JP2009295914A - Polishing pad, electrolytic compound polishing device, and electrolytic compound polishing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad with which variation of processing speed becomes smaller than permitted variation ratio if rotation speed of the polishing pad is set within a range of 25-150 rpm which is the normally used rotation speed, to provide an electrolytic compound polishing device, and to provide an electrolytic compound polishing method. <P>SOLUTION: The polishing pad 101 has a through-hole to be installed on the opposite electrode of the electrolytic compound polishing device used for electrolytic compound polishing of a metal film on the substrate surface, and is characterized in that a hole diameter D of the through-hole 101a is within a range of 0.1-5 mm, a thickness h is within a range of 0.5-5 mm, and square of the hole diameter/thickness (D<SP>2</SP>/h) is within a range of 0.002-50 mm. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing pad to be used for electrolytic composite polishing, an electrolytic composite polishing apparatus, and an electrolytic composite polishing method, and more particularly, an electroconductive material (metal film) formed on a substrate surface such as a semiconductor wafer with an electrochemical action and mechanical properties. The present invention relates to a polishing pad suitable for electrolytic composite polishing in which actions are combined, and to an electrolytic composite polishing apparatus and an electrolytic composite polishing method.

  As a wiring formation process of a semiconductor device, there is a so-called damascene process in which a wiring metal is embedded in a wiring recess such as a trench or a via hole provided in an insulating film, instead of patterning a metal film as a wiring material. It is being used.

  This damascene process will be described with reference to FIG. 47. As shown in FIG. 47A, a wiring recess (hereinafter referred to as “recessed wiring”) is formed in an insulating film (interlayer insulating film) 62 made of a so-called Low-k material on the substrate W. 63), and then a barrier metal film (hereinafter referred to as "barrier film") 64 made of titanium nitride or the like is formed on the entire surface of the interlayer insulating film 62 including the recess 63. A metal conductive film (hereinafter referred to as “conductive film”) 66 made of copper, tungsten, or the like is formed, and a metal conductive material is embedded in the recess 63. Thereafter, the excess conductive film 66 and barrier film 64 formed outside the concave portion 63 are removed, thereby flattening the irregularities on the substrate W as shown in FIG. Then, a wiring made of the conductive film 66 is formed.

  Here, the removal of the excess metal film (the conductive film 66 and the barrier film 64) is generally performed by a planarization method such as chemical mechanical polishing (CMP), electrolytic polishing, and electrolytic composite polishing.

  Among them, in the electrolytic composite polishing, as shown in FIG. 47B, an electrolytic solution 50 is supplied between the conductive film 66 on the surface of the substrate W and a counter electrode (not shown), and the conductive film 66 and the counter electrode The surface of the conductive film 66 is polished by relatively moving the substrate W and the polishing pad 101 while applying a voltage between them while pressing the surface of the substrate W against the polishing pad 101. In some cases, the term “electrolytic polishing” is used as a derivative technique of “electrolytic polishing” in the term “electrolytic polishing”. However, in this specification, the term “electrolytic polishing” is used in a unified manner. .

  In this electrolytic composite polishing, by applying a voltage between the conductive film 66 and the counter electrode, the conductive film 66 is dissolved electrochemically and the electrolytic polishing proceeds. On the other hand, when there is a protective film forming component in the electrolytic solution 50, the protective film 70 made of a metal complex is formed on the surface of the conductive film 66, so that polishing is suppressed. As shown in FIG. 47A, assuming that a concave portion 67 is formed on the surface of the conductive film 66 following the concave portion 63 formed on the surface of the interlayer insulating film 62, FIG. 2, the protective film formed on the upper stage H (outside the recess 67) H of the conductive film 66 is removed by contact with the polishing pad 101, and the conductive film 66 in the part is dissolved in the electrolytic solution 50. . On the other hand, the conductive film 66 in the lower step portion (inside the recess 67) L is shielded by the protective film 70 and is not dissolved in the electrolytic solution 50, or even if dissolved, it is dissolved as compared with the upper step portion H of the conductive film 66. The amount is small. By repeating such steps, the surface of the conductive film 66 is planarized.

  Here, the polishing pad 101 is provided with a through hole so that charge carriers such as ions can move between the conductive film 66 and the counter electrode. The electrolytic solution 50 exists in the through hole, and the charge carrier moves through the electrolytic solution 50. Patent Documents 1 and 2 disclose the diameter of the through hole of the polishing pad in the electrolytic composite polishing and the ratio (opening ratio) of the opening area of the through hole in the region in contact with the conductive film 66 of the polishing pad. . That is, the hole diameter of the through hole (perforated in Patent Documents 1 and 2) of a polishing pad equivalent (a polished article or a polishing article in Patent Documents 1 and 2) corresponding to the polishing pad includes about 0.5 mm to about 10 mm. Further, it is disclosed that the aperture ratio (perforation density in Patent Documents 1 and 2) is about 20% to about 80%, and about 50% is good. Moreover, it is described in patent documents 1 and 2 that the thickness of the polishing pad equivalent may be about 0.1 mm to about 5 mm. Note that the polishing pad equivalent (polishing product or polishing article) in Patent Documents 1 and 2 is considered to be a composite part having a conductive polishing portion and a subpad portion, and the above thickness is shown as the total thickness of these components. It is a thing.

Further, for the relative movement between the substrate W and the polishing pad 101, there may be employed a method in which the substrate W and the polishing pad 101 each rotate about different rotation axes. Regarding this rotational motion, Patent Documents 1 and 2 describe that the rotational speed of the polishing pad (the platen speed in Patent Documents 1 and 2) is about 5 rpm or more (for example, between about 10 rpm and about 50 rpm), and about 150 rpm or more ( For example, between about 150 rpm and about 750 rpm).
JP 2004-134732 A JP-A-2005-005661

  By the way, when electrolytic composite polishing is performed while rotating a polishing pad having a through-hole around the rotation axis, if the polishing pad rotates at a higher speed, the amount of decrease in the conductive film thickness per unit time (processing speed) is reduced. May be smaller. If the change in the processing speed is small when the rotation speed of the polishing pad is changed, there is no problem, but if the change in the processing speed is large, the operating condition range (process window) is narrowed. However, in the inventions described in Patent Documents 1 and 2 described above, the range of the hole diameter, the range of thickness, and the range of the rotation speed of the polishing pad are not referred to the relationship between the rotation speed of the polishing pad and the processing speed. It has been decided. Also, in the electrolytic composite polishing process, the range of the rotational speed of the polishing pad is different from the rotational speed used in the conventional CMP apparatus. Therefore, when the existing CMP apparatus is modified to an electrolytic composite polishing apparatus, the polishing pad drive system Changes may be required.

  The present invention has been made in view of the above circumstances, and in consideration of the relationship between the rotational speed of the polishing pad at the time of electrolytic composite polishing and the processing speed, a suitable shape used for an electrolytic composite polishing apparatus, An object of the present invention is to provide a polished polishing pad. In addition, even when the polishing pad is set to rotate within the range of 25 rpm to 150 rpm, which is a rotation speed normally used in conventional CMP, at the time of electrolytic composite polishing, the change rate of the processing speed is allowed to change. An object of the present invention is to provide a polishing pad, an electrolytic composite polishing apparatus, and an electrolytic composite polishing method that are configured to be smaller.

  As a result of diligent research to achieve the above-mentioned object, the inventors have filled the through-hole with a phenomenon that the processing speed of the conductive film decreases as the rotational speed of the polishing pad increases as described below. It was found to correlate with the filling rate of the electrolyte.

  In the present invention, even when the polishing pad has a through hole that communicates both surfaces thereof (that is, the surface in contact with the substrate and the opposite surface), when performing the electrolytic composite polishing, the polishing pad is supported, for example, In the aspect mounted on the member, a technique is disclosed in which one of the through holes is closed by the support member or the like, and substantially only one of the openings functions as a closed hole. .

  The polishing pad of the present invention is a polishing pad having a through-hole installed on a counter electrode of an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface, and the through-hole has a hole diameter of 0. 0. It is characterized by being in a range of 1 mm to 5 mm, a thickness of 0.5 mm to 5 mm, and a square of the hole diameter / thickness of 0.002 mm to 50 mm.

  If comprised in this way, the shape of a polishing pad is prescribed | regulated, after evaluating the relationship between the rotational speed of a polishing pad and the polishing process speed at the time of carrying out electrolytic composite polishing of a board | substrate, Therefore, an electrolytic composite polishing process is suitable Can be performed under various conditions.

One preferable aspect of the present invention is characterized in that the polishing pad has a multilayer structure.
With this configuration, for example, the lower layer (that is, the layer on the counter electrode side) is formed of a relatively soft material, and the upper layer (that is, the layer on the substrate side) is formed of a hard material. Therefore, electrolytic composite polishing can be performed more suitably.

In a preferred aspect of the present invention, the polishing pad further includes a base layer having a through hole on the surface on the counter electrode side, and at least a part of the through hole of the base layer is in contact with the metal film of the polishing pad. It is characterized by communicating with the surface.
Thus, if a polishing pad is further provided with a base layer, the hole diameter of the through hole in the base layer is not restricted to the range of 0.1 mm to 5 mm, and the shape of the through hole is limited to a circle. Therefore, for example, a sheet having a mesh structure may be used as the base layer, and the degree of freedom in selecting a polishing pad material can be increased.

In a preferred aspect of the present invention, the layer in contact with the metal film on the surface of the substrate of the polishing pad has conductivity.
According to this structure, for example, if the lower layer (base layer) of the polishing pad is formed of an insulating material, voltage application from the power source to the metal film on the substrate surface is performed via the conductive layer. Can be done. That is, since power can be supplied from the outermost surface layer of the polishing pad to almost the entire surface of the metal film, the contact effect can be reduced and the uniformity of the processing speed in the substrate can be improved.

Another polishing pad of the present invention is a polishing pad having a through hole installed on a counter electrode of an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface, and the through hole has a hole diameter. It is characterized by being in a range of 0.1 mm to 5 mm and a thickness of 0.1 mm to 0.5 mm.
If comprised in this way, the shape of a polishing pad is prescribed | regulated, after evaluating the relationship between the rotational speed of a polishing pad at the time of electrolytic composite polishing of a board | substrate, and a processing speed, Therefore, electrolytic composite polishing processing is suitable. Can be done under conditions.

One preferable aspect of the present invention is characterized in that the opening ratio of the through holes of the polishing pad is in the range of 20% to 70%.
With this configuration, it is possible to provide a polishing pad capable of processing with good step resolution while maintaining a suitable processing speed.

  The polishing article of the present invention is a polishing article placed on a counter electrode of an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface, and polishing any of the above polishing pads A pad and a conductive closing member provided on the surface of the polishing pad on the counter electrode side are provided.

  If comprised in this way, since either of the above-mentioned polishing pads and the above-mentioned closure member can be mutually fixed with an adhesive etc., for example, it has the feature of the above-mentioned polishing pad, and the through-hole of the polishing pad is reliably closed It can be set as this aspect. Here, since the closing member has conductivity, the electrolytic composite polishing process can be suitably executed.

  The electrolytic composite polishing apparatus of the present invention is an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface, and is provided with a counter electrode and the metal on the counter electrode and the substrate surface installed on the counter electrode. A polishing pad having a through hole communicating with the membrane, the hole diameter of the through hole being 0.1 mm to 5 mm, the depth of the through hole being 0.5 mm to 5 mm, and the square of the hole diameter / depth Is in the range of 0.002 mm to 50 mm.

  If comprised in this way, since the polishing pad in which the relationship between the rotation speed of the polishing pad and the polishing processing speed at the time of polishing the substrate was evaluated can be used, it is possible to perform electrolytic composite polishing processing under suitable conditions. A composite polishing apparatus can be provided.

One preferable aspect of the present invention is characterized in that the polishing pad has a multilayer structure.
If comprised in this way, the polishing pad which formed the lower layer (namely, the layer by the side of a counter electrode) of this polishing pad with a comparatively soft material and the upper layer (namely, the layer by the side of a board | substrate) can be used, for example. Thus, it is possible to provide an electrolytic composite polishing apparatus capable of uniforming the processing speed of the entire substrate and eliminating local steps.

In a preferred aspect of the present invention, the polishing pad further includes a base layer having a through hole on the surface on the counter electrode side, and at least a part of the through hole of the base layer is on the surface in contact with the metal film of the polishing pad. It is made to communicate.
If constituted in this way, for example, since the hole diameter of the base layer of the polishing pad is not restricted to the range of 0.1 mm to 5 mm, the degree of freedom in selecting the polishing pad material is increased. Since it can increase, the electrolytic composite grinding | polishing apparatus more suitable for the said electropolishing can be provided.

One preferred embodiment of the present invention is characterized in that the layer in contact with the metal film on the substrate surface of the polishing pad has conductivity.
With this configuration, for example, voltage can be applied from the power source to the metal film on the surface of the substrate via the conductive layer, so that favorable processing while maintaining uniformity of processing speed within the substrate is possible. Can be provided.

  Another electrolytic composite polishing apparatus of the present invention is an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface, the counter electrode and the counter electrode installed on the counter electrode and the substrate surface. A polishing pad having a through hole communicating with the metal film, wherein the through hole has a diameter of 0.1 mm to 5 mm and a depth of the through hole of 0.1 mm to 0.5 mm. It is characterized by that.

  If comprised in this way, since the polishing pad in which the relationship between the rotation speed of the polishing pad and the polishing processing speed at the time of polishing the substrate was evaluated can be used, it is possible to perform electrolytic composite polishing processing under suitable conditions. A composite polishing apparatus can be provided.

One preferable aspect of the present invention is characterized in that an opening ratio of the through hole of the polishing pad is in a range of 20% to 70%.
If comprised in this way, the electrolytic compound grinding | polishing apparatus which can process with sufficient level | step difference elimination property, for example can be provided, maintaining a suitable processing speed.

Still another electrolytic composite polishing apparatus of the present invention is an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface, wherein a counter electrode and a blocking member on the counter electrode are in contact with the counter electrode. The polishing article is a polishing article including any of the polishing pads disclosed above and the conductive closing member.
If comprised in this way, since the opening part by the side of the counter electrode of the through-hole of a polishing pad is reliably obstruct | occluded by the said obstruction | occlusion member, the electrolytic complex polishing apparatus which can perform suitable grinding | polishing can be provided.

In the electrolytic composite polishing method of the present invention, an electrolytic solution is present between the metal film on the substrate surface and the counter electrode, and a voltage is applied between the metal film and the counter electrode while the substrate surface is placed on the counter electrode. In the electrolytic composite polishing method of polishing the surface of the metal film by moving the substrate and the polishing pad relative to each other while pressing against the installed polishing pad, the counter electrode and the metal film on the substrate surface are used as the polishing pad. A polishing pad having a through hole with a hole diameter in a range of 0.1 mm to 5 mm, a rotation speed of the polishing pad in a range of 40 rpm to 150 rpm, and a square of the hole diameter of the through hole × depth of square / the through hole of the angular velocity of the rotational movement, characterized in that rotating the polishing pad to be in the range of ^{0.01mm / s 2 ~10,000mm / s 2} .

  According to the above method, since the polishing pad in which the relationship between the rotation speed of the polishing pad and the polishing processing speed when polishing the substrate is used is used, the electrolytic composite capable of performing the electrolytic composite polishing process under suitable conditions. A polishing method can be provided.

In a preferred aspect of the present invention, the relationship between the rotational speed v _p (rpm) of the polishing pad and the opening ratio γ (%) of the through hole of the polishing pad is v _p ≧ 17 × exp (0.03 × γ). It is characterized by being.
As a result, a polishing pad having an appropriate aperture ratio corresponding to the range of change in the rotation speed of the polishing pad during the electrolytic composite polishing process can be used, so that a suitable electrolytic composite polishing process can be performed. Also, an operation such as using a different polishing pad is possible depending on the operating conditions of the electrolytic composite polishing process.

In another electrolytic composite polishing method of the present invention, an electrolytic solution is present between a metal film on a substrate surface and a counter electrode, and a voltage is applied between the metal film and the counter electrode while the substrate surface is placed on the counter electrode. In the electrolytic composite polishing method for polishing the surface of the metal film by relatively moving the substrate and the polishing article while pressing against a polishing article placed on the polishing article, a polishing pad having a through-hole as the polishing article and the polishing pad A polishing article comprising a conductive blocking member provided on the surface of the polishing pad facing the counter electrode is used, the polishing article has a rotational speed in the range of 40 rpm to 150 rpm, and the polishing pad penetrates. that square / depth of the through hole of the angular velocity squared × the rotational motion of the pores of the rotating the abrasive article to be in the range of 0.01mm ^{/ s 2} ~10,000mm ^/ s 2 Features .

  According to the above method, since the polishing article is used, the polishing article having the polishing pad evaluated for the relationship between the rotation speed of the polishing pad and the polishing processing speed when polishing the substrate is used. An electrolytic composite polishing method capable of performing processing under suitable conditions can be provided.

  According to the present invention, it has been clarified that the processing speed of the conductive film is strongly related to the filling rate of the electrolytic solution in the through hole of the polishing pad, and the processing speed due to the change in the rotation speed of the polishing pad is reduced. A polishing pad whose rate of change is kept small enough to withstand practical use, and the diameter and depth of the through hole (the depth is the thickness of the polishing pad if the surface on which the polishing pad of the support member is placed is flat) Can be provided by selecting Further, if the rotational speed of the polishing pad is set within a range normally used in a CMP apparatus, for example, a polishing pad, an electrolytic composite polishing apparatus, and an electrolytic composite polishing method in which a change in processing speed is smaller than an allowable change rate. Can be provided.

Next, embodiments of the present invention will be described with reference to the drawings.
First, the fact that the phenomenon that the processing speed of the conductive film decreases as the rotation speed of the polishing pad increases, which the inventors have clarified, correlates with the filling rate of the electrolytic solution filled in the through holes will be described below. To do.

  FIGS. 1 to 5 show the electrolytic polishing of copper as a conductive film, in which the rotational speed of the polishing pad is 30 rpm to 105 rpm, the electrolyte supply amount is 100 mL / min to 2,000 mL / min, and the hole diameter ( Hereinafter, the diameter of the hole is also 2 mm to 20 mm, the pressure for pressing the substrate against the polishing pad is 0.2 psi (about 1.4 kPa) to 1 psi (about 6.9 kPa), and the opening ratio of the through hole is 15% to 45%. The measurement results of filling rate (experimental value) and processing speed when changed in the range of% are shown.

  The experimental value of the filling rate was calculated by collecting the electrolyte remaining in the through-hole immediately after the polishing pad stopped rotating and dividing the volume calculated from the weight of the collected electrolyte by the volume of the through-hole. did. The electrolytic solution was recovered from the through hole where the vicinity of the center of the substrate passes. Moreover, the experimental value of the processing speed was calculated by dividing the copper film thickness before and after electrolytic composite polishing converted from the sheet resistance measured by the direct current four-probe method by the processing time.

  FIG. 1 shows the relationship between the filling rate and the processing speed when the rotational speed of the polishing pad is 30 rpm to 105 rpm. As can be seen from FIG. 1, the filling rate decreases as the rotational speed of the polishing pad increases, and the processing speed also decreases. FIG. 2 shows the relationship between the filling rate and the processing speed when the electrolytic solution supply rate is 100 mL / min to 2,000 mL / min. From FIG. 2, it can be seen that as the electrolyte supply amount increases, the filling rate increases and the processing speed also increases.

  FIG. 3 shows the relationship between the filling rate and the processing speed when the hole diameter (diameter) of the through hole is 2 mm to 20 mm. From FIG. 3, it can be seen that as the hole diameter (diameter) of the through-hole increases, the filling rate decreases, and the processing speed also decreases. FIG. 4 shows the relationship between the filling rate and the processing speed when the pressure for pressing the substrate against the polishing pad is 0.2 psi (about 1.4 kPa) to 1 psi (about 6.9 kPa). From FIG. 4, it can be seen that even if the pressure for pressing the substrate against the polishing pad is changed within this range, the filling rate hardly changes, and similarly the processing speed hardly changes.

  On the other hand, FIG. 5 shows the filling rate and processing speed when the opening ratio of the through holes (the ratio of the opening area of the through holes in the surface region in contact with the conductive film of the polishing pad) is 15% to 45%. Show the relationship. FIG. 5 shows that as the opening ratio of the through-hole increases, the filling rate decreases slightly, but the processing speed increases slightly. This tendency is different from other parameters. Here, from the result of changing the polishing pad rotation speed, the electrolyte supply amount, the through hole diameter and the pressing pressure shown in FIGS. 1 to 4 above, it is considered that the processing speed is affected by the filling rate, According to FIG. 5, it can be considered from the results regarding the aperture ratio that the processing speed is more greatly affected by the protective film than the influence of the filling rate. Therefore, the opening ratio of the through hole is excluded from the correlation between the filling rate and the processing speed.

  FIG. 6 shows that the aperture ratio of the through hole is fixed to about 30%, the rotation speed of the polishing pad is 30 rpm to 105 rpm, the electrolyte supply amount is 100 mL / min to 2,000 mL / min, and the hole diameter of the through hole is 2 mm to 20 mm. , Shows the experimental results when the pressure for pressing the substrate against the polishing pad is changed in the range of 0.2 psi (about 1.4 kPa) to 1 psi (about 6.9 kPa), and the processing speed depends on the filling rate It is the result of examining sex. In FIG. 6, the diamond mark is a result when there is a shallow lattice-like groove that does not penetrate to the counter electrode on the surface of the polishing pad that is in contact with the substrate W, and the square mark is a result when there is no groove. From FIG. 6, it can be seen that there is a strong correlation between the filling rate and the processing speed, and that it is hardly influenced by the presence or absence of shallow grooves.

  Therefore, if the filling rate can be determined from the process conditions such as the polishing pad rotation speed, the amount of electrolyte supplied, and the hole diameter of the through hole, the rough processing speed can be predicted, and further, the processing can be performed even if the polishing pad rotation speed is changed. It is thought that the condition that the change in speed is small can be found. Therefore, an attempt was made to estimate the filling rate by a simple calculation. Below, the calculation method of a filling rate is demonstrated.

  FIG. 7 is a schematic view of a main part of the electrolytic composite polishing apparatus. As shown in FIG. 7, a support member 254 made of a conductive material is fixed on a polishing table 100 having a rotating shaft. The polishing pad 101 is attached to the upper surface of the support member 254, and the upper surface of the polishing pad 101 is a polishing surface. The polishing table 100 is connected to a rotation mechanism (not shown) such as a motor, so that the polishing table 100 can rotate integrally with the support member 254 and the polishing pad 101.

  The conductive film on the surface of the substrate W is connected to the anode of the power source 252. The support member 254 is connected to the cathode of the power source 252 and functions as a counter electrode of the substrate W. The support member 254 as the cathode and the conductive film on the substrate W as the anode are electrically connected through the electrolytic solution 50 filled in the through hole 101 a of the polishing pad 101. As a result, the conductive film is dissolved electrochemically and the electrolytic polishing proceeds.

FIGS. 8A to 8C show the electrolytic solution supply region B _I , the electrolytic solution supply region B _II when the polishing pad 101 shown in FIG. 7 rotates in the direction of the arrow B shown in FIG. it is a schematic diagram showing the filling degree of the electrolytic solution 50 in the through hole 101a in the polishing region B _III. 8A to 8C, in any region B _{I to} B _III , the center of rotation of the polishing pad 101 is on the right side of the figure, and the centrifugal force due to the rotation of the polishing pad 101 is in the left direction of the figure. is working.

In the region _BI , as shown in FIG. 8A, the liquid surface of the electrolytic solution 50a in the through hole 101a is inclined by the centrifugal force, and the electrolytic solution 50a flows out of the through hole 101a. On the other hand, there is also an inflow of the electrolyte that has been discharged from the through hole on the rotation center side. In region B _II, as shown in FIG. 8 (b), the electrolyte solution 50a which is filled in the through hole 101a in the region _{B I,} the electrolyte 50b is added supplied from the electrolytic solution supply nozzle 102. In the region _BIII , as shown in FIG. 8C, the opening of the through hole 101a is closed by the substrate W, and the electrolytic solution 50c is confined in the through hole 101a. At that time, a space 101b is generated in the through hole.

Here, the electrolyte solution filling ratio of the through-hole 101a in the region B _III, the volume of the volume / through-hole 101a of the electrolyte solution 50c, when defined as the volume of the electrolyte 50a in the through hole 101a in the region _{B I} from the volume of the electrolyte 50b is supplied in the region B _II, electrolyte filling ratio of the through hole 101 in the region B _III can typically be defined as the following equation 1.

Filling ratio = volume of electrolytic solution 50c / volume of through hole 101a
≒ volume (area _{B I} in a volume of the through-hole of the electrolyte solution 50a in the 101a volume + region B _II with the through hole 101a electrolyte is fed into 50b) ÷ through hole 101a (Equation 1)

  As is clear from the definition of the filling rate, the through hole 101a of the polishing pad 101 in the present invention refers to both surfaces of the polishing pad 101 (that is, the surface in contact with the support member 254 and the like) in the polishing pad 101 alone. Even if it penetrates so as to communicate with the substrate (the surface in contact with the substrate W), it means a through hole that is placed on the support member 254 and forms a closed hole together with the support member 254, for example. Further, the polishing pad is provided with a conductive blocking member, and the blocking pad (that is, the surface that opens to only the surface that contacts the substrate W without communicating both surfaces of the polishing pad 101 as described above, and the surface that contacts the support member 254) Even if a closed hole is formed by the closing member, the effect of the closing hole in the electrolytic polishing step is equivalent to that of the through-hole 101a. Therefore, a polishing pad having such a closing hole is used. Is also included in the present invention.

  The method for deriving the filling rate by simple calculation will be described below. In the present specification, the filling rate derived here is referred to as a “virtual filling rate”.

In the volume of the electrolyte 50a in the through hole 101a is the region B _I, electrolyte flowing out of the sum of the volume of the electrolyte which flows the volume of the electrolyte solution when the liquid surface in the centrifugal force is inclined relative to the horizontal plane This can be approximated by the following equation 2.

The volume of the volume ≒ through hole 101a of the electrolytic solution 50a in the through hole 101a in the region B _I - the volume of the space portion 101c when the liquid surface by the coefficient C × centrifugal force is inclined relative to the horizontal plane (Equation 2)

  Here, the volume of the space portion 101c when the surface of the electrolytic solution is inclined with respect to the horizontal plane by centrifugal force is the polishing pad 101 in a state where the electrolytic solution 50 is filled in the through-hole 101a and the electrolytic solution 50 is not supplied. 9, the volume of the space portion 101c remaining in the through-hole 101a finally (in a steady state) as shown in FIG.

The volume of the space portion 101c when tilted by the centrifugal force can be obtained from the tilt of the liquid surface due to the balance between the centrifugal force and gravity. The angular velocity due to the rotation of the polishing pad 101 is ω, and the through hole 101a from the center of rotation of the polishing pad. When the distance to the center is R ₀ , the hole diameter (diameter) of the through hole 101a is D, the depth of the through hole 101a is h, and the gravitational acceleration is g, for example, in the range of R ₀ × ω ² / g ≦ h / D Can be approximated by Equation 3 below.

Here, V _h is the volume (πD ² h / 4) of the through hole 101a.
The volume of the electrolyte 50b is supplied into the through hole 101a in the region B _II can be approximated by the following equation 4.

Where Q is the electrolyte supply flow rate, L _II is the length in the circumferential direction of the polishing pad in region B _II , R _C is the distance from the center of rotation of the polishing pad to the center of rotation of the substrate, and D _W is the diameter of the substrate W is there.
From the above formulas 1 to 4, the virtual filling rate in the range of R ₀ × ω ² / g ≦ h / D is expressed by the following formula 5.

ここで、上記φは式７で表される。

Here, as a result of intensive studies, it has been conceived that a good correlation with the experimental results can be obtained by setting the coefficient C of Equation 2 to a dimensionless number proportional to the hole diameter D of the through hole. When the calculation result of the virtual filling rate exceeds 1, the virtual filling rate is 1. Further, the volume of the space portion 101c when tilted by the centrifugal force in the range of R ₀ × ω ² / g> h / D can also be obtained by simple numerical integration as shown in the following equation 6. A virtual filling rate can be calculated.

Here, φ is expressed by Equation 7.

  FIG. 10 shows that in the electrolytic electrolytic polishing of copper, the opening ratio of the through hole is fixed to about 30%, the rotation speed of the polishing pad is 30 rpm to 105 rpm, the electrolytic solution supply amount is 100 mL / min to 2,000 mL / min, and the penetration Measurement results of the filling rate when the hole diameter is 2 mm to 20 mm and the pressure for pressing the substrate against the polishing pad is changed in the range of 0.2 psi (about 1.4 kPa) to 1 psi (about 6.9 kPa) (FIG. 10). 11 is a diagram showing the relationship between “filling rate (experimental value)” and virtual filling rate (shown as “virtual filling rate (calculated value)” in FIG. 10). FIG. 10 shows that there is a good correlation between the measurement result of the filling rate and the virtual filling rate.

  FIG. 11 is a diagram showing the relationship between the virtual filling rate and the processing speed measurement result. From FIG. 11, it can be seen that there is a good correlation between the virtual filling rate and the machining speed (actually measured value). That is, when the actual machining is performed under the machining condition when the value of the virtual filling rate calculated based on Equation 5 is large, a large machining speed can be obtained, and the machining condition when the value of the virtual filling rate is small. When actual machining is performed, the machining speed can be reduced. 10 and 11, the rhombus marks are the results when there are shallow lattice-like grooves that do not penetrate to the counter electrode on the surface of the polishing pad in contact with the substrate W, and the square marks are the results when there are no grooves. is there.

  Hereinafter, the results of investigation centered on the range of 25 rpm to 150 rpm, which is the rotational speed of a polishing pad normally used in conventional CMP, will be described using the above-described virtual filling rate.

  12 (a) and 13 (a) show the copper processing speed measured by changing the rotation speed of the polishing pad and the diameter of the through hole in the electrolytic composite polishing of copper as the conductive film formed on the substrate surface. It is a result. FIG. 12A shows the case where the electrolytic solution supply amount is 100 mL / min, and FIG. 13A shows the case where the electrolytic solution supply amount is 2,000 mL / min. From FIG. 12A and FIG. 13A, it can be seen that as the rotational speed of the polishing pad increases, the processing speed decreases, and the decrease rate increases as the hole diameter of the through hole increases. As shown in FIG. 12 (a), when the electrolyte supply rate is 100 mL / min, when the rotation speed of the polishing pad is changed from 25 rpm to 105 rpm, the decrease in the processing speed is about 20% when the hole diameter is 5 mm. However, when the hole diameter is 20 mm, the processing speed is reduced by nearly 80%.

  FIG. 12B and FIG. 13B show the results of calculating the virtual filling rate of the electrolytic solution by Equation 5 while changing the rotation speed of the polishing pad and the diameter of the through hole. FIG. 12B shows the case where the electrolyte supply amount is 100 mL / min, and FIG. 13B shows the case where the electrolyte supply amount is 2,000 mL / min. From the comparison between the calculation result of the virtual filling rate and the measurement result of the processing speed, that is, the comparison between FIG. 12B and FIG. 13B and FIG. 12A and FIG. And it turns out that the tendency of the calculation result of virtual filling rate shown in FIG.13 (b) is in good agreement with the measurement result of processing speed.

  In other words, when 25 rpm on the low rotation speed side is used as a reference, the ratio at which the machining speed decreases in the actual measurement value toward 105 rpm on the high rotation speed side, and the ratio at which the virtual filling rate decreases in the calculated value are almost equal. It can be seen as equivalent. For example, in the case of a hole diameter of 5 mm, according to FIG. 12 (a), the processing speeds are about 920 nm / min and 750 nm / min at the rotational speeds of the polishing pad of 25 rpm and 105 rpm, respectively. 750 / 920≈0.82, i.e. about 18% lower. According to FIG. 12 (b), the virtual filling rate is similarly reduced from about 0.98 to about 0.66, and during this time, 0.66 / 0.98≈0.67, that is, about 33%. ing.

  On the other hand, regarding FIG. 13 showing the case where the amount of electrolyte supply is relatively large, as in FIG. 12, when the diameter of the through hole is 5 mm, according to FIG. 13A, the rotational speed of the polishing pad is 25 rpm. And 105 rpm, the processing speeds are about 1070 nm / min and 840 nm / min, respectively, and 840 / 1070≈0.79, that is, about 21% lower. According to FIG. 13 (b), the virtual filling rate is also reduced from about 1.00 to about 0.73, and during this time, 0.73 / 1.00 = 0.73, that is, 27% lower. Yes.

  In FIG. 12 and FIG. 13, the electrolyte supply amount is different as a condition. However, based on the average value of these two cases, the measured value of the processing speed at the rotational speed of 105 rpm is based on the rotational speed of 25 rpm. The calculated value of the virtual filling rate decreases by approximately 30%. Thus, the decrease in the virtual filling rate is about 1.5 times the decrease in the processing speed. Therefore, although there is a difference in the value of the rate of decrease, it can be said that the correlation between the two is strong.

  If the rotational speed of the polishing pad is changed, the allowable change in the processing speed is, for example, about 25%, preferably about 15%, on the low rotational speed side. The virtual filling rate of the electrolyte satisfying this condition is 37.5% and 22.5%, respectively, which are 1.5 times of 25% and 15% based on the above correspondence with the measurement result of the processing speed. Since it can be considered that it is 40% and 20%, it can be estimated that the virtual filling rate on the high rotational speed side is about 0.6 or more, preferably about 0.8 or more. Therefore, it is only necessary to calculate the virtual filling rate of the electrolytic solution under various conditions, and search for a condition where the virtual filling rate on the high rotational speed side is about 0.6 or more, or about 0.8 or more.

  Furthermore, from the relationship between the measurement result of the filling rate shown in FIG. 6 and the processing speed, the filling rate is higher when the filling rate is about 0.4 or more than when the filling rate is less than about 0.4. The change in the machining speed with respect to the change in is small. Therefore, if electrolytic composite machining is performed under conditions such that the filling rate (experimental value) is about 0.4 or more, it can be said that the change in the machining speed can be reduced even if the polishing pad rotation speed is changed. Here, the virtual filling rate at which the filling rate (experimental value) is about 0.4 or more is about 0.8 or more with reference to FIG. 10 described above.

  The results of searching for conditions under which the change in the processing speed is small even when the rotation speed of the polishing pad is changed from the calculation result of the virtual filling rate of the electrolytic solution are shown below.

FIG. 14 shows electrolyte flow rate Q = 100 mL / min, through hole depth h = 2.6 mm, distance R ₀ = 150 mm from the center of rotation of the polishing pad to the center of the through hole, and the center of rotation of the substrate from the center of rotation of the polishing pad. This is a result of calculating the relationship between the polishing pad rotation speed and the virtual filling rate when the distance R _C = 150 mm and the substrate diameter D _W = 100 mm, while changing the hole diameter of the through hole. When the polishing pad rotational speed is 150 rpm, the virtual filling rate is about 0.6 or more when the diameter of the through hole is about 5 mm or less. Further, when the polishing pad rotation speed is 150 rpm, the virtual filling rate is about 0.8 or more when the diameter of the through hole is about 3 mm or less.

FIG. 15 shows an electrolyte flow rate Q = 900 mL / min, a through hole depth h = 2.6 mm, a distance R ₀ = 240 mm from the center of rotation of the polishing pad to the center of the through hole, and a center of rotation of the substrate from the center of rotation of the polishing pad. This is a result of calculating the relationship between the polishing pad rotation speed and the virtual filling rate when the distance R _C = 240 mm and the substrate diameter D _W = 300 mm, while changing the hole diameter of the through hole. FIG. 16 shows the electrolyte flow rate Q = 2,000 mL / min, the through hole depth h = 2.6 mm, the distance R ₀ = 315 mm from the center of rotation of the polishing pad to the center of the through hole, and the center of rotation of the polishing pad. This is a result of calculating the relationship between the polishing pad rotation speed and the virtual filling rate when the distance R _C = 315 mm to the rotation center of the substrate and the substrate diameter D _W = 450 mm and changing the hole diameter of the through hole.

  15 and FIG. 16, as in the case shown in FIG. 14, the virtual filling rate becomes about 0.6 or more at the polishing pad rotation speed of 150 rpm because the hole diameter of the through hole is about 5 mm or less. It is. Further, when the polishing pad rotation speed is 150 rpm, the virtual filling rate becomes about 0.8 or more when the diameter of the through hole is about 3 mm or less.

  From the above, the hole diameter of the through hole is preferably 5 mm or less, and more preferably 3 mm or less. Here, when the hole diameter is too small, not only does the electrolyte hardly enter the through hole and the filling rate becomes small, but there is also a problem that it takes a lot of cost and time to process a large number of through holes. Therefore, the hole diameter of the through hole is preferably 0.1 mm or more, more preferably 0.3 mm or more.

  Therefore, in a polishing pad having a through hole used for electrolytic composite polishing of a metal film on the substrate surface, the diameter (diameter) of the through hole is preferably in the range of 0.1 mm to 5 mm. More preferably, it is 3 mm to 3 mm.

  Further, in an electrolytic composite polishing apparatus having a counter electrode and a polishing pad placed on the surface of the counter electrode, which is used for electrolytic composite polishing of a metal film on the substrate surface, It is preferable to use a polishing pad having a through-hole communicating with an electrode in the polishing pad and having a through-hole diameter (diameter) of 0.1 mm to 5 mm.

FIG. 17 shows the electrolyte flow rate Q = 100 mL / min, polishing pad rotation speed = 75 rpm, distance R ₀ = 150 mm from the rotation center of the polishing pad to the center of the through hole, and distance from the rotation center of the polishing pad to the rotation center of the substrate. It is the result of having calculated the relationship between the polishing pad thickness and the virtual filling rate when R _C = 150 mm and the substrate diameter D _W = 100 mm, changing the hole diameter of the through hole. From FIG. 17, the virtual filling rate is about 0.6 or more when the diameter of the through hole is about 5 mm or less. The virtual filling rate is about 0.8 or more when the diameter of the through hole is about 3 mm or less.

  Here, as shown in FIG. 18A, it is assumed that the surface of the support member 254 serving as the cathode is flat, and the thickness of the polishing pad 101 is equal to the depth h of the through hole 101a having the hole diameter D. ing. That is, as shown in FIGS. 18A to 18D, the depth h of the through hole 101a varies depending on the structure of the cathode, and therefore does not necessarily match the thickness of the polishing pad. In FIG. 18A, the surface of the support member 254 serving as the cathode is flat, and the thickness of the polishing pad 101 is equal to the depth h of the through hole 101a. In FIG. 18B, the portion of the support member 254 serving as the cathode that forms the through-hole 101a together with the polishing pad 101 protrudes, and the thickness of the polishing pad 101 is larger than the depth h of the through-hole 101a.

  In FIG. 18C, the cathode 254a is installed in the through hole 101a of the polishing pad 101 as a member different from the support member 254, and the thickness of the polishing pad 101 is larger than the depth h of the through hole 101a. Is also big. In FIG. 18 (d), the portion of the support member 254 serving as the cathode that forms the through hole 101a together with the polishing pad 101 is recessed, and the thickness of the polishing pad 101 is smaller than the depth h of the through hole 101a. The substantial distance between the surface of the polishing pad 101 and the portion serving as the cathode is larger than the thickness of the polishing pad 101.

Further, as shown in FIG. 19, when the surface of the support member 254 serving as the cathode is flat, the thickness of the polishing pad 101 is equal to the depth of the through hole 101a, and the polishing pad 101 has the outermost surface layer 301 and the base layer. In the case of a multilayer pad having a two-layer structure 302, the handling of the depth h of the through hole 101a differs depending on whether the hole diameter of the through hole 101a is the same or different for each layer 301, 302 of the polishing pad 101. That is, as shown in FIG. 19A, when the through hole 101 a has the same hole diameter D ₁ over the entire polishing pad 101, the depth h of the through hole 101 is the entire thickness of the polishing pad 101. FIG. 19 (b), the as shown in (c), the polishing pad 101 is a two-layer pad, if the hole diameter _{D 2} of the hole diameter _{D 1} and the base layer 302 in the outermost layer 301 of the through-hole 101a is different from _{(D 1} ≠ D ₂ ), the depth h of the through hole 101 a is the same as the thickness of the outermost surface layer 301 of the polishing pad 101, regardless of the thickness of the base layer 302.

As shown in FIG. 19 (d), (e) , the outermost layer 301a, an intermediate layer 301b and the polishing pad 101 of three or more layers of the base layer 302, hole diameter _{D 1} in the outermost surface layer 301a of the through holes 101a are other When the hole diameter is different from the hole diameter D ₃ in the layers 301b and 302 (D ₁ ≠ D ₃ ), the depth h of the through hole 101a is the thickness up to the layer having the same diameter as the hole diameter D ₁ of the through hole of the outermost surface layer 301a. . By defining the depth h of the through hole 101a in this manner, even if the structure of the through hole is different, the electrical resistance between the cathode and the conductive film can be made substantially equal by making the virtual filling rate the same. .

In that case, the pore size D of the through holes 101a used to calculate the virtual fill rate is hole diameter _{D 1} of the outermost layer 301 or 301a. When the polishing pad has a multilayer structure, for example, the lower layer is formed of a relatively soft material and the upper layer is formed of a hard material, so that both the uniformity of the processing speed of the entire substrate and the local level difference can be solved.

  In the above description, as described for the polishing pad 101 having the outermost surface layer 301 or 301a and the base layer 302, the base when the polishing pad 101 is placed on the support member 254 of the electrolytic composite polishing apparatus, that is, the counter electrode. Since the layer 302 is placed so as to be in contact with the counter electrode 254, the surface of the polishing pad opposite to the surface in contact with the metal film can also be referred to as the surface of the polishing pad on the counter electrode side.

  As shown in FIGS. 20A to 20E, the polishing pad 101 shown in FIGS. 19A to 19E and a conductive closing member 303 are provided to constitute a polishing article. Even if the polishing article is placed so that the closing member 303 faces the support member 254 serving as the cathode, the same effect can be obtained. That is, in this case, the closing member 303 closes the opening on the support member 254 side of the through hole 101 a of the polishing pad 101.

  By the way, including the explanation regarding FIG. 18 to FIG. 20, it is described as “the through hole 101 a of the polishing pad 101”. The through hole 101 a is the side of the polishing pad 101 on the side where the metal film on the substrate surface is polished. This means a hole that penetrates the surface and the surface on the support member 254 side, and the polishing pad 101 is placed on the support member 254 when the electrolytic composite polishing is performed. Needless to say, it functions as a closed hole. When the polishing article is configured as shown in FIG. 20, the through hole 101 a functions as a blocking hole due to the presence of the blocking member 303.

  Further, in a polishing pad having a multilayer structure, if the outermost surface layer in contact with the metal film on the substrate surface is conductive and the lower layer is insulating, the anode of the power source 252 (see FIG. 7) is used. By connecting to the outermost surface layer of the polishing pad instead of the conductive film of the substrate W, power can be supplied to almost the entire surface of the metal film from the outermost surface layer of the polishing pad, so that the contact effect can be reduced and processing is performed rather than providing a power supply electrode separately. The in-plane uniformity of speed is good.

FIG. 21 shows electrolyte flow rate Q = 900 mL / min, polishing pad rotation speed = 75 rpm, distance R ₀ = 240 mm from the rotation center of the polishing pad to the center of the through hole, and distance from the rotation center of the polishing pad to the rotation center of the substrate. R C ₌ 240 mm, the relationship between the thickness and virtual filling ratio of the polishing pad in the case where the substrate diameter D _{W =} 300 mm, the result of calculation by changing the diameter of the through-hole. FIG. 22 shows an electrolyte flow rate Q = 2,000 mL / min, polishing pad rotation speed = 75 rpm, distance R ₀ = 315 mm from the rotation center of the polishing pad to the center of the through hole, and rotation of the substrate from the rotation center of the polishing pad. It is the result of having calculated the relationship between the thickness of the polishing pad and the virtual filling rate when the distance to the center R _C = 315 mm and the substrate diameter D _W = 450 mm and changing the hole diameter of the through hole. In these cases, it is assumed that the thickness of the polishing pad is equal to the depth of the through hole.

  In both cases of FIG. 21 and FIG. 22, the virtual filling rate is about 0.6 or more, as in the case of FIG. The reason why the virtual filling rate is about 0.8 or more is that the diameter of the through hole is about 3 mm or less.

  In addition, from FIGS. 17, 21 and 22, if the depth of the through hole (the thickness of the polishing pad when the surface of the support member serving as the cathode is flat) is 0.5 mm or less, the thickness of the polishing pad is reduced. By doing this, it can be seen that it is advantageous to increase the filling rate by reducing the depth of the through hole. However, if the depth of the through hole is too small, it is difficult to maintain the depth of the through hole due to wear of the polishing pad, and the frequency of replacement of the polishing pad increases. This not only leads to high costs, but also leads to a decrease in throughput because it is necessary to stop the apparatus. Therefore, the through hole depth is preferably 0.1 mm or more.

  Therefore, in the polishing pad having through holes used for electrolytic composite polishing of the metal film on the substrate surface, the diameter of the through holes is in the range of 0.1 mm to 5 mm, and the depth of the through holes is 0. It is preferably in the range of 1 mm to 0.5 mm.

  Further, in an electrolytic composite polishing apparatus having a counter electrode (support member) and a polishing pad placed on the counter electrode, which is used for electrolytic composite polishing of a metal film on a substrate surface, the polishing pad The polishing pad has a through hole communicating with the counter electrode from the surface on the substrate processing side, the diameter of the through hole is in the range of 0.1 mm to 5 mm, and the depth of the through hole is 0.1 mm. It is preferred to use a polishing pad that is in the range of ~ 0.5 mm.

  Moreover, even if the polishing pad thickness or the through hole depth is 0.5 mm or more from FIGS. 17, 21, and 22, the larger the polishing pad thickness or the through hole depth, the larger the filling rate. It turns out that it is advantageous to do. This corresponds to the fact that in the second term on the right side of Equation 5, the virtual filling factor increases as D / h (= through hole diameter / through hole depth) decreases.

FIG. 23 shows that the distance R ₀ from the center of rotation of the polishing pad to the center of the through hole is 150 mm to 315 mm and the distance from the center of rotation of the polishing pad to the center of rotation of the substrate when the electrolyte supply amount Q is 100 mL / min. The _RC is 150 mm to 315 mm, the substrate diameter D _W is 100 mm to 450 mm, the polishing pad rotation speed is 25 rpm to 500 rpm, the through hole diameter D is 1 mm to 20 mm, and the polishing pad thickness is changed in the range of 0.5 mm to 5 mm. It is the result of calculating the relationship between the hole diameter of the through hole / the polishing pad thickness and the virtual filling rate. Here, it is assumed that the surface of the support member serving as the cathode is flat and the thickness of the polishing pad is equal to the depth of the through hole.

  From FIG. 23, when the hole diameter / polishing pad thickness is large, especially when the hole diameter is large, the virtual filling rate tends to decrease. Further, when the hole diameter / polishing pad thickness is small and the hole diameter is small, the virtual filling rate increases. Furthermore, if the hole diameter is 5 mm or less and the hole diameter / thickness is 10 or less, the virtual filling rate is about 0.6 or more. If the hole diameter is 3 mm or less and the hole diameter / thickness is 6 or less, the virtual filling rate is about 0.8 or more.

  As described above, the lower limit of the diameter of the through hole is preferably 0.1 mm, more preferably 0.3 mm. Here, when the upper limit of the polishing pad thickness is 5 mm, the lower limit of the hole diameter / thickness is preferably 0.02, more preferably 0.06.

  Therefore, in the polishing pad having a through hole used for electrolytic composite polishing of the metal film on the substrate surface, the diameter of the through hole is in the range of 0.1 mm to 5 mm, and the thickness is 0.5 mm to The hole diameter / thickness is preferably in the range of 0.02 to 10 at 5 mm. More preferably, the through hole has a hole diameter in the range of 0.3 mm to 3 mm, a thickness of 0.5 mm to 5 mm, and a hole diameter / thickness of 0.06 to 6.

  In addition, in a polishing apparatus having a counter electrode (support member) and a polishing pad placed on the counter electrode, which is used for electrolytic composite polishing of a metal film on the substrate surface, the substrate of the polishing pad The polishing pad has a through hole that communicates with the counter electrode from the surface on the side to be processed, the through hole has a hole diameter of 0.1 mm to 5 mm, a thickness of 0.5 mm to 5 mm, and a hole diameter / depth. It is preferable to use a polishing pad having a thickness in the range of 0.02 to 10. It is more preferable to use a polishing pad having a through-hole diameter of 0.3 mm to 3 mm, a thickness of 0.5 mm to 5 mm, and a hole diameter / depth of 0.06 to 6.

Here, looking at Equation 5, since the coefficient C of the second term on the right side is a dimensionless number proportional to the hole diameter D of the through hole as described above, D ² / h (= 2 of the through hole diameter). It can be seen that the virtual filling rate increases as the (multiplier / through hole depth) decreases. FIG. 24 shows the distance R ₀ from the center of rotation of the polishing pad to the center of the through-hole when the electrolyte supply amount Q = 100 mL / min, and the distance from the center of rotation of the polishing pad to the center of rotation of the substrate. The _RC is 150 mm to 315 mm, the substrate diameter D _W is 100 mm to 450 mm, the polishing pad rotation speed is 25 rpm to 500 rpm, the through hole diameter D is 1 mm to 20 mm, and the polishing pad thickness is changed in the range of 0.5 mm to 5 mm. This is a result of calculating the relationship between the square of the diameter of the through hole / the polishing pad thickness and the virtual filling rate. Here, it is assumed that the surface of the support member serving as the cathode is flat and the polishing pad thickness is equal to the through hole depth.

  From FIG. 24, when the square of the hole diameter / thickness of the polishing pad is large, especially when the hole diameter is large, the virtual filling rate tends to decrease. Further, when the square of the hole diameter / the polishing pad thickness is small and the hole diameter is small, the virtual filling rate increases. Furthermore, if the hole diameter is 5 mm or less and the square of the hole diameter / the polishing pad thickness is 50 mm or less, the virtual filling rate is about 0.6 or more. If the hole diameter is 3 mm or less and the square of the hole diameter / thickness is 20 mm or less, the virtual filling rate is about 0.8 or more.

  As described above, the lower limit of the diameter of the through hole is preferably 0.1 mm, more preferably 0.3 mm. Here, when the upper limit of the polishing pad thickness is 5 mm, the lower limit of the square of the pore diameter / thickness is the formula of the square of the pore diameter / the polishing pad thickness: the pore diameter = 0.1 mm and the polishing pad thickness = Substituting 5 mm to obtain 0.002, preferably 0.002 mm. Similarly, only the value of the hole diameter is changed to 0.3 mm and substituted to obtain 0.018. 018 mm.

  Therefore, in the polishing pad having a through hole placed on the counter electrode of the electrolytic composite polishing apparatus used for the electrolytic composite polishing of the metal film on the substrate surface, the through hole has a hole diameter of 0.1 mm to 5 mm. Preferably, the thickness is in the range of 0.5 mm to 5 mm, and the square of the hole diameter / thickness is in the range of 0.002 mm to 50 mm. More preferably, the through hole has a hole diameter of 0.3 mm to 3 mm, a thickness of 0.5 mm to 5 mm, and a square of the hole diameter / thickness of 0.018 mm to 18 mm.

  Further, in a polishing apparatus having a counter electrode (support member) and a polishing pad placed on the counter electrode, which is used for electrolytic composite polishing of a metal film on the substrate surface, the substrate of the polishing pad The polishing pad has a through hole communicating with the counter electrode from the surface on the side where the metal is processed, the hole diameter of the through hole is in the range of 0.1 mm to 5 mm, and the thickness is in the range of 0.5 mm to 5 mm, and It is preferable to use a polishing pad having a square of pore diameter / depth of 0.002 mm to 50 mm. Use a polishing pad in which the hole diameter of the through hole is in the range of 0.3 mm to 3 mm, the thickness is in the range of 0.5 mm to 5 mm, and the square / depth of the hole diameter is in the range of 0.018 mm to 18 mm. Is more preferable.

Further, looking at Equation 5, since the second term on the right side is a dimensionless number in which the coefficient C is proportional to the hole diameter D of the through hole as described above, D ² ω ² / h (= 2 of the through hole diameter). It can be seen that the virtual filling rate increases as (multiplier × square of polishing pad angular velocity / through hole depth) decreases. FIG. 25 shows the distance R ₀ from the center of rotation of the polishing pad to the center of the through-hole when the electrolyte supply amount Q is 100 mL / min, and the distance from the center of rotation of the polishing pad to the center of rotation of the substrate. _RC is 150 mm to 315 mm, substrate diameter D _W is 100 mm to 450 mm, polishing pad rotation speed is 25 rpm to 150 rpm, through hole hole diameter D is 1 mm to 20 mm, and polishing pad thickness is changed in the range of 0.5 mm to 5 mm. This is a result of calculating the relationship between the square of the diameter of the through hole × the square of the angular velocity of the polishing pad / the thickness of the polishing pad and the virtual filling rate. Here, it is assumed that the surface of the support member serving as the cathode electrode is flat and the polishing pad thickness is equal to the through-hole depth.

FIG. 25 shows that the virtual filling rate tends to decrease when the square of the hole diameter × the square of the angular velocity of the polishing pad / the polishing pad thickness is large. In particular, when the pore size is large, the tendency to decrease the virtual filling rate is remarkable. Further, when the square of the hole diameter × the square of the angular velocity of the polishing pad / the polishing pad thickness is small and the hole diameter is small, the virtual filling rate increases. If the square of the hole diameter × the square of the angular velocity of the polishing pad / thickness is about 500 mm / s ² or less, the virtual filling rate is about 0.6 or more regardless of the hole diameter. Furthermore, if the square of the hole diameter × the square of the angular velocity of the polishing pad / the polishing pad thickness is about 250 mm / s ² or less, the virtual filling rate is about 0.8 or more regardless of the hole diameter. Further, if the hole diameter is 5 mm or less and the square of the hole diameter × the square of the angular velocity of the polishing pad / thickness is about 10,000 mm / s ² or less, the virtual filling rate is about 0.6 or more. Further, if the hole diameter is 3 mm or less and the square of the hole diameter × the square of the angular velocity of the polishing pad / the polishing pad thickness is about 3,000 mm / s ² or less, the virtual filling rate is about 0.8 or more. .

As described above, the lower limit of the diameter of the through hole is preferably 0.1 mm, more preferably 0.3 mm. Here, when the upper limit of the polishing pad thickness is 5 mm, the square of the hole diameter × the square of the angular velocity of the polishing pad / the lower limit of the thickness is the square of the hole diameter × the square of the angular velocity of the polishing pad / the polishing pad thickness. Substituting the hole diameter = 0.1 mm, the angular velocity = 25 rpm (25 × 2 × π / 60 (rad / s)) and the polishing pad thickness = 5 mm into the above equation, about 0.01 is obtained. It can be said to be 0.01 mm / s ^2, and similarly, since only 0.1 is obtained by substituting only the value of the hole diameter into 0.3 mm to obtain about 0.1, it can be said that 0.1 mm / s ² is more preferable.

Accordingly, an electrolyte is present between the metal film on the substrate surface and the counter electrode, and a voltage is applied between the metal film and the counter electrode, and a through hole is disposed between the substrate and the counter electrode. In the electrolytic composite polishing method of polishing the surface of the metal film by relatively moving the substrate and the polishing pad while pressing the substrate surface against a polishing pad, the through-hole diameter is 0.1 mm to 5 mm, A polishing pad having a thickness of 0.5 mm to 5 mm is used, the polishing pad is rotated about 25 to 150 rpm around the rotation axis, and the square of the diameter of the through hole of the polishing pad × the polishing pad square / the thickness of the polishing pad of the rotational movement angular velocity is preferably rotated in a range of ^{0.01mm / s 2 ~10,000mm / s 2} .

Further, a polishing pad having a through-hole diameter of 0.3 mm to 3 mm or less and a thickness of 0.5 mm to 5 mm is used, and the polishing pad is rotated about 25 to 150 rpm around the rotation axis, and rotating the square × range squared / the thickness of the polishing pad of rotational movement of the angular velocity of 0.1mm ^{/ s 2} ~3,000mm ^/ s 2 of the polishing pad of the diameter of the through hole of the polishing pad Is more preferable.

In addition, an electrolyte is present between the metal film on the substrate surface and the counter electrode, and a voltage is applied between the metal film and the counter electrode, and a through hole is disposed between the substrate and the counter electrode. In the electrolytic composite polishing method for polishing the surface of the metal film by moving the substrate and the polishing pad relative to each other while pressing the substrate surface against the polishing pad, the through-hole diameter is 0.1 mm or more, A polishing pad having a thickness of 0.5 mm to 5 mm is used, the polishing pad is rotated about 25 to 150 rpm around the rotation axis, and the square of the diameter of the through hole of the polishing pad × rotation of the polishing pad square / the thickness of the polishing pad of movement of angular velocity is preferably rotated in a range of 0.01 mm ^/ s 2 500 mm / ^{s 2.}

Further, a polishing pad having a through-hole diameter of 0.3 mm or more and a thickness of 0.5 mm to 5 mm is used, and the polishing pad is rotationally moved about 25 to 150 rpm around a rotation axis, and the polishing is performed. square / the thickness of the polishing pad of the angular velocity squared × the rotational movement of the polishing pad diameter of the through hole of the pad is more preferably rotated in a range of ^{0.1mm / s 2 ~250mm / s 2} .

Further, an electrolytic solution is present between the metal film on the substrate surface and the counter electrode, and the substrate surface is pressed against the polishing pad placed on the counter electrode while applying a voltage between the metal film and the counter electrode. In the electrolytic composite polishing method of polishing the surface of the metal film by relatively moving the substrate and the polishing pad while the polishing pad has a thickness in the range of 0.5 mm to 5 mm, the counter electrode A through hole having a diameter of 0.1 mm to 5 mm in communication with the polishing pad, a rotational speed of the polishing pad in a range of 25 rpm to 150 rpm, and a square of the diameter of the through hole x 2 of the angular velocity of the rotational motion. the depth of multiplication / the through hole is preferably rotated the polishing pad to be in the range of ^{0.01mm / s 2 ~10,000mm / s 2} .

  So far, regarding the relationship between the rotational speed of the polishing pad and the processing speed, based on the knowledge that the processing speed has a strong correlation with the virtual filling ratio calculated from Equation 5, so that the virtual filling ratio is in a suitable range, In other words, by setting the value within the preferred range, a suitable condition is searched by paying attention to the diameter and depth of the through-hole so that the change amount of the processing speed due to the change amount of the rotation speed of the polishing pad is within an allowable range. However, it is considered that there are suitable conditions for the aperture ratio of the through holes. Therefore, the inventors have devised a method for simulating the processing speed from the hole diameter and opening ratio of the through hole, and the hole diameter and opening ratio of the through hole and the processing for processing the copper film (conductive film) on the surface of the semiconductor wafer (substrate). The relationship between the speeds was investigated, and the conditions of the polishing pad opening ratio and polishing pad rotation speed, which were excellent in level difference elimination, were derived.

  Here, the processing mechanism of the electrolytic composite polishing assumed in carrying out the simulation will be described first. Next, a method for simulating the machining speed based on the assumed machining mechanism will be described.

As the processing mechanism of the electrolytic composite polishing, two mechanisms of a dissolution type and a film-cutting type are conceivable. The dissolution type is based on dissolving copper (Cu → Cu ²⁺ + 2e) using an oxidizing agent so that the pH and potential are in the active state of copper. The film-cutting type is based on changing the surface of copper into a hardly soluble complex and mechanically removing the hardly soluble complex. Usually, the two occur at the same time, but one is considered dominant. Note that the level difference is eliminated (that is, the level difference between the concave portion and the convex portion on the surface of the conductive film formed on the surface of the substrate). This is realized by electrolytic composite polishing of the outer side (that is, the upper step and the convex). Here, the processing speed was simulated assuming a melting type processing mechanism.

  An image of an assumed machining mechanism is shown in FIG. First, as shown in FIG. 26A, when the surface of the conductive film (copper film) 66 comes into contact with the electrolytic solution 50, BTA (benzotriazole) or the like in the electrolytic solution 50 acts on the surface of the conductive film 66. Thus, the protective film 70 is formed. Next, as shown in FIG. 26B, the protective film 70 is mechanically removed at the non-opening portion (the portion without the through hole 101 a) of the polishing pad 101. Then, as shown in FIG. 26C, the conductive film 66 is dissolved mainly by electrolysis in the through hole 101 a of the polishing pad 101. The protective film 70 is not necessarily completely removed by the non-opening portion of the polishing pad 101 and may remain, but the conductive film 66 is dissolved even if the protective film 70 remains. Note that it is considered that some electrolysis occurs even in the non-opening portion of the polishing pad 101.

  In simulating the processing speed, a processing amount at a certain point on the substrate surface such as a semiconductor wafer was calculated every moment, and the processing amount at the end of processing was divided by the processing time to obtain the processing speed. In order to calculate the processing amount based on the processing mechanism described above, first, the term “protective film amount” is defined as an amount representing the thickness, coverage, etc. of the protective film 70 on the surface of the conductive film 66. It can be easily imagined that when the amount of the protective film is small, the conductive film 66 is easily dissolved, and when the amount of the protective film is large, the conductive film 66 is difficult to dissolve. Therefore, it is considered that the amount of dissolution (dissolution rate) per unit time of the conductive film 66 depends on the amount of the protective film.

  Here, if the amount of the protective film at a certain time / place and the dissolution rate at the protective film amount can be known, the processing amount per minute time (≈dissolution amount) at the time / place can be calculated. Therefore, in the simulation, it is necessary to calculate the dissolution amount while calculating the protective film amount.

  The protective film 70 is formed when the surface of the conductive film 66 is in contact with the electrolytic solution 50, and is removed by contacting the polishing pad 101. Therefore, the protective film amount can be calculated by subtracting the removal amount of the protective film 70 due to contact with the polishing pad 101 from the formation amount of the protective film 70 due to liquid contact. Therefore, if the formation amount and removal amount of the protective film 70 can be estimated by some method, the protective film amount can be calculated.

  Here, when the surface of the conductive film (copper) is directly contacted with the electrolyte without rubbing with the polishing pad, the amount of the protective film increases with the liquid contact time, and gradually approaches a certain amount (saturated protective film amount). It is done. From this, it is considered that the formation amount of the protective film per unit time (protective film formation rate) is a function of the protective film amount, and the function of the following Expression 8 was assumed.

Here, α is a protective film formation rate (unit: [1 / s]), α ₀ is a maximum formation rate (formation rate when the amount of protective film is 0) ([1 / s]), and ζ ^* is a saturated protective film The amount ([−]) and ζ are the protective film amount ([−]).
Therefore, the amount of protective film formation per minute time (Δt) is
Protective film formation amount = αΔt (Formula 9)
It becomes.

  As an example of the protective film formation rate, FIG. 27 shows the relationship between the protective film formation rate and the protective film amount when the maximum formation rate is 100 [1 / s] and the saturation protective film amount is 10, and FIG. The time change of the protective film formation rate and the amount of protective film when not rubbing with a polishing pad is shown.

  On the other hand, the protective film 70 on the surface of the conductive film 66 is removed by coming into contact with the polishing pad 101 while relatively moving. This is considered to be the same as the conventional CMP removal mechanism. Therefore, assuming that the removal amount of the protective film 70 is proportional to the polishing pressure, the relative speed, and the polishing time according to the Preston equation, the protective film removal amount is expressed by the following equation 10.

Protective film removal amount = kpvΔt _p = βvΔt _p (Formula 10)
Here, k Preston coefficient for protective film removal amount ([1 / (psi · m )]), p is polishing pressure ([psi]), v is the relative velocity ([m / s]), Δt p is small Of the time Δt, the contact time with the polishing pad ([s]), β is the protective film removal coefficient ([1 / m]) incorporating the pressure.

From the protective film formation amount and the protective film removal amount assumed as described above, the protective film amount is given by the following equation (11).
Protective film weight = zeta = protective film forming amount - protective film removing amount = αΔt-βvΔt _p (Formula 11)

Even when the surface of the conductive film 66 is in contact with the polishing pad 101 (that is, when the surface of the conductive film 66 is in contact with a portion of the polishing pad 101 that does not have the through-hole 101a), the conductive film 66 is interposed between the polishing pad 101 and the conductive film 66. Since the electrolytic solution 50 may exist, it is considered that the protective film 70 is continuously formed. If the surface of the conductive film 66 is in contact with a polishing pad 101, the protective film forming amount <protective film removal amount, i.e. Arufaderutati <become relationship Betabuiderutati _p, protective film as a result is to be removed.

  Based on the protective film amount calculated by the above method, the dissolution amount of the conductive film 66 per minute time is calculated. At that time, the relationship between the amount of the protective film and the dissolution rate of the conductive film 66 is required. The dissolution rate of the conductive film 66 is large when the amount of the protective film is small, and is small when the amount of the protective film is large. Therefore, the relationship between the amount of the protective film and the copper dissolution rate is assumed by the following equation (12).

Here, R _E is the copper dissolution rate ([nm / s]), R _E0 is the maximum dissolution rate (dissolution rate when the amount of the protective film is 0) ([nm / s]), and ζ ^** is the limit protective film Amount (amount that determines the slope of the dissolution rate) ([−]), R _Em is the minimum dissolution rate ([nm / s]). MAX (a, b) is a function that takes the larger value of a and b.

  In FIG. 29, as an example, the amount of the protective film and the dissolution of the conductive film (copper) when the maximum dissolution rate is 100 [nm / s], the limit protective film amount is 10, and the minimum dissolution rate is 30 [nm / s]. Shows the relationship between rates.

  Here, the dissolution rate of the conductive film is considered to be proportional to the current density on the surface of the conductive film. Even if the amount of the protective film is uniform, the current density is considered to vary depending on the location. Therefore, as shown in FIG. 30 (a), the dissolution rate is strictly even within one through hole 101a of the polishing pad 101. Is not considered uniform. Similarly, in the non-opening portion, it is considered that the dissolution rate decreases as the distance from the through hole 101a increases. However, for simplification, as shown in FIG. 30B, it is assumed that the dissolution rate distribution in the through hole 101a is uniform if the protective film amount is uniform.

  Further, it was assumed that the dissolution rate of the non-opening portion was uniform regardless of the distance from the through hole 101a of the polishing pad 101 if the protective film amount was uniform. Of course, even with the same through-hole 101a, the dissolution rate is not uniform according to Equation 12 unless the protective film amount is uniform. Also, it is considered that the current density distribution depends on the distance from the anode feeding electrode even in the substrate plane. However, in this simulation, this was ignored on the assumption that the film thickness of the conductive film was sufficiently thick.

Here, assuming that the ratio of the dissolution rate of the opening and the dissolution rate of the non-opening is equal if the protective film amount is the same, the dissolution amount of the conductive film is given by the following equation (13).
Dissolution amount of conductive film (copper) = R _E Δt _h + δR _E Δt _p (Formula 13)
Here, Δt _h is the contact time ([s]) of the minute time Δt with the opening of the through-hole 101a of the polishing pad 101, and δ is the dissolution rate ratio (dissolution rate of the non-opening portion / dissolution rate of the opening portion). ) ([-]).

Using the above calculation, the processing amount of the conductive film (copper) per minute is finally
Processing amount of conductive film = Dissolution amount of conductive film = R _E Δt _h + δR _E Δt _p (Formula 14)
It becomes. When this is integrated during processing and divided by the processing time, the processing speed of the conductive film (copper) represented by the following formula 15 is obtained.

  Next, an outline of the simulation program will be described. The machining speed simulation program was created with MATLAB interactive numerical analysis software MATLAB. FIG. 31 shows a flowchart of the main program for calculating the machining speed (machining rate). In the main program, various conditions are set, calculation results are saved, and a hole position matrix generation routine and machining amount calculation routine are called. The hole position matrix generation routine is a routine for calculating the center coordinates of the through hole opened in the polishing pad.

FIG. 32 shows a flowchart of a machining amount calculation routine. In the machining amount calculation routine, first, after initializing various variables and matrices, integration of time is started from time 0.
First, all processing speed calculation positions on the substrate are in contact with through holes (openings) on the polishing pad (that is, whether or not the processing speed calculation positions are present at the positions where the openings are formed). Determine (interference determination). Here, it is assumed that the machining speed calculation position determined to be in contact is in contact with the opening for the minute time Δt. On the other hand, it is assumed that the processing speed calculation position that does not contact the opening of the polishing pad does not contact the opening throughout the minute time Δt.

Next, the relative speed v at all machining speed calculation positions is calculated. The relative speed v is used when calculating the removal amount of the protective film.
Next, the opening contact time, non-opening contact time, and non-opening scratching distance are calculated at all processing speed calculation positions. Here, when contact is made in the interference determination with the previous opening, the opening contact time = Δt, the non-opening contact time = 0, and the non-opening scratching distance = 0. When contact with the previous opening is not detected, the opening contact time = 0, the non-opening contact time = Δt, and the non-opening scratching distance = vΔt.

Then, using the protective film of one preceding time points, performing the calculation of the protective film forming rate α calculated dissolution rate R _E of (Equation 8) and conductive film (12). At that time, make sure that each does not become negative.
Next, the amount of protective film is calculated. First, Equation 11 is calculated. Next, this value is added to the value at the previous time to obtain the protective film amount at this time. At that time, the amount of the protective film should not be a negative value.

Next, the amount of copper dissolved by electrolysis is calculated. First, Equation 13 is calculated. Next, this value is added to the value at the previous time to obtain the integrated dissolution amount up to this time.
Next, the polishing pad and the substrate are each rotated in preparation for the next time calculation. More specifically, the hole position and the machining speed calculation position are rotated by an angle corresponding to each rotation speed.

Next, the time is updated by adding the time. Also, history data is calculated in order to save the history data.
The above is repeated until the set machining time is reached. Then, the amount of copper dissolution accumulated last is taken as the processing amount of the conductive film. The machining speed is calculated by the machining speed calculation main program.

  In order to perform the above-described simulation, it is necessary to determine the seven simulation parameters used in Expressions 8 to 15 by some method. The simulation parameters are summarized in Table 1.

Among these parameters, the dissolution rate ratio and the minimum dissolution rate were determined by experiment, and the dissolution rate ratio was 1/15 and the minimum dissolution rate was 29 nm / s.
The simulation parameters other than the dissolution rate ratio and the minimum dissolution rate were indirectly determined from the experimental results of the dependence of the processing speed on the hole diameter and the opening ratio. The following describes the experimental results, a method for optimizing simulation parameters using the experimental results, and the optimization results.

FIG. 33 shows a through hole depth of 2.6 mm, an aperture ratio of 31.4%, a polishing pad rotation speed of 50 rpm, an electrolyte flow rate of 2000 mL / min, and a distance R _C = 150 mm from the rotation center of the polishing pad to the rotation center of the substrate. The experimental result of the hole diameter dependence of processing speed is shown. In this case, the processing speed decreases almost in proportion to the hole diameter. As a result of linear approximation of the experimental result, a thick line in FIG. 33 was obtained. The approximate expression is as the following Expression 16.
Processing speed (nm / min) = − 2.1 × 10 ¹ × pore diameter (mm) + 1.4 × 10 ³ (Formula 16)

FIG. 34 shows the processing speed at a hole diameter of 5 mm, a depth of 2.6 mm, a polishing pad rotation speed of 50 rpm, an electrolyte flow rate of 2000 mL / min, and a distance R _C = 150 mm from the rotation center of the polishing pad to the rotation center of the substrate. The experimental result of aperture ratio dependence is shown. In this case, the processing speed increases as the aperture ratio increases, but almost reaches a peak at an aperture ratio of 45%. As a result of approximating the experimental result by polynomial approximation, a thick line in FIG. 34 is obtained. The approximate expression is as the following Expression 17.
Processing speed (nm / min) = − 5.0 × 10 ⁻¹ × {aperture ratio (%)} ²
+ 3.9 × 10 ¹ × Aperture ratio (%) + 5.4 × 10 ² (Formula 17)

Next, a method for determining simulation parameters using the above experimental results will be described. The simulation parameters were determined by searching for an objective function defined in FIG. 35, that is, a parameter that minimizes the sum of squares of the distance between the calculated value and the empirical formula. The process of finding the minimum or maximum of the objective function is called optimization.
Objective function = l ₁ ² + l ₂ ² + l ₃ ² + l ₄ ² + l ₅ ² + l ₆ ² + l ₇ ² (Equation 18)

  MATLAB's Optimization Toolbox was used to optimize the simulation parameters. The Optimization Toolbox provides a number of optimization algorithms, but we used the fmincon function to perform constrained minimization. The fmincon function is a function that automatically searches for a parameter that minimizes the objective function under a constraint condition, and uses sequential quadratic programming (SQP method).

In the case of this simulation, the number of parameters to be determined is five excluding the dissolution rate ratio and the minimum dissolution rate determined in the experiment from all seven parameters. However, since each parameter is not independent, one of them is fixed and the number of parameters to be optimized is four. Here, the saturation protective film amount ζ ^* is fixed.

  For the calculation of the objective function, the above empirical formulas (Formula 16 and Formula 17) were used. The calculated value was calculated under the same conditions (excluding the hole diameter and the opening ratio) as the experiment in which the hole diameter dependence and the opening ratio dependence of the processing speed were measured. For the hole diameter dependency, the processing speed was calculated when the hole diameters were 3 mm, 5 mm, 10 mm, and 20 mm, and for the opening ratio dependency, the opening ratios were 20%, 31.4%, and 40%.

  The simulation parameter optimization results are shown in FIG. FIG. 36A shows the hole diameter dependency, and FIG. 36B shows the aperture ratio dependency. In the graph, the triangular mark is the experimental value, the square mark is the average value in the substrate surface of the calculated value, and the diamond mark is the calculated value at the center of the substrate. Thus, the experimental results and the calculation results agreed well with respect to both the hole diameter dependency and the aperture ratio dependency.

FIG. 37 shows a result of simulating the dependency of the processing speed on the aperture ratio. FIG. 37 shows a polishing pad rotation speed of 105 rpm, an electrolyte flow rate of 100 mL / min, a through hole depth of 2.6 mm, and a hole diameter of 1 mm to 20 mm at a distance R _C = 150 mm from the polishing pad rotation center to the substrate rotation center. Is the result of Thus, it has been found that there is an aperture ratio that maximizes the processing speed. This can be explained as follows. In a range where the aperture ratio is small (a range smaller than about 60% in FIG. 37), as the aperture ratio increases, the total area of the apertures (through holes) increases and the amount of copper dissolved by electrolysis increases. , Processing speed increases. However, in a range where the aperture ratio is large (a range larger than about 60% in FIG. 37), the removal amount of the protective film by the polishing pad decreases as the aperture ratio increases, and the amount of protective film increases. Although the total area of the part increases, the machining speed decreases. When the aperture ratio is further increased (in FIG. 37, the aperture ratio is about 80% or more), the ability to remove the protective film by the polishing pad is further reduced, and the average protective film amount is reduced by the conductive film dissolution rate. It approaches or enters a region that is hardly dependent (for example, a region in which the amount of the protective film is larger than 7 in FIG. 29). Therefore, in this region, when the aperture ratio is increased, the total area of the opening is increased, and the processing speed is increased. Also, from FIG. 37, it can be seen that the aperture ratio at which the processing speed is maximum does not depend much on the hole diameter.

FIG. 38 shows a polishing pad rotation speed (TT in the figure) at an electrolyte flow rate of 100 mL / min, a hole diameter of 5 mm, a through hole depth of 2.6 mm, and a distance R _C = 150 mm from the rotation center of the polishing pad to the rotation center of the substrate. (Turntable) is a simulation result from 30 rpm to 150 rpm. From FIG. 38, it can be seen that as the polishing pad rotation speed increases, the peak of the processing speed appears more prominently and the peak position is on the high aperture ratio side.

  Here, the relationship between the dependence of the processing speed on the aperture ratio and the level difference elimination will be considered by taking the case of the polishing pad rotation speed of 75 rpm in FIG. 38 as an example. FIG. 39 shows a simulation result of the opening rate dependence of the processing speed and the average protective film amount when the polishing pad rotational speed is 75 rpm. FIG. 39 shows that the average protective film amount increases as the aperture ratio increases. This can be explained as follows. The average protective film amount is a protective film amount that balances including the minute time during which the protective film formation rate α shown in Expression 8 and the protective film removal rate corresponding to βv in Expression 10 act. As the aperture ratio increases, the non-opening area of the polishing pad decreases as the opening area increases, and the protective film removal rate by the polishing pad decreases. As shown in FIG. 27, the protective film formation rate decreases as the amount of the protective film increases, but the effect of decreasing the protective film removal rate is greater, and the protective film formation rate and the protective film removal rate are balanced. However, it shifts to the larger protective film amount. Therefore, the average protective film amount increases.

  In FIG. 39, in a region where the aperture ratio is less than about 50%, the processing speed increases as the aperture ratio increases. This area will be referred to as area A. Region A is considered to be a region where the protective film formed on the surface of the conductive film is sufficiently removed by the polishing pad. Therefore, when the conductive film surface has irregularities, the convex protective film can be selectively removed by the polishing pad to preferentially dissolve the convex conductive film. Therefore, the uneven step is gradually reduced with the progress of processing, and the step can be eliminated.

  Next, when the aperture ratio exceeds about 50%, the processing speed decreases as the aperture ratio increases. This region (opening ratio: about 50% to 80%) will be referred to as region B. Region B is considered to be a region in which the protective film formation capability is comparable to the protective film removal capability. From FIG. 39, it can be seen that the increase rate of the protective film amount in the region B is clearly larger than that in the region A. In this region B, when the conductive film surface has irregularities, the ability to selectively remove the protective film on the convex portion with the polishing pad is inferior to that of the region A. Therefore, it is considered that the ability to eliminate the step is small compared to the region A.

  For example, when the aperture ratio is about 65% and about 30%, the processing speed itself shows almost the same value, but when the aperture ratio is about 30%, the convex portion is processed preferentially. On the other hand, in the case of about 65%, as a result of processing the concave portion, it is considered that the step in the region B is more difficult to eliminate than the region A.

  Next, when the aperture ratio exceeds about 80%, the processing speed increases as the aperture ratio increases. This area will be referred to as area C. Region C is considered to be a region in which the protective film forming ability is larger than the protective film removing ability. In this region C, the average protective film amount approaches or enters a region where the dissolution rate of the conductive film hardly depends on the protective film amount. It is considered that the ability to solve the problem is extremely small.

  As described above, it is necessary to perform processing in the region A or the region B in order to obtain the step resolution. Further, it is desirable to perform processing in the region A. Here, referring back to FIG. 38, it can be seen that the range of each of the regions A to C varies depending on the rotation speed of the polishing pad. As the polishing pad rotation speed increases, the range of the region A increases and the boundary with the region B becomes more prominent. Note that, at the polishing pad rotation speed of 30 rpm, the step C has a very small step-resolving capability in the entire aperture ratio range. Therefore, the polishing pad rotation speed is desirably 40 rpm or more.

  As shown in Equation 10, the relative speed between the conductive film and the polishing pad substantially affects the removal of the protective film. However, the relative speed is substantially proportional to the rotation speed of the polishing pad except when the rotation speed of the substrate is extremely high compared to the rotation speed of the polishing pad. Therefore, in this specification, the relative speed is set by a normal polishing apparatus. The polishing pad rotation speed is a parameter. 38 and 39 show simulation results when the distance between the rotation center of the polishing pad and the substrate is 150 mm. When converted to the relative speed at the center of the substrate, the polishing pad rotation speed 40 rpm is about 630 mm / s. Therefore, considering that the rotation speed of the polishing pad is 40 rpm or more and further 150 rpm or less under normal conditions, the operating range is desirably 40 rpm to 150 rpm. At that time, it is desirable that the relative speed between the polishing pad and the substrate at the center of the substrate is 630 mm / s or more.

FIG. 40 shows the relationship between the aperture ratio γ (%) of the through hole that becomes the boundary between the region A and the region B and the polishing pad rotation speed v _p [rpm]. The curve in the figure is an approximate expression shown in the following Expression 19.
v _p = 17 × exp (0.03 × γ) (Equation 19)

  If it is on this curve, that is, if the rotation speed of the polishing pad is equal to or greater than the value indicated by this curve when a certain aperture ratio is selected, the region A is designated. In the range of the polishing pad rotation speed of 40 rpm to 150 rpm, if the aperture ratio is 70% or less, processing can be performed in the region A with good step resolution by appropriately selecting the polishing pad rotation speed. However, if the aperture ratio is too small, the processing speed becomes small as shown in FIGS. Therefore, the aperture ratio is preferably 20% or more.

As described above, the rotational speed of the polishing pad is preferably in the range of 40 rpm to 150 rpm. For example, the polishing pad may be rotated in the range of 51 rpm to 149 rpm, or even in the range of 55 rpm to 145 rpm. Needless to say, good processing is possible. Further, when the rotational speed of the polishing pad of Formula 19 is rewritten by the relative speed v [mm / s] between the polishing pad and the substrate at the center of the substrate, the distance between the rotational center of the polishing pad and the rotational center of the substrate is 150 mm. Equation 20 is obtained.
v = 267 × exp (0.03 × γ) (Equation 20)

In this manner, the shape of the polishing pad can be defined in consideration of operating conditions during polishing (see, for example, FIG. 46).
Moreover, regarding the material used for the polishing pad, any of an independent foamed polyurethane pad, a continuous foamed suede pad, a nonwoven fabric pad, and a pad formed by laminating pads selected from these can be suitably used.

  Next, a specific example of a polishing apparatus or method for performing polishing using a polishing pad having a shape defined by the above-described method will be described.

(First embodiment)
(Substrate processing equipment)
FIG. 41 is a plan view showing an arrangement configuration example of the substrate processing apparatus including the electrolytic composite polishing apparatus according to the present invention.

  As shown in FIG. 41, the substrate processing apparatus 300 includes, for example, a load / unload stage that houses a substrate cassette 204 that stocks a large number of substrates W (see FIG. 2 and the like) that are substrates to be polished. A transport robot 202 having two hands is arranged on the traveling mechanism 200 so as to reach each substrate cassette 204 in the load / unload stage. The traveling mechanism 200 employs a traveling mechanism composed of a linear motor. By adopting a traveling mechanism composed of a linear motor, it is possible to stably and stably carry a substrate having a large diameter and an increased weight. On the extended line of the traveling mechanism 200, an ITM (In-line Thickness Monitor) 224 for measuring the film thickness on the substrate before or after polishing is disposed.

  Two drying units 212 are arranged on the opposite side of the substrate cassette 204 with the traveling mechanism 200 of the transfer robot 202 interposed therebetween. Each drying unit 212 is disposed at a position where the hand of the transfer robot 202 can reach. In addition, a substrate station 206 including four substrate platforms is disposed between the two drying units 212 at a position where the transfer robot 202 can reach.

  A transfer robot 208 is disposed at a position that can reach each drying unit 212 and the substrate station 206. A cleaning unit 214 is disposed at a position where the hand of the transfer robot 208 can reach so as to be adjacent to the drying unit 212. The rotary transporter 210 is disposed at a position where the hand of the transfer robot 208 can be reached, and two electrolytic composite polishing apparatuses 250 according to the embodiment of the present invention are disposed at a position where the rotary transporter 210 and the substrate can be delivered. .

  Each electrolytic composite polishing apparatus 250 includes a head 1, a polishing table 100, a polishing pad 101 (see FIG. 42 and the like), an electrolyte supply nozzle (electrolyte supply unit) 102 that supplies an electrolytic solution to the polishing pad 101, a polishing pad cleaning, and the like. This is a so-called rotary-type electrolytic composite polishing apparatus 250 having a pure water supply nozzle 103 for supplying pure water, a dresser 218 for dressing the polishing pad 101, and a water tank 222 for cleaning the dresser 218. .

(Electrolytic composite polishing equipment, head drive unit)
FIG. 42 is a schematic configuration example diagram of the electrolytic composite polishing apparatus 250.
As shown in FIG. 42, the head 1 is connected to a head drive shaft 11 via a universal joint portion 10, and the head drive shaft 11 is connected to a head air cylinder 111 fixed to a swing arm 110. ing. The head drive shaft 11 is moved up and down by the head air cylinder 111 to raise and lower the entire head 1 and press the substrate W such as a semiconductor wafer held at the lower end of the head body 2 against the polishing table 100. The head air cylinder 111 is connected to the compressed air source 120 via a regulator RE1, and the regulator RE1 can adjust the fluid pressure such as the air pressure of the pressurized air supplied to the head air cylinder 111. . Thereby, the pressing force with which the substrate W presses the polishing pad 101 can be adjusted.

  The head drive shaft 11 is connected to the rotary cylinder 112 via a key (not shown). The rotating cylinder 112 includes a timing pulley 113 on the outer periphery thereof. A head motor 114 as a rotation drive unit is fixed to the swing arm 110, and the timing pulley 113 is connected to a timing pulley 116 provided on the head motor 114 via a timing belt 115. Accordingly, when the head motor 114 is driven to rotate, the rotary cylinder 112 and the head drive shaft 11 rotate together via the timing pulley 116, the timing belt 115, and the timing pulley 113, and the polishing head 1 rotates. The swing arm 110 is supported by a shaft 117 that is fixedly supported by a frame (not shown).

(head)
43 is a cross-sectional view showing a configuration example of the head 1, and FIG. 44 is a bottom view of the head 1 shown in FIG. As shown in FIG. 43, the head 1 includes a cylindrical container-shaped head main body 2 having an accommodating space therein, and a retainer ring 3 fixed to the lower end of the head main body 2. The head body 2 is formed of a material having high strength and rigidity, such as metal and ceramics. The retainer ring 3 is made of a material such as a highly rigid resin such as PPS (polyphenylene sulfide) or ceramics.

  The head body 2 is fitted to a cylindrical container-like housing part 2a, an annular pressure sheet support part 2b fitted inside the cylindrical part of the housing part 2a, and an outer peripheral edge part on the upper surface of the housing part 2a. And an annular seal portion 2c. The lower part of the retainer ring 3 fixed to the lower surface of the housing part 2a of the head body 2 protrudes inward. The retainer ring 3 may be formed integrally with the head body 2.

  The above-described head drive shaft 11 is disposed above the central portion of the housing portion 2 a of the head body 2, and the head body 2 and the head drive shaft 11 are connected by a universal joint portion 10. The universal joint portion 10 includes a spherical bearing mechanism that allows the head body 2 and the head drive shaft 11 to tilt relative to each other, and a rotation transmission mechanism that transmits the rotation of the head drive shaft 11 to the head body 2. 2, the pressing force and the rotational force of the head drive shaft 11 are transmitted to the head body 2 while allowing the tilting of the second drive shaft 11 to the head drive shaft 11.

  The spherical bearing mechanism is interposed between a spherical recess 11a formed at the center of the lower surface of the head drive shaft 11, a spherical recess 2d formed at the center of the upper surface of the housing portion 2a, and both recesses 11a, 2d. The bearing ball 12 is made of a high hardness material such as ceramics. The rotation transmission mechanism includes a drive pin (not shown) fixed to the head drive shaft 11 and a driven pin (not shown) fixed to the housing portion 2a. Even if the head body 2 is tilted, the driven pin and the driving pin are relatively movable in the vertical direction, so that they are engaged with each other by shifting their contact points, and the rotation transmission mechanism rotates the torque of the head driving shaft 11. Is reliably transmitted to the head body 2.

  In the space defined in the head body 2 and the retainer ring 3 fixed to the head body 2 integrally, an elastic pad 4 that contacts the substrate W such as a semiconductor wafer held by the polishing head 1 and an annular shape The holder ring 5 and the substantially disc-shaped chucking plate 6 that supports the elastic pad 4 are accommodated. The elastic pad 4 is sandwiched between a holder ring 5 and a chucking plate 6 fixed to the lower end of the holder ring 5, and covers the lower surface of the chucking plate 6. Thereby, a space is formed between the elastic pad 4 and the chucking plate 6.

  A pressure sheet 7 made of an elastic film is stretched between the holder ring 5 and the head body 2. The pressure sheet 7 is formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, and silicon rubber. The pressure sheet 7 is fixed with one end sandwiched between the housing portion 2a of the head body 2 and the pressure sheet support portion 2b and the other end sandwiched between the upper end portion 5a of the holder ring 5 and the stopper portion 5b. ing. A pressure chamber 21 is formed inside the head main body 2 by the head main body 2, the chucking plate 6, the holder ring 5, and the pressure sheet 7. As shown in FIG. 44, a fluid passage 31 made of a tube, a connector, or the like is extended in the pressure chamber 21, and the pressure chamber 21 is supplied with a compressed air source via a regulator RE2 installed in the fluid passage 31. 120.

  When the pressure sheet 7 is made of an elastic body such as rubber, and the pressure sheet 7 is sandwiched and fixed between the retainer ring 3 and the head main body 2, the elastic deformation of the pressure sheet 7 as an elastic body. Therefore, a preferable plane cannot be obtained on the lower surface of the retainer ring 3. Therefore, in order to prevent this, in this example, the pressure sheet support portion 2b is provided as a separate member, and the pressure sheet 7 is sandwiched between the housing portion 2a of the head body 2 and the pressure sheet support portion 2b. It is fixed.

  Inside a space formed between the elastic pad 4 and the chucking plate 6, a center bag (center contact member) 8 as a contact member that contacts the elastic pad 4 and a ring tube (outer contact member) ) 9 is provided. In this example, as shown in FIGS. 43 and 44, the center bag 8 is disposed at the center of the lower surface of the chucking plate 6, and the ring tube 9 surrounds the periphery of the center bag 8. 8 is arranged outside. The elastic pad 4, the center bag 8, and the ring tube 9 are formed of a rubber material having excellent strength and durability, such as ethylene propylene rubber (EPDM), polyurethane rubber, silicon rubber, etc., like the pressure sheet 7. ing.

  As shown in FIG. 43, the space formed between the chucking plate 6 and the elastic pad 4 is partitioned into a plurality of spaces by the center bag (airbag) 8 and the ring tube (airbag) 9. A pressure chamber (fluid chamber) 22 is formed between the center bag 8 and the ring tube 9, and a pressure chamber (fluid chamber) 23 is formed outside the ring tube 9.

  The center bag 8 includes an elastic film 81 that contacts the upper surface of the elastic pad 4 and a center bag holder (holding part) 82 that detachably holds the elastic film 81. A screw hole 82a is formed in the center bag holder 82, and the center bag 8 is detachably attached to the center portion of the lower surface of the chucking plate 6 by screwing a screw 55 into the screw hole 82a. . A center pressure chamber (fluid chamber) 24 is formed in the center bag 8 by an elastic membrane 81 and a center bag holder 82.

  Similarly, the ring tube 9 includes an elastic film 91 that contacts the upper surface of the elastic pad 4 and a ring tube holder (holding portion) 92 that detachably holds the elastic film 91. A screw hole 92 a is formed in the ring tube holder 92, and the ring tube 9 is detachably attached to the lower surface of the chucking plate 6 by screwing a screw 56 into the screw hole 92 a. An intermediate pressure chamber (fluid chamber) 25 is formed inside the ring tube 9 by an elastic membrane 91 and a ring tube holder 92.

  The pressure chambers 22, 23, the central pressure chamber 24, and the intermediate pressure chamber 25 are in fluid communication with fluid passages 33, 34, 35, 36 made of tubes and connectors, respectively. It is connected to a compressed air source 120 as a supply source via regulators RE3, RE4, RE5, and RE6 installed in the respective fluid passages 33 to 36. The fluid paths 31 and 33 to 36 are connected to the regulators RE2 to RE6 via a rotary joint (not shown) provided at the upper end of the head drive shaft 11.

  In the pressure chamber 21 and the pressure chambers 22 to 25 above the chucking plate 6 described above, a pressurized fluid such as pressurized air or an atmospheric pressure is provided via fluid paths 31 and 33 to 36 communicated with the pressure chambers. And vacuum is supplied. As shown in FIG. 42, the pressures of the pressurized fluid supplied to the respective pressure chambers can be adjusted by the regulators RE2 to RE6 arranged on the fluid paths 31, 33 to 36 of the pressure chambers 21 to 25. . Thereby, the pressure inside each pressure chamber 21-25 can be controlled independently, respectively, or it can be made atmospheric pressure or a vacuum.

  Thus, by making the internal pressures of the pressure chambers 21 to 25 variable independently by the regulators RE2 to RE6, the pressing force for pressing the substrate W against the polishing pad 101 via the elastic pad 4 is applied to the portion of the substrate W. It can be adjusted for each (partition area).

  Further, as shown in FIG. 43, a plurality of convex portions 42 are erected from the chucking plate 6 to the pressure chambers 22 and 23. The tip of the convex portion 42 is exposed to the surface of the elastic pad 4 through the opening 41. A fluid passage 43 extends from the tip surface of the convex portion 42 and is connected to a vacuum source 121 shown in FIG. Thereby, the substrate W can be vacuum-sucked at the tip surface of the convex portion 42 shown in FIG.

(Polishing table, polishing pad)
FIG. 45 is a longitudinal sectional view schematically showing a polishing table 100 of an electrolytic composite polishing apparatus. A disc-shaped support member 254 is fixed to the upper surface of the polishing table 100. The support member 254 is made of a conductive material (metal, alloy, conductive plastic, or the like). The polishing pad 101 is attached to the upper surface of the support member 254, and the upper surface of the polishing pad 101 is a polishing surface. The polishing table 100 is connected to a rotation mechanism (not shown), so that the polishing table 100 can rotate integrally with the support member 254 and the polishing pad 101. The polishing pad 101 is provided with a large number of through holes 101 a that penetrate vertically and reach the support member 254.

  The support member 254 is connected to the cathode of the power source 252 and functions as the first electrode (cathode), that is, the counter electrode of the substrate W. Rollers, brushes, or the like are used as electrical contacts between the wiring extending from the power source 252 and the support member (cathode) 254. For example, as shown in FIG. 45, an electrical contact 262 can be brought into contact with the side surface of the support member 254. The electrical contact 262 is preferably formed of a soft metal having a small specific resistance, such as gold, silver, copper, platinum, or palladium.

  A second electrode (power supply electrode) 264 connected to the anode of the power supply 252 is disposed on the side of the polishing pad 101. The head 1 is configured so that the substrate W comes into contact with the polishing surface with a part of the substrate W protruding to the side of the polishing pad 101, and the lower surface of the substrate W comes into contact with the second electrode 264. It has become. Thereby, a voltage is applied from the second electrode 264 to the conductive film of the substrate W. Then, the support member 254 as a cathode and the conductive film on the substrate W as an anode are electrically connected through an electrolytic solution filled in the through hole 101a of the polishing pad 101. If a part of the retainer ring 3 is made of a conductive substance so that an electrical contact can be made with the substrate W, a voltage can be applied from the second electrode 264 to the conductive film of the substrate W via the retainer ring. is there. The conductive material must be selected in consideration of chemical resistance to the electrolytic solution, alteration due to an electrolytic reaction during electropolishing, and wear resistance when contacting the pad.

  The hole diameter D of the through hole 101a of the polishing pad 101 is 2 mm, and the thickness h is 2.6 mm. Thus, the square of the hole diameter / thickness is set to 1.54 mm. Further, as shown in FIG. 46, a through hole 101a is provided at the apex of a triangular lattice having a pitch P of 3.4 mm, and thereby the aperture ratio of the through hole 101a is set to 31.4%.

  For example, as shown in FIGS. 18B to 18D, unevenness is formed at the position of the through hole 101 a of the polishing pad 101 on the surface on which the polishing pad 101 of the support member 254 is placed, or the through hole When the cathode 254a is disposed in contact with the support member 254 in 101a, the thickness of the polishing pad 101 and the depth h of the through hole 101a are different from each other. In these cases, the value of the depth h of the through hole 101a may be set in the range of 0.5 mm to 5 mm. That is, the hole diameter D of the through hole 101a is 0.1 mm to 5 mm, for example 2 mm, the depth h of the through hole 101a of the polishing pad 101 is 0.5 mm to 5 mm, for example 2.6 mm, and the square of the hole diameter / thickness is 0. It may be set to 0.002 mm to 50 mm, for example, 1.54 mm, and the through hole 101a has an aperture ratio set to 20% to 70%, for example, 31.4%.

  In the above description, “the depth h of the through hole 101a” is described. However, since one of the through holes is closed by, for example, the support member 254 or the cathode 254a, the substantial meaning is “the depth h of the closed hole”. " 18A, when the surface on which the polishing pad 101 of the support member 254 is placed is a flat surface, “the depth h of the through-hole 101a”, that is, in a substantial sense, Needless to say, the depth h ”is the same as the thickness of the polishing pad 101. Therefore, in the embodiment shown in FIG. 18A, the hole diameter D of the through hole 101a, the depth h of the through hole 101a, the square of the hole diameter / thickness, and the aperture ratio are the values shown in FIGS. It can be similar to the value in d).

Moreover, the outermost surface layer of the through-hole 101a using the polishing pad 101 (or the polishing pad 101 and the closing member 303) shown in FIGS. 19A to 19E and 20A to 20E. 0.1mm~5mm pore diameter _{D 1} in 301 or 301a, for example 2 mm, 0.5 mm to 5 mm the depth h of the through hole 101a of the polishing pad 101, for example 2.6 mm, a square / thickness a pore size 0. You may use what set to 002 mm-50 mm, for example, 1.54 mm, and also set the aperture ratio of the through-hole 101a to 20%-70%, for example, 31.4%.

  Here, the treatment of the value of the depth h of the through hole 101a differs depending on whether the hole diameter of the through hole 101a is the same or different for each layer 301 (or 301a, 301b), 302 of the polishing pad 101. This is as described in the description of FIGS. 19 and 20. 19A to 19E, one opening of the through hole 101a of the polishing pad 101 is closed by the support member 254, but in the embodiment of FIGS. One opening of the hole 101a is closed by the closing member 303, and each hole substantially forms a blocking hole.

(Electrolytic composite polishing method)
Next, the polishing process of the electrolytic composite polishing method according to this embodiment will be described.
FIG. 47 is a process diagram of electrolytic composite polishing. First, the film configuration of the substrate W to be polished in this embodiment will be described.

As shown in FIG. 47A, an interlayer insulating film 62 made of an insulating material such as SiO ₂ , SiOF, SiOC, or a low-k material (low dielectric constant insulating film) is formed on the surface of a substrate W made of silicon or the like. Has been. A recess 63 for forming a wiring is formed on the surface of the interlayer insulating film 62. A barrier film 64 made of a material selected from titanium, tantalum, tungsten, ruthenium, and alloys thereof is formed on the surface of the interlayer insulating film 62 including the recess 63 to a thickness of about 10 nm. The barrier film 64 is provided in order to prevent the metal material of the conductive film 66 described below from diffusing into the substrate W and to improve the adhesion between the conductive film 66 and the interlayer insulating film 62.

  On the surface of the barrier film 64, a conductive film 66 made of a conductive metal material selected from aluminum, copper, silver, gold, nickel, tungsten, ruthenium, or an alloy thereof has a thickness of about 500 to 1000 nm. Is formed. In the case where the conductive film 66 is formed by electrolytic plating, a seed film (not shown) serving as an electrode for electrolytic plating is formed on the surface of the barrier film 64. A recess 67 having a height of about 300 nm and a width of about 100 μm is formed on the surface of the conductive film 66 following the recess 63 of the interlayer insulating film 62. In addition, the dimension of the recessed part for wiring formation shown here is shown as an example.

  Since the conductive film 66 filled in the recess 63 of the interlayer insulating film 62 is used as a metal wiring, the conductive film 66 and the barrier film 64 formed outside the recess 63 are unnecessary. Since a plurality of wirings are stacked via the interlayer insulating film 62, the surface of the conductive film 66 in the recess 63 and the surface of the interlayer insulating film 62 are on the same plane with the conductive film 66 and the barrier film 64 removed. The surface of the substrate W needs to be flattened.

Therefore, the excess metal film (conductive film 66 and barrier film 64) is removed by electrolytic composite polishing and planarized. In the electrolytic composite polishing, the polishing pad 101 and the electrolytic solution 50 are present between the metal film on the surface of the substrate W and the counter electrode, a voltage is applied, and the substrate W is pressed against the polishing pad 101 while pressing the surface of the substrate W against the polishing pad 101. The surface of the metal film is polished by moving the polishing pad 101 relative (rotating).
In this embodiment, the case where copper is used as the conductive film 66 will be described. However, examples of the conductive material to be polished include the above-described materials and combinations thereof.

  In the electrolytic composite polishing method of the present embodiment, the conductive film 66 is polished by two stages of bulk polishing and clear polishing according to the thickness of the film as the polishing progresses. Next, a barrier polishing step is performed.

  Specifically, first, as shown in FIGS. 47B and 47C, the conductive film 66 is polished to a predetermined thickness while supplying the electrolytic solution 50 onto the polishing pad 101 as bulk polishing. 47 and FIG. 7, the arrangement relationship of the counter electrode, the polishing pad 101, and the substrate W in the vertical direction is opposite to each other. That is, in the embodiment of the electrolytic composite polishing apparatus shown in FIG. 7, the counter electrode is disposed below as the support member 254, the polishing pad 101 is placed thereon, and the substrate W is mounted on the polishing pad from above the polishing pad. Pressed. 47, the counter electrode is not shown, but in FIG. 47, it is on the upper side of the polishing pad 101, that is, on the opposite side of the conductive film 66 (substrate W) with the polishing pad 101 interposed therebetween.

  The electrolytic composite polishing is performed by utilizing an electrolytic reaction generated by a voltage applied to the conductive film 66. Simultaneously with the electrolytic reaction of the conductive film 66, the protective film forming component and the conductive film contained in the electrolytic solution 50 are used. 66 reacts to form a protective film 70 made of a metal complex on the surface of the conductive film 66. The protective film 70 formed on the upper portion H of the conductive film 66 (outside the recess 67) is removed by contact with the polishing pad 101. As a result, the conductive film 66 of the upper stage portion H is dissolved in the electrolytic solution 50 and removed. On the other hand, the conductive film 66 at the lower stage L (inside the recess 67) is shielded by the protective film 70 and does not dissolve in the electrolytic solution 50. As described above, the step of the conductive film 66 is eliminated and flattened.

  The electrolytic solution 50 includes a corrosion inhibitor such as benzotriazole (BTA) as a protective film forming component that reacts with the metal film. However, with BTA alone, a portion where the protective film 70 is too strong and a portion where the protective film 70 cannot be formed are formed, and it is difficult to ensure the uniformity and stability of the protective film 70. In order to prevent this, the electrolytic solution 50 contains a water-soluble polymer such as ammonium polyacrylate as an auxiliary agent for forming a protective film. As a specific electrolytic solution, for example, 1 mol / L (mol-per-liter) malonic acid + 1.4 mol / L methanesulfonic acid + 0.3 wt% benzotriazole + 0.6 wt% ammonium polyacrylate (average molecular weight: 10,000) +0. A material prepared by adding 0.05 wt% silica abrasive to 7 wt% methanol + 0.05 wt% (surfactant: MX2045L manufactured by Kao) and adjusting the pH to 4.5 with a pH adjuster is suitably used.

  By the way, when electrolytic composite polishing is performed, the rotational speed of the polishing pad 101 may be controlled in order to control step resolution and surface roughness. However, as described above, unless the hole diameter and depth of the through hole 101a of the polishing pad 101 are set within an appropriate range, there is a problem that the processing speed decreases as the rotation speed of the polishing pad 101 increases. Therefore, in this embodiment, polishing is performed with the polishing pad 101 disclosed above.

In FIG. 48, the entire thickness h in which the through-hole 101a shown in FIG. 19 (a) having the hole diameter D ₁ = 2 mm and the aperture ratio 31.4% (triangular lattice pitch 3.4 mm) is 2. As a result of carrying out the electrolytic composite polishing with a 6 mm two-layer pad, and a through hole 101a having a hole diameter D ₁ = 5 mm and an aperture ratio of 31.4% (triangular lattice pitch 8.5 mm), the overall thickness h is The result of carrying out electrolytic composite polishing with a 2.6 mm double-layer pad is shown. The results of electrolytic composite polishing with a two-layer pad having a hole diameter D ₁ = 20 mm, an aperture ratio of 31.4% (triangular lattice pitch 34 mm), and an overall thickness h of 2.6 mm are also shown for reference.

FIG. 48A shows the polishing pad rotational speed dependence of the processing speed when the electrolyte flow rate is 100 mL / min and the distance R _C = 150 mm from the center of rotation of the polishing pad to the center of rotation of the substrate. From FIG. 48 (a), when the hole diameter is 2 mm and the hole diameter is 5 mm, the rotation speed dependency is smaller than when the hole diameter is 20 mm, and when the hole diameter is 2 mm, the rotation speed is higher than that when the hole diameter is 5 mm. It can be seen that the dependency is small.

  FIG. 48B shows the dependency of the processing speed on the polishing pad rotation speed when the electrolytic solution flow rate is 2,000 mL / min. Also in this example, when the hole diameter is 2 mm and the hole diameter is 5 mm, the rotation speed dependency is smaller than that when the hole diameter is 20 mm, and when the hole diameter is 2 mm, the rotation speed dependency is larger than that when the hole diameter is 5 mm. Is small.

In addition, in FIG. 25, the relationship between the virtual filling rate and the square of the diameter of the through hole × the square of the angular velocity of the rotational motion / the depth of the through hole is described. At this time, the rotational speed of the polishing pad is set to 25 rpm to 150 rpm. results of calculation varied between, within the depth of the value of the square / through-hole of the angular velocity of the square × rotational movement of the diameter of the through holes of 0.01mm ^{/ s 2} ~10,000mm ^/ s 2 Thus, if the rotational speed of the polishing pad is changed, the change in the processing speed of the metal film on the substrate surface with respect to the change in the rotational speed of the polishing pad can be suppressed within an allowable value. At this time, the through-hole diameter of the polishing pad 101 is preferably in the range of 0.1 mm to 5 mm. The results shown in FIG. 48 (a) and FIG. 48 (b) demonstrate this through experiments.

In the description of FIG. 40, it has been shown that if the polishing pad rotation speed is selected between 40 rpm and 150 rpm, processing with good level difference elimination is possible. Therefore, for these reasons, during electrolytic polishing, a polishing pad having a diameter of the through hole in the range of 0.1 mm to 5 mm is used, the rotation speed is in the range of 40 rpm to 150 rpm, and the hole diameter of the through hole is Although square / depth of the through hole of the angular velocity squared × the rotational motion is said to preferably rotate the polishing pad 101 to be in the range of 0.01mm ^{/ s 2} ~10,000mm ^/ s 2 In the present embodiment, it is demonstrated that if the electropolishing process is performed under the above conditions, a decrease in the processing speed when the polishing pad rotation speed is increased can be suppressed.

(Polishing pad)
In addition, the following can be employed as the polishing pad.
With respect to the type of the polishing pad, an independent foamed polyurethane pad, a continuous foamed suede pad, a nonwoven fabric pad, and a pad formed by laminating pads selected from these can be mentioned. Moreover, when using the electrolyte solution which does not contain an abrasive grain, you may use the fixed abrasive pad which rebounded the abrasive grain with the binder. As the abrasive grains, cerium oxide (CeO ₂ ), alumina (A 1 ₂ O ₃ ), silicon carbide (SiC), silicon oxide (SiO ₂ ), zirconia (Zr 0 ₂ ), iron oxide (FeO, Fe ₂ O ₃ , Fe ₃ O ₄ ), manganese oxide (MnO ₂ , Mn ₂ O ₃ ), magnesium oxide (MgO), calcium oxide (CaO), barium oxide (BaO), zinc oxide (ZnO), barium carbonate (BaCO ₃ ), calcium carbonate It is possible to employ (CaCO ₃ ), diamond (C), or a composite material thereof. As binders, phenol resin, aminoplast resin, urethane resin, epoxy resin, acrylic resin, acrylated isocyanurate resin, urea-formaldehyde resin, isocyanurate resin, acrylated urethane resin, acrylated epoxy resin, etc. shall be adopted. Is possible. Further, for the purpose of securing a voltage applied to the surface of the conductive film to be polished, a conductive pad having a conductive surface on at least a part of the polishing surface may be used.

  Here, a groove that does not reach the counter electrode (not through the polishing pad) may be formed on the surface of the polishing pad, in addition to the through hole. As for the groove shape, one or more (1) concentric circular grooves, (2) eccentric grooves, (3) polygonal grooves (including lattice grooves), (4) spiral grooves, (5) radiation grooves, (6) parallel A groove, (7) an arc-shaped groove, or a combination thereof may be formed. These groove shapes affect the retention and discharge of the electrolyte. For example, concentric circular grooves and eccentric grooves have an effect that the electrolytic solution is held on the polishing pad because the flow path is closed. On the other hand, the polygonal grooves and the radiating grooves have an effect of accelerating the inflow of the electrolytic solution into the gap between the processed surface of the substrate to be polished and the polishing pad and the discharge of the electrolytic solution out of the polishing pad.

  In order to increase the efficiency of inflow, outflow, and retention of the electrolyte into the gap between the work surface of the substrate and the polishing pad, the groove width, groove pitch, and groove depth are appropriately adjusted in the polishing pad surface, The groove density distribution in the polishing pad may be adjusted. For example, the groove width / depth should be 0.4 mm or more, and the groove pitch should be at least twice the groove width. Considering the flow of the electrolyte, the groove width / depth is more preferably 0.6 mm or more. Also, for the purpose of activating the flow of the electrolyte between the grooves, auxiliary grooves (for example, a plurality of fine grooves formed between concentric circular grooves, a thin groove formed between thick lattice grooves, etc.) ) May be provided. As for the cross-sectional shape of the groove, a V groove may be employed in addition to the square groove and the round groove. When promoting the discharge of the electrolytic solution from the groove, a forward groove inclined downstream in the rotation direction may be formed in consideration of the rotation direction of the polishing table on which the polishing pad is mounted. Conversely, when suppressing discharge of the electrolytic solution from the groove, a reverse groove inclined toward the upstream side in the rotation direction may be formed.

  Further, the shape of the contact surface of the polishing pad with the substrate affects the mechanical removal of the protective film produced by the electrolytic reaction. In order to increase the mechanical action on the contact surface, a sharp contact surface shape is preferable, and examples thereof include a cone shape, a polygonal pyramid shape, and a quadrangular pyramid shape. Here, depending on the object to be polished, if the contact surface shape is too sharp, it may cause scratches and the like. As a measure for avoiding this, a shape with a flat top surface such as a truncated cone or a truncated pyramid may be mentioned. In addition, examples of the shape that further reduces the mechanical action on the contact surface include a cylinder, an elliptic cylinder, and a hemisphere. As the arrangement of these shapes, a regular arrangement such as a lattice, a staggered pattern, or a triangular arrangement, or a random arrangement may be used to eliminate the regularity. Further, a plurality of these shapes may exist in the polishing surface of the polishing pad, and the density distribution may be adjusted.

(Electrolyte)
In addition, the following substances can be employed as substances to be contained in the electrolytic solution. That is, the electrolytic solution is (1) one or more organic acids or salts thereof, (2) one or more strong acids having a sulfonic acid group, (3) a corrosion inhibitor (nitrogen-containing heterocyclic compound), and (4) water-soluble. It is preferable to contain a functional polymer compound, (5) a pH adjuster, (6) abrasive grains, and (7) a surfactant.

Each component contained in the electrolytic solution will be described below.
The organic acid contained in the electrolytic solution needs to form a soluble complex with a metal such as copper to be polished. That is, it is coordinated and dissolved in an aqueous solution, and at least an organic acid needs to be dissolved in water. The organic acid preferably has one or more carboxyl groups (—COOH) in the molecule and one or more hydroxy groups (—OH) together with the carboxyl groups. These organic acids also have a pH buffering action that stabilizes the pH of the electrolytic solution.

  Examples of the carboxylic acid having one carboxyl group that can be preferably used in the electrolyte include formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, and sorbic acid. , Glyoxylic acid, pyruvic acid, levulinic acid, benzoic acid, m-toluic acid, or acetylsalicylic acid. In addition, carboxylic acids having two or more carboxyl groups, which are organic acids that can be preferably used in the electrolyte, include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, maleic acid. Examples thereof include acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, α-ketoglutaric acid, aconitic acid, phthalic acid, and pyromellitic acid.

  In addition, examples of carboxylic acids having at least one hydroxy group together with a carboxyl group, which are organic acids that can be preferably used in an electrolytic solution, include citric acid, glycolic acid, lactic acid, gluconic acid, malic acid, tartaric acid, oxalacetic acid, Examples include salicylic acid, m-hydroxybenzoic acid, gentisic acid, protocatechuic acid, gallic acid, glucuronic acid, sialic acid, or ascorbic acid.

  Examples of these carboxylic acid salts include potassium salts, ammonium salts, alkylamine salts, and hydroxylamine salts. One of these may be added to the electrolytic solution, or a mixture of two or more may be added.

  Among the organic acid groups listed above, those that can be particularly preferably used are malonic acid, succinic acid, citric acid, glycolic acid, lactic acid, gluconic acid, malic acid, or tartaric acid.

  The concentration of the organic acid needs to be equal to or lower than the saturation concentration at the processing temperature. This is because when the saturation concentration is exceeded, the organic acid is precipitated in the electrolytic solution and stable processing cannot be performed. For example, the saturated concentration of maleic acid is 78% by weight (25 ° C.). On the other hand, if the concentration of the organic acid is lower than 0.1%, the supply amount of the organic acid coordinated with the dissolved metal to the surface of the processed part is insufficient, and the processing does not proceed quickly, and the surface of the processed surface Problems such as increased roughness arise. On the other hand, if the concentration is low, the pH buffering action is not sufficient. For the above reasons, the concentration of the organic acid is preferably 0.1 to 80% by weight, and more preferably 1 to 50% by weight.

  The strong acid having a sulfonic acid group contained in the electrolytic solution is for accelerating the etching action and increasing the conductivity of the electrolytic solution so that a current for processing can easily flow. Here, the strong acid means a pKa having a logarithm of the reciprocal of the first dissociation constant indicating the strength of the acid is 3 or less.

  In general, when a strong acid is used, the potential at which copper dissolution begins is low. That is, copper can be processed with a low applied voltage. However, when sulfuric acid, nitric acid or perchloric acid is used, the surface roughness of the processed surface is large due to etching of copper, etc., and phosphoric acid is high in the concentration range where surface gloss can be obtained, so it is necessary for processing copper There are problems such as relatively high voltage. On the other hand, for example, when methanesulfonic acid is used, it has been confirmed that the voltage required for copper processing is low, the processing surface is relatively smooth, and good processing characteristics can be obtained.

  The strong acid having a sulfonic acid group that can be preferably used includes methanesulfonic acid, benzenesulfonic acid, taurine, cysteic acid, alkylbenzenesulfonic acid having 1 to 6 carbon atoms in total, trifluoromethanesulfonic acid, or Examples thereof include fluorosulfonic acid, and one or more of these can be used. The concentration of the strong acid having a sulfonic acid group is preferably 0.1 to 20% by weight, and more preferably 5 to 20% by weight. If the concentration of the strong acid having a sulfonic acid group is too low, the electrical conductivity of the electrolytic solution is lowered, and the current does not flow easily. For this reason, it is preferable that the density | concentration of the strong acid which has a sulfonic acid group is 5 weight% or more. On the other hand, when the concentration of the strong acid having a sulfonic acid group exceeds 20% by weight, the saturated solubility of the organic acid and other components in the electrolytic solution may be reduced, thereby causing precipitation.

  The corrosion inhibitor contained in the electrolytic solution is preferably a nitrogen-containing heterocyclic compound, and forms a compound with a metal such as copper to be processed, and forms a protective film on the metal surface, thereby corroding the metal. It may be a compound known as a compound that suppresses the above. Such a corrosion inhibitor has an effect of promoting flattening in order to suppress excessive processing and prevent dishing and the like.

  Examples of corrosion inhibitors that can be preferably used include benzotriazole and its derivatives, which are conventionally known corrosion inhibitors for copper. In addition to the above-described effects of promoting flattening, indole, 2-ethylimidazole, benzimidazole, 2-mercaptobenzimidazole, 3-amino-1,2,4-triazole, 3-amino- 5-methyl-4H-1,2,4-triazole, 5-amino-1H-tetrazole, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium, 2-methylbenzothiazole, (2-benzothiazolylthio) acetic acid, 3- (2-benzothiazolylthio) propionic acid, 2-mercapto-2-thiazoline, 2-mercaptobenzoxazole, 2,5-dimercapto-1,3,4-thiadiazole, 5-methyl-1,3,4 -Thiadiazole-2-thiol, 5-amino-1,3,4-thiadiazole-2 Thiol, pyridine, phenazine, acridine, 1-hydroxypyridine-2-thione, 2-aminopyridine, 2-aminopyrimidine, trithiocyanuric acid, 2-dibutylamino-4,6-dimercapto-s-triazine, 2-anilino-4 , 6-dimercapto-s-triazine, 6-aminopurine, 6-thioguanine, and combinations thereof.

  When the concentration of the corrosion inhibitor is low, the formation of a protective film becomes insufficient, so that excessive etching occurs in a metal such as copper and a flat processed surface cannot be obtained. On the other hand, even if it is below the saturation solubility, if the concentration of the corrosion inhibitor is too high, the protective surface is excessively formed on the metal surface such as copper, the processing speed is reduced, and the processing surface cannot be uniformly processed. It also causes surface roughness and pits. From the above, the concentration of the corrosion inhibitor is preferably 0.001 to 5% by weight, and more preferably 0.02 to 2% by weight.

  The water-soluble polymer compound contained in the electrolytic solution is effective in forming a protective film together with the corrosion inhibitor, suppressing excessive etching, and flattening the surface of a metal such as copper. In addition, in an electrolytic solution containing a water-soluble polymer compound, the viscosity of the electrolytic solution near the surface of a metal surface (processed surface) such as copper is increased, so that a viscous film is formed on minute concave and convex portions present on the metal surface. A fine surface is polished and polished to obtain a glossy surface.

  Among the water-soluble polymer compounds that can be preferably used, polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, polyethylene glycol, polyisopropylacrylamide, polydimethylacrylamide, One or more types selected from methacrylamide, polymethoxyethylene, polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, and the like can be given.

  As these water-soluble polymer compounds, those having a mass average molecular weight of 1,000 to 500,000 can be used. When the mass average molecular weight exceeds 500,000, it does not dissolve in the electrolyte solution and causes aggregation with the corrosion inhibitor and abrasive grains. When the mass average molecular weight is less than 1000, sufficient protection is provided for metal surfaces such as copper. A film cannot be formed and the planarization performance deteriorates. The mass average molecular weight of the water-soluble polymer compound is preferably 1000 to 100,000, and more preferably 2000 to 25000.

  The concentration of the water-soluble polymer compound is preferably 0.005 to 5% by weight so as not to decrease the processing speed of electrolytic processing (electropolishing) and to suppress excessive processing action. More preferably, it is 2% by weight.

  In order to adjust the pH of the stable electrolyte, a pH adjuster may be added to the electrolyte. As a preferable pH adjuster, alkali is mainly used, and one or more kinds selected from ammonia, alkylamine, hydroxyamine, polyamine, alkali metal compound (for example, potassium hydroxide), and alkaline earth metal compound can be selected. The alkali concentration is generally 0.1 to 20% by weight, and may be appropriately determined depending on the use of the workpiece, the material, the concentration of the organic acid or organic acid salt and strong acid contained, and the pH to be adjusted.

  The pH of a preferable electrolytic solution is 2-10. When the pH of the electrolytic solution is low, corrosion resistance must be taken into consideration when selecting the material for the electropolishing apparatus, and the processing speed increases, while the roughness of the processed surface increases, resulting in excessive etching of metals such as copper. As a result, it becomes difficult to obtain a flat processed surface. When the pH of the electrolytic solution is high, formation of a protective film between the corrosion inhibitor and / or the water-soluble polymer compound and copper may be insufficient, and the planarization action may be insufficient. Therefore, the pH of the electrolytic solution is particularly preferably 3 to 6 when flattening is required with a glossy surface having a high processing speed and excellent surface roughness as in a copper wiring process of a semiconductor substrate.

  Even in the electrolytic composite polishing using the dissolution type mechanism, the electrolytic solution preferably contains abrasive grains. In the cutting type electrolytic composite polishing, the abrasive grains have the effect of mechanically removing metals such as copper, but in the dissolved electrolytic composite polishing, it is formed by a corrosion inhibitor and a water-soluble polymer compound. The effect is to mechanically polish and remove the metal protective film formed. Due to the action of the abrasive grains, an extra protective film is removed, and the processing speed in the electrolytic processing electrolytic polishing is sufficiently increased.

  As an abrasive grain that can be preferably used as an electrolytic solution, one or more kinds selected from alumina, colloidal silica, fumed silica, zirconium oxide, cerium oxide, titanium oxide, and manganese oxide can be exemplified. Among these, alumina, colloidal silica, or fumed silica is preferably used.

  In the case of effectively functioning as electrolytic composite polishing, the concentration of abrasive grains in the electrolytic solution is preferably 10% by weight or less, and in order to exert the effect of abrasive grains, the concentration of abrasive grains is 0.01% by weight. % Or more is necessary. On the other hand, the effect of removing the protective film is effective by using fixed abrasive grains such as a polishing pad even if there are no abrasive grains used dispersed in the electrolyte, and contacting the polishing pad with a metal surface such as copper. Therefore, in such a case, there is no need for abrasive grains in the electrolytic solution, and of course, combined use with fixed abrasive grains is also possible. When using abrasive grains, if the concentration of the abrasive grains exceeds 10% by weight, the aggregation of the abrasive grains increases, and the viscosity of the electrolytic solution may become extremely high. This may hinder electrolytic polishing and cause scratches. For this reason, the optimal abrasive grain concentration is 0.05 to 2% by weight.

  The electrolytic solution may contain a surfactant. The surfactant is not particularly limited as long as it improves the dispersibility of the abrasive grains, and any of cationic, anionic, amphoteric and nonionic can be used. For example, as the anionic surfactant, alkyl ether carboxylate, alkyl sulfate, alkyl sulfonate, amide sulfonate, alkyl allyl sulfonate, naphthalene sulfonate, or a formalin condensate thereof is used. As the cationic surfactant, for example, an aliphatic amine salt or an aliphatic ammonium salt is used. These are appropriately selected and used depending on the concentration of the abrasive grains and the pH of the electrolytic solution. The surfactant is preferably an anionic surfactant, particularly preferably an alkyl sulfonate or a naphthalene sulfonic acid formalin condensate.

  The conductivity of the electrolytic solution is preferably 5 to 200 mS / cm. If the electrolyte conductivity is low, the applied voltage or current must be increased in order to increase the processing speed. In this case, however, the current efficiency decreases due to the generation of oxygen, the generation of pits on the processed surface, and protection. There is an adverse effect on the flattening action due to the destruction of the film. Therefore, it is desired to perform electrolytic processing (electrolytic polishing) at a lower voltage, and for that purpose, the conductivity of the electrolytic solution is preferably 5 to 200 mS / cm.

  Examples of the composition of the electrolyte include (1) 2 to 80% by weight organic acid, (2) 2 to 20% by weight sulfonic acid group strong acid, and (3) 0.01 to 1% by weight corrosion inhibition. An agent, (4) 0.01 to 1% by weight of a water-soluble polymer compound, (5) 0.01 to 2% by weight of abrasive grains, and (6) about 0.01 to 1% by weight of a surfactant. An aqueous solution is provided. The electrolyte solvent is deionized water, preferably ultrapure water.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

It is a graph which shows the relationship between a filling rate (experimental value) and processing speed when changing the rotational speed of a polishing pad. It is a graph which shows the relationship between a filling rate (experimental value) and a processing speed when changing electrolyte supply amount. It is a graph which shows the relationship between a filling rate (experimental value) and processing speed at the time of changing the hole diameter of a through-hole. It is a graph which shows the relationship between a filling rate (experimental value) and processing speed at the time of changing the pressure which presses a board | substrate to a polishing pad. It is a graph which shows the relationship between a filling rate (experimental value) and processing speed in the case of changing the opening rate of a through-hole. The result of investigating the filling rate dependency of the processing speed when the opening rate of the through hole is fixed and the rotation speed of the polishing pad, the amount of electrolyte supplied, the hole diameter of the through hole, and the pressure for pressing the substrate against the polishing pad are changed. It is a graph to show. It is the schematic of the principal part of an electrolytic composite polishing apparatus. It is an image figure which shows the filling condition of the electrolyte solution in the through-hole in area | region _BI , area | region _BII , and area _| region BIII shown in FIG. It is an image figure which shows the filling condition of the electrolyte solution when a polishing pad is rotated in the state where the electrolyte solution is filled in the through hole and the electrolyte solution is not supplied. In copper electrolytic composite polishing, measurement of the filling rate when the aperture ratio of the through hole is fixed and the rotation speed of the polishing pad, the amount of electrolyte supplied, the hole diameter of the through hole, and the pressure for pressing the substrate against the polishing pad are changed. It is a graph which shows the relationship between a result (experimental value) and virtual filling rate (calculated value). It is a graph which shows the relationship between the measurement result of a virtual filling rate and a processing speed. (A) is a graph showing the relationship between the rotational speed of the polishing pad and the processing speed for each hole diameter when the electrolytic solution supply rate is 100 mL / min, and (b) is the polishing when the electrolytic solution supply rate is 100 mL / min. It is a graph which shows the relationship between the rotational speed of a pad, and a virtual filling rate for every hole diameter. (A) is a graph showing the relationship between the rotational speed of the polishing pad and the processing speed for each hole diameter when the electrolyte supply rate is 2,000 mL / min, and (b) is the electrolyte supply rate of 2,000 mL / min. 5 is a graph showing the relationship between the rotational speed of the polishing pad and the virtual filling rate for each hole diameter. It is a graph which shows the result of having calculated the relationship between the polishing pad rotational speed and a virtual filling rate when changing the hole diameter of a through-hole when an electrolyte solution flow rate is 100 mL / min. It is a graph which shows the result of having calculated the relationship between the polishing pad rotational speed and a virtual filling rate when changing the hole diameter of a through-hole at the time of electrolyte solution flow rate being 900 mL / min. It is a graph which shows the result of having calculated the relationship between the polishing pad rotational speed and a virtual filling rate when changing the hole diameter of a through-hole at the time of electrolyte solution flow rate being 2,000 mL / min. It is a graph which shows the result of having calculated the relationship between the polishing pad thickness and a virtual filling rate when changing the hole diameter of a through-hole when an electrolyte solution flow rate is 100 mL / min. It is a figure which shows the relationship between the thickness of the polishing pad in a single layer pad, and each different depth h of a through-hole. It is a figure which shows the relationship between the hole diameter of each different through-hole in a multilayer pad, and the depth h of a through-hole. It is a figure which shows the relationship between the hole diameter of each different through-hole, and the depth h of a through-hole at the time of attaching a closure member to the multilayer pad shown in FIG. 19, and comprising polishing goods. It is a graph which shows the result of having calculated the relationship between the thickness of a polishing pad, and a virtual filling rate when changing the hole diameter of a through-hole at the time of electrolyte solution flow rate being 900 mL / min. It is a graph which shows the result of having calculated the relationship between the thickness of a polishing pad, and a virtual filling rate in case the electrolyte solution flow rate is 2,000 mL / min and changing the hole diameter of the through hole. It is a graph which shows the result of having calculated the relationship between the hole diameter of a through-hole / polishing pad thickness, and a virtual filling rate when changing polishing pad thickness. It is a graph which shows the result of having calculated the relationship between the square of the diameter of a through-hole / polishing pad thickness, and a virtual filling rate when changing the polishing pad thickness. It is a graph which shows the result of having calculated the relationship between the square of the hole diameter of the through-hole x the square of the angular velocity of the polishing pad / the polishing pad thickness and the virtual filling rate when the polishing pad thickness is changed. It is a figure which shows the image of the assumed electrolytic processing mechanism. It is a graph which shows the relationship between a protective film formation rate and the amount of protective films. It is a graph which shows the time change of the protective film formation rate and the amount of protective films when not rubbing with a polishing pad. It is a graph which shows the relationship between the protective film amount and the dissolution rate of a conductive film (copper) when the maximum dissolution rate is 100 [nm / s], the limit protective film amount is 10, and the minimum dissolution rate is 0. It is a figure attached | subjected to description of the simulation of the dissolution rate of an electrically conductive film. It is a flowchart which shows the main program of processing speed (processing rate) calculation. It is a flowchart which shows a processing amount calculation routine. It is a graph which shows the experimental result of the hole diameter dependence of processing speed. It is a graph which shows the experimental result of the opening rate dependence of processing speed. It is a figure which shows the relationship between the hole diameter dependence of processing speed, the opening rate dependence of processing speed, and an objective function. It is a graph which shows the optimization result of a simulation parameter. It is a graph which shows the result of having simulated the opening rate dependence of the processing speed by changing the hole diameter of a through-hole. It is a graph which shows the result of having simulated the opening rate dependence of the processing speed by changing polishing pad rotation speed (it expresses as a TT (turntable) rotation speed in the figure). It is a graph which shows the opening rate dependence of the processing speed and average protective film amount when a polishing pad rotational speed is made constant. FIG. 40 is a graph showing a relationship between an opening ratio (%) of a through hole serving as a boundary between a region A and a region B shown in FIG. 39 and a polishing pad rotation speed [rpm]. It is a top view which shows the example of arrangement | positioning structure of the substrate processing apparatus provided with the electrolytic composite polishing apparatus which concerns on this invention. It is an example of schematic structure of an electrolytic composite polishing apparatus. It is sectional drawing which shows the structural example of a head. It is a bottom view of a head. It is a longitudinal cross-sectional view which shows roughly the grinding | polishing table of an electrolytic composite grinding | polishing apparatus. It is a top view which shows an example of the shape of a polishing pad. It is process drawing of electrolytic composite polishing. (A) is a graph which shows the result of having investigated the polishing pad rotational speed dependence of the processing speed of this invention and a reference example in case an electrolyte flow rate is 100 mL / min, (b) It is a graph which shows the result of having investigated the polishing pad rotational speed dependence of the processing speed of this invention and a reference example in the case of 000 mL / min.

Explanation of symbols

1 Head 50 Electrolyte 62 Insulating film (interlayer insulating film)
64 Barrier film (barrier metal film)
66 Conductive film (metal conductive film)
70 Protective film 100 Polishing table 101 Polishing pad 101a Through hole 102 Electrolyte supply nozzle 250 Electrolytic composite polishing apparatus 252 Power supply 254 Support member (counter electrode)
301, 301a Outermost surface layer 302 Base layer 303 Closure member

Claims (18)

A polishing pad having a through-hole installed on a counter electrode of an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface,
A polishing pad, wherein the through-hole has a hole diameter of 0.1 mm to 5 mm, a thickness of 0.5 mm to 5 mm, and a square of the hole diameter / thickness of 0.002 mm to 50 mm.   The polishing pad according to claim 1, wherein the polishing pad has a multilayer structure.   A base layer having a through hole on the surface of the polishing pad facing the counter electrode; and at least a part of the through hole of the base layer communicates with a surface of the polishing pad that contacts the metal film. The polishing pad according to claim 1, wherein the polishing pad is characterized in that   4. The polishing pad according to claim 2, wherein a layer of the polishing pad that contacts the metal film on the surface of the substrate has conductivity. A polishing pad having a through-hole installed on a counter electrode of an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface,
A polishing pad, wherein the through hole has a diameter of 0.1 mm to 5 mm and a thickness of 0.1 mm to 0.5 mm.   The polishing pad according to any one of claims 1 to 5, wherein an aperture ratio of the through hole of the polishing pad is in a range of 20% to 70%. A polishing article placed on a counter electrode of an electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface,
The polishing pad according to any one of claims 1 to 6,
A conductive closing member provided on the surface of the polishing pad facing the counter electrode;
A polishing article characterized by comprising: An electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface,
A counter electrode;
A polishing pad installed on the counter electrode and having a through hole communicating between the counter electrode and the metal film on the substrate surface;
Electrolytic composite characterized in that the diameter of the through hole is 0.1 mm to 5 mm, the depth of the through hole is 0.5 mm to 5 mm, and the square of the hole diameter / depth is 0.002 mm to 50 mm. Polishing equipment.   9. The electrolytic composite polishing apparatus according to claim 8, wherein the polishing pad has a multilayer structure.   The polishing pad further includes a base layer having a through hole on the surface on the counter electrode side, and at least a part of the through hole of the base layer communicates with a surface that contacts the metal film of the polishing pad. 10. The electrolytic composite polishing apparatus according to claim 8 or 9, wherein:   11. The electrolytic composite polishing apparatus according to claim 9, wherein a layer in contact with the metal film on the surface of the substrate of the polishing pad has conductivity. An electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface,
A counter electrode;
A polishing pad installed on the counter electrode and having a through hole communicating between the counter electrode and the metal film on the substrate surface;
An electrolytic composite polishing apparatus, wherein a diameter of the through hole is in a range of 0.1 mm to 5 mm and a depth of the through hole is in a range of 0.1 mm to 0.5 mm.   The electrolytic composite polishing apparatus according to any one of claims 8 to 12, wherein an opening ratio of the through hole of the polishing pad is in a range of 20% to 70%. An electrolytic composite polishing apparatus used for electrolytic composite polishing of a metal film on a substrate surface,
A counter electrode;
The polishing article according to claim 6, wherein a closing member is disposed on the counter electrode so as to be in contact with the counter electrode;
An electrolytic composite polishing apparatus comprising: The electrolyte solution is present between the metal film on the substrate surface and the counter electrode, and while applying a voltage between the metal film and the counter electrode, the substrate surface is pressed against the polishing pad placed on the counter electrode. In the electrolytic composite polishing method for polishing the surface of the metal film by relatively moving the substrate and the polishing pad,
As the polishing pad, a polishing pad having a through hole with a hole diameter in the range of 0.1 mm to 5 mm communicating between the counter electrode and the metal film on the substrate surface is used.
The rotational speed of the polishing pad is in the range of 40 rpm to 150 rpm, and
Rotating the polishing pad as square / depth of the through hole of the angular velocity squared × the rotational movement of the diameter of the through hole is in the range of 0.01mm ^{/ s 2} ~10,000mm ^/ s 2 An electrolytic composite polishing method characterized by the above. The relationship between the rotational speed v _p (rpm) of the polishing pad and the opening ratio γ (%) of the through hole of the polishing pad is as follows:
v _p ≧ 17 × exp (0.03 × γ)
The electrolytic composite polishing method according to claim 15, wherein:   The electrolytic polishing method according to claim 15 or 16, wherein the polishing pad is the polishing pad according to any one of claims 1 to 6. The electrolyte solution is present between the metal film on the substrate surface and the counter electrode, and while applying a voltage between the metal film and the counter electrode, the substrate surface is pressed against a polishing article installed on the counter electrode. In the electrolytic composite polishing method for polishing the surface of the metal film by relatively moving the substrate and the polishing article,
The polishing article according to claim 6, comprising a polishing pad having a through-hole and a conductive blocking member provided on the surface of the polishing pad on the counter electrode side, as the polishing article.
The rotational speed of the polishing article is in the range of 40 rpm to 150 rpm, and
The polishing pad the abrasive article as square / depth of the through hole of the angular velocity squared × the rotational motion of the diameter of the through hole is in the range of 0.01mm ^{/ s 2} ~10,000mm ^/ s 2 of An electrolytic composite polishing method characterized by rotating the substrate.

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