Wiring-Free, Plumbing-Free, Cooled, Vacuum Chuck

• US 20080277885A1
• Filed: 05/08/2007
• Published: 11/13/2008
• Est. Priority Date: 05/08/2007
• Status: Active Grant

• Current Assignee: Meyer Burger (Germany) GmbH (Meyer Burger Technology AG)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Duff, David G., Eldershaw, Craig
• Granted Patent: US 7,954,449 B2
• Time in Patent Office: Days
• US Class Current: 279/3
• CPC Class Codes: B25B 11/005 Vacuum work holders
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/67173 in-line arrangement
• CPC Class Codes: H01L 21/67748 horizontal transfer of a single workpiece
• CPC Class Codes: H01L 21/6838 with gripping and holding devices using a vacuum; Bernoulli devices
• CPC Class Codes: H01L 31/1876 Particular processes or apparatus for batch treatment of the devices
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 279/11 Vacuum

Abstract

A solar cell production system utilizes self-contained vacuum chucks that hold and cool solar cell wafers during transport on a conveyor between processing stations during a fabrication process. Each self-contained vacuum chuck includes its own local vacuum pump and a closed-loop cooling system. After each wafer is processed, it is removed from its vacuum chuck, and the vacuum chuck is returned to the start of the production line by a second conveyor belt. In one embodiment, each vacuum chuck includes an inductive power supply that is inductively coupled to an external source to drive that vacuum chuck'"'"'s vacuum pump and cooling system. An optional battery is recharged by the inductive power supply, and is used to power the vacuum pump and cooling system during hand-off between adjacent processing stations.

Claims

1. A self-contained vacuum chuck for holding substrate during a fabrication process, said vacuum chuck comprising:

a chuck body;

a support structure disposed on the chuck body, the support structure including an upper wall having a support surface and defining a vacuum chamber that is disposed below the support surface, wherein the upper wall defines a plurality of inlet openings that communicate between the support surface and the vacuum chamber;

a vacuum pump mounted on the chuck body for generating a low pressure in the vacuum chamber;

a thermal control system including ducts disposed on the upper wall of the support structure below the support surface, and means mounted on the chuck body for passing a thermal control fluid through the ducts; and

a power supply mounted on the chuck body and coupled to the vacuum pump and the thermal control system, whereby the vacuum pump functions to generate said low pressure in the vacuum chamber and the thermal control system functions to regulate the environmental aspects of the support surface in response to energy drawn from the power supply.

2. The portable vacuum chuck of claim 1, further comprising an inductive recharger mounted on the chuck body for recharging the power supply using electrical energy transferred by inductive coupling from a source located outside the chuck body.

3. The portable vacuum chuck of claim 1, wherein the ducts are disposed in the vacuum chamber, and wherein the thermal control system comprises a heat exchanger and a pump for circulating a coolant in the coolant ducts.

4. The portable vacuum chuck of claim 1, wherein the ducts are either mounted on or integrally connected to the upper wall of the support structure.

5. A production system comprising:

means for loading a plurality of wafers onto a plurality of vacuum chucks, wherein each of the vacuum chucks includes a chuck body, a support structure disposed on the chuck body, the support structure including an upper wall having a support surface and defining a vacuum chamber that is disposed below the support surface, a vacuum pump mounted on the chuck body for generating a low pressure in the vacuum chamber, a thermal control system including ducts disposed on the upper wall of the support structure below the support surface, and a power supply mounted on the chuck body and coupled to the vacuum pump and the thermal control system, whereby the vacuum pump functions to generate said low pressure in the vacuum chamber and the thermal control system functions to regulate environmental aspects of the support surface in response to energy drawn from the power supply;

a plurality of processing stations; and

means for sequentially conveying the plurality of vacuum chucks between the plurality of processing stations.

6. The production system of claim 5, wherein said means for sequentially conveying comprises:

a first conveyor belt disposed to convey the plurality of vacuum chucks between said means for loading to said plurality of processing stations, and from said plurality of processing stations to a means for off-loading the wafers from the vacuum chucks, and

a second conveyor belt disposed to convey the plurality of vacuum chucks between said means for off-loading the wafers and said means for loading said wafers

7. The production system of claim 6, wherein said plurality of processing stations comprises:

an extrusion apparatus including means for forming a plurality of high-aspect ratio gridline structures on each said wafer such that gridline material and sacrificial material are co-extruded onto said each wafer in a manner that creates parallel, elongated extruded structures wherein the gridline material of each extruded structure includes a high-aspect ratio gridline structure, and the sacrificial material of said each structure forms associated first and second sacrificial material portions respectively disposed on opposing sides of the associated high-aspect ratio gridline, and

means for removing the first and second sacrificial material portions.

8. The production system of claim 5,

wherein each of the plurality of processing stations includes an associated power source, and

wherein the power supply of each vacuum chuck comprises inductive means for coupling to the power source when said each vacuum chuck is disposed adjacent to said each associated processing station such that power is transferred from said inductive means to said vacuum pump and said thermal control system.

9. The production system of claim 8, wherein the power supply of each vacuum chuck further comprises means for supplying power to said vacuum pump and said thermal control system when said each vacuum chuck is disposed between said plurality of processing stations.

10. The production system of claim 5, wherein the ducts of each vacuum chuck are disposed in the vacuum chamber, and wherein the thermal control system of said each vacuum chuck comprises a heat exchanger and a pump for circulating a coolant in the ducts.

11. The production system of claim 5, wherein the ducts are disposed in the vacuum chamber, and wherein the thermal control system comprises means for circulating a fluid in the ducts.

12. A method for producing solar cells, the method comprising:

loading each of a plurality of wafers onto a corresponding vacuum chuck of a plurality of vacuum chucks, wherein each of the vacuum chucks includes a chuck body, a support structure disposed on the chuck body, the support structure including an upper wall having a support surface and defining a vacuum chamber that is disposed below the support surface, a vacuum pump mounted on the chuck body for generating a low pressure in the vacuum chamber, a cooling system including coolant ducts disposed on the upper wall of the support structure below the support surface, and a power supply mounted on the chuck body and coupled to the vacuum pump and the cooling system, whereby the vacuum pump functions to generate said low pressure in the vacuum chamber and the cooling system functions to cool the support surface in response to energy drawn from the power supply;

sequentially transferring each of the plurality of vacuum chucks through a plurality of processing stations including;

an extrusion apparatus including means for forming a plurality of high-aspect ratio gridline structures on each said wafer such that gridline material and sacrificial material are co-extruded onto said each wafer in a manner that creates parallel, elongated extruded structures wherein the gridline material of each extruded structure includes a high-aspect ratio gridline structure, and the sacrificial material of said each structure forms associated first and second sacrificial material portions respectively disposed on opposing sides of the associated high-aspect ratio gridline, and

means for removing the first and second sacrificial material portions.

13. The method of claim 12, wherein sequentially conveying comprises:

conveying each of the plurality of vacuum chucks and associated wafers on a first conveyor belt between a wafer loading apparatus to said plurality of processing stations, and from said plurality of processing stations to a wafer off-loading apparatus, and

conveying each of the plurality of vacuum chucks on a second conveyor belt between said wafer off-loading apparatus and said means wafer loading apparatus.

14. The method of claim 12,

wherein each of the plurality of processing stations includes an associated power source, and

wherein sequentially transferring each of the plurality of vacuum chucks comprises inductively coupling a power supply of each of said vacuum chucks to said associated power source as said each vacuum chuck passes through said associated processing station, whereby power is transferred from said power supply to said vacuum pump and said cooling system from said power source.

15. The method of claim 12, further comprising supplying power to said vacuum pump and said cooling system from a battery provided on said each vacuum chuck when said each vacuum chuck is disposed between said plurality of processing stations.