Load and unload station for semiconductor wafers

• US 6,520,839 B1
• Filed: 03/02/2000
• Issued: 02/18/2003
• Est. Priority Date: 09/10/1997
• Status: Expired due to Fees

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: SpeedFam-Ipec Corporation (Lam Research Corporation)
• Inventors: Karlsrud, Chris, Gonzalez-Martin, Jose R.
• Primary Examiner(s): Banks, Derris H.
• Application Number:
  US09/518,158
• Time in Patent Office: 1,083 Days
• Field of Search: 451/28, 451/41, 451/63, 451/285, 451/287, 451/288, 451/289, 451/54, 451/259, 451/339, 451/446, 134/84, 134/94.1, 134/102.1, 134/201, 134/902
• US Class Current: 451/41
• CPC Class Codes: B24B 37/04 designed for working plane surfaces
• CPC Class Codes: B24B 41/005 Feeding or manipulating devices specially adapted to grinding machines feeding, loading or unloading work specially adapted to lapping machines B24B37/345
• CPC Class Codes: H01L 21/02052 Wet cleaning only H01L21/02085 takes precedence

Abstract

An integral machine for polishing, cleaning, rinsing and drying workpieces such as semiconductor wafers. A load/unload station has a plurality of platforms for receiving cassettes of wafers to be processed. A dry end-effector of a robot retrieves wafers from the cassettes and transfers them to an index table. A transfer apparatus having wafer carrier elements picks up wafers from the index table, moves the wafers to a polishing table for polishing, and returns the wafers to the index table for further processing. A flipper moves the polished wafers to a cleaning station. The cleaning station includes scrub stations, a rinsing station and a spin dryer station, and a connective system of water tracks. A wet end-effector of the robot transfers rinsed wafers to the spin dryer station. The dry end-effector of the robot moves dried wafers from the spin dryer station back to the cassette of origination.

Claims

1. An integral machine for polishing, cleaning, rinsing and drying workpieces comprising:

a load/unload station having a plurality of platforms for receiving cassettes of workpieces to be polished, cleaned, rinsed and dried;

first transfer means for retrieving said workpieces from said cassettes;

an index station for receiving unpolished workpieces from said first transfer means and for holding polished workpieces prior to further processing;

a polishing station for polishing unpolished workpieces;

second transfer means for transferring unpolished workpieces from said index station to said polishing station, and for transferring polished workpieces to said index station;

a cleaning station for cleaning, rinsing and drying polished workpieces;

third transfer means for transferring polished workpieces from said index station to said cleaning station; and

fourth transfer means for transferring cleaned, rinsed and dried workpieces from said cleaning station back to said cassettes.

2. A machine as claimed in claim 1, wherein said first and fourth transfer means are incorporated into one robot.

3. A machine as claimed in claim 2, wherein said first transfer means comprises a dry end-effector.

4. A machine as claimed in claim 1, wherein said index station comprises an index table having load cups for holding said unpolished wafers and unload cups for holding said polished wafers.

5. A machine as claimed in claim 4, wherein said second transfer means comprises a movable apparatus having carrier elements which retrieve said unpolished wafers from said load cups;

press said unpolished wafers against a polishing pad in said polishing station; and

return said polished wafers to said unload cups.

6. A machine as claimed in claim 5, wherein said third transfer means comprises a flipper which moves said polished wafers from said unload cups of said index table to said cleaning station.

7. A machine as claimed in claim 1, wherein said cleaning station comprises a plurality of scrub stations, a rinsing station and a drying station.

8. A machine as claimed in claim 7, wherein said wafers are moved between said scrub stations and said rinsing station along a plurality of water tracks.

9. A machine as claimed in claim 8, wherein said first and fourth transfer means are incorporated into a dry end-effector of a robot, and said wafers are moved from said rinsing station to said drying station by a wet end-effector of said robot.

10. A machine having a first station for loading and unloading semiconductor wafers to and from wafer cassettes, a second station for polishing said wafers, a third station for cleaning, rinsing and drying said wafers, and means for transferring said wafers between said first, second and third stations.

11. A method for processing workpieces comprising the following steps:

providing a workpiece to be polished, cleaned, rinsed and dried transferring said workpiece with a robot from a load/unload station to a polishing station;

polishing said workpiece;

transferring said workpiece from said polishing station to a cleaning, rinsing and drying station;

cleaning, rinsing and drying said workpiece; and

transferring said workpiece with said robot from said cleaning station back to said load/unload station.

12. A load/unload station for receiving cassettes of wafers to be processed comprising:

a plurality of platforms having tilted bases thereon for supporting said cassettes, said tilted bases ensuring that said wafers slide to back portions of said cassettes; and

an inner door located on an inner side of said station to isolate said station from an outside environment, and an outer door located on an outer side of said station to permit loading of said cassettes onto said platform, said inner door being configured to close before said outer door may open, and said outer door including a controlled locking mechanism to prevent opening of said outer door while said inner door is open.

13. A station as claimed in claim 12, wherein said bases have an angle of tilt in a range of five to eighteen degrees, said angle being adjustable through use of a mechanism selected from a group consisting of an elevator assembly, a servo assembly, a stepper motor and a torque motor assembly.

14. A station as claimed in claim 13, wherein said platforms further comprise cassette position sensors for monitoring whether said cassettes are properly positioned on said platforms, and outer door sensors for determining whether said outer door is open or closed.

15. A station as claimed in claim 14, wherein said platforms are configured to accommodate cassette configurations selected from a group consisting of six inch wafer cassettes, eight inch wafer cassettes, 300 millimeter wafer cassettes, and Standard Machine Interface wafer pods.

16. A station as claimed in claim 15, and further comprising ionizers to minimize accumulation of static charge in said station and HEPA filters mounted above said station to provide positive laminar air flow exclude airborne particles from said station when said outer door is open.

17. A load/unload station for supporting cassettes of semiconductor wafers to allow automated access to the wafers by an end effector of a robot, the station comprising:

a rearwardly tilted platform comprising a wafer cassette support surface adapted to support wafer cassettes; and

an enclosure surrounding the platform to isolate the station from the platform and surrounding environment, the enclosure equipped with an inner door to the station that allows robot end-effector access to wafers when a cassette is on the platform, and an outer door to the surrounding environment for removing and replacing cassettes on the platform;

whereby an end-effector of a robot in the station is able to remove wafers from and replace wafers when a cassette is supported on the platform, through the inner door, while the rearward tilt of the platform prevents forward spilling of wafers from the cassette.

18. The station of claim 17, wherein the inner and outer doors are controlled to cooperate such that the inner door is closed before the outer door may be opened, to maintain isolation of the station from surroundings.

19. The station of claim 17, further comprising a plurality of platforms, the platforms accessible by a robot in the station.

20. The station of claim 17, wherein an angle of tilt of the platform is adjustable within the range of five to eighteen degrees from horizontal.

21. An automated load/unload station for containers of workpieces, the station comprising:

a robot comprising one end-effector adapted for removing workpieces from containers and another end-effector for replacing workpieces in the container, the robot located in an interior of the station and the interior isolated from surroundings; and

a rearwardly tilted platform adapted for mounting containers of workpieces thereon, the platform surrounded by an enclosure, the enclosure comprising a first access door to the station interior and a second access door to the surroundings, the first access door sized to permit robot end-effector access to a container of workpieces on the platform to remove or replace workpieces, and the second door sized for removal and replacement of containers on the platform.

22. The station of claim 21, wherein the second access door is controlled to remain closed until the first access door is closed.

23. A method of using a semiconductor wafer load/unload station comprising an enclosed rearwardly tilted platform and a robot in an interior of the station, the robot having an end-effector adapted for retrieving wafers from a wafer container and replacing wafers in the container when the container is mounted on the platform, the method comprising:

placing a container of wafers on the platform and sensing secure placement, while maintaining isolation of the station interior from surroundings;

robotically removing a wafer from the container on the platform;

robotically inserting a wafer into the container; and

removing the container from the platform while maintaining isolation of the station interior from surroundings.

24. The method of claim 23, further comprising providing positive pressure laminar air flow through the station to exclude contaminants.

25. The method of claim 23, further comprising precluding access to the enclosed platform from surroundings while the platform is accessible to an interior of the station.