Polishing system with air exhaust system

Information

  • Patent Grant
  • 6783427
  • Patent Number
    6,783,427
  • Date Filed
    Tuesday, October 22, 2002
    22 years ago
  • Date Issued
    Tuesday, August 31, 2004
    21 years ago
Abstract
A polishing apparatus comprises: a housing defining a chamber wherein articles to be polished are subject to polishing and cleaning operations; partition walls for dividing the chamber of the housing into a plurality of sections; and, an air exhaust device. The exhaust device comprises: air exhaust conduits which are fluidly connected to the sections in the housing to exhaust air from the sections; valves for closing and opening the air exhaust conduits, respectively; and, a controller for independently controlling the valves to regulate air flows exhausted through the conduits. The conduits have inlet openings located in a vicinity of spaces where any air pollutant is generated in the sections in the housing.
Description




BACKGROUND OF THE INVENTION




This invention relates to a system for polishing articles such as semiconductor wafers, which is provided with an air exhaust system for creating a negative pressure in a housing of the polishing system.




During production of semiconductor devices, it is common to use a polishing system in which semiconductor wafers are subjected to a so-called chemical mechanical polishing (CMP) process to form a highly planarized surface for formation of an integrated circuit. During a chemical mechanical polishing process, semiconductor wafers are slidably engaged with and moved relative to a polishing surface, which surface is usually provided on an upper side of a turntable, and a chemical polishing liquid referred to as slurry is concurrently supplied onto the polishing surface.




Semiconductor devices are produced in a clean room, and a polishing system such as that mentioned above is installed in the clean room. During a polishing operation pollutants are generated, which may include: particles of polishing liquid scattered from a polishing surface; debris generated from a wafer or from a polishing surface; particles generated in driving assemblies for driving a turntable, and in cleaning machines for cleaning wafers which have been polished, and also in wafer transporting devices; and harmful gases emitted from a chemical cleaning liquid. It is necessary to prevent such pollutants from leaving a housing of the polishing system and entering the clean room. To this end, a pressure in the housing of the polishing system is kept lower than that in the clean room by exhausting or drawing out air from the housing.




However, since a volume of the housing of the polishing system is large, a large amount of energy is required to create a negative pressure in the housing relative to the clean room.




SUMMARY OF THE INVENTION




Accordingly, it is an object of the present invention to provide a polishing system with an air exhaust system which can efficiently exhaust or draw out air from a housing to create negative pressures in the housing, which are required to prevent pollutants, such as particles of a polishing liquid, from leaking from the housing.




According to one aspect of the present invention, there is provided a polishing system comprising:




a housing defining a chamber in which articles to be polished are subject to polishing and cleaning operations;




partition walls for dividing the chamber of the housing into a plurality of sections; and,




an air exhaust device comprising:




air exhaust conduits which are fluidly connected to sections in the housing to exhaust air from the sections;




valves for closing and opening respective ones of the air exhaust conduits, the conduits having inlet openings located in a vicinity of spaces where any air pollutant is generated in the sections in the housing; and,




a controller for independently controlling the valves to regulate air flows exhausted through the conduits.




In the polishing system of the present invention, since the inlet openings of the conduits are positioned in a vicinity of spaces where an air pollutant may be generated in the polishing system housing, any air pollutant can be efficiently discharged from the housing to prevent leakage of the air pollutant from the housing into space of a clean room, even in a case that a negative pressure employed in the housing is not as great as that employed in a housing of a conventional polishing system having an air exhaust system. Further, in the polishing system of the present invention, it is possible to independently control the valves. This makes it possible for the air exhaust system to perform an efficient and effective air exhaust operation, by conducting such an operation on a basis of various conditions such as an air pressure in various sections in the housing of the polishing system, a degree of air pollutants in the sections, and the like.











BRIEF DESCRIPTION OF THE DRAWINGS




Further objects and advantages of the present invention will be apparent from the following description made with reference to the accompanying drawings showing a preferred embodiment of the present invention.




In the Drawings





FIG. 1

is a top plan view of a polishing system in accordance with an embodiment of the subject invention, with a ceiling wall of a housing of the polishing system cut away to provide a clear view of an interior of the housing; and,





FIG. 2

is a schematic cross sectional side elevational view of a main portion of the polishing system of

FIG. 1

showing an air exhaust system installed in the polishing system.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




As shown in

FIGS. 1 and 2

, a polishing system in accordance with a preferred embodiment of the present invention has a housing


10


which is divided by partition walls


13


into a pair of polishing sections


11


,


11


, a cleaning section


12


and a wafer intake/outtake section


25


. An exterior of the wafer intake/outtake section


25


is adapted to receive wafer storage cassettes


27


-


1


,


27


-


1


,


27


-


3


and


27


-


4


.




In each of the polishing sections


11


,


11


, a turntable


15


is provided, along with a motor M for drivingly rotating the turntable


15


about its vertical axis. As shown in

FIG. 2

, each polishing section is divided by a partition wall


14


into an upper area in which the turntable


15


is provided, with a cup-like slurry drainage member


16


being provided to surround the turntable


15


, and a lower area in which the motor M is provided. Each of the polishing sections


11


,


11


is further provided with a wafer carrier


29


, and a pair of wafer transfer trays


17


,


17


adapted to be horizontally moved by corresponding motors such as air cylinders


17


-


1


,


17


-


2


to either a left position or a right position, as shown in FIG.


1


. The wafer carrier


29


is pivotable about a vertical axis


29


-


1


between a position shown in

FIG. 1

where the wafer carrier brings a wafer into contact with a polishing surface provided on an upper side surface of the turntable


15


, and a position where the wafer carrier


29


is positioned above the wafer transfer tray


17


at the left position to receive a pre-polishing wafer from the wafer tray


17


, or to return a post-polishing wafer onto the wafer tray


17


. In

FIG. 2

, reference numeral


18


-


1


denotes a first wafer lift having a motor such as an air cylinder provided at its lower end for moving the first wafer lift either up or down to transfer a wafer from the wafer tray


17


at the left position to the wafer carrier


29


, and vice versa. Reference numeral


18


-


2


denotes a second wafer lift which is also provided at its lower end with a motor for moving the second wafer lift


18


-


2


either up or down to transfer a wafer from the wafer tray


17


at the right position to a reverser


30


provided over the wafer tray


17


, and vice versa. The reverser


30


is adapted to turn upside down a wafer received from a transfer robot


23


provided inside the cleaning section


12


(to be described in detail later) to pass the wafer to the second wafer lift


18


-


2


, and also to turn upside down a wafer received from the second wafer lift


18


-


2


to pass it to the transfer robot


23


.




In the cleaning section


12


, provided is a pair of primary cleaning machines


19


,


19


along with a pair of secondary cleaning machines


20


,


20


arranged in tandem. In a central area of the cleaning section


12


, there are provided the transfer robot


23


and a wafer table


24


. The transfer robot


23


is adapted to pick up a pre-polishing wafer, supplied onto the table


24


from the wafer intake/outtake section


25


, and transfer it to reverser


30


in polishing section


11


, and to take a polished wafer from the reverser


30


to transfer it first to primary cleaning machine


19


, and then to secondary cleaning machine


20


. Each secondary cleaning machine


20


can perform a spin-drying operation in addition to a wafer cleaning operation so that a wafer is substantially completely dried thereby.




In the wafer intake/outtake section


25


, there is provided a transfer robot


26


adapted to remove a pre-polishing wafer from any one of the wafer storage cassettes


27


-


1


,


27


-


2


,


27


-


3


and


27


-


4


and place it on the wafer table


24


in the cleaning section


12


, and to take a polished wafer from secondary cleaning machine


20


and return it to one of the wafer storage cassettes.





FIG. 2

shows an air exhaust system provided in the polishing system. The air exhaust system comprises a plurality of conduits L


1


, L


2


, L


3


, L


4


, L


5


, L


6


, and L


7


that are fluidly connected to the housing


10


; specifically, to the upper and lower parts of each polishing section


11


and the cleaning section


12


of the housing. The conduits L


1


, L


2


, L


3


, L


4


, L


5


, L


6


, and L


7


have outlet openings (not shown) connected to an air draw device (not shown), for example a vacuum pump, and input openings which are, with the exception of conduit L


5


, positioned in a vicinity of spaces where an air pollutant is generated. Specifically, the inlet opening of each conduit L


1


is provided in slurry drainage member


16


near turntable


15


since during a polishing operation polishing liquid and debris are scattered from both a wafer being polished and the polishing surface. The inlet opening of each conduit L


2


is open to an interior of a motor casing enclosing a drive assembly of motor M, since particles may be generated therefrom as a result of frictional engagement between movable elements of the drive assembly. The inlet openings of each conduit L


4


and each conduit L


3


are positioned near air cylinders or motors


17


-


1


,


17


-


2


of wafer trays


17


,


17


, and the air cylinders or motors of lifts


18


-


1


,


18


-


2


, respectively. The inlet openings of each conduit L


6


and each conduit L


7


are open to an interior of primary and secondary cleaning machines


19


,


20


, respectively. The conduits L


1


, L


2


, L


3


, L


4


, L


5


, L


6


, and L


7


are provided with valves V


1


, V


2


, V


3


, V


4


, V


5


, V


6


, and V


7


, respectively, which are connected to a controller


22


for controlling opening and closing of the valves V


1


, V


2


, V


3


, V


4


, V


5


, V


6


, and V


7


to independently regulate air exhausted through the conduits L


1


, L


2


, L


3


, L


4


, L


5


, L


6


, and L


7


.




The conduit L


5


is provided with a return branch to return air drawn from the cleaning section


12


to the same section through a filter


21


mounted on a top of the housing


10


. Each polishing section


11


is provided with an additional air vent conduit (not denoted by any reference numeral) at a left upper portion thereof.




Operation of the air exhaust system described above will now be explained. As stated above, to maintain a negative pressure inside of the system housing


10


relative to a clean room to prevent air leakage from the system housing


10


into the clean room, it is essential for the air exhaust system to be operated. Further, the air exhaust system is capable of generating different pressures in different sections in the system housing


10


divided by the partition walls


13


and


14


. Specifically, a pressure in polishing section


11


which, generally, is most susceptible to contamination by air pollutants, is made lower than that in the cleaning section


12


. Although no air exhaust conduits for the wafer intake/outtake section


25


are shown, pressure in the section


25


is also controlled by virtue of air vent conduits similar to those described above. Specifically, the section


25


is usually kept at a higher pressure than the clean room as well as the sections


11


and


12


. An air supply system (not shown) may be provided to supply clean air from outside to the section


25


to, for example, keep this section at a high pressure relative to the other sections


11


and


12


and the clean room.




The controller


22


controls the valves V


1


, V


2


, V


3


, V


4


, V


5


, V


6


, and V


7


taking into account air pressure and/or air contaminant conditions in respective spaces in the system housing; and it is possible to selectively open any of the valves V


1


, V


2


, V


3


, V


4


, V


5


, V


6


, and V


7


. For example, during a polishing operation, only valves V


1


and V


7


will be opened when it is determined that it is sufficient to exhaust air through the conduits L


1


and L


7


to prevent pollutants generated during the polishing operation from leaking into the clean room. Such control of the valves leads to an effective saving of energy expended in creating negative pressures needed to prevent pollutant leakage into the clean room. Further, during a waiting period for a next polishing operation, only valve V


1


may be opened while the other valves are closed, as it is generally unnecessary to conduct air exhaust through the conduits L


2


-L


7


. In a polishing system in accordance with this embodiment, while a total amount of air to be exhausted through all of the conduits L


1


, L


2


, L


3


, L


4


, L


5


, L


6


, and L


7


amounts to 52 m


3


, an amount of air exhausted through conduits L


1


amounts to 11m


3


, whereby energy for exhausting air from the polishing system is greatly decreased.




Furthermore, it is possible to open the valves V


1


, V


2


, V


3


, V


4


, V


5


, V


6


, and V


7


intermittently during an air-exhaust operation.




Control of the valves V


1


, V


2


, V


3


, V


4


, V


5


, V


6


, and V


7


may be performed on a basis of air pressures in the housing sensed by pressure sensors S provided at predetermined positions in the housing. Specifically, valve control may be conducted on a basis of comparison of sensed pressures with predetermined pressure values. Although a specific embodiment of the present invention has been described in the foregoing, it should be understood that the present invention is not limited to this embodiment, and a variety of modifications and changes are possible within the spirit and scope of the present invention. For example, the valve control as described above will be applicable to control an air supply conduit system with which the polishing system described above may be provided, to the extent that a controller independently controls valves provided in respective air supply conduits of the air supply conduit system which are fluidly connected to respective sections of the housing of the polishing system. Further, it should be noted that the present invention is applicable to apparatuses as disclosed in Japanese Patent Applications 7-344797, 9-33784, 11-545612, 10-189704 and 2000-250392.



Claims
  • 1. A polishing apparatus comprising:a housing defining a chamber wherein articles are to be subjected to polishing and cleaning operations; at least one partition wall for dividing said chamber into sections; pressure sensors provided at predetermined positions in said housing; and an air exhaust device including (i) air exhaust conduits fluidly connected to said sections to exhaust air from said sections; said air exhaust conduits having inlet openings located in a vicinity of spaces where an air pollutant can be generated in said sections, (ii) valves for closing and opening said air exhaust conduits, respectively and (iii) a controller for independently controlling said valves on a basis of comparison of pressures sensed by said pressure sensors with predetermined pressure values so as to regulate air flows exhausted through said air exhaust conduits, such that different pressures can be generated in different ones of said sections.
  • 2. The polishing apparatus according to claim 1, whereinsaid controller is adapted to selectively open said valves to exhaust air from the spaces which are desired to be air-exhausted.
  • 3. The polishing apparatus according to claim 2, whereinsaid sections comprise a polishing section and a cleaning section, with (i) said polishing section being provided with a turntable having on one of its sides a polishing surface, and a motor for drivingly rotating the turntable, and (ii) said cleaning section being provided with a cleaning machine for cleaning semiconductor wafers which have been subjected to a polishing operation, and said air exhaust conduits are fluidly connected to said polishing section and said cleaning section, respectively, with said air exhaust conduit fluidly connected to said polishing section having an inlet opening positioned in the vicinity of said turntable.
  • 4. The polishing apparatus according to claim 3, whereinsaid polishing section has a polishing operation section and a motor section divided by a partition wall so that said turntable is positioned in said polishing operation section and said motor is positioned in said motor section, and said air exhaust conduits include a conduit fluidly connected to an interior of a housing of said motor to exhaust air therefrom.
  • 5. The polishing apparatus according to claim 4, whereinsaid air exhaust conduits include a conduit fluidly connected to an interior of said cleaning machine to exhaust air therefrom.
  • 6. The polishing apparatus according to claim 3, whereinsaid air exhaust conduits include a conduit fluidly connected to an interior of said cleaning machine to exhaust air therefrom.
  • 7. The polishing apparatus according to claim 1, wherein said controller is adapted to control at least one of said valves intermittently.
  • 8. The polishing apparatus according to claim 7, whereinsaid sections comprise a polishing section and a cleaning section, with (i) said polishing section being provided with a turntable having on one of its sides a polishing surface, and a motor for drivingly rotating said turntable, and (ii) said cleaning section being provided with a cleaning machine for cleaning semiconductor wafers which have been subjected to a polishing operation, and said air exhaust conduits are fluidly connected to said polishing section and said cleaning section, respectively, with said air exhaust conduit fluidly connected to said polishing section having an inlet opening positioned in the vicinity of said turntable.
  • 9. The polishing apparatus according to claim 8, whereinsaid polishing section has a polishing operation section and a motor section divided by a partition wall so that said turntable is positioned in said polishing operation section and said motor is positioned in said motor section, and said air exhaust conduits include a conduit fluidly connected to an interior of a housing of said motor to exhaust air therefrom.
  • 10. The polishing apparatus according to claim 9, whereinsaid air exhaust conduits include a conduit fluidly connected to an interior of said cleaning machine to exhaust air therefrom.
  • 11. The polishing apparatus according to claim 8, whereinsaid air exhaust conduits include a conduit fluidly connected to an interior of said cleaning machine to exhaust air therefrom.
  • 12. The polishing apparatus according to claim 1, whereinsaid sections comprise a polishing section and a cleaning section, with (i) said polishing section being provided with a turntable having on one of its sides a polishing surface, and a motor for drivingly rotating said turntable, and (ii) said cleaning section being provided with a cleaning machine for cleaning semiconductor wafers which have been subjected to a polishing operation, and said air exhaust conduits are fluidly connected to said polishing section and said cleaning section, respectively, with said air exhaust conduit fluidly connected to said polishing section having an inlet opening positioned in the vicinity of said turntable.
  • 13. The polishing apparatus according to claim 12, whereinsaid polishing section has a polishing operation section and a motor section divided by a partition wall so that said turntable is positioned in said polishing operation section and said motor is positioned in said motor section, and said air exhaust conduits include a conduit fluidly connected to an interior of a housing of said motor to exhaust air therefrom.
  • 14. The polishing apparatus according to claim 13, whereinsaid air exhaust conduits include a conduit fluidly connected to an interior of said cleaning machine to exhaust air therefrom.
  • 15. The polishing apparatus according to claim 12, whereinsaid air exhaust conduits include a conduit fluidly connected to an interior of said cleaning machine to exhaust air therefrom.
  • 16. A polishing apparatus comprising:a housing defining a chamber wherein articles are to be subjected to polishing and cleaning operations; at least one partition wall for dividing said chamber into sections; pressure sensors provided at predetermined positions in said housing; and an air exhaust device including (i) air exhaust conduits fluidly connected to said sections to exhaust air from said sections, said air exhaust conduits respectively having inlet openings at least one of which is located in a vicinity of a space where an air pollutant can be generated in at least one of said sections, (ii) valves for closing and opening said air exhaust conduits, respectively, and (iii) a controller for controlling at least one of said valves on a basis of comparison of pressures sensed by said pressure sensors with predetermined pressure values so as to regulate an air flow exhausted through said at least one of said air exhaust conduits, such that different pressures can be generated in different ones of said sections.
  • 17. The polishing apparatus according to claim 16, whereinsaid sections comprise a polishing section and a cleaning section, with (i) said polishing section being provided with a turntable having on one of its sides a polishing surface, and a motor for drivingly rotating said turntable, and (ii) said cleaning section being provided with a cleaning machine for cleaning semiconductor wafers which have been subjected to a polishing operation, and said air exhaust conduits are fluidly connected to said polishing section and said cleaning section, respectively, with said air exhaust conduit fluidly connected to said polishing section having an inlet opening positioned in the vicinity of said turntable.
  • 18. The polishing apparatus according to claim 17, whereinsaid polishing section has a polishing operation section and a motor section divided by a partition wall so that said turntable is positioned in said polishing operation section and said motor is positioned in said motor section, and said air exhaust conduits include a conduit fluidly connected to an interior of a housing of said motor to exhaust air therefrom.
  • 19. The polishing apparatus according to claim 18, whereinsaid air exhaust conduits include a conduit fluidly connected to an interior of said cleaning machine to exhaust air therefrom.
  • 20. The polishing apparatus according to claim 17, whereinsaid air exhaust conduits include a conduit fluidly connected to an interior of said cleaning machine to exhaust air therefrom.
Priority Claims (1)
Number Date Country Kind
2001/323860 Oct 2001 JP
US Referenced Citations (12)
Number Name Date Kind
5655954 Oishi et al. Aug 1997 A
5679059 Nishi et al. Oct 1997 A
6110024 Togawa Aug 2000 A
6116986 Togawa et al. Sep 2000 A
6146246 Custer et al. Nov 2000 A
6149500 Takahashi et al. Nov 2000 A
6413154 Togawa et al. Jul 2002 B1
6428400 Togawa et al. Aug 2002 B1
6431948 Atoh Aug 2002 B1
6439962 Ato Aug 2002 B1
6494768 Inaba Dec 2002 B2
6616512 Sotozaki Sep 2003 B2
Foreign Referenced Citations (2)
Number Date Country
2000-012493 Jan 2000 JP
2000-182949 Jun 2000 JP