Two-wafer loadlock wafer processing apparatus and loading and unloading method therefor

• US 6,042,623 A
• Filed: 01/12/1998
• Issued: 03/28/2000
• Est. Priority Date: 01/12/1998
• Status: Expired due to Term

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Edwards, Richard C.
• Primary Examiner(s): Graybill, David E.
• Application Number:
  US09/005,862
• Time in Patent Office: 806 Days
• Field of Search: 204/298.25, 204/298.26, 204/298.35, 438/908, 29/25.01
• US Class Current: 29/25.01
• CPC Class Codes: H01L 21/67751 vertical transfer of a single workpiece
• CPC Class Codes: H01L 21/67757 vertical transfer of a batch of workpieces
• CPC Class Codes: Y10S 414/137 including means for charging or discharging wafer cassette
• CPC Class Codes: Y10S 414/139 including wafer charging or discharging means for vacuum chamber
• CPC Class Codes: Y10S 438/908 Utilizing cluster apparatus

Abstract

Wafers from plural non-vacuum multiple wafer carriers are loaded and unloaded in an atmospheric front end of a wafer processing machine and transferred to and from a high vacuum chamber of a transfer module of a wafer processing cluster tool, or back end, through a single two-wafer loadlock. Preferably, with the wafers oriented horizontally throughout, two wafers are sequentially loaded into and simultaneously moved inbound to the high vacuum back end of the system, through one loadlock and sequentially moved into and simultaneously moved outbound through the same loadlock, the loadlock having a pair of water cooled supports for simultaneously actively cooling the two wafers. In both the atmospheric front end and vacuum back end environments, transfer arms load and unload the loadlock, and transfer wafers within the environments when all loadlocks are sealed. Preferably, two wafers are actively cooled in the loadlock. Preferably also, wafers are passed through a wafer aligner after being removed from a carrier and before placed in the loadlock. When two wafers are removed from the loadlock into the vacuum back end, one or two wafers may be temporarily held in a buffer position within the back end vacuum chamber.

Claims

1. A method of transferring wafers between multi-wafer carriers and a high vacuum environment of a transfer chamber of a wafer processing cluster tool, the method comprising the steps of:

positioning a first multi-wafer carrier in communication with a clean atmospheric environment adjacent to a robot transfer device that is located in an atmospheric front end of the tool;

then

successively transferring a first and a second wafer with the robot transfer device from the first carrier and into a two-wafer loadlock, operating as an inbound loadlock, that is open to the atmospheric environment and sealed from the high vacuum environment of the transfer chamber;

then

sealing the loadlock from the atmospheric environment;

then

pumping the loadlock to a vacuum pressure level;

then

opening the loadlock to the high vacuum environment of the transfer chamber;

then

successively removing the first and second wafers from the loadlock with a transfer arm located in the transfer chamber and placing the first and second wafers into one or more vacuum processing chambers when such chambers are in communication with the high vacuum environment; and

successively removing the first and second wafers, with the transfer arm located in the transfer chambers, from one or more vacuum processing chambers when such chambers are in communication with the high vacuum environment of the transfer chamber and placing the first and second wafers into a two-wafer loadlock, operating as an outbound loadlock, that is open to the high vacuum environment and sealed from the atmospheric environment of the front end of the tool;

then

sealing the outbound loadlock from the high vacuum environment of the transfer chamber;

then

venting the outbound loadlock to a pressure level of the atmospheric environment of the front end of the tool;

then

opening the outbound loadlock to the atmospheric environment of the front end;

then

successively transferring the first and second wafers from the outbound loadlock to a carrier.

2. The method of claim 1 wherein:

the two-wafer loadlock serving as an outbound loadlock is the same loadlock serving as the inbound loadlock; and

the steps of placing the first and second wafers into the two-wafer loadlock, sealing the outbound loadlock, venting the outbound loadlock, opening the outbound loadlock and transferring the first and second wafers from the outbound loadlock include the steps of so placing the wafers into, sealing, venting, opening and transferring the wafers from the same loadlock used as the inbound loadlock.

3. The method of claim 1 wherein:

the step of removing the wafers from the loadlock in the vacuum transfer chamber environment includes the steps of removing the first wafer from the loadlock to a holding position in the vacuum transfer chamber environment and then removing the second wafer from the loadlock.

4. The method of claim 1 further comprising the step of actively cooling wafers in the loadlock during the outbound loadlock venting step.

5. The method of claim 1 further comprising the steps of:

moving a wafer with the robot transfer device in the atmospheric front end environment and moving a wafer with the transfer arm in the high vacuum transfer chamber environment, both steps occurring when the loadlock is sealed to both the atmospheric front end environment and the high vacuum transfer chamber environment.

6. The method of claim 1 further comprising the steps of removing the first multi-wafer carrier from adjacent the robot transfer device in the atmospheric front end environment and replacing the first carrier with a second multi-wafer carrier by positioning the second carrier in communication with the atmospheric front end environment adjacent the robot transfer device, while wafers from a third carrier in communication with the atmospheric front end environment are being transferred to and from the loadlock by the robot transfer device.

7. The method of claim 1 wherein:

the steps of the process are performed with the wafers in a horizontal orientation;

the transfers of wafers into and the removal of wafers from the loadlock are carried out with substantially horizontal movements of the wafers; and

the method further includes the steps of moving the wafers vertically when within a loadlock.

8. The method of claim 1 wherein:

the steps of the process are performed with the wafers in a horizontal orientation;

the transfer of wafers into and the removal of wafers from the loadlocks and into and from the processing chambers, occurring in the high vacuum environment, are carried out with substantially horizontal movements of the wafers in a first horizontal plane;

the transfers of wafers into and the removal of wafers occurring in the atmospheric environment, from the loadlock, are carried out with substantially horizontal movements of the wafers in a second horizontal plane spaced vertically from the first horizontal plane; and

the method further includes the steps of moving the wafers vertically when within each of the loadlocks between the first and second horizontal planes.

9. The method of claim 1 wherein:

the step of transferring the wafers from the first carrier and into the loadlock includes the step of transferring the wafer to and from an alignment station in the atmospheric environment.

10. A method of manufacturing a semiconductor wafer comprising the steps of:

positioning a first carrier in communication with a clean atmospheric environment adjacent a robot transfer device that is located in an atmospheric front end of a semiconductor wafer processing tool;

then

successively transferring two wafers with the robot transfer device from the first carrier and into a two-wafer loadlock that is open to the atmospheric front end environment and sealed from the high vacuum environment of the transfer chamber;

then

sealing the loadlock from the atmospheric front end environment;

then

pumping the loadlock to a vacuum pressure level;

then

opening the loadlock to the high vacuum transfer chamber environment;

then

successively removing the wafers from the loadlock with a transfer arm located in the transfer chamber and placing the wafers into vacuum processing chambers when such chambers are in communication with the high vacuum transfer chamber environment;

then

processing the wafers in the processing chambers;

then

successively removing the wafers with a transfer arm from the vacuum processing chambers when such chambers are in communication with the high vacuum transfer chamber environment and placing the wafers into the two-wafer loadlock when the loadlock is open to the high vacuum transfer chamber environment and sealed from the atmospheric front end environment;

then

sealing the loadlock from the high vacuum transfer chamber environment;

then

venting the loadlock to a pressure level approximating the atmospheric front end environment;

then

opening the loadlock to the atmospheric front end environment;

then

successively transferring the wafers from the loadlock to the carrier with the robot transfer device in the atmospheric front end of the load.

11. A high vacuum wafer processing apparatus comprising:

a plurality of vacuum processing chambers each having a port therein for loading and unloading wafers individually therethrough;

a high vacuum transfer chamber having a plurality of ports in communication with the ports of the processing chambers;

an atmospheric front end chamber in communication with an ambient atmospheric pressure environment and having at least one non-vacuum carrier loading and unloading station;

a two-wafer loadlock chamber forming an access chamber between the high vacuum transfer chamber and the atmospheric front end chamber, the loadlock having two and not more than two wafer supports therein and thereby being configured to hold up to two wafers therein and not more than two wafers therein, a pump connected thereto to lower the pressure in the loadlock to a vacuum pressure level of the high vacuum transfer chamber and a vent connected to the ambient atmospheric pressure environment to raise the pressure of the loadlock to that of the atmospheric front end chamber;

the loadlock being operable when the high vacuum transfer chamber is at high vacuum and the atmospheric front end chamber is at ambient atmospheric pressure, having a vacuum side closure selectively openable to connect the loadlock chamber and the high vacuum transfer chamber and having an atmospheric side closure selectively openable to connect the loadlock and the atmospheric front end chamber at ambient atmospheric pressure;

a transfer arm in the high vacuum transfer chamber having a single wafer engaging element thereon moveable to and from each of the processing chambers and loadlock to successively transfer individual wafers thereamong; and

an individual wafer transfer device in the front end chamber moveable among the loadlock and the at least one carrier to successively transfer individual wafers thereamong.

12. The apparatus of claim 11 further comprising:

a wafer aligner in the front end chamber;

the wafer transfer device being also moveable to and from the wafer aligner.

13. The apparatus of claim 11 further comprising:

two wafer coolers in the loadlock situated to transfer heat from the two wafers to their respective wafer coolers during venting of the loadlock.

14. The apparatus of claim 13 wherein:

the loadlock includes two upwardly facing wafer support surfaces each having a respective one of the wafer coolers therein; and

the wafer supports each including a set of at least three lift pins having a raised position whereat a wafer is situated for handoff between the respective support and the transfer arm or the transfer device and a lowered position whereat a wafer is in contact with its respective support surface.

15. The apparatus of claim 11 wherein:

the loadlock includes a wafer elevator moveable between a vacuum transfer position and an atmospheric transfer position; and

the transfer arm, the ports of the processing chambers and the vacuum transfer position of the loadlock are located in a common horizontal plane.

16. The apparatus of claim 11 wherein:

the loadlock includes a wafer elevator moveable vertically between a vacuum transfer position and an atmospheric transfer position; and

the transfer device is horizontally moveable in a horizontal plane that contains the atmospheric transfer position of the loadlock.

17. The apparatus of claim 11 wherein:

the loadlock includes a wafer elevator moveable between a vacuum transfer position and an atmospheric transfer position;

the transfer arm, the ports of the processing chambers and the vacuum transfer position of the loadlock are located in a first horizontal plane; and

the transfer device is horizontally moveable in a second horizontal plane that contains the atmospheric transfer positions of the loadlock.

18. The apparatus of claim 17 wherein:

the carrier has a plurality of wafer storage positions vertically spaced in a vertical stack therein;

the carrier stations each include a carrier elevator operable to move a selected one of the plurality of wafer storage positions into the second horizontal plane; and

the transfer device is horizontally moveable in the second horizontal plane between the atmospheric transfer position of the loadlock and the selected one of the storage positions.

19. The apparatus of claim 17 wherein:

the carrier has a plurality of wafer storage positions vertically spaced in a vertical stack therein;

the transfer device being vertically moveable between the second horizontal plane to the level of a selected one of the storage positions.

20. The apparatus of claim 11 wherein:

the loadlock chamber, when closed to the atmospheric front end and high vacuum transfer chambers, encloses an evacuable volume therein substantially smaller than the volume required to contain a multiple wafer carrier.

21. The apparatus of claim 11 wherein:

the two-wafer loadlock chamber is configured to support a wafer in spaced parallel wafer support planes with the closures thereof configured for the transfer of wafers into and out of the chamber thereof in a direction perpendicular to the wafer support planes, whereby, when the wafer support planes are horizontal, the loadlock chamber is an over-under loadlock.

22. The apparatus of claim 11 wherein:

the apparatus includes a high vacuum back end section that includes the plurality of vacuum processing chambers and the high vacuum transfer chamber bounded by walls separating the vacuum environment within the back end section from an external environment; and

the loadlock chamber is mounted in a wall of the back end section with one closure thereof on the vacuum environment side of the wall and one closure on the side of the wall opposite the vacuum environment.