Cutting method for composite structure of ultrathin silicon wafer and carrier
By combining grinding wheel cutting and laser cutting processes in chip production, the ultra-thin silicon wafer and carrier composite structure is cut, solving the problem of stress-induced damage during ultra-thin silicon wafer cutting, achieving an efficient and low-cost cutting effect.
Patent Information
- Application Number
- CN202510002105.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-02
- Publication Date
- 2025-04-22
AI Technical Summary
During the chip production process, ultra-thin silicon wafers are damaged due to poor support performance and stress during cutting, and the prior art lacks convenient cutting methods.
The front of the composite structure is cut by grinding wheel cutting process to form scratches, and the back of the composite structure is cut under the laser cutting process to form multiple chip particles.
By combining grinding wheel cutting and laser cutting processes, efficient cutting of ultra-thin silicon wafer and carrier composite structure is achieved, reducing costs and improving cutting efficiency, while avoiding cutting stress problems in the prior art.
Smart Images
Figure CN119858241A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of semiconductor chips, and in particular relates to a cutting method for a composite structure of an ultra-thin silicon wafer and a carrier. Background Art
[0002] As the requirements for the electrical performance of chips are getting higher and higher, the thickness of chips is getting thinner and thinner. However, in the production process of chips, when cutting ultra-thin silicon wafers, the wafers are too thin and have poor support performance. When they are cut directly, the stress of cutting will cause the wafer to be damaged. Therefore, the ultra-thin silicon wafers are temporarily bonded to the carrier using temporary bonding glue to form a composite structure to increase the support for the ultra-thin silicon wafers, and then cut. However, there is no method in the prior art that is convenient for cutting the above composite structure. Summary of the invention
[0003] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a cutting method for a composite structure of an ultra-thin silicon wafer and a carrier.
[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:
[0005] A method for cutting a composite structure of an ultra-thin silicon wafer and a carrier, wherein the composite structure is formed by temporarily bonding the ultra-thin silicon wafer to the carrier through a temporary bonding adhesive, thereby forming a bonding adhesive layer between the ultra-thin silicon wafer and the carrier; the surface of the ultra-thin silicon wafer of the composite structure is its front side, and the surface of the carrier of the composite structure is its back side; the cutting method comprises the following steps:
[0006] The front side of the composite structure is cut by a grinding wheel cutting process, and the ultra-thin silicon wafer and the bonding adhesive layer are completely cut through at the cutting point to form scratches;
[0007] The back side of the composite structure is cut at the position of the scratch by using a laser cutting process, and the carrier at the scratch is cut through to form a plurality of chip particles.
[0008] Furthermore, the thickness of the ultra-thin silicon wafer is 5 μm to 50 μm; the thickness of the bonding adhesive layer is 30 μm to 50 μm.
[0009] Furthermore, the carrier is a glass carrier; the thickness of the glass carrier is 300 μm to 600 μm.
[0010] Furthermore, before cutting the front side of the composite structure using a grinding wheel cutting process, a first processing carrier film is first pasted on the back side of the composite structure, and after the front side of the composite structure is cut, the first processing carrier film is removed from the back side of the composite structure.
[0011] Furthermore, before using the laser cutting process to cut the back side of the composite structure, a second processing carrier film is first pasted on the front side of the composite structure. After the back side of the composite structure is cut, the chip particles formed after cutting the composite structure are removed from the second processing carrier film.
[0012] Furthermore, the grinding wheel cutting process is a hard knife cutting process.
[0013] Furthermore, the cutting blade used in the hard knife cutting process is an ultra-thin hard knife cutting blade, and the thickness of the ultra-thin hard knife cutting blade is 20 μm to 30 μm.
[0014] Furthermore, when the front side of the composite structure is cut by a grinding wheel cutting process, the rotation speed of the cutting blade is 25000 r / min to 30000 r / min, and the feed rate is 5 to 10 mm / s.
[0015] Furthermore, the laser cutting process used when cutting the back side of the composite structure is a laser hidden cutting process.
[0016] Furthermore, when the back side of the composite structure is cut by a laser hidden cutting process, the line width of the laser is 1 μm to 2 μm, and the step distance is 5 μm to 15 μm.
[0017] In the present invention, the two sides of the composite structure are cut by using a hard knife cutting process and a laser hidden cutting process, respectively, thereby combining the advantages of the above two traditional processes and avoiding the adverse effects of their disadvantages on the composite structure of the ultra-thin silicon wafer and the carrier, having high feasibility and fault tolerance, facilitating the cutting operation of the composite structure, and having low cutting cost and high efficiency. In addition, the use of a transparent glass carrier can also facilitate alignment with the scratches on the front when cutting the back side, thereby improving the cutting accuracy. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:
[0019] Figure 1 The figure is a flow chart of an embodiment of a method for cutting a composite structure of an ultra-thin silicon wafer and a carrier according to the present invention.
[0020] Figure 2 A schematic diagram of the composite structure.
[0021] Figure 3 Schematic diagram of cutting the front side of the composite structure.
[0022] Figure 4 Schematic diagram of cutting the front and back sides of the composite structure.
[0023] Figure 5 Schematic diagram of cutting to form chip particles.
[0024] The accompanying drawings in the specification are numeraled as follows:
[0025] Ultra-thin silicon wafer-100; bonding adhesive layer-200; carrier-300; first processing carrier film-400; second processing carrier film-500; cutting blade-600; scratch-700; laser-800; chip particles-900. DETAILED DESCRIPTION
[0026] The following describes the implementation methods of the present invention through specific examples. The illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention. The following embodiments and features in the embodiments may be combined with each other without conflict.
[0027] See also Figure 1 , Figure 1 This is a flow chart of an embodiment of a method for cutting a composite structure of an ultra-thin silicon wafer and a carrier according to the present invention. Figure 2 The composite structure is formed by temporarily bonding the ultra-thin silicon wafer 100 to the carrier 300 through a temporary bonding adhesive, thereby forming a bonding adhesive layer 200 between the ultra-thin silicon wafer 100 and the carrier 300.
[0028] The surface of the composite structure ultra-thin silicon wafer 100 is its front side, and the surface of the composite structure carrier 300 is its back side. The thickness of the ultra-thin silicon wafer 100 is generally 5 μm to 50 μm; for example, the thickness of the bonding adhesive layer 200 is generally 30 μm to 50 μm. In this embodiment, in order to facilitate alignment with the scratch 700 on the front side during back cutting, the carrier 300 uses a transparent glass carrier (quartz glass is used as the glass carrier in this embodiment); the thickness of the glass carrier is generally 300 μm to 600 μm.
[0029] There are two main methods for wafer cutting, one is the grinding wheel cutting method, and the other is the laser cutting method. Among them, the grinding wheel cutting method is divided into hard knife cutting process (processing semiconductor brittle materials) and soft knife cutting process (processing hard materials such as glass and ceramics) according to the different tools and processing materials. The disadvantage of the grinding wheel cutting method is that the stress during the processing is relatively large, especially the soft knife cutting process. The laser cutting method is divided into laser ablation process (laser instantaneous high temperature vaporization material) and laser hidden cutting process (laser modification causes the cutting path to deteriorate and crack naturally) according to the processing principle. The disadvantages of the laser ablation process are slow processing efficiency, high processing cost, high temperature during the process, and materials such as bonding glue are easy to burn. The disadvantage of the laser hidden cutting process is that it has high requirements on the surface roughness and thickness of the cutting material, and one device cannot be compatible with multiple materials.
[0030] Since the temporary bonding glue in the composite structure is flammable, the composite structure cannot be cut using the laser ablation process; and the bonding force of the temporary bonding glue is relatively weak. If a grinding wheel cutting process is used, the glue layer will fall off, causing the ultra-thin silicon wafer 100 to separate from the glass. In addition, due to the material of the temporary bonding glue itself, the laser hidden cutting process cannot process it; since the silicon wafer is ultra-thin, it cannot naturally crack after the laser hidden cutting process, and is not applicable. In other words, the existing cutting methods are not applicable to the above-mentioned composite structure. Therefore, the present embodiment improves the existing cutting method to be applicable to the cutting of the composite structure of the ultra-thin silicon wafer 100 and the glass carrier.
[0031] The cutting method of the composite structure of the ultra-thin silicon wafer and the carrier of this embodiment comprises the following steps:
[0032] S100, please refer to Figure 3 , the front side of the composite structure is cut by a grinding wheel cutting process, and the ultra-thin silicon wafer 100 and the bonding adhesive layer 200 are completely cut through at the cutting position, forming a scratch 700. Of course, in order to facilitate the fixing of the composite structure, before the front side of the composite structure is cut by a grinding wheel cutting process, a first processing carrier film 400 can be pasted on the back side of the composite structure, and after the front side of the composite structure is cut, the first processing carrier film 400 can be removed from the back side of the composite structure.
[0033] Since the soft knife cutting process is generally used to cut hard materials and the cutting blade 600 used therein is relatively thick, it is not suitable for cutting the ultra-thin silicon wafer 100 and the bonding adhesive layer 200 in this embodiment; therefore, in this embodiment, the grinding wheel cutting process adopts a hard knife cutting process, and the cutting blade 600 used in the hard knife cutting process is preferably an ultra-thin hard knife cutting blade. In this embodiment, the ultra-thin hard knife cutting blade is made of diamond material (i.e., a diamond cutting blade), and the thickness of the diamond cutting blade is 20μm to 30μm.
[0034] In order to reduce the stress generated during the grinding wheel cutting process and avoid damaging the ultra-thin silicon wafer 100, this embodiment also reduces the rotation speed and feed rate of the cutting blade 600 when cutting the front side of the composite structure using the grinding wheel cutting process. In this embodiment, the rotation speed of the cutting blade 600 is generally 25000r / min to 30000r / min, and the feed rate is generally 5 to 10mm / s.
[0035] S200, please refer to Figure 4The back of the composite structure is cut at the position of the scratch 700 by using a laser cutting process, and the glass carrier at the scratch 700 is cut through to form a plurality of chip particles 900. Since the carrier 300 in this embodiment uses a transparent glass carrier, when the back of the composite structure is cut, the laser cutting position can be accurately aligned with the scratch 700 to avoid cutting deviation.
[0036] In order to facilitate the fixation of the composite structure and the collection of the chip particles 900 formed after cutting, before using the laser cutting process to cut the back side of the composite structure, a second processing carrier film 500 can be pasted on the front side of the composite structure; after the back side of the composite structure is cut, the chip particles 900 formed after cutting the composite structure are removed from the second processing carrier film 500.
[0037] Since the laser ablation process has slow processing efficiency and high processing cost, the high temperature generated during the processing can easily cause the temporary bonding glue to burn. Therefore, in this embodiment, the laser cutting process used to cut the back of the composite structure is a laser hidden cutting process. When the laser hidden cutting process is used to cut the back of the composite structure, the line width of the laser 800 is 1μm to 2μm, and the step distance (that is, the depth of each cutting of the laser 800) is 5μm to 15μm. By reducing the step distance when the laser 800 is cut, the glass carrier can be broken more thoroughly, which facilitates the subsequent separation of the chip particles 900.
[0038] See also Figure 5 When the glass carrier is cut through at the scratch 700, the composite structure is divided into a plurality of chip particles 900, so that subsequent processing steps can be performed. After the processing is completed, the temporary bonding glue and the glass carrier can be removed.
[0039] In this embodiment, the two sides of the composite structure are cut by using a hard knife cutting process and a laser hidden cutting process, respectively, thereby combining the advantages of the above two traditional processes and avoiding the adverse effects of their disadvantages on the composite structure of the ultra-thin silicon wafer 100 and the carrier 300, having high feasibility and fault tolerance, facilitating the cutting operation of the composite structure, and having low cutting cost and high efficiency. In addition, the use of a transparent glass carrier can also facilitate alignment with the scratch 700 on the front when cutting the back side, thereby improving the cutting accuracy.
[0040] The above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.
Claims
1. A method for cutting a composite structure of an ultra-thin silicon wafer and a carrier, characterized in that: The composite structure is formed by temporarily bonding an ultra-thin silicon wafer to a carrier through a temporary bonding adhesive, thereby forming a bonding adhesive layer between the ultra-thin silicon wafer and the carrier; the surface of the ultra-thin silicon wafer of the composite structure is its front side, and the surface of the carrier of the composite structure is its back side; the cutting method comprises the following steps: The front side of the composite structure is cut by a grinding wheel cutting process, and the ultra-thin silicon wafer and the bonding adhesive layer are completely cut through at the cutting point to form scratches; The back side of the composite structure is cut at the position of the scratch by using a laser cutting process, and the carrier at the scratch is cut through to form a plurality of chip particles.
2. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to claim 1, characterized in that: The thickness of the ultra-thin silicon wafer is 5 μm to 50 μm; the thickness of the bonding adhesive layer is 30 μm to 50 μm.
3. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to claim 2, characterized in that: The carrier is a glass carrier; the thickness of the glass carrier is 300 μm to 600 μm.
4. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to claim 1, characterized in that: Before cutting the front side of the composite structure by the grinding wheel cutting process, a first processing carrier film is firstly pasted on the back side of the composite structure, and after the front side of the composite structure is cut, the first processing carrier film is removed from the back side of the composite structure.
5. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to claim 1, characterized in that: Before cutting the back side of the composite structure by laser cutting, a second processing carrier film is firstly pasted on the front side of the composite structure. After the back side of the composite structure is cut, the chip particles formed after cutting the composite structure are removed from the second processing carrier film.
6. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to any one of claims 1 to 5, characterized in that: The grinding wheel cutting process is a hard knife cutting process.
7. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to claim 6, characterized in that: The cutting blade used in the hard knife cutting process is an ultra-thin hard knife cutting blade, and the thickness of the ultra-thin hard knife cutting blade is 20 μm to 30 μm.
8. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to claim 6, characterized in that: When the front side of the composite structure is cut by the grinding wheel cutting process, the rotation speed of the cutting blade is 25000r / min to 30000r / min, and the feed rate is 5 to 10mm / s.
9. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to any one of claims 1 to 5, characterized in that: The laser cutting process used when cutting the back side of the composite structure is a laser hidden cutting process.
10. The method for cutting the composite structure of an ultra-thin silicon wafer and a carrier according to claim 9, characterized in that: When the back side of the composite structure is cut by the laser hidden cutting process, the line width of the laser is 1 μm to 2 μm and the step distance is 5 μm to 15 μm.