Wafer edge metal residue removing method

Abstract

The invention discloses a method for removing metal residues on the edge of a wafer in the technical field of wafer processing. The method for removing the metal residues on the edge of the wafer comprises the following steps that a scribing film is attached to the wafer according to needs; a to-be-processed wafer is loaded into a cutting machine table, a machining platform rotates by one circle with the center point of the wafer as the center axis, and cutting of one circle of the edge of the wafer is completed; according to the processing scheme for removing the metal residues on the edge of the wafer, the annularly-cut wafer is placed on a processing platform, a scribing film for fixing the wafer is manually torn off, cut waste materials are automatically separated from the wafer, processing is completed, whether the metal residues exist on the edge of the wafer or not is determined before annular cutting, and the necessity of removing operation is determined. The wafer is pretreated and metal remaining on the surface of the edge is removed through the ring cutting function of the cutting equipment, and the situation that when the wafer is cut and separated in the later procedure, a cutting blade makes contact with the metal on the edge, so that the blade is contaminated and damaged, and the quality of a machined object is affected is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of wafer processing, and in particular to a method for removing metal residues at the edge of a wafer. Background Art

[0002] In semiconductor packaging manufacturing, the entire wafer is usually cut and separated into individual crystals. The crystals are generally arranged in a "T-shaped" pattern, and there are groove-shaped connection areas between the crystals, which are usually called cutting paths.

[0003] The above-mentioned cutting paths are mainly composed of SiO2, SiOC, GaAs and other media, which are high-hardness brittle materials. The industry uses diamond blades to cut them, which can meet higher processing quality requirements. When the diamond blade is used to grind and cut the brittle semiconductor material, the diamond particles exposed on the surface of the blade can effectively grind it into particles and ensure the flatness of the grain edge. Diamond blade cutting is essentially the grinding of the workpiece, which is a material removal processing method. When the blade rotates at high speed, the diamond particles on the surface rub against the workpiece, so that the workpiece is ground into particles and discharged under the action of water flow.

[0004] During the metal bump forming process, the wafer will go through processes such as sputtering, electroplating, and etching. Generally, the edges of the wafer will be protected during processing. However, due to insufficient equipment precision and improper fixture maintenance, the electroplating solution sometimes penetrates into the edge area of ​​the wafer during the process and forms a metal covering layer.

[0005] Copper, titanium and other metals attached to the edge of the wafer are relatively soft, and sometimes adhere to the surface of the cutting blade when the wafer is cut, covering the diamond particles. In this way, the diamond on the surface of the cutting blade cannot effectively play its grinding role, resulting in abnormalities in the quality of the cut product, such as edge collapse and defects of the grain edge. The edge collapse and defects of the chip caused by the abnormal cutting blade often lead to the failure of the chip function. Summary of the invention

[0006] The purpose of the present invention is to provide a method for removing metal residues from the edge of a wafer, so as to solve the problem that the diamond on the surface of the cutting blade proposed in the above-mentioned background technology cannot effectively play its grinding role, resulting in abnormal quality of the cutting processing products, such as edge collapse and defects of the grains. The edge collapse and defects of the chip caused by the abnormal cutting blade often lead to the failure of the chip function.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for removing metal residues at the edge of a wafer, the method comprising the following steps:

[0008] S1: Attach dicing film to the wafer as needed;

[0009] S2: The wafer to be processed is loaded onto the cutting machine, and the processing platform rotates one circle around the center point of the wafer as the central axis to complete the cutting of a circle around the edge of the wafer;

[0010] S3: Place the ring-cut wafer on the processing platform, manually tear off the dicing film that fixes the wafer, and automatically separate the cut waste from the wafer to complete the processing.

[0011] Preferably, in step S2, whether there is any metal residue on the edge of the wafer before ring cutting is performed to confirm the necessity of the removal operation.

[0012] Preferably, in step S2, the cutting blade used by the cutting machine is a high-strength wide-edge diamond blade.

[0013] Preferably, in step S3, the wafer is debonded by ultraviolet light before the film is manually peeled off to complete the film peeling operation.

[0014] Preferably, step S1 includes the following specific steps:

[0015] A1: Place the wafer to be processed under the tool microscope, measure the radial width W of the metal residue at the edge of the wafer, and record the data;

[0016] A2: The wafer is filmed and the dicing film is attached to the wafer. After filming, the wafer, dicing film and dicing ring form a device that can be processed by the cutting equipment.

[0017] Preferably, step S2 includes the following specific steps:

[0018] B1: Load the device that can be processed by the cutting equipment in step A2 onto the equipment processing platform, clamp the dicing ring with the clamp on the edge of the platform, and fix the processing object with vacuum adsorption on the platform. The cutting equipment has a micro camera unit, through which the processing device is positioned and the cutting effect is observed;

[0019] B2: Use the Edge Teach function of the device to perform edge search on the processed wafer and save the information in the device host at the same time;

[0020] B3: Enter the cutting depth and blade speed information into the program according to the job requirements;

[0021] B4: Enter the metal residual radial width W data measured in step A1 into the program;

[0022] B5: The high-speed rotating blade is set according to the above program. It descends to the set height in the chip invalid area inside the edge of the wafer. The platform starts to rotate slowly with the wafer until a circle of cutting is completed;

[0023] B6: After cutting, the workpiece is sent to the cleaning table, where it is cleaned and dried before being sent out of the machine.

[0024] Preferably, step S3 includes the following specific steps:

[0025] C1: Place the cut product with its back facing up on a flat rubber platform;

[0026] C2: Peel off the dicing film along the edge, slowly separate the film from the wafer, and separate the waste from the wafer.

[0027] Compared with the prior art, the beneficial effects of the present invention are: this processing scheme for removing metal residues on the edge of the wafer utilizes the circular cutting function of the cutting equipment to pre-treat the wafer and remove the metal remaining on the edge surface, thereby preventing the cutting blade from contacting the edge metal when the wafer is cut and separated in the subsequent process, causing the blade to be contaminated and damaged, thereby affecting the quality of the processed product. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a wafer with metal residue covering the edge of the present invention;

[0029] Figure 2 It is a schematic diagram of the processing flow of the present invention;

[0030] Figure 3 It is a schematic diagram of the structure of the wafer cutting equipment of the present invention;

[0031] Figure 4 This is a schematic diagram of the working screen during the ring cutting metal removal of the present invention;

[0032] Figure 5 It is a schematic diagram of the Dicing film tearing operation during waste removal of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The present invention provides a method for removing metal residues at the edge of a wafer, and the method for removing metal residues at the edge of a wafer comprises the following steps:

[0035] S1: Attach a dicing film to the wafer as needed, specifically including the following steps:

[0036] A1: Before edge metal removal, the wafer to be processed must first be placed under a tool microscope, the radial width W of the remaining metal at the edge of the wafer measured, and the data recorded;

[0037] A2: Before cutting, the wafer needs to be coated with a scribing film. After the film is coated, the wafer 4a, the scribing film 4b, and the scribing ring 4c form a device that can be processed by the cutting equipment (such as Figure 4 shown);

[0038] S2: Load the wafer to be processed into the cutting machine. The processing platform rotates one circle with the center point of the wafer as the central axis to complete the cutting of the wafer edge. Before cutting, it is necessary to confirm whether there is any metal residue on the edge of the wafer to confirm the necessity of the removal operation. Since metal needs to be cut, the cutting blade used needs to be a special high-strength, wide-edge diamond blade. The specific steps include the following:

[0039] B1: Figure 3 The basic structure of the cutting equipment is shown. The processed device after filming is loaded onto the processing platform 3a of the equipment. The clamp 3b on the edge of the platform clamps the dicing ring 4c. At the same time, the platform vacuum absorbs and fixes the processed object. The cutting equipment is equipped with a micro camera unit 3c, through which the processing device can be positioned and the cutting effect can be observed (such as Figure 3 shown);

[0040] B2: Use the Edge Teach function of the device to find the edge of the processed wafer, and save the information in the device host at the same time. This operation can be used to locate the center of the wafer to ensure that the platform rotates around the center of the wafer during the cutting process. For the use of the Edge Teach function, please consult the equipment supplier;

[0041] B3: Enter the cutting depth, blade speed and other information into the program according to the operation requirements to ensure that the blade can stably cut through the wafer;

[0042] B4: Enter the metal residual radial width W data measured above into the program, that is, the length of the blade inward retraction when cutting (such as Figure 4 Wc in the figure) to ensure that the metal residue is completely removed. It should be noted that the cutting radius should not be close to the chip functional area 4d after shrinking, so as to avoid chip function failure during cutting;

[0043] B5: During cutting, the high-speed rotating blade 4e is set according to the above program, and descends to the set height in the chip invalid area inside the edge of the wafer, and the platform starts to rotate slowly with the wafer until a circle of cutting is completed;

[0044] B6: After the cutting is completed, the processed object is transferred to the cleaning table 3d, where it is cleaned and dried before being transferred out of the machine;

[0045] S3: Place the ring-cut wafer on the processing platform, manually tear off the dicing film that fixes the wafer, and automatically separate the cut waste from the wafer to complete the processing, which specifically includes the following steps:

[0046] C1: Place the cut product with its back facing up on a flat rubber platform. If necessary, add a dust-free cloth to prevent the front from being scratched.

[0047] C2: Peel off the dicing film along the edge and slowly separate the film from the wafer. When peeling off the film, try to keep the film and the wafer close to each other to reduce the vertical pulling force to avoid lifting the wafer. To prevent the wafer from shifting, press the peeled part of the wafer 5a with one hand when peeling off the film, and slowly pull back 5b with the other hand until the whole wafer is peeled off. Finally, separate the waste from the wafer;

[0048] If UV glue type scribing film is used, the wafer needs to be irradiated with UV light to debond before manual film tearing to ensure that the film tearing operation can be completed relatively easily;

[0049] After the above operations are completed, the processed wafer is placed under a microscope again to check the edge of the wafer to confirm the cutting effect and whether the metal residue has been removed.

[0050] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed by the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for removing metal residues from wafer edges, characterized in that: The method for removing metal residues at the edge of a wafer comprises the following steps: S1: Attach dicing film to the wafer as needed; S2: The wafer to be processed is loaded onto the cutting machine, and the processing platform rotates one circle around the center point of the wafer as the central axis to complete the cutting of a circle around the edge of the wafer; S3: Place the ring-cut wafer on the processing platform, manually tear off the dicing film that fixes the wafer, and automatically separate the cut waste from the wafer to complete the processing.

2. The method for removing metal residue from the edge of a wafer according to claim 1, characterized in that: In the step S2, whether there is any metal residue on the edge of the wafer before ring cutting is performed is confirmed to confirm the necessity of the removal operation.

3. The method for removing metal residue from wafer edge according to claim 2, characterized in that: In step S2, the cutting blade used by the cutting machine is a high-strength wide-edge diamond blade.

4. The method for removing metal residue from wafer edge according to claim 3, characterized in that: In the step S3, the wafer is debonded by ultraviolet light before the film is manually peeled off, thereby completing the film peeling operation.

5. The method for removing metal residue from wafer edge according to claim 4, characterized in that: The step S1 comprises the following specific steps: A1: Place the wafer to be processed under the tool microscope, measure the radial width W of the metal residue at the edge of the wafer, and record the data; A2: The wafer is filmed and the dicing film is attached to the wafer. After filming, the wafer, dicing film and dicing ring form a device that can be processed by the cutting equipment.

6. The method for removing metal residue at the edge of a wafer according to claim 5, characterized in that: The step S2 comprises the following specific steps: B1: Load the device that can be processed by the cutting equipment in step A2 onto the equipment processing platform, clamp the dicing ring with the clamp on the edge of the platform, and fix the processing object with vacuum adsorption on the platform. The cutting equipment has a micro camera unit, through which the processing device is positioned and the cutting effect is observed; B2: Use the Edge Teach function of the device to perform edge search on the processed wafer and save the information in the device host at the same time; B3: Enter the cutting depth and blade speed information into the program according to the job requirements; B4: Enter the metal residual radial width W data measured in step A1 into the program; B5: The high-speed rotating blade is set according to the above program. It descends to the set height in the chip invalid area inside the edge of the wafer. The platform starts to rotate slowly with the wafer until a circle of cutting is completed; B6: After cutting, the workpiece is sent to the cleaning table, where it is cleaned and dried before being sent out of the machine.

7. The method for removing metal residue at the edge of a wafer according to claim 6, characterized in that: The step S3 comprises the following specific steps: C1: Place the cut product with its back facing up on a flat rubber platform; C2: Peel off the dicing film along the edge, slowly separate the film from the wafer, and separate the waste from the wafer.

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