WAFER PROCESSING METHOD

• US 20190311951A1
• Filed: 04/04/2019
• Published: 10/10/2019
• Est. Priority Date: 04/09/2018
• Status: Active Grant

• Current Assignee: Disco Corporation
• Original Assignee: Disco Corporation
• Inventors: NISHIDA, Yoshiteru, IIDA, Hidekazu, YOKOO, Susumu, TAKAHASHI, Hiroyuki, CHITO, Kenta
• Granted Patent: US 10,790,192 B2
• Time in Patent Office: Days
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/02 Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
• CPC Class Codes: B23K 26/0622 by shaping pulses
• CPC Class Codes: B23K 26/351 for trimming or tuning of electrical components
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: H01L 21/02013 Grinding, lapping
• CPC Class Codes: H01L 21/304 Mechanical treatment, e.g. grinding, polishing, cutting H01L21/30625 takes precedence
• CPC Class Codes: H01L 21/30625 With simultaneous mechanical treatment, e.g. mechanico-chemical polishing
• CPC Class Codes: H01L 21/3065 Plasma etching; Reactive-ion etching
• CPC Class Codes: H01L 21/3221 of silicon bodies, e.g. for gettering
• CPC Class Codes: H01L 21/67092 Apparatus for mechanical treatment or grinding or cutting, see the relevant groups in subclasses B24B or B28D
• CPC Class Codes: H01L 21/6838 with gripping and holding devices using a vacuum; Bernoulli devices
• CPC Class Codes: H01L 21/78 with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304

Abstract

A method for processing a wafer in which patterns including a metal layer are formed on streets. The method includes: a step of applying a laser beam along the streets formed with the patterns to form laser processed grooves while removing the patterns; a step of forming cut grooves having a depth in excess of a finished thickness of the wafer, inside the laser processed grooves; a step of grinding the back surface side of the wafer to thin the wafer to the finished thickness and to expose the cut grooves to the back surface of the wafer, thereby dividing the wafer into a plurality of device chips; a step of removing a crushed layer formed on the back surface side of the wafer; and a step of forming a strain layer on the back surface side of the wafer by plasma processing using an inert gas.

Claims

1. A method for processing a wafer in which devices are formed respectively in regions on a front surface side partitioned by a plurality of streets and in which patterns including a metal layer are formed on the streets, the method comprising:

a laser processing step of applying a laser beam of such a wavelength as to be absorbed in the wafer along the streets formed with the patterns, to form laser processed grooves while removing the patterns;

a cut groove forming step of forming cut grooves having a depth in excess of a finished thickness of the wafer, inside the laser processed grooves, by a cutting blade thinner than a width of the laser processed grooves;

a protective member adhering step of adhering a protective member to the front surface side of the wafer formed with the cut grooves;

a grinding step of holding the wafer by a chuck table through the protective member, grinding a back surface side of the wafer to thin the wafer to the finished thickness, and to expose the cut grooves to the back surface of the wafer, thereby dividing the wafer into a plurality of device chips;

a crushed layer removing step of removing a crushed layer formed on the back surface side of the wafer by the grinding of the wafer; and

a strain layer forming step of forming a strain layer on the back surface side of the wafer deprived of the crushed layer, by plasma processing using an inert gas.

2. The method for processing a wafer according to claim 1, wherein in the crushed layer removing step, the crushed layer is removed by polishing with a polishing pad.

3. The method for processing a wafer according to claim 1, wherein in the crushed layer removing step, the crushed layer is removed by plasma etching using a halogen-containing gas.

4. The method for processing a wafer according to claim 1, further comprising:

a protective film forming step of forming a water-soluble protective film on the front surface side of the wafer before the laser processing step, and a protective film removing step of removing the protective film from the front surface side of the wafer after the laser processing step.