US20080014842A1 - Polishing head for polishing semiconductor wafers - Google Patents
Polishing head for polishing semiconductor wafers Download PDFInfo
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- US20080014842A1 US20080014842A1 US11/774,532 US77453207A US2008014842A1 US 20080014842 A1 US20080014842 A1 US 20080014842A1 US 77453207 A US77453207 A US 77453207A US 2008014842 A1 US2008014842 A1 US 2008014842A1
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- United States
- Prior art keywords
- annular
- flexible membrane
- outer flexible
- annular chamber
- base structure
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/27—Work carriers
- B24B37/30—Work carriers for single side lapping of plane surfaces
Abstract
A polishing head and method for chucking a semiconductor wafer onto the polishing head uses a base structure and an outer flexible membrane with at least a first annular chamber and a second annular chamber positioned between the base structure and the outer flexible membrane. The polishing head includes a central cavity positioned below the base structure and at least partly defined by the outer flexible membrane, which is used to hold the semiconductor wafer onto the outer flexible membrane.
Description
- This application is a continuation-in-part of application Ser. No. 11/680,588, filed Feb. 28, 2007, which is entitled to the benefit of U.S. Provisional Patent Application Ser. Nos. 60/778,675, filed on Mar. 3, 2006, 60/800,468, filed on May 15, 2006, 60/834,890, filed on Aug. 1, 2006, 60/837,109, filed on Aug. 11, 2006 and 60/844,737, filed on Sep. 15, 2006, which are all incorporated herein by reference.
- The invention relates generally to semiconductor processing equipments, and more particularly to a polishing head and method for handling and polishing semiconductor wafers.
- Local and global planarization of semiconductor wafers becomes increasingly important as more metal layers and interlayer dielectric layers are stacked on the wafers. A preferred method to planarize semiconductor wafers is the chemical mechanical polishing (CMP) method, where a surface of a semiconductor wafer is polished using a slurry solution supplied between the wafer and a polishing pad. The CMP method is also widely used for damascene process to form copper structures on the semiconductor wafers.
- In general, a CMP equipment includes a polishing table where a polishing pad is placed and a wafer carrier that supports a semiconductor wafer and presses the wafer against the polishing pad. The CMP equipment may also include a wafer cleaner to clean and dry the polished wafers.
- An important component of a CMP equipment is the polishing head that holds a semiconductor wafer to be polished on a polishing surface. The polishing head is designed to chuck (load) and de-chuck (unload) the wafer, and to apply pressure to the wafer onto the polishing surface. After a wafer is polished, a strong bond may exist between the wafer and the polishing surface, which makes chucking the wafer onto the polishing head challenging. The polishing head must be designed to overcome this bond between the wafer and the polishing surface to chuck the wafer onto the polishing head. During the wafer polishing, the polishing head must apply proper pressure to the wafer to minimize uneven polishing.
- In view of the above issues, what is needed is a polishing head and method for handling and polishing semiconductor wafers that overcomes these issues to properly handle and polish the wafers.
- A polishing head and method for chucking a semiconductor wafer onto the polishing head uses a base structure and an outer flexible membrane with at least a first annular chamber and a second annular chamber positioned between the base structure and the outer flexible membrane. The polishing head includes a central cavity positioned below the base structure and at least partly defined by the outer flexible membrane, which is used to hold the semiconductor wafer onto the outer flexible membrane.
- A polishing head in accordance with an embodiment of the invention comprises a base structure, an outer flexible membrane, a central cavity, a first fluid channel, a second fluid channel and a third fluid channel. The outer flexible membrane is positioned below the base structure such that at least a first annular chamber and a second annular chamber are positioned between the base structure and the outer flexible membrane. The second annular chamber is positioned to surround the first annular chamber. A lower surface of the outer flexible membrane is used to contact the semiconductor wafer. The central cavity is positioned below the base structure and at least partly defined by the outer flexible membrane. The central cavity is open at the lower surface of the outer flexible membrane. The first fluid channel is connected to the first annular chamber to supply pressurized fluid and to apply suction to the first chamber. The second fluid channel is connected to the second annular chamber to supply pressurized fluid to the second chamber. The third fluid channel is connected to the central cavity. The third fluid channel is used to apply suction directly to the semiconductor wafer through the central cavity to hold the semiconductor wafer onto the outer flexible membrane.
- A polishing head in accordance with another embodiment of the invention comprises a base structure, an outer flexible membrane, a central cavity, a first inner annular flexible membrane, a second inner annular flexible membrane, a first fluid channel, a second fluid channel, a third fluid channel and a fourth fluid channel. The outer flexible membrane is positioned below the base structure such that at least a first annular chamber and a second annular chamber are positioned between the base structure and the outer flexible membrane. The second annular chamber is positioned to surround the first annular chamber. A lower surface of the outer flexible membrane is used to contact the semiconductor wafer. The central cavity is positioned below the base structure and at least partly defined by the outer flexible membrane. The central cavity is open at the lower surface of the outer flexible membrane. The first inner annular flexible membrane is positioned between the base structure and the outer flexible membrane. The first inner annular flexible membrane and the base structure at least partly define the first annular chamber. The second inner annular flexible membrane is positioned between the base structure and the outer flexible membrane. The second inner annular flexible membrane and the base structure at least partly define the second annular chamber. The first fluid channel is connected to the first annular chamber to supply pressurized fluid to the first chamber. The second fluid channel is connected to the second annular chamber to supply pressurized fluid to the second chamber. The third fluid channel is connected to a space between the outer flexible membrane and the first and second inner annular flexible membranes. The third fluid channel is used to selectively apply suction to the space. The fourth fluid channel is connected to the central cavity. The fourth fluid channel is used to apply suction directly to the semiconductor wafer through the central cavity to hold the semiconductor wafer onto the outer flexible membrane.
- A method of chucking a semiconductor wafer onto a polishing head in accordance with an embodiment of the invention comprises positioning the semiconductor wafer against a lower surface of an outer flexible membrane of the polishing head, the outer flexible membrane being positioned below a base structure of the polishing head such that at least a first annular chamber and a second annular chamber are positioned between the base structure and the outer flexible membrane, the polishing head including a central cavity positioned below the base structure and at least partly defined by the outer flexible membrane, the central cavity being open at the lower surface of the outer flexible membrane, reducing the pressure in the first annular chamber to deflate the first annular chamber, and applying suction to the central cavity to chuck the semiconductor wafer onto the lower surface of the outer flexible membrane.
- Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrated by way of example of the principles of the invention.
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FIG. 1 is a vertical cross-sectional view of a polishing head in accordance with an embodiment of the present invention. -
FIG. 2 is a bottom view of the polishing head ofFIG. 1 with an outer flexible membrane being partially cut away to show first, second and third inner annular flexible membranes in accordance with an embodiment of the invention. -
FIG. 3A is a bottom view of a first annular disc of the polishing head ofFIG. 1 in accordance with an embodiment of the invention. -
FIG. 3B is a cross-sectional view of the first annular disc ofFIG. 3A . -
FIG. 4A is a perspective view of an inner annular flexible membrane of the polishing head ofFIG. 1 in accordance with an embodiment of the invention. -
FIG. 4B is a cross-sectional view of the inner annular flexible membrane ofFIG. 4A . -
FIG. 5 is a cross-sectional view of an annular disc and an inner annular flexible membrane in accordance with an embodiment of the invention. -
FIG. 6A is a cross-sectional view of an example of second and third annular discs with the second and third inner annular flexible membranes in accordance with an embodiment of the invention. -
FIG. 6B is a cross-sectional view of another example of the second and third annular discs with the second and third inner annular flexible membranes in accordance with an embodiment of the invention. -
FIG. 7A is a block diagram of a valve-and-regulator assembly of the polishing head ofFIG. 1 in accordance with an embodiment of the invention. -
FIG. 7B is a block diagram of the valve-and-regulator assembly of the polishing head ofFIG. 1 in accordance with an alternative embodiment of the invention. -
FIG. 8A is another vertical cross-sectional view of the polishing head ofFIG. 1 with a semiconductor wafer chucked onto the polishing head in accordance with an embodiment of the present invention. -
FIG. 8B is another vertical cross-sectional view of the polishing head ofFIG. 1 with a semiconductor wafer chucked onto the polishing head in accordance with another embodiment of the present invention. -
FIG. 9 is a bottom view of the first, second and third annular discs with interconnected recess regions in accordance with an embodiment of the invention. -
FIG. 10 is a bottom view of the outer flexible membrane that has conformed to the interconnected recess regions of the annular discs in accordance with an embodiment of the invention. -
FIG. 11A is a cross-sectional view showing a portion of the outer flexible membrane with an annular flap in accordance with an embodiment of the invention. -
FIG. 11B is a cross-sectional view showing the portion of the outer flexible membrane with the annular flap in accordance with an alternative embodiment of the invention. -
FIG. 12A is a vertical cross-sectional view of a polishing head in accordance with another embodiment of the present invention. -
FIG. 12B is another vertical cross-sectional view of the polishing head ofFIG. 12A with a semiconductor wafer chucked onto the polishing head in accordance with an embodiment of the present invention. -
FIG. 13A is a vertical cross-sectional view of a polishing head in accordance with another embodiment of the present invention. -
FIG. 13B is another vertical cross-sectional view of the polishing head ofFIG. 13A with a semiconductor wafer chucked onto the polishing head in accordance with an embodiment of the present invention. -
FIG. 14A is a vertical cross-sectional view of a polishing head in accordance with another embodiment of the present invention. -
FIG. 14B is another vertical cross-sectional view of the polishing head ofFIG. 14A with a semiconductor wafer chucked onto the polishing head in accordance with an embodiment of the present invention. -
FIG. 15 is a process flow diagram of a method of chucking a semiconductor wafer onto a polishing head in accordance with an embodiment of the invention. - With reference to
FIG. 1 , a polishinghead 10 for polishing a semiconductor wafer W according to an embodiment of the present invention is described.FIG. 1 is a vertical cross-sectional view of the polishinghead 10 after it is assembled. The polishinghead 10 is used to remove material from the wafer that is being polished. The polishinghead 10 is configured to hold the wafer and polish it by rotating and pressing the wafer on a polishingsurface 11. Abrasive slurry and/or chemical can be used during the polishing of the wafer. - The polishing
head 10 includes ahousing 12, abase 14 and aretainer ring 16. Thehousing 12 is connected to adrive shaft 18, which is used to move and rotate the polishinghead 10. Thedrive shaft 18 is connected to a motor (not shown) that rotates the drive shaft. Thedrive shaft 18 is also connected to a vertical drive mechanism (not shown), such as a pneumatic actuator, to displace the polishinghead 10 vertically toward the polishingsurface 11. Thebase 14 is connected to thehousing 12 via aflexure 20. - The
flexure 20 is a thin circular disc made of a flexible material. As an example, theflexure 20 can be a thin metal circular disc. However, theflexure 20 can be made of other flexible materials. The interior region of theflexure 20 is attached to thehousing 12 and the base 14 using joint screws, adhesive material or any other means to physically attach the flexure to the housing and the base. The outer edge of theflexure 20 is attached to theretainer ring 16 using joint screws, adhesive material or any other means to physically attach the flexure to the retainer ring. Theflexure 20 is configured to be reversibly flexible in a vertical manner. Theflexure 20 is further configured to bear shear stress applied to the flexure in a parallel manner to thebase 14. - The polishing
head 10 further includes anannular tube 22, which is positioned over theretainer ring 16 between thehousing 12 and theflexure 20. Theannular tube 22 is attached to thehousing 12 and theretainer ring 16 through theflexure 20. Theannular tube 22 is a sealed tube such that the interior region of the tube contains a fluid 24, such as air, water, oil, silicon, gelatin or other gas or liquid, at a predefined pressure. The fluid 24 may be a viscous material. - The
annular tube 22 is pressurized when a downward force is applied to the annular tube by thehousing 12 at a time when theretainer ring 16 is in contact with the polishingsurface 11. The pressurizedannular tube 22 transfers the downward force to theretainer ring 16. In an embodiment, theannular tube 22 is made of elastic material such that the tube is not subject to permanent deformation during repeated pressing processes of theretainer ring 16 against the polishingsurface 11. - When the
retainer ring 16 presses the polishingsurface 11, theannular tube 22 operates as a vibration absorber. The vibrations generated during a polishing process of the wafer W due to friction between the polishingsurface 11 and the bottom surface of theretainer ring 16 are absorbed by theannular tube 22. Therefore, the vibrations that are transferred to thehousing 12 of the polishinghead 10 can be minimized. - Since the pressure of the fluid 24 in the
annular tube 22 does not have to be controlled to adjust the pressure applied to the polishingsurface 11 through theretainer ring 16, theannular tube 22 does not have to be connected to any fluid source in the polishinghead 10. However, in other embodiments, theannular tube 22 can be connected to a fluid source in the polishinghead 10 such that the fluid 24 can be supplied to the tube or removed from the tube to control the volume of the fluid in the tube. - The polishing
head 10 further includes acontroller 26 and a valve-and-regulator assembly 28. In the illustrated embodiment, thecontroller 26 and the valve-and-regulator assembly 28 are situated within thehousing 12 above thebase 14. However, in other embodiments, thecontroller 26 and/or the valve-and-regulator assembly 28 may be situated external to the polishinghead 10. Thecontroller 26 is configured to control the components of the valve-and-regulator assembly 28, as described below. Thecontroller 26 is connected to an external controller (not shown), which may be a computer system, viawires 30 for power and data communication. Thecontroller 26 is also connected to the valve-and-regulator assembly 28 viawires 32 for power and data communication. The valve-and-regulator assembly 28 is connected tofluid channels 36A-36D. Thefluid channel 36A is used to receive pressurized gas, such as air. Thefluid channel 36B is used as an exhaust to release excess gas. Thefluid channel 36C is used to provide vacuum or suction. Thefluid channel 36D is used to receive deionized (D.I.) water. The valve-and-regulator assembly 28 is also connected to a number offluid channels 34A-34E, which are described below. - The polishing
head 10 also includes a firstannular disc 40A, a secondannular disc 40B, a thirdannular disc 40C, a first inner annularflexible membrane 42A, a second inner annularflexible membrane 42B, a third inner annularflexible membrane 42C and an outerflexible membrane 44. The first, second and thirdannular discs 40A-40C are attached to the base 14 using joint screws, adhesive material or any other means to physically attach the annular discs to the base. The first, second and thirdannular discs 40A-40C are positioned within the confines of theretainer ring 16. Thebase 14 and theannular discs 40A-40C form a base structure of the polishinghead 10. - The first
annular disc 40A is shown in more detail inFIGS. 3A and 3B .FIG. 3A is a bottom view of the firstannular disc 40A, whileFIG. 3B is a cross-sectional view of the first annular disc. As shown inFIGS. 3A and 3B , the firstannular disc 40A includes acircular hole 302 at its center and acircular recess region 304 on its bottom surface. Thecircular recess region 304 is positioned about thecircular hole 302 such that the circular hole is positioned at the center of thecircular recess region 304. Some of the advantages of the configuration of the firstannular disc 40A are described below. - Turning back to
FIG. 1 , the inner and outer diameters of the first, second and thirdannular discs 40A-40C at their bottom surfaces are determined such that the thirdannular disc 40C surrounds the secondannular disc 40B, and the secondannular disc 40B surrounds the firstannular disc 40A. In an embodiment, the outer edge of the secondannular disc 40B is configured to have a step and the inner edge of the thirdannular disc 40C is configured to have an inverted step. Thus, the outer edge of the secondannular disc 40B and the inner edge of the thirdannular disc 40C can be fitted together to interlock the second and third annular discs. Some of the advantages of the configuration of the second and thirdannular discs - The first inner annular
flexible membrane 42A is connected to the firstannular disc 40A such that a firstannular chamber 46A is defined by the firstannular disc 40A and the first inner annularflexible membrane 42A. The second inner annularflexible membrane 42B is connected to the secondannular disc 40B such that a secondannular chamber 46B is defined by the secondannular disc 40B and the second inner annularflexible membrane 42B. The third inner annularflexible membrane 42C is connected to the thirdannular disc 40C such that a thirdannular chamber 46C is defined by the thirdannular disc 40C and the third inner annularflexible membrane 42C. The first, second and third inner annularflexible membranes 42A-42C can be bonded to their respectiveannular discs 40A-40C using adhesive material. When one or more of the inner annularflexible membranes 42A-42C need to be changed, the respectiveannular discs - An example of an inner annular
flexible membrane 400 is illustrated inFIGS. 4A and 4B . As shown inFIGS. 4A and 4B , the inner annularflexible membrane 400 includes an innercircular sidewall 402 with a circulartop flap 404 that extends outward away from the center of the membrane. The inner annularflexible membrane 400 also includes an outercircular sidewall 408 with a circulartop flap 410 that extends inward toward the center of the membrane. The circulartop flaps flexible membrane 400 to the respectiveannular disc circular sidewall 402 defines acircular aperture 406 at the center of the inner annularflexible membrane 400. The size of theaperture 406 corresponds to the inner diameter D1 of the inner annularflexible membrane 400. The outercircular sidewall 408 defines the outer diameter D2 of the inner annularflexible membrane 400. The inner and outer diameters D1 and D2 of the inner annularflexible membrane 400 depend on whether the inner annular flexible membrane is to be used as the firstflexible membrane 42A, the secondflexible membrane 42B or the thirdflexible membrane 42C of the polishinghead 10. - Even though the polishing
head 10 is illustrated and described as comprising the threeannular chambers 46A-46C associated with their respectiveannular discs 40A-40C, the polishinghead 10 can be configured to comprise other number of annular chambers associated with their respective annular discs in other embodiments. - Turning back to
FIG. 1 , the outerflexible membrane 44 is attached to the base 14 such that the outer flexible membrane covers the first, second and third inner annularflexible membranes flexible membrane 44 is configured to include acircular recess region 48 at its center that conforms to the center circular hole of the firstannular disc 40A. Thecircular recess region 48 of the outerflexible membrane 44 forms a circularcentral cavity 50, which is open at the lower surface of the outer flexible membrane. The center of the outerflexible membrane 44 is attached to the base 14 using an adhesive material, one or more joint screws or any other means to physically attach the outer flexible membrane to the base. The outer annular edge of the outerflexible membrane 44, which extends inward, is attached to the bottom outer edge of the base 14 using one or more joint screws, an adhesive material or any other means to physically attach the outer annular edge of the outer flexible membrane to the base, as illustrated inFIG. 1 . Alternatively, the outer annular edge of the outerflexible membrane 44 may be attached to the upper outer edge of the thirdannular disc 40C using one or more joint screws, an adhesive material or any other means for fastening. The outerflexible membrane 44 and theannular discs 40A-40C define a large annular chamber, which contains theannular chambers 46A-46C created by the inner annularflexible membranes 42A-42C. - The outer
flexible membrane 44 is configured to have anannular periphery portion 54 and an annularcentral portion 56. Theannular periphery portion 54 is shaped to have an annular upside down U-shape such that the annular periphery portion is situated between the base 14 and theretainer ring 16. The annularcentral portion 56 of the outerflexible membrane 44 is also shaped to have an annular upside down U-shape such that the top of the upside downU-shaped portion 56 faces anannular recess 58 that is formed near the center of thebase 14. The upside downU-shaped portions U-shaped portions flexible membrane 44 allow the outerflexible membrane 44 to expand downward toward the wafer W and to contract upward away from the wafer without having to stretch or without having to stretch significantly. Thus, the outerflexible membrane 44 can be made of inelastic material and still function properly, i.e., expand and contract. However, in some embodiments, the outerflexible membrane 44 can still be made of elastic material. - The bottom surface of the outer
flexible membrane 44 is used as the surface that contacts the wafer W. The outerflexible membrane 44 and the first, second and third inner annularflexible membranes 42A-42C can be made of any flexible materials including rubbers and plastic materials. In some embodiments, plastic material such as PVC, Polystyrene, Nylon, and Polyethylene is used for the first, second and third inner annularflexible membranes 42A-42C. In some embodiments, elastic material such as rubber, elastomer, silicon rubber, and polyurethane rubber is used for the outerflexible membrane 44. In other embodiments, non-elastic material is used for the outerflexible membrane 44. - In some embodiments, the thicknesses of the first, second and third inner annular
flexible membranes 42A-42C are substantially thinner than the thickness of the outerflexible membrane 44. By using thin flexible membranes for the first, second and third inner annularflexible membranes 42A-42C, any pressure differential at the boundaries of the innerflexible membranes 42A-42C on the outerflexible membrane 44 and the wafer W by the first, second and third inner annularflexible membranes 42A-42C is minimized. As an example, the first, second and third inner annularflexible membranes 42A-42C can be films with thicknesses less than 0.2 mm. In this example, the outerflexible membrane 44 can be a film with a thickness greater than 0.5 mm. As another example, the first, second and third inner annularflexible membranes 42A-42C can be films with thicknesses between 0.06 mm and 0.09 mm. In this example, the outerflexible membrane 44 can be a film with a thickness between 0.6 and 0.9 mm. - The outer
flexible membrane 44 and the first, second and third inner annularflexible membranes 42A-42C are shown inFIG. 2 , which is a bottom view of the polishinghead 10 with the outer flexible membrane being partially cut away to show the first, second and third inner annular flexible membranes. As illustrated inFIG. 2 , D1, D2 and D3 are widths of the first, second and third inner annularflexible membranes 42A-42C, respectively, and thus, the widths of theannular chambers 46A-46C, respectively, which are defined by the first, second and third inner annularflexible membranes 42A-42C. These widths D1, D2 and D3 also correspond to the widths of the first, second and thirdannular discs 40A-40C, respectively. Thus, by adjusting the widths D1, D2 and D3 of thediscs 40A-40C, the widths of theannular chambers 46A-46C associated with the respective discs can be adjusted. - Turning back to
FIG. 1 , the firstannular disc 40A and the base 14 comprise at least onefluid channel 34A such that the firstannular chamber 46A is connected to the valve-and-regulator assembly 28 via thefluid channel 34A to receive pressurized gas. The secondannular disc 40B and the base 14 comprise at least onefluid channel 34B such that the secondannular chamber 46B is connected to the valve-and-regulator assembly 28 via thefluid channel 34B to receive pressurized gas. The thirdannular disc 40C and the base 14 comprise at least onefluid channel 34C such that the thirdannular chamber 46C is connected to the valve-and-regulator assembly 28 via thefluid channel 34C to receive pressurized gas. The pressurized gas may include air, nitrogen or a combination of different gases. The valve-and-regulator assembly 28 controls the pressure of the gas such that gas having different pressures can be supplied to the first, second and thirdannular chambers 46A-46C through therespective fluid channels 34A-34C. - The base 14 also comprises a
central fluid channel 34D, which connects thecentral cavity 50 to the valve-and-regulator assembly 28 through the outerflexible membrane 44 to apply a vacuum/suction and to provide D1 water to thecentral cavity 50. Thefluid channel 34D includes anopening 35, which is located at the center of the outerflexible membrane 44, and extends through outer flexible membrane. The base 14 further comprises at least onefluid channel 34E, which connects aspace 60 between the outerflexible membrane 44 and the inner annularflexible membranes 42A-42C to the valve-and-regulator assembly 28 to apply a vacuum/suction to thespace 60. Thefluid channel 34E allows a vacuum/suction to be applied to thespace 60 so that theannular chambers 46A-46C can be efficiently deflated when needed. - In an embodiment, at least some of the inner annular
flexible membranes 42A-42C are configured to include annular wrinkled portions to allow the membranes to expand and contract without having to stretch or without having to stretch significantly.FIG. 5 shows a cross-section of an inner annularflexible membrane 500 attached to anannular disc 502. Themembrane 500 is configured to include an annularwrinkled portion 504 on aninner sidewall 506 of the membrane and an annularwrinkled portion 508 on anouter sidewall 510 of the membrane. Thewrinkled portion 504 on theinner sidewall 506 is configured to protrude outward toward theouter sidewall 510 or toward theannular disc 502. Thewrinkled portion 508 on theouter sidewall 510 is configured to protrude inward toward theinner sidewall 506 or toward theannular disc 502. Thus, thewrinkled portions annular disc 502. In this embodiment, thewrinkled portion 504 of themembrane 500 faces anannular recess 512 that is formed at an inner side of theannular disc 502. Thewrinkled portion 508 of themembrane 500 faces anannular recess 514 that is formed at an outer side of theannular disc 502. Thewrinkled portions annular membrane 500 serve a similar function as the upside downU-shaped portions flexible membrane 44. Thewrinkled portions annular membrane 500 allow themembrane 500 to expand downward toward the wafer W (not shown inFIG. 5 ) and to contract upward away from the wafer without having to stretch or without having to stretch significantly. Thus, the inner annularflexible membrane 500 can be made of inelastic material and still function properly, i.e., expand and contract. However, in some embodiments, the inner annularflexible membrane 500 can still be made of elastic material. - Turning now to
FIGS. 6A and 6B , an example of adjusting the widths of the second and thirdannular chambers annular discs FIG. 6A shows a first set of the second and thirdannular discs joint screw 600.FIG. 6B shows a second set of the second and thirdannular discs joint screw 600. InFIG. 6A , the width D2 of the secondannular disc 40B is 13 mm and the width D3 of the thirdannular disc 40C is 7 mm. InFIG. 6B , the width D2 of the secondannular disc 40B has been changed to 17 mm and the width D3 of the thirdannular disc 40C has been changed to 3 mm. Consequently, the widths of the second and thirdannular chambers annular discs annular chambers annular discs flexible membranes annular disc 40A and the inner annularflexible membrane 42A do not have to be changed to adjust the widths of the second and thirdannular chambers - Turning now to
FIG. 7A , the components of the valve-and-regulator assembly 28 in accordance with an embodiment of the invention are shown. The valve-and-regulator assembly 28 includesmanifolds pressure regulators way valve 706 and awater trap 708. The manifold 702A is connected to thefluid channel 36A to receive pressurized gas. The manifold 702A is also connected to thepressure regulators fluid channel 36A to the pressure regulators. Thepressure regulators annular chambers fluid channels pressure regulators fluid channel 36B. Thepressure regulator 704A is configured to selectively direct pressurized gas to the firstannular chamber 46A. The pressure regular 704A is also configured to selectively release pressurized gas through thefluid channel 36B via the manifold 702B. Thus, thepressure regulator 704A can control the pressure within the firstannular chamber 46A. Similarly, thepressure regulators annular chambers pressure regulators 704A-704C are connected to thecontroller 26 via the wires 32 (shown inFIG. 1 ) to receive power and control signals. - The manifold 702C is connected to the
fluid channel 36C, which provides a vacuum/suction. The manifold 702C is also connected to thespace 60 between the outerflexible membrane 44 and the inner annularflexible membranes 42A-42C via thefluid channel 34E to apply a vacuum/suction to thespace 60. Thespace 60 may also be connected the manifold 702B such that thespace 60 can be connected to thefluid channel 36B. When the valve-and-regulator assembly 28 needs to selectively deflate theannular chambers annular chambers respective pressure regulators space 60 through the manifold 702C such that the outerflexible membrane 44 can move upward by the suction and deflate further theannular chambers central cavity 50 via thefluid channel 34D through thevalve 706 and thewater trap 708 to apply a vacuum/suction to thecavity 50. The three-way valve 706 is connected to the manifold 702C and thecentral cavity 50 via thewater trap 708. The three-way valve 706 is also connected to thefluid channel 36D to receive D.I. water. Thus, thevalve 706 can selectively provide D.I. water to thecentral cavity 50 or apply a vacuum/suction to thecentral cavity 50. Although not illustrated, the three-way valve 706 is connected to thecontroller 26 via the wires 32 (shown inFIG. 1 ) to receive power and control signals. Thewater trap 708 is connected to thefluid channel 34D to trap contaminated water from thecentral cavity 50 when a vacuum/suction is being applied to thecentral cavity 50. The contaminated water in thewater trap 708 can be released through thecentral cavity 50 by D.I. water received through thefluid channel 36D during an appropriate period. - Turning now to
FIG. 7B , the components of the valve-and-regulator assembly 28 in accordance with an alternative embodiment of the invention are shown. In this alternative embodiment, the valve-and-regulator assembly 28 further includes three-way valves way valve 710A is connected to thepressure regulator 704A, the manifold 702C and the firstannular chamber 46A. Since the manifold 702C is connected to thefluid channel 36C, which provides a vacuum/suction, the three-way valve 710A is able to selectively connect theannular chamber 46A to the manifold 702C to apply suction to the firstannular chamber 46A to deflate theannular chamber 46A. The three-way valve 710B is similarly connected to thepressure regulator 704B, the manifold 702C and the secondannular chamber 46B, and the three-way valve 710C is similarly connected to thepressure regulator 704C, the manifold 702C and the thirdannular chamber 46C. Thus, the three-way valve 710B is able to selectively connect the secondannular chamber 46B to the manifold 702C to apply suction to the second annular chamber to deflate the second annular chamber. Similarly, the three-way valve 710C is able to selectively connect the thirdannular chamber 46C to the manifold 702C to apply suction to the third annular chamber to deflate the third annular chamber. When the valve-and-regulator assembly 28 needs to selectively deflate theannular chambers way valves - With reference to
FIGS. 1 and 8 A, processes of chucking (loading) the wafer W onto the polishinghead 10, polishing the wafer on the polishingsurface 11 using the polishing head and de-chucking (unloading) the wafer from the polishing head in accordance with an embodiment of the invention are described.FIG. 8A shows a vertical cross-section of the polishinghead 10, which has the wafer W chucked onto it. InFIG. 1 , the outerflexible membrane 44 of thewafer carrier 10 is in contact with the back surface of wafer W. - In order to chuck the wafer W onto the polishing
head 10, suction is applied to thecentral cavity 50 via thefluid channel 34D. The inner annularflexible membranes 42A-42C may be open to the manifold 702B of the valve-regulator assembly 28 via their respectivefluid channels 34A-34C to reduce the pressures in theannular chambers 46A-46C, as described above with reference toFIG. 7A . As a result, gas in theannular chambers 46A-46C is released (evacuated) and theannular chambers 46A-46C are deflated, as illustrated inFIG. 8A . Alternatively, suction is applied directly to theannular chambers 46A-46C via therespective fluid channels 34A-34C through their respective three-way valves regulator assembly 28 to evacuate the gas in the annular chambers (reducing the pressures in theannular chambers 46A-46C) and deflate the annular chambers. Suction can also be applied to thespace 60 between the inner annularflexible membranes 42A-42C and the outerflexible membrane 44 via thefluid channel 34E to further assist in deflating theannular chambers 46A-46C. - As the
annular chambers 46A-46C are deflated, the inner annularflexible membrane 42A and the outerflexible membrane 44 are sucked into thecircular recess region 304 of the firstannular disc 40A, forming a large circular depression on the bottom surface of the outer flexible membrane that conforms to thecircular recess region 304. In effect, the circular depression formed on the bottom surface of the outerflexible membrane 44 increases the size or diameter of thecentral cavity 50. As a result of the suction, a vacuum is created in thecentral cavity 50 between the outerflexible membrane 44 and the back surface of the wafer W, which causes the wafer to be chucked onto the polishinghead 10. Thecircular recess region 304 of the firstannular disc 40A allows more area of the wafer W to be subjected to the suction, which increase chucking power of the polishing head. Thecircular recess region 304 allows the polishinghead 10 to have a smallercentral cavity 50. As an example, the diameter of thecentral cavity 50 may be less than 5 mm, e.g., 2.5 mm. In a conventional polishing head, the diameter of a similar central cavity is typically much greater than 5 mm, e.g., 10 mm, so that the suction created in the central cavity has enough suction power to chuck a semiconductor wafer. Since the diameter of the central cavity is relatively large, the conventional polishing head may need to provide pressure in the central cavity during a wafer polishing process to provide sufficient downward force to the zone of a semiconductor wafer below the central cavity. However, such pressure in thecentral cavity 50 of the polishinghead 10 is not necessary since thecentral cavity 50 is sufficiently small. - In order to polish the wafer W on the polishing
surface 11, the polishinghead 10 with the chucked wafer is moved over the polishing surface. The polishinghead 10 is then lowered onto the polishingsurface 11 such that theretainer ring 16 contacts the polishing surface. Next, the first, second and thirdannular chambers 46A-46C are inflated by supplying pressurized gas with same or different pressures to theannular chambers 46A-46C through thepressure regulators 704A-704C, respectively, of the valve-and-regulator assembly 28. As a result, theannular chambers 46A-46C are inflated, which push the bottom surface of the outerflexible membrane 44 toward the polishingsurface 11, and thus, applies same or different pressures to the wafer on the polishingsurface 11 during the polishing process. - In this manner, the pressures applied to the wafer W can be controlled in terms of zones of the wafer. The pressure applied to a central zone that is under the first
annular chamber 46A is controlled by the pressure in that chamber. The pressure applied to an intermediate annular zone surrounding the central zone that is under the secondannular chamber 46B is controlled by that chamber. The pressure applied to an outer annular zone surrounding the intermediate annular zone that is under the thirdannular chamber 46C is controlled by that chamber. By applying different pressures to the respective zones, polishing rates at the respective zones can be controlled individually. - As the bottom surface of the outer
flexible membrane 44 is pushed downward, the shapes of the annular upside downU-shaped portions flexible membrane 44 are changed such that the heights of these upside down U-shaped portions are decreased. That is, the annular upside downU-shaped portions flexible membrane 44 are at least partially straightened. These changes in shape of the annular upside downU-shaped portions flexible membrane 44 to move downward more easily. Without the upside downU-shaped portions flexible membrane 44 need to be elongated or stretched, which would not allow the bottom surface of the outerflexible membrane 44 to move downward easily. - During the polishing process, the suction applied to the
central cavity 50 may be removed. Alternatively, instead of removing the suction applied to thecentral cavity 50 during the polishing process, the applied suction can be used to detect wafer slippage. If the wafer W is slipped out from the polishinghead 10 during the polishing process, the pressure of the suction will be changed. By detecting this pressure change, the wafer slippage can be detected. - After the polishing process is finished, the suction is again applied to the
central cavity 50 in order to hold the wafer W. After the wafer is held by the suction onto the outerflexible membrane 44, the pressurized gas is no longer applied to the first, second and thirdannular chambers 46A-46C. In addition, another suction is applied to thespace 60 between the inner annularflexible membranes 42A-42C and the outerflexible membrane 44 to deflate theannular chambers 46A-46C, which raises the bottom surface of theouter membrane 44 toward thebase 14. In order to assist in raising the bottom surface of theouter membrane 44, theannular chambers 46A-46C can be opened to the manifold 702B through theirrespective pressure regulators 704A-704C, or opened to the manifold 702C through their respective three-way valves 710A-710C, as described above with reference toFIG. 7A andFIG. 7B , respectively. Since the suction applied to thecentral cavity 50 attracts the wafer toward thebase 14, the wafer is lifted from the polishingsurface 11 and moved toward the base 14 as theannular chambers 46A-46C are deflated. - As the bottom surface of the outer
flexible membrane 44 is moved upward, the shapes of the annular upside downU-shaped portions - Next, the polishing
head 10 is transferred to a wafer unload station (not shown) and then the wafer is unloaded or de-chucked to the wafer unload station. In order to de-chuck the wafer from the polishinghead 10, the suction is no longer applied to thecentral cavity 50 and thespace 60 between the inner annularflexible membranes 42A-42C and the outerflexible membrane 44. Furthermore, pressurized gas is applied to at least one of the inner annularflexible membranes 42A-42C through therespective fluid channels 34A-34C in order to unload the wafer onto the wafer unload station. Alternatively, D.I. water can be applied to the wafer through thecentral cavity 50 via thefluid channel 34D in order to unload the wafer onto the wafer unload station. - With reference to
FIG. 8B , an alternative process of chucking the wafer W onto the polishinghead 10 is described. In this alternative chucking process, theannular chambers head 10, suction is applied to thecentral cavity 50 via thefluid channel 34D. The second and thirdannular chambers annular chambers pressure regulators regulator assembly 28. However, the inner annularflexible membrane 42A may be opened to the manifold 702B of the valve-regulator assembly 28 via thefluid channel 34A, as described above with reference toFIG. 7A . As a result, gas in theannular chamber 46A is released (evacuated) and theannular chamber 46A is deflated, as illustrated inFIG. 8B . Alternatively, suction is applied directly to theannular chamber 46A via thefluid channel 34A through the three-way valve 710A and the manifold 702C of the valve-regulator assembly 28 to evacuate the gas in theannular chamber 46A and deflate theannular chamber 46A. Suction can also be applied to thespace 60 between the inner annularflexible membranes 42A-42C and the outerflexible membrane 44 via thefluid channel 34E to further assist in deflating theannular chamber 46A. - As the
annular chamber 46A is deflated, the inner annularflexible membrane 42A and the outerflexible membrane 44 are sucked into thecircular recess region 304 of the firstannular disc 40A, forming a large circular depression on the bottom surface of the outer flexible membrane that conforms to the firstannular disc 40A. However, theannular chambers flexible membrane 44 when suction is being applied to thecentral cavity 50 via thefluid channel 34D. - Turning now to
FIG. 9 , the first, second and thirdannular discs 40A-40C in accordance with another embodiment of the invention are shown. In this embodiment, at least some of theannular discs 40A-40C are configured to includeinterconnected recess regions 900A-900D. Theinterconnected recess regions 900A-900D of the first, second and thirdannular discs 40A-40C are similar to therecess region 304 of the firstannular disc 40A, which is illustrated inFIGS. 3A and 3B . Theinterconnected recess regions 900A-900D of the first, second and thirdannular discs 40A-40C allow the outerflexible membrane 44, as well as the inner annularflexible membranes 42A-42C, to conform to theinterconnected recess regions 900A-900D when the inner annularflexible membranes 42A-42C are deflated and suction is applied to one or more of theannular chambers 46A-46C and/or thespace 60 between the inner annular flexible membranes 42-42C and the outerflexible membrane 44. - As illustrated in
FIG. 10 , when the outerflexible membrane 44 is conformed to the interconnected recess regions 900 due to the applied suction, the lower surface of the outerflexible membrane 44 forms interconnecteddepressions 1002A-1002D, which allow a vacuum to be created in theinterconnected depressions 1002A-1002D through theopening 35 of thefluid channel 34D when a wafer is in contact with the outer flexible membrane. Since theinterconnected recess regions 900A-900D are distributed throughout theannular discs 40A-40C, the corresponding interconnected depressions are also distributed throughout the lower surface of the outerflexible membrane 44. Thus, when a wafer is in contact with the lower surface of the outerflexible membrane 44 and suction is applied to theinterconnected depressions 1002A-1002D, a vacuum can be created and applied over most of the back surface of the wafer. In effect, the vacuum in theinterconnected depressions 1002A-1002D creates a bond between the wafer and the outerflexible membrane 44 over a large area of the wafer that corresponds to the area of theinterconnected depressions 1002A-1002D. - In
FIG. 9 , theinterconnected recess regions 900A-900D include acircular recess region 900A andannular recess regions annular disc 40A. In addition, theinterconnected recess regions 900A-900D include anannular recess regions 900D, which is located on the bottom surface of theannular disc 40B. In this illustrated embodiment, there are no recess regions on the bottom surface of theannular disc 40C. However, in other embodiments, theannular disc 40C may include one or more interconnected recess regions. - In other embodiments, one or more of the
annular discs 40A-40C may have interconnected recess regions having different configurations than theinterconnected recess regions 900A-900D. As an example, one or more of theannular discs 40A-40C may have interconnected recess regions that extend in a radial direction. As another example, one or more of theannular discs 40A-40C may have interconnected recess regions that are geometrical in shape. - The operation of a polishing head with the
annular discs 40A-40C ofFIG. 9 is similar to the operation of the polishinghead 10 ofFIG. 1 . Thus, the chucking process, the polishing process and the de-chucking process using the polishing head with theannular discs 40A-40C ofFIG. 9 are similar to the corresponding processes using the polishinghead 10 ofFIG. 1 . - A concern with the polishing
head 10 using theannular discs 40A-40C ofFIG. 1 orFIG. 9 is that the thirdannular chamber 46C defined by the third inner annularflexible membrane 42C may over inflate when the pressure in the thirdannular chamber 46C is significantly higher than the pressure in the secondannular chamber 46B. As a result, the thickness of the thirdannular chamber 46C may be greater than the desired thickness D3, which is illustrated inFIG. 2 . - Turning now to
FIG. 11A , a portion of the outerflexible membrane 44 in accordance with an embodiment of the invention is shown. In this embodiment, the outerflexible membrane 44 includes anannular flap 45 that extends upward toward thebase 14. Theannular flap 45 is attached to theupper surface 47 of thelower portion 49 of the outerflexible membrane 44 such that the annular flap is positioned between adjacent sidewalls of the second and third inner annularflexible membranes annular flap 45 provides a barrier between the secondannular chamber 46B produced by the second inner annularflexible membrane 42B and the thirdannular chamber 46C produced by the third inner annularflexible membrane 42C so that the third annular chamber does not over inflate into the region below the lower surface of the secondannular disc 40B for the second annular chamber. Thus, theannular flap 45 of the outerflexible membrane 44 serves to maintain the thickness D3 of the thirdannular chamber 46C even when the pressure in the third annular chamber is significantly higher than the pressure in the secondannular chamber 46B, which allows the polishinghead 10 to control the zone of the wafer that is affected by the third annular chamber during polishing. In the embodiment shown inFIG. 11A , theannular flap 45 is an integral part of the outerflexible membrane 44. That is, the outerflexible membrane 44 with theannular flap 45 is made of a single piece of material. Thus, in this embodiment, theannular flap 45 is made of the same material as the rest of the outerflexible membrane 44. - In an alternative embodiment, the
annular flap 45 of the outerflexible membrane 44 may be a separate piece that is attached tobottom portion 49 of the outer flexible membrane, as illustrated inFIG. 11B . In this embodiment, thebottom portion 49 of the outerflexible membrane 44 includes anannular groove 51 on itsupper surface 47. Theannular flap 45 is situated in theannular groove 51 of thebottom portion 49 of the outerflexible membrane 44. Theannular flap 45 may be attached to thebottom portion 49 of the outerflexible membrane 44 using an adhesive material. In this embodiment, theannular flap 45 can be made of a material that is different than the rest of the outerflexible membrane 44. As an example, theannular flap 45 can be made of a material that is harder than the material for the rest of the outerflexible membrane 44 to provide a stronger barrier between the secondannular chamber 46B and the thirdannular chamber 46C. - Turning now to
FIG. 12A , a polishinghead 10A for polishing a semiconductor wafer W according to another embodiment of the present invention is shown. The polishinghead 10A is similar to the polishinghead 10 ofFIG. 1 and includes most of the elements of the polishinghead 10. Thus, inFIG. 12A , the reference numbers ofFIG. 1 are used to indicate these common elements. A difference between the polishinghead 10A and the polishinghead 10 is that the polishinghead 10A includes a firstannular disc 40A′, which has acentral cavity 50′ but does not have a circular recess region, such as thecircular recess region 304 of the firstannular disc 40A of the polishinghead 10. Thus, the bottom surface of the firstannular disc 40A′ is substantially flat. In an embodiment, the firstannular disc 40A′ of the polishinghead 10A is configured such that its thickness, or vertical width, is similar to that of the secondannular disc 40B and the thirdannular disc 40C. Thus, the bottom surfaces of the first, second and thirdannular discs 40A′, 40B and 40C are substantially planar or flat. - The polishing
head 10A operates in a manner similar to that of the polishinghead 10 with respect to the processes of chucking the wafer W onto the polishinghead 10A, polishing the wafer on the polishingsurface 11 using the polishinghead 10A and de-chucking the wafer from the polishinghead 10A in accordance with an embodiment of the invention. However, since the lower surface of the firstannular disc 40A′ of the polishinghead 10A does not have a circular recess region, only a small circular depression that conforms to thecentral cavity 50′ of the firstannular disc 40A′ will be formed when a semiconductor wafer is chucked onto the polishinghead 10A with all theannular chambers 46A-46C deflated. In an embodiment, when chucking a wafer, theannular chambers annular chamber 46A is deflated, as illustrated inFIG. 12B . This process is similar to the process described above with reference toFIG. 8B . The deflation of theannular chamber 46A with the inflation of theannular chambers circular depression 304′ on the bottom surface of the outerflexible membrane 44 that conforms to the firstannular disc 40A′, as illustrated inFIG. 12B . In effect, thecircular depression 304′ formed on the bottom surface of the outerflexible membrane 44 increases the size or diameter of thecentral cavity 50′. With suction being applied to thecentral cavity 50′ via thefluid channel 34D, a vacuum is created in thecircular depression 304′, which chucks the semiconductor wafer onto the polishinghead 10A. Thecircular depression 304′ formed by the deflation of theannular chamber 46A and the inflation of theannular chambers head 10A. - Turning now to
FIG. 13A , a polishinghead 10B for polishing a semiconductor wafer W according to another embodiment of the present invention is shown. The polishinghead 10B is similar to the polishinghead 10 ofFIG. 1 and includes most of the elements of the polishinghead 10. Thus, inFIG. 13A , the reference numbers ofFIG. 1 are used to indicate these common elements. One of differences between the polishinghead 10B and the polishinghead 10 is that the polishinghead 10B does not include any annular discs attached to thebase 14. - Another difference is that the polishing
head 10B also does not include any inner flexible membranes that form annular chambers. Rather, the polishinghead 10B includes an outerflexible membrane 44′ that is configured to formannular chambers 46A′, 46B′ and 46C′, which are similar to theannular chambers head 10. - In an embodiment, the outer
flexible membrane 44′ is similar in construction to the outerflexible membrane 44 of the polishinghead 10. Thus, the outerflexible membrane 44′ includes acircular recess region 48′, which forms acentral cavity 50″, and annular upside downU-shaped portions 54′ and 56′. However, the outerflexible membrane 44′ further includesannular flaps flexible membrane 44′. Theseannular flaps flexible membrane 44′. Alternatively, theseannular flaps flexible membrane 44′. Theannular flaps flexible membrane 44′ are attached to the base 14 using one or more joint screws, an adhesive material or any other means to physically attach theflaps flexible membrane 44′ to thebase 14, as illustrated inFIG. 13A . However, in other embodiments, the polishinghead 10B may include annular discs, similar to theannular discs 40A-40C of the polishinghead 10, which can be used to secure the outerflexible membrane 44′. The inner sidewall and theannular flap 45A of the outerflexible membrane 44′, along with the bottom surface of thebase 14 and the upper surface of the outerflexible membrane 44′, form theannular chamber 46A′. Theannular flaps base 14 and the upper surface of the outerflexible membrane 44′, form theannular chamber 46B′. Theannular flap 45B and the outer sidewall of the outerflexible membrane 44′, along with the bottom surface of the base and the upper surface of the outerflexible membrane 44′, form theannular chamber 46C′. Theannular chambers 46A′, 46B′ and 46C′ are connected to thefluid channels fluid channel 34E since there are no inner flexible membranes. - The polishing
head 10B operates in a manner similar to that of the polishinghead 10A with respect to the processes of chucking the wafer W onto the polishinghead 10B, polishing the wafer on the polishingsurface 11 using the polishinghead 10B and de-chucking the wafer from the polishinghead 10B in accordance with an embodiment of the invention. - In order to chuck the wafer W onto the polishing
head 10B, suction is applied to thecentral cavity 50 via thefluid channel 34D. Suction is also applied directly to theannular chamber 46A′ via thefluid channel 34A through the three-way valve 710A and the manifold 702C of the valve-regulator assembly 28 to evacuate the gas in theannular chamber 46A′ and deflate theannular chamber 46A′. However, theannular chambers FIG. 13B . This process is similar to the process described above for the polishinghead 10A with reference toFIG. 12B . The deflation of theannular chamber 46A′ with the inflation of theannular chambers 46B′ and 46C′ produce a largecircular depression 304″ on the bottom surface of the outerflexible membrane 44′ to better hold the wafer W, as illustrated inFIG. 13B . - In order to polish the wafer W on the polishing
surface 11, the polishinghead 10B with the chucked wafer is moved over the polishing surface. The polishinghead 10B is then lowered onto the polishingsurface 11 such that theretainer ring 16 contacts the polishing surface. Next, the first, second and thirdannular chambers 46A′-46C′ are inflated or pressurized by supplying gas with same or different pressures to theannular chambers 46A′-46C′ through thepressure regulators 704A-704C, respectively, of the valve-and-regulator assembly 28. As a result, theannular chambers 46A′-46C′ are inflated, which push the bottom surface of the outerflexible membrane 44 toward the polishingsurface 11, and thus, applies same or different pressures to the wafer on the polishingsurface 11 during the polishing process. - In this manner, the pressures applied to the wafer W can be controlled in terms of zones of the wafer. The pressure applied to a central zone that is under the first
annular chamber 46A′ is controlled by the pressure in that chamber. The pressure applied to an intermediate annular zone surrounding the central zone that is under the secondannular chamber 46B′ is controlled by that chamber. The pressure applied to an outer annular zone surrounding the intermediate annular zone that is under the thirdannular chamber 46C′ is controlled by that chamber. By applying different pressures to the respective zones, polishing rates at the respective zones can be controlled individually. - During the polishing process, the suction applied to the
central cavity 50″ may be removed. Alternatively, instead of removing the suction applied to thecentral cavity 50″ during the polishing process, the applied suction can be used to detect wafer slippage. If the wafer W is slipped out from the polishinghead 10B during the polishing process, the pressure of the suction will be changed. By detecting this pressure change, the wafer slippage can be detected. - After the polishing process is finished, the suction is again applied to the
central cavity 50″ in order to hold the wafer W. In order to create thecircular depression 304″, theannular chamber 46A′ is opened to the manifold 702C through the three-way valve 710A in manner similar to the process described above with reference toFIG. 7B . - Next, the polishing
head 10B is transferred to a wafer unload station (not shown) and then the wafer is unloaded or de-chucked to the wafer unload station. In order to de-chuck the wafer from the polishinghead 10B, the suction is no longer applied to thecentral cavity 50″. Furthermore, pressurized gas may be applied to theannular chamber 46A′ through thefluid channel 34A in order to unload the wafer onto the wafer unload station. Alternatively, D.I. water can be applied to the wafer through thecentral cavity 50″ via thefluid channel 34D in order to unload the wafer onto the wafer unload station. - Turning now to
FIG. 14A , a polishinghead 10C for polishing a semiconductor wafer W according to another embodiment of the present invention is shown. The polishinghead 10C is similar to the polishinghead 10 ofFIG. 1 and includes most of the elements of the polishinghead 10. Thus, inFIG. 14A , the reference numbers ofFIG. 1 are used to indicate these common elements. One of differences between the polishinghead 10C and the polishinghead 10 is that the polishinghead 10C includes a firstannular disc 40A″, which has a flat bottom surface similar to theannular disc 40A′ of the polishinghead 10A. However, the firstannular disc 40A″ of the polishinghead 10C is configured such that its thickness, or vertical width, is less than that of the secondannular disc 40B and the thirdannular disc 40C. Another difference between the polishinghead 10C and the polishinghead 10 is that the polishinghead 10C includes only the second and third innerflexible membranes annular chamber 46A of the polishinghead 10. Rather, the polishinghead 10C includes an outerflexible membrane 44″ that is configured to form an innermostannular chamber 46A″, which is surrounded by the secondannular chamber 46B. - In an embodiment, the outer
flexible membrane 44″ is similar in construction to the outerflexible membrane 44 of the polishinghead 10. In the illustrated embodiment, the outerflexible membrane 44″ includes only one annular upside downU-shaped portion 54″ at its periphery. However, in other embodiments, the outerflexible membrane 44″ may include another annular upside down U-shaped portion near its center, similar to the annular upside downU-shaped portion 56 of the outerflexible membrane 44 of the polishinghead 10. In addition, the outerflexible membrane 44″ has acentral cavity 150, which is defined by an innerannular sidewall 152 of the outerflexible membrane 44″. The outerflexible membrane 44″ further includes anannular flap 45″ on the upper surface of the outerflexible membrane 44″. Theannular flap 45″ may be a separate piece of material, which is attached to the upper surface of the outerflexible membrane 44″. Alternatively, theannular flap 45″ may be an integral part of the outerflexible membrane 44″. Theannular flap 45″ and theinner sidewall 152 of the outerflexible membrane 44″ are attached to the base 14″ using one or more joint screws, an adhesive material or any other means to physically attach the flap to the base 14″, as illustrated inFIG. 14A . Theannular chamber 46A″ is connected to thefluid channel 34A. - The polishing
head 10C operates in a manner similar to that of the polishinghead 10 with respect to the processes of chucking the wafer W onto the polishinghead 10C, polishing the wafer on the polishingsurface 11 using the polishinghead 10C and de-chucking the wafer from the polishinghead 10C in accordance with an embodiment of the invention. As illustrated inFIG. 14B , theannular chambers annular chambers - With reference to a process flow diagram of
FIG. 15 , a method of chucking a semiconductor wafer onto a polishing head in accordance with an embodiment of the invention is described. Atblock 1502, the semiconductor wafer is positioned against a lower surface of an outer flexible membrane of the polishing head. The outer flexible membrane is positioned below a base structure of the polishing head such that at least a first annular chamber and a second annular chamber are positioned between the base structure and the outer flexible membrane. The polishing head includes a central cavity positioned below the base structure and at least partly defined by the outer flexible membrane. The central cavity is open at the lower surface of the outer flexible membrane. Atblock 1504, the pressure in the first annular chamber is reduced to deflate the first annular chamber. Atblock 1506, suction is applied to the central cavity to chuck the semiconductor wafer onto the lower surface of the outer flexible membrane. - Although the foregoing description sets forth exemplary embodiments and methods of operation of the invention, the scope of the invention is not limited to these specific embodiments or described methods of operation. Many details have been disclosed that are not necessary to practice the invention, but have been included to sufficiently disclose the best mode of operation and manner and process of making and using the invention. Modification may be made to the specific form and design of the invention without departing from its spirit and scope as expressed in the following claims.
Claims (31)
1. A polishing head for polishing a semiconductor wafer comprising:
a base structure;
an outer flexible membrane positioned below said base structure such that at least a first annular chamber and a second annular chamber are positioned between said base structure and said outer flexible membrane, said second annular chamber being positioned to surround said first annular chamber, a lower surface of said outer flexible membrane being used to contact said semiconductor wafer;
a central cavity positioned below said base structure and at least partly defined by said outer flexible membrane, said central cavity being open at said lower surface of said outer flexible membrane;
a first fluid channel connected to said first annular chamber to supply pressurized fluid and to apply suction to said first chamber;
a second fluid channel connected to said second annular chamber to supply pressurized fluid to said second chamber; and
a third fluid channel connected to said central cavity, said third fluid channel being used to apply suction directly to said semiconductor wafer through the central cavity to hold said semiconductor wafer onto said outer flexible membrane.
2. The polishing head of claim 1 further comprising:
a third annular chamber positioned between said base structure and said outer flexible membrane, said third annular chamber being positioned to surround said second annular chamber; and
a fourth fluid channel connected to said third annular chamber to supply pressurized fluid to said third chamber.
3. The polishing head of claim 1 wherein said outer flexible membrane includes an annular flap on an upper surface of said outer flexible membrane, said first annular chamber being at least partly defined by said annular flap and said upper surface of said outer flexible membrane and said base structure.
4. The polishing head of claim 3 wherein said outer flexible membrane includes another annular flap on said upper surface of said outer flexible membrane, said second annular chamber being at least partly defined by said annular flap, said another annular flap and said upper surface of said outer flexible membrane and said base structure.
5. The polishing head of claim 4 further comprising:
a third annular chamber positioned between said base structure and said outer flexible membrane, said third annular chamber being positioned to surround said second annular chamber, said third annular chamber being at least partly defined by said another annular flap and said upper surface of said outer flexible membrane and said base structure; and
a fourth fluid channel connected to said third annular chamber to supply pressurized fluid to said third chamber.
6. The polishing head of claim 3 further comprising an inner annular flexible membrane positioned between said base structure and said outer flexible membrane, said inner annular flexible membrane and said base structure at least partly defining said second annular chamber.
7. The polishing head of claim 6 further comprising a fourth fluid channel connected to a space between said outer flexible membrane and said inner annular flexible membrane, said fourth fluid channel being used to selectively apply suction to said space.
8. The polishing head of claim 6 further comprising:
another inner annular flexible membrane positioned between said base structure and said outer flexible membrane, said another inner annular flexible membrane being positioned to surround said inner annular flexible membrane, said another inner annular flexible membrane and said base structure at least partly defining a third annular chamber that surround said second annular chamber; and
a fourth fluid channel connected to said third annular chamber to supply pressurized fluid to said third chamber.
9. The polishing head of claim 1 wherein said base structure includes a base and a plurality of annular discs attached to a bottom surface of said base, said annular discs having bottom surfaces that at least partly define said first and second annular chambers.
10. The polishing head of claim 9 wherein said annular discs include a recess region on one of said bottom surfaces of said annular discs.
11. The polishing head of claim 9 wherein at least one of said annular discs has a vertical thickness that is less than the vertical thickness of other annular discs.
12. The polishing head of claim 1 wherein said outer flexible membrane is configured to include an annular upside down U-shaped portion.
13. The polishing head of claim 1 further comprising a housing attached to said base structure and a valve-and-regulator assembly positioned within said housing, said valve-and-regulator assembly being connected to said first and second fluid channels.
14. The polishing head of claim 13 wherein said valve-and-regulator assembly is configured to selectively provide suction to at least one of said first and second fluid channels to apply said suction to at least one of said first and second annular chambers.
15. The polishing head of claim 13 wherein said valve-and-regulator assembly is configured to selectively provide suction to said first fluid channel to apply said suction to said first annular chamber, and said valve-and-regulator assembly being further configured to selectively release fluid in said second annular chamber.
16. A polishing head for polishing a semiconductor wafer comprising:
a base structure;
an outer flexible membrane positioned below said base structure such that at least a first annular chamber and a second annular chamber are positioned between said base structure and said outer flexible membrane, said second annular chamber being positioned to surround said first annular chamber, a lower surface of said outer flexible membrane being used to contact said semiconductor wafer;
a central cavity positioned below said base structure and at least partly defined by said outer flexible membrane, said central cavity being open at said lower surface of said outer flexible membrane;
a first inner annular flexible membrane positioned between said base structure and said outer flexible membrane, said first inner annular flexible membrane and said base structure at least partly defining said first annular chamber;
a second inner annular flexible membrane positioned between said base structure and said outer flexible membrane, said second inner annular flexible membrane and said base structure at least partly defining said second annular chamber;
a first fluid channel connected to said first annular chamber to supply pressurized fluid to said first chamber;
a second fluid channel connected to said second annular chamber to supply pressurized fluid to said second chamber;
a third fluid channel connected to a space between said outer flexible membrane and said first and second inner annular flexible membranes, said third fluid channel being used to selectively apply suction to said space; and
a fourth fluid channel connected to said central cavity, said fourth fluid channel being used to apply suction directly to said semiconductor wafer through said central cavity to hold said semiconductor wafer onto said outer flexible membrane.
17. The polishing head of claim 16 wherein said base structure includes a base and a plurality of annular discs attached to a bottom surface of said base, said annular discs having bottom surfaces that at least partly define said first and second annular chambers.
18. The polishing head of claim 17 wherein said annular discs include a recess region on one of said bottom surfaces of said annular discs.
19. The polishing head of claim 17 wherein at least one of said annular discs has a vertical thickness that is less than the vertical thickness of other annular discs.
20. A method of chucking a semiconductor wafer onto a polishing head comprising steps of:
positioning said semiconductor wafer against a lower surface of an outer flexible membrane of said polishing head, said outer flexible membrane being positioned below a base structure of said polishing head such that at least a first annular chamber and a second annular chamber are positioned between said base structure and said outer flexible membrane, said polishing head including a central cavity positioned below said base structure and at least partly defined by said outer flexible membrane, said central cavity being open at said lower surface of said outer flexible membrane;
reducing the pressure in said first annular chamber to deflate said first annular chamber; and
applying suction to said central cavity to chuck said semiconductor wafer onto said lower surface of said outer flexible membrane.
21. The method of claim 20 wherein said reducing said pressure in said first annular chamber includes applying suction to said first annular chamber.
22. The method of claim 20 further comprising applying a pressure to said second annular chamber such that said second annular chamber is inflated.
23. The method of claim 20 wherein said outer flexible membrane includes an annular flap on an upper surface of said outer flexible membrane, said first annular chamber being at least partly defined by said annular flap and said upper surface of said outer flexible membrane and said base structure.
24. The method of claim 23 wherein said outer flexible membrane includes another annular flap on said upper surface of said outer flexible membrane, said second annular chamber being at least partly defined by said annular flap, said another annular flap and said upper surface of said outer flexible membrane and said base structure.
25. The method of claim 24 further comprising applying a pressure to a third annular chamber such that said third annular chamber is inflated, said third annular chamber being positioned between said base structure and said outer flexible membrane, said third annular chamber being positioned to surround said second annular chamber, said third annular chamber being at least partly defined by said another annular flap and said upper surface of said outer flexible membrane and said base structure.
26. The method of claim 23 wherein said second annular chamber is at least partly defined by an inner annular flexible membrane and said base structure of said polishing head, said inner annular flexible membrane being positioned between said base structure and said outer flexible membrane.
27. The method of claim 26 further comprising applying another suction to a space between said outer flexible membrane and said inner annular flexible membrane.
28. The method of claim 26 further comprising applying a pressure to a third annular chamber such that said third annular chamber is inflated, said third annular chamber being positioned between said base structure and said outer flexible membrane, said third annular chamber being positioned to surround said second annular chamber, said third annular chamber being at least partly defined by another inner annular flexible membrane and said base structure, said another inner annular flexible membrane being positioned between said base structure and said outer flexible membrane such that said inner annular flexible membrane is surrounded by said another inner annular flexible membrane.
29. The method of claim 20 wherein said first annular chamber is at least partly defined by a first inner annular flexible membrane and said base structure, said first inner annular flexible membrane being positioned between said base structure and said outer flexible membrane, and wherein said second annular chamber is at least partly defined by a second inner annular flexible membrane, said second inner annular flexible membrane being positioned between said base structure and said outer flexible membrane.
30. The method of claim 29 further comprising applying a pressure to a third annular chamber such that said third annular chamber is inflated, said third annular chamber being positioned between said base structure and said outer flexible membrane such that said second annular chamber is surrounded by said third annular chamber, said third annular chamber being at least partly defined a third inner annular flexible membrane positioned between said base structure and said outer flexible membrane.
31. The method of claim 29 further comprising applying another suction to a space between said outer flexible membrane and said inner annular flexible membranes.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/774,532 US20080014842A1 (en) | 2006-03-03 | 2007-07-06 | Polishing head for polishing semiconductor wafers |
Applications Claiming Priority (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US77867506P | 2006-03-03 | 2006-03-03 | |
US80046806P | 2006-05-15 | 2006-05-15 | |
US83489006P | 2006-08-01 | 2006-08-01 | |
US83710906P | 2006-08-11 | 2006-08-11 | |
US84473706P | 2006-09-15 | 2006-09-15 | |
US11/680,588 US7364496B2 (en) | 2006-03-03 | 2007-02-28 | Polishing head for polishing semiconductor wafers |
US11/774,532 US20080014842A1 (en) | 2006-03-03 | 2007-07-06 | Polishing head for polishing semiconductor wafers |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/680,588 Continuation-In-Part US7364496B2 (en) | 2006-03-03 | 2007-02-28 | Polishing head for polishing semiconductor wafers |
Publications (1)
Publication Number | Publication Date |
---|---|
US20080014842A1 true US20080014842A1 (en) | 2008-01-17 |
Family
ID=46045471
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/774,532 Abandoned US20080014842A1 (en) | 2006-03-03 | 2007-07-06 | Polishing head for polishing semiconductor wafers |
Country Status (1)
Country | Link |
---|---|
US (1) | US20080014842A1 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090242125A1 (en) * | 2008-03-25 | 2009-10-01 | Applied Materials, Inc. | Carrier Head Membrane |
US8475231B2 (en) | 2008-12-12 | 2013-07-02 | Applied Materials, Inc. | Carrier head membrane |
US20140113531A1 (en) * | 2011-06-29 | 2014-04-24 | Shin-Etsu Handotai Co., Ltd. | Polishing head and polishing apparatus |
US20150093971A1 (en) * | 2010-09-08 | 2015-04-02 | Ebara Corporation | Polishing apparatus and method |
US9393668B2 (en) | 2012-07-12 | 2016-07-19 | Taiwan Semiconductor Manufacturing Company Limited | Polishing head with alignment gear |
WO2020253869A1 (en) * | 2019-06-21 | 2020-12-24 | 清华大学 | Air film for chemical mechanical polishing head, chemical mechanical polishing head, and polishing device |
WO2024025839A1 (en) * | 2022-07-26 | 2024-02-01 | Axus Technology Llc | Carrier for polishing workpieces with flats or voids |
-
2007
- 2007-07-06 US US11/774,532 patent/US20080014842A1/en not_active Abandoned
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20090242125A1 (en) * | 2008-03-25 | 2009-10-01 | Applied Materials, Inc. | Carrier Head Membrane |
US8475231B2 (en) | 2008-12-12 | 2013-07-02 | Applied Materials, Inc. | Carrier head membrane |
US20150093971A1 (en) * | 2010-09-08 | 2015-04-02 | Ebara Corporation | Polishing apparatus and method |
US9149903B2 (en) * | 2010-09-08 | 2015-10-06 | Ebara Corporation | Polishing apparatus having substrate holding apparatus |
US20140113531A1 (en) * | 2011-06-29 | 2014-04-24 | Shin-Etsu Handotai Co., Ltd. | Polishing head and polishing apparatus |
US9393668B2 (en) | 2012-07-12 | 2016-07-19 | Taiwan Semiconductor Manufacturing Company Limited | Polishing head with alignment gear |
WO2020253869A1 (en) * | 2019-06-21 | 2020-12-24 | 清华大学 | Air film for chemical mechanical polishing head, chemical mechanical polishing head, and polishing device |
WO2024025839A1 (en) * | 2022-07-26 | 2024-02-01 | Axus Technology Llc | Carrier for polishing workpieces with flats or voids |
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Owner name: KOMICO TECHNOLOGY, INC., TEXAS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INOPLA INC.;REEL/FRAME:022917/0246 Effective date: 20090507 Owner name: KOMICO TECHNOLOGY, INC.,TEXAS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INOPLA INC.;REEL/FRAME:022917/0246 Effective date: 20090507 |
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STCB | Information on status: application discontinuation |
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