Polishing surface constituting member and polishing apparatus using the polishing surface constituting member

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a polishing surface constituting member used in a polishing apparatus for polishing an object to be polished, e.g. a semiconductor substrate. More particularly, the present invention relates to a polishing surface constituting member suitable for polishing a surface of a polishing object flat and uniformly without overpolishing at the edge of the object. The present invention also relates to a polishing apparatus using the polishing surface constituting member.

[0002] A polishing apparatus for polishing an object to be polished, e.g. a semiconductor substrate, has a polishing table with a polishing surface constituting member bonded to the upper surface thereof. The polishing apparatus further has a top ring for holding a substrate as an object to be polished, and an abrasive liquid supply nozzle. While an abrasive liquid is being supplied onto the polishing surface constituting member from the abrasive liquid supply nozzle, the substrate to be polished that is held by the top ring is pressed against the polishing surface constituting member under a predetermined pressure, and the polishing table and the top ring are rotated to cause relative movement between the polishing surface constituting member and the substrate, thereby polishing the substrate. It should be noted that the term “polishing surface constituting member” as used herein means a polishing pad, an abrasive wheel having a polishing surface, a sheet-shaped member containing abrasive grains, etc.

[0003] As the degree of integration of semiconductor devices increases, it is increasingly demanded that substrates to be polished, e.g. semiconductor substrates, should be polished flat and uniformly. To polish a substrate flat and uniformly, the general practice is to press the whole surface of the substrate against the surface of a polishing surface constituting member under a uniform pressure. However, because the polishing surface constituting member has elasticity, as shown in FIG. 12, the polishing surface constituting member 20 is deformed during polishing in the vicinity of a portion thereof that comes in contact with the edge 10a of the substrate 10. Accordingly, the surface of the substrate 10 to be polished cannot uniformly be pressed against the polishing surface constituting member 20. More specifically, the polishing surface constituting member 20 is deformed downwardly by being pressed with the substrate 10 being polished. At this time, a particularly high pressure is applied to the edge 10a of the substrate 10, causing the edge 10a to be overpolished. This is known as “edge rounding”.

[0004] Further, in the vicinity of the edge 10a of the substrate 10, the polishing surface constituting member 20 cannot follow the geometry of the substrate 10 because it is deformed downwardly by the edge 10a of the substrate 10. That is, a rebound region occurs as shown in FIG. 13. Accordingly, at the rebound region with a width D, the pressure applied to the polishing surface constituting member 20 reduces, and hence the polishing rate reduces. Consequently, flat and uniform polishing cannot be attained. It should be noted that FIG. 13 is an enlarged view of part A in FIG. 12.

[0005] As shown in FIG. 14, a polishing pad 20-1 generally used as the polishing surface constituting member 20 has a double-layer structure including a relatively hard first layer 21 formed by using IC-1000 or the like, and a relatively soft second layer 22 made of SUBA400 or the like. In the polishing pad 20-1, the relatively hard first layer 21 forms a surface that comes in contact with the substrate 10 to polish it. The relatively soft second layer 22, which is an underlying layer, allows the first layer 21 to follow surface waviness or the like of the substrate 10. However, because the first layer 21 is a relatively hard layer, follow-up capability undesirably reduces in the vicinity of the edge 10a of the substrate 10. Consequently, the width D of the rebound region becomes about 6 mm. Thus, overpolishing at the edge 10a of the substrate 10 cannot be reduced.

[0006] In general, the polishing surface constituting member 20 needs to retain an abrasive liquid. Therefore, the surface of the polishing surface constituting member 20 is provided with a large number of grooves 23 in a lattice configuration as shown in FIG. 15, or provided with a large number of holes 24 as shown in FIG. 16. However, the grooves 23 and the holes 24 are not provided to prevent overpolishing at the edge 10a of the substrate 10 and hence have no function of preventing overpolishing at the edge 10a of the substrate 10.

SUMMARY OF THE INVENTION

[0007] The present invention has been made in view of the above-described circumstances.

[0008] Accordingly, one purpose of the present invention is to provide a polishing surface constituting member capable of polishing a surface of a polishing object flat and uniformly with minimal overpolishing at the edge of the object.

[0009] Another purpose of the present invention is to provide a polishing apparatus using the above-described polishing surface constituting member.

[0010] According to a first aspect of the present invention, a polishing surface constituting member is provided for polishing an object to be polished by pressing the object against the polishing surface constituting member under a predetermined pressure and causing relative movement between the object and the polishing surface constituting member. A surface of the polishing surface constituting member that comes in contact with the object is provided with grooves at a predetermined pitch or provided with projections in a predetermined configuration.

[0011] According to the above-described structure of the present invention, the surface of the polishing surface constituting member that comes in contact with the object to be polished is provided with grooves at a predetermined pitch or provided with projections in a predetermined configuration. Therefore, the follow-up capability of the polishing surface constituting member with respect to the object being polished is improved, and overpolishing at the edge of the object to be polished is minimized. Accordingly, the surface of the object can be polished flat and uniformly.

[0012] In addition, the present invention provides a polishing surface constituting member for polishing an object to be polished by pressing the object against the polishing surface constituting member under a predetermined pressure and causing relative movement between the object and the polishing surface constituting member. A surface of the polishing surface constituting member that comes in contact with the object is provided with a large number of disk-shaped projections at a predetermined pitch suitable for improving follow-up capability with respect to the object being polished and for preventing overpolishing at the edge of the object, whereby grooves are provided between the disk-shaped projections.

[0013] According to the above-described structure of the present invention, the surface of the polishing surface constituting member that comes in contact with the object to be polished is provided with a large number of disk-shaped projections at a predetermined pitch suitable for improving follow-up capability with respect to the object being polished and for preventing overpolishing at the edge of the object, whereby grooves are provided between the disk-shaped projections. Therefore, the follow-up capability of the polishing surface constituting member with respect to the object being polished is improved, and overpolishing at the edge of the object to be polished is minimized. Accordingly, the surface of the object can be polished flat and uniformly.

[0014] According to a second aspect of the present invention, the polishing surface constituting member according to the first aspect of the present invention has a laminated structure including at least two layers, and the grooves or grooves provided between the projections extend to the surface of a layer of the polishing surface constituting member immediately subsequent to a layer thereof that comes in contact with the object to be polished.

[0015] According to the above-described structure of the present invention, the polishing surface constituting member has a laminated structure including at least two layers, and the grooves or grooves provided between the projections extend to the surface of a layer of the polishing surface constituting member immediately subsequent to a layer thereof that comes in contact with the object to be polished. Therefore, the follow-up capability of the polishing surface constituting member with respect to the object being polished is further improved, and overpolishing at the edge of the object to be polished is further minimized. Accordingly, the surface of the object can be polished even more flat and uniformly.

[0016] According to a third aspect of the present invention, the polishing surface constituting member according to the first aspect of the present invention has a laminated structure including at least two layers, and the grooves or grooves provided between the projections extend into a layer of the polishing surface constituting member immediately subsequent to a layer thereof that comes in contact with the object to be polished.

[0017] According to the above-described structure of the present invention, the polishing surface constituting member has a laminated structure including at least two layers, and the grooves or grooves provided between the projections extend into a layer of the polishing surface constituting member immediately subsequent to a layer thereof that comes in contact with the object to be polished. Therefore, the width of the grooves can be narrowed without degrading the follow-up capability of the polishing surface constituting member with respect to the object being polished, and the surface of the object can be polished still more flat and uniformly.

[0018] According to a fourth aspect of the present invention, the polishing surface constituting member according to the second or third aspect of the present invention is arranged such that at least one of underlying layers of the polishing surface constituting member subsequent to the layer thereof that comes in contact with the object to be polished is a layer pressurized by a fluid.

[0019] According to the above-described structure of the present invention, at least one of underlying layers of the polishing surface constituting member subsequent to the layer thereof that comes in contact with the object to be polished is a layer pressurized by a fluid. Therefore, the follow-up capability of the polishing surface constituting member with respect to the object being polished is further improved by properly varying the pressure of the fluid. Accordingly, overpolishing at the edge of the object to be polished is minimized, and the surface of the object can be polished flat and uniformly. Even if the layer of the polishing surface constituting member that comes in contact with the object to be polished is reduced in thickness, stable polishing can be performed because the pressure applied to the object to be polished can be held constant.

[0020] According to a fifth aspect of the present invention, there is provided a polishing apparatus for polishing an object to be polished by pressing the object against a polishing surface constituting member on a polishing table under a predetermined pressure and causing relative movement between the object and the polishing surface constituting member. The polishing surface constituting member of the polishing apparatus is the polishing surface constituting member according to any one of the first to fourth aspects of the present invention.

[0021] According to the above-described structure of the present invention, the polishing surface constituting member according to any one of the first to fourth aspects of the present invention is used as the polishing surface constituting member of the polishing apparatus. Therefore, the polishing apparatus can polish the surface of the object flat and uniformly.

[0022] The above and other functions, features and advantages of the present invention will become more apparent from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]
FIG. 1 is a cross-section of an essential part of a polishing pad used as a polishing surface constituting member according to the present invention, showing a structural example thereof.

[0024]
FIG. 2 is a graph showing the results of polishing a substrate as an object to be polished.

[0025]
FIG. 3 is an enlarged view of part B in FIG. 2.

[0026]
FIG. 4 is a partly-sectioned perspective of an essential part of a polishing pad used as a polishing surface constituting member according to the present invention, showing another structural example thereof.

[0027]
FIG. 5 is a cross-section showing an essential part of another embodiment of the polishing surface constituting member according to the present invention.

[0028]
FIG. 6 is a cross-section showing an essential part of still another embodiment of the polishing surface constituting member according to the present invention.

[0029]
FIG. 7 is a cross-section showing an essential part of a further embodiment of the polishing surface constituting member according to the present invention.

[0030]
FIG. 8 is a schematic sectional view showing a further embodiment of the polishing surface constituting member according to the present invention.

[0031]
FIG. 9 is a diagram showing a structural example of a polishing apparatus using the polishing surface constituting member according to the present invention.

[0032]
FIG. 10 is a perspective showing another structural example of a polishing apparatus using the polishing surface constituting member according to the present invention.

[0033]
FIG. 11 is a diagram showing still another structural example of a polishing apparatus using the polishing surface constituting member according to the present invention.

[0034]
FIG. 12 is a diagram showing problems associated with a conventional polishing surface constituting member.

[0035]
FIG. 13 is an enlarged view of part A in FIG. 12.

[0036]
FIG. 14 is a cross-section of a conventional polishing pad.

[0037]
FIG. 15 is a diagram showing a structural example of a conventional polishing surface constituting member.

[0038]
FIG. 16 is a diagram showing another structural example of a conventional polishing surface constituting member.

EXPLANATION OF REFERENCE NUMERALS

[0039]

1
: polishing surface constituting member

[0040]

1
-1: polishing pad

[0041]

1
-2: polishing sheet

[0042]

2
: first layer

[0043]

3
: second layer

[0044]

4
: grooves

[0045]

5
: projections

[0046]

6
: intermediate layer

[0047]

7
: layer member

[0048]

7

a
: fluid inlet

[0049]

10
: substrate to be polished

[0050]

11
: turntable

[0051]

12
: top ring

[0052]

13
: abrasive liquid supply nozzle

[0053]

14
: top ring shaft

[0054]

15
: oscillating arm

[0055]

16
: motor

[0056]

17
: guide ring

[0057]

20
: polishing surface constituting member

[0058]

20
-1: polishing pad

[0059]

30
: back plate

[0060]

31
: polishing sheet feed drum

[0061]

32
: polishing sheet take-up drum

[0062]

33
: polishing table

[0063]

34
: rotary drum

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-section showing an essential part of a polishing pad 1-1 used as a polishing surface constituting member 1 according to the present invention. The polishing pad 1-1 is composed of two layers, i.e. a first layer 2, and a second layer 3.

[0065] The first layer 2 is made of a relatively hard material, e.g. IC-1000. The surface of the first layer 2 is provided with grooves 4 extending short of the surface of the second layer 3 in such a manner that the pitch (interval) L of the grooves 4 is L=5 mm. The second layer 3 is made of a relatively soft material, e.g. SUBA400.

[0066] A substrate 10 to be polished is pressed against the polishing pad 1-1 under a predetermined pressure and polished by relative movement between them. During the polishing process, it becomes easy for the polishing pad 1-1 to follow the substrate 10 because the first layer 2 is thin in thickness at portions where the grooves 4 are provided. FIG. 2 is a graph showing the results of polishing the substrate 10. FIG. 3 is an enlarged view of part B in FIG. 2. In this embodiment, the grooves 4 provided in the polishing pad 1-1 each have a width of 1 mm and a depth of 1 mm, and the substrate 10 to be polished has a circular shape with an outer diameter of 8 inches. In FIGS. 2 and 3, the abscissa axis represents the distance (mm) from the center of the substrate 10, and the ordinate axis represents the stock removal (Polishing Amount) (Å) in polishing of the substrate 10.

[0067] It will be understood from FIGS. 2 and 3 that when the pitch L is 5 mm, overpolishing at an edge 10a of the substrate 10 that extends over a range of about 5 mm (and a range of about 1 mm not to be measured) from the outer periphery thereof is reduced in comparison to a case where the pitch L is 10 mm. The reason for this is that the occurrence of a rebound region in the vicinity of the edge 10a of the substrate 10 is suppressed owing to an improvement in follow-up capability of the polishing pad 1-1. Also, it should be noted that a rebound of the polishing pad 1-1 at the edge 10a that extends over a range of about 3 mm from the outer periphery of the substrate 10 is further reduced when the pitch L is 3 mm (see FIG. 3). Thus, overpolishing and the rebound of the polishing pad 1-1 at the edge 10a can be reduced by setting the pitch L of the grooves 4 in the polishing pad 1-1 at 5 mm or less.

[0068] It should be noted that there is no particular restriction on the configuration of the grooves 4 provided in the surface of the polishing pad 1-1. As shown in FIG. 15, a large number of grooves 4 may be provided in a lattice configuration. Alternatively, grooves 4 may be formed by providing a large number of disk-shaped projections 5 as shown in FIG. 4.

[0069] The depth of the grooves 4 provided in the surface of the polishing surface constituting member 1 is not necessarily limited to the one that is short of the surface of the second layer 3. As shown in FIG. 5, the grooves 4 may extend to the surface of the second layer 3. Alternatively, the grooves 4 may extend into the second layer 3 as shown in FIG. 6. In a case where the grooves 4 are provided to extend to the surface of the second layer 3 of the polishing surface constituting member 1, the follow-up capability of the polishing surface constituting member 1 is further improved, and the occurrence of a rebound region in the vicinity of the edge 10a of the substrate 10 is further suppressed. When the grooves 4 are provided to extend into the second layer 3 of the polishing surface constituting member 1, the follow-up capability of the polishing surface constituting member 1 will not be degraded even if the width of the grooves 4 is narrowed. Further, because the area with which the first layer 2 comes in contact with the substrate 10 increases, the surface of the substrate 10 can be polished even more flat and even more uniformly.

[0070]
FIG. 7 is a cross-section showing an essential part of a further embodiment of the polishing surface constituting member according to the present invention. The polishing surface constituting member 1 according to this embodiment has a triple-layer structure in which an elastic intermediate layer 6 made, for example, of rubber or urethane foam is provided between a relatively hard first layer 2 and a relatively soft second layer 3. Provision of the intermediate layer 6 makes it possible to minimize rapid changes in elasticity even when the first layer 2 is reduced in thickness. Regarding the depth of the grooves 4 in this embodiment, the grooves 4 may be provided to extend through the first layer 2. Alternatively, the grooves 4 may be provided to extend into the intermediate layer 6 or as far as the inside of the second layer 3. Although in this embodiment the polishing surface constituting member 1 has a triple-layer structure, the present invention is not necessarily limited thereto. The polishing surface constituting member 1 may have a laminated structure including more than three layers.

[0071]
FIG. 8 is a schematic sectional view showing a further embodiment of the polishing surface constituting member according to the present invention. The polishing surface constituting member 1 according to this embodiment has a layer member 7 as a layer underlying a relatively hard first layer 2. The layer member 7 is capable of accommodating a fluid F therein. The layer member 7 can be expanded or contracted by varying the pressure of the fluid accommodated therein. More specifically, the layer member 7 expands as the pressure therein is increased by introducing the fluid into the layer member 7 from a fluid inlet 7a. During polishing of the substrate 10, the pressure in the layer member 7 is varied appropriately, whereby it is possible to further improve the follow-up capability of the polishing surface constituting member 1 with respect to the substrate 10 being polished. Even when the first layer 2 is reduced in thickness, stable polishing can be performed because the pressure applied to the substrate 10 can be held constant. It should be noted that a polishing surface constituting member 1 having a laminated structure including three or more layers can also perform stable polishing by having the layer member 7 as the lowermost layer.

[0072] Next, a polishing apparatus using the polishing surface constituting member according to the present invention will be described. FIG. 9 is a diagram showing a structural example of a polishing apparatus using the polishing surface constituting member according to the present invention. The polishing apparatus includes a turntable 11 having the polishing surface constituting member 1 according to the present invention bonded to the upper surface thereof. The polishing apparatus further includes a top ring 12 for holding a substrate 10 to be polished in such a manner that the substrate 10 is rotatable and capable of being pressed against the polishing surface constituting member 1. Further, the polishing apparatus includes an abrasive liquid supply nozzle 13 for supplying an abrasive liquid Q to the polishing surface constituting member 1. The top ring 12 is connected to a top ring shaft 14. The top ring shaft 14 is rotatable by a rotating device (not shown), e.g. a motor, provided in an oscillating arm 15. The top ring shaft 14 is also vertically movable by a vertically moving mechanism (not shown), e.g. a cylinder, provided in the oscillating arm 15. The top ring shaft 14 is supported by the oscillating arm 15 through bearings (not shown). The oscillating arm 15 is supported in such a manner as to be oscillatable, together with the top ring 12 as one unit, over a predetermined angle range in a horizontal plane parallel to the polishing surface constituting member 1 by a motor 16.

[0073] The top ring 12 has the substrate 10 attached on the lower surface thereof by a holding device (not shown). The top ring 12 has a cylindrical guide ring 17 provided on the outer periphery thereof to prevent the substrate 10 from becoming dislodged from the lower surface of the top ring 12 during polishing. The guide ring 17 is secured to the top ring 12. The lower end surface of the guide ring 17 projects from the substrate holding surface of the top ring 12 so that the substrate 10 is held in a recess defined inside the projecting lower end of the guide ring 17.

[0074] With the above-described arrangement, the substrate 10 to be polished is attached on the lower surface of the top ring 12. The substrate 10 is pressed against the polishing surface constituting member 1 on the turntable 11 by the top ring 12, and the turntable 11 and the top ring 12 are rotated to cause relative movement between the polishing surface constituting member 1 and the substrate 10, thereby polishing the substrate 10. At this time, the abrasive liquid Q is supplied onto the polishing surface constituting member 1 from the abrasive liquid supply nozzle 13. A liquid containing abrasive grains, for example, fine silica particles, is used as the abrasive liquid Q. The polishing apparatus can polish the surface of the substrate 10 flat and uniformly because it uses the polishing surface constituting member 1 according to the present invention.

[0075] It should be noted that the polishing apparatus using the polishing surface constituting member 1 according to the present invention is not necessarily limited to that shown in FIG. 9. The polishing surface constituting member 1 according to the present invention is applicable to any polishing apparatus wherein a substrate to be polished is pressed against a polishing pad and polished by relative movement therebetween.

[0076] For example, the present invention may be applied to a polishing apparatus as shown in FIG. 10. The polishing apparatus has a polishing table 33 arranged such that a polishing sheet 1-2 as a polishing surface constituting member 1 unwound from a polishing sheet feed drum 31 is wound onto a polishing sheet take-up drum 32 via a back plate 30. The polishing apparatus further has a top ring 12. A substrate 10 to be polished that is held by the rotating top ring 12 is pressed against the polishing sheet 1-2 passing over the upper surface of the back plate 30 of the polishing table 33, thereby polishing the substrate 10.

[0077] The present invention may also be applied to a polishing apparatus as shown in FIG. 11. The polishing apparatus has a rotary drum 34 having a polishing sheet 1-2 bonded to the outer peripheral surface thereof as a polishing surface constituting member 1. The polishing apparatus further has a top ring 12. A substrate 10 to be polished that is held by the rotating top ring 12 is pressed against the polishing sheet 1-2 on the rotary drum 34, thereby polishing the substrate 10.

[0078] In the polishing apparatus of the present invention, the polishing surface constituting member 1 confusing-consider eliminating which contacts and polishes the surface of the substrate 10 to be polished can be constituted by a grinder or a pad or a sheet which contains abrasive grains.

[0079] As has been described above, the present invention provides the following advantages.

[0080] According to the first aspect of the present invention, the surface of the polishing surface constituting member that comes in contact with an object to be polished is provided with grooves at a predetermined pitch or provided with projections in a predetermined configuration. Therefore, the follow-up capability of the polishing surface constituting member with respect to the object being polished is improved, and overpolishing at the edge of the object to be polished is minimized. Accordingly, the surface of the object can be polished flat and uniformly.

[0081] According to the second aspect of the present invention, the polishing surface constituting member has a laminated structure including at least two layers, and the grooves or grooves provided between the projections extend to the surface of a layer of the polishing surface constituting member immediately subsequent to a layer thereof that comes in contact with the object to be polished. Therefore, the follow-up capability of the polishing surface constituting member with respect to the object being polished is further improved, and overpolishing at the edge of the object to be polished is further minimized. Accordingly, the surface of the object can be polished even more flat and uniformly.

[0082] According to the third aspect of the present invention, the polishing surface constituting member has a laminated structure including at least two layers, and the grooves or grooves provided between the projections extend into a layer of the polishing surface constituting member immediately subsequent to a layer thereof that comes in contact with the object to be polished. Therefore, the width of the grooves can be narrowed without degrading the follow-up capability of the polishing surface constituting member with respect to the object being polished, and the surface of the object can be polished still more flat and uniformly.

[0083] According to the fourth aspect of the present invention, at least one of underlying layers of the polishing surface constituting member subsequent to the layer thereof that comes in contact with the object to be polished is a layer pressurized by a fluid. Therefore, the follow-up capability of the polishing surface constituting member with respect to the object being polished is further improved by properly varying the pressure of the fluid. Accordingly, overpolishing at the edge of the object to be polished is minimized, and the surface of the object can be polished flat and uniformly. Even if the layer of the polishing surface constituting member that comes in contact with the object to be polished is reduced in thickness, stable polishing can be performed because the pressure applied to the object to be polished can be held constant.

[0084] According to the fifth aspect of the present invention, the polishing apparatus uses the polishing surface constituting member according to any one of the first to fourth aspects of the present invention. Therefore, the polishing apparatus can polish the surface of the object flat and uniformly.

[0085] It should be noted that the present invention is not necessarily limited to the foregoing embodiments but can be modified in a variety of ways.

Polishing surface constituting member and polishing apparatus using the polishing surface constituting member

Information

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Date Filed

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CPC

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Abstract

Description

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Priority Claims (1)