JP2010036284A - Polishing head having no contamination of metal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing head having no contamination of metal which can improve the quality of a wafer to be polished by preventing the exposure of metal to the wafer to be polished, preventing a metal ion dissolved in slurry from the metal from adhering to the wafer as a metal stain and assuredly fixing a wafer pressing air back to a lower surface of the head. <P>SOLUTION: In the polishing head having no contamination of metal, at least a part of a back plate 8 as a member forming the lower surface of the head which is exposed to the wafer is formed with a resin material. Pressing fittings 16a and 16b made of SUS and screws 17a and 17b made of SUS for attaching the air back 15 for applying a pressing force to the wafer to the lower surface of the back plate 8 are accommodated in the air back 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a metal contamination-free polishing head, and in particular, improves the quality of the wafer by preventing adhesion of metal ions to the wafer polished in chemical mechanical polishing (CMP) or the like. The present invention relates to a metal contamination-free polishing head.

  A configuration example of the back plate 25 portion in the conventional polishing head will be described with reference to FIG. In the figure, a back plate 25 is formed of a SUS material in a disc shape and is disposed at a lower central portion of the polishing head. On the lower surface of the back plate 25, there is provided a wafer pressing air bag 26 comprising a ring-shaped outer zone air bag 26A and an inner zone air bag 26B connected to the inner side. The airbag 26 is made of silicone rubber or the like, and the outer zone airbag 26A and the inner zone airbag 26B are attached to the lower surface of the back plate 25 as follows. That is, the outer peripheral edge of the outer zone airbag 26A is attached by the SUS presser fitting 27a and the SUS screw 28a, and the inner peripheral edge of the outer zone airbag 26A and the outer peripheral edge of the inner zone airbag 26B are the same. And the SUS screw 28b, and the inner peripheral edge of the inner zone airbag 26B is attached by a SUS presser fitting 27c and a SUS screw 28c. Dozens of attachment points by the SUS presser fittings 27a, 27b, 27c and the SUS screws 28a, 28b, 28c are provided in the circumferential direction. Among these SUS presser fittings 27a, 27b, and 27c and SUS screws 28a, 28b, and 28c, a part of the SUS presser fitting 27a and the SUS screw 28a, and the SUS presser fitting 27c and the SUS screw 28c, respectively, are part of the back plate 25. It is exposed on the lower surface side.

  An outer zone pressurization line (not shown) for supplying air is connected to the outer zone airbag 26A, and an inner zone pressurization line (not shown) for supplying air is connected to the inner zone airbag 26B. ing. The outer zone airbag 26A and the inner zone airbag 26B swell when supplied with air, and press the wafer against the polishing pad on the platen with a predetermined pressure.

  Further, as described above, as a conventional technique in which a resin material is associated with a polishing apparatus in which a metal member such as SUS is frequently used as a constituent member, for example, the following resin coating of a flat polishing apparatus is known. Yes. In this prior art, resin coating is applied to the lower surface plate side and the upper surface plate side of the flat polishing apparatus as follows. That is, with respect to the lower surface plate side, the lower surface plate and its base are coated with a resin coating on the entire periphery except for the abutting portion between them. Moreover, regarding the upper surface plate side, the upper surface plate and its base are coated with a resin coating on the entire periphery except for the abutting portion of both. And by giving resin coating in this way, generation | occurrence | production of the rust by an abrasive | polishing agent etc. is prevented and durability of an apparatus is made favorable (for example, refer patent document 1).

Furthermore, as another conventional technique, for example, the following CMP apparatus is known. In this prior art, at least one coating target selected from the group consisting of a head surface, an arm surface, a slurry supply pipe surface, and an inner wall of the main body of a CMP apparatus is coated with a fluorine resin, and the slurry adheres to these. In addition, a CMP apparatus that is easy to clean the fixed slurry and is excellent in chemical resistance is provided (see, for example, Patent Document 2).
JP 2000-79556 A. JP 2007-245266.

  In the configuration of the back plate portion in the conventional polishing head shown in FIG. 5, the lower surface of the back plate is formed by a SUS material back plate itself, a plurality of SUS presser fittings for attaching an air bag, and a part of the SUS screw. Since the metal member was exposed to the metal member, metal ions eluted from the metal member into the slurry or the like may adhere to the wafer to be polished as metal contamination, which may deteriorate the quality of the polished wafer. there were. On the other hand, if the presser fitting and screw for mounting the air bag are changed to one made of a resin material other than metal, the tightening torque at the time of mounting becomes insufficient, and fixing of the air bag to the lower surface of the back plate is not possible. There is a problem that the quality of the wafer to be polished is deteriorated in this respect.

  In the prior art described in Patent Document 1, resin coating is applied to the entire periphery of the lower surface plate side and the upper surface plate side so as to prevent the occurrence of rust on the entire periphery portion and is polished. There is no disclosure regarding the technique of preventing metal exposure to the wafer.

  In the prior art described in Patent Document 2, the surface of the head part and the surface of the slurry supply pipe in the CMP apparatus are covered with a fluororesin so as to reduce the adhesion of the slurry to these parts and facilitate cleaning. In the same manner as described above, it is not intended to prevent exposure of metal to a wafer to be polished.

  Therefore, metal exposure to the wafer to be polished is prevented, metal ions eluted from the metal in the slurry are prevented from adhering to the wafer as metal contamination, and an air bag for pressing the wafer is provided on the bottom surface of the head. Therefore, a technical problem to be solved in order to improve the quality of the wafer to be polished by being fixed to the part surely occurs, and the present invention aims to solve this problem.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is a metal contamination in which a wafer is pressed against a polishing pad on a platen and rotated relative to the platen to polish the wafer. A less polishing head, wherein at least a portion of the constituent member of the head lower surface portion exposed to the wafer is formed of a resin material, and an air bag for applying a pressing force to the wafer is formed on the constituent member of the head lower surface portion. Provided is a metal contamination-free polishing head in which mounting parts including metal screws for mounting are housed in the airbag.

  According to this configuration, since the constituent member of the lower surface portion of the head is formed of the resin material, the wafer to be polished is not exposed to the metal from the lower surface portion of the head. In addition, parts for mounting the airbag on the lower surface of the head, such as screws and presser fittings, are made of a metal material such as SUS in order to secure the tightening torque for mounting. By storing the components in the air bag, the metal material used for the air bag mounting component is not exposed to the wafer to be polished.

  According to a second aspect of the present invention, there is provided the metal contamination-less polishing head according to the first aspect, wherein the constituent member of the lower surface portion of the head is a back plate.

  According to this configuration, at least a portion of the back plate that occupies most of the area of the lower surface of the head is exposed to the wafer by the resin material, so that the metal exposed from the lower surface of the head is exposed to the wafer to be polished. Disappear.

  According to a third aspect of the present invention, there is provided the metal contamination-free polishing head according to the first or second aspect, wherein the air bag includes a continuous outer zone air bag and an inner zone air bag. .

  According to this configuration, the outer zone air bag and the inner zone air bag that are continuously provided as the air bag are applied, so that the number of metal mounting parts for mounting the air bag on the lower surface of the head is reduced. Will increase. On the other hand, all of these increased mounting parts are housed in the outer zone airbag and the inner zone airbag, so that the metal material used for all these mounting parts for the wafer to be polished. No exposure.

  A fourth aspect of the present invention provides the metal contamination-less polishing head according to the first or second aspect, wherein the air bag is concentrically provided with a plurality of zone air bags.

  According to this configuration, by appropriately adjusting the pressing force of each zone air bag, a desired pressing force distribution can be given to the wafer to be polished. And even if the number of parts for mounting parts made of metal material is increased in order to attach a plurality of zone airbags to the lower surface of the head, all these mounting parts are appropriately stored in the plurality of zone airbags, There is no exposure of the metal material used for all these mounting components to the wafer being polished.

  According to the first aspect of the present invention, there is no metal exposure from the lower surface of the head to the wafer to be polished, and there is no exposure of the metal material used for the parts for attaching the airbag. For this reason, there is no elution of metal ions from these metals in the slurry or the like used for polishing, and such metal ions do not adhere as metal contamination to the wafer to be polished. In addition, by using a metal part for the parts including the screw for attaching the airbag, a tightening torque for securing is secured and the airbag can be securely fixed to the lower surface of the head. Therefore, there is an advantage that the quality of the wafer to be polished can be improved.

  The invention according to claim 2 eliminates the metal exposure from the back plate which occupies most of the area of the lower surface of the head with respect to the wafer to be polished. For this reason, there is no elution of metal ions from the back plate in the slurry or the like, and such metal ions do not adhere as metal contamination to the wafer to be polished. Therefore, there is an advantage that the quality of the wafer to be polished can be further improved.

  According to a third aspect of the present invention, a wafer that is polished even when the number of metal mounting parts for mounting the outer zone airbag and the inner zone airbag connected to the lower surface of the head is increased. On the other hand, exposure of the metal material used for all these mounting parts can be eliminated. In addition, the outer zone airbag and the inner zone airbag that are continuously provided for pressing the wafer can be securely fixed to the lower surface of the head, and the wafer can be polished more appropriately. Therefore, there is an advantage that the quality of the wafer to be polished can be further improved.

  In the invention according to claim 4, even if the number of parts made of metal is increased because a plurality of zone airbags are attached to the lower surface of the head, all these parts are attached to the wafer to be polished. The exposure of the metal material used can be eliminated. In addition, a plurality of zone airbags can be securely fixed to the bottom surface of the head, and furthermore, a desired pressing force distribution can be obtained for a wafer to be polished by appropriately adjusting the pressing force of each zone airbag. Can be made. Therefore, there is an advantage that it is possible to obtain a wafer having no metal contamination, high quality, and a desired polishing profile.

  Prevents metal from being exposed to the wafer being polished, prevents metal ions eluting from the metal from adhering to the wafer as metal stains in the slurry, etc., and an air bag for pressing the wafer to the lower surface of the head Metal contaminationless polishing in which the wafer is pressed against the polishing pad on the platen and rotated relative to the platen to polish the wafer in order to achieve the objective of securing and improving the quality of the polished wafer A head, wherein at least a portion of the constituent member on the lower surface of the head exposed to the wafer is formed of a resin material, and an air bag for applying a pressing force to the wafer is attached to the constituent member of the lower surface of the head This was realized by housing a mounting part including a metal screw in the air bag.

  Hereinafter, a metal contamination-free polishing head according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a wafer polishing apparatus provided with a metal contamination-less polishing head, and FIG. 2 is a schematic enlarged longitudinal sectional view of the metal contamination-less polishing head.

  First, the configuration of a wafer polishing apparatus provided with a metal contamination-free polishing head will be described. In FIG. 1, a wafer polishing apparatus (CMP apparatus) 1 is mainly composed of a platen 2 and a metal contamination-free polishing head 3. The platen 2 is formed in a disk shape, and a rotary shaft 4 is connected to the center of the lower surface thereof. The platen 2 rotates in the direction of arrow A when the motor 5 is driven. A polishing pad 6 is affixed to the upper surface of the platen 2, and a slurry that is a mixture of an abrasive and a chemical is supplied onto the polishing pad 6 from a nozzle (not shown).

  The metal contamination-less polishing head 3 is provided so as to be movable up and down by a lifting device (not shown), and is moved upward when a wafer to be polished is set on the metal contamination-less polishing head 3. Further, the metal contamination-less polishing head 3 is moved downward and brought into contact with the polishing pad 6 when polishing the wafer.

  As shown in FIG. 2, the metal contamination-less polishing head 3 is mainly composed of a head body 7, a resin back plate 8, a ring-shaped back plate air bag 9, a retainer ring 10, and a ring-shaped retainer ring air bag. 11 and control means such as air. The back plate air bag 9 and the retainer ring air bag 11 are connected to an air supply mechanism (not shown) for supplying air. The back plate 8 only needs to be formed of a resin material on at least the lower surface exposed to the wafer to be polished.

  The head body 7 is formed in a disk shape smaller than the platen 2, and a rotary shaft 12 (see FIG. 1) is connected to the center of the upper surface thereof. The head body 7 is attached to the rotary shaft 12 and is driven by a motor (not shown) to rotate in the direction of arrow B in FIG.

  The resin back plate 8 is formed in a disc shape and is disposed below the center of the head body 7. A dry plate 13 is provided between the central portion of the upper surface of the back plate 8 and the central lower portion of the head body 7, and rotation is transmitted from the head body 7. An operation transformer (not shown) is disposed between the center lower portion of the dry plate 13 and the center upper portion of the back plate 8, and the operation transformer is connected to a control unit (not shown) and is formed on the wafer. The polishing state signal of the conductive film is output to the control unit.

  A ring-shaped back plate pressing member 14 is provided on the peripheral edge of the upper surface of the back plate 8, and the pressing force is transmitted from the back plate air bag 9 to the back plate 8 via the back plate pressing member 14. . Further, on the lower surface of the back plate 8, a wafer pressing air bag 15 including a ring-shaped outer zone air bag 15 </ b> A and an inner zone air bag 15 </ b> B connected to the inner side is provided.

  The airbag 15 is made of silicone rubber or the like, and the outer zone airbag 15A and the inner zone airbag 15B are attached to the lower surface of the back plate 8 as follows. That is, the outer zone airbag 15A is attached by a SUS presser fitting 16a and a SUS screw 17a screwed to the SUS presser fitting 16a from the back side of the back plate 8, and the inner zone airbag 15B has an outer peripheral edge. The SUS presser fitting 16a is attached in common and the inner peripheral edge is attached by a SUS presser fitting 16b and a SUS screw 17b. Dozens of attachment points by the SUS presser fittings 16a and 16b and the SUS screws 17a and 17b are provided in the circumferential direction.

  The order of attaching the outer zone airbag 15A and the inner zone airbag 15B to the lower surface of the back plate 8 will be described with reference to FIGS. 3 (a), 3 (b), and 3 (c). The inner periphery of the inner zone airbag 15B is attached with the SUS presser fitting 16b and the SUS screw 17b so that the entire airbag 15 is turned over. At this time, the SUS screw 17b can be firmly screwed by embedding a helicate or the like in advance in the screwing portion 8a of the SUS screw 17b (FIG. 3A). The outer zone air bag 15A is attached to the SUS presser fitting 16a by screwing the SUS screw 17a through a set screw hole 8b provided on the back side of the back plate 8 (FIG. 3B). A resin set screw 18 is screwed into the set screw hole 8b to cover the set screw hole 8b (FIG. 3C). By such an attachment method, the SUS presser fittings 16a and 16b and the SUS screws 17a and 17b are all housed in the air bag 15 and are not exposed to the wafer to be polished.

  An outer zone pressurization line 19 for supplying air is connected to the outer zone airbag 15A, and an inner zone pressurization line 20 for supplying air is connected to the inner zone airbag 15B. . The outer zone airbag 15 </ b> A and the inner zone airbag 15 </ b> B swell when supplied with air, and press the wafer against the polishing pad 6 on the platen 2 with a predetermined pressure.

  An air blowing port (not shown) for injecting compressed air between the lower surface of the back plate 8 and the wafer is provided on the lower surface of the center side of the back plate 8 (where the air bag 15 is not disposed). A vacuum hole leading to a vacuum line (not shown) is provided. The supply of compressed air to the lower surface of the center side of the back plate 8 and the vacuum action from the vacuum line are executed by a command signal from the control unit.

  The retainer ring 10 is formed in a ring shape and is disposed on the outer periphery of the back plate 8. The retainer ring 10 is attached to a retainer ring holder 21 provided in the metal contamination-free polishing head 3, and a retainer ring pressing member 23 is connected to the retainer ring holder 21 via a snap ring 22. A snap ring cover 24 is attached to the outer periphery of the snap ring 22. The retainer ring 10 is pressed against the polishing pad 6 by transmitting a pressing force from the retainer ring airbag 11 through the retainer ring pressing member 23 and the like.

  Next, the operation of the metal contamination-less polishing head configured as described above will be described. The outer zone airbag 15A and the inner zone airbag 15B are attached to the lower surface of the back plate 8 using metal parts such as SUS presser fittings 16a and 16b and SUS screws 17a and 17b. The tightening torque at the time is sufficiently secured and is securely fixed to the lower surface of the back plate 8.

  First, such a metal contamination-free polishing head 3 is placed on a waiting wafer at a predetermined location by a moving mechanism (not shown). Then, the vacuum line side of the metal contamination-less polishing head 3 is activated, and the wafer is adsorbed to the lower surface of the back plate 8 through the vacuum hole on the lower surface on the center side of the back plate 8. Then, the metal contamination-less polishing head 3 holding the wafer by suction is carried onto the platen 2 by the moving mechanism, and the wafer is placed on the platen 2 so that the conductive film to be polished contacts the polishing pad 6. Put.

  Next, the operation on the vacuum line side is released, and air is supplied to the back plate air bag 9 and the retainer ring air bag 11 from an air supply mechanism (not shown) to inflate both air bags 9 and 11. At the same time, air is supplied from the outer zone pressurization line 19 and the inner zone pressurization line 20 to the outer zone airbag 15A and the inner zone airbag 15B to inflate the outer and inner zone airbags 15A and 15B. Further, compressed air is supplied from the air outlet to the central lower surface space of the back plate 8 to form a pressure air layer in the central lower surface space of the back plate 8.

  As a result, the retainer ring 10 is pressed against the polishing pad 6 by the bulging of the retainer ring air bag 11, the pressing force of the back plate 8 by the bulge of the back plate air bag 9, the outer zone air bag 15 A and the inner zone air. Due to the swelling of the back 15B, the conductive film on the wafer is pressed against the polishing pad 6 with a predetermined pressure. In this state, the platen 2 is rotated in the direction of arrow A in FIG. 1 and the polishing head 3 is rotated in the direction of arrow B in FIG. 1, and slurry is supplied from a nozzle (not shown) onto the rotating polishing pad 6 to be polished. Polish the conductive film on the wafer.

  At this time, since the back plate 8 is made of a resin material, the wafer to be polished is not exposed to metal from the lower surface of the back plate 8. In addition, the presser fittings 16a and 16b and the screws 17a and 17b, both of which are made of SUS in order to secure the tightening torque at the time of mounting, are all housed in the air bag 15 and are polished on the wafer to be polished. It is unexposed to it. For this reason, there is no elution of metal ions from these metals in the slurry, and such metal ions do not adhere as metal contamination to the wafer to be polished.

  Next, a configuration example in which a plurality of (four in the example of FIG. 4) zone air bags are concentrically provided on the lower surface of the back plate 8 in the metal contamination-less polishing head will be described with reference to FIG. In this configuration example, a circular zone airbag 15D is continuously provided inside the inner zone airbag 15B shown in FIG. 2, and a ring-shaped zone airbag 15C is continuously provided further outside the outer zone airbag 15A. ing. Thus, on the lower surface of the back plate 8, the air bag 15 including the four zone air bags 15 </ b> A to 15 </ b> D concentrically provided is provided.

  The outer peripheral edge of the circular zone airbag 15D is commonly attached by a SUS retainer 16b and a SUS screw 17b, and the ring-shaped zone airbag 15C is attached to the SUS retainer 16c and the SUS retainer 16c. It is attached with a SUS screw 17c screwed from the back side of the back plate 8. In addition, zone pressure lines (not shown) for supplying air are respectively connected to the four zone airbags 15A to 15D.

  As shown in this configuration example, even if the number of zone air bags increases to four of 15A to 15D and the number of SUS presser fittings 16a to 16c and SUS screws 17a to 17c for attaching them increases, these All of the mounting parts are accommodated in the plurality of zone airbags 15A to 15D, and exposure of the metal material used for all these mounting parts to the wafer to be polished is eliminated. For this reason, there is no elution of metal ions from these metal materials in the slurry, and such metal ions do not adhere as metal contamination to the wafer to be polished.

  In addition, since the number of disposed zone airbags 15A to 15D is increased, by appropriately adjusting the pressing force of each of the zone airbags 15A to 15D, the wafer to be polished has a desired pressing force distribution. be able to. Therefore, it is possible to obtain a wafer having no metal contamination and high quality and a desired polishing profile.

  The circular zone airbag 15D may be arranged at an appropriate interval without being connected to the inner zone airbag 15B, and a plurality of zone airbags may be formed of wafers having a desired polishing profile. In obtaining, it is possible to appropriately change the arrangement position and the number thereof.

  As described above, in the metal contamination-less polishing head according to the present embodiment, there is no metal exposure from the lower surface portion of the back plate 8 to the wafer to be polished, and the SUS presser fitting 16a for attaching the air bag 15 is used. There is no exposure of the metal material used for ~ 16c and SUS screws 17a-17c. For this reason, there is no elution of metal ions from these metals in the slurry or the like, and such metal ions do not adhere as metal contamination to the wafer to be polished. Further, the SUS presser fittings 16a to 16c and the SUS screws 17a to 17c for attaching the air bag 15 are all made of a metal material, so that a tightening torque for the attachment is secured and the wafer pressing is performed. The air bag 15 can be securely fixed to the lower surface of the back plate 8. Therefore, the quality of the wafer to be polished can be improved.

  Since the helicate is pre-embedded in the screwing portion 8a of the SUS screw 17b for attaching the inner peripheral edge of the inner zone airbag 15B, the SUS screw 17b can be attached even if the back plate 8 is made of a resin material. The air bag 15 can be firmly screwed and the air bag 15 can be more securely fixed to the lower surface of the back plate 8.

  In the case where four zone airbags 15A to 15D are provided, a desired pressure distribution can be given to the wafer to be polished by appropriately adjusting the pressing force of each zone airbag 15A to 15D. A wafer having a desired polishing profile can be obtained.

  The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

The perspective view of the wafer polisher provided with the metal contamination-less polish head concerning the example of the present invention. FIG. 2 is a schematic enlarged longitudinal sectional view of the metal contamination-free polishing head in FIG. FIG. 3 is a longitudinal sectional view for explaining the mounting order of two outer and inner zone airbags on the lower surface of the back plate in the metal contamination-less polishing head of FIG. 2, and FIG. The figure which shows a state of screwing so that the entire back is turned, (b) is a figure showing the state of screwing the outer zone air bag retainer from the back side, and (c) is a resin fastening of the set screw hole from the back side The figure which shows a mode that it covers with a screw. FIG. 4 is a longitudinal sectional view showing a configuration example in which four zone airbags are concentrically provided on the lower surface of the back plate in the metal contamination-less polishing head according to the embodiment of the present invention. The longitudinal cross-sectional view of the backplate part in the conventional grinding | polishing head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wafer polisher 2 Platen 3 Metal-contamination-less polishing head 4 Rotating shaft 5 Motor 6 Polishing pad 7 Head body 8 Back plate 9 Back plate air bag 10 Retainer ring 11 Retainer ring air bag 12 Rotating shaft 13 Dry plate 14 Back plate Press member 15 Air bag 15A to 15D Zone air bag 16a to 16c SUS presser fitting 17a to 17c SUS screw 18 Resin set screw 19 Outer zone pressurization line 20 Inner zone pressurization line 21 Retainer ring holder 22 Snap ring 23 Retainer ring Pressing member 24 Snap ring cover

Claims (4)

A metal contamination-free polishing head that presses a wafer against a polishing pad on a platen and rotates the wafer relative to the platen to polish the wafer,
A part made of a metal material for attaching an air bag for applying a pressing force to the wafer on the constituent member of the head lower surface portion while forming at least a portion of the constituent member of the head lower surface portion exposed to the wafer with a resin material. A metal contamination-free polishing head, wherein mounting parts including screws are accommodated in the air bag.   2. The metal contamination-less polishing head according to claim 1, wherein the constituent member of the lower surface portion of the head is a back plate.   3. The metal contamination-free polishing head according to claim 1, wherein the air bag is composed of an outer zone air bag and an inner zone air bag provided in series.   The metal contamination-free polishing head according to claim 1 or 2, wherein the air bag has a plurality of zone air bags arranged concentrically.

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