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Publication numberUS20020072307 A1
Publication typeApplication
Application numberUS 09/736,137
Publication dateJun 13, 2002
Filing dateDec 13, 2000
Priority dateDec 13, 2000
Publication number09736137, 736137, US 2002/0072307 A1, US 2002/072307 A1, US 20020072307 A1, US 20020072307A1, US 2002072307 A1, US 2002072307A1, US-A1-20020072307, US-A1-2002072307, US2002/0072307A1, US2002/072307A1, US20020072307 A1, US20020072307A1, US2002072307 A1, US2002072307A1
InventorsClinton Fruitman, Timothy Dyer
Original AssigneeFruitman Clinton O., Dyer Timothy S.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus and method for chemical mechanical planarization using a fixed-abrasive polishing pad
US 20020072307 A1
Abstract
A homogeneous polishing pad for chemical mechanical planarization of a workpiece has a thickness of at least about 1 millimeter. The polishing pad is friable and includes an abrasive material that is uniformly distributed throughout the pad. The abrasive material exhibits abrasive behavior that does not degrade significantly as the pad wears during planarization and conditioning.
In another embodiment, the homogenous polishing pad has an average wear rate in the range of from less than 1 μm/minute to about 10 μm/minute.
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Claims(71)
We claim:
1. A homogenous polishing pad for chemical mechanical planarization of a workpiece having a thickness of at least about 1 millimeter, wherein said pad is friable and comprises an abrasive material uniformly distributed throughout said pad, and wherein said abrasive material has abrasive characteristics that do not degrade significantly as said pad wears during planarization and conditioning.
2. The polishing pad of claim 1, further comprising a resin-bonded material.
3. The polishing pad of claim 1, further comprising a ceramic-bonded material.
4. The polishing pad of claim 1 having a thickness in the range of from about 0.5 inches to about 1.5 inches.
5. The polishing pad of claim 1 having a thickness of about one inch.
6. The polishing pad of claim 1, wherein said polishing pad is subjected to motion relative to said workpiece.
7. The polishing pad of claim 6, wherein said motion is selected from the group comprising linear motion, orbital motion, rotary motion, linear and orbital motion, linear and rotary motion, orbital and rotary motion, and linear, orbital and rotary motion.
8. The polishing pad of claim 1, further comprising at least one channel through which a fluid may flow.
9. The polishing pad of claim 1, wherein said polishing pad comprises pores through which a fluid may flow.
10. The polishing pad of claim 1 having an average wear rate in the range of from less than 1 μm/minute to about 10 μm/minute.
11. A method of chemical mechanical planarization of a workpiece comprising:
providing a homogenous polishing pad having a thickness of at least about 1 millimeter and having a polishing surface, wherein said polishing pad is friable and comprises abrasive material uniformly distributed throughout said polishing pad, and wherein said abrasive material exhibits abrasive behavior that does not degrade significantly as said polishing pad wears during planarizaton and conditioning; and
pressing said polishing pad against said workpiece while causing relative motion between said polishing pad and said workpiece.
12. The method of claim 11, further comprising distributing a fluid to said polishing surface of said polishing pad.
13. The method of claim 11, wherein said causing relative motion comprises causing relative motion selected from the group comprising linear motion, orbital motion, rotary motion, linear and orbital motion, linear and rotary motion, orbital and rotary motion, and linear, orbital and rotary motion.
14. The method of claim 11, wherein said providing a homogenous polishing pad further comprises providing a homogenous polishing pad having a thickness in the range of from about 0.5 inches to about 1.5 inches.
15. The method of claim 11, wherein said providing a homogenous polishing pad further comprises providing a homogenous polishing pad having a thickness of about one inch.
16. The method of claim 12, wherein said providing a homogeneous polishing pad further comprises providing a homogeneous polishing pad having at least one channel through which said fluid may flow.
17. The method of claim 12, wherein said providing a homogeneous polishing pad further comprises providing a homogeneous polishing pad having pores through which said fluid may flow.
18. The method of claim 11, wherein said providing a homogeneous polishing pad further comprises providing a homogeneous polishing pad having an average pad wear rate in the range of from less than 1 m/minute to about 10 μm/minute.
19. An apparatus for planarizing a workpiece comprising:
a homogenous polishing pad having a thickness of at least about 1 millimeter, wherein said pad is friable and comprises abrasive material uniformly distributed throughout, and wherein said abrasive material exhibits abrasive behavior that does not degrade significantly as said homogeneous polishing pad wears during planarization and conditioning; and
a workpiece carrier configured to carry a workpiece and press said workpiece against said homogeneous polishing pad.
20. The apparatus of claim 19, wherein said polishing pad has a thickness in the range of from about 0.5 inches to about 1.5 inches.
21. The apparatus of claim 19, wherein said polishing pad has a thickness of about one inch.
22. The apparatus of claim 19, further comprising a drive assembly configured to cause relative motion between said polishing pad and said workpiece.
23. The apparatus of claim 22, wherein said relative motion is selected from the group comprising linear motion, orbital motion, rotary motion, linear and orbital motion, linear and rotary motion, orbital and rotary motion, and linear, orbital and rotary motion.
24. The apparatus of claim 19, wherein said workpiece carrier comprises a central axis and is configured to rotate about said central axis.
25. The apparatus of claim 19, wherein said homogeneous polishing pad has a polishing surface and at least one channel wherein fluids are fed to said polishing surface through said at least one channel.
26. The apparatus of claim 25, further comprising a platen configured to support said polishing pad.
27. The apparatus of claim 26, wherein said platen comprises at least one conduit and wherein fluids are fed to said polishing surface through said at least one conduit of said platen and said at least one channel of said homogeneous polishing pad.
28. The apparatus of claim 19, wherein said homogeneous polishing pad has a polishing surface and comprises pores wherein fluids are fed to said polishing surface through said pores.
29. The apparatus of claim 28, further comprising a platen configured to support said polishing pad.
30. The apparatus of claim 29, wherein said platen comprises at least one conduit and wherein fluids are fed to said polishing surface through said at least one conduit of said platen and said pores of said homogeneous polishing pad.
31. The apparatus of claim 19, wherein said homogeneous polishing pad has an average wear rate in the range of from less than 1 μm/minute to about 10 μm/minute.
32. A homogeneous polishing pad for chemical mechanical planarization of a workpiece having an average wear rate in the range of from less than 1 μm/minute to about 10 μm/minute, wherein said pad is friable and comprises an abrasive material uniformly distributed throughout said pad, and wherein said abrasive material has abrasive characteristics that do not degrade significantly as said pad wears during planarization and conditioning.
33. The polishing pad of claim 32, further comprising a resin-bonded material.
34. The polishing pad of claim 32, further comprising a ceramic-bonded material.
35. The polishing pad of claim 32, having a thickness in the range of from about 0.5 inches to about 1.5 inches.
36. The polishing pad of claim 32, having a thickness of about one inch.
37. The polishing pad of claim 32, wherein said polishing pad is subjected to motion relative to said workpiece.
38. The polishing pad of claim 37, wherein said motion is selected from the group comprising linear motion, orbital motion, rotary motion, linear and orbital motion, linear and rotary motion, orbital and rotary motion, and linear, orbital and rotary motion.
39. The polishing pad of claim 32, further comprising at least one channel through which a fluid may flow.
40. The polishing pad of claim 32, further comprising pores through which a fluid may flow.
41. An apparatus for planarizing a workpiece comprising:
a) a plurality of polishing stations wherein at least one of said plurality of polishing stations comprises a homogenous polishing pad having a thickness of at least about 1 millimeter, wherein said homogenous polishing pad is friable and comprises abrasive material uniformly distributed throughout, and wherein said abrasive material has abrasive characteristics that do not degrade significantly as said polishing pad wears during planarization and conditioning;
and
b) a drive assembly connected to said at least one of said plurality of polishing stations and configured to effect a first relative motion between said homogenous polishing pad and said workpiece.
42. The apparatus of claim 41, wherein said first relative motion is selected from the group comprising linear motion, orbital motion, rotary motion, linear and orbital motion, linear and rotary motion, orbital and rotary motion, and linear, orbital and rotary motion.
43. The apparatus of claim 41, wherein said homogenous polishing pad further comprises a resin-bonded material.
44. The apparatus of claim 41, wherein said homogenous polishing pad further comprises a ceramic-bonded material.
45. The apparatus of claim 41, wherein said homogenous polishing pad has a thickness in the range of from about 0.5 inches to about 1.5 inches.
46. The apparatus of claim 41, wherein said homogenous polishing pad has a thickness of about one inch.
47. The apparatus of claim 41, wherein said homogenous polishing pad has a least one channel through which a fluid may flow.
48. The apparatus of claim 41, wherein said polishing pad comprises pores through which a fluid may flow.
49. The apparatus of claim 41, wherein said polishing pad has an average wear rate in the range of from less than 1 μm/minute to about 10 μm/minute.
50. The apparatus of claim 41, further comprising a conditioning assembly configured to condition said homogenous polishing pad after planarization of a workpiece.
51. The apparatus of claim 41, further comprising a conditioning assembly configured to condition said homogenous polishing pad during planarization of a workpiece.
52. The apparatus of claim 41, further comprising a plurality of workpiece carriers, the number of which corresponds to the number of said polishing stations, wherein each of said plurality of workpiece carriers is configured to carry a workpiece and press said workpiece against one of said plurality of polishing stations while causing a second relative motion between said workpiece and said polishing station.
53. The apparatus of claim 52, wherein said second relative motion is selected from the group comprising linear motion, orbital motion, rotary motion, linear and orbital motion, linear and rotary motion, orbital and rotary motion, and linear, orbital and rotary motion.
54. The apparatus of claim 41, wherein said homogenous polishing pad has a polishing surface and at least one channel through which fluids are fed to said polishing surface.
55. The apparatus of claim 54, wherein said at least one of said plurality of polishing stations comprises a platen configured to support said homogenous polishing pad.
56. The apparatus of claim 55, wherein said platen comprises at least one conduit and wherein fluids are fed to said polishing surface through said at least one conduit and said at least one channel of said polishing pad.
57. The apparatus of claim 41, wherein said homogeneous polishing pad has a polishing surface and comprises pores wherein fluids are fed to said polishing surface through said pores.
58. The apparatus of claim 57, further comprising platen configured to support said polishing pad.
59. The apparatus of claim 58, wherein said platen comprises at least one conduit and wherein fluids are fed to said polishing surface through said at least one conduit of said platen and said pores of said homogeneous polishing pad.
60. An apparatus for planarizing a workpiece comprising:
a homogeneous polishing pad, wherein said polishing pad is friable and has abrasive material uniformly distributed throughout, and wherein said abrasive material exhibits abrasive behavior that does not degrade significantly as said homogeneous polishing pad wears during planarization and conditioning;
a drive assembly configured to move said polishing pad in an orbital pattern; and
a workpiece carrier configured to carry a workpiece and press said workpiece against said homogeneous polishing pad.
61. The apparatus of claim 60, wherein said polishing pad has a thickness of at least 1 millimeter.
62. The apparatus of claim 60, wherein said polishing pad has a thickness in the range of from about 0.5 inches to about 1.5 inches.
63. The apparatus of claim 60, wherein said polishing pad has a thickness of about one inch.
64. The apparatus of claim 60, wherein said workpiece carrier comprises a central axis and is configured to rotate about said central axis.
65. The apparatus of claim 60, wherein said homogeneous polishing pad has a polishing surface and at least one channel wherein fluids are fed to said polishing surface through said at least one channel.
66. The apparatus of claim 65, further comprising a platen configured to support the polishing pad.
67. The apparatus of claim 66, wherein said platen comprises at least one conduit and wherein a fluid is fed to said polishing surface through said at least one conduit and said at least one channel.
68. The apparatus of claim 60, wherein said homogeneous polishing pad has pores through which a fluid may flow.
69. The apparatus of claim 72, further comprising a platen configured to support the polishing pad.
70. The apparatus of claim 69, wherein said platen comprises at least one conduit and wherein a fluid is fed to said polishing surface through said at least one conduit and said pores.
71. The apparatus of claim 60, wherein said homogeneous polishing pad has an average wear rate in the range from less than 1 μm/minute to about 10 μm/minute.
Description
TECHNICAL FIELD

[0001] The present invention relates, generally, to the chemical mechanical planarization of a workpiece and, more particularly, to the chemical mechanical planarization of a workpiece using a fixed-abrasive polishing pad.

BACKGROUND OF THE INVENTION

[0002] Chemical mechanical planarization (“CMP”) is widely used in the microelectronics industry, particularly for local and global planarization of VLSI devices with sub-micron geometries. A typical CMP process involves polishing back built-up layers of dielectrics and conductors on integrated circuit chips during manufacture.

[0003] More particularly, a resinous polishing pad having a cellular structure is traditionally employed in conjunction with a slurry, for example, a water-based slurry comprising colloidal silica particles. When pressure is applied between the polishing pad and the workpiece (e.g., silicon wafer) being polished, mechanical stresses are concentrated on the exposed edges of the adjoining cells in the cellular pad. Abrasive particles within the slurry concentrated on these edges tend to create zones of localized stress at the workpiece in the vicinity of the exposed edges of the polishing pad. This localized pressure creates mechanical strain on the chemical bonds comprising the surface being polished, rendering the chemical bonds more susceptible to chemical attack or corrosion (e.g., stress corrosion). Consequently, microscopic regions are removed from the surface being polished, enhancing planarity of the polished surface. See, for example, Arai et al., U.S. Pat. No. 5,099,614, issued March 1992; Karlsrud, U.S. Pat. No. 5,498,196, issued March 1996; Arai et al., U.S. Pat. No. 4,805,348, issued February 1989; Karlsrud et al., U.S. Pat. No. 5,329,732, issued July 1994; and Karlsrud et al., U.S. Pat. No. 5,498,199, issued March 1996, for further discussion of presently known lapping and planarization techniques. By this reference, the entire disclosures of the foregoing patents are hereby incorporated herein.

[0004] As the size of microelectronic structures used in integrated circuits decreases to sub-half-micron levels, and as the number of microelectronic structures on current and future generation integrated circuits increases, the degree of planarity required increases dramatically. The high degree of accuracy of current lithographic techniques for smaller devices requires increasingly flatter surfaces. However, presently known polishing techniques are believed to be inadequate to produce the degree of local planarity and global uniformity across the relatively large surfaces of silicon wafers used in integrated circuits, particularly for future generations.

[0005] In conventional CMP apparatus, the entire surfaces of the polishing pads are used to planarize each workpiece, with the result that initially the workpiece sees a totally fresh pad while at the end of the process the workpiece sees a pad in glazed condition. In addition, during polishing, the polishing pad wears unevenly, developing worn and glazed tracks that result in nonuniform polishing of the workpiece. In order to minimize these problems, it is well known in the art to recondition the pad between each workpiece, or a certain number of workpieces being processed. However, adding the pad-reconditioning step to the workpiece planarization process typically slows the throughput of the apparatus. Also, while reconditioning the pad does assist in making a glazed pad appear more like a fresh pad, the pad nevertheless undergoes continuous mechanical and chemical degradation through its life, introducing a variable that alters the planarization process from workpiece to workpiece.

[0006] Another problem associated with present CMP systems relates to the slurry delivery process. In conventional applications, the slurry is introduced onto the abrading surface of the polishing pad. However, the workpiece typically acts like a squeegee preventing even distribution of the slurry across the workpiece. As the polishing rate is related in part to the amount of slurry beneath the workpiece during polishing, conventional slurry delivery systems make uniform planarization processes difficult.

[0007] CMP tools that use slowly advancing microabrasive sheets, which do not necessarily require the use of slurries, are also known in the art. While these tools do allow each workpiece to see uniform pad conditions by slowly advancing the microabrasive sheet, these tools introduce several new problems. For example, the known tools do not adequately control the tension in the web resulting in poor mechanical stability of the microabrasive sheet during the planarization process of the workpiece. In addition, the microabrasive particles and clusters may break off during planarization processing, thereby resulting in pitting and scratching of the workpiece.

[0008] Polishing pads formed of abrasive coatings on resilient backings have been demonstrated to improve planarity. For an example of abrasive coatings on resilent backings, see U.S. Pat. No. 5,958,794, issued Sep. 28, 1999 to Bruxvoort et al., incorporated herein by reference Typically, polishing pads of this nature are configured to be positioned proximate a subpad that is situated between the polishing pad and the polishing station platen. The subpad may comprise multiple layers, such as a polycarbonate layer and a resilient foam layer, that attempt to distribute load uniformly to the wafer. However, polishing pads formed of abrasive coatings present a number of disadvantages. For example, such pads are prone to defect generation similar to abrasive sheets. In addition, to maintain the flexibility of the pad, the abrasive coating is formed on a backing or substrate of the pad in relatively thin layers, typically on the order of less than 1 mm. However, with a thin abrasive coating, the polishing pad is only able to polish a few wafers before the pad needs to be replaced, thus decreasing wafer throughput and increasing costs. Increasing the thickness of the coating does not address this disadvantage, as not only is flexibility compromised but the hardness of the coating increases dramatically as the thickness of the abrasive coating increases. If the coating is too hard, it is susceptible to fracturing, thus causing break off of particles and clusters which pit and scratch the workpiece. Further, the hardness of the abrasive coating adversely affects the load distribution on the wafer.

[0009] A need therefore exists for an apparatus and method of planarizing workpieces that enhance the planarization of the workpieces while increasing wafer throughput. A need further exists for an apparatus and method of planarizing workpieces that allow each workpiece to experience similar pad conditions as all other workpieces.

SUMMARY OF THE INVENTION

[0010] These and other aspects of the present invention will become more apparent to those skilled in the art from the following non-limiting detailed description of preferred embodiments of the invention taken with reference to the accompanying figures.

[0011] In accordance with an exemplary embodiment of the present invention, a homogeneous polishing pad for chemical mechanical planarization of a workpiece has a thickness of at least about 1 millimeter. The polishing pad is friable and comprises an abrasive material uniformly distributed throughout the pad which exhibits abrasive behavior that does not degrade significantly as the pad wears during planarization.

[0012] In accordance with another exemplary embodiment of the present invention, the homogeneous polishing pad has at least one channel through which a fluid may flow.

[0013] In accordance with a further exemplary embodiment of the present invention, the homogeneous polishing pad has pores through which a fluid may flow.

[0014] In accordance with yet a further exemplary embodiment of the present invention, the homogeneous polishing pad has an average wear rate in the range of from less than 1 μm/minute to about 10 μm/minute.

[0015] In accordance with another exemplary embodiment, a method of chemical mechanical planarization of a workpiece includes providing a homogeneous polishing pad having a thickness of at least about 1 millimeter. The polishing pad is friable and has abrasive material uniformly distributed throughout. The abrasive material has abrasive characteristics that do not degrade significantly as the polishing pad wears during planarization. The method further includes pressing the polishing pad against the workpiece while causing relative motion between the polishing pad and the workpiece.

[0016] In accordance with a further exemplary embodiment, an apparatus for planarizing a workpiece includes a homogeneous polishing pad having a thickness of at least about 1 millimeter. The polishing pad is friable and has abrasive material uniformly distributed throughout. The abrasive material has abrasive characteristics that do not degrade significantly as the polishing pad wears during planarization. A workpiece carrier is configured to carry a workpiece and press the workpiece against the homogeneous polishing pad.

[0017] In accordance with yet another exemplary embodiment, a homogeneous polishing pad for chemical mechanical planarization of a workpiece has an average wear rate in the range of from less than 1 μm/minute to about 10 μm/minute. The pad is friable and has abrasive material uniformly distributed throughout the pad. The abrasive material has abrasive characteristics that do not degrade significantly as the pad wears during planarization.

[0018] In accordance with yet a further exemplary embodiment of the present invention, an apparatus for planarizing a workpiece includes a plurality of polishing stations. At least one of the plurality of polishing stations has a homogeneous polishing pad having a thickness of at least about 1 millimeter. The homogeneous polishing pad is friable and has abrasive material uniformly distributed throughout. The abrasive material has abrasive characteristics that do not degrade significantly as the polishing pad wears during planarization. A drive assembly is connected to at least one of the plurality of polishing stations and is configured to effect relative motion between the homogenous polishing pad and the workpiece.

[0019] In accordance with another exemplary embodiment of the present invention, an apparatus for planarizing a workpiece includes a homogeneous polishing pad which is friable and has abrasive material uniformly distributed throughout. The abrasive material has abrasive characteristics that do not degrade significantly as the homogeneous polishing pad wears during planarization. A drive assembly is configured to move the polishing pad in an orbital pattern. A workpiece carrier is configured to carry a workpiece and press the workpiece against the homogeneous polishing pad.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0020] Exemplary embodiments of the present invention will hereafter be described in conjunction with the appended drawing figures, wherein like designations denote like elements, and:

[0021]FIG. 1 is a side cross-sectional view of an exemplary embodiment of the fixed-abrasive polishing station of the present invention;

[0022]FIG. 2 is a top view of an exemplary embodiment of a platen of the fixed-abrasive polishing station of the present invention;

[0023]FIG. 3 is a top view of an exemplary embodiment of a fixed-abrasive polishing pad of the present invention;

[0024]FIG. 4 is a top view of another exemplary embodiment of a fixed-abrasive polishing station of the present invention; and

[0025]FIG. 5 is a top view illustration of an exemplary embodiment of a CMP apparatus of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0026] The following description is of exemplary embodiments only and is not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth.

[0027] A schematic representation of an exemplary embodiment of a polishing station 10 of the present invention is shown in FIG. 1. Polishing station 10 includes a polishing platen 12 mounted for motion by a drive motor (not shown). A thick fixed-abrasive polishing pad 14 with a polishing surface 16 is mounted to polishing platen 12.

[0028] Fixed-abrasive polishing pad 14 has a generally homogenous composition with a suitably rigid constitution which permits pad 14 to have a thickness greater than 1 mm, preferably having a thickness in the range of from about 0.5 inches to 1.5 inches and more preferably having a thickness of about 1 inch. While pad 14 is relatively thick compared to prior art abrasive coated pads, it has a suitable hardness that enhances uniform planarization. The pad 14 is configured to have a relatively continuous wear rate throughout the life of the pad. Thus, as planarization proceeds, a fresh abrasive surface is continuously exposed to the wafer. Preferably, pad 14 has an average wear rate in the range of from less than 1 μm/min to about 10 μm/min as measured over the life of the pad. Thus, for a pad 14 having a thickness of 1 inch, 10,000 wafers or more could be planarized before the polishing pad would require replacement.

[0029] Fixed-abrasive polishing pad 14 may be formed from resin-bonded material with fixed abrasives uniformly distributed throughout. Fixed abrasives may include cerium oxide, aluminum oxide, silicon dioxide or any other abrasives suitable for planarizing a workpiece. Alternatively, fixed-abrasive polishing pad 14 may be formed from a ceramic-bonded material. The ceramic-bonded material may be of a soft porous type which may be strengthened by a stiffening agent such as melamine. Fixed abrasive polishing pad 14 may be of an open-cell or closed-cell structure and may be formed by suitable molding, firing and machining methods.

[0030] In addition, fixed-abrasive polishing pad 14 may exhibit friable behavior. As abrasive particles of friable materials dull, the coefficient of friction between the abrasive particles and the workpiece increase. At a critical point, the shear stresses at the points of contact will be greater than the bond strength of the abrasive particles to the pad. This will cause the more dull particles to break away from the pad, creating fresh, sharp points. With such a self-sharpening fixed abrasive polishing pad 14, the workpiece can be polished efficiently, with an increased polishing life compared to conventional pads.

[0031] During planarization, workpiece W is held by a workpiece carrier 18, which urges a workpiece W against fixed-abrasive polishing pad 14 with a desired amount of force. Workpiece W may be rotated by workpiece carrier 18 about an axis 20. Alternatively, workpiece carrier 18 may move workpiece W in an orbital pattern. Workpiece carrier 18 has a workpiece head 34. The purpose of workpiece head 34 is to help secure workpiece W to workpiece carrier 18 and also to prevent the workpiece from becoming dislodged during planarization. Any of a number of different types of workpiece heads can be used. For examples of suitable workpiece heads, see the following patents, incorporated herein by this reference: U.S. Pat. No. 6,056,632, issued May 2, 2000 to Mitchel et al.; U.S. Pat. No. 5,989,104, issued Nov. 23, 1999 to Kim et al.; U.S. Pat. No. 6,024,630, issued Feb. 15, 2000 to Shendon et al.; U.S. Pat. No. 5,762,544, issued Jun. 9, 1998 to Zuniga et al.; U.S. Pat. No. 6,080,050, issued Jun. 27, 2000 to Chen et al.; and U.S. Pat. No. 5,738,574, issued Apr. 14, 1998 to Tolles et al.

[0032] Workpiece carrier 18 may advance the workpiece toward polishing station 10 and apply pressure such that the workpiece engages the polishing surface 16 of the fixed-abrasive polishing pad 14 with a desired amount of force by a variety of mechanisms, for example, by expansion of a membrane assembly integral with the workpiece head 34, as more fully disclosed in U.S. Pat. No. 6,056,632. Workpiece carrier 18 also may be operatively connected to a pneumatic assembly (not shown) which moves a shaft 36 vertically, thus advancing the workpiece vertically down toward polishing pad 14 for polishing and moving the workpiece vertically up after polishing.

[0033] While workpiece carrier 18 urges workpiece W against polishing pad 14, polishing station 10 uses relative motion, preferably orbital motion, to polish workpiece W. In an exemplary embodiment, two rotatable shafts 22 and 24 are off-set from each other by the amount of a desired orbit. The radius of the orbit is preferably less than the radius of the workpiece W. Shaft 22 may rotate in the direction indicated by arrow A26 and shaft 24 may rotate at the same speed, but in the direction indicated by arrow A28. Eccentrics or cams (not shown) may be coupled to shaft 24 to allow polishing station 10 to also dither (in one or more axes as indicated by arrows A30 and A32). An example of polishing a workpiece by orbital motion is disclosed in U.S. Pat. No. 5,554,064, issued Sep. 10, 1996 to Breivogel et al., which patent is incorporated herein by reference. It is to be appreciated that a variety of other well-known means may be employed to facilitate the orbital motion of the polishing station 10 in the present invention. Alternatively, polishing station 10 may be rotated about a central axis by the drive motor.

[0034] An advantage of fixed-abrasive polishing pad 14 is that, as it wears, it continues to exhibit fresh mechanical and chemical abrasive qualities. Fixed-abrasive polishing pad 14 is also less susceptible to wear than conventional polishing pads. Accordingly, the wear rate and nonuniformity of wear is significantly less for pad 14 than for conventional polishing pads. Thus, pad 14 is able to uniformly planarize a greater number of workpieces than conventional pads. Increasing the thickness of fixed-abrasive polishing pad 14, preferably in the range of from about 0.5 inches to about 1.5 inches, and more preferably to about one inch, may further increase the number of workpieces that can be planarized before pad 14 needs to be replaced. To further maintain the uniform mechanical characteristics of pad 14, it may also be desirable to recondition surface 16 of pad 14, for example, by passing a diamond dressing plate over surface 16, as is know in the art.

[0035] To reduce heat generated by the planarization process and enhance uniformity of planarization, a fluid may be delivered to surface 16 of pad 14 by a manifold apparatus 38, as illustrated in FIGS. 1 and 2. The fluid may include any suitable liquid, such as deionized water, surfactants, lubricants or a slurry or a combination thereof. The fluid may be chemically treated to increase or decrease the mechanical action between pad 14 and the workpiece, such as to reduce wear of polishing pad 14 or reduce scratching of the workpiece. Alternatively, the pH and ionic composition may be suitably adjusted to enhance or reduce the chemical reaction between pad 14 and the workpiece. A pump 40 may distribute the fluid through a fluid line 52 and through distribution manifold 38 in the direction indicated by arrow A42 to one or more conduits 44 formed within platen 12. Conduits 44 allow for easy transportation of the fluid through platen 12. Fluid may then suitably flow from conduits 44 through one or more bores 48 in the direction of arrows A46. in contrast to conventional rotating polishing stations, an orbiting polishing station typically provides the advantage that fluid may be supplied through the polishing station to the polishing surface without the use of rotary unions or the like. However, it is to be appreciated that manifold apparatus 38 may be employed by a rotating polishing station utilizing the appropriate rotary unions, rotary couplings and the like.

[0036] Referring to FIGS. 1 and 3, fixed-abrasive polishing pad 14 similarly has one or more channels 50, which permit fluid to flow from bores 48 of platen 12 to the pad surface. Channels 50 may be molded into pad 14 when originally fabricated or may be machined into pad 14. Through bores 48 and channels 50, the fluid may flow from conduits 44 to the surface 16 of pad 14. In another embodiment, polishing pad 14 may have trenches 54, which extend between channels 50 on surface 16. The fluid may flow through the trenches 54 for even distribution below workpiece W.

[0037] In an alternative embodiment, fixed abrasive polishing pad may be of an open-cell structure having pores. Fluid may be delivered from manifold apparatus 38 to surface 16 of pad 14 through the pores of pad 14. Alternatively, fluid may be delivered to the polishing pad by way of a conventional conduit which delivers the fluid directly to the top surface of the polishing pad.

[0038] While polishing station 10 is illustrated in FIGS. 2 and 3 as round in shape, alternatively, polishing station 10 may be of any suitable shape, such as square or rectangular as shown in FIG. 4.

[0039] The fixed-abrasive polishing station of the present invention may be used in a variety of CMP apparatus. For example, the fixed-abrasive polishing pad of the present invention may be used in an integrated, multiple polishing station system, such as the Avantgaard™ 776, Momentum™ and Genesis™ CMP Systems by Speedfam-IPEC. Such multiple polishing station systems may have two or more polishing stations for performing CMP on workpieces. Referring to FIG. 5, a multiple polishing stations apparatus 100 is illustrated having four polishing stations 102, 104, 106, and 108, although it will be appreciated that multiple polishing stations apparatus 100 may have one, two or any other suitable number of polishing stations. Polishing stations 102, 104, 106 and 108 each may be fixed-abrasive polishing stations, according to the present invention, that are configured to move orbitally.

[0040] Fixed-abrasive polishing stations 102, 104, 106 and 108 are positioned within a base 110 having a top surface 112. Top surface 112 is configured with a number of openings 114 to correspond to the number of polishing stations employed by multiple polishing station apparatus 100. Openings 114 are large enough to permit the fixed abrasive polishing stations to orbit without interference from base 110. A workpiece handling robot 116 is centered between the polishing stations and is configured to transport a workpiece from a transfer station 118 to one of the polishing stations for polishing and back to the transfer station after polishing.

[0041] Multiple polishing stations apparatus 100 employs workpiece carriers (not shown), the number of which may correspond to the number of polishing stations. The workpiece carriers receive workpieces from the workpiece handling robot 116 and hold the workpieces and polish them by pressing them against the respective fixed-abrasive polishing stations 102, 104, 106 and 108. Each of the workpiece carriers aligns vertically with a corresponding polishing station and is attached to the end of a cylindrical shaft that is configured to rotate the workpiece carrier and the workpiece around a longitudinal axis of the shaft. In addition to rotation about the longitudinal axis, the workpiece carrier may be configured to translate radially or otherwise oscillate or dither. Alternatively, the workpiece carriers may be suitably configured to move orbitally so that during polishing the workpiece carrier and the fixed-abrasive polishing station both move orbitally, preferably in opposite directions.

[0042] During operation of multiple polishing station apparatus 100, robot 116 receives a workpiece W from transfer station 118. Robot 116 then positions workpiece W proximate to one of the polishing stations 102, 104, 106 or 108. A workpiece carrier aligned vertically about the respective polishing station receives a workpiece W from robot 116. The workpiece carrier then urges workpiece W against a fixed-abrasive polishing pad 120 of the fixed-abrasive polishing station. The workpiece carrier presses workpiece W against the fixed-abrasive polishing pad 120 as it rotates or, alternatively, orbits. The fixed-abrasive polishing station preferably orbits, as described above, to uniformly planarize and polish W, although it will be appreciated that the fixed-abrasive polishing station may rotate, as opposed to orbit, or move in a combined orbital and rotational manner.

[0043] After polishing of workpiece W, the workpiece carrier raises workpiece W above the fixed-abrasive polishing station. Robot 116 then moves into a suitable position to receive workpiece W from the workpiece carrier. Robot 116 then may transport workpiece W to a buffing station 122 for buffing of workpiece W. After buffing of workpiece W, robot 116 removes workpiece W from buffing station 122 and back to transfer station 118. After polishing, the fixed-abrasive polishing pad may be reconditioned. Alternatively, the fixed abrasive polishing pad may be reconditioned during polishing of the workpiece.

[0044] While multiple polishing station apparatus 100 is illustrated in FIG. 5 with all polishing stations 102, 104, 106 and 108 employing fixed-abrasive polishing stations, it will be appreciated that in an alternative embodiment only one of the multiple stations may employ a fixed-abrasive polishing station, with the other polishing stations employing any suitable polishing apparatus. For example, in one embodiment of the multiple polishing station 100, only one fixed-abrasive polishing station may be employed, while the other polishing stations employ conventional rotating polishing platens using conventional CMP polishing pads. Accordingly, workpiece W may be polished first at the fixed-abrasive polishing station and subsequently at a conventional CMP rotating or orbiting platen. In another embodiment, on orbital fixed-abrasive polishing station may be employed while the other fixed-abrasive polishing stations do not orbit.

[0045] Alternatively, the fixed abrasive polishing pad of the present invention may also be used in other multiple polishing station systems. For example, the fixed abrasive polishing pad of the present invention may be used in one or more polishing stations of a carousel-type CMP apparatus. For examples of carousel-type CMP apparatuses, see U.S. Pat. No. 5,804,507, issued Sep. 8, 1998 to Perlov et al. and U.S. Pat. No. 5,738,574, issued Apr. 14, 1998 to Tolles et al., which are incorporated herein by this reference.

[0046] Although the subject invention has been described herein in conjunction with the appended drawing Figures, it will be appreciated that the scope of the invention is not so limited. Various modifications in the arrangement of the components discussed and the steps described herein for using the subject device may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6910951Feb 24, 2003Jun 28, 2005Dow Global Technologies, Inc.The method improves ability to control the planarization process, increased uniformity of the planarized surface produced, reduced cost and increased throughput
US7066801Feb 21, 2003Jun 27, 2006Dow Global Technologies, Inc.Method of manufacturing a fixed abrasive material
US8128461 *Jun 16, 2008Mar 6, 2012Novellus Systems, Inc.Chemical mechanical polishing with multi-zone slurry delivery
US20100248601 *Aug 10, 2007Sep 30, 2010Mcgrogan DerekAbrasive articles
Classifications
U.S. Classification451/36, 451/41
International ClassificationB24D3/14, B24D3/28, B24B7/22
Cooperative ClassificationB24D3/28, B24D3/14, B24B7/228
European ClassificationB24D3/14, B24D3/28, B24B7/22E
Legal Events
DateCodeEventDescription
Dec 13, 2000ASAssignment
Owner name: SPEEDFAM-IPEC CORPORATION, ARIZONA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:FRUITMAN, CLINTON O.;DYER, TIMOTHY S.;REEL/FRAME:011366/0645
Effective date: 20001211