JP2010042497A - Wafer rotation stabilization structure in polishing head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide wafer rotation stabilization structure in a polishing head for executing a desired residual film thickness profile control by performing effective local pressing by bringing zone pressing parts into direct contact with a rear face of a wafer during polishing, and by properly averaging rotation of the wafer without causing a considerable increase of cost. <P>SOLUTION: This wafer rotation stabilization structure includes the zone pressing parts 10A, 10B and 10C for performing the local pressing by being brought into direct contact with the rear face of the wafer. Fluororesin coating is applied to contact parts for the rear face of the wafer in the zone pressing parts 10A, 10B and 10C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wafer rotation stabilization structure in a polishing head, and in particular, in a chemical mechanical polishing (CMP) or the like, a zone pressing portion is directly brought into contact with the back surface of a wafer to perform local pressing. The present invention relates to a wafer rotation stabilization structure in a polishing head capable of appropriately averaging wafer rotation and performing desired residual film thickness profile control.

  Conventionally, for example, the following polishing apparatus is known. In this prior art, an elastic mat is attached to the lower surface of the top ring (polishing head) to form a holding surface for holding the back surface of the wafer, which is an object to be polished, and the periphery of the wafer is surrounded by the elastic mat. An annular holding part for holding the part is formed. The outer peripheral portion of the wafer is held by the annular holding portion, and the wafer is held on a holding surface formed by an elastic mat. The top ring is provided with a pressing means for variable top ring that presses the held wafer against the polishing cloth on the turntable (platen). In the top ring, a circular first chamber located at the center, an annular second chamber located on the outer peripheral side of the first chamber, and an annular third chamber located on the outer peripheral side of the second chamber A pressurized fluid source is connected to each of the first to third chambers via valves. On the other hand, a plurality of openings for ejecting pressurized fluid from the first to third chambers to the holding surface of the wafer are opened through the elastic mat. Then, the pressure of the pressurized fluid supplied to each of the first to third chambers is changed to create a pressure gradient in the fluid interposed between the holding surface of the top ring and the back surface of the wafer, and press the wafer against the polishing cloth. By applying a gradient to the pressure, the excess or deficiency of the local polishing amount of the wafer is corrected.

  Further, a pressing ring is disposed on the outer periphery of the top ring so as to be movable up and down with respect to the top ring. The pressing ring is provided with a ring pressing means with variable pressing force. And, during the polishing, the pressing ring presses the polishing cloth appropriately, according to the pressing force the top ring presses the wafer against the polishing cloth, from the center of the wafer to the peripheral part, and further The polishing pressure up to the outer periphery of the pressure ring outside the wafer is continuous and uniform. For this reason, excessive or insufficient polishing amount at the peripheral edge of the wafer can be prevented (see, for example, Patent Document 1).

Conventionally, for example, the following wafer polishing apparatus is known. In this prior art, an air guide groove is formed along the circumferential direction on the outer peripheral side of the bottom surface of the carrier holding the wafer, and a plurality of air ejection holes are provided in the air guide groove at predetermined intervals in the circumferential direction. Is formed. Then, air is ejected from the plurality of air ejection holes to form a pressure air layer between the bottom surface of the carrier and the wafer while allowing the air to flow out of the carrier, and from the airbag transmitted to the carrier. Is transmitted to the wafer through the pressure air layer, whereby the wafer is pressed against the polishing pad for polishing. The plurality of air ejection holes communicate with each other through an air guide groove, and the air ejected from each air ejection hole is guided by the air guide groove and quickly supplied to the entire outer periphery of the wafer, An air layer is formed. As described above, when air is supplied to the outer peripheral portion of the wafer through the air guide groove, the air pressure applied to the wafer becomes uniform over the entire surface of the wafer, so that the wafer can be polished with a uniform pressing force (for example, , See Patent Document 2).
Japanese Patent No. 3795128. Japanese Patent No. 2940614.

  In the prior art described in Patent Document 1, the outer peripheral portion of the wafer is held by an annular holding portion formed at the bottom of the top ring, and the wafer is rotated by directly applying torque to the wafer by the rotation of the holding portion. Yes. Here, in the polishing of the wafer, in order to improve the polishing rate uniformity particularly in the peripheral portion of the wafer, it is essential to average the rotation speed of the wafer. On the other hand, in the case of the structure in which the torque is directly applied to the wafer by the rotation of the holding unit as described above and the rotation of the wafer is synchronized with the rotation of the holding unit, the rotation of the wafer depends on the processing accuracy of the holding unit. However, in order to increase the processing accuracy, productivity is lowered for that purpose, and time and equipment for accuracy inspection such as smoothness are required, resulting in high costs. Further, in this prior art, first to third chambers are provided in the top ring, and a pressurized fluid source is connected to each chamber via a valve, and the holding surface of the top ring, the upper surface of the wafer, In addition, a pressure gradient is given to the fluid itself intervening between them, and a gradient is given to the pressing force that presses the wafer against the polishing cloth, thereby correcting the excess or deficiency of the local polishing amount of the wafer. Further, in this prior art, a pressing ring is arranged on the outer periphery of the top ring so as to be movable up and down, and the pressing force that presses the polishing cloth is changed to the pressing force that the top ring presses the wafer against the polishing cloth. By adjusting accordingly, excessive or insufficient polishing amount at the peripheral edge of the wafer is prevented. In this way, the first to third chambers are provided in the top ring, and the press ring is disposed on the outer periphery of the top ring, which further increases the cost.

  Moreover, in the prior art described in Patent Document 2, the pressing force from the airbag transmitted to the carrier is transmitted to the wafer via the pressure air layer formed on the bottom surface of the carrier, thereby making the wafer uniform. The pressure is applied to polish.

  By the way, the polishing uniformity of the wafer in CMP can be achieved by uniform pressing of the wafer through the pressure air layer as described above and averaging of the rotation speed. The wafer rotation is averaged by setting the inner diameter of the retainer ring to a required diameter larger than the diameter of the wafer, and rotating the wafer asynchronously with respect to the rotation of the retainer ring. It is considered to achieve at a low cost without depending on the processing accuracy of the retainer ring. The technique of rotating the wafer asynchronously with respect to the rotation of the retainer ring to average the rotation speed of the wafer is described in the specification and drawings attached to the application of Japanese Patent Application No. 2008-104039 relating to the applicant's patent application. Is disclosed.

  However, in recent years, the positioning of CMP in the semiconductor device manufacturing process has shifted to profile control of the remaining film thickness of the wafer. It is difficult to achieve with the uniform pressure method in which the wafer is transmitted to the wafer through the substrate. For this reason, there is a need for a polishing head that is provided with a zone pressing portion and that can make local pressing by directly contacting the zone pressing portion with the back surface of the wafer. However, when the zone pressing portion is brought into direct contact with the back surface of the wafer, there is a problem that frictional resistance is generated and it becomes difficult to average the wafer rotation by the driven rotation due to the asynchronous rotation.

  Therefore, at the time of polishing, the zone pressing part is brought into direct contact with the back surface of the wafer to perform effective local pressing and appropriately average the rotation of the wafer without incurring a particularly high cost, thereby controlling the desired remaining film thickness profile. A technical problem to be solved in order to be executed arises, 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 polishing head for polishing a wafer by pressing the wafer against a polishing pad on a platen and rotating the wafer relative to the platen. The wafer rotation stabilization structure in FIG. 1 includes a zone pressing portion that directly contacts the back surface of the wafer and performs local pressing, and the contact portion of the zone pressing portion that contacts the wafer back surface is coated with a fluorine-based resin. Provided is a wafer rotation stabilization structure in a polished polishing head.

  According to this configuration, the wafer is asynchronous with respect to the rotation of the polishing head by pressing the zone pressing part, which is coated with a fluororesin coating having excellent slipperiness, in direct contact with the back surface of the wafer. Even if it rotates, the frictional resistance is suppressed to a minimum, and desired local pressing is effectively performed without hindering the rotation of the wafer. This makes it possible to perform desired residual film thickness profile control.

  A second aspect of the present invention provides the wafer rotation stabilization structure in the polishing head according to the first aspect, wherein the zone pressing portion is formed in a ring shape with the rotation center of the polishing head as a ring center. To do.

  According to this configuration, it is possible to reliably apply an effective local pressure to the annular zone having a desired radius on the wafer, and it is possible to reliably perform a desired residual film thickness profile control.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the zone pressing portion is composed of a plurality of ring-shaped zone pressing portions formed concentrically, and adjacent ring-shaped zone pressing portions. Provided is a wafer rotation stabilization structure in a polishing head in which an air guide groove is formed between and a plurality of air ejection holes are provided at appropriate intervals in the air guide groove.

  According to this configuration, by providing a plurality of ring-shaped zone pressing portions, it is possible to reliably apply effective local pressing to each annular zone having a plurality of desired radii on the wafer. In addition, the compressed air supplied from the air ejection holes quickly spreads between adjacent ring-shaped zone pressing portions via the air guide groove, and a pressure air layer is formed on the wafer to which the local pressing is applied. Between each annular zone is pressed by the pressure air layer. Therefore, it is possible to reliably perform desired residual film thickness profile control.

  According to a fourth aspect of the present invention, in the third aspect of the invention, a plurality of zone air grooves are formed in each ring-shaped zone pressing portion in the same direction as the radial direction of the polishing head, The zone air groove provides a wafer rotation stabilization structure in the polishing head that communicates with the air guide groove.

  According to this configuration, the compressed air supplied from the air ejection holes is also distributed to the zone air grooves formed in the respective zone pressing portions, so that the pressurization region by the pressure air layer is increased on the wafer. In addition to this, effective local pressing is surely performed on each annular zone having a plurality of desired radii on the wafer, so that desired residual film thickness profile control can be reliably performed. Further, since the plurality of zone air grooves and the air guide grooves communicate with each other, the both grooves also function as exhaust passages for the compressed air supplied from the air ejection holes. It is discharged to the outside appropriately through the road.

  According to a fifth aspect of the present invention, in the first, second, third, or fourth aspect of the invention, the inner diameter of the retainer ring provided on the polishing head side so as to surround the periphery of the wafer is longer than the diameter of the wafer. The diameter of the wafer is set to a large diameter, and the wafer provides a wafer rotation stabilization structure that is driven and rotated by rolling contact with the inner periphery of the retainer ring.

  According to this configuration, by setting the inner diameter of the retainer ring to be larger than the diameter of the wafer by a required length, when the polishing head rotates, the outer periphery of the wafer and the inner periphery of the retainer ring are Rolling contact occurs such that the contact position is sequentially shifted by a required amount. Then, by such rolling contact, the wafer rotates asynchronously with the rotation of the retainer ring, and the rotation speed is averaged.

  The invention described in claim 1 can effectively perform desired local pressing on the wafer, and properly maintain the rotation of the wafer even when the wafer rotates asynchronously with the rotation of the polishing head. Can do. Therefore, desired residual film thickness profile control can be executed. In addition, there is an advantage that the zone pressing portion is reduced in wear and can contribute to an improvement in life.

  The invention according to claim 2 is advantageous in that it can effectively apply the local pressure to the annular zone of the desired radius on the wafer, and the desired residual film thickness profile control can be executed reliably.

  The invention according to claim 3 can effectively apply a local pressure to each annular zone of a plurality of desired radii on the wafer, and can apply a pressure air layer between each annular zone. Thus, there is an advantage that the desired remaining film thickness profile control can be more reliably executed.

  The invention according to claim 4 has an advantage that uniform pressurization by the air layer can be maintained on the area other than the local press area on the wafer, and the control range of the desired residual film thickness profile control can be expanded. .

  According to the fifth aspect of the present invention, a rolling contact is generated between the outer peripheral portion of the wafer and the inner peripheral portion of the retainer ring so that the contact position sequentially shifts by a required amount. Rotates asynchronously. Accordingly, there is an advantage that the rotation of the wafer can be averaged without depending on the processing accuracy of the retainer ring which is expensive.

  Executes the desired residual film thickness profile control by bringing the zone pressing part into direct contact with the back surface of the wafer during polishing for effective local pressing and properly averaging the rotation of the wafer without incurring a particularly high cost. In order to achieve the above object, a wafer rotation stabilization structure in a 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, and directly contacts the back surface of the wafer. This is achieved by providing a zone pressing part that performs local pressing and applying a fluorine-based resin coating to the contact part of the zone pressing part to the wafer back surface.

  Hereinafter, a wafer rotation stabilization structure in a polishing head according to an embodiment of the present invention will be described in detail with reference to the drawings. 1 is a perspective view of a wafer polishing apparatus having a wafer rotation stabilization structure in a polishing head, FIG. 2 is a schematic enlarged longitudinal sectional view of a polishing head having a wafer rotation stabilization structure, and FIG. 3 is a view of the polishing head in FIG. The bottom view of a zone press part part, FIG. 4 are the figures which expand and show the part of a zone press part, (a) is a longitudinal cross-sectional view, (b) is a side view.

  First, the configuration of a wafer polishing apparatus having a wafer rotation stabilization structure in the polishing head will be described. In FIG. 1, a wafer polishing apparatus (CMP apparatus) 1 is mainly composed of a platen 2 and a 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 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 polishing head 3. Further, the 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 polishing head 3 is mainly composed of a head body 7, a back plate 8, a ring-shaped back plate airbag 9, a zone pressing portion 10, a retainer ring 11, and a ring-shaped retainer ring airbag 13. And control means such as air. The back plate airbag 9 and the retainer ring airbag 13 are connected to an air supply mechanism (not shown) for supplying air.

  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 back plate 8 is formed in a disc shape, and is disposed below the center of the head body 7. A dry plate 14 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 14 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 15 is provided on the periphery 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 15. . The zone pressing portion 10 that directly contacts the back surface of the wafer being polished and locally presses the wafer is fixed to the lower surface of the back plate 8. The zone pressing part 10 is made of a rubber material or the like, and as shown in the configuration example of FIG. 3, the outer side zone pressing part 10A formed in a ring shape with the rotation center of the polishing head 3 as the ring center, The intermediate zone pressing portion 10B and the inner zone pressing portion 10C are constituted by three pieces.

  Since these zone pressing portions 10A, 10B, and 10C are in direct contact with the back surface of the wafer being polished, when the wafer rotates asynchronously with the rotation of the polishing head 3, the rotation of the wafer is inhibited by frictional resistance. become. For this reason, as shown in FIG. 4 (a), the contact portions of the zone pressing portions 10A, 10B, and 10C with respect to the wafer back surface are made of a fluorine-based material such as polytetrafluoroethylene having excellent mechanical properties and slipperiness. A resin coating 16 is applied. The fluororesin coating 16 functions as a wafer rotation stabilization structure that minimizes frictional resistance even when the wafer rotates asynchronously with the rotation of the polishing head 3. The fluororesin coating 16 may be applied to at least contact portions of the zone pressing portions 10A, 10B, and 10C with respect to the wafer back surface, and must be performed in an air guide groove or a zone portion air groove described later. There is no.

  Air guide grooves 17a and 17b are formed between the outer peripheral zone pressing portion 10A and the intermediate zone pressing portion 10B and between the intermediate zone pressing portion 10B and the inner zone pressing portion 10C, respectively. A plurality of air ejection holes 18 for injecting compressed air are provided at appropriate intervals on the bottom surface portion of the back plate 8 along the inner peripheral edge of the inner zone pressing portion 10 </ b> C in 17 a and 17 b. The plurality of air ejection holes 18 in the air guide groove 17a, the plurality of air ejection holes 18 in the air guide groove 17b, and the plurality of air ejection holes 18 along the inner periphery of the inner zone pressing portion 10C are all air ejection. An air float line (not shown) for supplying compressed air is connected to each of the holes 18 for each of the plurality of air ejection holes 18 in the air guide groove 17a and the plurality of air ejection holes 18 in the air guide groove 17b.

  In addition to the arrangement of the plurality of air ejection holes 18, a vacuum hole leading to a vacuum line (not shown) is provided at an appropriate portion of the lower surface of the back plate 8 such as in the air guide groove 17b. The plurality of air ejection holes 18 may be switched and connected to the air float line and the vacuum line by a valve or the like, and the plurality of air ejection holes 18 may also be used as the vacuum holes. Supply of compressed air from the air float line, vacuum action from the vacuum line, and the like are executed by a command signal from the control unit.

  As shown in the bottom view of the zone pressing portion of FIG. 3 and the enlarged side view of FIG. 4B, each of the zone pressing portions of the outer zone pressing portion 10A, the intermediate zone pressing portion 10B, and the inner zone pressing portion 10C. On the lower surface side, a plurality of zone air grooves 19 are formed in the same direction as the radial direction of the polishing head 3. The plurality of zone air grooves 19 communicate with the air guide grooves 17a and 17b and the inner peripheral edge side space of the inner zone pressing portion 10C. As described above, the plurality of zone air grooves 19 formed in each of the zone pressing portions 10A, 10B, and 10C and the air guide grooves 17a and 17b communicate with each other so that the grooves 19 and 17a and 17b are plural. This also functions as an exhaust path for compressed air ejected from the air ejection holes 18, and the ejected compressed air is appropriately discharged to the outside through the exhaust path.

  The retainer ring 11 is formed in a ring shape whose inner diameter is larger than the diameter of the wafer (for example, 300 mm) by a required length (for example, at least 3 mm), and is disposed on the outer periphery of the back plate 8. Thus, by setting the inner diameter of the retainer ring 11 to be larger than the diameter of the wafer by the required length, the outer periphery of the wafer is driven by rolling contact with the inner periphery of the retainer ring 11. It rotates asynchronously with the rotation of the retainer ring 11.

  The retainer ring 11 is attached to a retainer ring holder 20 provided in the polishing head 3, and a retainer ring pressing member 22 is connected to the retainer ring holder 20 via a snap ring 21. A snap ring cover 23 is attached to the outer periphery of the snap ring 21. The retainer ring 11 is pressed against the polishing pad 6 by receiving a pressing force from the retainer ring airbag 13 via the retainer ring pressing member 22 and the like.

  Next, the operation of the wafer rotation stabilization structure in the polishing head configured as described above will be described. First, the 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 polishing head 3 is activated, and the wafer is attracted to the lower surface of the back plate 8. Then, the polishing mechanism 3 that sucks and holds the wafer 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.

  Next, the operation on the vacuum line side is released, and air is supplied from the air supply mechanism (not shown) to the back plate airbag 9 and the retainer ring airbag 13 to inflate both airbags 9 and 11. At the same time, compressed air is supplied from the air ejection holes 18 into the air guide grooves 17a and 17b, to the inner peripheral edge side space of the inner zone pressing portion 10C, and to the zone air grooves 19, and pressure is applied to these portions. An air layer is formed.

  Thereby, the retainer ring 11 is pressed against the polishing pad 6 by the swelling of the retainer ring airbag 13. Further, due to the pressing force of the back plate 8 due to the expansion of the back plate air bag 9, the outer peripheral side zone pressing portion 10A, the intermediate zone pressing portion 10B, and the inner zone pressing portion 10C are in direct contact with the back surface of the wafer, and each zone pressing portion. Local pressing is applied to each annular zone on the wafer corresponding to 10A, 10B, and 10C, and further, between each annular zone and the like is pressed via a pressure air layer.

  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 to supply slurry from a nozzle (not shown) onto the rotating polishing pad 6. Since the inner diameter of the retainer ring 11 is set to be larger than the diameter of the wafer by a required length, when the polishing head 3 rotates, there is a gap between the outer periphery of the wafer and the inner periphery of the retainer ring 11. Then, rolling contact occurs such that the contact position is sequentially shifted by a required amount. Due to this rolling contact, the rotation speed of the wafer increases in inverse proportion to the ratio of the inner diameter of the retainer ring 11 and the diameter of the wafer, and the wafer starts rotating asynchronously with the rotation of the retainer ring 11.

  At this time, the zone pressing portions 10A, 10B, and 10C that are in direct contact with the back surface of the wafer and apply local pressing are provided with a fluorine resin coating 16 having excellent slipperiness on the contact portions. Thus, even if the wafer rotates asynchronously with respect to the rotation of the retainer ring 11, the frictional resistance is suppressed to a minimum and the asynchronous rotation of the wafer is not hindered. As a result, the rotation speed of the wafer is appropriately averaged, and the desired local pressing is effectively performed by the zone pressing portions 10A, 10B, and 10C, so that the polishing proceeds, and the desired remaining film thickness profile control is performed. Surely done.

  In this embodiment, the air supply amount to the back plate air bag 9 is appropriately set so that the zone pressing portions 10A, 10B, 10C do not contact the back surface of the wafer by the pressing force transmitted to the back plate 8. By adjusting, the pressing force transmitted to the back plate 8 can be transmitted to the wafer via the pressure air layer, and the wafer can be polished in a state where the wafer is uniformly pressurized.

  As described above, in the wafer rotation stabilization structure in the polishing head according to the present embodiment, the inner diameter of the retainer ring 11 is set larger than the diameter of the wafer by a required length, so that the outer peripheral portion of the wafer and the retainer A rolling contact is generated between the inner periphery of the ring 11 so that the contact position sequentially shifts by a required amount, and the wafer rotates asynchronously with the rotation of the retainer ring 11. Thereby, the rotation of the wafer can be averaged without depending on the processing accuracy of the retainer ring, which is expensive.

  By applying the fluororesin coating 16 having excellent slipperiness to the wafer contact portions in the zone pressing portions 10A, 10B, and 10C, even if the wafer rotates asynchronously with the rotation of the retainer ring 11, the friction resistance Is kept to a minimum and does not hinder asynchronous rotation of the wafer. As a result, the rotation of the wafer can be properly averaged, and desired local pressing can be effectively performed on the wafer, and desired residual film thickness profile control can be executed. Moreover, each zone press part 10A, 10B, 10C can be made low-wearing and can contribute to lifetime improvement.

  A local pressure can be effectively applied to each annular zone on the wafer corresponding to each zone pressing portion 10A, 10B, 10C, and a pressure air layer can be applied between each annular zone, Desired remaining film thickness profile control can be executed more reliably.

  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 figure shows a wafer rotation stabilization structure in a polishing head according to an embodiment of the present invention.
The perspective view of a wafer polisher provided with the wafer rotation stabilization structure in a polish head. FIG. 2 is a schematic enlarged longitudinal sectional view of a polishing head equipped with a wafer rotation stabilization structure. The bottom view of the zone press part part in the grinding | polishing head of FIG. It is a figure which expands and shows the part of a zone press part, (a) is a longitudinal cross-sectional view, (b) is a side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wafer polisher 2 Platen 3 Polishing head 4 Rotating shaft 5 Motor 6 Polishing pad 7 Head main body 8 Backplate 9 Backplate airbag 10 Zone pressing part 10A Outer peripheral side zone pressing part 10B Middle zone pressing part 10C Inner zone pressing part 11 Retainer ring 12 Rotating shaft 13 Retainer ring air bag 14 Dry plate 15 Back plate pressing member 16 Fluorine resin coating 17a, 17b Air guide groove 18 Air ejection hole 19 Zone part air groove 20 Retainer ring holder 21 Snap ring 22 Retainer ring Press member 23 Snap ring cover

Claims (5)

A wafer rotation stabilization structure in a polishing head for pressing a wafer against a polishing pad on a platen and rotating the wafer relative to the platen to polish the wafer,
A wafer in a polishing head comprising a zone pressing portion that directly contacts the back surface of the wafer and performs local pressing, and a contact portion of the zone pressing portion that contacts the wafer back surface is coated with a fluorine resin. Rotation stabilization structure.   2. The wafer rotation stabilization structure in a polishing head according to claim 1, wherein the zone pressing portion is formed in a ring shape having the center of rotation of the polishing head as a ring center.   The zone pressing portion is composed of a plurality of ring-shaped zone pressing portions formed concentrically. An air guide groove is formed between adjacent ring-shaped zone pressing portions, and a plurality of zones are formed in the air guide groove. 3. The wafer rotation stabilization structure in a polishing head according to claim 1, wherein the air ejection holes are provided at appropriate intervals. 4.   Each of the ring-shaped zone pressing portions has a plurality of zone air grooves formed in the same direction as the radial direction of the polishing head, and the plurality of zone air grooves communicate with the air guide grooves. 4. A wafer rotation stabilization structure in a polishing head according to claim 3, wherein   The inner diameter of the retainer ring provided on the polishing head side so as to surround the periphery of the wafer is set to a required diameter larger than the diameter of the wafer, and the outer periphery of the wafer is the inner periphery of the retainer ring. 5. The structure for stabilizing the rotation of a wafer in a polishing head according to claim 1, wherein the structure is rotated by being brought into contact with rolling.

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