JP2008174823A - Combined electropolishing method and combined electropolishing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To expose a barrier film being a lower layer of electrically conductive films by removing the electrically conductive films in an electrically insulated state without leaving the same. <P>SOLUTION: Voltage is applied to a space between a first electrode connected to one electrode of a power source and a second electrode connected to the other electrode of the power source and supplying electric power to the electrically conductive films being the object for polishing, an electrolytic solution is filled into a space between the first electrode and the electrically conductive films being the object for polishing, and while pressing the electrically conductive films against the polishing face of a polishing pad, the electrically conductive films are rubbed therewith to be polished, in this case, the electrically conductive films (copper film 307(and seed film 306)) are polished in such a manner that the barrier film 305 being the lower layer of the electrically conductive films is exposed in order from the central part of the substrate W to the outer circumferential part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a composite electropolishing method and a composite electropolishing apparatus, and in particular, composite electropolishing used for processing a conductive material on a substrate surface such as a semiconductor wafer or removing impurities adhering to the substrate surface. The present invention relates to a method and a composite electrolytic polishing apparatus.

As a wiring formation process of a semiconductor device, a so-called damascene process in which a wiring metal is buried in a wiring recess such as a trench or a via hole provided in an insulating film is being used. In this damascene process, a recess for wiring is formed in an insulating film (interlayer insulating film) made of SiO ₂ , SiOF, SiOC, or a so-called low-k material on the substrate, and then the entire surface of the insulating film including the recess for wiring is formed. Forming a barrier film made of titanium, tantalum, tungsten, ruthenium and / or alloys thereof, and forming a wiring metal film made of aluminum, copper, silver, gold, tungsten or alloys thereof on the surface of the barrier film In general, a wiring metal is embedded in the wiring recess, and then an extra wiring metal film and a barrier film formed other than the wiring recess are removed. In current high-speed devices, copper or an alloy thereof is generally used as a wiring metal, and so-called low-k materials are used as an insulating film.

  In the damascene process, the formation of the wiring recess is often performed by dry etching or the like, and the barrier film is formed by a dry process such as PVD, CVD, or ALD. Examples of the method for forming the wiring metal film include a wet process such as electrolytic plating or electroless plating, and a dry process such as PVD, CVD, or ALD, but formation by electrolytic plating is widely performed. When forming a wiring metal film by electrolytic plating when the conductivity of the barrier film is low, a seed film for power feeding is formed in advance on the surface of the barrier film in succession to the formation of the barrier film. Is widely practiced. The excess wiring metal film and the barrier film are generally removed by a so-called flattening method such as chemical mechanical polishing (CMP), electrolytic polishing, and composite electrolytic polishing. For composite electropolishing, polishing proceeds by the mechanisms of (1) electrolytic oxidation of wiring metal, (2) complexation of electrolytically oxidized wiring metal by the electrolyte component, and (3) mechanical removal of complexed wiring metal. It is considered to be.

FIG. 1 shows an example of forming a copper wiring in a semiconductor device in the order of steps. As shown in FIG. 1A, an insulating film 302 made of, for example, SiO ₂ or a low-k material is deposited on a conductive layer 301a on a semiconductor substrate 301 on which a semiconductor element is formed. Inside, a via hole 303 and a trench 304 are formed by, for example, lithography / etching technique, a barrier film 305 made of Ta or TaN or the like is formed thereon, and a seed film 306 as a power supply film for electrolytic plating is formed thereon by sputtering or the like. To do.

  Then, as shown in FIG. 1B, the surface of the semiconductor substrate W is plated with copper so that the via hole 303 and the trench 304 of the semiconductor substrate W are filled with copper, and the wiring metal film is formed on the insulating film 302. A copper film 307 is deposited. Thereafter, the copper film 307, the seed film 306, and the barrier film 305 on the insulating film 302 are removed by chemical mechanical polishing (CMP) or the like to insulate the surface of the copper film 307 filled in the via hole 303 and the trench 304. The surface of the film 302 is substantially flush with the surface. As a result, as shown in FIG. 1C, a wiring 308 composed of the seed film 306 and the copper film 307 is formed inside the insulating film 302.

  In the semiconductor device wiring formation process, along with the introduction of the low-k material accompanying the reduction of the dielectric constant of the interlayer insulating film, the reduction of damage to the low-k material such as destruction or peeling of the low-k material during polishing becomes an issue. One solution is to lower the pressure of the polishing process. Conventionally, in polishing of semiconductor wafers represented by CMP, the uniformity of the polishing rate in the wafer surface is mainly adjusted so that the polishing pressure is uniform in the wafer surface, or the wafer and polishing pad are polished during polishing. It has been ensured by making the relative speed uniform.

  FIG. 2 shows the polishing pressure dependence of the polishing rate in general CMP. As shown in FIG. 2, in the low polishing pressure region, the polishing rate increases rapidly as the polishing pressure increases. However, the polishing rate has an inflection point at a certain polishing pressure, and when the polishing pressure exceeds the inflection point, the increase rate of the polishing rate is generally small. Under conventional general polishing conditions (for example, 2 to 3 psi), the polishing pressure is slightly higher than the inflection point in FIG. 2, thereby achieving high polishing speed and uniform polishing pressure within the wafer surface. Polishing has been performed in a high state (the increase rate of the polishing rate with respect to the polishing pressure is small).

  However, in the low polishing pressure region (1.0 psi (70 hPa) or less), the rate of increase of the polishing rate with respect to the polishing pressure is large, so (1) the decrease in polishing rate is large, and (2) polishing with a slight change in polishing pressure. The big change in speed is a problem. Therefore, overcoming these problems leads to realization of polishing in a low pressure region. One solution to this is composite electropolishing that combines electrolytic action. The polishing rate in this composite electrolytic polishing is characterized by increasing depending on the applied voltage under a constant polishing pressure condition, and a high polishing rate at a low polishing pressure is possible.

In addition, in order to ensure the uniformity of the polishing rate within the wafer surface, it has been proposed to have a distribution in the applied voltage within the wafer surface during polishing (see Patent Documents 1 to 3).
JP 2003-193300 A Japanese Patent Laid-Open No. 2003-278000 US Pat. No. 6,848,970

  When the conductive film on the object to be polished by composite electrolytic polishing, for example, the wiring metal film made of copper on the substrate is polished to expose the barrier film, the conductive film remains electrically insulated on the barrier film. Among the mechanisms in the above-described composite electropolishing, (1) electrolytic oxidation of the wiring metal (conductive film) becomes impossible. For this reason, the electropolishing for the conductive film remaining in an electrically insulated state does not proceed. In this state, if the barrier film is further polished as the next step, the barrier film is non-uniformly polished by the remaining conductive film. As a result, the barrier film to be originally removed remains or the conductive film (wiring metal) Dishing and erosion increase due to overpolishing. Therefore, when removing the conductive film formed on the surface of the barrier film by composite electrolytic polishing to expose the barrier film, the conductive film is not left on the barrier film while being electrically insulated during polishing. Is required.

  The present invention has been made in view of the above circumstances, and removes the conductive film in an electrically insulated state without leaving it, so that the barrier film under the conductive film can be exposed. An object is to provide a polishing method and an electrolytic polishing apparatus.

  According to the first aspect of the present invention, there is a voltage between the first electrode connected to one electrode of the power source and the second electrode connected to the other electrode of the power source and supplying power to the conductive film of the object to be polished. Is applied to fill the electrolyte between the first electrode and the conductive film of the object to be polished, and the conductive film is rubbed against the polishing surface of the polishing pad while being rubbed for polishing. The composite electropolishing method is characterized in that the conductive film is polished so that the film is exposed in order from the center to the outer periphery of the object to be polished.

  In this way, the conductive film is electrically insulated during polishing by polishing the conductive film so that the barrier film under the conductive film is exposed in the order from the center to the outer periphery of the object to be polished. It is possible to prevent the electrically conductive film remaining on the barrier film from remaining on the barrier film without being polished.

  According to a second aspect of the present invention, the conductive film is polished so that the average film thickness of the remaining conductive film is 300 nm or less and the film thickness distribution of the remaining conductive film in the object to be polished is 150 nm or less. The composite electropolishing method according to claim 1.

  After the conductive film is polished almost flatly until the average film thickness of the remaining conductive film reaches 300 nm or less, for example, the remaining conductive film is polished at a polishing pressure that is greater in the central portion of the object to be polished than in the outer peripheral portion. Thus, the conductive film can be positively removed from the center of the object to be polished. The film thickness of the conductive film remaining on the outer periphery when the conductive film at the center of the object to be polished is removed is, for example, 100 nm or less, preferably 50 nm or less, and more preferably 20 nm or less. preferable. As a result, when a wiring metal film is used as the conductive film, the time during which the wiring metal film is exposed to the electrolytic solution is shortened, and the conductive film embedded in the trench or the like (wiring metal film) is excessively polished. This can be prevented.

  In the invention according to claim 3, the average film thickness of the remaining conductive film is 300 nm or less, and the film thickness of the remaining conductive film in the polishing object increases from the center to the outer periphery of the polishing object. The composite electrolytic polishing method according to claim 1, wherein the conductive film is polished as described above.

  In this way, the conductive film is polished so that the film thickness of the remaining conductive film in the polishing object increases from the center to the outer periphery of the polishing object, and then the remaining conductive film is made uniform. Polishing may be performed at a speed. The film thickness difference of the remaining conductive film at the end of polishing is, for example, 100 nm, preferably 50 nm or less, and more preferably 20 nm or less.

The invention according to claim 4 is characterized in that the polishing is performed under the condition that the polishing rate decreases from the central part to the outer peripheral part of the object to be polished. Is the method.
As described above, the barrier film may be exposed from the central part of the polishing object toward the outer peripheral part by performing polishing under the condition that the polishing rate decreases from the central part to the outer peripheral part of the polishing object. The polishing rate difference at the time of polishing is, for example, 100 nm / min, and preferably 50 nm / min or less.

  The invention according to claim 5 is characterized in that an electrolytic etching rate for the conductive film when the barrier film is exposed in order from the center to the outer periphery of the object to be polished is 50 nm / min or less. 5. The composite electropolishing method according to any one of 1 to 4.

  The electrolytic etching rate is a rate of etching performed by applying a potential to the conductive film in the electrolytic solution without mechanical polishing. It is considered that the metal film dishing of the wiring portion required in the future is 20 nm or less, and in normal CMP, the time from the start of exposure of the barrier film to the completion of the exposure is about 20 seconds. If the polishing rate is less than min, dishing of 20 nm or less can be achieved. In this way, by performing polishing so that the electrolytic etching rate for the conductive film is 50 nm / min or less, for example, when a wiring metal film is used as the conductive film, the conductive film (wiring metal film) embedded in the trench or the like Can be prevented from being excessively polished by being exposed to the electrolytic solution.

The invention according to claim 6 is characterized in that the polishing rate when the average film thickness of the remaining conductive film is 200 nm or less is 1/2 or less of the polishing rate when the average film thickness is 200 nm or more. The polishing method according to any one of 1 to 5.
Also by this, for example, when a wiring metal film is used as the conductive film, it is possible to prevent the conductive film embedded in the trench or the like (wiring metal film) from being excessively polished.

The invention according to claim 7 is the composite electropolishing method according to any one of claims 1 to 6, wherein two or more kinds of electrolytic solutions are used for polishing the conductive film.
In the polishing of the conductive film, when a plurality of predetermined residual films (for example, a residual film of the conductive film of 300 nm or the barrier film is exposed), the electrolytic solution component is switched to thereby expose the barrier film. It is possible to suppress electrolytic etching when started, or to increase the removal efficiency of the conductive film after the barrier film starts to be exposed.

According to an eighth aspect of the present invention, the conductive film is made of copper or a copper alloy, and the pH of the electrolytic solution is in a pH range where a passive oxide film is formed on copper as shown by a potential-pH diagram of copper. A composite electropolishing method according to claim 1, wherein:
Thereby, it is possible to prevent the conductive film from being excessively etched by forming a non-conductive oxide film on the surface of the conductive film and covering the surface of the conductive film with the non-conductive oxide film.

  Examples of the composition of the electrolyte include 2 to 80% by weight of one or more organic acids, 2 to 20% by weight of one or more strong acids having a sulfonic acid group, and 0.01 to 1% by weight of a corrosion inhibitor. , 0.01 to 1% by weight of a water-soluble polymer compound, 0.01 to 2% by weight of abrasive grains, and 0.01 to 1% by weight of a surfactant, pH = 3 to 6, Preferably, the pH is adjusted to 3 to 4.5.

  Organic acids include acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, citric acid, aconitic acid, glyoxylic acid, glycolic acid, lactic acid, gluconic acid, malic acid And tartaric acid. Examples of the strong acid having a sulfonic acid group include benzenesulfonic acid, methanesulfonic acid, taurine, cysteic acid, alkylbenzenesulfonic acid having 1 to 6 carbon atoms in total, trifluoromethanesulfonic acid, and fluorosulfonic acid.

  Examples of the corrosion inhibitor include benzotriazole and its derivatives. Examples of the water-soluble polymer compound include polyethylene glycol, polyisopropylacrylamide, polydimethylacrylamide, polymethacrylamide, polymethoxyethylene, polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, Polyvinyl pyrrolidone is mentioned. Examples of the abrasive grains include colloidal silica and fumed silica having a primary particle size of 10 nm or more.

  The electrolytic solution may be one obtained by adding an electrolyte to a normal CMP slurry. This utilizes the chemical action of the normal CMP slurry on the conductive film. By adding an electrolyte to the normal CMP slurry, for example, the conductivity of the electrolytic solution is increased or the chemical action on the CMP slurry is increased. Can be added. Here, examples of the electrolyte to be added include organic acids such as succinic acid. For example, succinic acid is added to the CMP slurry. As the pH adjuster, for example, KOH is used, and thereby the pH of the electrolytic solution is set to 5.5. When the applied voltage is changed using the electrolytic solution thus adjusted, the passive state as shown in FIG. 15A is obtained in the region of 0.8 to 1.2 (Vvs. Ag / AgCl) in terms of electrode potential. A formation region of a passivation film (passive oxide film) can be seen.

  Organic acids include succinic acid, maleic acid, citric acid, glycolic acid, acetic acid, propionic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, fumaric acid, aconitic acid, glyoxylic acid, lactic acid, gluconic acid , Malic acid and tartaric acid.

  While using these solutions, the polishing rate is reduced (for example, the applied voltage is reduced) to form a passivated film on the surface of the conductive film, which causes the conductive film to be excessively electroetched. Can be prevented.

According to the ninth aspect of the present invention, the voltage applied between the first electrode and the second electrode when the average film thickness of the remaining conductive film is 200 nm or less is polishing when the average film thickness is 200 nm or more. The composite electropolishing method according to claim 1, wherein the voltage is smaller than a voltage applied between the first electrode and the second electrode.
Also by this, it is possible to prevent the conductive film from being excessively etched by forming a non-conductive film on the surface of the conductive film by polishing at an average film thickness of 200 nm or more.

According to a tenth aspect of the present invention, the voltage applied between the first electrode and the second electrode between the start of exposure and the completion of exposure of the barrier film is an electrode potential that corrodes the conductive film. The composite electropolishing method according to claim 1, wherein the composite electropolishing method is at a potential or lower.
Thus, corrosion of the conductive film can be suppressed, and the conductive film embedded in the trench or the like (wiring metal film) can be prevented from being excessively polished.

  According to the eleventh aspect of the present invention, the waveform of the voltage applied between the first electrode and the second electrode between the start of exposure and the completion of exposure of the barrier film is a rectangular wave, a sine wave, a lamp The composite electropolishing method according to claim 1, wherein the method is a wave.

  For example, by using a waveform that once decreases the voltage, such as a rectangular wave or a ramp wave, it prevents rapid dissolution of the conductive film and suppresses surface roughness and excessive polishing of the conductive film (wiring metal film). Can do. At this time, it is desirable to set the frequency so that it does not synchronize with the period of the through hole of the polishing pad passing over a specific location of the object to be polished. Variation in film thickness distribution becomes large).

The invention according to claim 12 is the composite electropolishing method according to any one of claims 1 to 11, wherein a change in the residual film thickness of the conductive film is detected by a change in eddy current.
The invention according to claim 13 is the composite electrolytic polishing method according to claim 12, wherein the polishing end point of the conductive film is detected by the change in the eddy current.
Changes in the thickness of the conductive film to be polished and the state of exposure of the barrier film can be monitored by sensing changes in eddy current. Thereby, it is possible to prevent the conductive film from being excessively polished or the conductive film (wiring metal film) embedded in the trench or the like from being excessively polished after the barrier film starts to be exposed.

The invention according to claim 14 is the composite electropolishing method according to any one of claims 1 to 11, wherein the polishing end point of the conductive film is detected by a change in electrode potential of the conductive film.
Since the electrode potential of the conductive film to be polished and the barrier film are different, the electrode potential changes when the conductive film is removed and the barrier film is exposed. By detecting the polishing end point based on this change, it is possible to prevent the conductive film (wiring metal film) embedded in the trench or the like from being excessively polished.

  The invention according to claim 15 controls at least one of a flow rate distribution and a temperature distribution of the electrolytic solution filled between the first electrode and the conductive film of the object to be polished in the surface of the object to be polished. The composite electrolytic polishing method according to claim 1, wherein the method is a composite electrolytic polishing method according to claim 1.

  In composite electropolishing having a high polishing rate and good in-plane uniformity in a low polishing pressure region, an electrochemical reaction is caused by applying a voltage to the conductive film surface of an object to be polished such as a wafer. Parameters affecting the electrochemical reaction include an in-plane distribution of the electrolytic solution in the polishing object and a temperature distribution of the electrolytic solution. In particular, a polishing pad used for composite electrolytic polishing has a through-hole penetrating between a conductive film to be polished and an electrode (processed electrode) unlike a polishing pad used for normal CMP. The uniformity of the in-plane distribution is particularly important. That is, as shown in FIG. 10, in composite electrolytic polishing, there is a relationship between the electrolytic solution flow rate and the polishing rate that the polishing rate increases as the electrolytic solution flow rate increases. Also, as shown in FIG. 11, there is a relationship between the electrolyte temperature and the polishing rate that increases as the electrolyte temperature increases, and this relationship becomes more prominent as the polishing pressure decreases. Therefore, by controlling at least one of the flow rate distribution and the temperature distribution of the electrolyte filled between the first electrode and the conductive film of the object to be polished in the surface of the object to be polished, the conductivity of the object to be polished is controlled. The distribution of the polishing amount in the surface to be polished of the film can be controlled.

  In the invention described in claim 16, the flow rate distribution of the electrolytic solution in the surface of the object to be polished is controlled based on the difference between the film thickness distribution during polishing of the conductive film and the desired film thickness distribution. The composite electrolytic polishing method according to claim 15, wherein the flow rate of the electrolytic solution supplied from the liquid supply path is independently controlled.

The invention according to claim 17 controls the temperature distribution in the surface of the polishing object of the electrolytic solution based on the difference between the film thickness distribution during polishing of the conductive film and the desired film thickness distribution. The composite electrolytic polishing method according to claim 16, wherein the method is performed by adjusting the temperature of the electrolytic solution supplied by being controlled independently from the liquid supply path.
The temperature range of the electrolytic solution is, for example, 10 to 50 ° C.

The invention according to claim 18 is the composite electropolishing method according to any one of claims 15 to 17, wherein a relative motion speed between the polishing pad and the object to be polished is controlled.
The rotational speed of the polishing pad is controlled in the range of 20 to 40 rpm, for example, and the rotational speed of the polishing object is controlled in the range of 50 to 100 rpm, for example. The polishing object may be rotated in the direction opposite to the polishing pad, if necessary, and the polishing object may be swung in the rotation direction of the polishing pad, if necessary.

  The invention according to claim 19 has a first electrode connected to one pole of a power supply, holds a polishing table for holding a polishing pad, and a polishing object having a conductive film, and the polishing object A top ring having a plurality of pressing regions that individually press the polishing pad against the polishing surface of the polishing pad, and at least one of an outer periphery or an inner periphery of the first electrode and insulated from the first electrode. At least one second electrode that is connected to the other electrode and supplies power to the conductive film of the object to be polished; and an electrolyte supply unit that supplies at least one electrolyte to the polishing surface of the polishing pad; , A moving mechanism for moving the object to be polished and the polishing surface relative to each other, a detection unit for detecting a signal corresponding to a residual film thickness of the conductive film, and the power source based on the signal obtained from the detection unit. Applied voltage of the top ring Force, a composite electrolytic polishing apparatus characterized by a control unit for controlling at least one of the electrolytic solution supply flow rate and the relative movement velocity of the electrolytic solution supply unit.

  The polishing pressure distribution in the surface of the object to be polished is changed from, for example, a uniform state to a plurality of (three or more areas) concentric circles, and the polishing pressure at the inner periphery of the object to be polished is made higher than the remaining outer periphery ( For example, when the polishing pressure difference is 0.01 to 0.5 psi between the inner peripheral portion and the outermost peripheral portion, the polishing rate of the conductive film on the inner peripheral portion of the object to be polished can be made larger than that of the outer peripheral portion.

The invention according to claim 20 is the composite electropolishing apparatus according to claim 19, wherein the first electrode comprises a plurality of divided electrodes and can be independently controlled by the power source.
The voltage distribution in the surface of the polishing object is changed from, for example, a uniform state to a plurality (three or more areas), and the voltage of the inner periphery of the object to be polished is made higher than the remaining outer periphery (for example, the inner periphery) And a potential difference of 0.01 to 0.5 V at the outermost peripheral portion), the polishing rate of the conductive film at the inner peripheral portion of the object to be polished can be made larger than that of the outer peripheral portion.

The invention according to claim 21 is the composite electrolytic polishing apparatus according to claim 19 or 20, wherein the second electrode is made of a resin material having conductivity.
The invention according to claim 22 is characterized in that the electrolyte supply section has a plurality of electrolyte supply paths, and the supply flow rate from the electrolyte supply paths can be independently controlled by the control section. Item 22. The composite electrolytic polishing apparatus according to any one of Items 19 to 21.
In composite electropolishing, since the flow rate distribution of the electrolytic solution affects the polishing rate, the distribution of the polishing rate within the surface of the object to be polished can be controlled by adjusting the flow rate distribution of the electrolytic solution.

23. The invention according to claim 23, wherein the electrolyte supply unit further includes a temperature adjustment unit that independently adjusts the temperature of the electrolyte flowing along the plurality of electrolyte supply paths. It is a composite electropolishing apparatus of description.
In composite electropolishing, the temperature distribution of the electrolytic solution affects the polishing rate. Therefore, the distribution of the polishing rate within the surface of the object to be polished can be controlled by adjusting the temperature distribution of the electrolytic solution.

The invention according to claim 24 is the composite electrolytic polishing apparatus according to any one of claims 19 to 23, wherein the detection section is an eddy current sensor.
The film thickness change of the conductive film of the object to be polished and the state of the barrier film exposure can be monitored by sensing the change in eddy current, and this change can be monitored by polishing pressure distribution, applied voltage distribution, electrolyte flow rate distribution, and polishing target. By feeding back the relative speed condition between the object and the polishing pad, the residual conductive film thickness is controlled, and the conductive film (wiring metal film) embedded in the trench after the exposure of the barrier film is excessively polished. Can be prevented.

25. The composite electropolishing apparatus according to claim 19, wherein the detection unit is a reference electrode and detects a change in electrode potential of the conductive film. It is.
The electrode potential of the conductive film or the barrier film can be measured using a reference electrode. By detecting the polishing end point based on the change in the electrode potential, the conductive film embedded in the trench (wiring metal) It is possible to prevent the film) from being excessively polished.

The invention according to claim 26 is characterized in that the control unit controls the polishing of the conductive film so that the barrier film under the conductive film is exposed in order from the central part to the outer peripheral part of the object to be polished. A composite electrolytic polishing apparatus according to any one of claims 19 to 25.
This makes it possible to expose the barrier film under the conductive film without leaving the conductive film on the barrier film in an electrically insulated state.

  According to a twenty-seventh aspect of the present invention, there is provided a voltage between the first electrode connected to one electrode of the power source and the second electrode connected to the other electrode of the power source and supplying power to the conductive film of the object to be polished. Is applied to fill the electrolytic solution between the first electrode and the conductive film of the object to be polished, and the conductive film is rubbed against the polishing surface of the polishing pad while being rubbed to polish the barrier film below the conductive film. In the method for exposing the film, an electrolyte is used that forms a passivated film on the surface of the conductive film so that the polishing rate of the conductive film is 50 nm / min immediately before the exposure of the barrier film. This is a composite electrolytic polishing method.

  The invention described in claim 28 is a range corresponding to an electrode potential at which a passivation film is formed on the surface of the conductive film, with the supply of the electrolyte solution, and the voltage between the first electrode and the second electrode. 28. The composite electropolishing method according to claim 27.

  According to the present invention, it is possible to expose the barrier film under the conductive film without leaving the conductive film in an electrically insulated state. Therefore, when the barrier film is subsequently removed, the barrier film is exposed. And the occurrence of dishing and erosion due to overpolishing of the conductive film (wiring metal film) can be reduced as much as possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following example, an example is shown in which the barrier film is exposed by removing the copper film (and the seed film) forming the wiring formed on the surface of the barrier film of the substrate as the object to be polished.

  FIG. 3 is a plan view showing an arrangement configuration of the substrate processing apparatus provided with the composite electrolytic polishing apparatus according to the present invention. For example, as shown in FIG. 1B, this substrate processing apparatus fills the via hole 303 and the trench 304 with copper by performing copper plating on the surface, and as a wiring metal film on the insulating film 302. A substrate (object to be polished) W on which a copper film 307 is deposited is prepared, and the surface of this substrate is polished to the position indicated by the line AA in FIG. The copper film 307 (and the seed film 306) as a film is removed, and thereby the barrier film 305 is exposed. Then, by further removing the barrier film 305 on the insulating film 302, a wiring 308 composed of a seed film 306 and a copper film 307 is formed inside the insulating film 302 as shown in FIG.

  This substrate processing apparatus includes a load / unload stage that accommodates a substrate cassette 204 that stocks a large number of substrates W (see FIG. 1B) having a copper film 307 as a wiring metal film (conductive film). . 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.

  Two drying units 212 are arranged on the side opposite to the substrate cassette 204 with the traveling mechanism 200 of the transfer robot 202 as the axis of symmetry. 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 arranged at a position where the hand of the transfer robot 208 can reach, and two composite electropolishing apparatuses 250 according to the embodiment of the present invention are arranged at a position where the substrate can be delivered to the rotary transporter 210. Yes. In this example, two composite electropolishing apparatuses 250 are provided, one of which is used individually for the first polishing of the copper film 307 (and the seed film 306) and the other is used for the second polishing. Yes.

  The substrate processing apparatus includes an ITM (In-line Thickness Monitor) 224 as a measurement unit that measures a surface state such as a film thickness on a substrate surface that has been subjected to cleaning and drying processing before polishing or after polishing. That is, as shown in FIG. 3, on the extension line of the traveling mechanism 200, before the transfer robot 202 stores the polished substrate in the substrate cassette 204, or the transfer robot 202 removes the unpolished substrate from the substrate cassette 204. After taking out (In-line), an ITM (measuring unit) 224 that measures the polishing state of a copper film, a barrier layer, and the like on a substrate surface of a semiconductor wafer or the like by an optical signal incident on and reflected by the substrate surface by an optical means. Is arranged.

  Each composite electrolytic polishing apparatus 250 includes a polishing table 100, a top ring 1, an electrolytic solution supply nozzle 102 that supplies an electrolytic solution to a polishing pad 101 (see FIGS. 4 and 8, etc.) of the polishing table 100, and a polishing pad of the polishing table 100. A dresser 218 for performing dressing 101 and a water tank 222 for cleaning the dresser 218 are provided.

  FIG. 4 shows a main part of the composite electropolishing apparatus 250. As shown in FIG. 4, the top ring 1 is connected to a top ring drive shaft 11 via a universal joint 10, and the top ring drive shaft 11 is a top ring air cylinder fixed to a top ring head 110. 111. The top ring drive shaft 11 is moved up and down by the top ring air cylinder 111 to raise and lower the entire top ring 1 and press the retainer ring 3 fixed to the lower end of the top ring body 2 against the polishing table 100. The top ring air cylinder 111 is connected to the compressed air source 120 via the regulator RE1, and the regulator RE1 adjusts the fluid pressure such as the air pressure of the pressurized air supplied to the top ring air cylinder 111. Can do. Thereby, the pressing force with which the retainer ring 3 presses the polishing pad 101 can be adjusted.

  The top ring 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 top ring motor 114 as a rotation drive unit is fixed to the top ring head 110, and the timing pulley 113 is connected to a timing pulley 116 provided on the top ring motor 114 via a timing belt 115. Yes. Accordingly, when the top ring motor 114 is rotationally driven, the rotary cylinder 112 and the top ring drive shaft 11 rotate together via the timing pulley 116, the timing belt 115, and the timing pulley 113, and the top ring 1 rotates. The top ring head 110 is supported by a top ring head shaft 117 fixedly supported on a frame (not shown).

  Next, the top ring 1 will be described in more detail with reference to FIGS. 5 and 6. 5 is a longitudinal sectional view showing the top ring 1, and FIG. 6 is a bottom view of the top ring 1 shown in FIG. As shown in FIG. 5, the top ring 1 includes a cylindrical container-like top ring main body 2 having an accommodating space inside, and a retainer ring 3 fixed to the lower end of the top ring main body 2. The top ring body 2 is formed of a material having high strength and rigidity, such as metal or ceramics. The retainer ring 3 is made of, for example, a highly rigid resin material or ceramics.

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

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

  The spherical bearing mechanism includes a spherical recess 11a formed at the center of the lower surface of the top ring drive shaft 11, a spherical recess 2d formed at the center of the upper surface of the housing portion 2a, and the recesses 11a and 2d. And a bearing ball 12 made of a high hardness material such as ceramics. The rotation transmission mechanism includes a drive pin (not shown) fixed to the top ring drive shaft 11 and a driven pin (not shown) fixed to the housing portion 2a. Even if the top ring main body 2 is tilted, the driven pin and the driving pin can be moved relative to each other in the vertical direction. The rotational torque is reliably transmitted to the top ring body 2.

  In the space defined inside the top ring body 2 and the retainer ring 3 fixed integrally to the top ring body 2, there are elastic pads 4 that abut against a substrate W such as a semiconductor wafer held by the top ring 1. An annular holder ring 5 and a generally 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 top ring body 2. One end of the pressure sheet 7 is sandwiched between the housing part 2a of the top ring body 2 and the pressure sheet support part 2b, and the other end is sandwiched between the upper end part 5a of the holder ring 5 and the stopper part 5b. Has been. A pressure chamber 21 is formed inside the top ring body 2 by the top ring body 2, the chucking plate 6, the holder ring 5, and the pressure sheet 7. As shown in FIG. 5, a fluid path 31 made of a tube, a connector, or the like is communicated with the pressure chamber 21, and the pressure chamber 21 is connected to a compressed air source 120 via a regulator RE <b> 2 installed in the fluid path 31. It is connected to the. 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.

  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 top ring body 2, the elasticity of the pressure sheet 7 as an elastic body. Due to the deformation, 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 top ring body 2 and the pressure sheet support portion 2b. It is fixed with.

  Incidentally, as described in Japanese Patent Application No. 8-50956 (Japanese Patent Application Laid-Open No. 9-168964) and Japanese Patent Application No. 11-294503, the retainer ring 3 can be moved up and down with respect to the top ring body 2. In addition, the retainer ring 3 can be configured to be able to be pressed independently of the top ring body 2. In such a case, the above-described method for fixing the pressure sheet 7 is not necessarily used.

  In the space formed between the elastic pad 4 and the chucking plate 6, there are a center bag 8 (center contact member) as a contact member that contacts the elastic pad 4 and a ring tube 9 (outer contact). Member). In this example, as shown in FIGS. 5 and 6, 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.

  A space formed between the chucking plate 6 and the elastic pad 4 is partitioned into a plurality of spaces by the center bag 8 and the ring tube 9, and thus, a pressure is applied between the center bag 8 and the ring tube 9. A chamber 22 and a pressure chamber 23 are formed outside the ring tube 9, respectively.

  The center bag 8 includes an elastic film 81 that contacts the upper surface of the elastic pad 4 and a center bag holder 82 (holding portion) that holds the elastic film 81 in a detachable manner. A screw hole 82a is formed in the center bag holder 82, and the center bag 8 is detachably attached to the center portion of the lower surface of the chucking plate 6 by screwing a screw 55 into the screw hole 82a. . A center pressure chamber 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 92 (holding part) that holds the elastic film 91 in a detachable manner. A screw hole 92 a is formed in the ring tube holder 92, and the ring tube 9 is detachably attached to the lower surface of the chucking plate 6 by screwing a screw 56 into the screw hole 92 a. An intermediate pressure chamber 25 is formed in the ring tube 9 by an elastic membrane 91 and a ring tube holder 92.

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

  In the pressure chamber 21 and the pressure chambers 22 to 25 above the chucking plate 6 described above, a pressurized fluid such as pressurized air or an atmospheric pressure is provided via fluid paths 31 and 33 to 36 communicated with the pressure chambers. And vacuum is supplied. As shown in FIG. 4, the pressure of the pressurized fluid supplied to each pressure chamber can be adjusted by regulators RE <b> 2 to RE <b> 6 arranged on the fluid paths 31 and 33 to 36 of the pressure chambers 21 to 25. Thereby, the pressure inside each pressure chamber 21-25 can be controlled independently, respectively, or it can be made atmospheric pressure or a vacuum.

  Thus, by making the internal pressures of the pressure chambers 21 to 25 variable independently by the regulators RE2 to RE6, the pressing force for pressing the substrate W against the polishing pad 101 via the elastic pad 4 is applied to the portion of the substrate W. It can be adjusted for each (partition area). In some cases, these pressure chambers 21 to 25 may be connected to the vacuum source 121.

  As shown in FIG. 4, the polishing table 100 of the composite electrolytic polishing apparatus 250 is made of, for example, SUS or titanium, or is formed by covering a metal surface with platinum or the like. Embedded in the polishing table 100 is a sensor coil 228 of an ITM 226 made of, for example, an eddy current sensor for measuring the film thickness of a copper film or the like on the substrate surface. The signal from the ITM 226 is input to the control unit 400, and the regulators RE3 to RE6 are controlled by the output from the control unit 400.

  On the upper surface of the polishing table 100, as shown in FIGS. 7 and 8, a disk-shaped first electrode (cathode) 254 connected to one pole of the power source 252 and the other pole of the power source 252 are connected. The connected ring-shaped second electrodes (anodes) 256 are arranged so as to be electrically insulated from each other via an insulator 258. The upper surface of the first electrode 254 is covered with the polishing pad 101 over the entire area, and the upper surface of the polishing pad 101 is a polishing surface. In addition, the polished surface and the upper surface of the second electrode 256 are substantially flush. The power source 252 is controlled by the control unit 400.

  In this example, the second electrode 256 is arranged so as to continuously extend in a ring shape along the outer periphery of the first electrode 254. However, the second electrode extends continuously in a ring shape at the outer peripheral portion. 256 may be divided into a plurality of parts and each electrode may be connected to the power source 252. Thereby, the voltage difference in the ring-shaped second electrode can be reduced. Further, the power source 252 may be connected to the second electrode 256 continuously extending in one ring shape through a plurality of conductive wires. This also makes it possible to reduce the potential difference in the ring-shaped second electrode. Alternatively, the second electrode 256 may be formed of a pad-like conductive member.

  The second electrode 256 lowers the substrate W held by the top ring 1, and when the surface (lower surface) of the substrate W is brought into contact with the polishing surface of the polishing pad 101, this upper surface contacts the peripheral surface of the substrate W. Thus, power can be supplied to a conductive film such as a copper film 307 (see FIG. 1B) formed on the surface of the substrate W. The top ring 1 is configured to press the substrate held by the top ring 1 against the polishing surface of the polishing pad 101 with a polishing pressure of 70 hPa (about 1 psi) or less, for example.

  As shown in FIGS. 7 and 8, the polishing pad 101 is composed of an IC-1000 manufactured by Nitta Haas Co., which has a large number of through holes 101 a penetrating the entire surface. As a result, an electric current flows between the surface of the substrate W connected to the second electrode 256 and the first electrode 254 via the electrolytic solution flowing into the through-hole 101a, and electropolishing is performed. If there are through holes over the entire surface, the entire polishing pad 101 may be formed with a grid-like or annular groove. Further, if the polishing pad 101 itself is liquid-permeable, such as a polishing pad having continuous pores such as PVA resin, the polishing pad 101 does not necessarily have a through hole.

  As shown in FIG. 9, the electrolyte supply nozzle 102 extends along the radial direction of the polishing pad 102, and a plurality of electrolyte supply ports 140 are provided at predetermined intervals along the length direction. . Each electrolyte solution supply port 140 is connected to an electrolyte solution supply line (electrolyte solution supply path) 142 extending from the electrolyte solution tank. Each electrolyte solution supply line 142 is connected to the electrolyte solution supply line 142. A flow rate adjusting unit 144 having a flow rate adjusting valve or the like for individually adjusting the flow rate of the electrolyte solution flowing along, and a temperature having a heat exchanger or the like for individually adjusting the temperature of the electrolyte solution flowing along the electrolyte solution supply line 142 An adjustment unit 146 is interposed, and thereby an electrolyte supply unit 148 is configured. Each flow rate adjustment valve of the flow rate adjustment unit 144 and each heat exchanger of the temperature adjustment unit 146 include, for example, an ITM 226 such as an eddy current sensor disposed under the polishing pad 101 on the polishing table 100 side shown in FIG. Is controlled by an output signal output from the control unit 400 based on a signal input from the control unit 400 to the control unit 400.

  In the composite electrolytic polishing, as shown in FIG. 10, there is a relationship between the electrolytic solution flow rate and the polishing rate that the polishing rate increases as the electrolytic solution flow rate increases. Also, as shown in FIG. 11, there is a relationship between the electrolyte temperature and the polishing rate that increases as the electrolyte temperature increases, and this relationship becomes more prominent as the polishing pressure decreases. Therefore, the electrolyte solution is polished by using the electrolyte solution supply nozzle (102) having a plurality of electrolyte solution supply lines (electrolyte solution supply channels) 142 and a plurality of electrolyte solution supply ports 140 that can individually control the flow rate and temperature. It is preferable to supply to the pad 101, whereby the distribution of the polishing rate in the conductive film can be controlled.

  Next, the operation at the time of polishing of the composite electrolytic polishing apparatus 250 configured as described above will be described. At the time of polishing, the substrate W is held on the lower surface of the top ring 1, and the cylinder 111 connected to the top ring drive shaft 11 is operated to polish the retainer ring 3 fixed to the lower end of the top ring 1 with a predetermined pressing force. Press against the polishing surface of the polishing pad 101 of the table 100. In this state, pressurized fluid having a predetermined pressure is supplied to the pressure chambers 22 and 23, the central pressure chamber 24, and the intermediate pressure chamber 25, respectively, and the substrate W is pressed against the polishing surface of the polishing pad 101 of the polishing table 100. . At this time, the substrate W comes into contact with the upper surface of the second electrode 256 at the outer periphery thereof, and power is supplied to a conductive film such as a copper film 307 (see FIG. 1B) provided on the surface of the substrate W. It becomes possible.

  Then, the electrolyte Q is supplied from the electrolyte supply nozzle 102 while applying a voltage between the first electrode 254 and the conductive film such as the copper film 307 provided on the surface of the substrate W via the power supply 252. Thus, the electrolytic solution Q is held on the polishing pad 101, and the conductive film is polished in a state where the electrolytic solution Q exists between the lower surface of the conductive film of the substrate W and the polishing surface of the polishing pad 101.

  At this time, the flow rate distribution and the temperature distribution in the conductive film, which is the surface of the object to be polished of the electrolytic solution, affect the polishing rate. Therefore, as shown in FIG. 9, each can independently control the flow rate and the temperature. It is preferable to supply the electrolytic solution to the polishing pad 101 using the electrolytic solution supply nozzle 102 having a plurality of electrolytic solution supply ports 140, whereby the distribution of the polishing route in the conductive film can be controlled.

  Here, the portions of the substrate W positioned below the pressure chambers 22 and 23 are pressed against the polishing surface by the pressure of the pressurized fluid supplied to the pressure chambers 22 and 23, respectively. The portion of the substrate W located below the central pressure chamber 24 is polished by the pressure of the pressurized fluid supplied to the central pressure chamber 24 via the elastic film 81 and the elastic pad 4 of the center bag 8. Pressed. A portion of the substrate W positioned below the intermediate pressure chamber 25 is pressed against the polishing surface by the pressure of the pressurized fluid supplied to the intermediate pressure chamber 25 via the elastic film 91 and the elastic pad 4 of the ring tube 9. Is done.

  Therefore, the polishing pressure applied to the substrate W can be adjusted for each portion along the radial direction of the substrate W by controlling the pressure of the pressurized fluid supplied to the pressure chambers 22 to 25, respectively. That is, the controller 400 independently adjusts the pressure of the pressurized fluid supplied to the pressure chambers 22 to 25 by the regulators RE3 to RE6, and presses the substrate W against the polishing pad 101 on the polishing table 100. Is adjusted for each portion of the substrate W. In this way, the substrate W is pressed against the polishing pad 101 on the upper surface of the rotating polishing table 100 in a state where the polishing pressure is adjusted to a desired value for each portion (pressing region) of the substrate W. Similarly, the pressure of the pressurized fluid supplied to the top ring air cylinder 111 can be adjusted by the regulator RE1, and the pressing force with which the retainer ring 3 presses the polishing pad 101 can be changed.

  As described above, by appropriately adjusting the pressing force with which the retainer ring 3 presses the polishing pad 101 and the pressing force with which the substrate W is pressed against the polishing pad 101 during polishing, the central portion of the substrate W (C1 in FIG. 6). ), Distribution of polishing pressure in each part from the central part to the intermediate part (C2), the outer part (C3), the peripheral part (C4), and the outer peripheral part of the retainer ring 3 outside the substrate W is desired. Value.

  In addition, in the part located under the pressure chambers 22 and 23 of the substrate W, the pressure itself of the pressurized fluid itself, such as the part where the pressing force is applied from the fluid via the elastic pad 4 and the position of the opening 41, Are applied to the substrate W. The pressing force applied to these portions may be the same pressure, and can be pressed at any pressure. Further, at the time of polishing, since the elastic pad 4 is in close contact with the back surface of the substrate W around the opening 41, the pressurized fluid inside the pressure chambers 22 and 23 hardly leaks to the outside.

  In this manner, the substrate W can be divided into four concentric circles and ring portions (C1 to C4), and each portion (pressing region) can be pressed with independent pressing force. Although the polishing rate depends on the pressing force on the polishing surface of the substrate W, since the pressing force of each part can be controlled as described above, the polishing rates of the four parts (C1 to C4) of the substrate W are independent. It becomes possible to control to. Therefore, even if the film thickness of the thin film to be polished on the surface of the substrate W has a radial distribution, it is possible to eliminate insufficient polishing or overpolishing over the entire surface of the substrate.

  That is, even if the film to be polished on the surface of the substrate W has a different film thickness depending on the position in the radial direction of the substrate W, the film thickness of the surface of the substrate W among the pressure chambers 22 to 25 described above. The pressure of the pressure chamber located above the thick part of the substrate W is made higher than the pressure of the other pressure chambers, or the pressure of the pressure chamber located above the thin part of the surface of the substrate W is changed to other pressure chambers. By making the pressure lower than the pressure in the pressure chamber, it becomes possible to make the pressing force on the polishing surface of the thick part thicker than the pressing force on the polishing surface of the thin part, and the polishing rate of that part is increased. Can be selectively enhanced. Thus, it is possible to polish the substrate W without excess or deficiency over the entire surface without depending on the film thickness distribution at the time of film formation.

  Here, drooling that occurs at the peripheral edge of the substrate W can be prevented by controlling the pressing force of the retainer ring 3. When there is a large change in the film thickness of the film to be polished at the peripheral edge of the substrate W, the peripheral edge of the substrate W is polished by intentionally increasing or decreasing the pressing force of the retainer ring 3. The rate can be controlled. When pressurized fluid is supplied to each of the pressure chambers 22 to 25, the chucking plate 6 receives an upward force. In this example, pressure fluid is supplied to the pressure chamber 21 via the fluid path 31. The chucking plate 6 is prevented from being lifted upward by the force from each pressure chamber 22-25.

  As described above, the pressing force of the retainer ring 3 to the polishing pad 101 by the top ring air cylinder 111 and the pressurized air supplied to the pressure chambers 22 to 25 are applied to the polishing pad 101 for each portion of the substrate W. The substrate W is polished by appropriately adjusting the pressing force.

  As described above, the pressure on the substrate is controlled by independently controlling the pressures of the pressure chambers 22 and 23, the pressure chamber 24 inside the center bag 8, and the pressure chamber 25 inside the ring tube 9. Can do. Furthermore, according to this example, by changing the positions and sizes of the center bag 8 and the ring tube 9, the range for controlling the pressing force can be easily changed.

  That is, the film thickness distribution of the film formed on the surface of the substrate varies depending on the film forming method and the type of film forming apparatus. According to this example, the position and size of the pressure chamber that applies the pressing force to the substrate. The center bag 8 and the center bag holder 82 or the ring tube 9 and the ring tube holder 92 can be changed. Therefore, the position and range where the pressing force should be controlled in accordance with the film thickness distribution of the film to be polished can be changed easily and at low cost simply by exchanging a part of the top ring 1. In other words, even when there is a change in the film thickness distribution of the film to be polished on the surface of the substrate to be polished, it can be handled easily and at low cost. If the shape and position of the center bag 8 or the ring tube 9 are changed, as a result, the size of the pressure chamber 22 sandwiched between the center bag 8 and the ring tube 9 and the pressure chamber 23 surrounding the ring tube 9 can be changed. Become.

Next, the operation of the substrate processing apparatus will be described.
First, a substrate cassette 204 containing a large number of substrates W having a copper film 307 formed on the surface thereof as shown in FIG. 1B is mounted on the load / unload stage. Then, one substrate is taken out from the substrate cassette 204 by the transfer robot 202 and placed on the substrate station 206. The transfer robot 208 receives the substrate from the substrate station 206, reverses the substrate as necessary, and passes it to the rotary transporter 210. Next, the rotary transporter 210 is rotated horizontally, and the substrate supported by the rotary transporter 210 is held by the top ring 1 of one composite electrolytic polishing apparatus 250.

  Then, the substrate held by the top ring 1 is moved to the polishing position above the polishing table 100. Then, the first electrode 254 is lowered while pressing the substrate against the polishing surface of the polishing pad 101 with a predetermined polishing pressure of about 70 hPa (1 psi) or less and simultaneously supplying the electrolyte Q to the polishing pad 101. A voltage is applied to the conductive film such as the copper film 307 on the surface of the substrate via the power source 252 to polish the conductive film (first polishing). Note that holding of the substrate by vacuum suction or the like may be released while the substrate is being polished by the polishing pad 101.

  By the first polishing by the composite electrolytic polishing apparatus 250, the remaining conductive film, that is, the copper film 307 (and the seed film 306) has an average film thickness of 300 nm or less and the remaining copper film 307 (and the seed film 306) substrate. The in-plane distribution of the film thickness of the copper film 307 (and the seed film 306) is detected by the ITM 226 such as an eddy current sensor so that the in-plane film thickness distribution is 150 nm or less. The copper film 307 (and the seed film 306) is polished while adjusting the polishing pressure in each portion (pressing region) C1 to C4 shown in FIG. In this way, composite electrolytic polishing that generally has little damage to the wiring or the like is adopted in the polishing process, and for example, most of the wiring metal film formed other than the wiring concave portion that accounts for the majority of the entire polishing amount is removed by polishing. By performing the composite electrolytic polishing, it is possible to greatly reduce the damage to the wiring structure due to the polishing process.

  At this time, the flow rate and temperature of the electrolyte Q supplied to the polishing pad 101 from each electrolyte supply port 140 of the electrolyte supply nozzle 102 are controlled through a plurality of electrolyte supply lines 142 as necessary. That is, based on the difference between the film thickness distribution during polishing of the conductive film (copper film 307 (and seed film 306)) and the desired film thickness distribution, the electrolyte supplied to the polishing pad 101 from the plurality of electrolyte supply ports 140 The flow rate and temperature of the polishing object are independently controlled, thereby controlling the distribution of the polishing rate within the surface of the object to be polished.

  Further, the relative motion speed between the polishing pad 101 and the substrate W may be controlled. The rotational speed of the polishing pad 101 is controlled in the range of 20 to 40 rpm, for example, and the rotational speed of the substrate W is controlled in the range of 50 to 100 rpm, for example. The substrate W may be rotated in the opposite direction to the polishing pad 101 as necessary, and the substrate W may be swung in the radial direction of the polishing pad 101 as necessary.

  The substrate that has been subjected to the first polishing by one composite electropolishing apparatus 250 is cleaned (rinsed) with pure water or the like as necessary, and then the rotary transporter 210 is cleaned. Then, it is conveyed to the other composite electropolishing apparatus 250 and held by this top ring 1. In the composite electrolytic polishing apparatus 250 that has performed the first polishing, the polishing surface of the polishing pad 101 is conditioned by the dresser 218 to prepare for the next polishing.

  Then, the substrate held by the top ring 1 is moved to a polishing position above the polishing table 100, and then lowered to press the substrate against the polishing surface of the polishing pad 101. At the same time, the electrolytic solution Q is applied to the polishing pad 101. While supplying, a voltage is applied between the first electrode 254 and the conductive film such as the copper film 307 on the surface of the substrate via the power source 252 to leave the conductive film remaining unpolished by the first polishing, That is, the copper film 307 (and the seed film 306) on the barrier film 305 is polished. As a result, the barrier film 305 is exposed.

  Polishing by the composite electropolishing apparatus 250 is performed under the condition that the polishing rate of the conductive film decreases from the central portion to the outer peripheral portion of the substrate. That is, while the ITM 226 such as an eddy current sensor detects the in-plane distribution of the film thickness of the copper film 307 (and the seed film 306), the polishing pressure in each part (pressing area) C1 to C4 shown in FIG. The central part (C1) of the substrate W, the central part (C1) and the peripheral part concentrically from the central part toward the intermediate part (C2), the outer part (C3), and the peripheral part (C4). In the range in which the polishing pressure difference of (C4) is 0.01 (about 0.7 hPa) to 0.5 (about 35 hPa), the control unit 400 controls the lowering in order, The remaining conductive film, that is, the copper film 307 (and the seed film 306) is polished while increasing the polishing rate of the conductive film.

  At this time, as described above, the flow rate and temperature of the electrolyte Q supplied to the polishing pad 101 from each electrolyte supply port 140 of the electrolyte supply nozzle 102 through the plurality of electrolyte supply lines 142 are adjusted as necessary. Control. That is, based on the difference between the film thickness distribution during polishing of the conductive film (copper film 307 (and seed film 306)) and the desired film thickness distribution, the electrolyte supplied to the polishing pad 101 from the plurality of electrolyte supply ports 140 The flow rate and temperature of the polishing object are independently controlled, thereby controlling the distribution of the polishing rate within the surface of the object to be polished.

  Further, the relative motion speed between the polishing pad 101 and the substrate W may be controlled. The rotational speed of the polishing pad 101 is controlled in the range of 20 to 40 rpm, for example, and the rotational speed of the substrate W is controlled in the range of 50 to 100 rpm, for example. The substrate W may be rotated in the opposite direction to the polishing pad 101 as necessary, and the substrate W may be swung in the radial direction of the polishing pad 101 as necessary.

  Thus, as shown in FIG. 12, the conductive film is polished so that the barrier film 305 under the conductive film (copper film 307 (and seed film 306)) is exposed from the central portion of the substrate W toward the outer peripheral portion. However, finally, the conductive film on the barrier film 305 is completely polished and removed. In this manner, the conductive film is removed so that the barrier film 305 under the conductive film (the copper film 307 (and the seed film 306)) is exposed from the center portion to the outer peripheral portion of the polishing substrate by the second polishing. By polishing, the electrically conductive film remains on the barrier film 305 while being electrically insulated during the polishing, and the electrically insulated electrically conductive film remains on the barrier film 305 without being polished. Can be prevented.

  The film thickness of the conductive film remaining on the outer periphery when the conductive film at the center of the substrate W shown in FIG. 12 is removed and the barrier film 305 is exposed, that is, the copper film 307 (and the seed film 306) is, for example, 100 nm. Or less, preferably 50 nm or less, and more preferably 20 nm or less. This shortens the exposure time to the electrolytic solution and prevents the conductive film (wiring metal film) embedded in the trench or the like from being excessively polished when the wiring metal film is used as the conductive film. be able to.

  During polishing, an electrolytic solution is used in which the electrolytic etching rate for the conductive film, that is, the copper film 307 (and the seed film 306) when the barrier film is exposed in the order from the center to the outer periphery of the object to be polished is 50 nm / min or less. It is preferable to do. The electrolytic etching rate is a rate of etching performed by applying a potential to the conductive film in the electrolytic solution without mechanical polishing. Thus, by polishing so that the electrolytic etching rate for the conductive film is 50 nm / min or less, for example, when a wiring metal film is used as the conductive film, the conductive film embedded in the trench or the like (wiring) It is possible to prevent the metal film) from being excessively polished by being exposed to the electrolytic solution.

  The polishing rate of the conductive film when the average film thickness of the remaining conductive film is 200 nm or less may be ½ or less of the polishing rate of the conductive film when the average film thickness is 200 nm or more. When a wiring metal film is used as the film, it is possible to prevent the conductive film (wiring metal film) embedded in the trench or the like from being excessively polished.

The pH of the electrolytic solution used for polishing copper is a passive oxide film (CuO, Cu ₂ O) on copper as shown in FIG. 13, which is a copper potential-pH diagram (Pourbaix-Diagram). It is preferable that it exists in the pH range which forms. The pH region in which the copper non-conductive oxide film (CuO, CU ₂ O) is formed with the aqueous electrolytic solution is a potential in which the existence region of chemical species (copper) in water is illustrated on the two-dimensional coordinates of the electrode potential and pH. -Although it is roughly defined in the pH diagram (Pourbaix-Diagram), this pH region is 4 to 12.5 in the example shown in FIG. 13, but the type of electrolyte added to the electrolyte It depends on. The potential-pH diagram is created based on thermodynamic data (equilibrium theory). As a result, as shown in FIG. 14, when the barrier film 305 is exposed, a non-conductive oxide film is formed on the surface of the conductive film buried in the trench 304 and forming the wiring 308 (see FIG. 1C). 310 is formed and the surface is covered with a non-conductive oxide film 310 to prevent the wiring 308 from being excessively etched. The pH of the electrolytic solution is preferably on the weakly acidic side such as pH = 3 to 4.5, for example, to prevent copper electrolytic etching, rather than the strong acidity in which copper is actively dissolved as Cu ²⁺ .

  Examples of the composition of the electrolytic solution include those containing a corrosion inhibitor, abrasive grains, a complexing agent, a pH adjusting agent, a surfactant and the like. For the purpose of further protecting the passive oxide film, a compound containing N, S or P that easily binds to copper, for example, N-based compounds such as benzotriazole and derivatives thereof, (benz) imidazole and derivatives thereof, fatty acid alkanolamide, etc. Anionic surfactants, polymers such as polyethyleneimine and polyacrylamide, etc. S-type, thiosalicylic acid, 6-dibutylamino-1,3,5-triazine-2,4-dithiol, etc. P-type, phosphate ester It is preferable to use a corrosion inhibitor such as an anionic surfactant.

The electrolyte of the electrolyte is preferably a substance that binds to copper, such as oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, citric acid, glycolic acid, lactic acid, gluconic acid, malic acid, ascorbic acid, pyruvic acid, Examples include glyoxylic acid, acetic acid, propionic acid, butyric acid, aconitic acid, tartaric acid, phosphoric acid, amino acids (such as glycine), ethylenediamine, and ethylenediaminetetraacetic acid.
Examples of the abrasive grains contained in the electrolytic solution include silica oxide (fumed, colloidal), aluminum oxide, zirconium oxide, cerium oxide, titanium oxide, manganese oxide and the like.

  Further, as another composition example of the electrolytic solution, 2 to 80% by weight of one or more organic acids, 2 to 20% by weight of a strong acid having one or more sulfonic acid groups, 0.01 to 1% by weight It contains a corrosion inhibitor, 0.01 to 1% by weight of a water-soluble polymer compound, 0.01 to 2% by weight of abrasive grains and 0.01 to 1% by weight of a surfactant, and pH = 3 to 3 What was adjusted to 4.5 is mentioned.

  Organic acids include acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, citric acid, aconitic acid, glyoxylic acid, glycolic acid, lactic acid, gluconic acid, malic acid And tartaric acid. Examples of the strong acid having a sulfonic acid group include benzenesulfonic acid, methanesulfonic acid, taurine, cysteic acid, alkylbenzenesulfonic acid having 1 to 6 carbon atoms in total, trifluoromethanesulfonic acid, and fluorosulfonic acid.

  Examples of the corrosion inhibitor include benzotriazole and its derivatives. Examples of the water-soluble polymer compound include polyethylene glycol, polyisopropylacrylamide, polydimethylacrylamide, polymethacrylamide, polymethoxyethylene, polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, polyacrylic acid or a salt thereof, polymethacrylic acid or a salt thereof, Polyvinyl pyrrolidone is mentioned. Furthermore, examples of the abrasive grains include colloidal silica and fumed silica having a primary particle diameter of 10 nm or more.

  The voltage applied between the first electrode 254 and the second electrode 256 when the average film thickness of the remaining conductive film is 200 nm or less, that is, between the conductive film such as the copper film 307 is the average film thickness. Is smaller than the voltage applied between the first electrode 254 and the second electrode 256, that is, between the conductive film such as the copper film 307 and the like, for example, 4 to 5 V or less. desirable.

  FIG. 15 shows the relationship between the current value and the electrode potential during polishing. In the region A where the current value shown in FIG. 15 decreases and the current hardly flows, that is, the electrode potential of 0.8 to 1.2 (Vvs. Ag / AgCl), the passivation film (passivation) is formed on the surface of the conductive film. In the region where the oxide potential is higher than the electrode potential at this time, the passivating film on the surface of the conductive film is considered to be destroyed. Therefore, when the average film thickness of the conductive film is 200 nm or more, the polishing rate is increased by applying a voltage (voltage larger than the region A) that destroys the passivation film to increase the polishing rate, and the average film of the conductive film In polishing with a thickness of 200 nm or less, a voltage corresponding to the region A is applied to form a non-conductive film on the surface of the conductive film, and the conductive film is prevented from being excessively etched by covering the surface. can do.

  Applied between the first electrode 254 and the second electrode 256 between the start of exposure of the barrier film 305 and the completion of exposure, that is, between the conductive film such as the copper film 307 via the power source 252. The voltage to be applied is preferably equal to or lower than the corrosion potential of the conductive film such as the copper film 307 as an electrode potential. Thereby, corrosion of the conductive film can be suppressed and the conductive film (wiring metal film) embedded in the trench or the like can be prevented from being excessively polished.

  In addition, the voltage is applied between the first electrode 254 and the second electrode 256, that is, the conductive film such as the copper film 307, through the power source 252 between the start of exposure of the barrier film 305 and the completion of exposure. The voltage waveform is preferably one of a rectangular wave shown in FIG. 16 (a), a sine wave shown in FIG. 16 (b), or a ramp wave shown in FIG. 16 (c).

For example, by using a waveform that once decreases the voltage, such as a rectangular wave or a ramp wave, rapid dissolution of the conductive film 307 is prevented, and surface roughness and excessive polishing of the conductive film (wiring metal film) are suppressed. be able to. At this time, it is desirable to set the frequency so as not to synchronize with the period of the through hole 101a of the polishing pad 101 passing over a specific portion of the conductive film 307. This is because when the frequency and the through-hole 101a of the polishing pad 101 passing over a specific portion of the conductive film 307 are synchronized, a processed / non-processed portion is generated, and the variation in the film thickness distribution of the conductive film is increased. Because.
Note that, at the end of polishing, in order not to impair the polishing performance, it is preferable to first stop the application of voltage, and then end the supply of the electrolytic solution.

  Then, the substrate that has been polished by the composite electrolytic polishing apparatus 250 passes through the rotary transporter 210 and the transfer robot 208, is reversed as necessary, and is transferred to the cleaning unit 214. In the composite electrolytic polishing apparatus 250 that has performed the polishing, the polishing surface of the polishing pad 101 is conditioned by the dresser 218 to prepare for the next polishing.

  Then, the cleaning unit 214 performs cleaning rinsing processing on the surface of the substrate, and the substrate after the cleaning rinsing is transferred to the substrate station 206 by the transfer robot 208 and placed. The transport robot 202 (or 206) takes out the cleaned substrate from the substrate station 206 and transports it to the drying unit 212 having, for example, a top surface cleaning sponge and a spin dry function, and the drying unit 212 cleans and dries the substrate. . Then, the substrate after cleaning and drying is returned to the original substrate cassette 204 by the transfer robot 202.

  17 and 18 show another example of the polishing table. In this example, a ring-like shape connected to one pole of the power source 252 is provided on the upper surface of the polishing table 100 (see FIG. 4). A first electrode (cathode) 254a and a ring-shaped second electrode (anode) 256a connected to the other pole of the power source 252 are disposed so as to be electrically insulated from each other via an insulator 258a. . The upper surface of the first electrode 254a is covered with a polishing pad 101 having a large number of through-holes 101a over the entire area, and the upper surface of the polishing pad 101 is a polishing surface. In addition, the polished surface and the top surfaces of the second electrode 256a and the insulator 258a are substantially flush.

  In this example, the second electrode 256a is disposed so as to continuously extend in a ring shape along the inner periphery of the first electrode 254a, and is embedded in the insulator 258a. The second electrode 256a continuously extending in a ring shape on the inner peripheral portion may be divided into a plurality of electrodes, and each electrode may be connected to the power source 252, and the second electrode 256a may be connected by a pad-like conductive member. The electrode 256a may be configured as described above.

  19 and 20 show another example of the polishing table. In this example, the upper surface of the polishing table 100 (see FIG. 4) is concentrically divided into a plurality (four). A first electrode (cathode) 260 constituted by the electrodes 260a to 260d and a ring-shaped second electrode (anode) 262 surrounding the first electrode 260 are electrically connected to each other through an insulator 264. Are electrically insulated. Each divided electrode 260 a to 260 d of the first electrode 260 is individually connected to one pole of the power source 266, and the second electrode 262 is connected to the other pole of the power source 266. The upper surface of the first electrode 260 is covered with a polishing pad 101 having a large number of through holes 101a over the entire area, and the upper surface of the polishing pad 101 is a polishing surface. Further, the polished surface and the upper surface of the second electrode 262 are substantially flush with each other. The power source 266 controls the potentials of the divided electrodes 260a to 260d with a signal from the control unit 400 (see FIG. 3).

  According to this example, the average film thickness of the remaining conductive film, that is, the copper film 307 (and the seed film 306) is 300 nm or less, and the film thickness distribution in the substrate surface of the remaining copper film 307 (and the seed film 306). The ITM 226 such as an eddy current sensor detects the in-plane distribution of the film thickness of the copper film 307 (and the seed film 306), and each of the first electrodes 260 is controlled via the control unit 400. The copper film 307 (and the seed film 306) is polished while individually adjusting the potentials of the divided electrodes 260a to 260d.

  Then, while detecting the in-plane distribution of the film thickness of the copper film 307 (and the seed film 306) with the ITM 226 such as an eddy current sensor, the potentials of the divided electrodes 260a to 260d of the first electrode 260 are set to, for example, the potential difference. In the range of 0.01 to 0.5 V, the remaining conductive film, that is, the copper film 307 (ie, the copper film 307 ( And the seed film 306) is polished.

  Thus, as shown in FIG. 12, the conductive film is polished so that the barrier film 305 under the conductive film (copper film 307 (and seed film 306)) is exposed from the center of the substrate W toward the outer periphery. However, finally, the conductive film on the barrier film 305 is completely polished and removed.

  Whether or not the conductive film (copper film 307 (and seed film 306)) on the barrier film 305 has been completely removed is determined by monitoring the eddy current change by the eddy current sensor and detecting the polishing end point. Also good. As shown in FIG. 4, the sensor coil 228 of the ITM 226 such as an eddy current sensor is disposed below the polishing pad 101 on the polishing table 100 side, for example. Further, by utilizing the difference in electrode potential between the conductive film and the barrier film, a change in electrode potential may be monitored using a reference electrode, thereby detecting the polishing end point. The reference electrode is preferably present in the vicinity of the object to be polished. For example, the reference electrode may be brought close to the object to be polished through the retainer ring of the top ring or the outer periphery of the retainer ring, or from the polishing table side through the through hole of the polishing pad.

  When the polishing table shown in FIGS. 19 and 20 is used, the top ring 1 having a plurality of individually adjustable portions (pressing regions) C1 to C4 shown in detail in FIGS. 5 and 6 is not necessarily provided. Although it is not necessary to use both, it is possible to perform finer control by using both. Furthermore, it is preferable to supply the electrolytic solution to the polishing pad 101 using the electrolytic solution supply nozzle 102 having a plurality of electrolytic solution supply ports 140 that can individually control the flow rate and the temperature. The distribution of the polishing route can be controlled.

  In the above example, the conductive film is polished so that the average film thickness of the remaining conductive film is 300 nm or less, and the film thickness distribution in the substrate surface of the remaining conductive film is 150 nm or less. The remaining conductive film is polished under the condition that the polishing rate decreases from the center to the outer periphery. Instead, in the first polishing, the average film thickness of the remaining conductive film is 300 nm or less, and the film thickness of the remaining conductive film in the substrate surface is increased from the central portion toward the outer peripheral portion of the substrate. The conductive film may be polished, and then the remaining conductive film may be polished under the condition that the polishing rate is the same over the entire surface of the substrate.

  Also by this, the conductive film is polished so that the barrier film 305 under the conductive film (copper film 307 (and seed film 306)) is exposed from the center portion of the substrate W toward the outer peripheral portion, as shown in FIG. However, finally, the conductive film on the barrier film 305 can be completely polished and removed. In this case, the difference in film thickness of the conductive film remaining at the end of the first polishing is, for example, 100 nm, preferably 50 nm or less, and more preferably 20 nm or less.

  Further, the polishing rate difference between the central part and the outer peripheral part of the polishing object is, for example, 100 nm / min, preferably 50 nm / min or less so that the polishing speed decreases from the central part to the outer peripheral part of the polishing object. The conductive film (copper film 307 (and seed film 306)) may be polished under various conditions.

In the above example, two composite electrolytic polishing apparatuses are provided, and the first polishing and the second polishing are performed separately by different electrolytic polishing apparatuses. Is used, and the first polishing and the second polishing can be performed by changing the polishing pressure and / or the voltage applied between the first electrode and the second electrode (conductive film). The first polishing and the second polishing can be continuously performed with one composite electrolytic polishing apparatus.
In the above example, a substrate such as a semiconductor wafer is used as an object to be polished. However, the object to be polished is not limited to a substrate such as a semiconductor wafer.

  FIG. 21 shows still another example of the polishing table. As shown in FIG. 21, in this example, three electrolyte flow paths (electrolyte supply paths) 412 are formed inside a rotatable polishing table 410, and each electrolyte solution is provided on the upper surface of the polishing table 410. Electrolyte reservoir chambers 414 communicating individually with the flow path 412 are formed concentrically. Further, each electrolyte flow path 412 in the polishing table 410 extends from the electrolyte tank 418 via a rotary joint 416 connected to the lower end of the shaft portion of the polishing table 410, and the electrolyte main lines 420 to 3 in the middle. Each branch electrolyte line 422 branched into two communicates with each other. Further, a liquid feed pump 424 is installed in the electrolyte main line 420, and further, a flow rate adjusting unit 428 having a flow rate adjusting valve 426 for adjusting the flow rate of the electrolyte flowing in each branch electrolyte line 422, and each branch electrolysis. A temperature adjustment unit 432 having a heat exchanger 430 for adjusting the temperature of the electrolyte flowing in the liquid line 422 is provided. As a result, an electrolyte supply unit 434 is configured.

  A disc-shaped first electrode (cathode) 438 is attached to the upper surface of the polishing table 410 via an insulating plate 436, and a rod-like shape is placed on the support base 440 disposed on the side of the polishing table 410. A second electrode 442 is attached. The insulating plate 436 and the first electrode 438 are provided with a large number of communication holes 436a and 438a communicating with each other. The first electrode 438 is connected to one pole of the power supply 446 via a slip ring 444 attached to the lower end of the shaft portion of the polishing table 410, and the second electrode 442 is connected to the other electrode of the power supply 446. Connected. The upper surface of the first electrode 438 is covered with a polishing pad 101 having a large number of through holes 101a inside the entire area, and the upper surface of the polishing pad 101 is a polishing surface. The polished surface and the upper surface of the second electrode 442 are substantially flush with each other.

  A film thickness detection sensor 448 is embedded in the polishing table 410 with its upper end surface exposed to the surface of the first electrode 438, and an output signal from the film thickness detection sensor 448 is output from the lower end of the shaft portion of the polishing table 410. The flow rate adjustment valve 426 of the flow rate adjustment unit 428 and each heat exchanger 430 of the temperature adjustment unit 432 are controlled by an output signal from the control unit 400 via the slip ring 450 provided in The

  Even in this example, similarly to the above-described example, the power supply 446 is rotated by pressing the lower surface (front surface) of the substrate W held by the top ring 1 against the surface (polishing surface) of the rotating polishing pad 101. From the electrolyte supply unit 434, a voltage is applied between the first electrode 438 and a conductive film such as a copper film 307 provided on the surface of the substrate W and in contact with the second electrode 442. By supplying the electrolytic solution to the polishing pad 101, the conductive film is polished. At this time, for example, based on the difference between the film thickness distribution and the desired film thickness distribution during polishing of the conductive film (copper film 307 (and seed film 306)), a plurality of electrolyte flow paths (electrolyte supply paths) 412 are passed through. The flow rate and temperature of the electrolytic solution supplied to the polishing pad 101 are independently controlled, whereby the distribution of the polishing rate within the conductive film surface can be controlled.

  FIG. 22 shows a main part of a composite electrolytic polishing apparatus according to another embodiment of the present invention. In this example, a polishing table 500 having a diameter slightly larger than the diameter of the substrate W held by the top ring 1 is used. The polishing table 500 differs from the polishing table 410 shown in FIG. 21 only in overall size, and has substantially the same internal structure, so that it is the same as that shown in FIG. Reference numerals are assigned and explanations thereof are omitted.

Then, the rotation center of the top ring 1 and the rotation center of the polishing table 500 are arranged at positions slightly shifted from each other, and both the top ring 1 and the polishing table 500 are rotated to rotate the substrate W held by the top ring 1. When the surface (lower surface) is rubbed while being pressed against the surface (polishing surface) of the polishing pad 101 covering the upper surface of the polishing table 500, the center of rotation of the polishing table 500 is always covered by the substrate W held by the top ring 1. (Center over).
According to this example, the entire surface of the substrate can be reliably polished and the electrolytic solution can be effectively used while reducing the size and size of the composite electropolishing apparatus.

It is a figure which shows the copper wiring formation example in a semiconductor device in order of a process. It is a graph which shows the relationship between the grinding | polishing speed and grinding | polishing pressure in general CMP. It is a top view which shows the arrangement configuration of the substrate processing apparatus provided with the composite electropolishing apparatus according to the present invention. It is a longitudinal front view which shows the principal part of the composite electropolishing apparatus of embodiment of this invention with which the substrate processing apparatus shown in FIG. 3 is equipped. It is a longitudinal cross-sectional view of the top ring of a composite electrolytic polishing apparatus. It is a bottom view of the top ring of a composite electrolytic polishing apparatus. It is a top view which shows the 2nd electrode and polishing pad of the grinding | polishing table of a composite electropolishing apparatus with a board | substrate. It is a vertical front view of FIG. It is a top view which shows the electrolyte solution supply nozzle of the grinding | polishing table of a composite electropolishing apparatus with a board | substrate and a dresser. It is a graph which shows the relationship between the grinding | polishing speed and electrolyte solution flow volume in composite electropolishing. It is a graph which shows the relationship between the grinding | polishing speed and electrolyte solution temperature in composite electropolishing. It is a figure attached | subjected to description of the exposure state of a barrier film | membrane between after a barrier film | membrane starts exposure until completion of exposure. It is an electric potential-pH figure of copper. It is sectional drawing which shows the state in which the passivation film (passivation oxide film) was formed in the surface of an electrically conductive film (wiring). It is a graph which shows the relationship between the electric current value and electrode potential in complex electropolishing. It is a figure which shows the waveform from which the voltage applied between a barrier film | membrane from an exposure start to an exposure completion differs, respectively. It is a top view which shows the 1st electrode, 2nd electrode, and polishing pad of another grinding | polishing table of a composite electropolishing apparatus with a board | substrate. It is a vertical front view of FIG. It is a top view which shows the 1st electrode, 2nd electrode, and polishing pad of another grinding | polishing table of a composite electropolishing apparatus with a board | substrate. FIG. 20 is a longitudinal front view of FIG. 19. It is a front view which shows the outline | summary of the further another polishing table of a composite electrolytic polishing apparatus. It is a front view which shows the outline | summary of the other composite electropolishing apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Top ring 2 Top ring main body 3 Retainer ring 4 Elastic pad 5 Holder ring 6 Chucking plate 7 Pressure sheet 8 Center bag 9 Ring tube 21-25 Pressure chamber 100,410,500 Polishing table 101 Polishing pad 101a Through-hole 102 Electrolysis Liquid supply nozzle 120 Compressed air source 121 Vacuum source 142 Electrolyte supply line (electrolyte supply path)
144, 428 Flow rate adjusting units 146, 432 Temperature adjusting units 148, 434 Electrolyte supply unit 204 Substrate cassette 206 Substrate station 210 Rotary transporter 212 Drying unit 214 Cleaning unit 218 Dresser 222 Water tanks 224, 226 ITM
250 Composite Electropolishing Devices 252, 252a, 266, 446 Power Sources 254, 254a, 260, 438 First Electrodes 256, 256a, 262, 442 Second Electrodes 258, 258a, 264 Insulators 260a-260d Split Electrodes 305 Barrier Film 306 Seed film (conductive film)
307 Copper film (conductive film)
308 Wiring 310 Non-conductive oxide film 400 Control unit 412 Electrolyte flow path (electrolyte supply path)
448 Film thickness detection sensor

Claims (28)

A voltage is applied between the first electrode connected to one electrode of the power source and the second electrode connected to the other electrode of the power source and supplying power to the conductive film of the object to be polished, and the first electrode When filling the electrolytic solution between the conductive film and the conductive film of the object to be polished, and rubbing while pressing the conductive film against the polishing surface of the polishing pad,
A composite electrolytic polishing method comprising polishing the conductive film so that a barrier film under the conductive film is exposed in order from the center to the outer periphery of the object to be polished.   The conductive film is polished so that an average film thickness of the remaining conductive film is 300 nm or less and a film thickness distribution of the remaining conductive film in an object to be polished is 150 nm or less. Composite electrolytic polishing method.   Polishing the conductive film so that the average film thickness of the remaining conductive film is 300 nm or less and the film thickness of the remaining conductive film in the polishing object increases from the center to the outer periphery of the polishing object. The composite electropolishing method according to claim 1 or 2, wherein:   The composite electrolytic polishing method according to claim 1, wherein the polishing is performed under a condition that the polishing rate decreases from the center to the outer periphery of the object to be polished.   5. The electrolytic etching rate for the conductive film when the barrier film is exposed in order from the center to the outer periphery of the object to be polished is 50 nm / min or less. Composite electrolytic polishing method.   6. The composite according to claim 1, wherein a polishing rate when the average film thickness of the remaining conductive film is 200 nm or less is 1/2 or less of a polishing rate when the average film thickness is 200 nm or more. Electropolishing method.   The composite electrolytic polishing method according to claim 1, wherein two or more kinds of electrolytic solutions are used for polishing the conductive film.   8. The conductive film is made of copper or a copper alloy, and the pH of the electrolytic solution is in a pH range where a passive oxide film is formed on copper as shown by a potential-pH diagram of copper. The composite electropolishing method according to any one of the above.   The voltage applied between the first electrode and the second electrode when the average film thickness of the remaining conductive film is 200 nm or less is applied to the first electrode and the second electrode by polishing when the average film thickness is 200 nm or more. The composite electropolishing method according to claim 1, wherein the voltage is smaller than a voltage applied between the two electrodes.   The voltage applied between the first electrode and the second electrode during the period from the start of exposure to the completion of exposure of the barrier film is an electrode potential equal to or lower than the corrosion potential of the conductive film. The composite electrolytic polishing method according to claim 1.   The waveform of the voltage applied between the first electrode and the second electrode between the start of exposure and the completion of exposure of the barrier film is one of a rectangular wave, a sine wave, and a ramp wave. The composite electrolytic polishing method according to claim 1, wherein:   The composite electrolytic polishing method according to claim 1, wherein a change in the residual film thickness of the conductive film is detected by a change in eddy current.   The composite electrolytic polishing method according to claim 12, wherein a polishing end point of the conductive film is detected by a change in the eddy current.   The composite electrolytic polishing method according to claim 1, wherein the polishing end point of the conductive film is detected by a change in electrode potential of the conductive film.   The control unit controls at least one of a flow rate distribution and a temperature distribution of an electrolyte filled between the first electrode and a conductive film of the polishing object within the surface of the polishing object. The composite electrolytic polishing method according to any one of 14.   Control of the flow rate distribution of the electrolytic solution in the surface of the object to be polished, based on the difference between the film thickness distribution and the desired film thickness distribution during polishing of the conductive film, the electrolytic solution supplied from a plurality of electrolytic solution supply paths The composite electrolytic polishing method according to claim 15, wherein the flow rate is controlled independently.   The temperature distribution of the electrolytic solution in the polishing object surface is controlled independently from a plurality of electrolytic solution supply paths based on the difference between the film thickness distribution and the desired film thickness distribution during polishing of the conductive film. The composite electrolytic polishing method according to claim 16, wherein the method is performed by adjusting the temperature of the supplied electrolytic solution.   The composite electrolytic polishing method according to claim 15, wherein a relative motion speed between the polishing pad and the object to be polished is controlled. A polishing table having a first electrode connected to one pole of a power supply and holding a polishing pad;
A top ring having a plurality of pressing regions for holding a polishing object having a conductive film and individually pressing the polishing object against the polishing surface of the polishing pad;
At least one of at least one of an outer periphery and an inner periphery of the first electrode is insulated from the first electrode and connected to the other electrode of the power source to supply power to the conductive film of the object to be polished. Two electrodes;
An electrolytic solution supply unit that supplies at least one type of electrolytic solution to the polishing surface of the polishing pad;
A moving mechanism for relatively moving the object to be polished and the polishing surface;
A detection unit for detecting a signal corresponding to the residual film thickness of the conductive film;
A control unit that controls at least one of the applied voltage of the power source, the pressing force of the top ring, the electrolyte solution supply flow rate of the electrolyte solution supply unit, and the relative movement speed based on a signal obtained from the detection unit; A composite electropolishing apparatus comprising:   The composite electropolishing apparatus according to claim 19, wherein the first electrode includes a plurality of divided electrodes and can be independently controlled by the power source.   21. The composite electrolytic polishing apparatus according to claim 19, wherein the second electrode is made of a resin material having conductivity.   The said electrolyte solution supply part has a some electrolyte solution supply path, The supply flow rate from this electrolyte solution supply path is independently controllable by a control part, The Claim 19 thru | or 21 characterized by the above-mentioned. Composite electropolishing equipment.   The composite electrolytic polishing apparatus according to claim 22, wherein the electrolytic solution supply unit further includes a temperature adjusting unit that independently adjusts the temperature of the electrolytic solution flowing along the plurality of electrolytic solution supply paths.   24. The composite electrolytic polishing apparatus according to claim 19, wherein the detection unit is an eddy current sensor.   The composite electropolishing apparatus according to claim 19, wherein the detection unit is a reference electrode, and detects a change in electrode potential of the conductive film.   The said control part controls the grinding | polishing of this electrically conductive film so that the barrier film of the lower layer of the said electrically conductive film may be exposed in order of the outer peripheral part from the center part of a grinding | polishing target object. The composite electropolishing apparatus according to 1. A voltage is applied between the first electrode connected to one electrode of the power source and the second electrode connected to the other electrode of the power source and supplying power to the conductive film of the object to be polished, and the first electrode And filling the electrolyte between the conductive film of the object to be polished, rubbing and polishing the conductive film while pressing it against the polishing surface of the polishing pad, and exposing the barrier film under the conductive film,
A composite electropolishing method characterized by using an electrolytic solution that forms a passivated film on the surface of the conductive film so that the polishing rate of the conductive film is 50 nm / min immediately before the exposure of the barrier film.   The voltage between the first electrode and the second electrode is set in a range corresponding to an electrode potential at which a passivation film is formed on the surface of the conductive film together with the supply of the electrolytic solution. 27. The composite electrolytic polishing method according to 27.

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