Cutting method for thick metal layer of wafer cutting channel

Abstract

The invention relates to the technical field of wafer processing, in particular to a cutting method for a thick metal layer of a wafer cutting channel. Comprising the following steps: S1, providing a wafer which comprises a metal layer and a silicon layer; s2, grinding and thinning the silicon layer of the wafer; s3, cutting is carried out from the surface of one side of the wafer along the cutting channel, and the silicon layer in the cutting channel is removed; and S4, performing laser processing on the cutting channel in the silicon layer, and processing the metal layer in the cutting channel until cutting is completed. Compared with the prior art, the surface of the wafer is prevented from being physically processed, the phenomenon of damage is prevented, and the burning risk is also reduced due to reduction of laser energy.

Description

Technical Field

[0001] The invention relates to the technical field of wafer processing, in particular to a method for cutting a thick metal layer of a wafer cutting path. Background Art

[0002] Existing wafer cutting methods mainly include DAG process and DBG process. Figure 2 As shown in the figure, the wafer is first thinned. Then laser cutting and cutting are performed. Figure 3 As shown, the wafer is first cut, and then film is attached and thinned.

[0003] However, the DBG process has completed the partial separation between individual wafers before grinding and thinning. As the thinning occurs during grinding, complete separation is achieved. Because the cutting depth of DBG will be higher than the target thickness, thinning will continue after the wafers are separated. If there are foreign objects in the cutting path at this time, making the thickness of some wafers too high, the grinding wheel teeth of the grinding equipment will collide with them, which may cause the surrounding wafers to be affected and collide.

[0004] For thin-film products, the DAG process is more difficult to process, and when the DBG process is used, the possibility of collision between individual wafers cannot be avoided. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for cutting a thick metal layer in a wafer cutting path.

[0006] To achieve the above purpose, a method for cutting a thick metal layer of a wafer cutting line is designed, comprising the following steps: S1, providing a wafer, including a metal layer and a silicon layer; S2, grinding and thinning the silicon layer of the wafer; S3, cutting along the cutting path from one side surface of the wafer to remove the silicon layer in the cutting path; S4, laser treatment is performed on the cutting path in the removed silicon layer, and the metal layer in the cutting path is processed until the cutting is completed.

[0007] The thickness of the wafer is less than 70um, wherein the thickness of the metal layer is 15-26um, and the thickness of the silicon layer is 20-50um.

[0008] In the step S4, the laser parameters are 2-5 passes and the power is 2-4W.

[0009] In the step S1, a protective film layer is attached to the metal layer side of the wafer.

[0010] In the step S4, the protective film layer is stretched before laser irradiation.

[0011] During the cutting in step S3, the wafer is not provided with the iron ring and the DAF, the protective film layer is in contact with the processing platform, the protective film layer is not removed at this time, and the cutting equipment cuts from the silicon layer.

[0012] Compared with the prior art, the present invention avoids physical processing of the wafer surface and prevents the occurrence of damage. The reduction of laser energy also reduces the risk of burning. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the process of the present invention.

[0014] Figure 2 The figure is a schematic diagram of the process of the DAG process before improvement according to the present invention.

[0015] Figure 3 This is a flow chart of the DBG process before improvement according to the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the accompanying drawings. Example

[0017] like Figure 1 As shown, the method for cutting a thick metal layer in a wafer cutting lane in this embodiment includes the following steps: S1, providing a wafer 1, including a metal layer 1-1 and a silicon layer 1-2; S2, grinding and thinning the silicon layer 1-2 of the wafer 1; S3, the cutting device 3 cuts along the cutting path from one side surface of the wafer 1 to remove the silicon layer 1-2 in the cutting path; S4, laser treatment is performed on the cutting path within the removed silicon layer 1-2, and the metal layer 1-1 within the cutting path is processed until the cutting is completed.

[0018] The thickness of the wafer 1 applicable to this embodiment is less than 70 um, wherein the thickness of the metal layer 1 - 1 is 15-26 um, and the thickness of the silicon layer 1 - 2 is 20-50 um.

[0019] During the laser irradiation in step S4, the laser parameters are 2-5 passes and the power is 2-4 W. In this embodiment, since the silicon layer of the cutting path has been removed, the parameters of the laser 4 need to be changed accordingly to prevent the protective film layer 2 from being penetrated by laser.

[0020] In step S1, a protective film layer 2 is attached to one side of the metal layer 1-1 of the wafer 1. And in step S4, the protective film layer 2 is stretched before laser irradiation. The protective film layer 2 has a certain tension to maintain the horizontality of the wafer 1 and avoid deformation or breakage of the wafer 1 during the laser irradiation.

[0021] When cutting in step S3, the wafer 1 is not provided with the iron ring and the DAF, the protective film layer 2 is in contact with the processing platform, and the protective film layer 2 is not removed at this time, and the cutting equipment cuts from the silicon layer 1-2 surface. The cutting height is the total thickness minus the thickness of the metal layer 1-1 and the thickness of the protective film layer 2.

[0022] In this embodiment, during grinding and thinning, the individual wafers are not separated from each other and do not collide with each other. The overall wafer and the laser do not cause the product to be squeezed. The individual wafers are not subjected to other forces and do not cause the individual wafers to be displaced and collide with other wafers. The protective film layer 2 also plays a role in fixing the individual wafers.

[0023] The existing DAG and DBG processes use a blade to cut the wafer surface, which is a physical cutting process. This will cause impact on both sides of the cutting path, resulting in wafer damage and cracking.

[0024] In step S4 of this embodiment, laser cutting is used for the cutting path, which avoids the phenomenon that the two sides of the cutting path are damaged or cracked due to impact. In addition, the silicon layer 1-2 in the wafer cutting path has been removed, and the laser cutting only needs to cut the metal layer 1-1. The laser energy can also be reduced, which reduces the situation that a single wafer is burned due to excessive laser energy.

Claims

1. A method for cutting a thick metal layer in a wafer sawing line, characterized in that: The steps include: S1, providing a wafer (1), comprising a metal layer (1-1) and a silicon layer (1-2); S2, grinding and thinning the silicon layer (1-2) of the wafer (1); S3, cutting along a cutting path from one side surface of the wafer (1) to remove the silicon layer (1-2) within the cutting path; S4, performing laser treatment on the cutting path within the removed silicon layer (1-2), and processing the metal layer (1-1) within the cutting path until the cutting is completed.

2. A method for cutting a thick metal layer on a wafer cutting path according to claim 1, characterized in that: The thickness of the wafer (1) is less than 70 um, wherein the thickness of the metal layer (1-1) is 15-26 um, and the thickness of the silicon layer (1-2) is 20-50 um.

3. The method for cutting a thick metal layer on a wafer cutting path according to claim 1, characterized in that: In the step S4, the laser parameters are 2-5 passes and the power is 2-4W.

4. The method for cutting a thick metal layer on a wafer cutting path according to claim 1, characterized in that: In the step S1, a protective film layer (2) is attached to one side of the metal layer (1-1) of the wafer (1).

5. The method for cutting a thick metal layer on a wafer saw street according to claim 4, characterized in that: In the step S4, before laser irradiation, the protective film layer (2) is subjected to a stretching treatment.

6. The method for cutting a thick metal layer on a wafer saw street according to claim 4, characterized in that: During the cutting in step S3, the wafer (1) is not provided with the iron ring and the DAF, the protective film layer (2) is in contact with the processing platform, the protective film layer (2) is not removed, and the cutting device cuts from the silicon layer (1-2) surface.

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