A bonding structure and fabrication method for increasing the temporary bond strength of molding compound surfaces.

Abstract

This invention relates to a method for fabricating a bonding structure that increases the temporary bonding strength on the surface of a molding compound, comprising: providing a wafer that has undergone molding and thinning; fabricating an adhesion layer on the back side of the wafer; and temporarily bonding the wafer with the adhesion layer to a carrier using a temporary bonding adhesive. The invention also relates to a bonding structure that increases the temporary bonding strength on the surface of a molding compound, comprising: a wafer that has undergone molding and thinning; an adhesion layer covering the back side of the wafer; a bonding adhesive layer covering the adhesion layer; and a carrier disposed above the bonding adhesive layer. This method and structure, by spin-coating an organic material onto the surface of the thinned molding compound, selectively performing photolithography, and then performing a temporary bonding process, can effectively improve the adhesion between the carrier and the molding compound, supporting subsequent redistribution fabrication, solder ball plating, or TSV back-side exposure processes.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and in particular to a bonding structure and manufacturing method for increasing the temporary bonding strength on the surface of molding compound. Background Technology

[0002] With the development of technology, electronic products are becoming increasingly miniaturized and multifunctional. Electronic systems are being made smaller, more integrated, and more and more powerful. To meet these demands, the semiconductor industry needs to thin device wafers to 100 micrometers or less. The fragility of ultra-thin wafers, along with their susceptibility to warping and undulation, poses significant challenges to wafer thinning and thin-chip processing.

[0003] For RDL-first Fanout or CoWoS technologies, after molding and thinning, back-side wafer-level processes are performed, such as RDL, solder ball plating, or TSV back-side exposure. Because the epoxy molding compound (EMC) is thinned to a very thin layer or due to warpage, it's difficult to perform these processes directly, requiring temporary bonding to assist in subsequent processes. However, due to the poor adhesion between the EMC material and the temporary bonding adhesive, wafer warpage or stress from high temperatures can cause delamination of the temporary bonding. Summary of the Invention

[0004] The objective of this invention is to provide a bonding structure and manufacturing method that increases the temporary bonding strength of the molding compound surface. By spin-coating an organic material onto the surface of the thinned molding compound and selectively performing photolithography, followed by a temporary bonding process, the adhesion between the substrate and the molding compound can be effectively improved to support subsequent redistribution fabrication, solder ball plating, or TSV back-side exposure processes.

[0005] In a first aspect, addressing the problems existing in the prior art, the present invention provides a method for fabricating a bonding structure that increases the temporary bonding strength of a molding compound surface, comprising:

[0006] Provides wafers that have undergone complete molding and thinning.

[0007] An adhesion layer is fabricated on the back side of the wafer; and

[0008] Temporary bonding adhesive is used to temporarily bond the wafer with the adhesion layer to the substrate.

[0009] In a preferred embodiment of the invention, the method further includes: performing a photolithography process on the adhesion layer to remove the adhesion layer above the chip in the wafer.

[0010] In another preferred embodiment of the invention, the adhesion layer is formed by spin-coating an organic material onto the back side of the wafer.

[0011] In another preferred embodiment of the present invention, the material of the adhesive layer is specified as a photosensitive resin.

[0012] In another preferred embodiment of the invention, a temporary bonding adhesive is applied over the adhesive layer to form a bonding adhesive layer;

[0013] The wafer with the bonding adhesive layer is bonded to the carrier to obtain a temporary wafer bonding pair.

[0014] In another preferred embodiment of the invention, a temporary bonding adhesive is coated on the surface of the substrate to form a bonding adhesive layer;

[0015] A temporary wafer bonding pair is obtained by bonding the bonding adhesive layer on the surface of the carrier to the adhesive layer on the back side of the wafer.

[0016] In a second aspect of the invention, addressing the problems existing in the prior art, the present invention provides a bonding structure for increasing the temporary bonding strength of a molding compound surface, comprising:

[0017] Wafers that have undergone plastic encapsulation and thinning;

[0018] An adhesion layer covering the back side of the wafer;

[0019] A bonding adhesive layer, the bonding adhesive layer covering the adhesive layer above it; and

[0020] A carrier sheet is disposed above the bonding adhesive layer.

[0021] In a preferred embodiment of the present invention, the wafer that has undergone plastic encapsulation and thinning includes:

[0022] chip;

[0023] Metal pads, the metal pads being located on the front side of the chip;

[0024] A molding compound layer that encapsulates the chip;

[0025] A passivation layer covers the front side of the chip and the molding compound, encapsulating the metal pads.

[0026] In another preferred embodiment of the invention, the adhesive layer covers the back side of the chip and the molding compound.

[0027] In another preferred embodiment of the invention, the adhesive layer covers the back side of the encapsulation layer.

[0028] The present invention has at least the following beneficial effects: The present invention discloses a bonding structure and manufacturing method for increasing the temporary bonding strength of the molding compound surface. By spin-coating an organic material onto the surface of the thinned molding compound and selectively performing photolithography, followed by a temporary bonding process, the adhesion between the substrate and the molding compound can be effectively improved to support subsequent redistribution fabrication, solder ball plating, or TSV back-side exposure processes. The method is simple, low-cost, and effective. Attached Figure Description

[0029] To further illustrate the above and other advantages and features of the various embodiments of the present invention, a more specific description of the embodiments of the invention will be presented with reference to the accompanying drawings. It is to be understood that these drawings depict only typical embodiments of the invention and are therefore not intended to limit its scope. In the drawings, identical or corresponding parts will be indicated by identical or similar reference numerals for clarity.

[0030] Figure 1 A schematic diagram of a bonding structure for increasing the temporary bonding strength of a molding compound surface is shown according to an embodiment of the present invention.

[0031] Figures 2A to 2C A cross-sectional schematic diagram of the fabrication process of a bonding structure for increasing the temporary bonding strength of a molding compound surface, according to an embodiment of the present invention, is shown. Detailed Implementation

[0032] It should be noted that the components in the accompanying drawings may be shown exaggerated for illustrative purposes and may not be to scale.

[0033] In this invention, the various embodiments are merely intended to illustrate the solutions of the invention and should not be construed as limiting.

[0034] In this invention, unless otherwise specified, the quantifiers “a” and “one” do not exclude scenarios involving multiple elements.

[0035] It should also be noted that, in the embodiments of the present invention, only a portion of the parts or components may be shown for clarity and simplicity. However, those skilled in the art will understand that, under the teachings of the present invention, the required parts or components can be added as needed for specific scenarios.

[0036] It should also be noted that within the scope of this invention, the terms "same", "equal", and "equal to" do not mean that the two values ​​are absolutely equal, but allow for a certain reasonable error. In other words, the terms also cover "substantially the same", "substantially equal", and "substantially equal to".

[0037] It should also be noted that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "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 explicitly or implicitly suggest 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" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0038] Furthermore, the embodiments of the present invention describe the process steps in a specific order. However, this is only for the convenience of distinguishing each step, and is not a limitation on the order of each step. In different embodiments of the present invention, the order of each step can be adjusted according to the process.

[0039] Figure 1 A schematic diagram of a bonding structure for increasing the temporary bonding strength of a molding compound surface is shown according to an embodiment of the present invention.

[0040] like Figure 1 As shown, the temporary bonding structure with an adhesive layer includes a wafer 100 that has undergone wafer-level molding or molding thinning, an adhesive layer 200, a bonding adhesive layer 300, and a carrier 400.

[0041] The wafer 100 after molding and thinning includes a first chip 101, a second chip 102, metal pads 103, a passivation layer 104, and a molding layer 105. The molding layer 105 encapsulates the first chip 101 and the second chip 102. The metal pads 103 are located on the front side of the first chip 101 and the second chip 102. The passivation layer covers the front side of the first chip 101, the second chip 102, and the molding layer, and encapsulates the metal pads 103. The first chip 101 and the second chip 102 can be logic chips such as CPUs, DSPs, GPUs, and FPGAs, or memory chips such as DRAMs and Flash, or other types of chips such as SOCs or sensors (such as MEMS sensors). The first chip 101 and the second chip 102 can be the same type of chip or different types of chips. In one embodiment of the present invention, the material of the molding layer is epoxy molding compound (EMC).

[0042] When the chip does not require heat dissipation, the adhesion layer 200 covers the back side of the first chip 101, the second chip 102, and the molding compound layer 105; that is, the adhesion layer 200 covers the back side of the wafer 100 after wafer-level molding or molding thinning. In one embodiment of the present invention, the material of the adhesion layer is a highly viscous organic material, such as polyimide, bis(phenylcyclobutene) resin, phenylbenzodioxazole resin, etc. Due to their inherent viscosity, organic materials have good adhesion to EMC materials or substrate materials such as glass / silicon, which can effectively improve the adhesion between the substrate and the EMC to support subsequent processes.

[0043] When the chip requires heat dissipation, the adhesive layer 200 covers the back side of the molding compound 105. When the chip requires heat dissipation, the adhesive layer 200 is photolithographically removed from the first chip 101 and the second chip 102. In one embodiment of the present invention, the material of the adhesive layer is a photosensitive resin.

[0044] The bonding adhesive layer 300 covers the adhesive layer 200. In one embodiment of the present invention, the bonding adhesive layer is made of thermoplastic or thermosetting organic material, or it can be an inorganic material containing components such as Cu, Ni, Cr, and Co. The bonding adhesive layer can be removed by heating, mechanical, chemical, laser, freezing, or other methods. During the removal of the bonding adhesive layer, the adhesive layer will not decompose due to the removal process.

[0045] The carrier 400 is disposed above the bonding adhesive layer 300. In one embodiment of the present invention, the carrier is generally a single-crystal silicon wafer, but other materials may also be selected, such as glass carriers, organic substrates, metal substrates, ceramic substrates, substrates composed of organic and metal substrates, or other similar materials. Those skilled in the art should understand that any flat surface with a specific strength can be used as the carrier of the present invention.

[0046] Figures 2A to 2C A cross-sectional schematic diagram of the fabrication process of a bonding structure for increasing the temporary bonding strength of a molding compound surface, according to an embodiment of the present invention, is shown.

[0047] In step 1, as Figure 2A As shown, a wafer 100 with completed molding and thinning is provided. The wafer 100 includes a first chip 101, a second chip 102, metal pads 103, a passivation layer 104, and a molding layer 105. The molding layer 105 encapsulates the first chip 101 and the second chip 102. The metal pads are located on the front sides of the first chip 101 and the second chip 102. The passivation layer covers the front sides of the first chip 101, the second chip 102, and the molding layer, and encapsulates the metal pads 103.

[0048] In step 2, as Figure 2BAs shown, an adhesion layer 200 is formed on the back side of wafer 100. The adhesion layer 200 is formed by spin-coating an organic material onto the back side of wafer 100. In one embodiment of the present invention, when the chip requires heat dissipation, the material of the adhesion layer is a photosensitive resin capable of photolithography.

[0049] Optionally, in step 3, such as Figure 2B As shown, a photolithography process is performed on the adhesion layer 200 to remove the adhesion layer on top of the chip. In one embodiment of the present invention, photolithography is performed on the adhesion layer 200 to remove the adhesion layer covering the first chip 101 and the second chip 102, exposing the first chip 101 and the second chip 102.

[0050] In step 4, as Figure 2C As shown, a wafer 100 with an adhesive layer 200 is temporarily bonded to a carrier 400 using temporary bonding adhesive. A first method for temporarily bonding a wafer 100 with an adhesive layer 200 to a carrier 400 includes: coating a temporary bonding adhesive layer 300 over the adhesive layer 200; and bonding the wafer 100 with the bonding adhesive layer 300 to the carrier 400 to obtain a temporary wafer bond pair. A second method for temporarily bonding a wafer 100 with an adhesive layer 200 to a carrier 400 includes: coating a temporary bonding adhesive layer 300 on the surface of the carrier 400; and bonding the bonding adhesive layer 300 on the surface of the carrier 400 to the adhesive layer 200 on the back side of the wafer 100 to obtain a temporary wafer bond pair.

[0051] It can be used to perform subsequent rewiring, solder ball plating, or TSV back-end exposure processes on the temporarily bonded wafer.

[0052] The present invention has at least the following beneficial effects: The present invention discloses a bonding structure and manufacturing method for increasing the temporary bonding strength of the molding compound surface. By spin-coating an organic material onto the surface of the thinned molding compound and selectively performing photolithography, followed by a temporary bonding process, the adhesion between the substrate and the molding compound can be effectively improved to support subsequent redistribution fabrication, solder ball plating, or TSV back-side exposure processes. The method is simple, low-cost, and effective.

[0053] While some embodiments of the present invention have been described in this application, those skilled in the art will understand that these embodiments are merely illustrative. Numerous variations, alternatives, and improvements will arise in those skilled in the art under the teachings of this invention without departing from its scope. The appended claims are intended to define the scope of the invention and thereby cover methods and structures within the scope of the claims themselves and their equivalents.

Claims

1. A method for fabricating a bonding structure to increase the temporary bond strength on the surface of a molding compound, comprising: Provides wafers that have undergone complete molding and thinning. An adhesion layer is created on the back side of the wafer; The material of the adhesive layer is photosensitive resin; The adhesion layer is removed by photolithography to remove the adhesion layer above the chip in the wafer; as well as Temporary bonding adhesive is used to temporarily bond the wafer with the adhesion layer to the substrate.

2. The method for fabricating a bonding structure to increase the temporary bonding strength of the molding compound surface as described in claim 1, characterized in that, The adhesion layer is formed by spin-coating an organic material onto the back side of the wafer.

3. The method for fabricating a bonding structure to increase the temporary bonding strength of the molding compound surface as described in claim 1, characterized in that, A temporary bonding adhesive is applied over the adhesive layer to form a bonding adhesive layer; The wafer with the bonding adhesive layer is bonded to the carrier to obtain a temporary wafer bonding pair.

4. The method for fabricating a bonding structure to increase the temporary bonding strength of the molding compound surface as described in claim 1, characterized in that, A temporary bonding adhesive is coated on the surface of the substrate to form a bonding adhesive layer; A temporary wafer bonding pair is obtained by bonding the bonding adhesive layer on the surface of the carrier to the adhesive layer on the back side of the wafer.

5. A bonding structure for increasing the temporary bond strength of a molding compound surface, formed by the method for fabricating a bonding structure for increasing the temporary bond strength of a molding compound surface according to any one of claims 1 to 4, comprises: Wafers that have undergone plastic encapsulation and thinning; An adhesion layer covering the back side of the wafer; A bonding adhesive layer, which covers the adhesive layer above the adhesive layer; as well as A carrier sheet is disposed above the bonding adhesive layer.

6. The bonding structure for increasing the temporary bonding strength of the molding compound surface as described in claim 5, characterized in that, The wafer that has undergone molding and thinning includes: chip; Metal pads, the metal pads being located on the front side of the chip; A molding compound layer that encapsulates the chip; A passivation layer covers the front side of the chip and the molding compound, encapsulating the metal pads.

7. The bonding structure for increasing the temporary bonding strength of the molding compound surface as described in claim 6, characterized in that, The adhesive layer covers the back of the encapsulation layer.

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