A method for dicing semiconductor chips

Abstract

The application discloses a kind of semiconductor chip dicing adhesion method, it can satisfy the stable adhesion demand of chip when dicing, chip can be prevented from edge collapse, chip can be prevented from pollution, the method comprises: the front surface of chip is coated with first photoresist, first photoresist is heated and solidified, the back surface of chip is coated with second photoresist, the back surface of chip is adhered to the upper surface of silicon substrate by second photoresist, vacuumizing treatment is carried out to chip and silicon substrate, chip and silicon substrate are heated and solidified, the lower surface of silicon substrate is adhered to polyester film, chip, silicon substrate and polyester film are diced, chip and silicon substrate are separated from polyester film, chip and silicon substrate are separated, chip is soaked, and residual first photoresist and second photoresist are removed.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically to an adhesive bonding method for dicing semiconductor chips. Background Technology

[0002] In semiconductor processing, dicing saws (i.e., dicing blades) or scribing and peeling techniques are commonly used to divide wafers into individual chips. For chips to be separated, they must first be adhered to a polyester film (such as a blue film or UV film) or a silicon substrate with a certain degree of elasticity, and then the wafer is divided according to a pre-set program using a high-speed rotating blade.

[0003] Currently, there are two common chip dicing processes: one involves directly dicing the chip after bonding it to a polyester film. This method is convenient and quick, and causes less chip contamination. However, this process has high requirements for the thickness and viscosity of the polyester film. For thin polyester films with low viscosity (approximately 80 μm thick), the dicing stability is poor, and the resulting chip is prone to edge chipping. Figure 1 In the diagram, area A represents the chipping area, where cracks or chipping occur on the back or sides of the chip. While thicker, high-viscosity polyester films (approximately 160 μm thick) can improve dicing stability, they cannot be expanded on a film expander, and manual removal of the wafer easily results in scratches, bumps, and other defects caused by human error. Therefore, to achieve optimal dicing results, the polyester film needs to be customized, but this drastically increases costs. Another approach uses a silicon wafer substrate, employing paraffin wax to bond the chip to the substrate. During dicing, the silicon substrate can hold the chip in place, preventing chipping. However, paraffin wax is stable and difficult to dissolve and remove, leading not only to chip contamination but also severely impacting subsequent processing steps. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, the present invention provides a bonding method for dicing semiconductor chips, which can meet the requirements for stable bonding of chips during dicing, while preventing chip edge breakage and chip contamination.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A bonding method for dicing semiconductor chips, characterized in that the method includes: S1, coating a first photoresist on the front side of the chip;

[0007] S2. Heat and cure the first photoresist;

[0008] S3. Coat the back of the chip with a second photoresist, and bond the back of the chip to the upper surface of the silicon substrate using the second photoresist;

[0009] S4. Vacuum treatment is performed on the chip and the silicon substrate after steps S2 and S3.

[0010] S5. The chip and the silicon substrate processed in step S4 are heated and cured.

[0011] S6. Adhere the lower surface of the silicon substrate to the polyester film;

[0012] S7. The chip, silicon substrate and polyester film processed in step S6 are diced.

[0013] S8. Separate the chip and the silicon substrate from the polyester film;

[0014] S9. Separate the chip from the silicon substrate;

[0015] S10. Immerse the chip after step S9 to remove residual first and second photoresist.

[0016] Its further feature is that,

[0017] In step S1, the first photoresist is uniformly coated on the front side of the chip using a spin coater;

[0018] The first photoresist is of type AZ1505, and the coating thickness of the first photoresist is 0.5μm to 4μm;

[0019] In step S2, the chip coated with the first photoresist is placed on a heating stage for heating to cure the first photoresist. The heating time is 3 to 10 minutes and the heating temperature is 80°C to 120°C.

[0020] In step S3, the second photoresist is uniformly coated on the back of the chip using a spin coater;

[0021] The second photoresist is model AZ10XT, and the coating thickness of the second photoresist is 4μm to 10μm. This thickness limit ensures the strong adhesion between the chip and the silicon substrate.

[0022] In step S4, a vacuum oven is used to perform a vacuum treatment on the bonded chip and the silicon substrate. The baking temperature of the vacuum oven is 5℃~20℃, and the vacuum treatment lasts for 5 minutes~20 minutes, which ensures the tightness of the bond between the chip and the silicon substrate.

[0023] The vacuum oven is model DZF-6020;

[0024] In step S5, the chip after vacuum treatment and the silicon substrate are placed on a heating stage for heating to cure the second photoresist. The heating duration is 5 to 15 minutes and the heating temperature is 80°C to 120°C.

[0025] In step S6, the polyester film is a UV film or a blue film;

[0026] In step S7, a dicing machine is used for dicing, and the model of the dicing machine is NANO320-NDS;

[0027] In step S8, a debonding machine is used to debond the chip, silicon substrate and polyester film after step S7, so that the silicon substrate is separated from the polyester film.

[0028] In step S9, acetone is sprayed onto the bonding area between the chip and the silicon substrate using a pressure spray gun to separate the chip from the silicon substrate.

[0029] In step S10, the chip is immersed in an acetone solution for 5 to 20 hours.

[0030] The method described above by this invention achieves the following beneficial effects: In this application, a second photoresist is used to bond the chip to the silicon substrate. Compared to directly bonding the UV film, the silicon substrate provides support and fixation for the chip, effectively increasing the stability during chip dicing and significantly reducing edge chipping. Furthermore, a polyester film can be used to bond the chip to the silicon substrate before dicing, eliminating the need for a custom-made UV film with a suitable thickness, thus reducing investment costs.

[0031] In addition, the first and second photoresists are easily dissolved and removed by acetone solution. Compared with the method of using paraffin to bond the chip to the silicon substrate, the use of the second photoresist effectively prevents the problem of chip contamination caused by the residue of the adhesive on the chip surface. It is beneficial to improve the cleaning effect after the chip is diced, and at the same time, it is beneficial to the rapid separation and cleaning of the chip and the silicon substrate, thus improving production efficiency.

[0032] In summary, the method described in this application not only improves the cleaning effect and processing efficiency, but also effectively increases the stability of chip dicing and significantly reduces edge chipping. Attached Figure Description

[0033] Figure 1 This is a chip rendering showing edge chipping during wafer (chip) dicing using existing processes;

[0034] Figure 2 This is a flowchart of the method of the present invention;

[0035] Figure 3 This is a schematic diagram of the main structure after the chip, silicon substrate, and polyester film are bonded using the method of the present invention;

[0036] Figure 4 This is a diagram of the chip after dicing using the method of this invention;

[0037] Figure 5 This is a top view of the structure of the chip, silicon substrate and polyester film after bonding. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and the above-mentioned drawings of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, apparatus, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to these processes, methods, products or devices.

[0039] The existing technology of directly bonding and dicing the chip to the polyester film 5 is prone to edge chipping. (See...) Figure 1 To reduce edge chipping, the thickness of the polyester film 5 needs to be customized according to the dicing stability. Customizing the polyester film 5 increases the investment cost. Although using wax to bond the chip to the silicon substrate can reduce edge chipping, the wax is not easy to dissolve and remove, causing chip contamination. This invention provides several specific embodiments of bonding methods for semiconductor chip dicing.

[0040] See Figure 2 Example 1: The method includes: S1, uniformly coating the front side of the chip 1 with a first photoresist 2 using a spin coater. The first photoresist 2 is of type AZ1505 and the coating thickness of the first photoresist 2 is 0.5μm.

[0041] S2. Place the chip 1 coated with the first photoresist 2 on a heating stage and heat it to cure the first photoresist 2. The heating time is 3 minutes and the heating temperature is 90°C.

[0042] S3. Use a spin coater to uniformly coat the back of chip 1 with second photoresist 3, and use the second photoresist 3 to bond the back of chip 1 to the upper surface of silicon substrate 4; the second photoresist 3 is of type AZ10XT and the coating thickness of the second photoresist 3 is 4μm.

[0043] S4. A vacuum oven is used to perform vacuum treatment on the chip 1 and silicon substrate 4 after steps S2 and S3. The baking temperature of the vacuum oven is 5°C and the vacuum treatment lasts for 5 minutes. The model of the vacuum oven is DZF-6020.

[0044] S5. Place the vacuum-treated chip 1 and silicon substrate 4 on a heating stage for heating to cure the second photoresist 3. The heating duration is 5 minutes and the heating temperature is 80°C.

[0045] S6. The lower surface of the silicon substrate 4 is bonded to the polyester film 5. In this embodiment, the polyester film 5 is a blue film. The cost of the blue film is lower than that of the UV film, which helps to save costs. See Figure 3 , Figure 5 ;

[0046] S7. The chip 1, silicon substrate 4 and polyester film 5 processed in step S6 are diced using a dicing machine. The model of the dicing machine is NANO320-NDS.

[0047] S8. Use a debonding machine to debond the chip 1, silicon substrate 4 and polyester film 5 after step S7, so that the silicon substrate 4 is separated from the polyester film.

[0048] S9. Use a pressure spray gun to spray acetone at the bonding point between chip 1 and silicon substrate 4 to separate chip 1 from silicon substrate 4.

[0049] S10. The separated chip 1 is immersed in acetone solution for 5h to 20h to remove residual first and second photoresist; the purity of the acetone solution is 99.99%.

[0050] Example 2, the method includes: S1, uniformly coating the front side of chip 1 with a first photoresist using a spin coater, the first photoresist being AZ1505 and having a coating thickness of 2μm;

[0051] S2. Place the chip 1 coated with the first photoresist on a heating stage and heat it to cure the first photoresist 1. The heating time is 6 minutes and the heating temperature is 100℃.

[0052] S3. Use a spin coater to uniformly coat the back of chip 1 with second photoresist 3, and use the second photoresist 3 to bond the back of chip 1 to the upper surface of silicon substrate 4; the second photoresist 3 is of type AZ10XT and the coating thickness of the second photoresist 3 is 7μm.

[0053] S4. The chip and silicon substrate 4 after steps S2 and S3 are subjected to vacuum treatment using a vacuum oven. The baking temperature of the vacuum oven is 12℃ and the vacuum treatment lasts for 12 minutes. The model of the vacuum oven is DZF-6020.

[0054] S5. Place the vacuum-treated chip 1 and silicon substrate 4 on a heating stage for heating to cure the second photoresist. The heating duration is 12 minutes and the heating temperature is 100℃.

[0055] S6. The lower surface of the silicon substrate 4 is bonded to the polyester film. In this embodiment, the polyester film 5 is a blue film, which has a lower cost compared to the UV film.

[0056] S7. The chip 1, silicon substrate 4 and polyester film 5 processed in step S6 are diced using a dicing machine. The model of the dicing machine is NANO320-NDS.

[0057] S8. Use a debonding machine to debond the chip 1, silicon substrate 4 and polyester film 5 after step S7, so that the silicon substrate 4 and polyester film 5 are separated.

[0058] S9. Use a pressure spray gun to spray acetone at the bonding point between chip 1 and silicon substrate 4 to separate chip 1 from silicon substrate 4.

[0059] S10. The separated chip 1 is immersed in acetone solution for 12 hours to remove residual first and second photoresist; the mass concentration of acetone in the acetone solution is 99.99%.

[0060] Example 3, the method includes: S1, uniformly coating the front side of the chip 1 with a first photoresist 2 using a spin coater, the first photoresist 2 being of type AZ1505 and having a coating thickness of 4μm;

[0061] S2. The chip 1 coated with the first photoresist 2 is placed on a heating stage and heated to cure the first photoresist 2. The heating time is 10 minutes and the heating temperature is 100℃. The first photoresist is coated on the front side of the chip. The first photoresist covers the entire surface area of ​​the front side of the chip, which plays a protective role and avoids the chip surface from being damaged by the debris generated during the dicing process under the action of high-speed rotation force.

[0062] S3. Use a spin coater to uniformly coat the back of chip 1 with second photoresist 3, and use the second photoresist 3 to bond the back of chip 1 to the upper surface of silicon substrate 4; the second photoresist 3 is of type AZ10XT and the coating thickness of the second photoresist 3 is 10μm.

[0063] S4. A vacuum oven is used to perform vacuum treatment on the chip 1 and silicon substrate 4 after steps S2 and S3. The baking temperature of the vacuum oven is 20°C and the vacuum treatment lasts for 20 minutes. The model of the vacuum oven is DZF-6020.

[0064] S5. Place the vacuum-treated chip 1 and silicon substrate 4 on a heating stage for heating to cure the second photoresist 3. The heating duration is 15 minutes and the heating temperature is 120°C.

[0065] S6. The lower surface of the silicon substrate 4 is bonded to the polyester film. In this embodiment, the polyester film 5 is a blue film. The cost of the blue film is lower than that of the UV film, which helps to further save costs. The area of ​​the blue film is larger than the area of ​​the lower surface of the silicon substrate. When the silicon substrate is attached to the blue film, the four edges of the blue film protrude beyond the four edges of the silicon substrate. Figure 3 , Figure 5 The silicon substrate is positioned in the center of the blue film. This attachment method increases the contact area between the workpiece (i.e., the bonded silicon substrate and blue film) and the worktable. Increased contact area improves stability during the dicing process, thereby enhancing the dicing effect and preventing edge chipping. In this field, to avoid wear on the silicon substrate or chip surface, a vacuum adsorption device is often used to clamp the workpiece during dicing. Before using the vacuum adsorption method on the dicing worktable, the blue film is attached to the lower surface of the silicon substrate using the above method. The use of the blue film not only further saves costs and prevents wear on the silicon substrate surface (facilitating reuse), but also increases the contact area between the workpiece and the worktable, improving adsorption firmness. Furthermore, the blue film is flatter and has better sealing properties than the bottom surface of the silicon substrate, making it more conducive to firm adsorption by the worktable. Therefore, attaching the blue film to the bottom surface of the silicon substrate further improves stability during the dicing process, preventing chip edge chipping or damage to the silicon substrate.

[0066] S7. The chip, silicon substrate and polyester film 5 processed in step S6 are diced using a dicing machine, the model of which is NANO320-NDS.

[0067] S8. Use a debonding machine to debond the chip, silicon substrate and polyester film after step S7, so that the silicon substrate and polyester film 5 are separated.

[0068] S9. Use a pressure spray gun to spray acetone at the bonding area between the chip and the silicon substrate to separate the chip from the silicon substrate. When using a pressure spray gun to spray the acetone solution, spray along the perimeter of the chip and silicon substrate (the perimeter is the bonding area between the chip and the silicon substrate). This not only helps to save acetone solution and further reduce costs, but also facilitates the rapid immersion of the acetone solution into the second photoresist used to bond the chip and the silicon substrate, allowing for rapid separation of the chip and the silicon substrate and further improving processing efficiency.

[0069] S10. The separated chip is immersed in acetone solution for 20 hours to effectively remove residual first and second photoresist; the mass concentration of acetone solution is 99.99%.

[0070] In Examples 1 to 3 above, the viscosity of the first photoresist is 10 cP to 100 cP, and the viscosity of the second photoresist is 220 cP. The viscosity of the first photoresist is less than or equal to that of the second photoresist, and the thickness of the first photoresist is less than that of the second photoresist. This is because the first photoresist only serves a surface protection function and does not require strong adhesion; therefore, a higher viscosity and greater thickness are sufficient for protection. This also facilitates rapid curing and cleaning in subsequent processes, further improving processing efficiency. The higher viscosity and greater thickness of the second photoresist, however, promotes a stable bond between the chip and the silicon substrate, further ensuring the stability of the dicing process and preventing edge chipping. Furthermore, in Examples 1 to 3, a vacuum oven is used to bake the chip, allowing air bubbles to escape from the bonding surface between the chip and the silicon substrate. This prevents weak bonding due to air bubbles, further ensuring a stable bond between the chip and the silicon substrate and further preventing edge chipping. The conventional photoresist curing method is ultraviolet light curing. Ultraviolet light curing cures the photoresist immediately after it is applied, which cannot guarantee that air bubbles will be completely removed. However, the vacuum oven baking method used in this application ensures that air bubbles in the second photoresist at the bonding area between the chip and the silicon substrate are effectively removed.

[0071] In summary, the advantages of using the bonding method of this application are as follows:

[0072] (1) In this application, the chip is an infrared detector chip, but is not limited to an infrared detector chip. The method of this application is applied to the processing of infrared detector chips. Figure 4 This is a schematic diagram of the chip structure after dicing using the method of the present invention. Figure 4 As can be seen, there is no chipping on the side of the chip after dicing. Therefore, the method of this application can effectively reduce chipping during chip dicing and ensure the quality of the finished product.

[0073] (2) Cleaning is very important in the chip manufacturing process. The use of the first photoresist and the second photoresist in this application ensures uniformity, that is, effective cleaning can be achieved by using the same solution, avoiding the possibility of other contamination caused by using different solutions for cleaning.

[0074] (3) In this application, the thickness of the first photoresist and the second photoresist is limited. If the thickness of the first photoresist is too thin, the front side of the chip is easily damaged. If it is too thick, it will form a large hardness difference with the workpiece, causing instability in the dicing process. If the second photoresist is too thin, the bonding effect will be poor. If it is too thick, it will also cause dicing instability. Therefore, the limitation of the thickness of the first photoresist and the second photoresist in this application further reduces the edge chipping phenomenon and ensures the quality of the finished product.

[0075] (4) In practical applications, both the first photoresist and the second photoresist can be cured at room temperature or heated by existing heating devices (or heating tables) to dry. The difference between the two is the time. The heating method of the heating table used in this application can effectively reduce the curing time and further improve the processing efficiency.

[0076] (5) The method of this application not only improves the cleaning effect and processing efficiency, but also effectively increases the stability of chip dicing and greatly reduces edge breakage.

[0077] The above are merely preferred embodiments of this application, and the present invention is not limited to the above embodiments. It is understood that other improvements and variations that are directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included within the protection scope of the present invention.

Claims

1. A method of dicing a semiconductor chip, characterized by, The method comprises the following steps: S1, applying a first photoresist on the front surface of a chip; S2, heating and curing the first photoresist; S3, applying a second photoresist on the back surface of the chip, and bonding the back surface of the chip to the upper surface of a silicon substrate through the second photoresist; S4, performing vacuumizing treatment on the chip and the silicon substrate after the steps S2 and S3; S5, heating and curing the second photoresist by heating the chip and the silicon substrate after the step S4; S6, bonding the lower surface of the silicon substrate to a polyester film; the polyester film is a UV film or a blue film, and the area of the UV film or the blue film is larger than the area of the lower surface of the silicon substrate; when the silicon substrate is attached to the UV film or the blue film, the four edges of the UV film or the blue film protrude from the four edges of the silicon substrate; S7, scribing the chip, the silicon substrate and the polyester film after the step S6; S8, separating the chip, the silicon substrate and the polyester film after scribing; S9, separating the chip and the silicon substrate; S10, immersing the chip after the step S9 to remove the residual first photoresist and second photoresist.

2. The semiconductor die dicing method according to claim 1, wherein In the step S1, the first photoresist is uniformly applied on the front surface of the chip by using a glue spinner; the thickness of the first photoresist is 0.5-4 μm.

3. The semiconductor die dicing method according to claim 2, wherein In the step S2, the chip after applying the first photoresist is heated by a heating table to cure the first photoresist; the heating time is 3-10 minutes, and the heating temperature is 80-120℃.

4. The semiconductor die dicing method according to claim 3, wherein In the step S3, the second photoresist is uniformly applied on the back surface of the chip by using a glue spinner; the thickness of the second photoresist is 4-10 μm.

5. The semiconductor die dicing method according to claim 4, wherein In the step S4, the vacuumizing treatment is performed on the bonded chip and silicon substrate by using a vacuum oven; the baking temperature of the vacuum oven is 5-20℃, and the vacuumizing duration is 5-20 minutes.

6. The semiconductor die dicing method according to claim 5, wherein In the step S5, the chip and the silicon substrate after the vacuumizing treatment are heated by a heating table to cure the second photoresist; the heating duration is 5-15 minutes, and the heating temperature is 80-120℃.

7. The semiconductor die dicing method according to claim 6, wherein In the step S8, the chip, the silicon substrate and the polyester film after the step S7 are separated by using a glue stripper.

8. The semiconductor die dicing method according to claim 7, wherein In the step S9, the chip and the silicon substrate are separated by spraying acetone on the bonding position of the chip and the silicon substrate by using a pressure spray pen.

9. The semiconductor die dicing method according to claim 8, wherein In the step S10, the chip is immersed in an acetone solution for 5-20 hours.

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