A method for fabricating a fan-out packaging structure

Abstract

This invention provides a method for fabricating a fan-out package structure, comprising: providing a temporary carrier board; forming a redistribution structure on one side of the temporary carrier board; placing a chip on the side of the redistribution structure opposite to the temporary carrier board, the chip being electrically connected to the redistribution structure; forming an initial molding compound layer on the side of the redistribution structure opposite to the temporary carrier board and on the sidewalls of the redistribution structure and the temporary carrier board, the initial molding compound layer encapsulating the chip; removing the initial molding compound layer from the sidewalls of the redistribution structure and the temporary carrier board, so that the initial molding compound layer forms a molding compound layer, the sidewalls of the molding compound layer being aligned with the sidewalls of the redistribution structure; and after forming the molding compound layer, debonding the temporary carrier board and the redistribution structure. This method for fabricating a fan-out package structure reduces warpage, lowers process costs, and improves yield.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging, and more specifically to a method for preparing a fan-out packaging structure. Background Technology

[0002] In existing wafer-level fan-out packaging processes, the wafer-level fan-out packaging structure is typically fabricated through the following steps: (Refer to...) Figure 1 A temporary bonding film F1 is prepared on the first temporary carrier C1. A wiring layer 10 is prepared on the surface of the temporary bonding film F1. Interconnect pads 11 are prepared on the wiring layer 10. Solder blocks on the conductive pillars 12 of the chip 100 are aligned with the interconnect pads 11. Interconnect solder balls 13 are prepared by high-temperature reflow soldering to complete the conductive connection between the chip and the wiring layer 10. Figure 2 A bottom filler layer 14 is obtained by applying adhesive to the bottom of chip 100; Reference Figure 3 The chip 100 is first encapsulated to obtain the first encapsulation layer E1; Reference Figure 3 The first temporary carrier C1 and the temporary bonding film F1 are removed by debonding. The pre-packaged body is then bonded to the second temporary carrier C2 via the temporary bonding film F2. Afterwards, the chip 100 undergoes a second molding process to obtain the second molding layer E2. (Refer to...) Figure 4 After debonding and removing the second temporary carrier plate C2 and the temporary bonding film F2, external conductive pillars 17 and external solder balls 18 are prepared; the first molding layer E1 and the second molding layer E2 are thinned.

[0003] Due to the limitations of the molding equipment size, the diameter of the first molding compound E1, fabricated on a 300mm diameter temporary substrate C1, is 296mm. However, the subsequent fabrication of external conductive pillars and solder balls requires equipment on a 300mm diameter wafer. Therefore, the size of the molding compound needs to be adjusted to 300mm. In the prior art, after fabricating the first molding compound E1, the first temporary substrate C1 needs to be debonded and removed. The pre-packaged body is then bonded to a 330mm diameter second temporary substrate C2 using a temporary bonding film F2. The pre-packaged body is then placed in a mold for the corresponding molding process to complete the fabrication of the second molding compound E2, thus adjusting the size of the second molding compound E2 to 300mm.

[0004] It should be noted that the size of temporary carrier boards is relatively fixed in the packaging field, meaning there are only a few fixed sizes to choose from. It is difficult to adjust the size of temporary carrier boards at will, especially in mass production, where custom-made temporary carrier board sizes would increase the manufacturing cost of the product.

[0005] Existing technologies adjust the size of the molding layer by secondary molding and matching secondary bonding processes. The process is relatively complicated, and the defect rate and production cost of the product process will increase accordingly. In addition, the secondary molding process requires two high-temperature curing treatments of the molding compound for epoxy resin system, which also increases the warpage of the chip package. Summary of the Invention

[0006] In view of this, the present invention provides a method for preparing a fan-out packaging structure to solve the problems of chip package warpage, low process cost and low yield in the prior art.

[0007] This invention provides a method for fabricating a fan-out package structure, comprising: providing a temporary carrier board; forming a redistribution structure on one side of the temporary carrier board; placing a chip on the side of the redistribution structure opposite to the temporary carrier board, the chip being electrically connected to the redistribution structure; forming an initial molding compound layer on the side of the redistribution structure opposite to the temporary carrier board and on the sidewalls of the redistribution structure and the temporary carrier board, the initial molding compound layer encapsulating the chip; removing the initial molding compound layer from the sidewalls of the redistribution structure and the temporary carrier board, so that the initial molding compound layer forms a molding compound layer, the sidewalls of the molding compound layer being aligned with the sidewalls of the redistribution structure; and after forming the molding compound layer, separating the redistribution structure from the temporary carrier board.

[0008] Optionally, the initial molding layer of the redistribution structure sidewall and the temporary carrier board sidewall is removed by a cutting process, which cuts to the edge area of ​​the initial molding layer, the redistribution structure and a portion of the thickness of the temporary carrier board.

[0009] Optionally, the cutting process cuts to a depth of 20µm-500µm into the temporary carrier plate.

[0010] Optionally, the cutting process includes laser cutting or mechanical cutting.

[0011] Optionally, the diameter of the rewire structure after cutting is 298mm to 302mm.

[0012] Optionally, the initial molding layer extends 0.2µm to 10µm beyond the temporary carrier plate.

[0013] Optionally, in the step of providing a temporary carrier board, a rounded corner is provided at the junction between the bearing surface of the temporary carrier board and the side wall of the temporary carrier board; in the step of forming a redistribution structure on one side of the temporary carrier board, the redistribution structure is located on one side of a portion of the temporary carrier board, and the rounded corner of the temporary carrier board is exposed around the redistribution structure.

[0014] Optionally, the radius corresponding to the rounded corner is 1µm to 10µm.

[0015] Optionally, it further includes: after debonding the temporary carrier and the redistribution structure, a first solder ball is disposed on the side of the redistribution structure opposite to the chip, and the first solder ball is electrically connected to the redistribution structure.

[0016] The technical solution of the present invention can achieve the following beneficial effects:

[0017] In the method for fabricating a fan-out package structure provided by this invention, an initial molding compound is formed on the side of the redistribution structure opposite to the temporary carrier, as well as on the sidewalls of the redistribution structure and the temporary carrier, and the initial molding compound encapsulates the chip. The initial molding compound is then removed from the sidewalls of the redistribution structure and the temporary carrier, forming a molding compound layer with its sidewalls aligned with the sidewalls of the redistribution structure. After forming the molding compound layer, the temporary carrier and the redistribution structure are debonded. This method requires only one molding and one bonding process, simplifying the process flow, improving yield, and reducing costs. Correspondingly, the single molding process reduces the impact of high-temperature processes on the fan-out package structure and reduces warpage. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figures 1 to 4 This is a schematic diagram of the fabrication process of a fan-out packaging structure in the prior art;

[0020] Figure 5 This is a flowchart of the fabrication process of a fan-out packaging structure according to the present invention;

[0021] Figures 6 to 11 This is a schematic diagram of the fabrication process of a fan-out packaging structure according to the present invention. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] This invention provides a method for fabricating a fan-out packaging structure, with reference to... Figure 5 ,include:

[0027] S1: Provides a temporary carrier board;

[0028] S2: A redistribution structure is formed on one side of the temporary carrier board;

[0029] S3: A chip is disposed on the side of the redistribution structure away from the temporary carrier board, and the chip is electrically connected to the redistribution structure;

[0030] S4: An initial molding layer is formed on the side of the redistribution structure opposite to the temporary carrier board, and on the sidewalls of the redistribution structure and the temporary carrier board, the initial molding layer encapsulating the chip;

[0031] S5: Remove the initial molding layer from the sidewalls of the redistribution structure and the temporary carrier board, so that the initial molding layer forms a molding layer, and the sidewalls of the molding layer are aligned with the sidewalls of the redistribution structure.

[0032] S6: After the molding layer is formed, the redistribution structure is separated from the temporary carrier board.

[0033] The method for fabricating the fan-out packaging structure provided in this embodiment requires only one molding and one bonding process, simplifying the process flow, improving the yield, and reducing the cost. Correspondingly, the single molding process reduces the impact of high-temperature processes on the fan-out packaging structure and minimizes its warpage.

[0034] refer to Figure 6 Provide a temporary carrier board of 200.

[0035] The temporary carrier plate 200 includes a glass carrier plate.

[0036] In one embodiment, the temporary carrier plate 200 has a diameter of 300 mm.

[0037] It should be noted that in other embodiments, temporary carrier boards of other fixed sizes can be selected according to the process requirements for rewiring dimensions.

[0038] In this embodiment, during the step of providing the temporary carrier plate 200, a rounded corner is provided at the junction between the bearing surface of the temporary carrier plate and the sidewall of the temporary carrier plate 200. In one embodiment, the radius corresponding to the rounded corner is 1µm to 10µm, for example, 1µm, 2µm, 5µm, 8µm or 10µm.

[0039] In other embodiments, during the step of providing the temporary carrier plate, the junction between the bearing surface of the temporary carrier plate and the sidewall of the temporary carrier plate is at a right angle.

[0040] Continue to refer to Figure 6 A rewiring structure 210 is formed on one side of the temporary carrier board 200.

[0041] Specifically, a rewiring structure 210 is formed on one side of the bearing surface of the temporary carrier board 200.

[0042] Before forming the redistribution structure 210, the method further includes forming a bonding film 201 on the bearing surface of the temporary carrier 200.

[0043] The bonding film includes, but is not limited to, a laser-assisted temporary debonding film. That is, the bonding film serves to provide bonding with a temporary carrier for the fabrication of the redistribution structure and to debond after the completion of related processes based on the redistribution structure. The bonding methods include bonding based on resin systems such as thermoplastic resin, thermosetting resin, and photoresist, and the debonding methods include debonding based on thermal release, chemical release, laser, mechanical release, etc.

[0044] In this embodiment, in the step of forming a rewiring structure 210 on one side of the temporary carrier board 200, the rewiring structure 210 is located on one side of a portion of the temporary carrier board 200, and the rounded corners of the temporary carrier board 200 are exposed around the rewiring structure 210.

[0045] In this embodiment, during the formation of the redistribution structure 210, multiple patterned redistribution layers and multiple dielectric layers need to be formed. The formation of each redistribution layer includes: forming a redistribution seed film; coating a photoresist layer on the redistribution seed film; exposing and developing the photoresist layer to create openings in the photoresist layer, with a portion of the redistribution seed film exposed at the bottom of the openings; then using a deposition process combined with an electroplating or electroless plating process to prepare a metal layer in the redistribution layer within the openings; finally, removing the photoresist layer and the redistribution seed film at the bottom of the photoresist layer, leaving the metal layer and the remaining redistribution seed film to form the redistribution layer. The deposition process is used to prepare the redistribution seed film, and the electroplating or electroless plating process is used to prepare the metal layer in the redistribution layer.

[0046] In this embodiment, because a rounded corner is provided at the junction between the bearing surface of the temporary carrier 200 and the sidewall of the temporary carrier 200, the edge region of the formed redistribution film bends downward toward the temporary carrier 200 relative to the center region of the redistribution film. In the subsequent photoresist coating step, in the right-angle design of the interface, the photoresist under centrifugal force accumulates at the right angle of the interface due to surface tension. Even with centrifugal force, the photoresist accumulated at the right-angle interface will still retract toward the center region of the redistribution film under the reaction force of centrifugal force, resulting in a thicker photoresist film in the vicinity of the right angle. Therefore, in the rounded corner interface design, the surface of the edge region of the photoresist layer will not be higher than the surface of the center region of the photoresist layer, avoiding an excessively thick edge region of the coated photoresist layer. Based on this, the patterning accuracy of the photoresist layer can be improved, and the corresponding patterning accuracy of the formed redistribution layer can be improved.

[0047] In other embodiments, the junction between the bearing surface of the temporary carrier and the sidewall of the temporary carrier is at a right angle, and the diameter of the redistribution structure is the same as the diameter of the temporary carrier.

[0048] In this embodiment, it further includes forming interconnect pads 220 on the surface of the partial redistribution structure 210 facing away from the temporary carrier board 200.

[0049] refer to Figure 7 A chip 230 is disposed on the side of the rewiring structure 210 away from the temporary carrier board 200, and the chip 230 is electrically connected to the rewiring structure 210.

[0050] The chip 230 includes a chip body and conductive posts 231 connected to the chip body; the conductive posts 231 are soldered together with the interconnect pads 220, and a second solder ball 240 is formed between the conductive posts 231 and the interconnect pads 220. The process of soldering the conductive posts 231 to the interconnect pads 220 includes a reflow soldering process.

[0051] In this embodiment, the method further includes forming an underfill layer 250, which is located between the chip 230 and the redistribution structure 210 and encapsulates the interconnect pads 220, conductive pillars 231 and the second solder ball 240.

[0052] refer to Figure 8 An initial molding layer 260 is formed on the side of the redistribution structure 210 away from the temporary carrier board 200, and on the sidewalls of the redistribution structure 210 and the temporary carrier board 200, the initial molding layer 260 encapsulating the chip 230.

[0053] The initial sealing layer 260 also covers the sidewalls of the underfill layer 250.

[0054] In one embodiment, the initial molding layer 260 extends beyond the temporary carrier 200 by a width of 0.2µm to 10µm. This arrangement has the advantage that if the initial molding layer extends beyond the temporary carrier by more than 10µm, it will result in material waste of the molding compound, which is detrimental to industrial cost control. If the initial molding layer extends beyond the temporary carrier by less than 0.2µm, it is highly likely that insufficient precision in the upper mold positioning and pressing will prevent the initial molding layer from completely covering the sidewalls of the chip and redistribution structure, thus failing to provide molding protection for the chip and package interconnects.

[0055] In one embodiment, the initial molding layer 260 has a diameter of 301 mm.

[0056] Will Figure 7 The obtained pre-packaged body is placed in the lower mold of the molding die, and the temporary carrier plate 200 is in contact with the bottom surface of the lower mold. The molding material is placed on the side of the redistribution structure 210 away from the temporary carrier plate 200, as well as on the sidewalls of the redistribution structure 210 and the temporary carrier plate 200. Then, the upper and lower molds of the molding die are used to close the mold, and the inner diameter of the upper mold is larger than the diameter of the temporary carrier plate 200. Then, the molding material is cured. Then, the upper and lower molds are separated.

[0057] Using a feeding mechanism Figure 7The pre-packaged body is placed in the lower mold of the mold. The feeding mechanism has several guide block mechanisms. Adjusting the guide block mechanisms can control the position of the temporary carrier plate 200 in the lower mold, thereby controlling the degree of offset of the temporary carrier plate 200 relative to the lower mold. By adding a pre-packaged body placement recognition module to the molding machine, the placement position of the temporary carrier plate 200 in the mold can be precisely adjusted.

[0058] refer to Figure 9 and Figure 10 , Figure 10 for Figure 9 The enlarged view of region B shows the removal of the initial molding layer 260 from the sidewalls of the redistribution structure 210 and the temporary carrier board 200, resulting in a molding layer 260a. The sidewalls of the molding layer 260a are aligned with the sidewalls of the redistribution structure 210.

[0059] The molding layer 260a is located on the side of the redistribution structure 210 away from the temporary carrier 200 and covers the chip 230 and the underfill layer 250.

[0060] The molding layer 260a covers the sidewall of the chip 230 and the side surface of the chip 230 facing away from the redistribution structure 210.

[0061] The initial molding compound 260, which removes the sidewalls of the redistribution structure 210 and the temporary carrier board 200, is removed using a cutting process. This cutting process extends to the edge areas of the initial molding compound 260, the redistribution structure 210, and a portion of the thickness of the temporary carrier board 200. The cutting process can be either a non-contact laser cutting process or a mechanical contact cutting process.

[0062] Since the cutting process cuts through a portion of the thickness of the temporary carrier plate 200, it makes the subsequent peeling and removal of the temporary carrier plate 200 easier.

[0063] In one embodiment, the cutting process cuts to a depth H1 of 20um-500um into the temporary carrier plate 200, for example, 20um, 50um, 100um, 1500um, 200um, 300um or 500um.

[0064] In one embodiment, the diameter of the redistribution structure 210 after cutting is 298mm to 302mm. The deviation of this size must be controlled within a strictly small range so that the cutting of the redistribution structure 210 does not affect the internal routing of the redistribution structure 210, while satisfying the requirement that the difference between the diameter of the redistribution structure 210 and the temporary carrier board 200 be minimized.

[0065] In one embodiment, after removing the initial molding layer 260 from the sidewalls of the redistribution structure 210 and the temporary carrier board 200, the diameter of the redistribution structure 210 is 298 mm to 302 mm, for example, 299.2 mm, 299.4 mm, 299.6 mm, or 299.8 mm.

[0066] The package with the molding layer 260a is placed on the base of the edge processing machine. Then, a positioning module is used to obtain the edge position of the package, and the center of the package is determined by software calculation. The edges of the package are then processed to reduce its size. In one embodiment, the diameter of the redistribution structure 210 is reduced to 299.4 mm. Positioning the center of the package using a camera ensures high accuracy and facilitates control of offset during edge cutting. The edge processing machine includes a laser cutting machine or a mechanical cutting machine.

[0067] In this embodiment, the control of the edge radius of the temporary carrier 200, the sidewall of the redistribution structure 210 surrounded by the initial molding layer 260 and the sidewall of the temporary carrier 200, and the offset during the edge processing can prevent the edge of the molding layer 260a from lifting after subsequent debonding.

[0068] refer to Figure 11 After forming the molding layer 260a, the temporary carrier board 200 and the rewiring structure 210 are debonded.

[0069] refer to Figure 11 After debonding the temporary carrier board 200 and the redistribution structure 210, a first solder ball 280 is provided on the side of the redistribution structure 210 away from the chip 230, and the first solder ball 280 is electrically connected to the redistribution structure 210.

[0070] In this embodiment, the method further includes: providing an external conductive post on the side of the rewiring structure 210 away from the chip 230, and providing a first solder ball 280 on the side of the external conductive post away from the rewiring structure 210, wherein the first solder ball 280 is electrically connected to the rewiring structure 210 through the external conductive post.

[0071] In this embodiment, the method further includes: thinning the molding layer until the surface of the chip 230 facing away from the redistribution structure 210 is exposed.

[0072] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for fabricating a fan-out packaging structure, characterized in that, include: Provide temporary carrier board; A redistribution structure is formed on one side of the temporary carrier board; A chip is disposed on the side of the redistribution structure opposite to the temporary carrier board, and the chip is electrically connected to the redistribution structure; An initial molding layer is formed on the side of the redistribution structure opposite to the temporary carrier board, and on the sidewalls of the redistribution structure and the temporary carrier board, the initial molding layer encapsulating the chip; the width of the initial molding layer extending beyond the temporary carrier board is 0.2um to 10um. Remove the initial molding layer from the sidewalls of the redistribution structure and the sidewalls of the temporary carrier board, so that the initial molding layer forms a molding layer, and the sidewalls of the molding layer are aligned with the sidewalls of the redistribution structure; The initial molding layer used to remove the sidewalls of the redistribution structure and the temporary carrier board is a cutting process, which cuts to the edge areas of the initial molding layer, the redistribution structure, and a portion of the thickness of the temporary carrier board. After the molding layer is formed, the redistribution structure is separated from the temporary carrier board; The formation of the rewiring structure includes: forming a rewiring structure on one side of the bearing surface of the temporary carrier board; Before forming the redistribution structure, the method further includes: forming a bonding film on the bearing surface of the temporary carrier board; The step of separating the redistribution structure from the temporary carrier after forming the molding layer includes: debonding the temporary carrier and the redistribution structure after forming the molding layer.

2. The method for preparing the fan-out packaging structure according to claim 1, characterized in that, The cutting process cuts to a depth of 20µm-500µm into the temporary carrier plate.

3. The method for preparing the fan-out packaging structure according to claim 1, characterized in that, The cutting process includes laser cutting or mechanical cutting.

4. The method for preparing the fan-out packaging structure according to claim 1, characterized in that, The diameter of the rewire structure after cutting is 298mm to 302mm.

5. The method for preparing the fan-out packaging structure according to claim 1, characterized in that, In the step of providing a temporary carrier plate, a rounded corner is provided at the junction between the bearing surface of the temporary carrier plate and the side wall of the temporary carrier plate; In the step of forming a redistribution structure on one side of the temporary carrier board, the redistribution structure is located on one side of a portion of the temporary carrier board, and the rounded corners of the temporary carrier board are exposed around the redistribution structure.

6. The method for preparing the fan-out packaging structure according to claim 5, characterized in that, The radius corresponding to the rounded corner is 1um to 10um.

7. The method for preparing the fan-out packaging structure according to claim 1, characterized in that, Also includes: After debonding the temporary carrier and the redistribution structure, a first solder ball is placed on the side of the redistribution structure away from the chip, and the first solder ball is electrically connected to the redistribution structure.

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