JP2009125825A - Electrolytic composite polishing method and electrolytic composite polishing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolytic composite polishing method and an electrolytic composite polishing device capable of suppressing the surface roughness of a metallic film after polishing. <P>SOLUTION: An electrolyte 50 exists between the metallic film of a surface on a substrate W and an opposed electrode, a voltage is applied between the metallic film and the opposed electrode, the substrate W and a polishing pad 101 are relatively moved while pressing the surface of the substrate W to the polishing pad 101, and a surface of the metallic film is polished. The electrolytic composite polishing method is characterized in that the electrolyte 50 includes at least a water-soluble polymer compound in the components, and polishing is performed while cooling the surface of the substrate W. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrolytic composite polishing method and an electrolytic composite polishing apparatus, and in particular, an electrolytic composite polishing method for polishing a conductive material (metal) formed on a substrate surface such as a semiconductor wafer by combining an electrochemical action and a mechanical action. And an electrolytic composite polishing apparatus.

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.
In this damascene process, as shown in FIG. 6B, a wiring recess (hereinafter referred to as “concave”) 63 is formed in an insulating film (interlayer insulating film) 62 made of a so-called Low-k material or the like on the substrate. 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, and a metal made of copper, tungsten, or the like is formed on the surface of the barrier film 64. A conductive film (hereinafter referred to as “conductive film”) 66 is formed and a metal conductive material is embedded in the recess 63, and then the excess conductive film 66 and barrier film 64 formed outside the recess 63 are removed. Generally done. Thereby, the unevenness on the substrate is flattened, and the wiring made of the conductive film 66 is formed in the recess.

The removal of the excessive 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, or electrolytic composite polishing.
Among them, as shown in FIG. 6B, the electrolytic composite polishing is performed by supplying an electrolytic solution 50 between the conductive film 66 on the surface of the substrate W and a counter electrode (not shown). The surface of the conductive film 66 is polished by relatively moving the substrate W and the polishing pad 101 while applying a voltage therebetween 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. .

  By applying a voltage between the conductive film 66 and the counter electrode, the conductive film is dissolved electrochemically and the electropolishing proceeds. On the other hand, when there is a protective film forming component in the electrolytic solution 50, polishing is suppressed because the protective film 70 made of a metal complex is formed on the surface of the conductive film 66. If 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, it is formed on the upper step portion (outside the concave portion 67) H of the conductive film 66. The protective film is removed by contact with the polishing pad 101, and the conductive film 66 in that portion 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. By repeating such steps, the surface of the conductive film 66 is flattened.

Here, the protective film forming component for forming the protective film 70 on the conductive film 66 includes a corrosion inhibitor such as benzotriazole (BTA). 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, it is known that the electrolytic solution 50 contains a water-soluble polymer compound such as ammonium polyacrylate as an auxiliary for forming a protective film (see, for example, Patent Document 1).
JP-A-2005-340600

By the way, in recent years, in the wiring formation process of the semiconductor device described above, higher-speed and higher-precision finishing is required.
Here, in the above-described electrolytic composite polishing, the polishing proceeds while repeating the removal and formation of the protective film 70 by the polishing pad 101. As the polishing proceeds, the temperature of the substrate W increases due to frictional heat generated by the polishing. Not only does this occur, but the temperature of the electrolyte also increases. Thereby, there exists a problem that the surface roughness of the metal film after grinding | polishing becomes large. This is because the water-soluble polymer compound forming the protective film 70 is easily dissolved at a high temperature, so that the action as an auxiliary agent for forming the protective film is inhibited, and the protective film 70 becomes uneven and unstable. This is considered to be because. In addition, the water-soluble polymer compound component in the electrolytic solution may be decomposed by increasing the liquid temperature, and the function as an auxiliary for forming a uniform protective film may be weakened.

  Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide an electrolytic composite polishing method and an electrolytic composite polishing apparatus that suppress the surface roughness of a metal film after polishing and have excellent planarization characteristics. And

In order to achieve the above-described object, according to one embodiment of the present invention, an electrolyte 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. An electrolytic composite polishing method for polishing the surface of the metal film by relatively moving the substrate and the polishing pad while pressing the substrate surface against the polishing pad, wherein the electrolyte is at least water-soluble in its components It comprises a polymer compound and is polished while cooling the substrate surface.
According to this configuration, by cooling the substrate surface, it is possible to prevent the temperature of the substrate from rising due to frictional heat generated by polishing, so that the water-soluble polymer compound forming the protective film is dissolved. Can be prevented. Therefore, it is possible to satisfactorily maintain the action as an auxiliary agent for forming a protective film by the water-soluble polymer compound. That is, since the uniformity and stability of the protective film formed by the protective film forming component can be improved, the surface roughness of the metal film can be suppressed.

In a preferred aspect of the present invention, the metal film includes a lower barrier film and an upper conductive film, and the substrate surface is cooled before the barrier film is exposed during polishing of the conductive film. And
According to this configuration, even if the substrate is not cooled from the initial stage of polishing, if the substrate surface is cooled to a predetermined temperature before the barrier film is exposed, the planarization characteristic at the end of polishing is ensured. In addition, the surface roughness of the metal film can be suppressed. Moreover, since the time which cools a board | substrate can be shortened, manufacturing efficiency can be improved.

In a preferred aspect of the present invention, the temperature of the substrate surface is controlled to be higher than a temperature at which the water-soluble polymer compound is aggregated and lower than a temperature at which the water-soluble polymer compound is dissolved.
According to this configuration, the temperature of the substrate surface is controlled to be higher than the temperature at which the water-soluble polymer compound agglomerates and settles, and below the temperature at which the water-soluble polymer compound is dissolved. Can be maintained in a good state, so that the surface roughness of the metal film can be suppressed.
If the substrate surface temperature is too low, the temperature of the electrolyte solution in contact with the substrate is lowered, and as a result, the water-soluble polymer compound is aggregated and precipitated in the electrolyte solution. If the polishing is performed in this state, the surface becomes rough or a problem occurs in the uniformity of polishing. If the temperature of the substrate surface is too high, the water-soluble polymer compound tends to dissolve on the substrate surface, and the formation of the protective film becomes uneven and unstable, resulting in a rough surface.

The prepared electrolyte solution is more likely to coagulate and precipitate as the temperature becomes lower, but it is desirable to maintain the temperature at which the coagulation and precipitation does not occur for about 6 hours after the preparation. The substrate surface temperature can be set using this temperature as a guide.
In addition, in order to maintain the dissolution of the water-soluble polymer compound, the temperature of the electrolytic solution is increased, the frictional heat due to the direct friction between the substrate and the polishing pad, or the frictional heat between the retainer ring of the head component and the polishing pad is indirect. However, the substrate surface temperature may be increased to a temperature at which the water-soluble polymer compound does not dissolve on the substrate surface and the action of the water-soluble polymer compound is good and suppresses surface roughness. Need to keep.

Furthermore, it is preferable to supply the temperature-adjusted electrolytic solution so that the temperature difference between the temperature of the electrolytic solution and the temperature of the substrate surface is within 5 ° C. when the electrolytic solution is supplied to the substrate surface or the polishing pad.
With this configuration, an increase in the surface temperature of the substrate due to contact with the electrolytic solution can be prevented.

In one embodiment of the present invention, 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 while pressing the substrate surface against the polishing pad. An electrolytic composite polishing method for polishing the surface of the metal film by relatively moving the substrate and the polishing pad, wherein the electrolytic solution includes at least a water-soluble polymer compound in its components, and the electrolytic solution It cools and polishes and is characterized by the above-mentioned.
According to this configuration, when the electrolytic solution is cooled, the water-soluble polymer compound contained in the electrolytic solution is stabilized when the protective film is formed. In this state, by reacting the electrolytic solution with the metal film, the action as an auxiliary agent for forming a protective film by the water-soluble polymer compound can be favorably maintained. That is, since the uniformity and stability of the protective film formed by the protective film forming component can be improved, the surface roughness of the metal film can be suppressed.

In a preferred aspect of the present invention, the electrolytic solution is cooled immediately before being supplied to the polishing pad or the substrate surface.
According to this configuration, the cooling of the electrolytic solution is performed immediately before supply to the polishing pad or the substrate surface, thereby preventing the water-soluble polymer compound contained in the electrolytic solution from aggregating and precipitating, and then the water-soluble polymer compound. Since the function as an auxiliary agent for forming the protective film can be maintained in a good state, surface roughness of the metal film can be suppressed.

One embodiment of the present invention includes a polishing pad, a counter electrode facing or close to the substrate, a head that holds a substrate on which a metal film is formed, and a pressing mechanism that presses the substrate held by the head A pressing mechanism that presses the substrate held by the head on the polishing pad, a relative movement mechanism that relatively moves the polishing pad and the head, and an electrolyte supply mechanism that supplies an electrolyte to the metal film on the surface of the substrate And a power supply for applying a voltage between the metal film on the substrate surface and the counter electrode, and temperature control means for cooling the substrate surface.
According to this configuration, it is possible to prevent the water-soluble polymer compound forming the protective film from being dissolved by cooling the substrate surface by the temperature control means. The effect as an auxiliary agent for formation can be maintained satisfactorily. Therefore, surface roughness of the metal film can be suppressed.

In a preferred aspect of the present invention, the head includes a cooling device, and the temperature control means cools the head by the cooling device.
According to this configuration, since the substrate can be directly cooled by cooling the head with the cooling device, the substrate surface can be effectively cooled. As the cooling device, for example, a Peltier element is used, and it is desirable to arrange the cooling unit in the vicinity of the portion that contacts the substrate of the head.

In a preferred aspect of the present invention, the head includes a fluid chamber through which a fluid flows, and the temperature control means cools the fluid in a fluid supply channel or a fluid storage tank to the fluid chamber. And The fluid chamber is not limited to a single chamber (space), and may be a chamber divided into a plurality of chambers. Also, the fluid chamber is not limited to the meaning of a wide space as a chamber, and is a tube suitably disposed as a head cooling. It may be a road.
According to this configuration, the substrate surface can be effectively cooled by supplying the fluid into the fluid chamber while cooling the fluid.

In a preferred aspect of the present invention, the fluid chamber includes a pressure adjusting unit that expands due to an inflow of fluid and presses the substrate against the polishing pad, and the temperature control unit includes the pressurized fluid in the fluid chamber. The pressurized fluid is cooled, or the pressurized fluid is cooled in a supply channel of the pressurized fluid to the fluid chamber or a fluid storage tank.
According to this configuration, the substrate surface can be effectively cooled by cooling the pressurized fluid in the fluid chamber or supplying the pressurized fluid to the fluid chamber while cooling the pressurized fluid.

In a preferred aspect of the present invention, the temperature control means cools a heat medium flowing in a polishing table on which the polishing pad is placed.
According to this configuration, the substrate surface can be cooled from the polishing table side via the electrolytic solution. Further, the temperature control means can be configured easily.

One embodiment of the present invention includes a polishing pad, a head that holds a substrate on which a metal film is formed, a counter electrode that faces or is close to the substrate, and a substrate that is held by the head on the polishing pad. A pressing mechanism for pressing, a relative movement mechanism for relatively moving the polishing pad and the head, an electrolyte supply mechanism for supplying an electrolyte to the metal film on the substrate surface, and a metal film and a counter electrode on the substrate surface A power source for applying a voltage therebetween, and temperature control means for cooling the electrolytic solution.
According to this configuration, when the electrolytic solution is cooled by the temperature control means, the water-soluble polymer compound contained in the electrolytic solution is protected by the water-soluble polymer compound when reacted with the metal film together with the corrosion inhibitor. The action as an auxiliary agent for film formation can be favorably maintained. That is, since the uniformity and stability of the protective film formed by the protective film forming component can be improved, the surface roughness of the metal film can be suppressed.

In a preferred aspect of the present invention, the temperature control means cools the electrolytic solution in the vicinity of the electrolytic solution supply port in the electrolytic solution supply mechanism.
When the electrolytic solution is cooled in the storage tank, the water-soluble polymer compound precipitates in the tank and the supply flow path and cannot be supplied, or deposits on the polishing pad or the counter electrode, so that it cannot reach the substrate. there is a possibility. On the other hand, according to the above configuration, the time for the cooling state can be shortened by cooling the electrolytic solution in the vicinity of the supply port, thereby preventing aggregation of the water-soluble polymer compound contained in the electrolytic solution. it can. Therefore, since the action of the water-soluble polymer compound as an auxiliary agent for forming a protective film can be maintained in a good state, surface roughness of the metal film can be suppressed.

In a preferred aspect of the present invention, the electrolytic solution supply mechanism includes an electrolytic solution supply nozzle that supplies the electrolytic solution to the metal film on the surface of the substrate, and in the vicinity of the electrolytic solution supply port of the electrolytic solution supply nozzle, A heat exchange part having a channel having a surface area larger than that of the electrolyte solution supply channel other than the vicinity of the supply port is formed, and the temperature control means cools the electrolyte solution in the heat exchange unit.
According to this configuration, the heat transfer area can be ensured by forming the heat exchange part in the vicinity of the supply port of the electrolyte supply nozzle by the flow path having a larger surface area than the other part. Therefore, the electrolyte solution flowing through the heat exchange part can be efficiently cooled. In this way, it is possible to prevent the water-soluble polymer compound from aggregating and precipitating during supply, maintaining the electrolyte in a good state, and then supplying the cooled electrolyte to the polishing pad or the metal film on the substrate surface. it can.

In a preferred aspect of the present invention, the electrolytic solution supply mechanism includes an electrolytic solution supply nozzle that supplies the electrolytic solution to the metal film on the surface of the substrate, and the temperature control unit includes the electrolytic solution in the electrolytic solution supply nozzle. It is a Peltier element provided near the supply port.
According to this configuration, by providing a Peltier element in the vicinity of the supply port of the electrolyte supply nozzle, it is possible to prevent aggregation of the water-soluble polymer compound during supply and maintain the electrolyte in a good state before cooling. The electrolyte can be supplied to the polishing pad or the metal film on the substrate surface.

In a preferred aspect of the present invention, the electrolytic solution contains at least a water-soluble polymer compound in its components, and the electrolyte supply mechanism includes a first solution containing the water-soluble polymer compound in the electrolyte solution; The second solution that does not contain an aggregating component in the components is supplied from different flow paths, and the first solution and the second solution are mixed in the vicinity of the supply port, and the temperature control means includes the electrolyte solution Among these, at least the second solution is cooled.
According to this configuration, for example, only the second solution is cooled in advance and mixed with the first solution in the vicinity of the supply port, thereby preventing aggregation of the water-soluble polymer compound and maintaining the electrolyte in a good state. Thus, the electrolytic solution can be efficiently cooled, and the cooled electrolytic solution can be supplied to the polishing pad or the metal film on the substrate surface.

In a preferred aspect of the present invention, the electrolytic solution supply mechanism includes a first electrolytic solution tank that retains the electrolytic solution in a state in which the electrolytic solution is retained above the temperature at which the water-soluble polymer compound is aggregated, and the first electrolytic solution And a second electrolyte tank for storing the electrolyte supplied from the first electrolyte tank between the tank and the supply port, and the electrolyte is supplied to the second electrolyte tank. Preliminary cooling means for cooling to a temperature lower than the temperature of the electrolytic solution supplied from the electrolytic solution tank is provided.
According to this configuration, the second electrolytic solution tank is provided between the first electrolytic solution tank and the supply port, and the temperature is lower in the second electrolytic solution tank than the electrolytic solution supplied from the first electrolytic solution tank. By cooling the electrolytic solution, it is possible to reduce the cooling load during cooling near the supply port. Therefore, it is possible to efficiently cool the electrolytic solution while preventing aggregation of the water-soluble polymer compound and maintaining the electrolytic solution in a good state.

A preferred embodiment of the present invention is characterized by comprising means for cooling the substrate surface in addition to the temperature control means for cooling the electrolytic solution.
According to this configuration, it is possible to prevent the temperature rise of the electrolytic solution after being supplied to the polishing pad or the substrate surface. In addition, the cooling of the substrate surface can improve the uniformity and stability of the protective film. Furthermore, since the substrate surface is cooled, the cooling load in the vicinity of the supply port can be reduced accordingly.

  According to the present invention, since the uniformity and stability of the protective film formed by the protective film forming component can be improved, the surface roughness can be suppressed and the planarization characteristics of the substrate can be improved. Enables high-precision finishing.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
(Substrate processing equipment)
FIG. 1 is a plan view showing an arrangement configuration of a substrate processing apparatus provided with an electrolytic composite polishing apparatus according to the present invention.
As shown in FIG. 1, 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. An ITM (In-line Thickness Monitor) 224 that measures the film thickness on the substrate before or after polishing is disposed on the extension line of the traveling mechanism 200.

  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. 2 and the like), an electrolytic solution supply nozzle (electrolytic solution 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. 2 is a schematic configuration diagram of the electrolytic composite polishing apparatus 250.
As shown in FIG. 2, 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)
3 is a cross-sectional view showing the head 1, and FIG. 4 is a bottom view of the head 1 shown in FIG. As shown in FIG. 3, 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 a peripheral 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 a space defined inside the head main body 2 and the retainer ring 3 fixed integrally to the head main body 2, an elastic pad 4 that abuts on a 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 fluid chamber (pressure chamber) 21 is formed inside the head body 2 by the head body 2, the chucking plate 6, the holder ring 5, and the pressure sheet 7. As shown in FIG. 4, a fluid flow path 31 made of a tube, a connector or the like is extended in the fluid chamber (pressure chamber) 21, and the fluid chamber (pressure chamber) 21 is installed in the fluid flow path 31. The compressed air source 120 is connected via the regulator RE2.

  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.

  A fluid chamber is formed inside the space formed between the elastic pad 4 and the chucking plate 6, and a center bag (center contact member) 8 as a contact member that contacts the elastic pad 4 and a ring. A tube (outer contact member) 9 is provided. In this example, as shown in FIGS. 3 and 4, 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. 3, the space formed between the chucking plate 6 and the elastic pad 4 is divided into a plurality of spaces by the center bag (airbag) 8 and the ring tube (airbag) 9 as fluid chambers. A fluid chamber (pressure chamber) 22 is formed between the center bag 8 and the ring tube 9, and a fluid chamber (pressure 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 fluid chamber (pressure 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 92a 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 92a. An intermediate fluid chamber (pressure chamber) 25 is formed inside the ring tube 9 by an elastic membrane 91 and a ring tube holder 92.

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

  The fluid chambers (pressure chambers) 21 and the fluid chambers (pressure chambers) 22 to 25 above the chucking plate 6 have fluid flow paths 31 and 33 to 36 communicated with the fluid chambers (pressure chambers). A fluid (air or liquid) is supplied via the air, or atmospheric pressure or pressure increase / decrease is performed. As shown in FIG. 2, the regulators RE <b> 2 to RE <b> 6 arranged on the fluid flow paths 31, 33 to 36 of the fluid chambers (pressure chambers) 21 to 25 are used to supply fluids to the respective fluid chambers (pressure chambers). The pressure can be adjusted. Thereby, the internal pressure of each fluid chamber (pressure chamber) 21 to 25 can be controlled independently, or can be reduced to atmospheric pressure or reduced pressure.

In this way, the regulators RE <b> 2 to RE <b> 6 can independently change the pressure inside the fluid chambers (pressure chambers) 21 to 25, thereby pressing the substrate W against the polishing pad 101 via the elastic pad 4. It can be adjusted for each portion (partition area) of the substrate W.
Further, as shown in FIG. 3, a plurality of convex portions 42 are erected from the chucking plate 6 to the fluid chambers (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 flow path 43 extends from the front end surface of the convex portion 42 and is connected to the vacuum source 121 shown in FIG. As a result, the substrate W can be vacuum-sucked at the tip surface of the convex portion 42 shown in FIG.

(Polishing table, polishing pad)
FIG. 5A is a longitudinal sectional view schematically showing a polishing table 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 electrolyte supply nozzle 102 extends along the radial direction of the polishing pad 101. An electrolyte solution supply port 102 a is provided at the tip of the electrolyte solution supply nozzle 102. The supply port 102 a is located above the central portion of the polishing pad 101, and the electrolytic solution is supplied to the central portion of the polishing pad 101 from the electrolytic solution supply source (not shown) through the electrolytic solution supply nozzle 102. When the polishing pad 101 rotates, the electrolytic solution wets and spreads outward, and is filled between the head 1 and the polishing pad 101 and in the plurality of through holes 101 a of the polishing pad 101.

  The support member 254 is connected to the negative electrode of the power source 252 and functions as a first electrode (cathode), that is, a 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. 5A, the 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 positive electrode 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 electrolytic composite polishing, wear resistance when contacting the polishing pad, and the like.

  FIG. 5B is a longitudinal sectional view schematically showing a polishing table of another electrolytic composite polishing apparatus. The support member 254 of the electrolytic composite polishing apparatus 250 basically includes a disk-shaped base 254b and a lid 254a that covers the upper surface of the base 254b. As described above, since the support member 254 functions as a cathode (first electrode), at least one of the lid 254a and the base 254b is made of a conductive material.

  A plurality of communication holes 255 are formed in the same position as the through hole 101 a of the polishing pad 101 in the lid 254 a of the support member 254. Furthermore, a plurality of communication grooves 256 that allow these communication holes 255 to communicate with each other are formed on the lower surface of the lid 254a. Note that a communication groove may be provided on the upper surface of the base 254b. At the center of the polishing pad 101, a first electrolyte receiving port 258A penetrating the polishing pad 101 vertically is formed. Further, the lid 254a has a second electrolyte receiving port 258B at the same position as the first electrolyte receiving port 258A. The second electrolyte receiving port 258B communicates with the plurality of communication grooves 256.

  With such a configuration, the electrolytic solution supplied from the supply port 102a of the electrolytic solution supply nozzle 102 passes through the first electrolytic solution receiving port 258A, the second electrolytic solution receiving port 258B, the communication groove 256, and the communication hole 255 in this order. It flows and reaches the through hole 101a. Then, an upward flow of the electrolyte toward the polishing surface is formed inside the through hole 101a, and the electrolyte is supplied to the polishing surface.

(Cooling means)
Here, as shown in FIGS. 2 and 3, a fluid that connects the fluid chambers (pressure chambers) 22 to 25 described above and regulators RE <b> 2 to 6 that supply fluid into the fluid chambers (pressure chambers) 22 to 25. Cooling means (temperature control means) 28 is provided in the flow paths 33 to 36. The cooling means 28 performs heat exchange with the fluid flowing in the fluid flow paths 33 to 36, thereby cooling the fluid and supplying the fluid into the fluid chambers (pressure chambers) 22 to 25 as a cooling medium. In the polishing step, the surface of the substrate W that is the surface to be polished is cooled. The cooling means may be provided in a fluid storage tank (not shown) that is a supply source of fluid supplied to the fluid chamber.

  Then, the cooling medium supplied into the fluid chambers (pressure chambers) 22 to 25 via the cooling means 28 is heat-exchanged with the back surface of the substrate W with the elastic pad 4 interposed therebetween, thereby cooling the surface of the substrate W (temperature control). ) You can do it. The fluid as a cooling medium supplied to the fluid chamber (pressure chamber) is air (dry air), nitrogen gas, helium gas, alternative chlorofluorocarbon, carbon dioxide or the like as gas, water as liquid, ethylene glycol-water mixed liquid , Alcohol-water mixed solution and the like. The cooling medium is preferably air or water in consideration of cost and environmental aspects. FIG. 2 shows the case where the cooling medium supplied to the fluid chamber is air. However, in the case of a gas that is not air, the compressed air source 120 can be replaced with a compressed gas source corresponding to the gas that serves as the refrigerant. In the case of liquid, the compressed air source 120 may be replaced with a liquid pump corresponding to the liquid supply.

2 and 3 show fluid flow paths 33 to 36 as fluid supply (inflow side) to each fluid chamber (pressure chamber), but flow paths as fluid discharge (outflow side) It is not shown for easy viewing of the drawing. The fluid discharge (outflow side) flow path is preferably provided with a pipe for each fluid chamber (pressure chamber), and may be collectively set for each part of the head. Further, a back pressure valve (not shown) for adjusting the back pressure of the discharge (outflow side) flow path may be installed in each pipe. The fluid chamber is not limited to a single chamber (space), and may be a chamber partitioned into a plurality of chambers. The fluid chamber is not limited to the meaning of a wide space as a chamber, and is suitably arranged for cooling the head. A pipeline may be used.
In order to monitor the surface temperature of the substrate W, it is preferable to provide a non-contact type temperature sensor such as an infrared radiation thermometer. For example, the surface temperature of the substrate W may be measured through a hole provided in the polishing pad 101 with a radiation thermometer embedded in the polishing table 100. By feeding back the information monitored by the temperature sensor, the temperature of the substrate W can be accurately controlled.

(Electrolytic composite polishing method)
Next, the polishing process of the electrolytic composite polishing method according to this embodiment will be described.
FIG. 6 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. 6A, 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 titanium, tantalum, tungsten, ruthenium and / or an alloy thereof is formed to a thickness of about 10 nm on the surface of the interlayer insulating film 62 including the recess 63. 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 such as aluminum, copper, silver, gold, nickel, tungsten, ruthenium or an alloy thereof is formed to a thickness of about 500 to 1000 nm. 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 substrate 50 and the polishing pad 101 are moved relative to each other while a voltage is applied between the metal film on the surface of the substrate W and the counter electrode, and a voltage is applied to press the surface of the substrate W against the polishing pad 101. It is moved (rotated) to polish the surface of the metal film.
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. 6B and 6C, the conductive film 66 is polished to a predetermined thickness while supplying the electrolytic solution 50 onto the polishing pad 101 as bulk polishing.

  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 compound such as ammonium polyacrylate as an auxiliary agent for forming a protective film. As a specific electrolyte, for example, 1 mol / L malonic acid + 1.4 mol / L methanesulfonic acid + 0.3% benzotriazole + 0.6% ammonium polyacrylate (average molecular weight: 10,000) + 0.7% methanol + 0.05% (Surfactant MX2045L manufactured by Kao Corporation) 0.05% silica abrasive is added, and the pH is adjusted to 4.5 with a pH adjuster.

  By the way, as described above, in the electrolytic composite polishing, the temperature of the substrate W increases due to frictional heat generated by the polishing, and the surface roughness of the metal film increases or the level difference elimination performance decreases. This is because the water-soluble polymer compound forming the protective film 70 is easily dissolved at a high temperature, so that the action of the water-soluble polymer compound as an auxiliary agent for forming the protective film is hindered. This is considered to be because it becomes uneven and unstable. As a result, there are problems that the planarization characteristic of the surface of the substrate W is deteriorated, or excessive polishing of the conductive film, so-called dishing occurs. Further, there is a problem that the polishing pad is deformed by heat due to friction between the substrate W and the polishing pad.

  Here, in this embodiment, the polishing is performed while cooling the surface of the substrate W in the polishing step. Specifically, at the start of bulk polishing, the cooling means 28 described above supplies the cooling medium cooled through the regulators RE2-6 (both see FIG. 2 and the like) into the pressure chambers 22-25, and the substrate W Polishing while cooling. As described above, the protective film forming component contained in the electrolytic solution 50 reacts with the conductive film 66 to form the protective film 70, and the protective film 70 is made uniform by the water-soluble polymer compound that is an auxiliary agent for forming the protective film. It has become. By polishing while cooling the substrate W, it becomes possible to prevent the dissolution of the water-soluble polymer compound forming the protective film 70 and to maintain a good effect as an auxiliary agent for forming the protective film 70. Can be made.

Then, as shown in FIG. 6D, as the clear polishing, all the conductive film 66 outside the concave portion 63 is polished to expose the barrier film 64. Note that the cooling of the substrate W is continued even during the clear polishing.
Finally, as shown in FIG. 6E, as barrier polishing, the entire barrier film 64 outside the recess 63 is polished, and a wiring made of the conductive film 66 is formed in the recess 63.

  The inventor of the present application conducted experiments on the influence on the surface roughness and the polishing rate when polishing was performed by changing the temperature of the surface of the substrate W, that is, the surface to be polished. 7 and 8 are graphs normalized by assuming that the surface roughness and the polishing rate are 1 when the temperature of the electrolytic solution is 20 ° C. In this experiment, the temperature of the electrolytic solution 50 supplied onto the substrate W is measured for convenience, but this temperature is equal to the temperature of the surface to be polished on the surface of the substrate W.

  As shown in FIG. 7, it can be seen that as the temperature of the electrolytic solution 50 rises, specifically, when the temperature is higher than 30 ° C., the surface roughness increases. This is because the water-soluble polymer compound forming the protective film is easily dissolved at a high temperature, so that the action of the water-soluble polymer compound as an auxiliary agent for forming the protective film is hindered, and the protective film 70 is not used. This is considered to be uniform. As a result, a portion that is easily polished and a portion that is difficult to be polished are generated on the substrate W, and polishing is performed, so that the surface roughness of the substrate W increases.

  Further, if the temperature at the time of supplying the electrolytic solution 50 is significantly higher than the surface temperature of the substrate W, heat may move from the electrolytic solution 50 to the substrate W, and the surface temperature of the substrate W may increase. Therefore, it is preferable to set the temperature difference between the temperature of the electrolytic solution 50 and the temperature of the surface of the substrate W to 5 ° C. or less when supplied to the polishing pad 101. With this configuration, it is possible to prevent the surface temperature of the substrate W from increasing due to contact with the electrolytic solution 50.

However, if the temperature of the electrolytic solution 50 is too low, there is a problem that the water-soluble polymer compound contained in the electrolytic solution 50 aggregates and precipitates easily. If the polishing is performed in this state, the surface becomes rough or a problem occurs in the uniformity of polishing. If the temperature of the surface of the substrate W is too high, the water-soluble polymer compound is easily dissolved on the surface of the substrate W, and the formation of the protective film becomes uneven and unstable, resulting in increased surface roughness.
Table 1 shows the temperature of the electrolytic solution and the presence or absence of precipitates during the standing time at that temperature.

  As shown in Table 1, when the liquid temperature of the electrolytic solution 50 was 35 ° C., no precipitation occurred even after being left for 24 hours. However, when the liquid temperature of the electrolytic solution 50 was lowered, precipitation occurred in 24 hours at 25 ° C., and precipitation occurred in 8 hours at 17 ° C. From this result, it is difficult to maintain the temperature of the electrolytic solution 50 at a low temperature for a long time. Therefore, it is preferable to set the temperature by directly cooling the surface of the substrate W. The electrolytic solution 50 is more likely to coagulate and precipitate as the temperature becomes lower, but it is desirable to keep the temperature at a temperature at which the coagulation and precipitation does not occur for about 6 hours after preparation. The surface temperature of the substrate W can be set using this temperature as a guide.

  Further, when the temperature of the electrolytic solution 50 is increased in order to maintain the dissolution of the water-soluble polymer compound, the frictional heat due to the direct friction between the substrate W and the polishing pad 101, the retainer ring 3 which is a constituent member of the head 1, and the polishing. The surface temperature of the substrate W may rise indirectly due to frictional heat with the pad 101. Even in this case, it is necessary to keep the surface temperature of the substrate W at a temperature at which the water-soluble polymer compound does not dissolve on the surface of the substrate W and the action of the water-soluble polymer compound is good and the surface roughness is suppressed.

  Therefore, the temperature setting of the substrate W is higher than the temperature at which the water-soluble polymer compound in the electrolytic solution 50 aggregates and precipitates due to the temperature of the substrate W, and forms the protective film 70. Is preferably set to a temperature lower than the melting point, that is, 10 ° C. or higher and 30 ° C. or lower. Furthermore, considering temperature unevenness on the surface of the substrate W, it is preferable to set the temperature to 10 ° C. or more and 25 ° C. or less, more preferably 15 ° C. or more and 25 ° C. or less. Thereby, the effect | action as an auxiliary agent of protective film formation by a water-soluble polymer compound can be maintained in a favorable state.

As described above, in this embodiment, the temperature of the substrate W is controlled by cooling the surface of the substrate W during the polishing step, so that the temperature of the substrate W can be prevented from rising due to frictional heat generated by polishing. It is possible to prevent the water-soluble polymer compound forming the protective film 70 from being dissolved. Therefore, it is possible to satisfactorily maintain the action as an auxiliary agent for forming a protective film by the water-soluble polymer compound. In other words, since the uniformity and stability of the protective film 70 formed by the protective film forming component can be improved, the surface roughness of the metal film is suppressed, the level difference is excellent, and polishing is performed while suppressing dishing. It can be carried out. Therefore, the planarization characteristics of the substrate W can be improved, and high-speed and high-precision finishing is possible.
Further, since the temperature of the substrate W does not increase, the deformation of the polishing pad 101 can be prevented.

  Incidentally, as a polishing method, there is CMP in addition to electrolytic composite polishing. CMP increases the mechanical polishing (surface removal) effect by the relative movement of the polishing agent and the object to be polished (substrate) by the surface chemical action of the polishing agent (abrasive) itself or the action of chemical components contained in the polishing liquid. This is a technique for obtaining a high-speed and smooth polished surface. As described above, it is known that CMP in which polishing is performed mainly with a chemical action is highly temperature dependent, and changes in temperature affect both surface roughness and polishing rate. Further, if the contact pressure between the substrate and the polishing pad is increased in order to improve the polishing rate, dishing occurs on the wiring surface.

  On the other hand, in the electrolytic composite polishing as in the present embodiment, as shown in FIG. 8, even if the temperature is low, the influence on the polishing rate is small, and each temperature shows a value that does not change substantially. In other words, in electrolytic composite polishing, an electrolyte is brought into contact with the conductive film on the surface of the substrate, and by applying a voltage to the conductive film, dissolution, oxidation reaction, etc. occur, while polishing and protective film formation are repeated. Since it progresses, the temperature dependence of the polishing rate is small, and the influence of the applied voltage is considered to be large. Therefore, in the electrolytic composite polishing, the surface roughness can be suppressed by cooling the surface of the substrate and controlling the temperature to be constant, while the surface roughness and the polishing rate are made independent by adjusting the polishing rate with voltage. Can be adjusted. Therefore, high-speed and high-accuracy polishing is possible compared to CMP.

(Second Embodiment)
Next, the structure of the cooling means in 2nd Embodiment which concerns on this invention is demonstrated. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
In the above-described embodiment, as shown in FIGS. 2 and 3, fluid cooling means are provided in the fluid flow paths 33 to 36 that connect the regulators RE <b> 2 to 6 that supply fluid into the fluid chambers (pressure chambers) 22 to 25. Although it was set as the structure, it is good also as a structure which provides the fluid cooling means in the fluid chambers (pressure chamber) 22-25 instead of the fluid flow paths 33-36, for example. As the cooling means, for example, a Peltier device is used as a cooling device, which is preferable because the configuration becomes easy.
In this case, since the pressurized fluid supplied to the fluid chambers (pressure chambers) 22 to 25 can be directly cooled in the fluid chambers (pressure chambers) 22 to 25, the substrate W can be efficiently cooled. .
In addition, when the substrate pressing adjustment mechanism by adjusting the fluid to the fluid chambers (pressure chambers) 22 to 25 is unnecessary, the fluid flow paths 33 to 36 are unnecessary. And the fluid as a refrigerant | coolant can be made unnecessary by arrange | positioning cooling devices, such as a Peltier device suitably.

(Third embodiment)
FIG. 9 is an explanatory diagram of the cooling means of the third embodiment according to the present invention. The cooling means of the electrolytic composite polishing apparatus is for cooling the substrate from the polishing table side, unlike the above-described cooling the substrate from the head side.

  As shown in FIG. 9, the polishing table 100 is formed with a cooling space 80 through which a cooling medium flows. The cooling space 80 is connected to a cooling medium supply source (not shown) via a cooling medium supply pipe 90. The cooling medium is supplied from the cooling medium supply source to the cooling space 80 through the cooling medium supply pipe 90. The cooling space 80, the cooling medium supply pipe 90, and the cooling medium supply source are configured as a cooling unit 95. According to this configuration, since the surface of the substrate W can be cooled from the polishing table 100 via the electrolytic solution, the surface of the substrate W can be efficiently cooled. Further, the configuration can be simplified as compared with the case where the cooling means is provided on the head side.

In addition to the configuration of the cooling means described above, the following modes are also possible.
For example, the substrate may be cooled by providing a cooling means such as a Peltier element on the polishing pad, or by providing a cooling medium supply pipe in the polishing pad so that the cooling medium flows in the polishing pad. Further, the cooling medium may be directly ejected to the polishing pad. In this case, if the supply position of the cooling medium and the electrolytic solution is close, there is a concern that the electrolytic solution may be diluted or the electrolytic solution may be scattered. Therefore, consider the rotation direction of the table, the substrate holder and the supply position of the electrolytic solution. Determine the coolant ejection position.

  It is also possible to cool the substrate by accommodating the entire electrolytic composite polishing apparatus in a temperature-controlled space and cooling the space. In this case, by accommodating the entire electrolytic composite polishing apparatus, the cooling of the electrolytic solution and the cooling of the substrate surface can be performed simultaneously, so that the difference between the supply temperature of the electrolytic solution and the surface temperature of the substrate is also reduced.

Alternatively, a flow path in contact with the retainer ring may be provided, and the substrate may be cooled by flowing a cooled fluid through the flow path to cool the retainer ring.
Moreover, it is good also as a structure which attaches the radiation fin excellent in thermal conductivity to the head side.
In addition, it is also possible to employ | adopt combining the structure mentioned above suitably.

(Fourth embodiment)
Next, based on FIG. 10, 4th Embodiment of this invention is described. FIG. 10 is an enlarged view corresponding to part A of FIG. In the above-described embodiment, polishing is performed while cooling the substrate surface, but this embodiment is different from the first to third embodiments in that the electrolytic solution is cooled.

  As shown in FIG. 10, the electrolyte supply nozzle 310 of the present embodiment has a heat exchange part (temperature control means) 311 formed near the supply port 310a at the tip. The heat exchanging portion 311 is obtained by increasing the heat transfer area by forming the electrolyte supply nozzle 310 in a spiral shape. Cooling means (temperature control means) 312 is provided so as to cover the periphery of the heat exchanging section 311 in which the nozzles are spirally formed. The cooling means 312 has a supply port 313 and a discharge port 314, and is configured such that a cooling medium supplied from a supply source (not shown) circulates. As a result, the electrolytic solution flowing through the heat exchange unit 311 is cooled and supplied to the polishing pad 101.

  As described above, according to the present embodiment, when the electrolytic solution is cooled, the water-soluble polymer compound contained in the electrolytic solution is protected by the water-soluble polymer compound when reacted with the metal film together with the corrosion inhibitor. The action as an auxiliary agent for forming the film 70 can be maintained well. That is, since the uniformity and stability of the protective film 70 formed by the protective film 70 forming component can be improved, the surface roughness of the metal film can be suppressed.

Further, by providing the cooling means 312 in the vicinity of the supply port 310a, it is possible to prevent the water-soluble polymer compound from aggregating and precipitating in the tank for storing the electrolytic solution and the supply flow path, and thus the protective film 70 made of the water-soluble polymer compound. The action as a forming auxiliary agent can be maintained in a good state, and the surface roughness of the metal film can be suppressed.
Furthermore, the heat transfer area can be ensured by forming the electrolyte supply nozzle 310 in a spiral shape and configuring the heat exchange unit 311. And an electrolyte solution can be efficiently cooled by distribute | circulating an electrolyte solution to this heat exchange part 311. FIG. In this embodiment, the electrolyte solution supply nozzle 310 is formed in a spiral shape, but the electrolyte solution supply nozzle 310 has a configuration in which folds are formed in the electrolyte solution supply nozzle or the flow path of the electrolyte solution is finely divided. The design can be changed as appropriate as long as the heat transfer area in the vicinity of the supply port is improved.

(Fifth embodiment)
Next, based on FIG. 11, 5th Embodiment of this invention is described. FIG. 11 is an enlarged view corresponding to part A of FIG.
As shown in FIG. 11, the electrolyte supply nozzle 320 of this embodiment is provided with a plurality of Peltier elements (temperature control means) 321 in the vicinity of the electrolyte supply unit 320a. In FIG. 11, a power supply for energizing the Peltier element is omitted. These Peltier elements 321 are provided so as to cover the periphery of the electrolyte supply nozzle 320 in the vicinity of the supply unit 320a.

  As described above, according to this embodiment, the same effect as that of the fourth embodiment can be obtained, and the shape of the electrolyte supply nozzle 320 can be changed by providing the Peltier element 321 near the supply port 320a of the electrolyte supply nozzle 320. The electrolytic solution can be efficiently cooled without doing so. Therefore, the apparatus cost can be reduced.

(Sixth embodiment)
Next, based on FIG. 12, 6th Embodiment of this invention is described. FIG. 12 is a schematic configuration diagram of an electrolytic solution supply mechanism according to the sixth embodiment.
As shown in FIG. 12, the electrolytic solution supply mechanism 330 of this embodiment includes a first solution tank 331 and a second solution tank 332.

The first solution tank 331 stores a first solution containing a water-soluble polymer compound among the components contained in the electrolytic solution.
The 2nd solution tank 332 stores the 2nd solution which does not contain a water-soluble polymer compound among the components contained in electrolyte solution. The second solution tank 332 is provided with a cooling means (temperature control means) (not shown) so that the second solution stored in the second solution tank 332 is cooled.

  Electrolytic solution supply channels 333 and 334 are connected to the solution tanks 331 and 332, respectively. The electrolyte solution supply channels 333 and 334 merge and extend as a single supply channel 335. Therefore, the solutions supplied from the solution tanks 331 and 332 through the electrolyte supply channels 333 and 334 are mixed in the supply channel 335 and supplied to the polishing pad 101. You may use the mixer for mixing effectively in a junction part. The temperature of the first solution stored in the first solution tank 331 is set to 20 ° C. or higher, preferably 25 ° C. or higher. On the other hand, the temperature of the second solution stored in the second solution tank 332 is 10 to 25 ° C., preferably 15 to 20 ° C. after mixing the first solution and the second solution. Set as follows.

  As described above, according to the present embodiment, the same effect as that of the fourth embodiment is obtained, and only the second solution is cooled in advance and mixed with the first solution by the supply unit 335, so that the water-soluble polymer compound can be obtained. The electrolytic solution can be supplied after preventing aggregation and precipitation and maintaining the electrolytic solution in a good state. In addition, it is good also as a structure which provides the heat exchange part 311 (refer FIG. 10) mentioned above and the Peltier element 321 (refer FIG. 11) in the supply part 335 of this embodiment. Thereby, electrolyte solution can be cooled more effectively.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described based on FIG. FIG. 13 is a schematic configuration diagram of an electrolyte solution supply mechanism according to the seventh embodiment.
As shown in FIG. 13, the electrolyte solution supply mechanism 340 of this embodiment includes a first electrolyte solution tank 341 that stores an electrolyte solution, and a second electrolyte solution tank 342.

The first electrolyte tank 341 stores the electrolyte in a state where the electrolyte is maintained at a temperature at which aggregation does not occur, for example, for about 24 hours, that is, a temperature higher than 25 ° C. (see Table 1). The second electrolytic solution tank 342 is connected to the first electrolytic solution tank 341 via the flow path 343. The second electrolyte tank 342 is provided with pre-cooling means (not shown) and stores the electrolyte in a state where it is held at a temperature that does not aggregate for several hours (for example, 17 ° C. (see Table 1)). The second electrolyte tank 342 is connected to an electrolyte supply nozzle through an electrolyte supply channel 344, and is configured to supply the electrolyte to the polishing pad 101 through the electrolyte supply nozzle. ing.
In the present embodiment, in the vicinity of the electrolyte solution supply port (not shown) from the electrolyte solution supply nozzle to the polishing pad 101, the heat exchange unit 311 (see FIG. 10) or the Peltier element 321 (see FIG. 11) is used. ) Is preferably provided.

  As described above, according to the present embodiment, the same effect as that of the fourth embodiment can be obtained, and the electrolytic solution is maintained at a temperature higher than 25 ° C. in the first electrolytic solution tank 341, and then the second electrolytic solution tank 342. In the inside, the electrolyte can be gradually cooled by cooling to a temperature lower than the temperature held in the first electrolyte tank 341. Therefore, it is possible to reduce the cooling load when cooling is performed near the supply port of the electrolyte supply nozzle. Therefore, the electrolytic solution can be efficiently cooled.

In addition, as a structure which cools electrolyte solution, the structure which cools after supplying electrolyte solution other than the 4th-7th embodiment mentioned above is also possible as follows.
For example, the polishing table 100 is cooled in advance using the configuration of the third embodiment (see FIG. 9) described above. After the polishing table 100 is cooled, an electrolytic solution is supplied onto the polishing pad 101 to cool the electrolytic solution. And you may make it start grinding | polishing, after electrolyte solution is fully cooled. Further, before the polishing, the coolant such as cooled water or nitrogen gas may be directly sprayed onto the polishing table 101 or the polishing pad 102. In this case, if a coolant such as water remains on the surface of the polishing pad 102 at the start of polishing, the concentration of the electrolyte solution becomes thin. Therefore, it is necessary to remove the coolant or replace the electrolyte solution before polishing.

Further, the above-described dresser 218 (see FIG. 1) may be provided with a cooling unit, and the polishing pad 101 may be cooled by the dresser 218. In this case, when used for dressing before the start of polishing or when dressing is performed during polishing (in-situ dress), cooling is possible even during polishing.
In addition, the above-described substrate cooling method and electrolyte solution cooling method can be used in appropriate combination.

The following method can also be used as another electrolytic composite polishing method.
Rather than cooling the substrate from the beginning of polishing, polishing is performed at room temperature in the initial stage of bulk polishing, cooling is started in the middle of polishing, and the substrate may be cooled to a predetermined temperature immediately before the start of clear polishing. In this case, a film thickness sensor such as an eddy current sensor is used to detect that the conductive film has been polished to a predetermined thickness, and cooling is started. Even if comprised in this way, while the planarization characteristic at the time of completion | finish of grinding | polishing can be ensured, the surface roughness of a metal film can be suppressed. Moreover, since the cooling time of a board | substrate can be shortened, manufacturing efficiency can be improved. In addition to the eddy current sensor, a method for detecting that the film thickness has been polished to a predetermined thickness includes an optical monitor, a film thickness measurement using fluorescent X-rays, and a method for monitoring changes in electrical resistance.

(Thickness sensor)
Here, each film thickness measuring method mentioned above is demonstrated.
First, the eddy current sensor method detects the film thickness using a change in the synthetic impedance depending on the film thickness of each part, and applies a high frequency to the conductive film from the eddy current sensor embedded in the polishing table. The film thickness is measured by Therefore, even a thick film such as a conductive film can be measured with high accuracy.

  The measurement by the optical monitor utilizes the fact that the reflection intensity changes due to light interference, and utilizes the fact that the reflected light changes with respect to the film thickness when the residual film thickness becomes a predetermined film thickness or less. Since the change start point varies depending on the wavelength of light used, the wavelength is appropriately selected for the material to be polished. As a measuring method using an optical monitor, there are a method of irradiating measurement light through a through hole of a polishing pad with a light source embedded in the polishing table, and a method of measuring in a state where the substrate is overhanged outside the polishing table.

The measurement by the fluorescent X-ray uses the fact that the intensity of the fluorescent X-ray generated when the measurement object is irradiated with the primary X-ray changes with respect to the film thickness. Measurement is performed by irradiating the conductive film with primary X-rays from an embedded X-ray source.
The measurement of the film thickness by monitoring the voltage / current value during polishing utilizes the fact that the electrical resistance changes according to the film thickness of the conductive film to be measured. In this case, either a method of measuring a change in current at a constant voltage and calculating a film thickness from the electrical resistance, or a method of measuring a change in voltage at a constant current may be used.

Also, when polishing a conductive film on a barrier film or a barrier film on an insulating film, the conductive film is cleared (complete removal of the conductive film in unnecessary portions), that is, exposure of a metal different from the conductive film is detected. In addition to the method described above, the following method may be used as the method for performing the above.
First, there is a method of detecting by a change in the surface temperature of the polishing pad or the surface temperature of the substrate. What is necessary is just to measure the surface temperature of a board | substrate through the measurement of the surface temperature of the polishing pad by a radiation thermometer, or the hole provided in the polishing pad by the radiation thermometer embedded in the table.
In addition, there is a method of detecting by the change of frictional force between the substrate and the polishing pad, change of the polishing table with the polishing pad, change of the drive current of the carrier of the substrate, change of vibration amplitude of specific frequency for substrate carrier Measure.
Also, as a method of changing the surface image of the substrate, the color change of the surface of the substrate through a hole provided in the polishing pad by a chromaticity sensor embedded in the polishing table, or a substrate by an imaging device such as a CCD or CMOS It can be detected by measuring changes in the two-dimensional image of the surface.
Further, there is a method of detecting by measuring a change in a component in the electrolytic solution, for example, a change in a metal ion concentration derived from a conductive film in the electrolytic solution discharged from the polishing table.
Here, the barrier film is Ta, TaN, Ti, TiN, Ru, WN or the like, and the conductive film is a conductive material such as Cu, W, Ni, Au, Ag, Rh, or a barrier film.

The technical scope of the present invention is not limited to the above-described embodiment and its modifications, and includes various modifications made to the above-described embodiment and the like without departing from the spirit of the present invention. . That is, the specific materials and configurations described in the embodiments and the like are merely examples, and can be changed as appropriate.
For example, the cooling means described above may be provided on both the head side and the polishing pad side.
Further, although the rotary type electrolytic composite polishing apparatus has been described as the electrolytic composite polishing apparatus of the present embodiment, it is also possible to use an orbital electrolytic composite polishing apparatus provided with a head having substantially the same diameter as the polishing table. In the orbital method, since the area of the polishing pad is small, the cooling efficiency increases when the cooling means is provided on the polishing pad side.

(Electrolyte)
In addition, the following can be adopted as the electrolytic solution.
The electrolyte 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. Those containing a polymer compound, (5) a pH adjuster, (6) abrasive grains, and (7) a surfactant are preferred.

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. It has been confirmed that when a polishing experiment is performed using an electrolytic solution containing these organic acids, a smooth surface to be polished can be obtained at a relatively high polishing rate.

  The concentration of the organic acid needs to be equal to or lower than the saturation concentration at the polishing temperature. This is because if the saturation concentration is exceeded, the organic acid is precipitated in the electrolytic solution and stable polishing cannot be performed. For example, the saturated concentration of maleic acid is 78% by weight (25 ° C.). On the other hand, when 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 substrate surface is insufficient, and polishing does not proceed quickly, and the surface of the surface to be polished 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 polishing 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 polished with a low applied voltage. However, when sulfuric acid, nitric acid or perchloric acid is used, the surface roughness of the surface to be polished is large due to copper etching, etc., and phosphoric acid has high viscosity in the concentration range where surface gloss can be obtained. There is a problem that the required voltage is relatively high. On the other hand, for example, when methanesulfonic acid is used, it has been confirmed that the voltage required for copper polishing is low, the surface after polishing is relatively smooth, and good polishing 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 polished, 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 polishing 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 polished 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, excessive protection is formed on the metal surface such as copper, the polishing rate is lowered, and uniform polishing is not possible. It also causes sheath 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 (surface to be polished) such as copper is increased, so that the viscosity of the concave and convex portions on the metal surface is reduced. A film is formed, and fine unevenness is 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, in order not to decrease the polishing rate of electrolytic composite polishing and to suppress excessive polishing action, and 0.01 to 2% by weight More preferably.

  In order to adjust the pH of the electrolytic solution, a pH adjusting agent may be added to the electrolytic solution. 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 object to be polished, the material, the concentration of the organic acid or organic acid salt contained, and the strong acid 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 electrolytic composite polishing apparatus, and the polishing rate is increased while the roughness of the surface to be polished is increased. Excessive etching advances and it becomes difficult to obtain a flat polished 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 polishing rate and excellent surface roughness as in the copper wiring process of a semiconductor substrate.

  The electrolyte solution preferably contains abrasive grains. The abrasive grains have an action of mechanically removing metals such as copper, but in the present invention, the abrasive grains also have an action of mechanically removing the protective film formed of the corrosion inhibitor and the water-soluble polymer compound appropriately. is there. By the action of the abrasive grains, an extra protective film is removed, and the polishing rate in the electrolytic composite 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. Electrolysis by depositing abrasive grains on the surface to be polished This may hinder composite 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 conductivity of the electrolyte is low, the applied voltage or current must be increased in order to increase the polishing rate, but in that case, the current efficiency decreases due to oxygen generation, the generation of pits on the surface to be polished, There is an adverse effect on the planarization effect due to the destruction of the protective film. Therefore, it is desired to perform electrolytic composite 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.

(Polishing pad)
In addition, the following can be employed as the polishing pad.
As for the type of the polishing pad, an independent foamed polyurethane pad or a continuous foamed suede pad can be used. 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, the communication groove shape of the polishing pad is one or more of (1) concentric circular grooves, (2) eccentric grooves, (3) polygonal grooves (including lattice grooves), (4) helical grooves, (5) Radiation grooves, (6) parallel grooves, (7) arc-shaped grooves, and combinations 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 radiation grooves have an effect of accelerating the inflow of the electrolyte into the object to be polished and the discharge of the electrolyte out of the polishing pad. In order to increase the efficiency of inflow, outflow, and holding of the electrolyte into the wafer surface, the groove width, groove pitch, and groove depth are appropriately adjusted in the polishing pad surface to adjust the groove density distribution in the polishing pad. You may adjust. 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 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, one or more through holes may be formed on the surface of the polishing pad for the purpose of holding the electrolytic solution.

  Further, the shape of the contact surface of the polishing pad with the wafer affects the mechanical removal of the protective film generated 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, a pyramid shape, and a prism 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. The arrangement of these shapes may be a regular shape such as a lattice, a staggered pattern, or a triangular arrangement, or a random shape in order to eliminate the regularity. A plurality of these shapes may exist in the polishing surface of the polishing pad, and the density distribution may be adjusted.

It is a top view which shows the arrangement configuration of a substrate processing apparatus. It is a schematic block diagram of an electrolytic composite polishing apparatus. It is sectional drawing of a head. It is a bottom view of a head. It is a longitudinal cross-sectional view which shows the principal part of an electrolytic composite polishing apparatus schematically. It is process drawing of electrolytic composite polishing. It is a graph which shows the surface roughness ratio with respect to temperature. It is a graph which shows the polishing rate ratio with respect to temperature. It is explanatory drawing of the cooling means which concerns on 3rd Embodiment of this invention. It is an enlarged view equivalent to the A section of Drawing 2 concerning a 4th embodiment of the present invention. It is an enlarged view equivalent to the A section of Drawing 2 concerning a 5th embodiment of the present invention. It is a schematic block diagram of the electrolyte solution supply mechanism which concerns on 6th Embodiment of this invention. It is a schematic block diagram of the electrolyte solution supply mechanism which concerns on 7th Embodiment of this invention.

Explanation of symbols

W ... Substrate 1 ... Head 2 ... Head body (pressing mechanism)
3. Retainer ring 21, 24, 25 ... Fluid chamber (pressure chamber)
28, 95 ... Cooling means (temperature control means)
31 ... Fluid flow path 50 ... Electrolyte 63 ... Recess 64 ... Barrier film (metal film)
66 ... conductive film (metal film)
67: Recess 101: Polishing pad 102 ... Electrolyte supply nozzle (electrolyte supply mechanism)
114... Head motor (relative movement mechanism)
252 ... Power supply 254 ... Support member

Claims (17)

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 the substrate and the polishing pad are pressed while pressing the substrate surface against the polishing pad. An electrolytic composite polishing method for polishing the surface of the metal film by relatively moving,
The electrolytic solution contains at least a water-soluble polymer compound in its components,
Polishing is performed while cooling the surface of the substrate. The metal film includes a lower barrier film and an upper conductive film,
2. The electrolytic composite polishing method according to claim 1, wherein the substrate surface is cooled before the barrier film is exposed during polishing of the conductive film.   3. The electrolysis according to claim 1, wherein the temperature of the substrate surface is controlled to be higher than a temperature at which the water-soluble polymer compound is aggregated and lower than a temperature at which the water-soluble polymer compound is dissolved. Composite polishing method. 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 the substrate and the polishing pad are pressed while pressing the substrate surface against the polishing pad. An electrolytic composite polishing method for polishing the surface of the metal film by relatively moving,
The electrolytic solution contains at least a water-soluble polymer compound in its components,
An electrolytic composite polishing method, wherein the polishing is performed by cooling the electrolytic solution.   5. The electrolytic composite polishing method according to claim 4, wherein the electrolytic solution is cooled immediately before being supplied to the polishing pad or the substrate surface. A polishing pad;
A head for holding a substrate on which a metal film is formed;
A counter electrode facing or close to the substrate;
A pressing mechanism that presses the substrate held by the head against the polishing pad;
A relative movement mechanism for relatively moving the polishing pad and the head;
An electrolyte supply mechanism for supplying an electrolyte to the metal film on the substrate surface;
A power source for applying a voltage between the metal film on the substrate surface and the counter electrode;
Temperature control means for cooling the substrate surface;
An electrolytic composite polishing apparatus comprising: The head includes a cooling device,
The electrolytic composite polishing apparatus according to claim 6, wherein the temperature control means cools the head by the cooling device. The head includes a fluid chamber through which a fluid flows,
The electrolytic composite polishing apparatus according to claim 6, wherein the temperature control unit cools the fluid in a supply channel of the fluid to the fluid chamber or a fluid storage tank.   The electrolytic composite polishing apparatus according to claim 7, wherein the fluid chamber includes a pressure adjusting unit that expands by inflow of the fluid and presses the substrate against the polishing pad.   10. The electrolytic composite polishing apparatus according to claim 6, wherein the temperature control unit cools a heat medium flowing in a polishing table on which the polishing pad is placed. A polishing pad;
A head for holding a substrate on which a metal film is formed;
A counter electrode facing or close to the substrate;
A pressing mechanism that presses the substrate held by the head against the polishing pad;
A relative movement mechanism for relatively moving the polishing pad and the head;
An electrolyte supply mechanism for supplying an electrolyte to the metal film on the substrate surface;
A power source for applying a voltage between the metal film on the substrate surface and the counter electrode;
Temperature control means for cooling the electrolyte solution;
An electrolytic composite polishing apparatus comprising:   12. The electrolytic composite polishing apparatus according to claim 11, wherein the temperature control means cools the electrolytic solution in the vicinity of the electrolytic solution supply port in the electrolytic solution supply mechanism. The electrolytic solution supply mechanism includes an electrolytic solution supply nozzle that supplies the electrolytic solution to the metal film on the substrate surface,
In the vicinity of the electrolyte solution supply nozzle in the electrolyte solution supply nozzle, a heat exchange part having a channel having a larger surface area than the electrolyte solution supply channel other than the vicinity of the supply port is formed,
The electrolytic composite polishing apparatus according to claim 11, wherein the temperature control unit cools the electrolytic solution in the heat exchange unit. The electrolytic solution supply mechanism includes an electrolytic solution supply nozzle that supplies the electrolytic solution to the metal film on the substrate surface,
13. The electrolytic composite polishing apparatus according to claim 11, wherein the temperature control means is a Peltier element provided near the electrolyte solution supply port of the electrolyte solution supply nozzle. The electrolytic solution contains at least a water-soluble polymer compound in its components,
The electrolyte solution supply mechanism supplies a first solution containing the water-soluble polymer compound in the electrolyte solution and a second solution containing no aggregating component in the components from different flow paths, and a supply port. Mixing the first solution and the second solution in the vicinity;
15. The electrolytic composite polishing apparatus according to claim 11, wherein the temperature control unit cools at least the second solution of the electrolytic solution. The electrolytic solution supply mechanism includes a first electrolytic solution tank that retains the electrolytic solution in a state where the electrolytic solution is retained above a temperature at which the water-soluble polymer compound is aggregated, and between the first electrolytic solution tank and a supply port. And a second electrolyte tank for storing the electrolyte supplied from the first electrolyte tank,
12. The second electrolytic solution tank is provided with precooling means for cooling the electrolytic solution to a temperature lower than the temperature of the electrolytic solution supplied from the first electrolytic solution tank. The electrolytic composite polishing apparatus according to any one of claims 15 to 15.   The electrolytic composite polishing apparatus according to claim 11, further comprising a temperature control unit that cools the substrate surface.

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