Wafer thickness reduction abnormality processing method

Abstract

The application discloses a wafer thickness thinning abnormality processing method, comprising the following steps: pasting a front adhesive film on a wafer with a thickness of less than 400 microns after grinding, and then performing thinning processing and grinding processing. The wafer thickness thinning abnormality processing method provided by the application selects a front adhesive film with strong viscosity and appropriate thickness, ensures firm combination of the front adhesive film and the wafer, improves product strength, avoids wafer cracking risk, selects different grinding modes according to different grinding amounts, finally performs manual grinding processing, ensures product quality, can solve wafer thickness thinning abnormality or temporary thickness change problems, and is simple in process and suitable for industrial popularization and use.

Description

Technical Field

[0001] This invention belongs to the field of packaging technology, and specifically relates to a method for handling wafer thickness reduction anomalies. Background Technology

[0002] Before packaging, wafers are typically 775 μm thick. Backside grinding can reduce this thickness, thus decreasing the packaged product's size. However, in actual manufacturing, situations may arise where the ground thickness does not meet requirements or temporary thickness changes necessitate rework. Therefore, developing a method for handling wafer thickness reduction anomalies is essential. Summary of the Invention

[0003] To address the technical problems existing in the prior art, the present invention aims to provide a method for handling wafer thickness reduction anomalies.

[0004] To achieve the above objectives and technical effects, the technical solution adopted by this invention is as follows:

[0005] A method for handling wafer thickness reduction anomalies includes the following steps: applying a front-side adhesive film to a wafer with a thickness of less than 400 μm after grinding, followed by thinning and grinding.

[0006] Furthermore, the step of applying a front-side adhesive film to wafers with a thickness of less than 400μm after grinding includes:

[0007] First, modify the wafer thickness parameter to the lowest value and select a dummy wafer of the same thickness;

[0008] When the fake film is placed on the film application table of the equipment, disconnect the safety door sensor to prevent the equipment from closing the alarm safety door and put the equipment in a paused state.

[0009] Remove the dummy wafer from the film application table, then place the wafer to be reworked on the film application table and continue running the equipment to complete the application of the front adhesive film.

[0010] After the film is applied, disconnect the safety door sensor again to pause the device alarm. Use a blade to cut the front adhesive film along the edge of the film application table. Carefully remove the wafer with the front adhesive film applied. Use the blade to trim any excess front adhesive film on the wafer edge.

[0011] Furthermore, the front adhesive film is model HT-440HBA-PE2, with a thickness of 440μm and an adhesive strength of 0.25N / 25mm after ultraviolet irradiation.

[0012] Further, the thinning process includes:

[0013] Determine the appropriate thinning process based on the grinding amount:

[0014] If the grinding depth is ≤50μm, use Z2→Z3 grinding wheels for grinding;

[0015] If the grinding depth is greater than 50μm, use grinding wheels Z1→Z2→Z3 for grinding.

[0016] Furthermore, if the grinding amount is ≤50μm, the Z2 grinding wheel is selected as a diamond grinding wheel with a mesh size of 6000 or higher, and the Z3 grinding wheel is a DP-F05 dry polishing grinding wheel.

[0017] Furthermore, if the grinding amount is ≤50μm, the feed rate of the Z2 grinding wheel is 0.2-0.4μm / s, and the feed rate of the Z3 grinding wheel is 1-2μm / s.

[0018] Furthermore, if the grinding amount is >50μm, the Z1 grinding wheel is a diamond grinding wheel with a diamond mesh size of 320, the Z2 grinding wheel is a diamond grinding wheel with a diamond mesh size of 6000 or higher, and the Z3 grinding wheel is a DP-F05 dry polishing grinding wheel.

[0019] Furthermore, if the grinding amount is >50μm, the feed rate of the Z1 grinding wheel is 1-4μm / s, the feed rate of the Z2 grinding wheel is 0.2-0.4μm / s, and the feed rate of the Z3 grinding wheel is 1-2μm / s.

[0020] Further, the grinding process includes:

[0021] First, determine the thickness of the product to be ground, and then select the appropriate grinding process mode or polishing mode.

[0022] Place the product to be ground on the chuck table and grind it according to the selected mode;

[0023] After grinding, the product is cleaned and inspected to confirm its quality.

[0024] Furthermore, the grinding process mode is Z1→Z2 grinding wheels for grinding, and the polishing mode is Z1→Z2→Z3.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention discloses a method for handling wafer thickness reduction anomalies, comprising the following steps: applying a front-side adhesive film to a wafer with a thickness of less than 400 μm after grinding, followed by thinning and grinding. The method provided by this invention first selects a front-side adhesive film with strong adhesion and appropriate thickness to ensure a firm bond between the film and the wafer while improving product strength and avoiding the risk of wafer breakage. Then, different grinding modes are selected according to different grinding amounts. Finally, manual grinding is performed to ensure product quality. This method can solve the problem of wafer thickness reduction anomalies or temporary thickness changes. The process is simple and suitable for industrial-scale application. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of applying the adhesive film to the front side of the device according to the present invention;

[0028] Figure 2 This is a schematic diagram of the present invention when using a blade to cut the front adhesive film;

[0029] Figure 3 This is a schematic diagram showing the film application process after the present invention is completed. Detailed Implementation

[0030] The present invention will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0031] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0032] like Figure 1-3 As shown, a method for handling abnormal wafer thickness reduction includes the following steps: First, a dummy wafer 1 is placed in the film-applying worktable 2 of the equipment for automatic operation, then replaced with the wafer 3 to be reworked, and the front-side adhesive film 4 is applied. After completion, thinning and manual grinding are performed. Specifically, the method includes the following steps:

[0033] 1) Selection of Front Adhesive Film: Since the wafer has already undergone one grinding process, its warpage is greater than before grinding, and its strength is lower. There is a risk of wafer breakage during the second application of the front adhesive film 4 and grinding process. To mitigate this risk, the front adhesive film 4 needs to be a film with strong adhesion and a thick adhesive layer. The strong adhesion of the front adhesive film 4 ensures a stronger bond between the wafer's front side (bump side) and the adhesive film, reducing the risk of water ingress and wafer cracking during grinding. The thick adhesive film increases the overall thickness of the product after application, increasing product strength and reducing the likelihood of breakage. The front adhesive film 4 of this invention preferably uses an adhesive film with an adhesion strength of 5.5 N / 25 mm before UV irradiation, an adhesion strength of 0.25 N / 25 mm after UV irradiation, and a thickness of 440 μm, model HT-440HBA-PE2.

[0034] 2) Film application: The mainstream equipment used in the industry for applying the front-side adhesive film 4 is the DR300 IV, which cannot auto-process wafers with a thickness of less than 400μm. Therefore, the following steps are used to apply the film to wafers 3 that need to be reworked and have a thickness of less than 400μm:

[0035] 21) Before the equipment automatically loads the product, it performs a mapping scan on the product status. When the product thickness is less than 400μm, it exceeds the equipment limit. During mapping, an alarm is triggered indicating abnormal product thickness, and the AUTO operation cannot be performed. Therefore, the wafer thickness parameter is first modified to 400μm, and a dummy wafer 1 with a thickness of 400μm is used for automatic operation.

[0036] 22) When the fake film 1 is placed on the film application workbench 2 of the equipment, disconnect the safety door sensor to cause the equipment to alarm that the safety door is not closed, thus putting the equipment in a paused state.

[0037] 23) Remove the dummy wafer 1 from the film application table 2, then place the wafer 3 to be reworked on the film application table 2 and continue running the equipment to complete the front adhesive film application process. Figure 1 );

[0038] 24) After the film application is completed, disconnect the safety door sensor again to pause the equipment alarm. Because the wafer 3 to be reworked was manually placed on the film application table 2, its position on the table 2 cannot match the position automatically placed by the equipment. There is a positional deviation. If the equipment is allowed to automatically cut the front adhesive film 4 at this time, there is a risk of cutting the wafer edge and causing wafer cracking. Therefore, use a blade to manually cut the front adhesive film 4 along the edge of the film application table 2. Figure 2 Then release the vacuum on the film application table, carefully remove the wafer with the front adhesive film 4 applied, and use a blade to trim any excess front adhesive film 4 at the wafer edges. Figure 3 ).

[0039] 3) Thinning: Determine the appropriate thinning process based on the grinding amount;

[0040] If the grinding amount is ≤50μm, use Z2→Z3 grinding wheels for grinding. For Z2 grinding wheels, select grinding wheels with a diamond mesh of 6000 or higher. For Z3 grinding wheels, DP-F05 dry polishing grinding wheels are recommended. See Table 1 for process parameters.

[0041] If the grinding depth is greater than 50μm, use Z1→Z2→Z3 grinding wheels for grinding. Select a diamond grinding wheel with a diamond mesh size of 320 for Z1, a diamond grinding wheel with a diamond mesh size of 6000 or higher for Z2, and a DP-F05 dry polishing grinding wheel for Z3. See Table 1 for process parameters.

[0042] Table 1

[0043]

[0044] 4) Manual grinding:

[0045] 41) Confirm the product thickness, select the corresponding program, and then select the grinding process mode Z1→Z2 (for polishing, select Z1→Z2→Z3);

[0046] 42) Place the product to be ground in a chuck table to create a vacuum.

[0047] 43) After grinding is complete, the product is transferred to the cleaning tray in the fully automated DFM2800 process.

[0048] 44) After the fully automatic process ends, perform normal inspections on the products to confirm their quality.

[0049] Any parts or structures not specifically described in this invention can be made using existing technologies or products, and will not be elaborated upon here.

[0050] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for processing wafer thickness reduction abnormality, characterized by, The method comprises the following steps: The wafer with a thickness of less than 400 microns is pasted with a front adhesive film, and then subjected to a thinning treatment and a grinding treatment; The step of pasting the wafer with a thickness of less than 400 microns with a front adhesive film comprises: First, modify the wafer thickness parameter to the minimum value, and select a dummy wafer with the same thickness; When the dummy wafer is placed on the film pasting workbench of the device, pull out the safety door sensor to make the device alarm the safety door not to close, so that the device is in a suspended state; Take out the dummy wafer on the film pasting workbench, and then place the wafer to be reworked on the film pasting workbench to continue running the device to complete the pasting of the front adhesive film; After the film pasting is completed, pull out the safety door sensor again to make the device alarm in a suspended state, cut the front adhesive film along the edge of the film pasting workbench using a blade, and carefully take out the wafer with the pasted front adhesive film, and trim the excess front adhesive film on the edge of the wafer using a blade; The model of the front adhesive film is HT-440HBA-PE2, the thickness is 440 microns, and the adhesive strength after ultraviolet irradiation is 0.25 N / 25 mm; The step of the thinning treatment comprises: According to the grinding amount, determine the appropriate thinning process: If the grinding amount is less than or equal to 50 microns, use Z2→Z3 grinding wheels for grinding; If the grinding amount is greater than 50 microns, use Z1→Z2→Z3 grinding wheels for grinding; If the grinding amount is less than or equal to 50 microns, the Z2 grinding wheel selects a grinding wheel with a diamond mesh of 6000 meshes or more, and the Z3 grinding wheel is a DP-F05 dry polishing grinding wheel; If the grinding amount is less than or equal to 50 microns, the feeding rate of the Z2 grinding wheel is 0.2-0.4 microns / s, and the feeding rate of the Z3 grinding wheel is 1-2 microns / s; If the grinding amount is greater than 50 microns, the Z1 grinding wheel adopts a grinding wheel with a diamond mesh of 320 meshes, the Z2 grinding wheel adopts a grinding wheel with a diamond mesh of 6000 meshes or more, and the Z3 grinding wheel adopts a DP-F05 dry polishing grinding wheel; If the grinding amount is greater than 50 microns, the feeding rate of the Z1 grinding wheel is 1-4 microns / s, the feeding rate of the Z2 grinding wheel is 0.2-0.4 microns / s, and the feeding rate of the Z3 grinding wheel is 1-2 microns / s; The step of the grinding treatment comprises: First, confirm the thickness of the product to be ground, and select a suitable grinding process mode or polishing mode; Place the product to be ground on the chuck workbench, and grind according to the selected mode; After grinding, clean and inspect the product to confirm the product quality; The grinding process mode is Z1→Z2 grinding wheel grinding, and the polishing mode is Z1→Z2→Z3.

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