Dual-mask arrangement for solar cell fabrication

1. An arrangement for processing wafers in a vacuum processing system using masks, comprising:

a wafer carrier, configured for simultaneously supporting a plurality of wafers during processing inside the vacuum processing system, and comprising a carrier frame and two transport rails each provided on a corresponding edge of the carrier frame, the transport rails configured to transport the wafer carrier throughout the vacuum processing system;

a plurality of susceptors attached to the carrier frame, each susceptor configured to support a single wafer;

a plurality of inner masks, each configured for placing on top of one of the wafers supported by one of the susceptors, each inner mask having an opening-pattern to mask parts of the wafer and expose remaining parts of the wafer;

a plurality of outer masks, each configured for placing on top of a corresponding inner mask, each outer mask having an opening configured to partially cover the corresponding inner mask;

a mask frame configured to support and lift the plurality of inner masks and the plurality of outer masks off of the wafer carrier, and to secure the plurality of inner and outer masks to the respective susceptor.

2. The arrangement of claim 1 , wherein each of the inner masks consists of a flat metal sheet having the opening cut of size slightly smaller than the wafer, so that when the inner mask is placed on the wafer it covers peripheral edge of the wafer.

3. The arrangement of claim 2 , wherein each of the inner masks is made of steel.

4. The arrangement of claim 2 , wherein each of the inner mask has a thickness of 0.001 to 0.003 inches.

5. The arrangement of claim 1 , further comprising a plurality of magnets imbedded in each of the susceptors and configured to pull the respective inner mask into contact with the corresponding wafer.

6. The arrangement of claim 5 , wherein each of the outer masks is made of magnetic material for shunting the magnetic fields from the magnets and for keeping the outer mask in contact with the respective inner mask.

7. The arrangement of claim 5 , wherein the plurality of magnets are made of Samarium Cobalt.

8. The arrangement of claim 5 , wherein the magnets imbedded in each of the susceptors alternate N-S.

9. The arrangement of claim 1 , wherein each of the outer masks is made from aluminum and rests in physical contact on top of the respective inner mask.

10. The arrangement of claim 1 , wherein each of the susceptors comprises an electrostatic chuck.

11. The arrangement of claim 10 , wherein the carrier frame comprises ceramic bars holding the plurality of susceptors.

12. The arrangement of claim 10 , wherein the vacuum processing system comprises at least one reactive ion etch (RIE) chamber and the rails are configured for transporting the wafer carriers through the RIE chamber.

13. The arrangement of claim 10 , wherein the wafer carrier further comprises mask lifters configured for engaging the mask frame to thereby lift the outer and inner masks off of the wafer carrier.

14. The arrangement of claim 10 , wherein the wafer carrier further comprises wafer lift pins configured for lifting the wafers off of the susceptors.

15. The arrangement of claim 1 , wherein the outer and inner masks are configured to be held to the wafer carrier by magnetic forces only, so as to enable easy and fast loading and unloading of wafers.

16. The arrangement of claim 1 , wherein the each of the susceptors comprises a raised frame having a recess which defines a pocket below the wafer, such that the wafer is suspended above the pocket by the wafer's periphery resting on the recess.

17. The arrangement of claim 1 , wherein the wafer carrier comprises alignment pins and each of the outer masks has corresponding alignment recesses.

18. The arrangement of claim 1 , wherein each of the outer masks comprises a folded sheet of aluminum.

19. The arrangement of claim 1 , wherein each of the inner masks is sandwiched between the mask frame and the corresponding outer mask.