JP3725275B2 - Wafer polishing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wafer polishing apparatus, and more particularly to an improvement for improving the polishing amount uniformity on a wafer surface.
[0002]
[Prior art]
Recently, in the manufacturing process of a semiconductor device, a circuit pattern is formed by vapor-depositing aluminum or the like on the mirror surface of a wafer, and SiO 2 is formed thereon. ₂ A technique is often used in which, after forming an insulating film, etc., the insulating film is flattened by polishing, and the internal structure of the element is sequentially constructed thereon.
[0003]
As a wafer polishing apparatus for polishing the laminated insulating film, a disk-shaped platen having a polishing pad affixed to the surface, and a plurality of wafers that hold one surface of the wafer to be polished and abut the other surface of the wafer against the polishing pad And a wafer driving head for rotating these wafer holding heads relative to the platen and performing polishing by supplying a slurry containing abrasive grains between the polishing pad and the wafer is widely known. It has been.
[0004]
As this type of wafer polishing apparatus, what is called a template type having a simple configuration is still widely used. The wafer holding head of this apparatus has a horizontal disk-shaped carrier having an outer diameter larger than that of the wafer, and an annular and thin template surrounding the outer periphery of the wafer is fixed to the lower surface of the carrier. Polishing is performed by rubbing the lower surface of the wafer against the polishing pad on the platen while hooking the outer periphery of the wafer. In this case, the lower surface of the template is generally configured not to contact the polishing pad.
[0005]
In the template type wafer polishing apparatus, since the polishing is performed while pressing the wafer against the polishing pad with a constant pressure, the wafer slightly sinks into the polishing pad. Therefore, the contact pressure with the polishing pad is inevitably larger at the outer peripheral portion of the wafer than at the central portion of the wafer, and the polishing amount at the outer peripheral portion of the wafer is larger than the polishing amount at the central portion. There was a problem that it was difficult to make uniform.
[0006]
On the other hand, US Pat. No. 5,205,082 discloses a wafer holding head as shown in FIG. This wafer holding head has a hollow head main body 1, a diaphragm 2 horizontally stretched in the head main body 1, and a carrier 4 fixed to the lower surface of the diaphragm 2, and air defined by the diaphragm 2. By supplying pressurized air from the pressurized air source 10 to the chamber 6 through the shaft 8, the carrier 4 has a floating head structure that can press the carrier 4 downward.
Such a floating head structure has an advantage that the contact pressure of the wafer with respect to the polishing pad can be made uniform.
[0007]
A retainer ring 12 is concentrically disposed on the outer periphery of the carrier 4, and the retainer ring 12 is also fixed to the diaphragm 2. The lower end of the retainer ring 12 protrudes below the carrier 4, thereby holding the outer periphery of the wafer attached to the lower surface of the carrier 4. By holding the outer periphery of the wafer in this way, it is possible to prevent a problem that the wafer being polished is detached from the carrier 4.
Furthermore, the wafer is surrounded by a retainer ring 12, and the lower end of the retainer ring 12 is polished at the same height as the lower surface of the wafer, so that overpolishing at the outer peripheral portion of the wafer can be prevented.
[0008]
Incidentally, the polishing pad is required to have both uniformity and flatness of polishing on the wafer surface.
However, in the case of a soft polishing pad, it is excellent in uniformity because pressure is easily applied to the entire wafer surface due to its elasticity, but the polishing amount close to the convex portion is also in the concave portion of the wafer surface. Therefore, it has a characteristic inferior in flatness. On the contrary, in the case of a hard polishing pad, it is easy to apply a strong pressure to the convex part compared to the concave part on the wafer surface, so it is excellent in flatness of polishing, but the pressure is uniform over the entire wafer surface. Is difficult to obtain, and has the characteristics of poor uniformity of polishing.
[0009]
As a countermeasure against this, a two-layer polishing pad in which a hard surface layer is provided on an elastic support layer, which is a soft polishing pad, has been proposed. That is, this polishing pad has both characteristics of uniformity by the elastic support layer and flatness by the hard surface layer, and achieves both uniformity and flatness required for wafer polishing.
[0010]
[Problems to be solved by the invention]
However, the following problems remain in the above wafer polishing apparatus.
That is, as a result of detailed examinations of the wafer polishing apparatus by the present inventors, depending on the material of the polishing pad and the contact pressure of the retainer ring 12, as shown in FIG. The polishing pad P swells locally along the periphery (hereinafter referred to as “waving deformation” for convenience), and the peripheral part G of the wafer W is excessively polished by the swelled part T, so that the polishing uniformity of the wafer W is improved. A new phenomenon has been discovered that it is inhibited.
That is, the problem of overpolishing the wafer outer peripheral portion has not been completely solved.
In particular, in the above-described two-layer polishing pad, due to the elastic effect of the soft polishing pad provided in the lower layer, the reaction against the contact pressure of the retainer ring is large, and the occurrence of the wavy deformation tends to be remarkable. was there.
[0011]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a wafer polishing apparatus that prevents overpolishing at the outer peripheral portion of the wafer and improves the polishing amount uniformity.
[0012]
[Means for Solving the Problems]
The present invention employs the following configuration in order to solve the above problems. That is, in the wafer polishing apparatus according to claim 1, the platen having the polishing pad affixed to the surface, and one or more of the one surface of the wafer to be polished and holding the other surface of the wafer in contact with the polishing pad A wafer holding head; and a head driving mechanism for polishing the other surface of the wafer with the polishing pad by driving the wafer holding head, the wafer holding head holding the one surface of the wafer to be polished. And a retainer ring disposed concentrically on the outer periphery of the carrier. The retainer ring is displaceable in the head axis direction, and its lower surface contacts the polishing pad during polishing. The bottom surface of the retainer ring has a raised pad of a polishing pad that occurs near the inside of the retainer ring during polishing. Groove to release the part is The inner ring is formed over the entire circumference, and the lower surface of the retainer ring is divided by the groove into an outer pressing surface and an inner pressing surface having a smaller area than the outer pressing surface, A technique is adopted in which the width of the groove is set in a range of 0.5% to 1.0% with respect to the diameter of the wafer.
[0013]
In this wafer polisher, the entire circumference of the lower surface of the retainer ring Toward the inner circumference Since the groove is formed, the raised portion of the polishing pad generated in the vicinity of the inside due to the contact pressure of the retainer ring at the time of polishing is partially guided to the groove and escaped radially outward. The raised part becomes smaller. That is, the wavy deformation of the polishing pad is suppressed, and overpolishing of the wafer outer peripheral portion is mitigated. On the other hand, if the width of the groove is too large, the contact area between the retainer ring and the pad becomes narrow, the actual pressure increases, the amount of pad deformation increases, and if it is too small, there is no effect. Therefore, it is preferably set in a range of 0.5% to 1.0% with respect to the diameter of the wafer W.
[0015]
In addition, since the groove is formed on the entire lower surface of the retainer ring, The bulging portion generated by the contact pressure of the retainer ring is dispersed when a part thereof bulges in the groove portion, and the bulging portion generated in the vicinity of the inner side of the retainer ring is reduced to suppress undulation deformation. Furthermore, since the groove portion is arranged near the inner periphery of the lower surface, and the lower surface of the retainer ring is divided into the outer pressing surface and the inner pressing surface by the groove portion, the area of the inner pressing surface that greatly affects the inner wavy deformation Is less than the outer pressing surface. That is, since the contact pressure applied to the vicinity of the inner side of the retainer ring is reduced, the raised portion generated by the reaction is also reduced.
[0016]
Claim 2 In a wafer polishing apparatus, a platen having a polishing pad affixed to the surface, one or more wafer holding heads that hold one surface of the wafer to be polished and bring the other surface of the wafer into contact with the polishing pad, and these wafers A head driving mechanism that polishes the other surface of the wafer with the polishing pad by driving a holding head, and the wafer holding head includes a disk-shaped carrier for holding the one surface of the wafer to be polished; A retainer ring disposed concentrically on the outer periphery of the carrier, the retainer ring being displaceable in the head axis direction, and configured such that its lower surface abuts on the polishing pad during polishing, On the lower surface of the retainer ring, there is a step on the entire circumference that escapes the raised part of the polishing pad that occurs near the inside of the retainer ring during polishing. Formed me, it stepped portion, a technique wherein it is set than the thickness to a small level difference of at least the wafer disposed on the inner peripheral side of the lower surface of the retainer ring is employed.
In this wafer polishing apparatus, since the escape portion is a step portion disposed on the inner peripheral side, a raised portion is generated in the step portion due to the contact pressure of the retainer ring. That is, since the raised portion escapes radially outward from the outer peripheral portion of the wafer, the top portion is separated from the outer peripheral portion of the wafer, and the influence of the raised portion on polishing is suppressed. Furthermore, since the step portion is set to a step smaller than the thickness of the wafer, even if the wafer is displaced in the horizontal direction during polishing, the penetration of the wafer outer peripheral portion under the step portion is suppressed.
[0017]
Claim 3 In wafer polishing equipment, Claim 2 In this wafer polishing apparatus, a technique is adopted in which the width of the stepped portion is set in a range of 1.0% to 2.5% with respect to the diameter of the wafer.
If the width of the step portion is 8 ″ φ, the width of the raised portion is 2 mm or more, so 1.0% or more is necessary, and if it is too large, the amount of pad deformation increases due to an increase in actual pressure. Preferably, it is set within a range of 1.0% to 2.5% with respect to the diameter of the wafer.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
A wafer polishing apparatus according to a first embodiment of the present invention will be described below with reference to FIGS.
[0019]
First, the entire configuration will be briefly described with reference to FIG. 1. In the figure, reference numeral 21 denotes a base, and a disk-shaped platen 22 is horizontally installed at the center of the base 21. The platen 22 is rotated about its axis by a platen drive mechanism provided in the base 21, and a polishing pad 24 is stuck on the entire upper surface thereof.
[0020]
An upper mounting plate 28 is horizontally fixed above the platen 22 via a plurality of support columns 26. A disk-shaped carousel (head drive mechanism) 30 is fixed to the lower surface of the upper mounting plate 28, and a total of six wafer holding heads 32 facing the platen 22 are provided on the carousel 30.
As shown in FIG. 2, these wafer holding heads 32 are arranged every 60 ° around the central axis at the same distance from the center of the carousel 30, and are each planetarily rotated by the carousel 30. However, the number of wafer holding heads 32 is not limited to six, and may be 1 to 5 or 7 or more.
[0021]
Next, the wafer holding head 32 will be described with reference to FIG.
As shown in FIG. 3, the wafer holding head 32 is fixed to the lower surface of the diaphragm 44, a hollow head body 34 that is disposed perpendicular to the axis and has an open lower end, a diaphragm 44 that is stretched inside the head body 34, and the bottom surface of the diaphragm 44. The disc-shaped carrier 46 and an annular retainer ring 50 arranged concentrically on the outer periphery of the carrier 46 are provided.
[0022]
The head body 34 includes a disk-shaped top plate portion 36 and a cylindrical peripheral wall portion 38 fixed to the outer periphery of the top plate portion 36, and the top plate portion 36 is coaxially fixed to the shaft 42 of the carousel 30. Has been.
An annular support portion 40 that protrudes radially inward over the entire circumference is formed at the lower end of the peripheral wall portion 38. A horizontal step portion 38 </ b> A is formed on the inner peripheral wall of the peripheral wall portion 38, and the outer peripheral portion of the disk-shaped diaphragm 44 is placed on the inner peripheral wall and fixed by a fixing ring 45.
The diaphragm 44 is formed of an elastic material such as various rubbers.
[0023]
The carrier 46 is formed of a material having high rigidity such as ceramic and has a constant thickness and does not elastically deform. The carrier 46 is fixed with a plurality of bolts to a fixing ring 48 arranged coaxially on the upper surface of the diaphragm 44.
A flange portion 48A is formed at the upper end of the fixing ring 48 so as to spread outward over the entire circumference. When the head is raised, the flange portion 48A is supported by a support member (not shown) provided on the top plate portion 36. The weight of the carrier 46 is supported by being supported.
[0024]
When polishing is performed, the wafer W is sucked and fixed by a suction hole 46 a formed on the lower surface of the carrier 46 connected to a suction means (not shown) such as a vacuum pump.
Further, the wafer W is attached to the lower surface of the carrier 46 via a circular wafer adhering sheet S.
The wafer adhering sheet S is formed of, for example, a water-absorbing material, and adsorbs the wafer with surface tension when absorbing moisture. Examples of the material of the wafer adhering sheet S include non-woven fabrics, but are not limited thereto.
[0025]
Moreover, although the thickness of the wafer adhesion sheet S is not limited, Preferably it is 0.4-0.8 mm. However, the present invention does not necessarily use the wafer adhering sheet S. For example, the wafer W may be adhered to the wafer adhering surface of the carrier 46 via wax, or other adhering means may be used. Good.
[0026]
The retainer ring 50 has an annular shape in which an upper end surface and a lower end surface are horizontal and flat.
The retainer ring 50 is disposed concentrically with a slight gap between the carrier 46 and the outer peripheral surface of the carrier 46 (in this embodiment, set to about 1.0 mm), and is independent of the carrier 46. Can be displaced vertically.
Further, a support portion 50a protruding outward in the radial direction is formed on the outer peripheral surface of the upper retainer ring 50A, and this support portion 50a is formed at the lower end of the peripheral wall portion 38 when the wafer holding head 32 is pulled up. The support part 40 is supported.
[0027]
While the upper end of the retainer ring 50 is in contact with the lower surface of the diaphragm 44, a fixing ring 58 is disposed concentrically on the diaphragm 44 so as to face the retainer ring 50, and the retainer ring 50 and the fixing ring 58 are formed by a plurality of screws. It is fixed.
[0028]
On the lower surface of the retainer ring 50, FIG. and FIG. As shown in FIG. 2, the rising portion T of the polishing pad 24 generated near the inside of the retainer ring 50 during polishing is released. Groove 70 Is formed over the entire circumference and closer to the inner circumference. Further, the lower surface of the retainer ring 50 is divided into an outer pressing surface 71 and an inner pressing surface 72 having a smaller area than the outer pressing surface 71 by the groove portion 70. The depth of the groove portion 70 is preferably equal to or greater than the height of the raised portion T generated in the groove portion 70, for example, 1 mm or more, but is not limited to this value.
[0029]
The width of the groove 70 is preferably set in a range of 0.5% to 1.0% with respect to the diameter of the wafer W. That is, if this number is too large, the contact area between the retainer ring and the pad becomes narrow and the actual pressure increases, so that the amount of pad deformation increases. If it is too small, there is no effect.
The width of the inner pressing surface 72 is preferably set in a range of 0% to 3% with respect to the diameter of the wafer W. That is, the groove area is increased at the outer periphery of the retainer ring, and the pad deformation amount is increased.
However, depending on the wafer material and polishing conditions, the above ranges may be excluded.
[0030]
A flow path 54 is formed in the shaft 42, and a fluid chamber 52 defined between the head main body 34 and the diaphragm 44 is connected to a pressure adjusting mechanism 56 through the flow path 54. Then, by adjusting the fluid pressure in the fluid chamber 52 by the pressure adjusting mechanism 56, the diaphragm 44 is displaced up and down, and the pressing pressure of the carrier 46 and the retainer ring 50 on the polishing pad 24 changes simultaneously.
In general, it is sufficient to use air as the fluid, but other types of gases and liquids may be used as necessary.
[0031]
In order to perform wafer polishing by the wafer polishing apparatus, first, the wafer W is disposed between the polishing pad 24 and each carrier 46, and the retainer ring 50 is brought into contact with the polishing pad 24 so that the outer periphery of the wafer W is retained by the retainer. It is supported by the ring 50.
Next, the platen 22 is rotated while adjusting the fluid pressure by the pressure adjusting mechanism 56 so that the contact pressure of the wafer W against the polishing pad 24 (pressing pressure by the carrier) becomes a desired value, and the wafer holding head 32 is moved to the platen. The planet is rotated with respect to 22.
[0032]
According to the wafer polishing apparatus as described above, since the groove portion 70 is formed on the entire lower surface of the retainer ring 50, in the case of the conventional retainer ring 12 having no groove portion 70 as shown in FIG. In comparison, as shown in FIG. 7, the bulging portion T generated by the contact pressure of the retainer ring 50 is dispersed as a part T1 escapes into the groove portion 70 and rises, and the bulging portion generated near the inside of the retainer ring. T2 becomes small and the undulating deformation is suppressed.
[0033]
Further, since the groove portion 70 is arranged closer to the inner periphery of the lower surface, and the lower surface of the retainer ring 50 is divided into the outer pressing surface 71 and the inner pressing surface 72 by the groove portion 70, the inner pressing that greatly acts on the inner wavy deformation The area of the surface 72 is smaller than that of the outer pressing surface 71. That is, since the contact pressure applied to the vicinity of the inner side of the retainer ring 50 is reduced, the raised portion generated by the reaction is also reduced. As a result, the wavy deformation of the polishing pad 24 is suppressed, and overpolishing of the outer peripheral portion of the wafer W is mitigated.
[0034]
As the polishing pad 24, instead of the conventionally used one-layer pad, as shown in FIGS. 6 and 7, the above-described two-layer polishing pad, that is, the surface hard layer 24A in contact with the wafer W, And at least two elastic support layers 24B located between the surface hard layer 24A and the platen 22.
Such a laminated polishing pad has a special effect in increasing the wafer polishing accuracy as will be described later, but at the same time, the problem described with reference to FIG. 12 tends to be more prominent than the single-layer polishing pad. Have
[0035]
Therefore, when combined with the present invention, the effects of the two are synergistic and provide particularly good effects in increasing the polishing accuracy of the wafer. However, it goes without saying that the present invention is not limited to such a laminated polishing pad.
Hereinafter, the laminated polishing pad will be specifically described.
[0036]
The shore hardness of the hard surface layer is preferably 80 to 100, more preferably 90 to 100, and the shore hardness of the elastic support layer is preferably 50 to 80, more preferably 60 to 75. The thickness of the hard surface layer is preferably 0.5 to 1.5 mm, more preferably 0.8 to 1.3 mm, and the thickness of the elastic support layer is preferably 0.5 to 1.5 mm, more preferably It is set to 0.8 to 1.3 mm.
[0037]
The surface hard layer 24A and the elastic support layer 24B are each preferably foamed polyurethane or non-woven fabric. In particular, the surface hard layer 24A is preferably foamed polyurethane and the elastic support layer 24B is preferably a non-woven fabric such as polyester.
When the surface hard layer 24A and the elastic support layer 24B are formed of a nonwoven fabric, an impregnating agent such as polyurethane resin may be impregnated. However, the polishing pad 24 may be made of a material other than the above as long as the hardness range is satisfied.
[0038]
When this type of two-layer polishing pad is used, an excellent effect is exhibited particularly in wafer polishing in the insulating film separation technique. In this type of insulating film separation technique, for example, a wiring pattern such as aluminum is deposited on the mirror surface of a wafer to form a circuit pattern, and an insulating film such as SiO2 is laminated thereon by BPSG, PTEOS, or CVD. Thereafter, the insulating film is flattened by polishing, and the internal structure of the element is further formed thereon.
[0039]
In the case of the insulating film polishing, there may be initial unevenness due to a circuit pattern or the like on the wafer surface, but in the laminated polishing pad, the pad surface is composed of a relatively hard surface hard layer 24A. The surface of the polishing pad 24 hardly deforms elastically following the unevenness. Accordingly, it is possible to reduce the occurrence of a step after polishing due to the initial unevenness.
[0040]
Further, since the surface hard layer 24A that directly contacts the wafer W is elastically supported from the back side by the elastic support layer 24B, the effect of equalizing the wafer contact pressure by the wafer holding head 32 that is a floating type head, and Even when the cushioning effect by the elastic support layer 24B is synergistic and the waviness is generated in the polishing pad 24 or the wafer W, the surface hard layer 24A is deformed along the waviness and uniformly contacted over the entire surface of the wafer W. Effect is obtained. As a result, the polishing speed of the wafer W by the polishing pad 24 is made uniform over the entire surface of the wafer, so that the non-uniformity of the wafer thickness after polishing can be reduced, and the level difference that has been difficult to achieve in the past ( Improvements in flatness and thickness uniformity can be achieved simultaneously.
[0041]
Further, in the laminated polishing pad, since the hard surface layer 24A is lined with a soft elastic support layer 24B, when the hard surface layer 24A is strongly suppressed by the retainer ring 50, the periphery of the pressed portion is as shown in FIG. In addition, there is a strong tendency to swell.
However, by elastically deforming the raised portion T in the direction of escaping radially outward from the outer peripheral portion of the wafer W, overpolishing of the outer peripheral portion of the wafer W can be mitigated and the effect of the laminated polishing pad can be fully exhibited. It is. This is common to the following second embodiment.
[0042]
Next, a second embodiment of the wafer polishing apparatus according to the present invention will be described with reference to FIGS.
[0043]
The difference between the second embodiment and the first embodiment is that the groove portion 70 is formed on the lower surface of the retainer ring 50 in the first embodiment. However, as shown in FIGS. The lower surface of the retainer ring 80 in the embodiment is that a step portion (relief portion) 81 that is disposed on the inner peripheral side and is set to a step smaller than the thickness of the wafer W is formed.
[0044]
That is, in the wafer polishing apparatus according to the second embodiment, since the stepped portion 81 disposed on the inner peripheral side is formed on the lower surface of the retainer ring 80, the contact pressure of the retainer ring 80 as shown in FIG. A raised portion T is generated in the step portion 81. That is, since the raised portion T escapes radially outward from the outer peripheral portion of the wafer W, the top portion is separated from the outer peripheral portion of the wafer W, and the influence on the polishing by the raised portion T is suppressed.
[0045]
Furthermore, since the step portion 81 is set to a step smaller than the thickness of the wafer W, even if the wafer W is displaced in the horizontal direction during polishing, the submergence of the outer peripheral portion of the wafer W under the step portion 81 is suppressed.
In this embodiment, the step of the step portion 81 is set to about half of the thickness of the wafer W. However, the wafer is appropriately set according to conditions such as the contact pressure by the lower retainer ring 80 and the elasticity of the polishing pad 24. It is set in a range smaller than the thickness of W.
[0046]
The width of the stepped portion 81 is preferably set in a range of 1.0% to 2.5% with respect to the diameter of the wafer W. That is, if this number is too large, the pad deformation amount increases due to an increase in actual pressure. In the case of 8 ″ φ, 1.0% or more is necessary because the width of the T region is 2 mm or more.
However, depending on the wafer material and polishing conditions, the above ranges may be excluded.
[0047]
【The invention's effect】
The present invention has the following effects.
(1) According to the wafer polishing apparatus of the first aspect, the lower surface of the retainer ring Groove near the inner periphery of Therefore, the raised part of the polishing pad that occurs near the inside of the retainer ring is partially Groove The bulging portion in the vicinity of the inner side of the retainer ring can be made smaller by guiding it to the outside in the radial direction. Therefore, the wavy deformation of the polishing pad can be suppressed, over-polishing of the outer peripheral portion of the wafer can be mitigated, and polishing uniformity can be further improved.
[0048]
In addition, the rising part, A part of the groove is raised and dispersed in the groove portion, and the bulging portion generated in the vicinity of the inner side of the retainer ring is reduced, thereby suppressing the wavy deformation. Furthermore, since the groove portion is arranged closer to the inner periphery of the lower surface, and the lower surface of the retainer ring is divided into an outer pressing surface and an inner pressing surface by the groove portion, the contact pressure applied to the vicinity of the inner side of the retainer ring is reduced. The raised portion can be further reduced.
[0049]
(2) Claim 2 According to the wafer polisher It is arranged on the inner peripheral side of the lower surface of the retainer ring and is set to a level difference that is at least smaller than the thickness of the wafer. Therefore, the raised portion is generated in the stepped portion and escapes outward in the radial direction from the outer peripheral portion of the wafer, so that the influence on the polishing by the raised portion can be suppressed. Furthermore, since the step is set to a step smaller than the thickness of the wafer, even if the wafer is displaced in the horizontal direction, it is possible to suppress the submergence of the outer periphery of the wafer below the step, and the wafer support function is also good. Can be maintained.
(3) Claim 3 According to the wafer polishing apparatus, since the width of the stepped portion is set in the range of 1.0% to 2.5% with respect to the diameter of the wafer, more preferably, the influence of the raised portion on the polishing is affected. Can be suppressed.
[Brief description of the drawings]
FIG. 1 is a front view showing a first embodiment of a wafer polishing apparatus according to the present invention.
FIG. 2 is a plan view showing an arrangement state of a wafer holding head and a platen in the first embodiment of the wafer polishing apparatus according to the present invention.
FIG. 3 is a sectional view showing a wafer holding head in the first embodiment of the wafer polishing apparatus according to the present invention.
FIG. 4 is a cross-sectional view showing a retainer ring in the first embodiment of the wafer polishing apparatus according to the present invention.
FIG. 5 is an enlarged cross-sectional view showing a main part of the retainer ring in the first embodiment of the wafer polishing apparatus according to the present invention.
FIG. 6 is an enlarged schematic cross-sectional view illustrating a main part for explaining a raised portion at the time of polishing in a conventional example of a wafer polishing apparatus according to the present invention.
FIG. 7 is an enlarged schematic cross-sectional view of a main part for explaining a swelled portion during polishing in the first embodiment of the wafer polishing apparatus according to the present invention.
FIG. 8 is a schematic cross-sectional view enlarging a main part for explaining a raised portion at the time of polishing in the second embodiment of the wafer polishing apparatus according to the present invention.
FIG. 9 is a cross-sectional view showing a retainer ring in a second embodiment of a wafer polishing apparatus according to the present invention.
FIG. 10 is an enlarged cross-sectional view showing a main part showing a retainer ring in a second embodiment of a wafer polishing apparatus according to the present invention.
FIG. 11 is a cross-sectional view showing a wafer holding head in a conventional example of a wafer polishing apparatus according to the present invention.
FIG. 12 is a schematic view showing a problem of a conventional apparatus.
[Explanation of symbols]
22 Platen
24 Polishing pad
24A Hard surface layer
24B Elastic support layer
30 carousel (head drive mechanism)
32 Wafer holding head
34 Head body
44 Diaphragm
46 Career
50 Retainer ring
70 Groove (flank)
71 Outer pressing surface
72 Inner pressing surface
80 Retainer ring
81 steps
T, T1, T2 Swelling part (wave deformation)
S Wafer adhesion sheet
W wafer

Claims (3)

A platen having a polishing pad affixed to the surface, one or more wafer holding heads that hold one side of the wafer to be polished and abut the other side of the wafer against the polishing pad, and drive the wafer holding heads A head driving mechanism for polishing the other surface of the wafer with the polishing pad, and the wafer holding head includes a disk-shaped carrier for holding the one surface of the wafer to be polished, and an outer periphery of the carrier. The retainer ring is concentrically disposed on the lower surface of the retainer ring. is over the entire circumference to the inner circumference near the groove to release the raised part of the polishing pad caused near the inside of the retainer ring is formed during polishing , 1 wherein along with the lower surface of the retainer ring is divided into an inner pressing surface of the smaller area than the outer pressing surface and the outer pressing surface by the groove portion, 0.5% of the width of the groove portion of the wafer diameter. A wafer polishing apparatus characterized in that it is set in a range of 0%.   A platen having a polishing pad affixed to the surface, one or more wafer holding heads that hold one side of the wafer to be polished and abut the other side of the wafer against the polishing pad, and drive the wafer holding heads A head driving mechanism for polishing the other surface of the wafer with the polishing pad, and the wafer holding head includes a disk-shaped carrier for holding the one surface of the wafer to be polished, and an outer periphery of the carrier. The retainer ring is concentrically disposed on the lower surface of the retainer ring.The retainer ring is configured to be displaceable in the head axial direction, and its lower surface is configured to abut against the polishing pad during polishing. Is formed with a stepped part over the entire circumference to escape the raised part of the polishing pad generated near the inside of the retainer ring during polishing. The wafer polishing apparatus characterized by being set than the thickness to a small level difference of at least the wafer disposed on the inner peripheral side of the lower surface of the retainer ring. The wafer polishing apparatus according to claim 2. In the wafer polishing apparatus, the width of the step portion is set in a range of 1.0% to 2.5% with respect to the diameter of the wafer.

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