	US 7,552,736 B2
	Process for wafer backside polymer removal with a ring of plasma under the wafer
Kenneth S. Collins, San Jose, Calif. (US); Hiroji Hanawa, Sunnyvale, Calif. (US); Andrew Nguyen, San Jose, Calif. (US); Ajit Balakrishna, Sunnyvale, Calif. (US); David Palagashvili, Mountain View, Calif. (US); James P. Cruse, Soquel, Calif. (US); Jennifer Y. Sun, Sunnyvale, Calif. (US); Valentin N. Todorov, Palo Alto, Calif. (US); Shahid Rauf, Pleasanton, Calif. (US); Kartik Ramaswamy, San Jose, Calif. (US); Gerhard M. Schneider, Mountain View, Calif. (US); Imad Yousif, San Jose, Calif. (US); and Martin Jeffrey Salinas, San Jose, Calif. (US)
Assigned to Applied Materials, Inc., Santa Clara, Calif. (US)
Filed on Mar. 14, 2007, as Appl. No. 11/685,775.
Claims priority of provisional application 60/898645, filed on Jan. 30, 2007.
Prior Publication US 2008/0179009 A1, Jul. 31, 2008
This patent is subject to a terminal disclaimer.
Int. Cl. C25F 1/00 (2006.01); C25F 3/30 (2006.01); C25F 5/00 (2006.01)

U.S. Cl. 134—1.1 [134/1.2]

10 Claims

1. A process for removing polymer from a backside of a workpiece, comprising:

supporting said workpiece on the backside in a vacuum chamber while leaving at least a peripheral annular portion of the backside exposed;

confining gas flow at the edge of said workpiece within a gap at the edge of said workpiece on the order of about 1% of the diameter of the chamber, said gap defining a boundary between an upper process zone containing said wafer front side and a lower process zone containing said wafer backside;

providing a polymer etch precursor gas underneath the backside edge of the workpiece and applying RF power to a region underlying the backside edge of the workpiece to generate a first plasma of polymer etch species concentrated in an annular ring concentric with and underneath the backside edge of the workpiece;

removing polymer etch species from said upper process zone, wherein removing polymer etch species from said upper process zone comprises generating a second plasma from a precursor gas of a scavenger of the polymer etch species, and introducing scavenger by-products from said second plasma into said upper process zone.