Wafer transfer method and package structure

Abstract

The present application provides a wafer transfer method and a packaging structure, the wafer transfer method comprising the following steps: setting an adhesive body and a positioning body on a mounting surface of a substrate; placing a wafer in the positioning body, and making the outer edge of the wafer contact a guide surface; vibrating the substrate, so that the wafer slides along the guide surface to a preset position; and pressing the wafer on the adhesive body after the vibration of the substrate stops.The wafer transfer method of the present application firstly positions the wafer through the positioning body around the periphery of the adhesive body, then corrects the position of the wafer through the vibration of the substrate, and finally firmly bonds the wafer and the substrate together through the adhesive body after the correction; the method can improve the position accuracy of the wafer, thereby improving the yield of the semiconductor packaging structure.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and in particular to a wafer transfer method and packaging structure. Background Technology

[0002] Fan-out Wafer Level Package (FOWLP) and Fan-out Panel Level Package (FOPLP) are two packaging technologies that have received widespread attention in recent years. Both FOWLP and FOPLP involve a wafer reassembly step. The general process of wafer reassembly involves dicing the wafer into multiple wafers, transferring the wafers to a carrier substrate, and then fabricating an RDL (Redistribution Layer) on the substrate to expose the I / O electrodes of the wafers. FOPLP, in particular, is considered a breakthrough technology that extends FOWLP and enables highly integrated IC packaging. FOPLP replaces the circular wafer substrate with a larger square substrate (glass or PCB), resulting in higher utilization and lower costs.

[0003] However, in the prior art, after the wafer is transferred to the carrier, the wafer's position may be deviated, which may cause the RDL layer lines to fail to make good contact with the wafer's electrodes, resulting in defective packaged products. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a wafer transfer method that can improve the positioning accuracy of wafers on a substrate and increase the yield of semiconductor packaging structures.

[0005] The present invention also proposes a packaging structure.

[0006] A wafer transfer method according to a first aspect of the present invention includes the following steps:

[0007] An adhesive body and a positioning body are provided on the mounting surface of the substrate, such that: the adhesive body is bonded to the mounting surface, the positioning body is connected to the mounting surface and protrudes relative to the mounting surface, the positioning body surrounds the outer edge of the adhesive body, and the side surface of the positioning body near the adhesive body includes a guide surface, the guide surface gradually approaches the central axis of the positioning body from top to bottom;

[0008] The wafer is placed in the positioning body, and the outer edge of the wafer contacts the guide surface;

[0009] The substrate is vibrated, causing the wafer to slide along the guide surface to a preset position;

[0010] After the vibration of the substrate stops, the wafer is pressed onto the adhesive.

[0011] The wafer transfer method according to a first aspect of the present invention has at least the following advantages: the method first uses a positioning body around the adhesive to initially position the wafer just placed on the adhesive, then corrects the position of the wafer by vibrating the substrate, and after correcting the wafer by vibrating the substrate, the wafer and the substrate are firmly bonded together by the adhesive. Therefore, the wafer transfer method provided by the present invention can improve the positional accuracy of the wafer after bonding with the substrate, thereby improving the yield of semiconductor packaging structures.

[0012] According to some embodiments of the present invention, the vibration of the substrate is generated by sound waves or microwaves applied to the substrate.

[0013] According to some embodiments of the present invention, the wafer transfer method further includes the following steps: while pressing the wafer onto the adhesive, heating the adhesive or irradiating the adhesive with light to enhance the adhesiveness of the adhesive.

[0014] According to some embodiments of the present invention, the substrate is transparent, and the side of the substrate facing away from the mounting surface is the back side. While pressing the wafer onto the adhesive, the wafer transfer method further includes the following steps: irradiating the back side with light so that the light passes through the substrate and irradiates the adhesive, thereby enhancing the adhesion of the adhesive.

[0015] According to some embodiments of the present invention, the wafer transfer method further includes the following steps: releasing the pressure on the wafer, and then applying an adhesive layer on the mounting surface so that the adhesive layer covers the positioning body and the wafer.

[0016] According to a second aspect of the present invention, a packaging structure includes: a substrate having a mounting surface; an adhesive body bonded to the mounting surface; a wafer bonded to the side of the adhesive body opposite to the mounting surface; and a positioning body connected to the mounting surface and protruding relative to the mounting surface, the positioning body surrounding the adhesive body and the wafer, the side surface of the positioning body near the adhesive body including a guide surface, the guide surface abutting against the outer edge of the wafer, the guide surface gradually approaching the central axis of the positioning body from top to bottom.

[0017] The packaging structure according to a second aspect embodiment of the present invention has at least the following advantages: the positioning body surrounding the adhesive body can position the wafer, and since the inner side of the positioning body has a guide surface that gradually approaches the central axis of the positioning body from top to bottom, during the wafer packaging process, the vibration of the substrate can cause the wafer to slide along the guide surface under its own gravity and gradually approach the preset position. Therefore, the accuracy of the wafer's position relative to the substrate in this packaging structure is relatively high.

[0018] According to some embodiments of the present invention, the included angle between the guide surface and the central axis of the positioning body is α, satisfying: 30°≤α≤70°.

[0019] According to some embodiments of the present invention, the width of one side of the positioning body is D, which satisfies: 0.1mm≤D≤1mm.

[0020] According to some embodiments of the present invention, the packaging structure further includes an adhesive layer connected to the mounting surface, the adhesive layer covering the wafer and the positioning body.

[0021] According to some embodiments of the present invention, the adhesive is made of at least one of polyethylene terephthalate and acrylate.

[0022] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0024] Figure 1 This is a schematic diagram of a wafer transfer method according to one embodiment of the present invention;

[0025] Figure 2 This is a top view of the packaging structure in one embodiment of the present invention;

[0026] Figure 3 for Figure 2 A cross-sectional view of the encapsulation structure along section AA;

[0027] Figure 4 This is a schematic diagram of a substrate that has been connected to the adhesive and positioning elements.

[0028] Figure 5 This is a schematic diagram showing the wafer after it has been placed inside the positioning body.

[0029] Figure 6 This is a schematic diagram of a wafer transfer method according to another embodiment of the present invention;

[0030] Figure 7 This is a schematic diagram of the encapsulation structure with an adhesive layer in this invention.

[0031] Figure label:

[0032] 100-Packaging structure, 101-Substrate, 102-Chip, 103-Positioning element, 104-Adhesive element, 105-Adhesive layer;

[0033] 201-Mounting surface, 202-Back side, 203-Guide surface, 204-Central axis, 205-Accommodation space. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0035] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0036] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0037] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0038] Figure 2 This is a top view of a packaging structure 100 according to one embodiment of the present invention. The packaging structure 100 is formed by transferring a wafer onto a substrate using the wafer transfer method of the present invention. Figure 3 for Figure 2 The encapsulation structure is shown in a cross-sectional view along section AA. (Refer to...) Figure 3The packaging structure 100 includes a substrate 101, an adhesive 104, a chip 102, and a positioning body 103. The substrate 101 has a mounting surface 201 and a back surface 202 that face each other. The mounting surface 201 is one end face of the substrate 101 along its thickness direction. Figure 3 The mounting surface 201 is the top surface of the substrate 101. Figure 2 In this design, the positioning body 103 is rectangular, and this rectangular positioning body 103 can be adapted to a rectangular chip 102. (See reference...) Figure 4 The positioning body 103 and the mounting surface 201 together enclose a receiving space 205, which is used to receive the chip 102 and the adhesive 104.

[0039] Reference Figure 3 The adhesive body 104 is bonded to the mounting surface 201. The positioning body 103 is connected to the mounting surface 201 and protrudes relative to the mounting surface 201. The wafer 102 is bonded to the side of the adhesive body 104 opposite to the mounting surface 201. The positioning body 103 surrounds the wafer 102 and also surrounds the adhesive body 104. The surface of the positioning body 103 near the adhesive body 104 includes a guide surface 203. The guide surface 203 gradually approaches the central axis 204 of the positioning body 103 from top to bottom, and the guide surface 203 abuts against the outer edge of the wafer 102. Figure 2 and Figure 3 In the embodiment shown, the guide surface 203 includes four inclined surfaces connected end to end in sequence. The four inclined surfaces abut against the front, rear, left and right edges of the wafer 102 respectively. Each inclined surface satisfies the following condition: the inclined surface gradually approaches the central axis 204 of the positioning body 103 from top to bottom.

[0040] Figure 1 This invention illustrates a wafer transfer method according to one embodiment, which can be used as part of a fan-out panel-level packaging process. Using this method, wafers such as… Figure 2 and Figure 3 The package structure 100 shown. The wafer transfer method includes the following steps:

[0041] S10: An adhesive body 104 and a positioning body 103 are provided on the mounting surface 201 of the substrate 101, such that: the adhesive body 104 is bonded to the mounting surface 201, the positioning body 103 is connected to the mounting surface 201 and protrudes relative to the mounting surface 201, the positioning body 103 surrounds the outer edge of the adhesive body 104, and the side surface of the positioning body 103 near the adhesive body 104 includes a guide surface 203, and the guide surface 203 gradually approaches the central axis 204 of the positioning body 103 from top to bottom;

[0042] S20: Place the wafer 102 inside the positioning body 103, and make the outer edge of the wafer 102 contact the guide surface 203;

[0043] S30: Vibrate the substrate 101 to cause the wafer 102 to slide down the guide surface 203 to a preset position;

[0044] S40: After the vibration of the substrate 101 stops, the wafer 102 is pressed onto the adhesive 104.

[0045] The following is combined with Figure 4 and Figure 5 The above wafer transfer method will be described in detail. Figure 4 The substrate 101 with the adhesive 104 and the positioning body 103 connected is shown, i.e., the product obtained after step S10. Figure 4 As shown. Figure 5 This shows the state after the wafer 102 is placed inside the positioning body 103, that is, the product obtained after step S20. Figure 5 As shown.

[0046] After completing step S10, based on Figure 4 The structure shown allows for the execution of step S20 to transfer the wafer 102 onto the substrate 101. The wafer 102 to be transferred to the substrate 101 is directly derived from a wafer diced. Before dicing, a blue film is attached to the bottom surface of the wafer; after the wafer is diced into multiple wafers 102, the wafers 102 remain attached to the blue film (the blue film is not diced). Subsequently, the wafer 102 can be picked up from the blue film by an electrostatic chuck or a vacuum chuck (the chuck is not shown in the figures) and transferred to the substrate 101 with the electrostatic chuck or vacuum chuck. After the chuck moves onto the substrate 101, it releases the suction on the wafer 102, and the wafer 102 is placed inside the positioning body 103. The wafer 102 is surrounded by the positioning body 103, and the outer edge of the wafer 102 contacts the guide surface 203. It should be noted that the chip 102 mentioned in this invention is located inside the positioning body 103 (or similar description) meaning that the chip 102 is located in the accommodating space 205 enclosed by the positioning body 103.

[0047] After completing step S20, the ideal state is that the chip 102 is located in a preset position, that is, the chip 102 is placed flat inside the positioning body 103, and the center of the chip 102 is located on the central axis 204 of the positioning body 103. Figure 5 The chip 102 on the left side is positioned at the preset location. However, after completing step S20, chip 102 may still be misaligned. Figure 5 The chip on the right side is tilted. The tilt of chip 102 means that the position of chip 102 deviates from the preset position.

[0048] Step S30 aims to reduce this positional deviation. As the guide surface 203 gradually approaches the central axis 204 of the positioning body 103 from top to bottom, the wafer 102 can slide down along the guide surface 203. When the substrate 101 vibrates, the wafer 102 also vibrates. During the vibration of the wafer 102, the raised edge of the wafer 102 can slide down along the guide surface 203 under its own gravity, thereby gradually bringing the wafer 102 closer to the preset position and reducing the deviation between the actual position and the preset position of the wafer 102.

[0049] In some embodiments, the vibration of the substrate 101 can be achieved by emitting microwaves to the substrate 101 to cause it to vibrate; or by emitting sound waves to the substrate 101 to cause it to vibrate. Since the wafer 102 is relatively small (typically between 1mm and 20mm), the advantage of using sound waves or microwaves to drive the substrate 101 to vibrate is that it allows for small-amplitude vibrations of both the substrate 101 and the wafer 102, which are more suitable for correcting the position of the wafer 102. Large-amplitude vibrations may cause the wafer 102 to fall out of the positioning body 103 during the vibration process, because the wafer 102 is not firmly bonded to the adhesive body 104 during steps S20 and S30.

[0050] In some embodiments, step S40 may be performed after the vibration time of the substrate 101 reaches a preset time. Pressing the wafer 102 onto the adhesive 104 can specifically involve using a pressure head (not shown) to press against the top surface of the wafer 102, and then using the pressure head to press the wafer 102 downwards. Step S40 allows the wafer 102 and the adhesive 104 to be in close contact, thereby firmly bonding the wafer 102 and the adhesive 104 together, and thus fixing the wafer 102 relative to the substrate 101. In other embodiments, visual recognition can be used to determine when the substrate 101 should stop vibrating. For example, a user can set up a visual detection device that acquires an image of the wafer 102 and determines whether the wafer 102 is in a preset position. When the visual detection device determines that the wafer 102 is in the preset position, the device used to drive the vibration of the substrate 101 stops operating.

[0051] In summary, the inventive concept of the wafer transfer method provided by this invention is as follows: First, the wafer 102, which has just been placed on the adhesive body 104, is initially positioned using the positioning body 103 around the adhesive body 104. Then, the position of the wafer 102 is corrected by the vibration of the substrate 101. After the wafer 102 is corrected by the vibration of the substrate 101, the wafer 102 and the substrate 101 are firmly bonded together using the adhesive body 104. Therefore, the wafer transfer method provided by this invention can improve the positional accuracy of the wafer 102 after bonding with the substrate 101, thereby improving the yield of the semiconductor packaging structure 100.

[0052] The following section will supplement the content on wafer transfer methods.

[0053] Figure 6 A wafer transfer method according to another embodiment of the present invention is shown. (Refer to...) Figure 6 The wafer transfer method further includes: while pressing the wafer 102 onto the adhesive 104, heating the adhesive 104 or irradiating the adhesive 104 with light, thereby enhancing the adhesiveness of the adhesive 104. More specifically, "enhancing the adhesiveness of the adhesive 104" can specifically refer to curing the adhesive 104. The material of the adhesive 104 includes at least one of polyethylene terephthalate, polyethylene glycol ester, and acrylate.

[0054] After step S20 is completed, the wafer 102 will still be in contact with the adhesive 104; the wafer 102 does not only come into contact with the adhesive 104 during or after step S40. The advantage of this embodiment is that during the process of correcting the position of the wafer 102 by the vibration of the substrate 101 (i.e., during step S30), the adhesive force between the adhesive 104 and the wafer 102 is low, the wafer 102 is not completely fixed to the adhesive 104, and the wafer 102 can still move relative to the adhesive 104. The vibration and slippage of the wafer 102 are not easily hindered by the adhesive 104.

[0055] The specific operation of heating the adhesive 104 can be as follows: heating the substrate 101, and then heating the adhesive 104 through heat conduction between the substrate 101 and the adhesive 104.

[0056] The substrate 101 can be transparent, for example, it can be a transparent glass plate. When the substrate 101 is transparent, if it is necessary to enhance the adhesion of the adhesive 104 by irradiating it with light, the light can be irradiated onto the back surface 202 of the substrate 101, then pass through the substrate 101 and irradiate the adhesive 104. The advantage of this irradiation method is that the area of ​​the adhesive 104 irradiated by the light is relatively large, and the adhesive 104 can be irradiated uniformly by the light. This helps to reduce the adhesion differences between different areas of the adhesive 104 and improve the adhesion effect of the adhesive 104 to the wafer 102. In a specific embodiment, the light used to irradiate the adhesive 104 is ultraviolet light, and correspondingly, the adhesive 104 is configured to have enhanced adhesion after being irradiated by ultraviolet light.

[0057] Reference Figure 7 In some embodiments, the packaging structure 100 further includes an adhesive layer 105 that covers the positioning body 103 and the wafer 102. For example... Figure 7 As shown, the adhesive layer 105 covering the positioning body 103 and the chip 102 specifically means that after the chip 102 is bonded to and fixed to the substrate 101, the top surface of the chip 102 is lower than the top surface of the adhesive layer 105, and the top surface of the positioning body 103 is also lower than the top surface of the adhesive layer 105. The adhesive layer 105 surrounds the periphery of the positioning body 103 and fills the gap between the guide surface 203 and the chip 102. The top surface of the adhesive layer 105 is set as a plane. If the structure obtained after completing step S40 is called a semi-finished product, then covering the positioning body 103 and the chip 102 with the adhesive layer 105 can improve the flatness of the side of the semi-finished product where the chip 102 is located, so as to carry out subsequent packaging steps. Among them, the subsequent packaging steps may include the fabrication of an RDL layer (Redistribution Layer).

[0058] Accordingly, in the case where the encapsulation structure 100 includes an adhesive layer 105, such as Figure 6 As shown, the wafer transfer method further includes step S50: releasing the pressure on the wafer 102, and then setting an adhesive layer 105 on the mounting surface 201 so that the adhesive layer 105 covers the positioning body 103 and the wafer 102.

[0059] The adhesive layer 105 can be fixed to the mounting surface 201 by applying the raw material of the adhesive layer 105 in a fluid state to the mounting surface 201 and then allowing the adhesive layer 105 to cure. The material of the adhesive layer 105 may include at least one of polyimide, silicone, and acrylic.

[0060] The following section provides some additional details about the packaging structure 100.

[0061] If the packaging structure 100 is a fan-out panel-level packaging structure, then the substrate 101 can be set as a rectangle, with a side length of 300mm-1000mm. The substrate 101 can be a transparent glass plate, or it can be a transparent or opaque plate made of other materials.

[0062] The material of the positioning body 103 may include at least one of polytetrafluoroethylene, polystyrene, and polyimide. The positioning body 103 can be disposed on the mounting surface 201 of the substrate 101 in two ways: first, a molded positioning body 103 is fabricated, and then the molded positioning body 103 is bonded to the mounting surface 201 of the substrate 101 by adhesive bonding; or, the raw material of the positioning body 103 is first coated onto the mounting surface 201, and then the material is cured to form the positioning body 103 connected to the mounting surface 201. It should be noted that both the adhesive body 104 and the positioning body 103 used for contacting the wafer 102 are set as insulators to prevent short circuits or other circuit failures in the packaging structure 100.

[0063] Reference Figure 3 To facilitate the slippage of the wafer 102 during vibration of the substrate 101, the angle between the guide surface 203 and the central axis 204 of the positioning body 103 is denoted as α, which satisfies the following condition: 30°≤α≤70°. The single-sided width D of the adhesive body 104 satisfies the following condition: 0.1mm≤D≤1mm. This setting reduces the area of ​​the mounting surface 201 occupied by the adhesive body 104, thus reserving sufficient area for the circuitry to be installed on the wafer 102 and the substrate 101. Furthermore, the height H of the adhesive body 104 satisfies the following condition: 50μm≤H≤200μm. This setting prevents the adhesive body 104 from reducing its positioning effect on the wafer 102 due to insufficient height, and also prevents the adhesive body 104 from being too tall, thereby reducing the overall thickness of the package structure 100 and minimizing its impact on the connection between the wafer 102 and the bonding wires.

[0064] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A wafer transfer method, characterized in that, Includes the following steps: An adhesive body and a positioning body are provided on the mounting surface of the substrate, such that: the adhesive body is bonded to the mounting surface, the positioning body is connected to the mounting surface and protrudes relative to the mounting surface, the positioning body surrounds the outer edge of the adhesive body, and the side surface of the positioning body near the adhesive body includes a guide surface, the guide surface gradually approaches the central axis of the positioning body from top to bottom; The wafer is placed in the positioning body, and the outer edge of the wafer contacts the guide surface; The substrate is vibrated, causing the wafer to slide along the guide surface to a preset position; After the vibration of the substrate stops, the wafer is pressed onto the adhesive.

2. The wafer transfer method according to claim 1, characterized in that, The vibration of the substrate is generated by sound waves or microwaves applied to the substrate.

3. The wafer transfer method according to claim 1, characterized in that, The wafer transfer method further includes the following steps: while pressing the wafer onto the adhesive, heating the adhesive or irradiating the adhesive with light to enhance the adhesiveness.

4. The wafer transfer method according to claim 1, characterized in that, The substrate is transparent, and the side of the substrate facing away from the mounting surface is the back side. The wafer transfer method further includes the following steps: while pressing the wafer onto the adhesive, irradiating the back side with light so that the light passes through the substrate and irradiates the adhesive, thereby enhancing the adhesion of the adhesive.

5. The wafer transfer method according to claim 1, characterized in that, The wafer transfer method further includes the following steps: releasing the pressure on the wafer, and then applying an adhesive layer to the mounting surface so that the adhesive layer covers the positioning body and the wafer.

6. The packaging structure, characterized in that, The package structure is manufactured by the wafer transfer method as described in any one of claims 1 to 5, and includes: The substrate has a mounting surface; An adhesive body is bonded to the mounting surface; The wafer is bonded to the side of the adhesive body opposite to the mounting surface; A positioning body is connected to the mounting surface and protrudes relative to the mounting surface. The positioning body surrounds the adhesive body and the wafer. The side surface of the positioning body near the adhesive body includes a guide surface. The guide surface abuts against the outer edge of the wafer. The guide surface gradually approaches the central axis of the positioning body from top to bottom.

7. The packaging structure according to claim 6, characterized in that, The angle between the guide surface and the central axis of the positioning body is α, which satisfies: 30°≤α≤70°.

8. The packaging structure according to claim 6, characterized in that, The width of one side of the positioning body is D, which satisfies: 0.1mm≤D≤1mm.

9. The packaging structure according to claim 6, characterized in that, The packaging structure further includes an adhesive layer, which is connected to the mounting surface and covers the wafer and the positioning body.

10. The packaging structure according to claim 6, characterized in that, The adhesive material includes at least one of polyethylene terephthalate and acrylate.

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