JP2005019440A - Work holding head and polishing device having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a work holding head with which the whole surface of a wafer can be polished uniformly for a long time by preventing the outer peripheral edge of the wafer from being polished excessively, and to provide a polishing device having the work holding head. <P>SOLUTION: Such work holding head 14 in the polishing device is provided that presses a work W against a polishing pad 20 while holding the work W when the work W is polished, and that is constituted of a protective sheet 52 which presses the work W against the pad 20 and is made of an elastic material, and retainers 28 and 50 which hold the periphery of the protective sheet 52 and, at the same time, are brought into contact with the pad 20, and also a carrier 24 which presses the part of the protective sheet 52 corresponding to the area of the work W against the work W, and has, on the whole circumference of the inner peripheral side of the contact surfaces of the retainers 28 and 50 with the pad 20, annular members 29 having larger wear rates than the retainers 28 and 50 disposed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a work holding head and a polishing apparatus having the work holding head, and in particular, a work holding head suitable for polishing a wafer or the like by a chemical mechanical polishing (CMP) method and the work holding head. The present invention relates to a polishing apparatus having
[0002]
[Prior art]
Conventionally, as shown in FIG. 5, this type of wafer polishing apparatus mainly includes a wafer holding head 3 having a carrier 1 and a retainer ring 2 and a surface plate 5 to which a polishing pad 4 is attached. The wafer 6 is pressed by the carrier 1 against the rotating polishing pad 4 and polished, and the retainer ring 2 arranged on the outer periphery of the carrier 1 is pressed against the polishing pad 4 to surround the periphery of the wafer 6. The inside wafer 6 is prevented from jumping out of the carrier 1 (see Patent Document 1).
[0003]
As the polishing pad 4, a hard one or a soft one is selected and used according to the material (for example, SiO ₂ ) of the polishing layer (insulating film) of the wafer, but when the soft polishing pad 4 is used. In other words, a so-called undulation phenomenon occurs in the polishing pad 4 in that the polishing pad 4 locally swells along the periphery of the portion in contact with the retainer ring 2. When such a phenomenon occurs in the polishing pad 4, the outer peripheral portion 6 </ b> A of the wafer 6 is excessively polished by the raised portion 4 </ b> C of the polishing pad 4, and the polishing uniformity of the wafer 6 is hindered.
[0004]
The swelled portions due to the undulation phenomenon are portions 4A and 4B corresponding to the outer peripheral edge 2A and the inner peripheral edge 2B of the retainer ring 2 located on the upstream side in the rotational direction of the polishing pad 4, and the retainer located on the downstream side in the rotational direction of the polishing pad 4. It occurs in the portion 4C corresponding to the inner peripheral edge 2C of the ring 2. Here, the raised portions 4A and 4B generated in the former are generated at positions away from the outer peripheral portion 6A of the wafer 6, so that there is no problem in polishing. However, the raised portions 4C generated in the latter include the outer peripheral portion of the wafer 6. Since 6A contacts, the outer peripheral edge 6A of the wafer 6 is excessively polished here.
[0005]
For this reason, the above-described wafer polishing apparatus (see Patent Document 1) sets the abutting force of the retainer ring 2 to the polishing pad 4 to a weak appropriate value, thereby preventing the occurrence of the undulation phenomenon and excessive wafer peripheral edge 6A. Although polishing is prevented, the wavy phenomenon cannot be completely eliminated, and the expected effect cannot be obtained.
[0006]
In order to solve such a problem, a proposal by the present applicant has been made (see Patent Document 2), and a predetermined effect has been confirmed. FIG. 6 is a schematic diagram for explaining this principle. That is, a groove 129 </ b> A for allowing the raised portion of the polishing pad 116 to escape is formed on the contact surface 129 of the retainer ring 128 with the polishing pad 116.
[0007]
The groove 129 </ b> A is formed in an annular shape inside the contact surface 129 that actually contacts the polishing pad 116. Further, the height h of the groove 129A is thinner (lower) than the thickness of the wafer 150 so that the upper surface 129B of the groove 129A does not contact the polishing pad 116 and the wafer 150 being polished does not enter the groove 129A. ) Is formed.
[0008]
Further, the width s of the groove 129A is formed such that the raised portion 116C generated due to the inner peripheral edge 128C of the retainer ring 128 located on the downstream side in the rotation direction of the polishing pad 116 can sufficiently enter and escape. ing. As a result, the raised portion 116 </ b> C is generated at a position away from the outer peripheral edge 150 </ b> A of the wafer 150.
[0009]
The raised portions due to the undulation phenomenon also occur in the portions 116A and 116B corresponding to the outer peripheral edge 128A and the inner peripheral edge 128B of the retainer ring 128 located on the upstream side in the rotation direction of the polishing pad 116, but the raised portions 116A and 116B. Occurs at a position away from the outer peripheral portion 150 </ b> A of the wafer 150, and does not adversely affect the uniform polishing of the wafer 150.
[0010]
[Patent Document 1]
Japanese Patent Laid-Open No. 8-229808
[Patent Document 2]
Japanese Patent Laid-Open No. 2002-18709
[Problems to be solved by the invention]
However, even with the proposed polishing apparatus (see Patent Document 2), the wear rate of the retainer ring 128 is fast, and the height h of the groove 129A becomes almost zero when about 100 wafers 150 are processed. The effect of improvement is lost. In addition, if the retainer ring 128 is replaced with an appropriate one for the groove 129A each time, the downtime of the apparatus becomes long, and the operating rate is lowered, which is uneconomical.
[0013]
The present invention has been made in view of such circumstances, and a work holding head capable of uniformly polishing the entire surface of a wafer over a long period of time by preventing excessive polishing of the outer peripheral edge of the wafer, and the work holding An object of the present invention is to provide a polishing apparatus having a head.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a carrier that holds a workpiece and presses the surface of the workpiece against a polishing pad, and is disposed on the outer periphery of the carrier so as to surround the workpiece and to contact the polishing pad. A work piece comprising: a retainer that is in contact; and a ring-shaped member that is disposed on an entire inner circumference of a contact surface of the retainer with the polishing pad and has a higher wear rate than the retainer. A holding head is provided.
[0015]
The present invention also provides a protective sheet made of an elastic material that presses the workpiece against the polishing pad, a retainer that holds the periphery of the protective sheet and abuts against the polishing pad, and a protective sheet that corresponds to the region of the workpiece A carrier that presses the workpiece toward the workpiece, and a ring-shaped member that is disposed on the entire inner periphery of the contact surface of the retainer with the polishing pad and has a higher wear rate than the retainer. A workpiece holding head is provided.
[0016]
According to the present invention, the ring-shaped member whose wear speed is higher than that of the retainer is arranged on the entire circumference on the inner peripheral side of the contact surface of the retainer with the polishing pad. By adopting such a configuration, the ring-shaped member is worn more than the retainer, and a groove (step) having an appropriate depth is formed on the inner peripheral side of the contact surface of the retainer with the polishing pad. As a result, it is possible to prevent excessive polishing of the outer peripheral edge of the wafer and to obtain an effect that the entire surface of the wafer can be uniformly polished over a long period of time.
[0017]
In the present invention, it is preferable that the retainer is made of polyimide, PEEK or PPS, and the ring-shaped member is made of PEEK, PPS or PVC. It is because the effect of the present invention can be more effectively exhibited by using a retainer and a ring-shaped member by such a combination of materials.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a workpiece holding head and a polishing apparatus having the workpiece holding head according to the present invention will be described in detail with reference to the accompanying drawings.
[0019]
FIG. 1 is a perspective view showing an overall configuration of a wafer polishing apparatus 10 that is a polishing apparatus. As shown in the figure, the wafer polishing apparatus 10 is mainly composed of a polishing surface plate 12 and a work holding head (wafer work holding head) 14.
[0020]
The polishing surface plate 12 is formed in a disk shape, and a rotating shaft 16 is connected to the center of the lower surface thereof. The polishing surface plate 12 rotates by driving a motor 18 connected to the rotating shaft 16. A polishing pad 20 is attached to the upper surface of the polishing surface plate 12, and a mechanochemical abrasive is supplied onto the polishing pad 20 from a nozzle (not shown).
[0021]
As shown in FIG. 2, the wafer work holding head 14 which is a work holding head mainly includes a head main body 22, a carrier 24, a carrier pressing means 26, a retainer ring 28, a retainer ring pressing means 30, a protective sheet 52, an air control means. Etc.
[0022]
The head body 22 is formed in a disk shape, and a rotary shaft 32 is connected to the center of the upper surface thereof. The head main body 22 rotates by being driven by a motor (not shown) connected to the rotary shaft 32.
[0023]
The carrier 24 is formed in a disc shape and is arranged at the lower center of the head body 22. A cylindrical recess 34 is formed at the center of the upper surface of the carrier 24. A shaft portion 36 of the head body 22 is fitted into the recess 34 via a pin 38. The rotation is transmitted to the carrier 24 from the head main body 22 through the pin 38.
[0024]
Further, a carrier pressing member 40 is provided on the peripheral edge of the upper surface of the carrier 24. A pressing force is transmitted to the carrier 24 from the carrier pressing means 26 via the carrier pressing member 40.
[0025]
An air suction / blowout groove 42, which is an air supply path for injecting air to the protective sheet 52, is formed on the lower surface of the carrier 24. An air flow path 44 formed inside the carrier 24 is communicated with the suction / blowout groove 42. An intake pump and an air supply pump are connected to the air flow path 44 via an air pipe (not shown). The suction and blowing of air from the suction / blowing groove 42 is performed by switching between the intake pump and the air supply pump.
[0026]
The air suction / blowout groove 42, the air flow path 44, the air piping, the intake pump, the air supply pump, the switching means between the intake pump and the air supply pump, and the like constitute an air control means.
[0027]
The carrier pressing means 26 is disposed on the outer peripheral portion of the lower surface of the head body 22, and applies a pressing force to the carrier pressing member 40 to transmit the pressing force to the carrier 24 coupled thereto. The carrier pressing means 26 is preferably composed of a rubber sheet airbag 46 that expands and contracts by air intake and exhaust. An air supply mechanism 48 for supplying air is connected to the airbag 46, and the air supply mechanism 48 is provided with a regulator (not shown) that adjusts the pressure of air pumped from a pump (not shown).
[0028]
The retainer includes a holder (retainer ring holder) 50 and a retainer ring 28 which are retainer bodies. The retainer ring 28 is formed in a ring shape and is disposed on the outer periphery of the carrier 24. The retainer ring 28 is attached to a retainer ring holder 50 provided on the wafer work holding head 14, and a protective sheet 52 is stretched around the inner periphery thereof.
[0029]
A retainer ring holder 50 as a retainer body is formed in a ring shape, and an annular recess 54 is formed on the lower surface thereof as shown in FIGS. On the other hand, a convex portion 56 that fits into the concave portion 54 is formed on the upper surface of the retainer ring 28. By fitting the convex portion 56 into the concave portion 54 of the retainer ring holder 50, the retainer ring 28 is retained by the retainer ring 28. Attached to the ring holder 50.
[0030]
A step 28A is formed on the lower surface of the retainer ring 28, that is, the entire circumference on the inner peripheral side of the contact surface with the polishing pad 20, and a ring-shaped member 29 having a higher wear speed than the retainer ring 28 fills the step 28A. It is mated. The ring-shaped member 29 shown in FIG. 3 is fitted so as to fill the step 28A of the retainer ring 28, and the lower surface of the ring-shaped member 29 and the lower surface of the retainer ring 28 are in an initial state that is flush with each other. 2 shows a state after a predetermined number of wafers W have been polished.
[0031]
In this state, the ring-shaped member 29 is worn more than the retainer ring 28, and a groove (step) having an appropriate depth Δh is formed on the inner peripheral side of the contact surface of the retainer ring 28 with the polishing pad. Yes.
[0032]
As a method for fixing the ring-shaped member 29 to the step 28A of the retainer ring 28, various known means such as various adhesives and double-sided pressure-sensitive adhesive tapes can be employed.
[0033]
As the material of the retainer ring holder 50, various metal materials can be used. In particular, stainless steel, anodized aluminum, and the like can be preferably used from the viewpoints of corrosion resistance to an abrasive and rust prevention effect.
[0034]
The material of the retainer ring 28 is preferably a material that has a predetermined or higher wear resistance when it is worn by the polishing pad 20 and that does not cause a problem even if mixed with an abrasive, such as PET, polyethylene, Polypropylene, PFA, PTFE, PPS, PEEK, polyimide (trade name: Vespel) and the like can be used. Of these, PEEK can be preferably used.
[0035]
As a material of the ring-shaped member 29, PEEK, PPS, PVC or the like can be used. Of these, PPS can be preferably used. The wear rate of the ring-shaped member 29 by the polishing pad 20 is required to be higher than the wear rate of the retainer ring 28 by the polishing pad 20. Otherwise, a groove (step) having an appropriate depth Δh cannot be formed in the retainer ring 28 due to wear of the lower surface of the ring-shaped member 29.
[0036]
The protective sheet 52 is formed in a circular shape and has a plurality of holes 52A. The protective sheet 52 is stretched inside the retainer ring 28 by sandwiching the peripheral edge portion between the retainer ring 28 and the retainer ring holder 50. That is, the protective sheet 52 is formed in a thin disk shape, and when the retainer ring 28 is attached, the peripheral portion thereof is sandwiched between the convex portion 56 of the retainer ring 28 and the concave portion 54 of the retainer ring holder 50. It is stretched inside the retainer ring 28. By stretching in this way, the protective sheet 52 is pulled in the outer circumferential direction at the same time as being attached, and is stretched uniformly over the entire surface.
[0037]
The protective sheet 52 has a plurality of holes (not shown) through which bolts 58, 58,.
[0038]
The air ejected by the suction / blowing groove 42 of the carrier 24 forms an air layer between the carrier 24 and the protective sheet 52 by the pressing force applied by the carrier pressing means 26, and the principle of a so-called hydrostatic bearing ( The wafer W is pressed against the polishing pad 20 through the protective sheet 52 by the principle of the air bearing.
[0039]
The protective sheet 52 is an elastic member that is flexible enough to transmit the air dynamic pressure distribution formed by the air layer formed by the suction / blowout grooves 42 of the carrier 24 to the wafer W, and damages the wafer W. Therefore, it is required that the material does not contaminate.
[0040]
Further, when the retainer ring 28 is worn, it is necessary to have flexibility that can change the amount of deflection following the retainer ring 28 and sufficient strength against contact and friction with the wafer W during polishing.
[0041]
When the strength of the protective sheet 52 is insufficient, the protective sheet 52 is damaged or wrinkles occur in the protective sheet 52, and normal polishing work becomes difficult. On the other hand, if the strength of the protective sheet 52 is too high, the flexibility is insufficient, and the retainer ring 28 cannot be followed when worn. As a result, the replacement frequency of the retainer ring 28 increases.
[0042]
There are two types of wafers W, a notch type and an orientation flat type. In the case of the orientation flat type, the hardness of the protective sheet 52 is preferably high in order to reduce the influence of the orientation flat portion.
[0043]
On the other hand, in the case of the notch type, the hardness of the protective sheet 52 is preferably low as long as it has sufficient strength to withstand friction with the wafer W during polishing. That is, if the protection sheet 52 is highly flexible, the attachment position of the protection sheet 52 to the retainer ring 28 can be sufficiently higher than the upper surface of the wafer W. Thereby, even if the wear amount of the retainer ring 28 is large, the retainer ring 28 can be used, and the replacement frequency of the retainer ring 28 can be reduced.
[0044]
The thickness of the protective sheet 52 is preferably 0.1 to 2 mm. If the thickness of the protective sheet 52 exceeds 2 mm, the radius of curvature of the protective sheet 52 increases in the vicinity of the outer peripheral portion of the wafer W, and the outer peripheral portion of the wafer W cannot be polished with an appropriate pressing force, making normal polishing work difficult. It becomes.
[0045]
On the other hand, if the thickness of the protective sheet 52 is less than 0.1 mm, the hardness of the protective sheet 52 must be increased in order to maintain the strength of the protective sheet 52, and as a result, the back surface of the wafer W is damaged. The possibility increases and the function as a protective sheet cannot be exhibited.
[0046]
As a material of the protective sheet 52, chloroprene rubber, nitrile rubber, etc. are used as rubber materials, and PET, polyethylene, polypropylene, PFA, PTFE, etc. are polyimide resins as resin materials such as tetrafluoroethylene resin. As a resin material such as PEEK, Vespel (trade name) or the like can be used.
[0047]
The retainer ring 28 is fixed to the retainer ring holder 50 by fitting the convex portion 56 into the concave portion 54 of the retainer ring holder 50 and then screwing it with bolts 58, 58. Therefore, screw holes 60, 60,... Are formed in the retainer ring 28 at regular intervals, and through holes 62, 62,... Are formed in the retainer ring holder 50 at regular intervals.
[0048]
Further, the convex portion 56 formed on the retainer ring 28 and the concave portion 54 formed on the retainer ring holder 50 have inner circumferential wall surfaces 54A and 56A formed in a tapered shape (having a tapered portion). Thus, the fitting operation can be easily performed.
[0049]
As shown in FIG. 2, an air layer is formed between the carrier 24 and the protective sheet 52 under the carrier 24 on which the protective sheet 52 is stretched. The wafer W is pressed against the carrier 24 through the air reservoir 74. The air reservoir 74 is increased in internal pressure by blowing air from the suction / blowing groove 42 of the carrier 24. The holes 52A formed in the protective sheet 52 act as suction holes when the wafer W is held and transported, and act as air ejection holes during polishing.
[0050]
The retainer ring holder 50 is attached to an attachment member 64 formed in a ring shape via a snap ring 66. The snap ring 66 is formed in a ring shape, and a groove 66A is formed on the inner periphery thereof as shown in FIG. The snap ring 66 is cut and formed so that it can be expanded and contracted. The retainer ring holder 50 and the mounting member 64 are integrated with each other by fitting the outer peripheral flange portions 50A and 64A formed on the outer periphery of the upper end portion and the outer periphery of the lower end portion into the groove 66A formed in the snap ring 66. Fixed.
[0051]
An inner peripheral flange portion 50B is formed on the inner peripheral portion of the retainer ring holder 50, and a flange portion 24A formed on the outer peripheral portion of the carrier 24 is loosely inserted into the inner peripheral flange portion 50B. Thereby, an air layer is formed between the carrier 24 and the protective sheet 52.
[0052]
The retainer ring pressing member 68 of FIG. 2 is connected to the mounting member 64. The retainer ring 28 is transmitted with a pressing force from the retainer ring pressing means 30 via the retainer ring pressing member 68.
[0053]
The retainer ring pressing means 30 is disposed on the peripheral edge of the central portion of the lower surface of the head body 22, and applies a pressing force to the retainer ring pressing member 68 to press the retainer ring 28 coupled thereto against the polishing pad 20. The retainer ring pressing means 30 is also preferably formed of a rubber sheet airbag 70 in the same manner as the carrier pressing means 26. An air supply mechanism 72 for supplying air is connected to the airbag 70, and the air supply mechanism 72 is provided with a regulator (not shown) that adjusts the pressure of air pumped from a pump (not shown).
[0054]
Next, the action of the groove (step) having a depth Δh formed in the retainer ring 28 when the lower surface of the ring-shaped member 29 shown in FIG. 3 is worn will be described with reference to FIG. The groove 29A having a depth Δh is formed in an annular shape inside the contact surface that actually contacts the polishing pad 20. The step Δh of the groove 29A is thinner (lower) than the thickness of the wafer W so that the upper surface 29B of the groove 29A does not contact the polishing pad 20 and the wafer W being polished does not enter the groove 29A. Is formed.
[0055]
Furthermore, the width S of the groove 29A is formed such that the raised portion 20C generated due to the inner peripheral edge 28C of the retainer ring 28 located on the downstream side in the rotation direction of the polishing pad 20 can sufficiently enter and escape. ing. As a result, the raised portion 20 </ b> C is generated at a position away from the outer peripheral edge WA of the wafer W.
[0056]
Note that the swelled portion due to the undulation phenomenon also occurs in the portions 20D and 20E corresponding to the outer peripheral edge 28D of the retainer ring 28 and the inner peripheral edge 28E of the step 28A located on the upstream side in the rotational direction of the polishing pad 20. Since 20D and 20E are generated at positions away from the outer peripheral portion WA of the wafer W, they do not adversely affect the uniform polishing of the wafer W.
[0057]
The wafer polishing method of the wafer polishing apparatus 10 configured as described above is as follows.
[0058]
First, the wafer W is held by the wafer work holding head 14 and placed on the polishing pad 20. At this time, the wafer W is sucked and held by using the sucking / blowing grooves 42 formed on the lower surface of the carrier 24. For this suction, the protective sheet 52 has a plurality of holes 52A (see FIG. 3). The wafer W is sucked and held through the hole 52A.
[0059]
Next, air is supplied to the airbags 46 and 70 from a pump (not shown). At the same time, air is blown out from the suction / blowing groove 42 of the carrier 24. As a result, the internal pressure of the air reservoir 74 is increased and the airbags 46 and 70 are inflated, and the wafer W and the retainer ring 28 are pressed against the polishing pad 20 with a predetermined pressure. In this state, the polishing surface plate 12 is rotated in the direction A in FIG. 1, and the wafer work holding head 14 is rotated in the direction B in FIG. Then, slurry is supplied onto the rotating polishing pad 20 from a nozzle (not shown). Thereby, the lower surface of the wafer W is polished by the polishing pad 20.
[0060]
Since the protective sheet 52 has a plurality of holes 52A (see FIG. 3), the air supplied to the air reservoir 74 presses the back surface of the wafer W through the protective sheet 52 from the holes 52A. To do. No direct pressing force acts between the protective sheet 52 present in the air layer and the back surface of the wafer W. Therefore, the thickness unevenness of the protective sheet 52 does not affect the processing accuracy of the wafer W.
[0061]
In addition, since the protective sheet 52 has a plurality of holes 52A for suction, a thin air layer is formed between the protective sheet 52 and the back surface of the wafer W. There is almost no air flow, and even if there is an air flow, the amount of air is so small that the slurry does not aggregate.
[0062]
As mentioned above, although the example of embodiment of the workpiece | work holding head which concerns on this invention, and the grinding | polishing apparatus which has this work holding head was demonstrated, this invention is not limited to the example of the said embodiment, Various aspects can be taken. .
[0063]
For example, in the example of the embodiment, the carrier 24 is arranged above the protective sheet 52 and the wafer W is pressed using air pressure. However, the carrier 24 is physically brought into contact with the protective sheet 52. It can also be configured to press the wafer W.
[0064]
Further, in the present embodiment, a step 28A is formed on the entire inner circumference side of the contact surface of the retainer ring 28 with the polishing pad 20, and the ring-shaped member 29 having a higher wear rate than the retainer ring 28 has a step. Although the configuration of fitting so as to fill in 28 </ b> A is adopted, it may be configured by integral molding or the like of the retainer ring 28 and the ring-shaped member 29 instead of this.
[0065]
In short, if the ring-shaped member 29 whose wear speed is higher than that of the retainer ring 28 is arranged on the entire inner circumference side of the contact surface of the retainer ring 28 with the polishing pad 20, the effect of the present invention can be obtained. can get.
[0066]
In the present embodiment, the wafer work holding head 14 has the head body 22, the carrier 24, the carrier pressing means 26, the retainer ring 28, the retainer ring pressing means 30, the protective sheet 52, and the like. The head includes a carrier that holds the workpiece and presses the surface of the workpiece against the polishing pad 20, and a retainer that is disposed on the outer periphery of the carrier and surrounds the periphery of the workpiece and is in contact with the polishing pad 20. You can also
[0067]
Further, in the present embodiment, the retainer ring 28 and the retainer ring holder 50 sandwiching the protective sheet 52 are fixed by the bolts 58, but they may be fixed by bonding with an adhesive.
[0068]
【The invention's effect】
As described above, according to the present invention, a step is formed in the entire circumference on the inner peripheral side of the contact surface of the retainer with the polishing pad, and the ring-shaped member having a higher wear rate than the retainer fills this step. Are fitted. By adopting such a configuration, the ring-shaped member is worn more than the retainer, and a groove (step) having an appropriate depth is formed on the inner peripheral side of the contact surface of the retainer with the polishing pad. As a result, it is possible to prevent excessive polishing of the outer peripheral edge of the wafer and to obtain an effect that the entire surface of the wafer can be uniformly polished over a long period of time.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the overall structure of a wafer polishing apparatus. FIG. 2 is a longitudinal sectional view showing the configuration of a wafer work holding head. FIG. 3 is a cross-sectional view of the main part showing the configuration of a retainer ring. FIG. 5 is a schematic diagram for explaining a profile of a polishing pad in conventional wafer polishing. FIG. 6 is a schematic diagram for explaining a profile of a polishing pad in conventional wafer polishing. Schematic diagram [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Wafer polisher, 12 ... Polishing surface plate, 14 ... Wafer work holding head, 20 ... Polishing pad, 24 ... Carrier, 28 ... Retainer ring, 29 ... Ring-shaped member, 42 ... Suction / outlet groove, 44 ... Air flow Road, 46 ... Air bag, 48 ... Air supply mechanism, 50 ... Retainer ring holder, 52 ... Protection sheet, 72 ... Air supply mechanism, 74 ... Air reservoir, W ... Wafer

Claims (4)

A carrier that holds the workpiece and presses the surface of the workpiece against the polishing pad;
A retainer which is disposed on the outer periphery of the carrier and surrounds the periphery of the workpiece and is in contact with the polishing pad;
A ring-shaped member that is disposed on the entire circumference on the inner circumferential side of the contact surface of the retainer with the polishing pad, and has a wear rate greater than that of the retainer;
A work holding head comprising: A protective sheet made of an elastic material that presses the workpiece against the polishing pad;
A retainer that holds the periphery of the protective sheet and is in contact with the polishing pad;
A carrier that presses the protective sheet corresponding to the area of the workpiece toward the workpiece;
A ring-shaped member that is disposed on the entire circumference on the inner peripheral side of the contact surface of the retainer with the polishing pad, and has a wear rate greater than that of the retainer;
A work holding head comprising: The work holding head according to claim 1 or 2, wherein the retainer is formed of polyimide, PEEK, or PPS, and the ring-shaped member is formed of PEEK, PPS, or PVC. A polishing apparatus comprising the work holding head according to claim 1.

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