A method for laser grooving of edge aligned wafers and edge aligned wafers
By covering the defective parts of the edge-flush wafer with a light-shielding adhesive film, the problem of film damage during laser grooving was solved, thus ensuring airtightness and improving product quality during the laser grooving process.
Patent Information
- Application Number
- CN202610431717.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-02
- Publication Date
- 2026-08-25
AI Technical Summary
During the laser grooving process, the adhesive film on the edge-aligned wafer is exposed to the laser, which leads to the risk of damage, affects the airtightness of vacuum adsorption, and increases the product scrap rate.
A light-shielding film is used to cover the defective parts of the edge-aligned wafer. A laser is used to create grooves on the edge-aligned wafer. The light-shielding film reflects or absorbs the laser, preventing the film from being damaged.
This reduces the risk of the adhesive film being burned by the laser, ensures the airtightness of the vacuum adsorption during the laser grooving process of the edge-flush wafer, and reduces the product scrap rate.
Smart Images
Figure CN122641276A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of wafer processing technology, and in particular to a method for laser grooving of edge-aligned wafers and an edge-aligned wafer. Background Technology
[0002] A wafer is a silicon wafer obtained by diamond wire cutting a near-cylindrical silicon ingot obtained through the single-crystal pulling process. To facilitate positioning and cutting in subsequent processes, a side or tapered notch is usually cut into the side of the silicon ingot. Therefore, the wafer is not a regular circle when performing subsequent processes, but rather a flush-edge wafer or a tapered notch V-groove wafer.
[0003] Flush-edge or V-groove wafers help determine the wafer placement position during processing, clarify the single crystal growth direction, and facilitate alignment of crystal orientation during grooving and cutting. At the same time, in automated manufacturing processes, their flush-edge or V-groove can serve as markers to facilitate gripping by robotic arms, simplify the process, and reduce or avoid contamination and damage to the wafer.
[0004] However, in the actual laser grooving process, the back film of the flush-edge wafer or V-groove wafer is exposed to the laser due to the lack of part of the silicon substrate. The back film is the part that is in direct contact with the worktable for vacuum adsorption of the wafer. Direct exposure to the laser will create a risk of damage to the film. If the film is burned and damaged by the laser, it will further cause insufficient vacuum adsorption of the worktable, and the product will be scrapped. Summary of the Invention
[0005] To address the aforementioned technical problems in the prior art, this application provides a method for laser grooving of edge-aligned wafers and an edge-aligned wafer.
[0006] In one technical solution of this application, a method for laser grooving of a wafer with flush edges is provided, which includes: vacuum adsorbing the wafer with flush edges onto the surface of a worktable through an adhesive film on the back of the wafer with flush edges; using a light-shielding adhesive film to fill in the missing part at the flush edge position of the wafer with flush edges, so as to cover the complete circle corresponding to the arc edge part of the wafer with flush edges in a predetermined shape; and using a laser to groove the wafer with flush edges at a predetermined cutting position.
[0007] In another technical solution of this application, this application provides a flush-edge wafer, which includes: a flush-edge wafer body; an adhesive film that is tightly attached to the back side of the flush-edge wafer body so as to vacuum adsorb the flush-edge wafer onto the worktable surface; a light-shielding adhesive film that fills in the missing part of the flush-edge position of the flush-edge wafer and covers the complete circle corresponding to the arc edge portion of the flush-edge wafer in a predetermined shape; and a plurality of grooves that are obtained by grooving the flush-edge wafer at predetermined cutting positions using a laser.
[0008] The beneficial effects that the technical solution of this application can achieve are: when performing the laser grooving process, this application covers the laser path that may be exposed to laser grooving in advance with a light-shielding adhesive film, thereby reducing the risk of the adhesive film being burned and damaged by the laser, thus ensuring the airtightness of the edge-aligned wafers and the vacuum adsorption of the worktable during the laser grooving process, and reducing the scrap rate of the products. Attached Figure Description
[0009] Figure 1 This is a flowchart illustrating the method for edge-to-edge laser grooving of wafers in this application; Figure 2 This is a schematic diagram of a flush-edge wafer; Figure 3 This is a schematic diagram of edge-aligned wafer filling; Figure 4 This is a schematic diagram of a specific implementation of laser grooving for edge-to-edge wafers; Figure 5 , Figure 6 This is a schematic diagram of a specific embodiment of laser grooving for edge-to-edge wafers; Figure 7 This is a schematic diagram of the predetermined cutting position; Figure 8 This is a schematic diagram illustrating the effect of film damage. Detailed Implementation
[0010] The preferred embodiments of this application will now be described in detail with reference to the accompanying drawings, so that the advantages and features of this application can be more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of this application.
[0011] It should be noted that the terms "first," "second," and "third" in the claims and description of this application are used only to distinguish similar objects and should not be construed as describing a specific order or sequence.
[0012] Figure 1 The diagram shows a flowchart of a method for laser grooving of wafers with flush edges.
[0013] In one specific embodiment of this application, Figure 1 The method for edge-aligned wafer laser grooving of this application includes steps S101, S102, and S103.
[0014] exist Figure 1 Step S101 clearly shows that the wafer is vacuum-adsorbed onto the worktable surface through the adhesive film on the back of the wafer. The worktable surface refers to the direct action part of the worktable used for vacuum adsorption of the workpiece that is vacuum fixed with it, or the surface of the part that is in direct contact with the workpiece. Vacuum adsorption of the wafer by the adhesive film on the back of the wafer can achieve the positioning of the wafer.
[0015] In one specific embodiment of this application, the worktable typically performs vacuum adsorption on the wafer by adsorbing the adhesive film on the back side of the wafer with a vacuum chuck. The side of the vacuum chuck that adsorbs the adhesive film on the back side is a hard surface with multiple holes or channels connected to a vacuum pump inside the worktable. When the worktable starts, the vacuum pump extracts the air between the adhesive film and the vacuum chuck, creating a vacuum effect that fixes the wafer to the surface of the vacuum chuck under atmospheric pressure, thus achieving positioning. Good positioning ensures positioning accuracy during subsequent processing steps and improves product yield.
[0016] The adhesive film on the back of the aligned wafer is mainly used to prevent wear and contamination of the wafer back during various processing steps and to facilitate fixation. In particular, it also provides good anti-warping function during the grinding process. Back adhesive films can be categorized according to different processes: grinding adhesive films, dicing adhesive films, encapsulation adhesive films, bonding adhesive films, etc.; and according to the application conditions: anti-adhesion adhesive films, thinning adhesive films, heat-sensitive adhesive films, etc. The back adhesive film in this application can be any of the forms exemplified above. In this application, the back adhesive film is attached to the worktable by a vacuum suction cup and vacuum-adsorbed onto the worktable, thus achieving the fixation of the aligned wafer.
[0017] In a preferred embodiment of this application, the worktable uses a ceramic base, and the vacuum chuck is a porous ceramic vacuum chuck. The combination of the ceramic base and the porous ceramic vacuum chuck improves the airtightness of the worktable. The pore size of the porous ceramic vacuum chuck ranges from 2μm to 75μm, which is finer than traditional vacuum chucks, allowing the chuck surface to adhere more closely to the wafer, thus reducing scratch damage. In terms of material properties, traditional vacuum chucks use aluminum or bronze / brass, while ceramic materials provide higher resistance to acids and alkalis, heat resistance, and wear resistance. Furthermore, ceramic vacuum chucks are lighter and have better insulation properties.
[0018] In one specific embodiment of this application, such as Figure 2The schematic diagram of the flush-edge wafer illustrates the flush-edge wafer formed after a portion of the silicon substrate has been removed. The removed portion of the silicon substrate forms a flush edge, distinct from the curves of the rest of the wafer. Its cross-sectional shape is an irregular circle with a flush edge; correspondingly, the arcuate edge of the flush-edge wafer can form a complete circle. The partial silicon substrate removal process for the flush-edge wafer is performed after high-purity polycrystalline silicon is grown into an approximately cylindrical silicon ingot using the Czochralski process. To facilitate clamping, positioning, and crystal orientation determination of the approximately cylindrical silicon ingot, a flat / notch grinding process is performed. Flat grinding is typically used for silicon ingots with a diameter of less than 200 mm, while notch grinding is typically used for silicon ingots with a diameter greater than 200 mm. The silicon ingot treated with flat grinding is then further cut with diamond wire to form the flush-edge wafer.
[0019] exist Figure 1 Step S102 clearly shows the following steps: using a light-shielding film to fill in the missing portion at the edge of the edge-flush wafer, covering the complete circle corresponding to the arc edge portion of the edge-flush wafer in a predetermined shape; the shape and area of the light-shielding film can at least be sufficient to cover the complete circle corresponding to the arc edge portion of the edge-flush wafer, that is: the missing area formed after the edge-flush wafer is partially removed from the silicon substrate is filled in, so that the edge-flush wafer filled with the light-shielding film can form a complete circle. The technical effect achieved by this step is to completely cover the missing area formed by the partial removal of the silicon substrate on the edge-flush wafer.
[0020] In one specific embodiment of this application, a light-shielding adhesive film is used to fill in the missing portion at the edge of the flush-fit wafer. The filling method involves attaching the light-shielding adhesive film to the missing portion at the edge of the flush-fit wafer. In another specific embodiment of this application, the predetermined shape includes at least two features: its edges can be aligned with the edge of the flush-fit wafer to achieve no gaps between the light-shielding adhesive film and the edge of the flush-fit wafer; and its area is not less than the area required to fill the flush-fit wafer into a complete circle. The technical solution of this embodiment achieves a more thorough coverage effect for the missing portion at the edge of the flush-fit wafer.
[0021] like Figure 3In a specific example of this application, as shown in the schematic diagram of edge-aligning wafer filling, a light-shielding film is used. The film is rectangular in shape, with its long side being equal to and aligned with the edge of the edge-aligning wafer. It also has a certain width, the area of which is sufficient to fill in the missing part at the edge-aligning position of the edge-aligning wafer. Furthermore, it extends to a certain extent along the length of its wide side, so that the light-shielding film in this example has a certain coverage area, allowing the edge-aligning wafer filled with the light-shielding film to form a complete circle.
[0022] Light-shielding films possess the ability to reflect and / or absorb light, including laser beams. Reflection of light, including laser beams, can be achieved through specular reflection and / or diffuse reflection; absorption of light, including laser beams, can be achieved by increasing surface roughness and / or applying a coating material with high absorption rates for light, including laser beams. These methods are merely illustrative of the ability of light-shielding films to reflect and / or absorb light, including laser beams, and do not limit the specific types of light-shielding films. Light-shielding films can be opaque or semi-transparent; for example, using black film can increase the light absorption properties of the film.
[0023] In one specific embodiment of this application, the thickness of the light-shielding film is 110 micrometers, and its components include polyolefins, acrylic acid, etc., and its color is white. This light-shielding film has been verified to significantly reduce laser energy when struck, effectively preventing the laser energy from breaking the support film on the back of the wafer.
[0024] In one specific embodiment of this application, in Figure 1 Step S103, as shown, involves using a laser to align the wafer and create a groove at a predetermined cutting position. The laser grooving process has the advantage of allowing the wafer to cool rapidly after grooving, enabling the material to solidify and quickly form the groove structure. Setting a predetermined cutting position improves the grooving accuracy.
[0025] In one specific embodiment of this application, such as Figure 4 As shown, the predetermined cutting position for laser grooving is set to the complete circular area corresponding to the arc edge of the wafer. Setting the cutting area as a regular circle facilitates precise positioning for laser cutting; and performing laser cutting on the complete circular area corresponding to the arc edge of the wafer can cover the entire area of the wafer, meeting the basic requirements for wafer laser grooving.
[0026] In one specific embodiment of this application, during the laser grooving process (Z), a low-dielectric-constant layer and / or metal are penetrated at a predetermined cutting position by laser grooving, thereby exposing the substrate of the flush-edge wafer. The substrate is primarily a silicon-based matrix with a low-dielectric-constant material distributed on it. Inside integrated circuits, interlayer dielectrics (ILDs) are needed to isolate and support interconnects between different layers. Due to the presence of ILDs, parasitic capacitances inevitably exist between the wires. Using a low-dielectric-constant material (low-K layer) as the ILD can effectively reduce the parasitic capacitance between metal interconnects, thereby improving the stability and operating frequency of the chip. However, as a high-speed logic insulating layer, the low-dielectric-constant material has low mechanical strength, thus posing a risk of film peeling during normal blade cutting. Therefore, this application utilizes laser grooving technology, which uses a highly focused laser beam to emit high-density energy to instantly melt or vaporize part of the wafer material, including the low dielectric constant material layer, and remove difficult-to-cut metals such as copper and its compounds located at the cutting position, thereby reducing the difficulty of subsequent wafer cutting processes and reducing chips, delamination, and other cutting quality problems.
[0027] like Figure 5 , 6 In a specific example of this application, the laser includes a first laser beam and a second laser beam. The first laser beam defines the groove width at a predetermined cutting position, and then the second laser beam performs a groove at the predetermined cutting position with the groove width, penetrating the low dielectric constant layer and / or metal at the predetermined cutting position, thereby exposing the substrate of the flush-edge wafer. Figure 5 , 6 In the diagram, the three horizontal lines represent the low-k layer, and the distributed yellow areas represent the metal objects present in the low-k layer. The first laser beam is a positioning beam, primarily used to determine the required grooving width at the predetermined cutting position, ensuring laser grooving accuracy. By collecting the grooving width data positioned by the first laser beam, the beam width of the second laser beam is controlled for grooving. This not only enables penetration of the low-dielectric-constant layer and / or metal at the predetermined cutting position but also reduces laser operation losses in areas outside the predetermined cutting position.
[0028] In a preferred embodiment of this application, the first laser beam is a narrow beam, and the second laser beam is a wide beam. The narrow beam is used to position the grooving width, and the wide beam is used to penetrate the low dielectric constant layer and / or metal at the predetermined cutting position. For example, the first laser beam can be two beams, which define the grooving width at the predetermined cutting position and delineate two grooves along the grooving width. The two grooves belong to the predetermined cutting position and are located on both sides of the predetermined cutting position, further improving the grooving accuracy and efficiency of the second laser beam. The width of the second laser beam can be controlled and adjusted to the grooving width by, for example, using a beam splitter. A beam splitter is an optical element that achieves a specific reflection and transmission ratio by coating it with a special optical film. Beam splitters include cubic beam splitters, flat beam splitters, polarizing beam splitters, etc. This application mainly uses a beam splitter to control the width of the laser beam so that the second laser beam reaches the cutting width positioned by the first laser beam, without limiting the specific type of beam splitter.
[0029] During the laser-aligned wafer grooving process, the wafer's shape becomes an irregular circle after cutting a portion of the silicon substrate, such as... Figure 7 The schematic diagram of the predetermined cutting position shows that there is no direct positioning relationship between the laser equipment and the worktable. This poses a risk that the laser will pass over the edge of the wafer and directly hit the back adhesive film on the back of the silicon substrate. Due to the ultra-thin nature of the wafer adhesive film, it is prone to burning and breakage when directly exposed to the laser. The broken back adhesive film will compromise the airtightness of the vacuum chuck of the worktable, causing the wafer to become loose relative to the worktable and further preventing the laser grooving process from being performed. This application uses a light-shielding adhesive film to fill in the missing part at the edge of the wafer. When the laser passes over the edge of the wafer, the light-shielding adhesive film effectively blocks the laser, thereby eliminating the risk of the back adhesive film being burned and broken by the laser. This ensures the airtightness of the wafer and the vacuum adsorption of the worktable during the laser grooving process and reduces the product scrap rate.
[0030] A comparative experiment was conducted to verify the feasibility of this application using an example: The experimental group consisted of: a light-shielding adhesive film, a DISCO7161 laser machine, and a wafer with flush edges, including a silicon substrate and a back adhesive film. The light-shielding adhesive film was laid flat on the back adhesive film along the flush edge of the wafer, perpendicular to the irradiation direction of the laser module. After the laser grooving operation, there was no film breakage on the back adhesive film.
[0031] Control group 1: Set to be completely identical except for the non-light-blocking adhesive film; after laser grooving, the adhesive film on the back side showed the following... Figure 8 The back adhesive film is shown to be damaged.
[0032] Control group 2: A translucent adhesive film was used, and all other equipment was identical. After laser grooving, the adhesive film on the back showed the following appearance: Figure 8The back adhesive film is shown to be damaged.
[0033] In one specific embodiment of this application, after the edge-aligned wafer is laser-grooved at a predetermined cutting position, it is further cut using a water jet at the predetermined cutting position. Water jet cutting is a cutting method that utilizes high-pressure water jets. It not only possesses the advantages of high precision and low heat impact, but also exhibits excellent adaptability in cutting various materials, meeting the high precision requirements of wafer manufacturing. Compared to traditional cutting processes, water jet cutting generates almost no heat, effectively avoiding material deformation and stress concentration, which is beneficial for maintaining the physical and chemical properties of the wafer.
[0034] like Figure 2 As shown, this application provides a flush-edge wafer, comprising: a flush-edge wafer body, an adhesive film on the back side of the flush-edge wafer body, a light-shielding adhesive film for filling in the missing portion at the flush-edge position of the flush-edge wafer, and a plurality of grooves obtained by laser grooving. The provided flush-edge wafer can be used to perform the laser grooving method for flush-edge wafers described in any of the above embodiments, and will not be described again here.
[0035] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.
[0036] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0037] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.
Claims
1. A method for laser grooving of edge-flush wafers, characterized in that, include: The wafer is vacuum-adsorbed onto the worktable surface using the adhesive film on the back of the wafer. A light-shielding adhesive film is used to fill in the missing part at the edge position of the edge-flush wafer, so as to cover the complete circle corresponding to the arc edge part of the edge-flush wafer in a predetermined shape. The edge-aligned wafer is slotted at a predetermined cutting position using a laser.
2. The method for laser grooving of edge-flush wafers according to claim 1, characterized in that, The method of using a laser to create grooves at predetermined cutting positions on the edge-flush wafer includes: Within the entire area of the complete circle, a laser is used to create grooves at predetermined cutting positions on the edge-aligned wafer.
3. The method for laser grooving of edge-flush wafers according to claim 1, characterized in that, The predetermined shape is either a shape that aligns with the edge of the edge-flush wafer and fills it to form a complete circle, or a shape that aligns with the edge of the edge-flush wafer and is larger than the shape required to fill it to form a complete circle.
4. The method for laser grooving of edge-flush wafers according to claim 1, characterized in that, The method of using laser alignment to cut grooves at predetermined cutting positions on the wafer includes: The laser is used to penetrate the low dielectric constant layer or metal at the predetermined cutting position, thereby exposing the substrate of the flush wafer.
5. The method for laser grooving of edge-flush wafers according to claim 4, characterized in that, The laser includes a first laser beam and a second laser beam, and The step of using the laser to penetrate the low dielectric constant layer and / or metal at the predetermined cutting position, thereby exposing the substrate of the flush-edge wafer, includes: The first laser beam is used to define the groove width at the predetermined cutting position; The second laser beam is used to create a grooving at the predetermined cutting position with the grooving width, thereby penetrating the low dielectric constant layer and / or metal at the predetermined cutting position to expose the substrate of the flush wafer.
6. The method for laser grooving of edge-flush wafers according to claim 5, characterized in that, The first laser beam is a narrow beam, and the second laser beam is a wide beam.
7. The method for laser grooving of edge-flush wafers according to claim 1, characterized in that, Also includes: After the edge-flush wafer is slotted at a predetermined cutting position using a laser, the edge-flush wafer is cut at the predetermined cutting position using a water jet.
8. The method for laser grooving of edge-flush wafers according to claim 1, characterized in that, The method of using a light-shielding adhesive film to fill in the missing portion at the edge-flush position of the wafer includes: The light-shielding adhesive film is adhered to the defective portion at the edge of the wafer.
9. The method for laser grooving of edge-flush wafers according to claim 1, characterized in that, The thickness of the light-shielding film is 110 micrometers.
10. A flush-edge wafer, characterized in that, include: Edge-flush wafer body; The adhesive film is tightly adhered to the back side of the flush-edge wafer body so as to vacuum adsorb the flush-edge wafer onto the worktable surface. A light-shielding film that fills in the missing portion at the edge of the edge-flush wafer and covers the complete circle corresponding to the arc edge portion of the edge-flush wafer in a predetermined shape. Multiple slots are created by using a laser to cut slots at predetermined cutting positions on the edge-aligned wafer.