# US 2019/0172749 A1 · Wafer processing method

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- Number: US 2019/0172749 A1
- Document ID: US20190172749A1
- Status: Published application
- Kind: A1
- Application number: 16/206,334
- Filed: 2018-11-30
- Published: 2019-06-06
- Earliest claimed: 2017-12-05
- Assignees: Disco Corporation
- Applicants: Disco Corporation
- Inventors: Kota FUKAYA; Chae Yong; Zhiwen CHEN
- Web page: https://patentgrep.com/patent/US20190172749A1

## CPC

- H10P 54/00: Cutting or separating of wafers, substrates or parts of devices
- B23K 26/0006: {taking account of the properties of the material involved (B23K26/32, B23K26/40 take precedence)}
- B23K 26/046: Automatically focusing the laser beam
- B23K 26/0624: {using ultrashort pulses, i.e. pulses of 1 ns or less}
- B23K 26/064: by means of optical elements, e.g. lenses, mirrors or prisms
- B23K 26/0853: {Devices involving movement of the workpiece in at least two axial directions, e.g. in a plane}
- B23K 26/53: for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
- H10W 46/00: Marks applied to devices, e.g. for alignment or identification
- B23K 2101/40: Semiconductor devices
- B23K 2103/54: {Glass}
- B23K 2103/56: {being semiconducting}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A wafer is divided along a plurality of division lines by applying a laser beam of such a wavelength as to be transmitted through the wafer, to form division start point modified layers along the division lines; and applying an external force to the wafer, to divide the wafer along the division lines, with the division start point modified layers as start points of division. Prior to forming the division start point modified layers on the back surface side of the wafer, the laser beam is applied at an output of not more than a first output, to form crack guide layers for guiding a crack extension direction as modified layers in the vicinity of the back surface. Thereafter the division start point modified layers are formed at positions equivalent to the positions of the crack guide layers.

## Claims

### Claim 1

A wafer processing method for processing a wafer on which a plurality of intersecting division lines are set, the wafer processing method comprising:
a modified layer forming step of applying a laser beam of such a wavelength as to be transmitted through the wafer to regions of the wafer corresponding to the division lines at a first output from a surface on one side of the wafer, with a focal point of the laser beam positioned inside the wafer, to form division start point modified layers inside the wafer; and
a dividing step of applying an external force to the wafer to divide the wafer along the division lines, with the division start point modified layers as start points of division, after the modified layer forming step is performed,
wherein the modified layer forming step includes
a first sub-step of applying the laser beam at an output of not more than the first output, to form crack guide layers for guiding a crack extension direction inside the wafer in a vicinity of the surface on the one side of the wafer, prior to the formation of the division start point modified layers, and
a second sub-step of applying the laser beam at the first output, with a focal point of the laser beam positioned at a position which is equivalent to the position of the crack guide layers or which is on the side of a surface on an other side opposite to the surface on the one side of the wafer as compared to the crack guide layers, to form the division start point modified layers and to form cracks communicating with the surface on the one side from the division start point modified layers, after the first sub-step is performed.