Vacuum processing system

• US 4,687,542 A
• Filed: 10/24/1985
• Issued: 08/18/1987
• Est. Priority Date: 10/24/1985
• Status: Expired due to Fees

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Matthews, Robert, Davis, Cecil J., Hildenbrand, Randall C.
• Primary Examiner(s): Bashore, S. Leon
• Assistant Examiner(s): Anderson, Andrew J.
• Application Number:
  US06/790,924
• Time in Patent Office: 663 Days
• Field of Search: 156/345, 156/643, 156/657, 156/662, 414/217, 414/222, 414/225, 414/411, 414/416, 414/422, 414/744 R, 118/729, 118/733, 118/50.1, 204/298
• US Class Current: 438/716
• CPC Class Codes: H01L 21/67201 characterized by the construction of the load-lock chamber
• CPC Class Codes: H01L 21/67748 horizontal transfer of a single workpiece
• CPC Class Codes: H01L 21/67772 involving removal of lid, door, cover
• CPC Class Codes: Y10S 414/136 including wafer orienting means
• CPC Class Codes: Y10S 414/137 including means for charging or discharging wafer cassette
• CPC Class Codes: Y10S 414/138 Wafers positioned vertically within cassette
• CPC Class Codes: Y10S 414/139 including wafer charging or discharging means for vacuum chamber
• CPC Class Codes: Y10S 414/141 includes means for gripping wafer

Abstract

A system for performing one semiconductor manufacturing operation or sequence of operations with reduced particulate contamination. A vacuum-tight wafer carrier, which contains numerous wafers in vacuum in a sealed box, is placed into a platform inside a vacuum load lock. The platform contains slots and protruding fingers to provide accurate registration of the position of the wafer carrier. After the load lock is pumped down, the door of the wafer carrier is opened, and a transfer arm removes wafers from the wafer carrier, in any desired order, and transfers them one by one through a port into a processing chamber.

Claims

1. A load lock comprising:

a chamber having a vacuum-sealable lid;

space within said chamber for a wafer carrier having a door; and

a door opener, positioned inside said load lock in proximity to said space for a wafer carrier,

whereby said door opener can open and close the door of the wafer carrier while said chamber is under vacuum.

2. The load lock of claim 1,

wherein said space within said chamber for a wafer carrier is defined by

a carrier position registration platform,

whereby the position of a wafer carrier at rest in said load lock is accurately and precisely known.

3. The load lock of claim 2, further comprising

a plurality of wafer carriers,

said wafer carriers each having vacuum sealed doors and being shaped to mate with said platform.

4. The load lock of claim 1,

wherein said load lock is connected near the bottom surface thereto to a vacuum exhaust manifold which is connected to a vacuum pump.

5. The load lock of claim 1, further comprising

pressure sensors connected to the interior of said load lock.

6. The load lock of claim 1, further comprising

particulate sensors connected to the interior of said load lock.

7. The load lock of claim 1, further comprising

position sensing switches,

said position sensing switches being located such that said position sensing switches will indicate if the door of a wafer carrier in said space in said load lock is fully open or if the door of a wafer carrier in said space in said load lock is fully closed.

8. The load lock of claim 1,

wherein the lid of said load lock further comprises a gas manifold therein,

whereby filtered gas can be applied to said manifold to blow off particulates from the exterior of one of said wafer carriers placed in said load lock.

9. A load lock comprising:

a chamber having a vacuum-sealable lid;

space within said chamber where a wafer carrier having a door and containing wafers of a predetermined diameter can be placed; and

an elevatable and extensible transfer arm,

said transfer arm containing support elements such that one of said wafers of said predetermined diameter can be supported by said transfer arm with edge contact only.

10. The load lock of claim 9,

wherein said transfer arm comprises along the periphery thereof a plurality of pins

having conically tapered upper portions

and spaced to support said wafers of said predetermined diameter.

11. The load lock of claim 9,

wherein said arm is elevatable but said wafer carrier is not elevatable while said load lock is under vacuum.

12. The load lock of claim 9, wherein said transfer arm has less than 1/10th of one inch total vertical thickness.

13. The load lock of claim 9 further comprising

an openable vacuum-tight port in the side of said load lock.

14. The load lock of claim 13,

wherein said openable port is positioned so that said transfer arm can be extended through said openable port while carrying a wafer.

15. The load lock station of claim 9,

wherein said transfer arm in said load lock has only two degrees of freedom.

16. The load lock of claim 9,

wherein said transfer arm is extensible in a straight line only, and also is elevatable.

17. The load lock of claim 9,

wherein said load lock is connected near the bottom surface thereof to a vacuum exhaust manifold which is connected to a vacuum pump.

18. The load lock of claim 17,

wherein said transfer arm is powered by motors located inside said exhaust manifold.

19. The load lock of claim 18,

wherein said transfer arm is mounted through a pivotal joint to a transfer arm support,

and said transfer arm support is pivotably mounted to a tubular support,

said tranfer arm and said arm support having approximately equal center-to-center distances,

and wherein said pivotal joint between said transfer arm and said transfer arm support is mechanically connected to provide differential rotation at twice the rate of differential rotation of said transfer arm support with respect to said tubular support.

20. The load lock of claim 19,

wherein said arm support is connected to a shaft which is connected to an arm drive motor mounted on an elevator stage.

21. The load lock of claim 17,

wherein said transfer arm is connected to an elevator stage inside said exhaust manifold,

and extension of said transfer arm is controlled by a motor which is also mounted on said elevator stage inside said exhaust manifold.

22. The load lock of claim 9,

wherein said transfer arm is mounted through a pivotal joint to a transfer arm support,

and said transfer arm support is pivotably mounted to a tubular support,

said transfer arm and said arm support having approximately equal center-to-center distances,

and wherein said pivotal joint between said transfer arm and said transfer arm support is mechanically connected to provide differential rotation at twice the rate of differential rotation of said transfer arm support with respect to said tubular support.

23. The load lock of claim 9, further comprising

pressure sensors connected to the interior of said load lock.

24. The load lock of claim 9, further comprising

particulate sensors connected to the interior of said load lock.

25. The load lock of claim 9,

wherein said transfer arm is elevatable to below the height of the door of the wafer carrier,

whereby said wafer carrier door can be opened with clearance above said transfer arm.

26. The load lock of claim 9, further comprising

a plurality of wafer carriers shaped to fit into said space inside said chamber,

wherein each said wafer carrier is adapted to support wafers face down therein using line contact and not using substantial area contact.

27. An integrated circuit processing station comprising:

a load lock comprising;

a chamber having a vacuum-sealable lid and also an openable vacuum-tight port;

space within said chamber where a wafer carrier containing wafers of a predetermined diameter can be placed; and

an elevatable and extensible transfer arm,

said transfer arm containing support elements such that one of said wafers of said predetermined diameter can be supported by said transfer arm with edge contact and not with substantial area contact;

a wafer stage in proximity to said port on the outside of said load lock chamber,

said wafer stage comprising a wafer support

positioned so that said transfer arm from said load lock can place a wafer on said wafer support and lower and retract to leave said wafer on said wafer support.

28. The integrated circuit processing station of claim 27,

wherein said wafer support provides line contact and not substantial area contact to the lower surface of a wafer placed thereon.

29. The processing station of claim 27,

wherein said transfer arm in said load lock has only two degrees of freedom.

30. A wafer transport system comprising:

a wafer carrier having slots for holding a plurality of wafers therein,

said wafer carrier also having a vacuum sealable door,

said wafer carrier also having a safety latch to hold said vacuum sealable door shut;

and a load lock, comprising

a chamber having a vacuum-sealable lid;

space within said chamber for a wafer carrier; and

a door opener, positioned inside said load lock in proximity to said space for a wafer carrier,

whereby said door opener can open and close the door of said wafer carrier while said load lock is under vacuum;

said load lock also comprising a finger for releasing said safety latch whenever said wafer carrier is placed in said wafer carrier space inside said load lock.

31. A wafer transport system, comprising:

a wafer carrier having slots for holding a plurality of wafers therein,

said wafer carrier also having a vacuum sealable door,

said wafer carrier also having a safety latch to hold said vacuum sealable door shut;

and a load lock, comprising

a chamber having a vacuum-sealable lid;

space within said chamber where a wafer carrier containing wafers of a predetermined diameter can be placed;

a door opener, positioned inside said load lock in proximity to said space for a wafer carrier,

whereby said door opener can open and close the door of said wafer carrier while said load lock is under vacuum;

and an elevatable and extensible transfer arm,

said transfer arm containing support elements such that one of said wafers of said predetermined diameter can be supported by said transfer arm with edge contact only;

said load lock also comprising a finger for releasing said safety latch whenever said wafer carrier is placed in said wafer carrier space inside said load lock.

32. A method for fabricating integrated circuits, comprising the steps of:

(a) providing a plurality of wafers in a wafer carrier box, said wafer carrier box having a vacuum sealable door;

(b) placing said wafer carrier box into a load lock attached to a process station,

said lock having a vacuum sealable lid;

(c) closing said lid and pumping down said load lock to a pressure less than 10 to the -4 Torr;

(d) opening said door of said wafer carrier and extending a transfer arm into said wafer carrier, to remove a selected one of said wafers therefrom;

(e) transferring wafers

in a desired sequence from said wafer carrier to said process station and back

by extending said transfer arm through a port between said load lock and said process station, and

(f) closing said door of said wafer carrier, closing said port in said adjacent processing chamber, and raising the pressure of said load lock to approximately atmospheric,

so that said wafers remain in vacuum inside said wafer carrier and said door of said wafer carrier is held closed by differential pressure; and

(g) removing said wafer carrier from said load lock.

33. The method of claim 32,

wherein said load lock comprises a door opener, positioned inside said load lock in proximity to a space for said wafer carrier,

whereby said door opener can perform said step (d) of opening the door of said wafer carrier, and said step (f) of closing the door of said carrier, while said load lock chamber is under vacuum.

34. The method of claim 32,

wherein said load lock comprises an elevatable and extensible transfer arm,

said transfer arm containing support elements such that one of said wafers of said predetermined diameter can be supported by said transfer arm with edge contact only,

said transferring wafers being performed at least partially by said transfer arm.

35. The method of claim 32,

wherein said wafer carrier supports said wafers with line contact and not by contact with any substantial area of the lower surface of said wafers.

36. The method of claim 32,

wherein the lid of said load lock further comprises a gas manifold therein,

and wherein filtered gas is supplied to said manifold to blow off particulates from the exterior of said wafer carrier after said carrier has been placed in said load lock.

37. The method of claim 32,

wherein said load lock further comprises first and second position sensing switches,

said transfer arm not being extended into said wafer carrier until said first position sensing switch indicates that the door of said wafer carrier is fully open,

and said load lock not being raised in pressure until said second position sensing switch indicates that the door of said wafer carrier is sufficiently closed to effect a vacuum seal.

38. The method of claim 32,

wherein said transfer arm is extensible only in a straight line, and also is elevatable.

39. The method of claim 32,

wherein, in said transferring step, said arm is elevated to access a desired wafer location in said wafer carrier while said wafer carrier is held fixed.

40. The method of claim 32,

wherein said transfer arm in said load lock has only two degrees of freedom.

41. The method of claim 32,

wherein said transfer arm has less than 1/10th of one inch total vertical thickness.

42. The method of claim 32,

wherein said space within said chamber for a wafer carrier is defined by

a carrier position registration platform in said load lock chamber,

whereby the position of one of said wafer carriers when at rest in said load lock is accurately and precisely known.