Wafer back-end process method

Abstract

The present invention provides a wafer back-end process method, including: S1, providing a wafer, the wafer including a relative front and back; the back of the wafer is fixed on the first mucosa of the first frame of the circumferential belt; cutting and cleaning the wafer; S2, performing automatic optical inspection on the wafer after cutting and cleaning; S3, peeling off a plurality of qualified chips screened by the automatic optical inspection from the first mucosa, and attaching the front of the plurality of qualified chips to the second mucosa of the second frame of the circumferential belt; S4, transferring the wafer attached to the second mucosa to a wafer boat box; S5, packing the wafer boat box. Since the front of the wafer is attached to the second mucosa, the front of the wafer is protected by the second mucosa to prevent particles from damaging the surface of the wafer during the transfer and transportation of the wafer; it can effectively improve the capacity of wafer reconstruction and reduce the impact of particles on the surface of the shipped wafer. The cleaning and defect sorting processes after sorting are removed, and the crushing injury during chip defect sorting is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of integrated circuit manufacturing, and in particular relates to a wafer back-end process method. Background Art

[0002] Wafer back-end refers to the process of packaging and testing. In the packaging and testing factory, the round wafer is cut into individual chip particles, the terminal test is completed, and the chip products are shipped out of the factory. The back-end process usually includes: packaging processes such as thinning, dicing, sorting, and terminal testing.

[0003] In an existing wafer back-end process, the back of the wafer is fixed on a blue film with a peripheral band frame, and the front of the wafer is exposed to the process environment. Since the front of the wafer is exposed to the process environment, there may still be residual particles after cutting and cleaning, or tiny particles in the process environment may fall on the exposed front of the wafer. These residual particles will damage the front of the wafer during the wafer transfer and transportation process, reducing the qualified rate of chips on the wafer. Summary of the invention

[0004] The purpose of the present invention is to provide a wafer back-end process method. Since the front side of the wafer is attached to the second mucosa, the front side of the wafer is protected by the second mucosa to prevent particles from damaging the surface of the wafer during the transfer and transportation of the wafer; it can effectively improve the capacity of wafer reconstruction and reduce the impact of particles on the surface of the shipped wafer. The cleaning and defect sorting processes after sorting are removed, reducing the pressure damage during chip defect sorting.

[0005] The present invention provides a wafer back-end process method, comprising:

[0006] S1, providing a wafer, wherein the wafer comprises a front side and a back side opposite to each other; the back side of the wafer is fixed on a first adhesive film of a first frame of a peripheral belt; and the wafer is cut and cleaned;

[0007] S2, performing automatic optical inspection on the wafer after cutting and cleaning;

[0008] S3, peeling off the plurality of qualified chips screened by automatic optical detection from the first mucosa, and attaching the front faces of the plurality of qualified chips to the second mucosa of the second frame of the peripheral band;

[0009] S4, transferring the wafer attached to the second mucosa into a wafer boat box;

[0010] S5, packing the wafer boat box.

[0011] Furthermore, the wafer includes an image sensor wafer, which includes a substrate, a circuit layer, a filter layer and a microlens layer from bottom to top; a plurality of photodiodes are formed in the substrate; the side of the wafer where the microlens layer is located is the front side, and the side of the wafer where the substrate is away from the circuit layer is the back side.

[0012] Furthermore, in step S1, the wafer is cut by laser and / or blade; first, the wafer is cut row by row along the cutting path by laser, and in the thickness direction of the wafer, the laser sequentially cuts the microlens layer, the filter layer and the circuit layer until the substrate is exposed; then, the blade is used to cut through the substrate row by row.

[0013] Furthermore, the laser cutting specifically includes: providing a laser beam machine, the laser beam machine including a laser emitter, a chuck table and a moving mechanism; the chuck table fixes the wafer, and the moving mechanism drives the wafer fixed on the chuck table to move;

[0014] The blade cutting specifically includes: providing a cutting machine, the cutting machine including a motor, a main shaft, and a hub and the blade which are sequentially sleeved on the main shaft; the blade is fixed on the radial circumferential edge of the hub, the motor drives the main shaft to rotate, and drives the blade to rotate through the hub to cut through the substrate.

[0015] Furthermore, in step S2, the automatic optical inspection includes: the wafer appearance inspection, particle appearance defect inspection, and optical inspection of patch and wire bonding inspection.

[0016] Furthermore, the original size of the wafer is 12 inches; in step S3, all qualified chips attached to the second mucosa are arranged according to a wafer of a predetermined size, and the predetermined size includes: any one of 12 inches, 8 inches and 6 inches.

[0017] Furthermore, the wafer provided in step S1 is a wafer that has been functionally screened, and functionally qualified chips and functionally unqualified chips are displayed on the wafer map;

[0018] In step S2, the automatic optical inspection performs appearance inspection only on the chips with qualified functions.

[0019] Furthermore, in step S3, unqualified chips screened by automatic optical detection are left on the first mucosa.

[0020] Furthermore, in step S3, the qualified chip is flipped over by using a flipping device, and the front side of the qualified chip is bonded to the second adhesive film by using a mounting device.

[0021] Furthermore, the wafer includes: an integrated circuit wafer and a force-sensitive device wafer.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides a wafer back-end process method, including: S1, providing a wafer, the wafer including a relative front and back; the back of the wafer is fixed on the first mucosa of the first frame of the circumferential belt; cutting and cleaning the wafer; S2, performing automatic optical inspection on the wafer after cutting and cleaning; S3, peeling off a plurality of qualified chips screened by the automatic optical inspection from the first mucosa, and attaching the front of the plurality of qualified chips to the second mucosa of the second frame of the circumferential belt; S4, transferring the wafer attached to the second mucosa to a wafer boat box; S5, packing the wafer boat box. Since the front of the wafer is attached to the second mucosa, the front of the wafer is protected by the second mucosa to prevent particles from damaging the surface of the wafer during the transfer and transportation of the wafer; it can effectively improve the capacity of wafer reconstruction and reduce the impact of particles on the surface of the shipped wafer. The cleaning and defect sorting processes after sorting are removed, and the crushing injury during chip defect sorting is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a schematic diagram of an existing wafer back-end process.

[0025] Figure 2 Schematic diagram of a wafer back-end process method according to an embodiment of the present invention.

[0026] Figure 3 Schematic diagram of the wafer back-end process method according to an embodiment of the present invention.

[0027] Figure 4 It is a schematic diagram of cutting a wafer fixed on a first mucous film in a wafer back-end process method according to an embodiment of the present invention.

[0028] Figure 5 It is a schematic diagram of wafer sorting and re-fixing the front side of the qualified chip on the second adhesive film in the wafer back-end process method of an embodiment of the present invention.

[0029] The reference numerals are as follows:

[0030] 11 - substrate; 12 - circuit layer; 13 - filter layer; 14 - microlens layer; 21 - first frame; 22 - first mucous membrane; 31 - second frame; 32 - second mucous membrane. DETAILED DESCRIPTION

[0031] As described in the background art, in an existing wafer back-end process, the front side of the wafer is exposed to the process environment, and particles may damage the front side of the wafer during the wafer transfer and transportation process, thereby reducing the qualified rate of chips on the wafer.

[0032] Specifically, Figure 1As shown, a wafer is provided, the back of the wafer is fixed on a blue film, the front of the wafer is exposed to the process environment, the wafer fixed on the blue film is cut and cleaned after cutting; then, the chip is functionally tested and sorted and cleaned after sorting; then, the wafer is scanned by automatic optical inspection (AOI); then, the chip is defect-sorted, and unqualified chips are removed or marked; then, the wafer on the blue film is moved to a wafer boat; then, the wafer boat is packaged and shipped. During the whole process, the front of the wafer is exposed to the process environment, and the residual particles will damage the front of the wafer during the wafer transfer process and transportation process, reducing the qualified rate of the chips on the wafer.

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in a very simplified form and use an inaccurate scale, which is only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0034] For ease of description, some embodiments of the present application may use spatially relative terms such as "above", "below", "top", "below", etc. to describe the relationship between one element or component and another (or other) elements or components as shown in the various figures of the embodiments. It should be understood that in addition to the orientations described in the drawings, the spatially relative terms are also intended to include different orientations of the device in use or operation. For example, if the device in the drawings is turned over, the elements or components described as being "below" or "below" other elements or components will subsequently be positioned as being "above" or "above" other elements or components. The terms "first", "second", etc. below are used to distinguish between similar elements and are not necessarily used to describe a specific order or time sequence. It is to be understood that these terms used in this way are interchangeable where appropriate.

[0035] The embodiment of the present invention provides a wafer back-end process method, such as Figure 2 and Figure 3 As shown, including:

[0036] S1. Provide a wafer, wherein the wafer includes a front side and a back side opposite to each other; fix the back side of the wafer on a first adhesive film of a first frame of a peripheral belt; cut and clean the wafer;

[0037] S2, performing automatic optical inspection on the cut and cleaned wafers;

[0038] S3, peeling off the multiple qualified chips screened by automatic optical detection from the first mucosa, and attaching the front faces of the multiple qualified chips to the second mucosa of the peripheral band second frame;

[0039] S4, transferring the wafer bonded to the second mucosa into a wafer boat box;

[0040] S5. Pack the crystal boat box.

[0041] The steps of the wafer back-end process method according to the embodiment of the present invention are described in detail below with reference to the accompanying drawings.

[0042] like Figure 4 As shown, step S1, providing a wafer, the wafer including a front side and a back side opposite to each other; fixing the back side of the wafer on a first adhesive film 22 of a first peripheral band frame 21; cutting and cleaning the wafer fixed on the first adhesive film 22.

[0043] The original size of the wafer can be provided according to actual conditions, and the original size of the wafer can be, for example, 12 inches or other suitable sizes. The wafer is, for example, an image sensor wafer, and the wafer includes a substrate 11, a circuit layer 12, a filter layer 13 and a microlens layer 14 from bottom to top. The side of the wafer where the microlens layer 14 is located is the front side, and the side of the substrate 11 of the wafer away from the circuit layer 12 is the back side. A plurality of photodiodes are formed in the substrate 11, and the plurality of photodiodes are arranged in rows and columns of a pixel array. The circuit layer 12 includes a dielectric layer and a metal layer located in the dielectric layer. The dielectric layer is, for example, a low dielectric insulating film formed by a film of an inorganic material such as SiOF or BSG (SiOB), or a film of an organic material such as a polyimide-based or polyparaxylene-based polymer. Metal wiring is formed in the dielectric layer for connecting pixel signals. The filter layer 13 covers the circuit layer 12, and the filter layer 13 includes a red filter, a green filter, and a blue filter; the red filter, the green filter, and the blue filter are correspondingly arranged above the photodiode. The microlens layer 14 is located above the filter layer 13, and the microlens is configured to guide the incoming light to pass through the corresponding filter and reach the corresponding photodiode. The present invention does not limit the type of wafer. In other examples, the wafer can be various device wafers, such as integrated circuit wafers and force-sensitive MEMS (micro-electromechanical systems) device wafers.

[0044] Laser and / or blade are used to cut wafers; first, laser is used to cut wafers line by line along the cutting path, and in the thickness direction of the wafer, the laser cuts the microlens layer, the filter layer and the circuit layer in sequence until the substrate is exposed; then the blade is used to cut through the substrate line by line. Laser cutting specifically includes: providing a laser beam machine, which includes a laser transmitter, a chuck table and a moving mechanism; the chuck table fixes the wafer, and the moving mechanism drives the wafer fixed on the chuck table to move; blade cutting specifically includes: providing a cutting machine, which includes a motor, a main shaft, and a hub and a blade sequentially mounted on the main shaft; the blade is fixed to the radial circumferential edge of the hub, and the motor drives the main shaft to rotate, which drives the blade to rotate through the hub to cut through the substrate.

[0045] S2, automatic optical inspection of the cut wafers. The wafers provided in step S1 are, for example, wafers that have been screened for function, and functionally qualified chips and functionally unqualified chips are displayed on the wafer map. In step S2, the automatic optical inspection performs appearance inspection only on functionally qualified chips.

[0046] Automatic optical inspection includes: wafer appearance inspection, particle appearance defect inspection, and optical inspection of die and wire bonding inspection.

[0047] S3, such as Figure 4 and Figure 5 As shown, multiple qualified chips screened by automatic optical detection are peeled off from the first mucosa 22, and the front sides of multiple qualified chips are attached to the second mucosa 32 of the second frame 31 of the circumferential band, that is, the wafers are sorted and re-filmed. The qualified chips can be flipped using a flipping device, and the front sides of the qualified chips can be attached to the second mucosa 32 using a mounting device. All qualified chips attached to the second mucosa 32 after sorting can be arranged according to a predetermined size wafer, and the predetermined size can be, for example, any one of 12 inches, 8 inches and 6 inches and other suitable sizes. The size of the predetermined size is set according to market demand. The unqualified chips screened by automatic optical detection are left on the first mucosa 22. Sorting is usually performed using a sorting machine, which classifies and separates the chips according to certain rules by optical detection and mechanical sorting.

[0048] S4. Transfer the wafer attached to the second adhesive film 32 into the wafer boat box. Specifically, the wafer on the second adhesive film 32 with the second frame 31 can be transferred into the wafer boat box by a robot. Since the front side of the wafer (which is also the front side of the qualified chip) is fixed on the second adhesive film 32 and protected by the second adhesive film 32, even if there are unavoidable residual particles during the wafer transfer process, it will not affect the product.

[0049] S5. Pack the crystal boat box.

[0050] The present invention is a method for shipping a chip by attaching the front side of the chip to a mucous membrane, which can effectively improve the capacity of wafer reconstruction and reduce the impact of particles on the surface of the shipped wafer. It prevents particles from damaging the surface of the wafer during the transfer and transportation of the wafer. The movement of particles in the wafer boat box caused by vibrations and bumps during product transportation will not affect the wafer surface.

[0051] Figure 1 The figure is a schematic diagram of an existing wafer back-end process. Figure 2 FIG. 1 is a schematic diagram of a wafer back-end process method according to an embodiment of the present invention. Figure 1 and Figure 2 As shown, Figure 1Compared with the existing wafer back-end process method, the present invention reduces the cleaning and defect sorting steps after sorting. During chip defect sorting, silicon slag generated by the chip adheres to the suction nozzle, causing pressure damage to the chip surface that is subsequently sucked up by the suction nozzle; the present invention reduces the defect sorting steps, reduces pressure damage during chip defect sorting, and reduces particles on the surface of shipped products. In actual tests, the number of particles on the wafer surface of all wafer reconstruction products shipped to customers can reach 0.

[0052] In summary, the present invention provides a wafer back-end process method, including: S1, providing a wafer, the wafer including a relative front and back; the back of the wafer is fixed on the first mucosa of the first frame of the circumferential belt; cutting and cleaning the wafer; S2, performing automatic optical inspection on the wafer after cutting and cleaning; S3, peeling off a plurality of qualified chips screened by automatic optical inspection from the first mucosa, and attaching the front of the plurality of qualified chips to the second mucosa of the second frame of the circumferential belt; S4, transferring the wafer attached to the second mucosa to a wafer boat box; S5, packing the wafer boat box. Since the front of the wafer is attached to the second mucosa, the front of the wafer is protected by the second mucosa to prevent particles from damaging the surface of the wafer during the transfer and transportation of the wafer; it can effectively improve the capacity of wafer reconstruction and reduce the impact of particles on the surface of the shipped wafer. The cleaning and defect sorting processes after sorting are removed, reducing the pressure damage during chip defect sorting.

[0053] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the method disclosed in the embodiment, since it corresponds to the device disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0054] The above description is only a description of the preferred embodiment of the present invention, and is not any limitation on the scope of rights of the present invention. Any technical personnel in this field can make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A wafer back-end process method, characterized in that: include: S1. providing a wafer, wherein the wafer comprises a front side and a back side opposite to each other; The back side of the wafer is fixed on the first mucous membrane of the first frame of the peripheral belt; the wafer is cut and cleaned; S2, performing automatic optical inspection on the wafer after cutting and cleaning; S3, peeling off the plurality of qualified chips screened by automatic optical detection from the first mucosa, and attaching the front faces of the plurality of qualified chips to the second mucosa of the second frame of the peripheral band; S4, transferring the wafer attached to the second mucosa into a wafer boat box; S5, packing the wafer boat box.

2. The wafer back-end process method according to claim 1, characterized in that: The wafer includes an image sensor wafer, which includes a substrate, a circuit layer, a filter layer and a microlens layer from bottom to top; a plurality of photodiodes are formed in the substrate; the side of the wafer where the microlens layer is located is the front side, and the side of the wafer where the substrate is away from the circuit layer is the back side.

3. The wafer back-end process method according to claim 2, characterized in that: In step S1, the wafer is cut by laser and / or blade. The laser is first used to cut the wafer line by line along the cutting path. In the thickness direction of the wafer, the laser sequentially cuts the microlens layer, the filter layer and the circuit layer until the substrate is exposed. Then, the blade is used to cut through the substrate line by line.

4. The wafer back-end process method according to claim 3, characterized in that: The laser cutting specifically comprises: providing a laser beam machine, the laser beam machine comprising a laser emitter, a chuck table and a moving mechanism; the chuck table fixes the wafer, and the moving mechanism drives the wafer fixed on the chuck table to move; The blade cutting specifically includes: providing a cutting machine, the cutting machine including a motor, a main shaft, and a hub and the blade which are sequentially sleeved on the main shaft; the blade is fixed on the radial circumferential edge of the hub, the motor drives the main shaft to rotate, and drives the blade to rotate through the hub to cut through the substrate.

5. The wafer back-end process method according to claim 1, characterized in that: In step S2, the automatic optical inspection includes: the wafer appearance inspection, particle appearance defect inspection, and optical inspection of patch and wire bonding inspection.

6. The wafer back-end process method according to claim 1, characterized in that: The original size of the wafer is 12 inches. In step S3, all qualified chips attached to the second mucosa are arranged according to a wafer of a predetermined size, and the predetermined size includes any one of 12 inches, 8 inches and 6 inches.

7. The wafer back-end process method according to claim 1, characterized in that: The wafer provided in step S1 is a wafer that has been screened for function, and functionally qualified chips and functionally unqualified chips are displayed on the wafer map; In step S2, the automatic optical inspection performs appearance inspection only on the chips with qualified functions.

8. The wafer back-end process method according to claim 1, characterized in that: In step S3, unqualified chips screened by automatic optical detection are left on the first mucosa.

9. The wafer back-end process method according to claim 1, characterized in that: In step S3, the qualified chip is flipped over by using a flipping device, and the front side of the qualified chip is attached to the second adhesive film by using a mounting device.

10. The wafer back-end process method according to claim 1, characterized in that: The wafers include: integrated circuit wafers and force-sensitive device wafers.

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