US 12,354,916 B2
Method of processing wafer
Hayato Iga, Tokyo (JP); Kazuya Hirata, Tokyo (JP); and Shunichiro Hirosawa, Tokyo (JP)
Assigned to DISCO CORPORATION, Tokyo (JP)
Filed by DISCO CORPORATION, Tokyo (JP)
Filed on Aug. 15, 2022, as Appl. No. 17/819,660.
Claims priority of application No. 2021-132212 (JP), filed on Aug. 16, 2021.
Prior Publication US 2023/0050807 A1, Feb. 16, 2023
Int. Cl. H01L 21/78 (2006.01); H01L 21/268 (2006.01); H01L 21/304 (2006.01)
CPC H01L 21/78 (2013.01) [H01L 21/268 (2013.01); H01L 21/304 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A method of processing a first wafer having a plurality of devices formed on a face side thereof and a beveled outer circumferential region, by applying a laser beam to the first wafer to form a peel-off layer in the first wafer and thereafter dividing the first wafer along the peel-off layer that functions as a division initiating point, the method comprising:
an affixing step of affixing the face side of the first wafer to a face side of a second wafer;
a first peel-off layer forming step of applying the laser beam to a region of the first wafer that is positioned radially inwardly of the outer circumferential region of the first wafer, in such a manner that a focused spot of the laser beam is progressively closer to the face side of the first wafer as the focused spot is progressively closer to the outer circumferential region, thereby forming a first peel-off layer in the first wafer that extends along a side surface of a truncated cone having a first bottom surface positioned near the face side of the first wafer and a second bottom surface positioned within the first wafer and smaller in diameter than the first bottom surface;
a second peel-off layer forming step of applying the laser beam to a region of the first wafer that is positioned radially inwardly of the first peel-off layer while the focused spot of the laser beam is being positioned on the second bottom surface of the truncated cone, thereby forming a second peel-off layer in the first wafer that extends along the second bottom surface of the truncated cone; and
a dividing step of, after the affixing step, the first peel-off layer forming step, and the second peel-off layer forming step, exerting external forces on the first wafer thicknesswise of the first wafer to divide the first wafer along the first peel-off layer and the second peel-off layer that function as division initiating points.