Wafer cutting and die singulation method

Abstract

The application provides a wafer cutting and chip sorting method, which comprises the following steps: S1, providing a wafer, the back surface of the wafer is pasted on a back surface adhesive film; S2, pasting a transparent cutting film on the front surface of the wafer; S3, laser scribing the wafer with the film on the front surface, and cutting the wafer to a partial depth by using a laser; S4, scribing the wafer with the film on the front surface by using a blade, and cutting the wafer to a remaining depth by using the blade; S5, sorting the chips with the film on the front surface; and S6, lifting the cutting film on each chip on the blue film. The cutting (scribing) and sorting processes are all protected by the film on the front surface, which can effectively prevent the damage to the chip surface caused by the chipping and splashing generated during the cutting of the chip, improve the cutting quality, help to improve the strength and reliability of the chip, prevent the chip surface from being pressed by a suction nozzle during the sorting of the chip, and improve the sorting yield of the chip. The chip surface can be prevented from chipping, damaging and staining, the cutting surface can be effectively ensured to be complete, the chip surface can be protected, the yield loss can be reduced, and the product yield can be improved.

Description

Technical Field

[0001] This invention belongs to the field of integrated circuit manufacturing technology, specifically relating to a wafer dicing and chip sorting method. Background Technology

[0002] Wafer dicing separates a whole wafer into individual chips. The dicing process can result in contamination, chipping, and damage on the wafer or chip. Contamination refers to hard-to-remove contaminants such as silicon dust and oil particles generated during component movement. Chipping refers to material breakage or loss along the dicing chute, particularly at the edges of the chip's functional areas, forming irregular pits that directly lead to chip failure. Damage refers to the damage to the chip surface caused by spatter such as silicon slag or metal particles generated during dicing.

[0003] Chip sorting is a crucial step in semiconductor manufacturing, involving the automatic classification and grading of chips based on parameters such as electrical performance, optical characteristics, or physical dimensions. During wafer dicing, the chips may generate silicon dross due to the external force of the dicing process. During chip sorting, the pick-up nozzle detaches the chip from the blue film, leading to issues such as silicon dross shedding, microcracks, and chipping, generating new debris. Silicon dross falling during sorting damages the chip surface. Furthermore, the silicon dross generated by the chips may adhere to the pick-up nozzle, causing surface damage to chips picked up by subsequent nozzles. Summary of the Invention

[0004] The purpose of this invention is to provide a wafer dicing and chip sorting method. Both the wafer dicing (digging) and sorting processes are protected by a front-side film, effectively preventing chip damage caused by chip chipping and spatter during dicing; and preventing pressure damage to the chip surface from the pick-up nozzle during chip sorting, thus improving chip sorting yield. This method prevents chip chipping, damage, and contamination of the chip surface, effectively ensuring the integrity of the diced surface, protecting the chip surface, reducing yield loss, and improving product yield.

[0005] This invention provides a wafer dicing and chip sorting method, comprising the following steps:

[0006] S1. A wafer is provided, the back side of which is attached to a back adhesive film;

[0007] S2. A transparent dicing film is attached to the front side of the wafer, i.e., a film is attached to the front side.

[0008] S3. Front-side laser scribing with a film, using laser cutting to cut a portion of the depth of the wafer;

[0009] S4. The front-side blade is used to dicing the wafer to the remaining depth, stopping at the back-side adhesive film.

[0010] S5. Front-side film-coated chip sorting: Using a suction nozzle, the chips with front-side film after dicing are picked up from the wafer and placed on the blue film.

[0011] S6. Peel off the cutting film on each chip on the blue film.

[0012] Furthermore, the cutting film comprises a stacked base film and an adhesive layer, and the light transmittance of the cutting film is <80%.

[0013] Furthermore, the thickness range of the cutting film is 65μm~90μm; the thickness range of the base film is 50μm~70μm; and the thickness range of the adhesive layer is 15μm~20μm.

[0014] Furthermore, the adhesive layer is made of heat-sensitive or cold-sensitive acrylic adhesive, and the adhesive strength range of the adhesive layer is 0.5 N / 25 mm to 5 N / 25 mm; the base film is made of at least one of polyvinyl chloride, polyolefin and polyester.

[0015] Furthermore, the cutting membrane is pressure-sensitive, ready to use upon application, and does not require ultraviolet irradiation or heat curing during application.

[0016] Furthermore, the wafer includes a substrate and a circuit layer located on the substrate; the circuit layer includes a dielectric layer and a metal layer located in the dielectric layer.

[0017] Furthermore, in step S3, a laser is used to cut the circuit layer of a preset width line by line along the scribe line to expose the substrate and form trenches.

[0018] Furthermore, in step S4, a blade is used to cut the substrate below the trench line by line along the trajectory of the trench, cutting through the substrate and stopping at the back adhesive film.

[0019] Furthermore, in step S6, a peeling machine is used to peel off the cutting film on each chip on the blue film.

[0020] Furthermore, after step S6, the method further includes: performing automatic optical inspection on the wafer, automatically checking for chip appearance defects through an optical system and image processing algorithms, and detecting and identifying minute defects in the chip.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention provides a wafer dicing and chip sorting method, comprising: S1, providing a wafer, wherein the back side of the wafer is adhered to a back adhesive film; S2, attaching a transparent dicing film, i.e., a front-side film, to the front side of the wafer; S3, laser dicing the front-side film-coated wafer, using a laser to cut a portion of the wafer's depth; S4, blade dicing the front-side film-coated wafer, using a blade to cut the remaining depth of the wafer, stopping at the back adhesive film; S5, sorting the front-side film-coated chips, using a suction nozzle to pick up the diced front-side film-coated chips from the wafer and place them on a blue film; S6, peeling off the dicing film from each chip on the blue film.

[0023] This invention involves attaching a transparent dicing film to the front side of a wafer, performing front-side laser scribing with the film, front-side blade scribing with the film, and front-side chip sorting with the film. Both the dicing (dicing) and sorting processes are protected by the front-side film, effectively preventing chip damage and spatter during dicing from affecting the chip surface, improving dicing quality, and contributing to increased chip strength and reliability. It also prevents pressure damage to the chip surface from the suction nozzle during chip sorting, improving chip sorting yield. This invention prevents chip damage, contamination, and chip surface defects, effectively ensuring the integrity of the diced surface, protecting the chip surface, reducing yield loss, and improving product yield. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a chip in a wafer dicing and chip sorting method according to an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the wafer front side being coated with a dicing film in the wafer dicing and chip sorting method of this invention.

[0026] Figure 3 This is a schematic diagram of chip cutting in the wafer cutting and chip sorting method of this invention.

[0027] Figure 4 This is a schematic diagram of chip sorting in the wafer dicing and chip sorting method of this invention.

[0028] Figure 5 This is a schematic diagram illustrating the removal of the dicing film on a chip in the wafer dicing and chip sorting method of this invention.

[0029] The accompanying figure is labeled as follows:

[0030] 10-Substrate; 20-Dielectric layer; 21-Metal layer; 30-Color filter layer; 40-Microlens layer; 51-Base film; 52-Adhesive layer. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0032] For ease of description, some embodiments of this application may use spatially relative terms such as “above,” “below,” “top,” and “under” to describe the relationship between one element or component and another (or more) elements or components as shown in the accompanying drawings. It should be understood that, in addition to the orientations described in the drawings, spatially relative terms are also intended to include different orientations of the device during use or operation. For example, if the device in the drawings is flipped, it is described as an element or component “below” or “under” other elements or components, and will subsequently be positioned “above” or “on” other elements or components. The terms “first,” “second,” etc., used below are used to distinguish between similar elements and are not necessarily used to describe a particular order or temporal sequence. It should be understood that these terms, as used, may be replaced where appropriate.

[0033] This invention provides a wafer dicing and chip sorting method, including the following steps:

[0034] S1. Provide a wafer, with the back side of the wafer adhered to a back adhesive film;

[0035] S2. Apply a transparent dicing film to the front side of the wafer, i.e., apply a film to the front side;

[0036] S3, front-side laser scribing with film, using laser cutting to cut a portion of the wafer depth;

[0037] S4. Front-side die-cutting with a film-coated blade: the blade cuts the remaining depth of the wafer and stops at the back-side film.

[0038] S5. Front-side film-coated chip sorting: The front-side film-coated chips are picked up from the wafer after dicing using a suction nozzle and placed on the blue film.

[0039] S6. Peel off the cutting film on each chip on the blue film.

[0040] The following describes in detail each step of the wafer dicing and chip sorting method according to an embodiment of the present invention, with reference to the accompanying drawings.

[0041] Step S1, as follows Figure 1As shown, a wafer is provided, with its back side attached to a back adhesive film. The wafer may be an image sensor wafer. Exemplarily, the wafer includes a substrate 10 and a circuit layer located on the substrate; the circuit layer includes a dielectric layer 20 and a metal layer 21 located within the dielectric layer. A color filter layer 30 and a microlens layer 40 are sequentially formed on the dielectric layer 20. Metal interconnect structures and / or bonding pads are formed in the dielectric layer 20.

[0042] Step S2, as follows Figure 1 and Figure 2 As shown, a transparent dicing film is applied to the front side of the wafer, i.e., a front-side film. For example, using a machine with a film-applying function, the transparent dicing film is applied to the front side of the wafer, resulting in clear and distinct dicing lines for easy alignment and cutting. The wafer must be cleaned before applying the film to reduce surface contaminants. The dicing film has a light transmittance of <80% and absorbs laser energy to complete the cutting. The dicing film is heat-resistant, has minimal heat-affected zone during laser grooving, and produces no adhesive residue. The dicing film comprises a laminated base film 51 and an adhesive layer 52. The thickness range of the dicing film is 65μm~90μm; the thickness range of the base film 51 is 50μm~70μm; and the thickness range of the adhesive layer 52 is 15μm~20μm. The adhesive layer 52 can be made of heat-sensitive or cold-sensitive acrylic adhesive. The base film 51 can be made of at least one of polyvinyl chloride, polyolefin, and polyester. Adhesive layer 52 exhibits high adhesion: 0.5 N / 25mm to 5 N / 25mm, ensuring no edge lifting during laser and blade cutting processes and guaranteeing high chip pick-up rates during sorting. The cutting film is pressure-sensitive, ready to use upon bonding, requiring no UV or thermal curing during bonding. The cutting film leaves no adhesive residue upon peeling; the adhesive is removed by UV irradiation, leaving no residue after peeling.

[0043] Step S3, as follows Figure 3 As shown, laser dicing with a film on the front side is used to cut a portion of the wafer's depth using laser cutting. The wafer includes a substrate and a circuit layer on the substrate; the circuit layer includes a dielectric layer and a metal layer within the dielectric layer. A laser cuts the circuit layer of a predetermined width along the dicing traces, exposing the substrate and forming trenches. Multiple dicing traces are pre-defined in a plane parallel to the front side of the wafer, extending along a first and a second direction perpendicular to each other. Viewed from above, the first and second trenches are intersected in a crisscross pattern. During laser cutting, the metal particles / slag generated by the laser can only fall onto the dicing film on the front side of the wafer and cannot contact the chip surface. The laser cutting to form trenches specifically includes: providing a laser beam machine, which includes a laser emitter, a chuck stage, and a moving mechanism; the chuck stage fixes the wafer, and the moving mechanism moves the wafer fixed on the chuck stage.

[0044] Step S4: Dicing with a blade on the front side, cutting the remaining depth of the wafer and stopping at the back adhesive film. The blade cuts the substrate below the trench line by line along the trench's trajectory, penetrating the substrate and stopping at the back adhesive film. During blade cutting, the laser removes the metal layer from the dielectric layer, eliminating mechanical cutting stress and reducing the incidence of surface chipping; furthermore, foreign objects can only fall onto the dicing film on the front side of the wafer and cannot contact the chip surface area. Specifically, blade cutting includes: providing a dicing machine, which includes a motor, a spindle, and a hub and blades sequentially mounted on the spindle; the blades are fixed to the radial circumferential edge of the hub, the motor drives the spindle to rotate, and the hub drives the blades to rotate, cutting the substrate below the trench line by line along the trench's trajectory, penetrating the substrate and stopping at the back adhesive film. The blade material includes diamond, with a diamond particle size of 2μm~3μm.

[0045] Step S5, as follows Figure 4 As shown, chip sorting is performed on the front-side film. A vacuum nozzle picks up the diced chips with the front-side film from the wafer and places them on the blue film. This achieves zero pressure damage in the chip sorting process, which helps improve the chip sorting yield. It prevents pressure damage to the chip surface from the nozzle during chip sorting, thus improving the chip sorting yield. It can also prevent chipping, damage, and contamination on the chip surface.

[0046] Step S6, as follows Figure 5 As shown, the dicing film on each chip is peeled off from the blue film. A peeling machine can be used to peel off the dicing film on each chip from the blue film. Afterwards, automated optical inspection is performed, automatically checking for chip appearance defects using a high-precision optical system and image processing algorithms. It detects and identifies micron-level defects on the chips, such as cracks, missing corners, scratches, foreign matter contamination, or abnormal circuit patterns. In the chip sorting process, automated optical inspection is usually used in conjunction with electrical test data. Good and defective chips are distinguished and marked, providing a basis for subsequent precise sorting.

[0047] This invention provides a wafer dicing and chip sorting method, specifically a surface protection process for wafer dicing and chip sorting to prevent wafer chipping and surface defects. The chip sorting yield of all products is improved by 0.5% to 2% or more, and the surface yield of products in the dicing and sorting processes is improved to 100%.

[0048] In summary, this invention provides a wafer dicing and chip sorting method, comprising: S1, providing a wafer, with the back side of the wafer adhered to a back adhesive film; S2, attaching a transparent dicing film, i.e., a front-side dicing film, to the front side of the wafer; S3, laser dicing with the front-side dicing film, using a laser to cut a portion of the wafer's depth; S4, blade dicing with the front-side dicing film, using a blade to cut the remaining depth of the wafer, stopping at the back adhesive film; S5, sorting the front-side dicing film chips, using a suction nozzle to pick up the diced front-side dicing film chips from the wafer and place them on a blue film; S6, peeling off the dicing film from each chip on the blue film. This invention involves attaching a transparent dicing film to the front side of the wafer, laser dicing with the front-side dicing film, blade dicing with the front-side dicing film, and sorting the front-side dicing film chips. Both the dicing (digging) and sorting processes are protected by a front-side film, effectively preventing chip damage caused by chipping and spatter during dicing, thus improving dicing quality and contributing to increased chip strength and reliability. It also prevents pressure damage to the chip surface from the suction nozzle during sorting, improving chip sorting yield. Furthermore, it prevents chip surface chipping, damage, and contamination, effectively ensuring the integrity of the diced surface, protecting the chip surface, reducing yield loss, and improving product yield.

[0049] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The methods disclosed in the embodiments are described simply because they correspond to the devices disclosed in the embodiments; relevant details can be found in the method section.

[0050] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for wafer dicing and chip sorting, characterized in that, include: S1. A wafer is provided, the back side of which is attached to a back adhesive film; S2. A transparent dicing film is attached to the front side of the wafer, i.e., a film is attached to the front side. S3. Front-side laser scribing with a film, using laser cutting to cut a portion of the depth of the wafer; S4. The front-side blade is used to dicing the wafer to the remaining depth, stopping at the back-side adhesive film. S5. Front-side film-coated chip sorting: The chip with the front-side film after dicing is picked up from the wafer using a suction nozzle and placed on the blue film. S6. Peel off the cutting film on each chip on the blue film.

2. The wafer dicing and chip sorting method as described in claim 1, characterized in that, The cutting film comprises a stacked base film and an adhesive layer, and the light transmittance of the cutting film is <80%.

3. The wafer dicing and chip sorting method as described in claim 2, characterized in that, The thickness range of the cutting film is 65μm~90μm; the thickness range of the base film is 50μm~70μm; and the thickness range of the adhesive layer is 15μm~20μm.

4. The wafer dicing and chip sorting method as described in claim 2, characterized in that, The adhesive layer is made of heat-sensitive or cold-sensitive acrylic adhesive, and the adhesive strength range of the adhesive layer is 0.5 N / 25mm to 5 N / 25mm; the base film is made of at least one of polyvinyl chloride, polyolefin and polyester.

5. The wafer dicing and chip sorting method as described in claim 1, characterized in that, The cutting membrane is pressure-sensitive and ready to use upon application, requiring no ultraviolet radiation or heat curing during application.

6. The wafer dicing and chip sorting method as described in claim 1, characterized in that, The wafer includes a substrate and a circuit layer on the substrate; the circuit layer includes a dielectric layer and a metal layer located in the dielectric layer.

7. The wafer dicing and chip sorting method as described in claim 6, characterized in that, In step S3, the circuit layer of a preset width is cut line by line along the scribe line using a laser to expose the substrate and form trenches.

8. The wafer dicing and chip sorting method as described in claim 7, characterized in that, In step S4, a blade is used to cut the substrate below the trench line by line along the trajectory of the trench, cutting through the substrate and stopping at the back adhesive film.

9. The wafer dicing and chip sorting method as described in claim 1, characterized in that, In step S6, a peeling machine is used to peel off the cutting film on each chip on the blue film.

10. The wafer dicing and chip sorting method as described in claim 1, characterized in that, Step S6 is followed by: performing automatic optical inspection on the wafer, automatically checking for chip appearance defects and detecting and identifying minute defects in the chip through an optical system and image processing algorithm.

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