flat while reducing the occurrence of contamination and defects on the surface of the workpiece as much as possible. The purpose is to do.

  The invention described in claim 1 includes a machining electrode that is freely accessible to a workpiece, a feeding electrode that feeds power to the workpiece, a power source that applies a voltage between the machining electrode and the feeding electrode, and A drive unit that relatively moves the workpiece and at least one of the machining electrode or the power feeding electrode; and a liquid supply unit that supplies liquid between the workpiece and at least one of the machining electrode or the power feeding electrode; A detector for detecting a distance between the workpiece and at least one of the machining electrode or the feeding electrode; and at least one of the workpiece and the machining electrode or the feeding electrode based on a signal from the detector And a control unit that controls the distance to a predetermined value that is 100 μm or less and non-contact with each other.

  Conductive film formed on the surface of a substrate such as a semiconductor wafer by performing processing while controlling the distance between the workpiece and at least one of the processing electrode or the feeding electrode to a predetermined value that is 100 μm or less and non-contacting each other For example, even if there are irregularities with a level difference of about 200 nm on the surface, it is possible to process the irregularities flatly by causing a difference in electrical resistance and a processing speed difference between the concave and convex portions of the irregularity level difference. The distance between the workpiece and at least one of the processing electrode or the feeding electrode is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.

  As a detector for detecting the distance between the workpiece and at least one of the processing electrode or the feeding electrode, for example, an optical (reflection type) or eddy current type distance sensor is used. In the case of providing a so-called end point sensor that detects an end point of electrolytic processing, the end point sensor may be used in combination with the role of this detector. The distance between the workpiece and at least one of the processing electrode or the feeding electrode can be simultaneously measured by a single sensor (endpoint sensor).

  The invention according to claim 2 includes a machining electrode that is freely accessible to a workpiece, a feeding electrode that feeds power to the workpiece, a power source that applies a voltage between the machining electrode and the feeding electrode, and A drive unit that relatively moves the workpiece and at least one of the machining electrode or the power feeding electrode; and a liquid supply unit that supplies liquid between the workpiece and at least one of the machining electrode or the power feeding electrode; An ion exchanger disposed between the workpiece and at least one of the machining electrode or the feeding electrode, a detector for detecting a distance between the workpiece and the ion exchanger, and the detector An electrolytic processing apparatus comprising: a control unit that controls a distance between the workpiece and the ion exchanger to a predetermined value that is 100 μm or less and non-contacting based on a signal from

  Thus, by providing an ion exchanger, the dissociation reaction of water molecules in the liquid into hydroxide ions and hydrogen ions can be promoted. Further, by performing processing while controlling the distance between the workpiece and the ion exchanger to a predetermined value that is 100 μm or less and non-contact with each other, the surface of the conductive film formed on the surface of the substrate such as a semiconductor wafer is formed. For example, even if there are irregularities with a level difference of about 200 nm, the concave and convex portions of this irregularity level difference cause a difference in electrical resistance, and thus a difference in processing speed, thereby flattening the irregularities, and the ion exchanger and workpiece surface By performing electrolytic processing without sliding each other, it is possible to prevent defects on the surface of the workpiece and wear of the ion exchanger. The distance between the workpiece and the ion exchanger is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.

According to a third aspect of the present invention, there is provided a holding portion for floatingly supporting the workpiece so as to be movable in a direction in which it is in contact with or separated from at least one of the processing electrode or the power feeding electrode. It is an electrolytic processing apparatus of description.
Accordingly, the workpiece can be easily moved in a direction in which it is in contact with or separated from at least one of the machining electrode or the feeding electrode, depending on the magnitude of the force applied to the workpiece via the liquid during the electrolytic machining. The distance between the workpiece and at least one of the processing electrode and the feeding electrode can be adjusted.

According to a fourth aspect of the present invention, the control unit is configured such that the pressure of the liquid supplied between the workpiece and at least one of the machining electrode or the feeding electrode, the workpiece and the machining electrode, or the The relative movement speed between at least one of the power supply electrodes or at least one of the voltages applied between the processing electrode and the power supply electrode is controlled. It is an electrolytic processing apparatus of description.
By controlling the relative motion speed between the workpiece and at least one of the processing electrode or the feeding electrode, the liquid force (dynamic pressure) due to the hydroplaning phenomenon generated by this relative motion can be used during the electrolytic processing. The magnitude of the force applied to the workpiece via the liquid can be controlled.

  When electrolytic processing is performed with an electrolytic processing apparatus equipped with an ion exchanger, an adsorption force acts between the workpiece and the ion exchanger, and this adsorption force is a voltage applied between the machining electrode and the feeding electrode. Affected by. For this reason, by controlling the voltage applied between the machining electrode and the feeding electrode, the distance between the workpiece and the ion exchanger can be controlled via the adsorption force acting between the two.

  According to a fifth aspect of the present invention, there is provided a machining electrode that is freely accessible to a workpiece, a feeding electrode that feeds power to the workpiece, a power source that applies a voltage between the machining electrode and the feeding electrode, A drive unit that relatively moves the workpiece and at least one of the machining electrode or the power feeding electrode; and a liquid supply unit that supplies liquid between the workpiece and at least one of the machining electrode or the power feeding electrode; An electrolytic processing apparatus comprising an insulating spacer having a thickness of 100 μm or less disposed between the workpiece and at least one of the processing electrode or the feeding electrode.

  By disposing an insulating spacer having a thickness of 100 μm or less between the workpiece and at least one of the machining electrode or the feeding electrode, the distance between the workpiece and at least one of the machining electrode or the feeding electrode is not in contact with each other. 100 μm or less. The thickness of the insulating spacer is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.

  According to a sixth aspect of the present invention, there is provided a machining electrode that is close to a workpiece, a feeding electrode that feeds power to the workpiece, a power source that applies a voltage between the machining electrode and the feeding electrode, A drive unit that relatively moves the workpiece and at least one of the machining electrode or the power feeding electrode; and a liquid supply unit that supplies liquid between the workpiece and at least one of the machining electrode or the power feeding electrode; The ion exchanger disposed between the workpiece and at least one of the processing electrode or the feeding electrode, and the thickness disposed between the workpiece and the ion exchanger is 100 μm or less. An electrolytic processing apparatus having an insulating spacer.

  By disposing an ion exchanger disposed between the workpiece and at least one of the processing electrode or the feeding electrode and an insulating spacer having a thickness of 100 μm or less between the workpiece and the workpiece, The distance between the workpieces can be set to 100 μm or less without contact with each other.

The invention according to claim 7 is the electrolytic processing apparatus according to claim 5 or 6, wherein the insulating spacer is made of a porous material.
Thereby, the water permeability of an insulating spacer can be ensured and a liquid can distribute | circulate the inside of an insulating spacer.

  According to an eighth aspect of the present invention, in the liquid supply section, a direction or a side in which a liquid jet collides with the workpiece between the workpiece and at least one of the machining electrode or the feeding electrode. The electrolytic processing apparatus according to claim 1, wherein a liquid is supplied from at least one of the two.

The liquid is preferably ultrapure water, pure water, or a liquid having an electric conductivity of 500 μS / em or less.
Ultrapure water is, for example, water having an electric conductivity (1 atm, converted at 25 ° C., the same shall apply hereinafter) of 0.1 μS / cm or less, and pure water is water having an electric conductivity of 10 μS / cm or less. When a liquid with high electrical conductivity is used, the resistance ratio resulting from the distance ratio is the same, but the resistance value of the liquid itself is small. For this reason, for example, the resistance difference between the concave and convex portions in a conductive film with irregularities on the surface Becomes small, and the selectivity of the unevenness is not obtained so much. On the other hand, when ultrapure water or pure water is used, since the resistance difference due to the difference in distance is large, the selectivity of the unevenness is improved. For this reason, it is desirable to use ultrapure water, pure water, or a liquid having an electric conductivity of 500 μS / cm or less as the liquid.

  According to a ninth aspect of the present invention, there is provided a machining electrode that is freely accessible to a workpiece and a feeding electrode that feeds power to the workpiece, and sets a distance between the workpiece and at least one of the machining electrode or the feeding electrode. While maintaining a predetermined value that is 100 μm or less and non-contact with each other, the workpiece and at least one of the processing electrode or the feeding electrode are relatively moved in the presence of a liquid, and between the processing electrode and the feeding electrode. An electrolytic processing method is characterized by applying a voltage.

  According to a tenth aspect of the present invention, at least one of the workpiece and the processing electrode or the feeding electrode is caused by a pressure of a liquid supplied between the workpiece and at least one of the processing electrode or the feeding electrode. 10. The electrolytic processing method according to claim 9, wherein the distance from one side is maintained at a predetermined value which is 100 μm or less and is not in contact with each other.

  According to an eleventh aspect of the present invention, the workpiece, the machining electrode, or the feeding electrode is generated by a pressure of a liquid generated by a relative motion between the workpiece and at least one of the machining electrode or the feeding electrode. 10. The electrolytic processing method according to claim 9, wherein the distance between at least one of the two is maintained at a predetermined value that is 100 μm or less and is not in contact with each other.

  According to a twelfth aspect of the present invention, a machining electrode that is close to the workpiece and a feeding electrode that feeds the workpiece are prepared, and the workpiece and at least one of the machining electrode or the feeding electrode are provided. An ion exchanger is disposed, and the workpiece and at least one of the machining electrode and the feeding electrode are held while maintaining a predetermined distance between the workpiece and the ion exchanger at 100 μm or less and non-contact with each other. Is subjected to relative movement in the presence of a liquid, and a voltage is applied between the machining electrode and the feeding electrode.

  According to a thirteenth aspect of the present invention, the distance between the workpiece and the ion exchanger is 100 μm or less due to the pressure of the liquid existing between the workpiece and at least one of the processing electrode or the feeding electrode. The electrolytic processing method according to claim 12, wherein the predetermined values are not in contact with each other.

According to a fourteenth aspect of the present invention, a distance between the workpiece and the ion exchanger is set to 100 μm by a pressure generated by a relative motion between the workpiece and at least one of the processing electrode or the feeding electrode. The electrolytic processing method according to claim 13, wherein the predetermined values that are not in contact with each other are maintained below.
In the invention described in claim 15, the relative motion is any one of a rotational motion, a translational motion, a linear motion, a scroll motion and a reciprocating motion, or a combination thereof, and the relative motion speed is 0.1 m / s or more. 15. The electrolytic processing method according to claim 11, wherein the electrolytic processing method is any one of the following.
The relative motion speed is preferably 1 m / s or more, and more preferably 2 m / s or more.

  According to a sixteenth aspect of the present invention, there is provided a machining electrode that is freely accessible to a workpiece and a feeding electrode that feeds power to the workpiece, and is provided between the workpiece and at least one of the machining electrode or the feeding electrode. An insulating spacer having a thickness of 100 μm or less is disposed, and the workpiece and at least one of the processing electrode or the feeding electrode are moved relative to each other in contact with the insulating spacer in the presence of a liquid, and the processing electrode and In the electrolytic processing method, a voltage is applied between the power supply electrode.

  According to a seventeenth aspect of the present invention, there is provided a machining electrode that is freely accessible to a workpiece and a feeding electrode that feeds power to the workpiece, and is provided between the workpiece and at least one of the machining electrode or the feeding electrode. An ion exchanger is disposed, and an insulating spacer having a thickness of 100 μm or less is disposed between the workpiece and the ion exchanger in contact with the ion exchanger, and the workpiece and the processing electrode or the power supply are disposed. Electrolytic machining method characterized in that at least one of electrodes is moved relative to each other while being in contact with said insulating spacer and said ion exchanger in the presence of a liquid, and a voltage is applied between said machining electrode and said feeding electrode It is.

The invention according to claim 18 is the electrolytic processing method according to claim 16 or 17, wherein the insulating spacer is made of a porous material.
According to a nineteenth aspect of the present invention, there is provided a liquid from at least one of a direction in which a liquid jet collides with the workpiece or a side between the workpiece and at least one of the machining electrode and the feeding electrode. The electrolytic processing method according to claim 9, wherein the electrolytic processing method is supplied.

  According to the present invention, for example, the surface of a conductive film having unevenness provided on a substrate such as a semiconductor wafer can be processed flat while eliminating the unevenness. In particular, when an ion exchanger is used, the ion exchanger and the workpiece are processed without sliding each other, thereby suppressing generation of defects on the workpiece surface and wear of the ion exchanger. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following explanation, a substrate is used as a workpiece, and a conductive film such as a copper film formed on the surface of the substrate is removed. However, the present invention is not limited to the substrate. Of course, it can be applied.

  FIG. 2 is a plan view showing the configuration of the substrate processing apparatus including the electrolytic processing apparatus according to the embodiment of the present invention. As shown in FIG. 2, this substrate processing apparatus includes, for example, a cassette containing a substrate W having a copper film 6 and a barrier film 5 as conductive films (processed parts) on the surface thereof as shown in FIG. A pair of load / unload units 30 as a loading / unloading unit for loading / unloading, a first cleaning device 31a for performing primary cleaning of the substrate, a second cleaning device 31b for performing secondary cleaning (finish cleaning) of the substrate, A reversing machine 32 for reversing the substrate W and an electrolytic processing apparatus 34 are provided. These devices are arranged in series, and a transfer robot 36 as a transfer device that transfers the substrate W between these devices and transfers is arranged in parallel with these devices. A control unit 38 that controls the electrolytic processing apparatus 34 is disposed adjacent to the load / unload unit 30.

  FIG. 3 is a longitudinal sectional view schematically showing the electrolytic processing apparatus 34. As shown in FIG. 3, the electrolytic processing apparatus 34 has an arm 40 that can move up and down and swings in the horizontal direction, and is suspended from the free end of the arm 40, and the substrate W is placed with its surface facing down (face down). A substrate holding unit 42 that is detachably held, a disk-shaped electrode unit 44 that is disposed below the substrate holding unit 42, and a power source that is connected to the processing electrode 62 and the feeding electrode 64 of the electrode unit 44. 46 is provided.

  The arm 40 is attached to the upper end of the swing shaft 50 connected to the swing motor 48 and swings in the horizontal direction as the swing motor 48 is driven. The swing shaft 50 is connected to a ball screw 52 extending in the vertical direction, and moves up and down together with the arm 40 as the vertical movement motor 54 connected to the ball screw 52 is driven.

  The substrate holding unit 42 is connected to a rotation motor 56 as a first drive unit that relatively moves the substrate W held by the substrate holding unit 42 and the electrode unit 44. As the rotation motor 56 is driven, the substrate holding unit 42 is connected. Rotates (spins). Further, as described above, the arm 40 can move up and down and swing in the horizontal direction, and the substrate holder 42 moves up and down and swings in the horizontal direction integrally with the arm 40. The electrode unit 44 is connected to a hollow motor 60 as a second drive unit that moves the substrate W and the electrode unit 44 relative to each other. A revolving motion that does not rotate as the hollow motor 60 is driven is a so-called scroll. Perform motion (translational rotation). Of course, as the hollow motor 60 is driven, the electrode portion 44 may perform a rotation (autorotation) movement with the position centered from the rotation center of the substrate holding portion 42 as the rotation center. .

  In the electrode portion 44, for example, a plurality of fan-shaped machining electrodes 62 and power supply electrodes 64 are alternately embedded with their surfaces (upper surfaces) exposed. In this example, the surface (upper surface) of the electrode portion 44, the processing electrode 62, and the power supply electrode 64 is flush. The processing electrode 62 is connected to the cathode of the power source 46, and the power supply electrode 64 is connected to the anode of the power source 46.

  In this embodiment, for example, when processing copper, an electrolytic processing action occurs on the cathode side, so that the electrode connected to the cathode of the power supply 46 becomes the processing electrode 62 and the electrode connected to the anode of the power supply 46 feeds power. The processed electrode 62 and the feeding electrode 64 are alternately arranged along the circumferential direction. Depending on the processing material, the electrode connected to the cathode of the power supply 46 may be used as a feeding electrode, and the electrode connected to the anode may be used as a processing electrode. That is, when the material to be processed is, for example, copper, molybdenum, or iron, an electrolytic processing action occurs on the cathode side. Therefore, the electrode connected to the cathode of the power supply 46 becomes the processing electrode 62, and the electrode connected to the anode supplies power. It becomes the electrode 64. On the other hand, when the material to be processed is, for example, aluminum or silicon, an electrolytic processing action occurs on the anode side. Therefore, the electrode connected to the anode of the power supply 46 becomes the processing electrode, and the electrode connected to the cathode becomes the power supply electrode.

  In the case where the processed part is a conductive oxide such as tin oxide or indium tin oxide (ITO), electrolytic processing is performed after the processed part is reduced. That is, in FIG. 3, the conductive oxide is reduced such that the electrode connected to the anode of the power source 46 serves as a reduction electrode and the electrode connected to the cathode serves as a power supply electrode. Subsequently, the reduced conductive oxide is processed using the electrode that was previously the power supply electrode as the processing electrode. Alternatively, the reduction electrode may be a processed electrode by reversing the polarity when the conductive oxide is reduced. Also, the conductive oxide can be removed by using the workpiece as a cathode and facing the anode electrode.

  In this example, the copper film 6 or the barrier film 5 as the conductive film formed on the surface of the substrate is subjected to electrolytic processing. However, an unnecessary ruthenium (Ru) film formed or adhered to the surface of the substrate. In the same manner, that is, electrolytic processing (etching removal) can be performed using a ruthenium film as an anode and an electrode connected to the cathode as a processing electrode.

  Thus, by providing the processing electrode 62 and the power supply electrode 64 alternately along the circumferential direction, it is not necessary to provide a power supply unit that supplies power to the conductive film (processed part) of the substrate W. The entire surface can be processed. Further, as a method for applying voltage and current, in addition to DC input, rectangular wave, pulse, or sine wave input may be used. In the case of rectangular wave input, the voltage and current inputs are rectangular waves of positive and negative and positive and zero, and the duty ratio is arbitrarily set depending on the object to be processed.

  Here, oxidation or elution of the processing electrode 62 and the feeding electrode 64 generally causes a problem due to an electrolytic reaction. For this reason, it is preferable to use carbon, a comparatively inactive noble metal, a conductive oxide, or a conductive ceramic rather than the metal and metal compound which are widely used for an electrode as a raw material of an electrode. As an electrode made of this noble metal, for example, titanium is used as the base electrode material, platinum or iridium is attached to the surface by plating or coating, and sintering is performed at a high temperature to maintain stability and strength. Can be mentioned. Ceramic products are generally obtained by heat treatment using inorganic materials as raw materials, and products having various characteristics are made using various nonmetals, metal oxides, carbides and nitrides as raw materials. Some of these are conductive ceramics. When the electrode is oxidized, the electrical resistance value of the electrode increases, leading to an increase in applied voltage. Thus, by protecting the electrode surface with a material that is difficult to oxidize such as platinum or a conductive oxide such as iridium, the electrode is protected. A decrease in conductivity due to oxidation of the material can be prevented.

  A liquid supply hole 44b that communicates with a liquid channel 44a provided inside the electrode unit 44 is provided at a position surrounding the processing electrode 62 and the power supply electrode 64 of the electrode unit 44. The liquid channel 44a is a liquid such as a pump. It extends from a liquid supply source 66 having a pressurizing part, and is connected to a liquid supply pipe 68 that penetrates the inside of the hollow part of the hollow motor 60. As a result, the liquid supplied from the liquid supply source 66 at a predetermined pressure, preferably pure water, more preferably ultrapure water, is allowed to pass through the liquid supply pipe 68 and the liquid flow path 44a and upward from the liquid supply hole 44b. A liquid supply unit is configured to be ejected toward the substrate and supply the liquid to the substrate W held by the substrate holding unit 42 on the upper surface of the electrode unit 44. In addition, when supplying the machining fluid in the present invention from a supply hole provided between a plurality of electrodes as shown in the drawing, or when supplying from a supply hole provided in the electrode itself, the processing liquid is supplied from outside the electrode portion. There are cases.

  The substrate holding part 42 has a cylindrical housing 70 that opens downward, and a disk-shaped chucking plate 72 that detachably holds the substrate W by suction or the like. The chucking plate 72 is housed in the housing 70 so that when the substrate W is held on the lower surface, the lower surface of the substrate W is positioned below a plane formed by the lower surface of the housing 70. A claw portion 70a that protrudes inward is provided at the lower end of the housing 70, and a large-diameter flange portion 72a is provided at the upper portion of the chucking plate 72. The flange portion 72a is engaged with the claw portion 70a. Thus, the escape of the chucking plate 72 from the housing 70 is prevented.

  The other end of an elastic body 74 made of a conical rubber or the like having one end hermetically fixed to the inner peripheral surface of the housing 70 is hermetically fixed to the peripheral edge of the upper surface of the chucking plate 72. An air chamber 76 surrounded by the chucking plate 72 and the elastic body 74 is defined. An air introduction hole 70 b for introducing air into the air chamber 76 is provided in the ceiling wall of the housing 70. As a result, the chucking plate 72 is pressed downward by the air pressure introduced into the air chamber 76, and in this state, a floating force that causes the substrate W to float upward acts on the substrate W held by the chucking plate 72. When the levitation force becomes larger than the pressing force for pressing the chucking plate 72 downward, the flange portion 72a of the chucking plate 72 is released from the claw portion 70a of the housing 70, and the chucking plate 72 is in a floating state. . Moreover, the floating position of the chucking plate 72 moves up and down according to the magnitude of the floating force that causes the substrate W to float upward.

  A distance S between the surface (lower surface) of the substrate W held by the substrate holding unit 42 and the surfaces (upper surface) of the processing electrode 62 and the feeding electrode 64 embedded in the electrode unit 44 is detected. A detector 80 is provided. As the detector 80, for example, an optical (reflective) distance sensor that receives a laser beam reflected on the surface of the substrate W and detects the distance to the substrate W, or a surface (conductive film) of the substrate W is used. An eddy current type distance sensor that detects the distance from the substrate W by generating an eddy current is used.

  In addition, when a so-called end point sensor for detecting an end point at the time of electrolytic processing is provided, the end point sensor may be used in combination with the role of the detector 80. In this case, the film thickness of the conductive film and the distance S between the lower surface of the substrate W held by the substrate holder 42 and the upper surfaces of the processing electrode 62 and the feeding electrode 64 are simultaneously measured by a single sensor (endpoint sensor). It can be measured.

  The output from the detector 80 is input to the control unit 38. The output from the control unit 38 is input to the liquid supply source 66, and the liquid pressurizing unit such as a pump of the liquid supply source 66 is feedback-controlled. In this example, during the electrolytic processing, the processing electrode 62 and the feeding electrode 64 are adjusted by adjusting the pressure of the liquid supplied from the liquid supply source 66 between the electrode unit 44 and the substrate W held by the substrate holding unit 42. The distance S between the upper surface of the substrate and the substrate W held by the substrate holding unit 42 is set to a predetermined value of 100 μm or less without contact with each other. This distance S is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.

  That is, the lower surface of the substrate W, the processing electrode 62, and the feeding electrode are performed while performing electrolytic processing while supplying a liquid having a predetermined pressure between the electrode portion 44 and the substrate W held by the chucking plate 72 of the substrate holding portion 42. The distance S from the upper surface of 64 is detected by the detector 80. When the distance S is smaller than a predetermined value of 1 μm or less, for example, the pressure of the liquid supplied from the liquid supply source 66 is increased to raise the floating position of the chucking plate 72. Then, the pressure of the liquid supplied from the liquid supply source 66 is decreased, and the floating position of the chucking plate 72 is lowered. Thus, during the electrolytic processing, the distance S between the lower surface of the substrate W and the upper surfaces of the processing electrode 62 and the feeding electrode 64 is always set to a predetermined value of 1 μm or less, for example.

  Next, substrate processing (electrolytic processing) using this substrate processing apparatus will be described. First, for example, as shown in FIG. 1B, a cassette containing a substrate W on which a copper film 6 and a seed layer 7 are formed as a conductive film (processed part) on the surface is set in a load / unload unit 30. Then, one substrate W is taken out from the cassette by the transfer robot 36. The transport robot 36 transports the taken-out substrate W to the reversing machine 32 as necessary, and reverses the substrate W so that the surface on which the conductive film (copper film 6) is formed faces downward.

  The transfer robot 36 receives the inverted substrate W, transfers it to the electrolytic processing apparatus 34, and holds it by the chucking plate 72 of the substrate holder 42. At this time, air of a predetermined pressure is introduced and sealed in the air chamber 76 of the substrate holding part 42, thereby pressing the chucking plate 72 downward with a predetermined pressure. In this state, the arm 40 is moved to move the substrate holding portion 42 holding the substrate W to a processing position directly above the electrode portion 44. Next, the vertical movement motor 54 is driven to lower the substrate holding portion 42, and the substrate W held by the chucking plate 72 is brought into contact with or close to the surfaces of the processing electrode 62 and the feeding electrode 64.

  Next, a liquid having a predetermined pressure is supplied from the liquid supply source 66 between the electrode portion 44 and the substrate W. At this time, the liquid is ejected from the liquid supply hole 44b toward the substrate W, and the liquid pressure acts on the substrate W. While floating the chucking plate 72, the distance S between the substrate W and the processing electrode 62 and the feeding electrode 64 is detected by the detector 80, and the liquid supply source is set so that the distance S becomes a predetermined value of, for example, 1 μm or less. The pressure of the liquid supplied from 66 is adjusted.

  In a state where the distance S between the substrate W and the processing electrode 62 and the feeding electrode 64 is set to a predetermined value of, for example, 1 μm or less, the rotation motor 56 is driven as necessary to rotate the substrate W, and at the same time, the hollow motor 60 , And the electrode portion 44 is scrolled to move the substrate W held by the substrate holding portion 42 relative to the processing electrode 62 and the feeding electrode 64, and at the same time, the processing electrode 62 and the feeding electrode 64 are A predetermined voltage is applied during the period. Thus, electrolytic processing of the conductive film (copper film 6) on the surface of the substrate W is performed at the processing electrode (cathode) 62 by hydroxide ions or hydrogen ions generated by dissociation of water molecules in the liquid. During the electrolytic processing, the distance S between the lower surface of the substrate W and the upper surfaces of the processing electrode 62 and the feeding electrode 64 is detected by the detector 80, and the liquid supply is performed so that the distance S is always a predetermined value of 1 μm or less, for example. The pressure of the liquid supplied from the source 66 is adjusted.

Here, as shown in FIG. 4, the substrate W held by the substrate holder 42 is processed as much as possible until the distance S from the processing electrode 62 is 10 μm or less, preferably several μm to several hundreds nm. It is preferable to perform electrolytic processing in a state where the electrode 62 is not in contact with the electrode 62 in order to eliminate a step on the surface of the conductive film such as the copper film 6 (see FIG. 1B) on the surface of the substrate W. . That is, for example, the surface of the copper film 6 as a conductive film formed on the surface of the substrate W such as a semiconductor wafer shown in FIG. 1B is usually on the order of several hundreds nm, as shown in FIG. There is an uneven step T. For this reason, for example, if the distance S between the surface of the copper film 6 and the processing electrode 62 is about 1 mm, for example, it becomes extremely large with respect to the uneven step T, and the electrical resistance is proportional to the distance. The distance R ₁ from the bottom of the concave portion of the surface to the processing electrode 62 and the distance R ₂ from the top of the convex portion to the processing electrode 62 become substantially the same, and only the convex portion of the copper film 6 is preferentially removed. It becomes difficult. However, when the distance S between the surface of the copper film 6 and the processing electrode 62 is 1 μm, for example, it becomes smaller with respect to the uneven step T, and the tip of the convex portion of the copper film 6 is processed preferentially. With the increase, the remaining step can be made smaller and the surface of the copper film 6 can be processed more flatly.

  In FIG. 5, the distance S between the workpiece (substrate) and the electrode (working electrode) was changed to 50 μm, 10 μm, 1 μm, and 1 mm, and electrolytic processing (polishing) was performed using ultrapure water as a liquid. The relationship between the residual level difference and the processing amount is shown. From FIG. 5, when the distance S between the workpiece (substrate) and the electrode (working electrode) is 1 mm, the initial unevenness is hardly eliminated. By setting the distance S to 50 μm, the initial unevenness is eliminated. When this distance S is set to 1 μm, it can be seen that it approaches an ideal straight line.

  In general, the initial unevenness step on the surface of a copper film formed on a substrate such as a semiconductor wafer in order to form a copper wiring is often around 200 nm. From the above considerations and experiments, the surface of the copper film 6 The distance S between the processing electrode 62 is generally about 100 μm, preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.

  At this time, the voltage applied between the machining electrode 62 and the feeding electrode 64 or the current flowing between them is monitored by the control unit 38 to detect the end point (machining end point). That is, if electrolytic processing is performed in the state where the same voltage (current) is applied, a difference occurs in the current (applied voltage) flowing depending on the material. For example, as shown in FIG. 6A, when the current flowing when the surface of the substrate W on which the material B and the material A are sequentially formed is subjected to electrolytic processing is monitored, the material A is electrolytically processed. A constant current flows while the material B is in operation, but the current that flows at the time of transition to processing of a different material B changes. Similarly, even when the voltage is applied between the machining electrode 62 and the feeding electrode 64, a constant voltage is applied while the material A is electrolytically processed as shown in FIG. 6B. However, the voltage applied at the time of shifting to processing of a different material B changes. 6A shows a case where the current is less likely to flow when the material B is electrolytically processed than when the material A is electrolytically processed. FIG. 6B shows the case where the material B is electrolytically processed. The example shows the case where the voltage is higher than when the material A is electrolytically processed. Thus, the end point can be reliably detected by monitoring the change in the current or voltage.

  In this example, the control unit 38 shows an example in which the voltage applied between the machining electrode 62 and the feeding electrode 64 or the current flowing between them is monitored to detect the machining end point. The control unit 38 may monitor a change in the state of the substrate being processed and detect an arbitrarily set processing end point. In this case, the processing end point indicates a point in time when a desired processing amount is reached or a parameter corresponding to the processing amount reaches an amount corresponding to a desired processing amount for a specified portion of the processing surface. . As described above, even during the machining, the machining end point can be arbitrarily set and detected so that the electrolytic machining can be performed in a multistage process.

  For example, detecting changes in frictional force due to differences in the coefficient of friction that occurs when the substrate reaches a different material, or changes in frictional force resulting from removing irregularities when flattening irregularities on the surface of the substrate It is also possible to determine the processing amount and detect the processing end point. In addition, heat generated due to electrical resistance of the work surface and heat generated by collision of ions and water molecules moving in the liquid (pure water) between the work surface and the work surface occurred, for example, deposited on the surface of the substrate. When electrolytic polishing of a copper film is performed with constant voltage control, as the electrolytic processing proceeds and the barrier film and insulating film are exposed, the electrical resistance increases, the current value decreases, and the amount of heat generation decreases sequentially. Therefore, the processing amount may be determined by detecting the change in the heat generation amount, and the processing end point may be detected. Alternatively, it is also possible to detect a change in the intensity of reflected light due to a difference in reflectance that occurs when a different material is reached, detect the film thickness of the film to be processed on the substrate, and thereby detect the processing end point.

  In addition, an eddy current is generated inside a conductive film such as a copper film, and the eddy current flowing inside the substrate is monitored. For example, a change in frequency or impedance is detected, and the film thickness of the film to be processed on the substrate is determined. It may be detected to detect the processing end point. Further, in the electrolytic machining, the machining rate is determined by the current value flowing between the machining electrode and the feeding electrode, and the machining amount is proportional to the amount of electricity obtained by the product of the current value and the machining time. Therefore, the machining end point may be detected by integrating the amount of electricity obtained by the product of the current value and the machining time, determining that the accumulated value has reached a predetermined value, and determining the machining end point.

  After the electrolytic processing is completed, the power supply 46 is disconnected from the processing electrode 62 and the power supply electrode 64, the rotation of the substrate holding portion 42 and the electrode portion 44 is stopped, and the liquid between the electrode portion 44 and the substrate W is further stopped. Stop supplying. Thereafter, the substrate holder 42 is raised, the arm 40 is moved, and the substrate W is delivered to the transport robot 36. The transport robot 36 that has received the substrate W transports it to the reversing machine 32 and reverses it as necessary, transports it to the first cleaning machine 31a, transports the substrate to the second cleaning machine 31b, and transports it to the second cleaning machine 31b. The secondary cleaning (finish cleaning) is sequentially performed and dried, and the dried substrate W is returned to the cassette of the load / unload unit 30.

  Here, if the liquid supplied between the substrate W and the electrode portion 44 during the electrolytic processing has a high electrical conductivity, although the resistance ratio resulting from the distance ratio is the same, the resistance value itself is small. Become. For this reason, the difference in resistance due to the difference in distance is reduced, and for example, it becomes difficult to process the surface of the conductive film having irregularities flatly while eliminating the irregularities. For this reason, it is preferable to use pure water or ultrapure water as the liquid. Pure water is, for example, water having an electric conductivity of 10 μS / cm or less, and ultrapure water is, for example, water having an electric conductivity of 0.1 μS / cm or less. By performing electrolytic processing using pure water or ultrapure water that does not contain an electrolyte in this way, it is possible to prevent the impurities such as the electrolyte from adhering to or remaining on the surface of the substrate W. . In addition, by using pure water or ultrapure water with low electrical conductivity as the liquid, the resistance difference due to the difference in distance is increased, for example, while removing the unevenness on the surface of the conductive film having unevenness. It can be processed flat.

Instead of pure water or ultrapure water, a liquid having an electric conductivity of 500 μS / cm or less, for example, an electrolytic solution obtained by adding an electrolyte to pure water or ultrapure water may be used. By using the electrolytic solution, electric resistance can be reduced and power consumption can be reduced. As this electrolytic solution, for example, a neutral salt such as NaCl or Na ₂ SO ₄ , an acid such as HCl or H ₂ SO ₄ , or an alkali such as ammonia can be used. Depending on the characteristics, it can be appropriately selected and used.

  Furthermore, instead of pure water or ultrapure water, a surfactant or the like is added to pure water or ultrapure water, and the electric conductivity is 500 μS / cm or less, preferably 50 μS / cm or less, more preferably 0. A liquid having a specific resistance of 10 MΩ · cm or less may be used. In this way, by adding a surfactant to pure water or ultrapure water, a layer having a uniform suppressing action for preventing the movement of ions is formed at the interface between the substrate W and the processing electrode 62. The flatness of the work surface can be improved by reducing the concentration of exchange (dissolution of metal). Here, the surfactant concentration is preferably 100 ppm or less.

  FIG. 7 shows an electrolytic processing apparatus 34a according to another embodiment of the present invention. The electrolytic processing apparatus 34a shown in FIG. 7 differs from the electrolytic processing apparatus 34 shown in FIG. 4 as follows. That is, the electrolytic processing apparatus 34a shown in FIG. 7 is disposed above the electrode unit 44 as a liquid supply unit, and between the electrode unit 44 and the substrate W held by the substrate holding unit 42 from the side of the substrate holding unit 42. A device provided with a liquid supply nozzle 82 for supplying a liquid is used. Then, a signal input from the detector 80 to the control unit 38 is fed back to the rotation motor 56 and the hollow motor 60 to control the rotation speed of the rotation motor 56 and the hollow motor 60. The relative movement speed of the held substrate W and the processing electrode 62 and the feeding electrode 64 embedded in the electrode portion 44 is adjusted. Only one of the rotational speeds of the rotation motor 56 and the hollow motor 60 may be controlled.

  In this example, the relative movement between the electrode unit 44 and the substrate W held by the substrate holding unit 42 is caused by a liquid force (dynamic pressure) due to a hydroplaning phenomenon generated in the liquid existing therebetween, that is, the electrode By changing the relative motion speed between the portion 44 and the substrate W held by the substrate holding portion 42, the magnitude of the force applied to the substrate W via the liquid during the electrolytic processing is adjusted.

  That is, while the liquid is supplied from the liquid supply nozzle (liquid supply unit) 82 between the electrode unit 44 and the substrate W held by the chucking plate 72 of the substrate holding unit 42, the two are moved relative to each other to perform electrolytic processing. The distance S between the lower surface of the substrate W and the upper surfaces of the processing electrode 62 and the feeding electrode 64 is detected by the detector 80. When the distance S is smaller than a predetermined value of, for example, 1 μm or less, the relative movement speed between the electrode portion 44 and the substrate W is increased to raise the floating position of the chucking plate 72. Then, the relative movement speed between the electrode portion 44 and the substrate W is decreased, and the floating position of the chucking plate 72 is lowered. Thus, during the electrolytic processing, the distance S between the lower surface of the substrate W and the upper surfaces of the processing electrode 62 and the feeding electrode 64 is always set to a predetermined value of 1 μm or less, for example.

  In this example, as described above, the substrate W held by the chucking plate 72 is brought into contact with or close to the surfaces of the processing electrode 62 and the power supply electrode 64. At this time, supply of liquid from the liquid supply nozzle (liquid supply unit) 82 between the electrode unit 44 and the substrate W is started. Then, the rotation motor 56 and the hollow motor 60 are rotated to move the electrode unit 44 and the substrate W relative to each other, and the chucking plate 72 is floated by the liquid pressure (dynamic pressure) acting on the substrate W at this time. The distance S between W and the machining electrode 62 and the feeding electrode 64 is detected by the detector 80, and the rotational speeds of the rotation motor 56 and the hollow motor 60 are adjusted so that the distance S becomes a predetermined value of, for example, 1 μm or less. To do.

  A predetermined voltage is applied between the processing electrode 62 and the power supply electrode 64 by the power supply 46 in a state where the distance S between the substrate W and the processing electrode 62 and the power supply electrode 64 is set to a predetermined value of, for example, 1 μm or less. Thus, electrolytic processing of the conductive film (copper film 6) on the surface of the substrate W is performed at the processing electrode (cathode) 62 by hydroxide ions or hydrogen ions generated by dissociation of water molecules in the liquid. During the electrolytic processing, a distance S between the lower surface of the substrate W and the upper surfaces of the processing electrode 62 and the feeding electrode 64 is detected by the detector 80, and the rotation is performed so that the distance S is always a predetermined value of, for example, 1 μm or less. The rotational speeds of the motor 56 and the hollow motor 60 are adjusted.

  The relative motion speed between the substrate W and the processing electrode 62 and the feeding electrode 64 is generally 0.1 m / s or more, preferably 1 m / s or more, and more preferably 2 m / s or more. .

  FIG. 8 shows an electrolytic processing apparatus 34b according to still another embodiment of the present invention. The electrolytic processing apparatus 34b shown in FIG. 8 is different from the electrolytic processing apparatus 34 shown in FIG. 3 in that a membrane-like ion exchanger 84 that integrally covers the surface of the electrode portion 44 and the surfaces of the processing electrode 62 and the feeding electrode 64. , And the distance S between the surface (upper surface) of the ion exchanger 84 and the surface (lower surface) of the substrate W is detected by the detector 80, and the distance S between the ion exchanger 84 and the substrate W is detected. It is in the point which adjusted it. A through hole is provided at a position corresponding to each liquid supply hole 44b of the ion exchanger 84 so that the flow of liquid ejected from each liquid supply hole 44b directly hits the substrate W.

Thus, by positioning the ion exchanger 84 between the substrate W and the processing electrode 62 and the power supply electrode 64, the processing speed can be greatly improved. That is, ultrapure water electrochemical processing using ultrapure water as a liquid is due to chemical interaction between hydroxide ions in the ultrapure water and the material to be processed. However, since the hydroxide ion concentration, which is a reactive species contained in ultrapure water, is as small as 10 ⁻⁷ mol / L at room temperature and pressure, reactions other than removal processing reactions (oxide film formation, etc.) It is conceivable that the removal processing efficiency is reduced by the above. For this reason, in order to perform the removal processing reaction with high efficiency, it is necessary to increase the hydroxide ions. Thus, as a method of increasing hydroxide ions, there is a method of promoting the dissociation reaction of ultrapure water with a catalyst material, and an ion exchanger is an effective catalyst material. Specifically, the activation energy related to the dissociation reaction of water molecules is reduced by the interaction between the functional groups in the ion exchanger and the water molecules. Thereby, dissociation of water is promoted, and the processing speed can be improved.

  Here, it is more preferable to use an ion exchanger 84 having excellent water permeability. By flowing pure water or ultrapure water so as to pass through the ion exchanger 84, sufficient water is supplied to the functional group (sulfonic acid group in the case of a strongly acidic cation exchange material) that promotes the dissociation reaction of water. Thus, the amount of dissociation of water molecules can be increased, and the processing products (including gas) generated by the reaction with hydroxide ions (or OH radicals) can be removed by the flow of water to increase the processing efficiency.

  The ion exchanger 84 can be composed of, for example, a nonwoven fabric provided with an anion exchange group or a cation exchange group. The cation exchange group preferably has a strong acidic cation exchange group (sulfonic acid group), but may have a weak acidic cation exchange group (carboxyl group). The anion exchange group preferably has a strong basic anion exchange group (quaternary ammonium group), but may have a weak basic anion exchange group (tertiary or lower amino group).

  Here, for example, a nonwoven fabric provided with a strong base anion exchange group is produced by a so-called radiation graft polymerization method in which a polyolefin nonwoven fabric having a fiber diameter of 20 to 50 μm and a porosity of about 90% is irradiated with γ rays and then graft polymerization is performed. The graft chain is introduced, and then the introduced graft chain is aminated to introduce a quaternary ammonium group. The capacity of the ion exchange group to be introduced is determined by the amount of graft chains to be introduced. In order to perform the graft polymerization, for example, using monomers such as acrylic acid, styrene, glycidyl methacrylate, sodium styrenesulfonate, chloromethylstyrene, and the like, by controlling the monomer concentration, reaction temperature, and reaction time, The amount of grafting to be polymerized can be controlled. Therefore, the ratio of the weight after graft polymerization to the weight of the material before graft polymerization is called the graft ratio. This graft ratio can be up to 500%, and the ion exchange groups introduced after the graft polymerization are A maximum of 5 meq / g is possible.

  The nonwoven fabric provided with the strongly acidic cation exchange group was irradiated with γ-rays on a polyolefin nonwoven fabric having a fiber diameter of 20 to 50 μm and a porosity of about 90% in the same manner as the method of providing the strongly basic anion exchange group. The graft chain is introduced by a so-called radiation graft polymerization method in which post-graft polymerization is performed, and then the introduced graft chain is treated with, for example, heated sulfuric acid to introduce a sulfonic acid group. Moreover, a phosphoric acid group can be introduce | transduced if it processes with the heated phosphoric acid. Here, the graft ratio can be 500% at the maximum, and the ion exchange group introduced after the graft polymerization can be 5 meq / g at the maximum.

  Examples of the material of the ion exchanger 84 include polyolefin polymers such as polyethylene and polypropylene, and organic polymers such as polyurethane. Moreover, as a raw material form, a woven fabric, a sheet | seat, a porous material, a short fiber, etc. other than a nonwoven fabric are mentioned. Here, polyethylene and polypropylene can be subjected to graft polymerization by generating radicals in the material by first irradiating the material with radiation (γ rays and electron beams) (pre-irradiation) and then reacting with the monomer. . Thereby, a graft chain having high uniformity and few impurities can be formed. On the other hand, other organic polymers can be radically polymerized by impregnating the monomer and irradiating (simultaneously irradiating) radiation (γ rays, electron beams, ultraviolet rays). In this case, it is not uniform, but can be applied to most materials.

  As described above, the ion exchanger 84 is composed of a nonwoven fabric provided with an anion exchange group or a cation exchange group, so that liquid such as pure water, ultrapure water, or an electrolytic solution can freely move inside the nonwoven fabric, and the nonwoven fabric. It becomes possible to easily reach an active site having an internal water decomposition catalytic action, and many water molecules are dissociated into hydrogen ions and hydroxide ions. Furthermore, since the hydroxide ions generated by the dissociation are efficiently carried with the movement of liquid such as pure water, ultrapure water, or electrolytic solution, a high current can be obtained even at a low applied voltage.

  Here, when the ion exchanger 84 is composed only of an anion exchange group or a cation exchange group, not only the work material that can be electrolytically processed but also the impurities are likely to be generated depending on the polarity. Therefore, an anion exchanger having an anion exchange group and a cation exchanger having a cation exchange group are overlapped, or both the anion exchange group and the cation exchange group are added to the ion exchange group itself. As a result, the range of the material to be processed can be expanded, and impurities can be hardly generated.

  In this example, the ion exchanger 84 is adjusted by adjusting the pressure of the liquid supplied between the electrode part 44 and the substrate W held by the substrate holding part 42 from the liquid supply source 66 during the electrolytic processing. The distance S between the upper surface of the substrate and the substrate W held by the substrate holding unit 42 is set to a predetermined value of 100 μm or less without contact with each other. This distance S is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.

  As a result, even if the surface of the conductive film formed on the surface of a substrate such as a semiconductor wafer has unevenness with a level difference of about 200 nm, for example, there is a difference in electrical resistance between the concave and convex portions of the unevenness level and thus the processing speed. By producing a difference to flatten the unevenness and performing electrolytic processing without sliding the ion exchanger 84 and the surface of the substrate W with each other, defects occur on the surface of the substrate W, or the ion exchanger 84. Can be prevented from wearing out.

  FIG. 9 shows an electrolytic processing apparatus 34c according to another embodiment of the present invention. The electrolytic processing apparatus 34c shown in FIG. 9 is different from the electrolytic processing apparatus 34a shown in FIG. 7 in that a membrane-like ion exchanger 84 that integrally covers the surface of the processing electrode 62 and the feeding electrode 64 on the surface of the electrode portion 44. , And the distance S between the surface (upper surface) of the ion exchanger 84 and the surface (lower surface) of the substrate W is detected by the detector 80, and the distance S between the ion exchanger 84 and the substrate W is detected. It is in the point which adjusted it.

  In other words, in this example, during the electrolytic processing, the rotational speed of at least one of the motor 56 for rotation and the hollow motor 60 is adjusted, and the substrate W held by the substrate holding portion 42 and the processing electrode embedded in the electrode portion 44. The distance S between the upper surface of the ion exchanger 84 and the substrate W held by the substrate holding part 42 is adjusted to be a predetermined value of 100 μm or less without contact with each other by adjusting the relative speed of movement between the electrode 62 and the power supply electrode 64. To. This distance S is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.

When the ion exchanger 84 is placed between the substrate W and the processing electrode 62 and the power supply electrode 64 and the electrolytic processing is performed as in the example shown in FIGS. An attracting force acts on this, and this attracting force is affected by a voltage applied between the machining electrode 62 and the feeding electrode 64. Therefore, the pressure of the liquid supplied between the electrode unit 44 and the substrate W held by the substrate holding unit 42 from the liquid supply source 66 is adjusted, or the substrate W and the electrode unit 44 held by the substrate holding unit 42 are adjusted. By controlling the voltage applied between the processing electrode 62 and the power supply electrode 64 instead of adjusting the relative movement speed between the embedded processing electrode 62 and the power supply electrode 64 or using them together. The distance S between the upper surface of the ion exchanger 84 and the substrate W held by the substrate holding part 42 may be a predetermined value of 100 μm or less without contact with each other. This distance S is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.
The distance between the workpiece and the ion exchanger can be controlled.

  In each of the above examples, the distance S between the substrate W and the processing electrode 62 and the feeding electrode 64 or the distance S between the substrate W and the ion exchanger 84 covering the surface of the processing electrode 62 and the feeding electrode 64 is detected. Although detection is performed at 80, a detector may be made unnecessary by creating a calibration curve in advance. In this case, the distance between the substrate and the processing electrode and the power supply electrode, or the distance between the substrate and the ion exchanger is determined based on the liquid pressure acting on the substrate or the dynamic pressure generated in the liquid by relative movement, and the weight of the substrate and the substrate holder. Is subtracted, and if necessary, the adsorption force acting between the substrate W and the ion exchanger is further subtracted.

  FIG. 10 shows an electrolytic processing apparatus 34d according to still another embodiment of the present invention. The electrolytic processing apparatus 34d of this embodiment is different from the electrolytic processing apparatus 34a shown in FIG. 7 in that the substrate W is directly adsorbed on its lower surface without using a chucking plate or the like as the substrate holding part 42. In addition, an insulating spacer 86 having a thickness t of 100 μm or less is provided on the surface of the electrode portion 44 so as to integrally cover the processing electrode 62 and the power feeding electrode 64, thereby rotating the motor. 56 and the rotational speed of the hollow motor 60 are not controlled. The thickness t of the insulating spacer 86 is preferably 50 μm or less, more preferably 10 μm or less, and even more preferably 1 μm or less.

  In this example, in a state where the surface (lower surface) of the substrate W held by the substrate holding unit 42 is always in contact with the surface (upper surface) of the insulating spacer 86, a liquid is supplied between the electrode unit 44 and the substrate W. While supplying, the motor 56 for rotation and the hollow motor 60 are driven to move the substrate W, the machining electrode 62 and the feeding electrode relative to each other, and a voltage is applied between the machining electrode 62 and the feeding electrode 64 to perform electrolytic machining. I do. Thus, the distance S between the substrate W and the processing electrode 62 and the power feeding electrode 64 is always equal to the thickness t of the insulating spacer 86 without controlling the rotational speed of the motor 56 for rotation and the hollow motor 60 (t = S), 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less, and further 1 μm or less.

  Thus, by setting the distance S between the substrate W and the processing electrode 62 and the feeding electrode 64 to 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less, and further 1 μm or less, for example, on a substrate such as a semiconductor wafer. The surface of the provided conductive film having unevenness can be processed flat while eliminating the unevenness.

  The insulating spacer 86 is preferably made of a porous material, thereby ensuring water permeability of the insulating spacer 86 and allowing liquid such as ultrapure water or pure water to flow inside the insulating spacer 86. Can do.

  FIG. 11 shows an electrolytic processing apparatus 34e according to still another embodiment of the present invention. The electrolytic processing apparatus 34e of this embodiment is different from the electrolytic processing apparatus 34d shown in FIG. 10 in that an ion exchanger 84 that integrally covers the processing electrode 62 and the power supply electrode 64 is attached to the surface of the electrode portion 44. The insulating spacer 86 is attached to the surface (upper surface) of the exchanger 84.

  In this example, in a state where the surface (lower surface) of the substrate W held by the substrate holding unit 42 is always in contact with the surface (upper surface) of the insulating spacer 86, a liquid is supplied between the electrode unit 44 and the substrate W. While supplying, the motor 56 for rotation and the hollow motor 60 are driven to move the substrate W, the machining electrode 62 and the feeding electrode relative to each other, and a voltage is applied between the machining electrode 62 and the feeding electrode 64 to perform electrolytic machining. I do. Thereby, the distance S between the substrate W and the ion exchanger 84 is always equal to the thickness t of the insulating spacer 86 (t = S) without controlling the rotational speed of the motor 56 and the hollow motor 60 for rotation. , 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less, and further 1 μm or less.

  Thus, by setting the distance S between the substrate W and the ion exchanger 84 to 100 μm or less, preferably 50 μm or less, more preferably 10 μm or less, and further 1 μm or less, for example, unevenness provided on the substrate such as a semiconductor wafer. The surface of the conductive film having a surface is processed flat while eliminating the unevenness, and the electrolytic processing is performed without sliding the ion exchanger 84 and the surface of the substrate W to each other. It is possible to prevent defects on the surface and wear of the ion exchanger 84.

  In each of the above embodiments, the substrate holding portion 42 is rotated and the electrode portion 44 is scrolled at the same time, so that the substrate W, the processing electrode 62 and the feeding electrode 64 are moved relative to each other to perform processing. However, the relative motion between the substrate W and the electrode portion 44 is not limited to this, and at least one of them may rotate, eccentrically rotate, translate, reciprocate, or scroll.

  In addition, an example is shown in which the machining electrode 62 and the feeding electrode 64 are embedded in the electrode portion 44 so that the machining electrode 62 and the feeding electrode 64 do not move relative to each other. However, the machining electrode and the feeding electrode are separated from each other. It may be configured so that both move relatively. In this case, while supplying a liquid between at least one of the processing electrode and the feeding electrode and the substrate, the two are relatively moved, and the distance between the two is controlled to a predetermined value of 100 μm or less to perform electrolytic processing. Also good. In addition, an ion exchanger is attached to at least one of the processing electrode and the power supply electrode, and a liquid is supplied between the electrode to which the ion exchanger is attached and the substrate, and the two are moved relative to each other. The electrolytic processing may be performed by controlling the distance to a predetermined value of 100 μm or less.

It is a figure which shows one manufacture example of a copper wiring board in order of a process. It is a top view which shows the structure of the substrate processing apparatus provided with the electrolytic processing apparatus in embodiment of this invention. FIG. 3 is a longitudinal front view schematically showing the electrolytic processing apparatus shown in FIG. 2. It is a figure which shows the relationship between the process electrode in a process, and a to-be-processed object (board | substrate). It is a figure which shows the relationship between the residual level | step difference of the surface of an electroconductive film, and a process amount when changing the distance between a to-be-processed object (board | substrate) and an electrode (processed electrode), and performing electrolytic processing. (A) is the graph which shows the relationship between the electric current which flows when the surface of the board | substrate which formed the different material into a film is electrolytically processed, and time, (b) is the graph which respectively shows the relationship between the applied voltage and time. . It is a vertical front view which shows typically the electrolytic processing apparatus of other embodiment of this invention. It is a vertical front view which shows typically the electrolytic processing apparatus of other embodiment of this invention. It is a vertical front view which shows typically the electrolytic processing apparatus of other embodiment of this invention. It is a vertical front view which shows typically the electrolytic processing apparatus of other embodiment of this invention. It is a vertical front view which shows typically the electrolytic processing apparatus of other embodiment of this invention.

Explanation of symbols

30 load / unload unit 31a, 31b washing machine 32 reversing machine 34, 34a, 34b, 34c, 34d, 34e electrolytic processing device 36 transport robot 38 control unit 40 arm 42 substrate holding unit 44 electrode unit 44a liquid channel 44b liquid supply Hole 46 Power source 56 Rotating motor 60 Hollow motor 62 Processing electrode 64 Power supply electrode 66 Liquid supply source 68 Liquid supply pipe 70 Housing 72 Chucking plate 74 Elastic body 76 Air chamber 80 Detector 82 Liquid supply nozzle 84 Ion exchanger 86 Insulating spacer

Claims (19)

A machining electrode that is freely accessible to the workpiece;
A feeding electrode for feeding power to the workpiece;
A power source for applying a voltage between the machining electrode and the power supply electrode;
A drive unit that relatively moves the workpiece and at least one of the processing electrode or the feeding electrode;
A liquid supply section for supplying a liquid between the workpiece and at least one of the processing electrode or the feeding electrode;
A detector for detecting a distance between the workpiece and at least one of the processing electrode or the feeding electrode;
An electrolysis system comprising: a control unit that controls a distance between the workpiece and at least one of the processing electrode and the power feeding electrode to a predetermined value that is 100 μm or less and non-contact based on a signal from the detector. Processing equipment. A machining electrode that is freely accessible to the workpiece;
A feeding electrode for feeding power to the workpiece;
A power source for applying a voltage between the machining electrode and the power supply electrode;
A drive unit that relatively moves the workpiece and at least one of the processing electrode or the feeding electrode;
A liquid supply section for supplying a liquid between the workpiece and at least one of the processing electrode or the feeding electrode;
An ion exchanger disposed between the workpiece and at least one of the processing electrode or the feeding electrode;
A detector for detecting a distance between the workpiece and the ion exchanger;
An electrolytic processing apparatus comprising: a control unit configured to control a distance between the workpiece and the ion exchanger to a predetermined value that is 100 μm or less and non-contact based on a signal from the detector.   3. The electrolytic processing apparatus according to claim 1, further comprising a holding unit that floats and supports the workpiece so as to be movable toward and away from at least one of the processing electrode and the power feeding electrode.   The control unit is configured such that a pressure of a liquid supplied between the workpiece and at least one of the machining electrode or the power feeding electrode, and between the workpiece and at least one of the machining electrode or the power feeding electrode. 4. The electrolytic processing apparatus according to claim 1, wherein at least one of a relative motion speed and a voltage applied between the processing electrode and the power feeding electrode is controlled. 5. A machining electrode that is freely accessible to the workpiece;
A feeding electrode for feeding power to the workpiece;
A power source for applying a voltage between the machining electrode and the power supply electrode;
A drive unit that relatively moves the workpiece and at least one of the processing electrode or the feeding electrode;
A liquid supply section for supplying a liquid between the workpiece and at least one of the processing electrode or the feeding electrode;
An electrolytic processing apparatus comprising: an insulating spacer having a thickness of 100 μm or less disposed between the workpiece and at least one of the processing electrode or the feeding electrode. A machining electrode that is freely accessible to the workpiece;
A feeding electrode for feeding power to the workpiece;
A power source for applying a voltage between the machining electrode and the power supply electrode;
A drive unit that relatively moves the workpiece and at least one of the processing electrode or the feeding electrode;
A liquid supply section for supplying a liquid between the workpiece and at least one of the processing electrode or the feeding electrode;
An ion exchanger disposed between the workpiece and at least one of the processing electrode or the feeding electrode;
An electrolytic processing apparatus comprising an insulating spacer having a thickness of 100 μm or less disposed between the workpiece and the ion exchanger.   The electrolytic processing apparatus according to claim 5, wherein the insulating spacer is made of a porous material.   The liquid supply unit supplies liquid from at least one of a direction in which a liquid jet collides with the workpiece or a side between the workpiece and at least one of the machining electrode and the power feeding electrode. The electrolytic processing apparatus according to any one of claims 1 to 7, wherein Prepare a machining electrode that is freely accessible to the workpiece and a feed electrode that feeds the workpiece,
While maintaining the distance between the workpiece and at least one of the processing electrode or the feeding electrode at a predetermined value which is 100 μm or less and non-contact with each other, at least one of the workpiece and the processing electrode or the feeding electrode is liquid Relative movement in the presence of
An electrolytic machining method, wherein a voltage is applied between the machining electrode and the feeding electrode.   Due to the pressure of the liquid supplied between the workpiece and at least one of the machining electrode or the feeding electrode, the distance between the workpiece and at least one of the machining electrode or the feeding electrode is 100 μm or less. 10. The electrolytic processing method according to claim 9, wherein the predetermined value is non-contact.   The distance between the workpiece and at least one of the processing electrode or the feeding electrode is 100 μm or less due to the pressure of the liquid generated by the relative movement between the workpiece and at least one of the processing electrode or the feeding electrode. The electrolytic processing method according to claim 9, wherein the predetermined values are not in contact with each other. Prepare a machining electrode that is freely accessible to the workpiece and a feed electrode that feeds the workpiece,
An ion exchanger is disposed between the workpiece and at least one of the processing electrode or the feeding electrode,
While maintaining the distance between the workpiece and the ion exchanger at a predetermined value of 100 μm or less and non-contact with each other, the workpiece and at least one of the machining electrode and the feeding electrode are relatively positioned in the presence of a liquid. Exercise,
An electrolytic machining method, wherein a voltage is applied between the machining electrode and the feeding electrode.   The distance between the workpiece and the ion exchanger is maintained at a predetermined value that is not in contact with each other at a distance of 100 μm or less due to the pressure of the liquid existing between the workpiece and at least one of the machining electrode or the feeding electrode. The electrolytic processing method according to claim 12, wherein:   Due to the pressure of the liquid generated by the relative movement between the workpiece and at least one of the machining electrode or the power feeding electrode, the distance between the workpiece and the ion exchanger is 100 μm or less and is not in contact with each other. The electrolytic processing method according to claim 12, wherein the value is held at a value.   The relative motion is any one of a rotational motion, a translational motion, a linear motion, a scroll motion, a reciprocating motion, or a combination thereof, and a relative motion speed is 0.1 m / s or more. The electrolytic processing method according to any one of 11 to 14. Prepare a machining electrode that is freely accessible to the workpiece and a feed electrode that feeds the workpiece,
An insulating spacer having a thickness of 100 μm or less is disposed between the workpiece and at least one of the processing electrode or the feeding electrode,
The workpiece and at least one of the processing electrode or the feeding electrode are moved relative to each other in contact with the insulating spacer in the presence of a liquid,
An electrolytic machining method, wherein a voltage is applied between the machining electrode and the feeding electrode. Prepare a machining electrode that is freely accessible to the workpiece and a feed electrode that feeds the workpiece,
An ion exchanger is disposed between the workpiece and at least one of the processing electrode or the feeding electrode,
An insulating spacer having a thickness of 100 μm or less is disposed between the workpiece and the ion exchanger in contact with the ion exchanger,
Causing at least one of the workpiece and the processing electrode or the feeding electrode to move relative to each other while being in contact with the insulating spacer and the ion exchanger in the presence of a liquid;
An electrolytic machining method, wherein a voltage is applied between the machining electrode and the feeding electrode.   The electrolytic processing method according to claim 16, wherein the insulating spacer is made of a porous material.   The liquid is supplied from at least one of a direction in which a liquid jet collides with the workpiece or a side between the workpiece and at least one of the machining electrode or the feeding electrode. Item 19. The electrolytic processing method according to any one of Items 9 to 18.

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