Patent Application
20230282531
The present invention belongs to the field of semiconductor packaging technologies, and particularly relates to a wafer-level fan-out structure and a manufacturing method thereof.
The fan-out wafer-level package (FOWLP) technology is an improvement of the wafer-level package (WLP) technology and can provide more external connections for a single chip. In the FOWLP technology, chips are embedded into a plastic packaging material, then a high-density redistribution layer (RDL) is built on the surface of a wafer, and solder balls are applied to form a reconstituted wafer.
In the process of manufacturing the reconstituted wafer, the chips are coated and packaged with a cladding material, and the fan-out ratio (ratio of package size/chip size) may significantly affect the warpage of the reconstituted wafer or a large panel. An excessively high or low fan-out ratio may cause excessive warpage of the reconstituted wafer, making production impossible.
Currently, the use of a cladding material with a relatively low Young’s modulus can reduce the warpage of chips in a cladding and packaging process and the warpage of a finished product, and reduce the influence of the fan-out ratio on the warpage. However, the low Young’s modulus of the cladding material may lead to insufficient strength of a package.
In view of this, it is necessary to provide a novel wafer-level fan-out structure to solve the aforementioned problem of insufficient strength of the package due to the low Young’s modulus of the cladding material.
An object of the present invention is to provide a wafer-level fan-out structure and a manufacturing method thereof, in which the warpage of a reconstituted wafer in the FOWLP technology is avoided while the strength of the wafer-level fan-out structure is enhanced by embedding a sheet-like structure in a plastic packaging layer.
To solve the above problem, the technical solution of the present invention provides a wafer-level fan-out structure. The wafer-level fan-out structure includes a plurality of chips, a sheet-like structure and a plastic packaging layer. The plastic packaging layer covers the plurality of chips and the sheet-like structure. The sheet-like structure includes a first region and a second region. The first region includes a plurality of spaced apertures, and each aperture is adjacent to the second region. The plurality of chips and the plurality of apertures are in one-to-one correspondence, and each chip is located in the corresponding aperture. The Young’s modulus of the plastic packaging layer is lower than that of the sheet-like structure, and the ratio of the area of the first region to the area of the second region is (0.5-2): 1.
As an optional technical solution, each chip includes an active surface and a connection terminal, and the connection terminal is located on the active surface. The wafer-level fan-out structure further includes: a redistribution layer disposed on the active surface side and electrically connected to the connection terminal; and an interconnection structure which is disposed on a side surface of the redistribution layer away from the connection terminal and is electrically connected to the redistribution layer.
As an optional technical solution, the plastic packaging layer covers the chip and the sheet-like structure on the active surface side, the connection terminal is exposed from a surface of the plastic packaging layer away from the active surface, and the redistribution layer is disposed on a surface of the plastic packaging layer.
As an optional technical solution, the chip includes a back surface facing away from the active surface. The plastic packaging layer covers the chip and the sheet-like structure on a back surface side, wherein the active surface is not covered with the plastic packaging layer, and the redistribution layer is disposed on the active surface and the surface of the sheet-like structure not covered with the plastic packaging layer.
As an optional technical solution, the sheet-like structure further includes a metal post; the metal post is embedded into the second region and includes a connection end surface; the connection end surface and the connection terminal are located on the same side; and the connection end surface and the redistribution layer are electrically connected to each other.
As an optional technical solution, the ratio of the thickness of the sheet-like structure, the film thickness of the plastic packaging layer and the thickness of the chip is (0.5-2):(1-2): 1.
As an optional technical solution, the sheet-like structure is made of pure metal, alloy, organic resin or a combination thereof.
As an optional technical solution, the alloy is hard alloy or stainless steel.
As an optional technical solution, the organic resin is epoxy resin, phenolic resin, amino resin or unsaturated polyester resin.
As an optional technical solution, the sheet-like structure further includes a plurality of cutting lines, the plurality of cutting lines are located in the second region and surround the plurality of apertures, and a plurality of single packages are obtained by cutting the wafer-level fan-out structure along the plurality of cutting lines.
As an optional technical solution, in each single package, the ratio of the area of the chip to the area of the plastic packaging layer surrounding the chip is 1:(1-15); and the ratio of the area of the chip to the area of the sheet-like structure surrounding the chip is 1:(1-15), wherein the area of the sheet-like structure surrounding the chip is less than or equal to the area of the plastic packaging layer.
The present invention further provides a manufacturing method of a wafer-level fan-out structure, including:
As an optional technical solution, the manufacturing method further includes: forming a redistribution layer on the active surface, the redistribution layer and the connection terminal being electrically connected to each other; and manufacturing an interconnection structure on a portion of the redistribution layer away from the active surface.
As an optional technical solution, the manufacturing method further includes: making the connection terminal protrude away from the carrier plate, a back surface of the chip being temporarily bonded to the temporary bonding layer; coating an active surface side with a plastic packaging material, the plastic packaging material covering the sheet-like structure and the chip; stripping the temporary bonding layer and the carrier plate; thinning the plastic packaging layer until the connection terminal is exposed from a surface of the plastic packaging layer away from the active surface; and forming the redistribution layer on a surface of the thinned plastic packaging layer.
As an optional technical solution, the manufacturing method further includes: temporarily bonding the connection terminal to the temporary bonding layer, a back surface of the chip being away from the carrier plate; coating a back surface side with a plastic packaging material, the plastic packaging material covering the sheet-like structure and the chip to constitute the plastic packaging layer; stripping the temporary bonding layer and the carrier plate; and forming the redistribution layer on a surface of the sheet-like structure not covered with the plastic packaging layer and on the active surface.
Compared with the prior art, the present invention provides the wafer-level fan-out structure and the manufacturing method thereof, in which the Young’s modulus of the plastic packaging layer is controlled to be low so as to be able to reduce warpage caused by the plastic packaging layer during reconstitution of the wafer, and the sheet-like structure with a high Young’s modulus is embedded into the plastic packaging layer, so that the package strength can be improved on the one hand, and on the other hand, by use of rigidity of the sheet-like structure, the warpage caused by the plastic packaging layer during reconstitution of the wafer can also be reduced, thereby further reducing the warpage of each single package in the fan-out structure. Selecting the area ratio of the apertures in the sheet-like structure to the sheet-like structure on the one hand effectively reduces the warpage of the wafer-level fan-out structure, and on the other hand, provides enough support to improve the package strength of the wafer-level fan-out structure.
The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, which are not intended to limit the present invention.
For clearer descriptions of the technical solutions in the embodiments of the present invention or in the prior art, the following briefly introduces the accompanying drawings required for describing the specific embodiments or the prior art. Apparently, the accompanying drawings in the following description show some embodiments of the present invention, and a person of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative efforts.
In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.
In the description of the present invention, it should be noted that orientation or positional relationships indicated by the terms such as “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inner”, and “outer” are orientation or positional relationships shown on the basis of the drawings, only for the purposes of facilitating description of the present invention and simplifying the description, but do not indicate or imply that specified apparatuses or elements must have specific directions, or be constructed or operated in the specific directions, and should not be understood as limitations to the present invention.
One of objects of the present invention is to provide a wafer-level fan-out structure in which a sheet-like structure and a chip are embedded into a plastic packaging layer, and the chip is limited by an aperture of the sheet-like structure. The sheet-like structure with a higher Young’s modulus may be configured to enhance the package strength of the wafer-level fan-out structure while a plastic packaging material with a lower Young’s modulus is configured to reduce warpage of the fan-out structure. In addition, a manufacturing process of the wafer-level fan-out structure belongs to the FOWLP technology, in which the presence of the sheet-like structure helps to reduce warpage of a reconstituted wafer and warpage of the wafer-level fan-out structure in the process of manufacturing the reconstituted wafer by plastic-packaging a plurality of chips and the wafer-level sheet-like structure on a carrier plate.
As shown in
In the wafer-level fan-out structure according to this embodiment, the Young’s modulus of the plastic packaging layer is controlled to be low so as to be able to reduce warpage caused by the plastic packaging layer during reconstitution of a wafer. The sheet-like structure with a high Young’s modulus is embedded into the plastic packaging layer, so that the package strength can be improved on the one hand, and on the other hand, by use of rigidity of the sheet-like structure, the warpage caused by the plastic packaging layer during reconstitution of the wafer can also be reduced, thereby further reducing the warpage of each single package in the fan-out structure. Furthermore, selecting the area ratio of the apertures in the sheet-like structure to the sheet-like structure on the one hand effectively reduces the warpage of the wafer-level fan-out structure, and on the other hand, provides enough support to improve the package strength of the wafer-level fan-out structure.
Continuing to refer to
An interconnection structure 5 is disposed on a side of the redistribution layer 4 away from the active surface and is electrically connected to the conductive layer 4a. The interconnection structure 5 may be a metal bump, a metal post, a solder ball, or a metal post with a tin cap.
As shown in
The apertures 2a shown in
In this embodiment, the plurality of apertures 2a constitute the first region, and the sum of the areas of the plurality of apertures 2a equals the area of the first region, while the area of the second region 2b refers to the area of regions other than the apertures 2a in the sheet-like structure 2.
In addition, the sheet-like structure 2 further includes a plurality of cutting lines 2c disposed in the second region 2b. The cutting lines 2c may be groove structures formed on either of two opposite surfaces of the sheet-like structure 2 or through grooves running through the two opposite surfaces of the sheet-like structure 2. The plurality of cutting lines 2c are disposed around the plurality of apertures 2a, and a plurality of independent single packages (as shown in
Moreover, the plurality of cutting lines 2c may be configured for stress relief during curing of a plastic packaging material of the plastic packaging layer 3.
In each single package, the ratio of the area of the chip 1 to the area of the plastic packaging layer 3 surrounding the chip 1 is 1:(1-15); the ratio of the area of the chip 1 to the area of the sheet-like structure 2 surrounding the chip 1 is 1:(1-15); and the area of the sheet-like structure 2 surrounding the chip 1 is less than or equal to the area of the plastic packaging layer 3.
As shown in
As shown in
In some embodiments of the present invention, the sheet-like structure 2 is made of pure metal, alloy, organic resin or a combination thereof. The pure metal means that a material contains more than 95% of certain metal element, and the pure metal is preferably Cu.
In some embodiments, the alloy is for example hard alloy or stainless steel.
In some embodiments, the organic resin is thermosetting resin such as epoxy resin, phenolic resin, amino resin or unsaturated polyester resin.
In some embodiments, the sheet-like structure 2 may also be made from such inorganic materials as silicon and its oxides, nitride flakes and ceramic flakes. If the sheet-like structure 2 is made from an inorganic insulating material such as silicon oxide, silicon carbide and silicon nitride, it may be directly formed in the manufacturing process of the fan-out structure by thin film preparation processes such as physical vapor deposition and chemical vapor deposition, and provided with apertures by means of a patterning process (photoetching process).
It should be noted that the sheet-like structure 2, the plastic packaging layer 3 and the chip 1 may be of different thickness ratios and area ratios according to different materials selected.
Based on the different materials of the sheet-like structure 2, in case of the same thickness and area, different materials such as epoxy resin, copper sheet, stainless steel and alloy and their corresponding single packages are improved in three-point bending strength compared with single packages containing only the same plastic packaging material.
Specifically, the three-point bending strength of the single package added with the epoxy resin sheet-like structure is 1.2 to 1.5 times higher than that of the single package containing only the same plastic packaging material; the three-point bending strength of the single package added with the copper sheet-like structure is 2 to 2.8 times higher than that of the single package containing only the same plastic packaging material; the three-point bending strength of the single package added with the stainless steel sheet-like structure is 4 to 5 times higher than that of the single package containing only the same plastic packaging material; and the three-point bending strength of the single package added with the alloy sheet-like structure is 5 to 6 times higher than that of the single package containing only the same plastic packaging material. When being made from a material with a high Young’s modulus, the sheet-like structure 2 has significant beneficial effects on improving the package strength of the single package.
The process of manufacturing the wafer-level fan-out structure in
As shown in
A sheet-like structure 2 is attached to a surface of the temporary bonding layer 20, and a chip 1 is mounted in each aperture 2a. A back surface 1b of the chip 1 is temporarily bonded to the temporary bonding layer 20. A connection terminal 1a on an active surface of the chip 1 protrudes away from the temporary bonding layer 20. Preferably, the connection terminal 1a protrudes from the surface of the sheet-like structure 2 away from the carrier plate 10.
Since the Young’s modulus of the sheet-like structure 2 is higher than that of the plastic packaging material forming the plastic packaging layer 3, the sheet-like structure has certain rigidity and then can provide stable support to avoid warpage in manufacture of the reconstituted wafer. In addition, the plastic packaging layer 3 is made from a low-modulus plastic packaging material, for example, a thermoplastic material. The low-modulus plastic packaging material produces lower less shrinkage stress during curing and thus the reconstituted wafer tends to warp, making it easier to avoid warpage. The combination of the sheet-like structure 2 and the low-modulus plastic packaging material reduces the warpage without adversely affecting the package strength and the package stability of the wafer-level fan-out structure.
As shown in
After the plastic packaging layer 3 covers the sheet-like structure 2 and the chip 1, the carrier plate 10 and the temporary bonding layer 20 are stripped from a back surface 1b side of the chip 1.
By means of the thinning process, the top surface of the plastic packaging layer 3 is thinned until the connection terminal 1a on the active surface of the chip 1 is exposed from the surface of the plastic packaging layer 3 away from the active surface.
A redistribution process is conducted to form a redistribution layer 4 on the surface of the thinned plastic packaging layer 3. The redistribution layer 4 includes conductive layers 4a and dielectric layers 4b, which are alternately arranged, and the multiple conductive layers 4a are electrically connected through dielectric through holes formed in the dielectric layers 4b. The dielectric through hole refers to a through hole running through the dielectric layer 4b in the packaging process, and the through hole is filled with a conductive material.
An interconnection structure 5 is formed on the surface of the redistribution layer 4 and electrically connected to the conductive layer 4a. The interconnection structure 5 may be a metal bump, a metal post, a solder ball, or a metal post with a tin cap.
Finally, a plurality of independent single packages are obtained by cutting through a dicing process.
As shown in
As shown in
Specifically, the active surface side is coated with the plastic packaging material to form the plastic packaging layer 3 plastic-packaging the sheet-like structure 2 and the chip 1, and the pad bump 7 is located in the plastic packaging layer 3.
Further, the plastic packaging layer 3 is thinned until the pad bump 7 and the connection terminal 1a on the active surface of the chip 1 are exposed together from the side of the plastic packaging layer 3 away from the active surface.
The conductive layer 4a in the redistribution layer 4 subsequently manufactured on the thinned plastic packaging layer 3 is electrically connected to the pad bump 7, which in turn allows the conductor post 6 in the sheet-like structure 2 to be electrically connected to the chip 1 and the conductive layer 4a in the redistribution layer 4 by the pad bump 7, providing more signal output terminals for signal output of the chip 1.
When the sheet-like structure 2 is made of a dielectric resin material, the conductor post 6 is for example a metal post made of a metal material, such as a cooper pillar, an aluminum pillar, a silver pillar and a palladium pillar, and may also be a post made from other conductive materials, which is not limited in the embodiment of the present invention.
As shown in
In the wafer-level fan-out structure provided in
As shown in
Optionally, the conductor post 6 is for example a structure that runs through the sheet-like structure 2. After the plastic packaging layer 3 on the back surface 1b side of the chip 1 is thinned, another connection end surface 6b opposite to the connection end surface 6a may be exposed from the surface of the thinned plastic packaging layer 3 away from the back surface 1b.
In conjunction with the manufacturing processes of the wafer-level fan-out structures shown in
As shown in
Optionally, the manufacturing method further includes: forming a redistribution layer on the active surface, the redistribution layer and the connection terminal being electrically connected to each other; and manufacturing an interconnection structure on a portion of the redistribution layer away from the active surface.
Optionally, the manufacturing method further includes: obtaining a plurality of independent single packages by cutting the wafer-level fan-out structure along cutting lines of the sheet-like structure.
Optionally, the manufacturing method further includes: making the connection terminal protrude in a direction away from the carrier plate, a back surface of the chip being temporarily bonded to the temporary bonding layer; coating the active surface side with a plastic packaging material, the plastic packaging material covering the sheet-like structure and the chip; stripping the temporary bonding layer and the carrier plate; thinning the plastic packaging layer until the connection terminal is exposed from the surface of the plastic packaging layer away from the active surface; and forming the redistribution layer on a surface of the thinned plastic packaging layer.
Optionally, the manufacturing method further includes: temporarily bonding the connection terminal to the temporary bonding layer, a back surface of the chip being away from the carrier plate; coating the back surface side with a plastic packaging material, the plastic packaging material covering the sheet-like structure and the chip to constitute a plastic packaging layer; stripping the temporary bonding layer and the carrier plate; and forming the redistribution layer on the surface of the sheet-like structure not covered with the plastic packaging layer and on the active surface.
The above manufacturing methods are all realized by the wafer-level process, and belong to the FOWLP technology. In the manufacturing methods, the sheet-like structure is a wafer-level sheet-like structure and includes the plurality of apertures; the carrier plate and the wafer-level sheet-like structure are adapted to each other; the plurality of chips are provided, and each chip is mounted into the corresponding aperture; and the plastic packaging material is coated and cured for plastic-packaging the chips and the sheet-like structure to form the reconstituted wafer including a plurality of single packages.
In summary, the present invention provides the wafer-level fan-out structure and the manufacturing method thereof, in which the Young’s modulus of the plastic packaging layer is controlled to be low so as to be able to reduce warpage caused by the plastic packaging layer during reconstitution of the wafer; and the sheet-like structure with a high Young’s modulus is embedded into the plastic packaging layer, so that the package strength can be improved on the one hand, and on the other hand, by use of rigidity of the sheet-like structure, the warpage caused by the plastic packaging layer during reconstitution of the wafer can also be reduced, further reducing the warpage of each single package in the fan-out structure. Furthermore, selecting the area ratio of the apertures in the sheet-like structure to the sheet-like structure on the one hand effectively reduces the warpage of the wafer-level fan-out structure, and on the other hand, provides enough support to improve the package strength of the wafer-level fan-out structure.
The present invention has been described by the above-mentioned related embodiments which, however, are only examples for implementing the present invention. In addition, the technical features involved in the different embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. It is necessary to point out that the present invention may have many other embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present invention without departing from the spirit and essence of the present invention, and these corresponding changes and modifications should all fall within the scope of protection of the appended claims of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202210198835.7 | Mar 2022 | CN | national |
