JP2008279539A - Method and device for recovering polishing fluid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently recover a polishing fluid (slurry) used for chemical machine polishing, and also to provide a method and a device for recovering the polishing fluid in a less contaminated state in each kind of contamination. <P>SOLUTION: In the recovery method for the polishing fluid in the chemical machine polishing method, a substrate is arranged between a polishing pad and a polishing head so as to supply the polishing fluid, and a surface of the substrate is polished by relative rotational movements between the polishing pad and the polishing head. The polishing fluid already used for polishing is sucked and recovered from a surface of the polishing pad by a suction nozzle. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polishing liquid recovery technique used for chemical mechanical polishing, which is a technique for planarizing a substrate in a semiconductor manufacturing process, a wafer manufacturing process, a glass substrate manufacturing process, and the like.

  In recent years, new microfabrication techniques have been developed along with higher integration and higher performance of semiconductor integrated circuits (hereinafter abbreviated as LSI). The CMP method is one of them, and is a planarization method that combines chemical reaction and mechanical polishing. In the LSI manufacturing process, in particular, in the multilayer wiring formation process, planarization of the interlayer insulating film, formation of the metal plug, embedded wiring This technique is frequently used in the formation of a film (see Patent Document 1).

  Recently, copper and copper alloys have begun to be used in place of conventional aluminum alloys as wiring materials in order to improve the performance of LSIs. However, since copper and copper alloys are difficult to be finely processed by the dry etching method used in forming aluminum alloy wiring, a copper alloy thin film is deposited and embedded on a substrate on which grooves have been formed in advance, and copper alloy thin films other than the groove portions A method (so-called damascene method) in which embedded wiring is formed by removing the film by CMP is mainly employed.

  When polishing a substrate by CMP, a polishing pad is affixed on a circular polishing platen (platen), the surface of the polishing pad is moistened with a polishing liquid (hereinafter also referred to as “slurry”), and the substrate is While pressing by applying a predetermined pressure from the back surface, the polishing surface plate (polishing pad) is rotated, and the convex portion is removed by mechanical friction between the slurry and the convex portion of the substrate surface. . At this time, by performing the pressing using a polishing head, mechanical friction resulting from the rotation of the polishing pad and the rotation of the polishing head is added to the substrate, and both surfaces thereof are flattened simultaneously. (See Patent Document 2).

  However, in the above-described conventional CMP method, the slurry after polishing is flowed from the periphery of the polishing platen to the drain outlet of the polishing apparatus, and further to the wastewater treatment facility to be collected and collected. In such a case, when a wafer trouble or the like occurs, the wafer is broken and the fragments and fine particles accumulate around the platen. Normally, if a drainage port is used, these contaminants are involved and become contained in the recovered liquid.

Further, after the substrate is polished, the substrate is washed with wafer rinsing water, dressing water, or the like, and thus such water is introduced into the wastewater treatment facility in the same process as the slurry recovery. As a result, the concentration of the recovered slurry is decreased due to the dilution with water as compared with the concentration of the slurry at the time of polishing. For this reason, when the recovered slurry and the recovered slurry are used for polishing again, it is necessary to adjust the slurry concentration, and the slurry cannot be efficiently recycled.
US Pat. No. 4,944,836 JP 2003-332281 A

  In view of the above problems, an object of the present invention is to efficiently recover a polishing liquid (slurry) used for chemical mechanical polishing and to provide a polishing liquid recovery method and a recovery apparatus in which various types of contamination are low. And

In order to achieve the above object, the present invention provides:
A substrate is disposed between a polishing pad and a polishing head, a polishing liquid is supplied, and the surface of the substrate is polished by a relative rotational movement between the polishing pad and the polishing head. A collection method,
The present invention relates to a polishing liquid recovery method, wherein the polishing liquid after polishing is sucked and recovered from the surface of the polishing pad by a suction nozzle.

The present invention also provides:
A substrate is disposed between a polishing pad and a polishing head, a polishing liquid is supplied, and the surface of the substrate is polished by a relative rotational movement between the polishing pad and the polishing head. A recovery device,
A suction nozzle is disposed on the surface of the polishing pad, and the polishing liquid after polishing is collected by being sucked by the suction nozzle from the surface of the polishing pad by the suction nozzle. The present invention relates to a polishing liquid recovery apparatus.

  In one aspect of the present invention, the suction nozzle can be disposed on the polishing pad on the downstream side of the polishing liquid with respect to the polishing head.

  In another aspect of the invention, the suction nozzle may be disposed on the outer peripheral side with respect to the polishing head on the polishing pad.

  Furthermore, in still another aspect of the present invention, the suction nozzle has an outer peripheral point of the polishing head located on the most downstream side in the rotation direction of the polishing pad, and a straight line connecting a central point from the outer peripheral point. Thus, the polishing pad can be disposed at a position separated by 45 degrees or more in the rotation direction of the polishing pad.

  In another embodiment of the present invention, the suction nozzle may have a suction aperture of 1 mm to 20 mm.

  According to the said aspect, the objective of this invention can be show | played more effectively.

  According to the present invention, there is provided a polishing liquid recovery method and recovery apparatus that efficiently recovers a polishing liquid (slurry) used for chemical mechanical polishing and that is not affected by contaminants around the polishing apparatus. be able to.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram schematically showing a configuration of a chemical mechanical polishing apparatus including a polishing liquid (slurry) recovery device of the present invention, and FIG. 2 is a schematic configuration diagram showing an enlarged portion of the recovery device. 3 and 4 are views showing the arrangement positions of the suction nozzles in the polishing liquid recovery apparatus shown in FIGS.

  As shown in FIG. 1, a chemical mechanical polishing apparatus 10 shown in this example includes a polishing surface platen (platen) 11, a polishing pad 12 affixed on the main surface, and placed on the polishing pad 12. The polishing head 13, the suction nozzle 14 disposed so that the suction port 14 </ b> A substantially contacts the polishing pad 12, and the polishing liquid disposed such that the supply port 15 </ b> A is located above the polishing pad 12 ( Slurry) supply pipe 15.

The polishing liquid supply pipe 15 is connected to the polishing liquid storage tank 17, and for example, a pressurization system that supplies the polishing liquid L onto the polishing pad 12 by an N ₂ pressurization system (not shown) can be used.

  The substrate S is disposed between the polishing pad 12 and the polishing head 13 so as to be pressed by the polishing head 13 and supplied to the polishing process described below.

  As shown in FIG. 2, the other end of the suction nozzle 14 is connected to the polishing liquid recovery tank 18, and the polishing liquid L sucked by the suction nozzle 14 is stored in the polishing liquid recovery tank 18 and then not shown. It is sucked into the pipe 19 by a pump and supplied to a processing apparatus (not shown).

  As shown in FIGS. 3 and 4, the suction nozzle 14 is located on the polishing pad 12 on the downstream side of the polishing liquid L with respect to the polishing head 13. Further, it is located on the polishing pad 12 on the outer peripheral side with respect to the polishing head 14. The polishing liquid (slurry) after polishing can be recovered more effectively and efficiently.

  Further, on the polishing pad 12, the suction nozzle 14 has an outer peripheral point of the polishing head 13 located on the most downstream side in the rotation direction of the polishing pad 12, and a straight line connecting the center point O1 from the outer peripheral point. The polishing pad is positioned at a distance of 45 degrees or more in the rotation direction. This is in consideration of the space in which the polishing head 14 is movable, and it is difficult to install the suction nozzle 14 in the vicinity of 45 degrees.

  In the example shown in FIG. 3, the suction port 14 </ b> A of the suction nozzle 14 is linear, and in the example shown in FIG. 4, the suction port 14 </ b> A of the suction nozzle 14 has an arc shape along the outer peripheral shape of the polishing pad 12. Is formed. In either case of FIG. 3 and FIG. 4, the polishing liquid supplied onto the polishing pad 12 can be efficiently recovered.

  Moreover, it is preferable that the width | variety of the front-end | tip part of 14 A of suction openings of the suction nozzle 14 is 1-20 mm. If the width of the tip portion of the suction port 14A is smaller than 1 mm, the used polishing liquid L cannot be sufficiently sucked and the polishing liquid L cannot be sufficiently collected. If the diameter of the suction port 14A is larger than 20 mm, the recovery efficiency of the polishing liquid L can no longer be affected, and conversely, the size occupied on the polishing pad 12 increases, which hinders the polishing process. there is a possibility.

  Next, a polishing method using a polishing apparatus including the polishing liquid recovery apparatus shown in FIGS.

First, as described above, the substrate S is sandwiched between the polishing pad 12 and the polishing head 13, and the substrate S is pressed with a predetermined pressure P by the polishing head 13. Next, the polishing liquid L is supplied from the polishing liquid storage tank 17 to the polishing pad 12 through the polishing liquid supply pipe 15 through the supply port 15A by N ₂ pressurization.

  Next, as indicated by an arrow in the figure, the polishing pad 12 is rotated counterclockwise from the center O1 as a base point, and the polishing head 13 is also rotated counterclockwise from the center O2 as a base point. As a result, the convex portions of the surface of the substrate S are gradually removed by the chemical reaction by the polishing liquid L and the mechanical polishing of the polishing pad 12 and the polishing head 13, and the substrate S is flattened.

  At this time, the polishing liquid L after polishing is located on the polishing pad 12 on the downstream side of the polishing liquid L with respect to the polishing head 13 and on the outer peripheral side with respect to the polishing head 13, and on the polishing pad 12, The outer peripheral point of the polishing head 13 is located on the most downstream side in the rotational direction of the polishing pad 12, and is separated from the straight line connecting the center point O1 by 45 degrees or more in the rotational direction of the polishing pad 12 with respect to the straight line. Suction is performed by the suction nozzle 14 located. Therefore, the used polishing liquid L can be efficiently sucked by the suction nozzle 14.

  As described above, the suctioned polishing liquid L is stored in the polishing liquid recovery tank 18 and then sucked into the pipe 19 by a pump (not shown) and supplied to a processing apparatus (not shown).

  In the polishing process of this example, unlike the conventional CMP method, the slurry after polishing is directly sucked from the polishing pad 12 and drained without flowing from the periphery of the polishing platen 11 to the drain of the polishing apparatus. It is sent to the processing facility and collected. Therefore, the polishing apparatus is not affected by contaminants collected around the polishing surface plate 11.

  In addition, after polishing the substrate S, the substrate S is washed with wafer rinsing water, dressing water, or the like. In this example, the used polishing liquid L is directly sucked from the polishing pad 12 to be contained in the polishing liquid storage tank 18. The wafer rinsing water, the dressing water, and the like are introduced into another waste water treatment apparatus (not shown) different from the polishing liquid storage tank 18 through the drain port around the polishing surface plate 11. Therefore, since the recovered polishing liquid L is not diluted with water, even when the recovered polishing liquid L is used for polishing again, it is almost unnecessary to adjust the concentration, and the slurry can be recycled efficiently. Will be able to.

  In order to improve the flattening effect by the CMP process, the pressure on the polishing head 13, the rotation speed of the polishing head 13 and the polishing surface plate (polishing pad) 11, the flow rate of the polishing liquid L, Process parameters such as the chemical composition of the abrasive grains in the polishing liquid, the process temperature, and the material of the polishing pad 12 can be adjusted.

  As general conditions, silica particles, alumina particles, or the like can be used as the abrasive grains in the polishing liquid. Moreover, the density | concentration of the abrasive grain in the polishing liquid L can be made into the range of 1 to 15 weight%, for example. Further, the polishing liquid L can contain an oxidizing agent or the like as necessary. This oxidizing agent has an effect of improving the polishing efficiency when a metal film or the like is formed on the surface of the substrate S. Such an oxidizing agent can be 3 volume% at the maximum of the amount of the polishing liquid L, for example.

  Next, based on an Example, this invention is demonstrated concretely. In this embodiment, as shown in FIG. 5, the position of the suction nozzle 14 (suction port) 14A with respect to the polishing pad 12 is changed in the range of (1) to (6), and how the suction amount is changed at that time. We investigated whether it changed to. In this example, in order to easily examine the effects of the present invention, an experiment was conducted using ordinary water instead of the polishing liquid.

A polishing pad 12 having a diameter of 15 inches was used, the suction air volume by the suction nozzle 14 was 3.1 m ³ / min, the suction pipe was 32 mm in diameter, and the water supply flow rate was 60 ml / min. The results are shown in Table 1.

  As is clear from Table 1, in all cases shown in FIG. 5, a high recovery rate is shown, but it can be seen that the recovery rate is the highest at the positions shown in FIGS. 5 (1) and (3). This is because the suction nozzle 14 (suction port 14 </ b> A) is closest to the polishing head 14 in the rotation direction. On the other hand, as shown in FIGS. 5 (2) and (4) to (6), it can be seen that the recovery rate decreases as the suction nozzle 14 (suction port 14A) moves away from the rotation direction of the polishing head 14. In addition, test No. of Table 1 Corresponds to the modes of FIGS. 5 (1) to (6).

  In comparison with FIGS. 5 (1) and 5 (3), in FIG. 5 (3), the outer peripheral point of the polishing head 13 is located on the most downstream side in the rotation direction of the polishing pad 12, and It is more preferable because it is positioned at a distance of 45 degrees or more in the rotation direction of the polishing pad with respect to a straight line connecting the center point to the point, and a space in which the polishing head 13 is movable is taken into consideration.

  The present invention has been described in detail with specific examples. However, the present invention is not limited to the above contents, and various modifications and changes can be made without departing from the scope of the present invention.

  For example, a recovery ring is disposed on the outer periphery of the polishing pad 12 and the recovery ring is inclined so that the used polishing liquid is collected in the recovery ring, and then the collected polishing liquid is sucked into the suction nozzle 14. It is also possible to suck and collect all at once. In this case, the recovery efficiency of the polishing liquid can be further improved.

It is a figure which shows roughly the structure of the chemical mechanical polishing apparatus containing the collection | recovery apparatus of the polishing liquid (slurry) of this invention. It is a schematic block diagram which expands and shows the part of the collection | recovery apparatus contained in the grinding | polishing apparatus of FIG. It is a figure which shows the arrangement position of the suction nozzle in the collection | recovery apparatus of the polishing liquid shown in FIG. Similarly, it is a figure which shows the arrangement position of the suction nozzle in the collection | recovery apparatus of the polishing liquid shown in FIG.1 and 2. FIG. It is a figure which shows the positional relationship of the polishing pad and suction nozzle (suction port) in an Example.

Explanation of symbols

10 Chemical mechanical polishing equipment 11 Polishing surface plate (platen)
DESCRIPTION OF SYMBOLS 12 Polishing pad 13 Polishing head 14 Suction nozzle 15 Polishing liquid supply pipe 17 Polishing liquid storage tank 18 Polishing liquid storage tank 19 Piping

Claims (10)

A substrate is disposed between a polishing pad and a polishing head, a polishing liquid is supplied, and the surface of the substrate is polished by a relative rotational movement between the polishing pad and the polishing head. A collection method,
A method for recovering a polishing liquid, wherein the polishing liquid after polishing is sucked and recovered from the surface of the polishing pad by a suction nozzle.   2. The polishing liquid recovery method according to claim 1, wherein the suction nozzle is disposed on the polishing pad on a downstream side of the polishing liquid supply unit with respect to the polishing head. 3.   The method for recovering a polishing liquid according to claim 1, wherein the suction nozzle is disposed on an outer peripheral side of the polishing head on the polishing pad.   The suction nozzle has an outer peripheral point of the polishing head located on the most downstream side in the rotation direction of the polishing pad on the polishing pad, and the polishing pad with respect to a straight line connecting a central point from the outer peripheral point. The method for recovering a polishing liquid according to claim 1, wherein the polishing liquid is disposed at a position separated by 45 degrees or more in the rotation direction.   The method for recovering a polishing liquid according to claim 1, wherein the suction nozzle has a suction aperture of 1 mm to 20 mm. A substrate is disposed between a polishing pad and a polishing head, a polishing liquid is supplied, and the surface of the substrate is polished by a relative rotational movement between the polishing pad and the polishing head. A recovery device,
A suction nozzle is disposed on the surface of the polishing pad, and the polishing liquid after polishing is collected by being sucked by the suction nozzle from the surface of the polishing pad by the suction nozzle. , Polishing liquid recovery device.   The polishing liquid recovery apparatus according to claim 6, wherein the suction nozzle is disposed on the polishing pad downstream of the polishing liquid supply unit with respect to the polishing head.   8. The polishing liquid recovery apparatus according to claim 6, wherein the suction nozzle is disposed on the outer peripheral side of the polishing head on the polishing pad.   The suction nozzle has an outer peripheral point of the polishing head located on the most downstream side in the rotation direction of the polishing pad on the polishing pad, and the polishing pad with respect to a straight line connecting a central point from the outer peripheral point. The polishing liquid recovery apparatus according to any one of claims 6 to 8, wherein the polishing liquid recovery apparatus is disposed at a position separated by 45 degrees or more in the rotation direction.   10. The polishing liquid recovery apparatus according to claim 6, wherein the suction nozzle has a suction diameter of 1 mm to 20 mm.

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