Method and apparatus for loading a batch of wafers into a wafer boat

• US 20040197174A1
• Filed: 04/02/2003
• Published: 10/07/2004
• Est. Priority Date: 04/02/2003
• Status: Active Grant

• Current Assignee: ASM International NV
• Original Assignee: ASM International NV
• Inventors: Van Den Berg, Jannes Remco
• Granted Patent: US 7,033,126 B2
• Time in Patent Office: Days
• US Class Current: 414/404
• CPC Class Codes: H01L 21/67781 Batch transfer of wafers
• CPC Class Codes: Y10S 414/137 including means for charging or discharging wafer cassette
• CPC Class Codes: Y10S 414/141 includes means for gripping wafer

Abstract

A receiver frame loads and unloads a batch of semiconductor wafers onto wafer holders in a wafer boat. The wafer holders extends continuously about the perimeter of an overlying wafer. The receiver frame is provided with a plurality of supporting arms which are immovably mounted to a vertically extending structure. The supporting arms are coaxially aligned and vertically spaced in a manner corresponding with the spacing of the wafer holders in the wafer boat. Each supporting arm is configured to be accommodated below a support ring, with its distal end extending to align with the center region of the wafer holder. The distal end of each supporting arm is provided with at least three support pins to support a wafer vertically spaced above a wafer holder. To load wafers onto the wafer holders, after placing the wafers upon the support pins, the wafer holders are moved above the support pins so that the wafer holders contact and lift the wafers off the support pins.

Claims

1. A system for transferring a plurality of semiconductor wafers, comprising:

a vertical wafer boat;

a plurality of wafer holders in the wafer boat, wherein the wafer holders are vertically spaced apart and wherein each wafer holder is configured to extend continuously around a perimeter of one of the plurality of wafers when the wafer is seated upon the wafer holder;

a wafer handler provided with an end effector;

a receiver frame independent of the wafer handler, wherein the receiver frame comprises a plurality of vertically spaced and coaxially aligned supporting arms, wherein each of the supporting arms comprises a wafer support structure, the wafer support structure configured to support one of the plurality of wafers while vertically spacing the wafer from one of the plurality of wafer holders directly below the wafer, wherein a height and spatial arrangement of the wafer support structure is sufficient to allow the end effector to contact a bottom surface of the wafer without the end effector contacting the wafer holder or the wafer support structure; and

a transfer mechanism, the transfer mechanism capable of moving the wafer boat and the receiver frame relative to each other from a spaced-apart position to a wafer transfer position,

wherein each supporting arm, including its wafer support structure, is sized and vertically spaced from other supporting arms such that the plurality of supporting arms can be accommodated between the plurality of wafer holders, each supporting arm accommodated directly below a wafer holder.

2. The system of claim 1, wherein the wafer support structures substantially coaxially align with the plurality of wafer holders when the wafer boat is positioned at the wafer transfer position.

3. The system of claim 1, wherein the wafer support structure of each supporting arm comprises at least three pins.

4. The system of claim 1, wherein each of the plurality of wafer holders is a plate.

5. The system of claim 4, wherein the plate comprises at least three openings, the three openings allowing vertical passage of the wafer support structure.

6. The system of claim 1, wherein a shape of each of the plurality of wafer holders from a top view is a ring.

7. The system of claim 6, wherein each ring comprises at least one opening, the at least one opening allowing vertical passage of the wafer support structure of each of the supporting arms.

8. The system of claim 1, wherein the wafer boat comprises a vertical extension, the vertical extension extending the height of the wafer boat.

9. The system of claim 8, wherein the vertical extension comprises at least three rods.

10. The system of claim 9, wherein each of the at least three rods comprises a upwardly facing surface for supporting one of the plurality of wafer holders.

11. The system of claim 1, wherein the upwardly facing surface is a recess in the rod.

12. The system of claim 1, wherein the supporting arms are directly fixed to a vertically extending structure.

13. The system of claim 12, wherein the receiver frame is immovably mounted on a vertically extending surface.

14. The system of claim 13, wherein the vertically extending surface is a wall of a transfer chamber.

15. The system of claim 1, wherein the receiver frame is immovable horizontally and wherein the transfer mechanism is configured to move the wafer boat vertically and horizontally.

16. The system of claim 1, further comprising a wafer transfer chamber configured for transferring wafers from a wafer cassette to the wafer boat, wherein the wafer transfer position is located in the wafer transfer chamber.

17. The system of claim 16, further comprising a process chamber for subjecting wafers to semiconductor fabrication processes, wherein the process chamber is adjacent to the wafer transfer chamber and wherein the spaced-apart position comprises the wafer boat located in the process chamber and the receiver frame located in the wafer transfer chamber.

18. An apparatus for transferring a plurality of semiconductor wafers to a wafer boat having a plurality of wafer holders, comprising:

a vertically extending structure;

a plurality of horizontally extending supporting arms attached to the vertically extending structure, wherein the supporting arms are sized and vertically spaced to fit between adjacent wafer holders in the wafer boat and wherein each of the plurality of supporting arms is immovable relative to other of the plurality of supporting arms and wherein each of the supporting arms is provided with a wafer support structure extending upwardly from the support arm and capable of extending upwardly through a central region of a directly overlying wafer holder and capable of supporting a wafer directly above the wafer holder while extending upwardly through the central region.

19. The apparatus of claim 18, wherein the vertically extending structure is a vertically extending rectangular plate.

20. The apparatus of claim 19, wherein each of the supporting arms comprises a horizontally extending rectangular plate.

21. The apparatus of claim 20, wherein each of the supporting arms wafer support structures comprises three pins.

22. A method of transferring semiconductor wafers between a wafer container and a wafer boat, comprising:

providing a wafer boat having a plurality of wafer holders for supporting wafers during semiconductor processing;

providing a receiver frame having a plurality of supporting arms, each supporting arm immovable relative to other of the plurality of supporting arms and provided proximate its distal end with a wafer support structure, the wafer support structure configured to allow a wafer supported by the wafer support structure to be contacted by an end effector at a bottom surface of the wafer without the end effector contacting the wafer support structure or any of the plurality of wafer holders;

horizontally moving the wafer boat and the receiver frame relative to each other to place each of the plurality of supporting arms between pairs of adjacent wafer holders and to approximately align the wafer support structures with a center of a directly overlying wafer holder;

positioning a top surface of the wafer support structure of each of the supporting arms above a wafer holder directly overlying the supporting arm;

placing a wafer from the wafer container onto one of the wafer support structures;

seating the wafer upon the wafer holder by vertically shifting the wafer boat and the receiver frame relative to each other; and

horizontally distancing the wafer boat from the receiver frame after lifting the wafer.

23. The method of claim 22, wherein seating the wafer comprises vertically lifting the wafer boat while the plurality of wafers remains stationary.

24. The method of claim 22, wherein horizontally moving the wafer boat comprises moving the wafer boat from a first chamber to a second chamber, the first chamber and the second chamber separated by a partition.

25. The method of claim 24, wherein the first chamber is a process chamber configured for subjecting wafers to semiconductor fabrication processes and the second chamber is a transfer chamber configured for transferring wafers to a wafer boat.

26. The method of claim 24, wherein horizontally distancing the wafer boat comprises moving the wafer boat from the second chamber to the first chamber.

27. The method of claim 22, wherein horizontally moving the wafer boat and horizontally distancing the wafer boat are performed using a single transfer mechanism.

28. A method of transferring semiconductor wafers, comprising:

providing at least two wafers in a wafer cassette;

providing at least two wafer holders in a wafer boat;

providing at least two horizontally extending arms;

providing a wafer handler;

horizontally inserting the arms into the wafer boat;

inserting each of the wafers into the wafer boat above one of the wafer holders using the wafer handler, wherein the wafer and the arms are each inserted into the wafer boat from a different direction relative to each other;

supporting each of the wafers above and vertically separated from the wafer holder with one of the arms after inserting each of the wafers; and

subsequently seating each of the wafers upon one of the wafer holders by simultaneously lowering each of the horizontally extending arms relative to the at least two wafer holders, wherein each of the wafer holders extends continuously around a perimeter of one of the wafers seated upon the wafer holder.

29. The method of claim 28, wherein simultaneously lowering each of the horizontally extending arms relative to the at least two wafer holders comprises vertically raising the at least two wafer holders while the at least two horizontally extending arms remains stationary.

30. The method of claim 28, wherein horizontally inserting the arms into the wafer boat comprises horizontally moving the wafer boat while the arms remain stationary.

31. A method of transferring a plurality of wafers onto a plurality of wafer holders in a vertical wafer boat, comprising:

positioning each of the plurality of wafers above one of the plurality of wafer holders;

supporting the plurality of wafers vertically separated from each of the plurality of wafer holders after positioning;

seating each of the plurality of wafers upon one of the plurality of wafer holders by raising the wafer boat, wherein each of the plurality of wafer holders supporting a wafer extends continuously around an outer edge of the wafer after seating.

32. The method of claim 31, wherein positioning each of the plurality of wafers comprises moving one wafer at a time to a position above one of the plurality of wafer holders.

33. The method of claim 31, further comprising horizontally moving the wafer boat before positioning each of the plurality of wafers.