US 12,170,224 B2
Method of processing wafer
Shunsuke Teranishi, Tokyo (JP)
Assigned to DISCO CORPORATION, Tokyo (JP)
Filed by DISCO CORPORATION, Tokyo (JP)
Filed on Aug. 20, 2021, as Appl. No. 17/407,311.
Claims priority of application No. 2020-149340 (JP), filed on Sep. 4, 2020.
Prior Publication US 2022/0076999 A1, Mar. 10, 2022
Int. Cl. H01L 21/78 (2006.01); H01L 21/268 (2006.01); H01L 21/304 (2006.01)
CPC H01L 21/78 (2013.01) [H01L 21/304 (2013.01); H01L 21/268 (2013.01); H01L 21/3043 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of processing a wafer to produce chips therefrom, the wafer having on a face side thereof a plurality of projected dicing lines classified into two groups extending respectively in first directions and second directions transverse to the first directions and a plurality of chip areas demarcated by the projected dicing lines, wherein devices are formed respectively in the chip areas, the method comprising:
a groove forming step of forming grooves in the wafer to a depth equal to or larger than a desired thickness of the chips from the face side of the wafer along the projected dicing lines;
a separation initiating point forming step of positioning a focused spot of a laser beam having a wavelength transmittable through the wafer, at a depth in the wafer corresponding to a thickness of the chips from a reverse side of the wafer that is opposite the face side thereof, applying the laser beam to the wafer, with the devices thereon, while moving the focused spot and the wafer relatively to each other, thereby forming separation initiating points in the wafer that are parallel to the face side of the wafer and made up of modified layers and cracks extending from the modified layers in the wafer that define a separation layer; and
a chip peeling step of peeling off the chips from the wafer at the separation initiating points, wherein the separation layer forms a bottom surface of each of the chips peeled off during the chip peeling step.
 
15. A method of processing a wafer to produce chips therefrom, the wafer having on a face side thereof a plurality of projected dicing lines classified into two groups extending respectively in first directions and second directions transverse to the first directions and a plurality of chip areas demarcated by the projected dicing lines, comprising:
a groove forming step of forming grooves in the wafer to a depth equal to or larger than a desired thickness of the chips from the face side of the wafer along the projected dicing lines;
a separation initiating point forming step of positioning a focused spot of a laser beam having a wavelength transmittable through the wafer, at a depth in the wafer corresponding to a thickness of the chips from a reverse side of the wafer that is opposite the face side thereof, applying the laser beam to the wafer while moving the focused spot and the wafer relatively to each other, thereby forming separation initiating points in the wafer that are parallel to the face side of the wafer and made up of modified layers and cracks extending from the modified layers in the wafer; and
a chip peeling step of peeling off the chips from the wafer at the separation initiating points,
wherein:
the separation initiating point forming step includes applying the laser beam to the wafer while positioning the focused spot thereof at depths depending on at least two different thicknesses of chips respectively in the chip areas,
the groove forming step includes forming grooves in the wafer to a depth equal to or larger than the desired thickness of the chips respectively in the chip areas, and
the chip peeling step includes forming chips having at least two different thicknesses respectively in the chip areas.
 
16. A method of processing a wafer to produce chips therefrom, the wafer having on a face side thereof a plurality of projected dicing lines classified into two groups extending respectively in first directions and second directions transverse to the first directions and a plurality of chip areas demarcated by the projected dicing lines, the method comprising:
a groove forming step of forming grooves in the wafer to a depth equal to or larger than a desired thickness of the chips from the face side of the wafer along the projected dicing lines;
a separation initiating point forming step of positioning a focused spot of a laser beam having a wavelength transmittable through the wafer, at a depth in the wafer corresponding to a predetermined thickness of the chips from a reverse side of the wafer that is opposite the face side thereof, applying the laser beam to the wafer while moving the focused spot and the wafer relatively to each other, thereby forming separation initiating points in the wafer that are parallel to the face side of the wafer and made up of modified layers and cracks extending from the modified layers in the wafer; and
a chip peeling step of peeling off the chips from the wafer at the separation initiating points, wherein the chips peeled off during the peeling step are of the predetermined thickness without using a grinding apparatus.