Preparation method and structure of rewiring layer

Abstract

The present invention provides a preparation method and structure of a rewiring layer, the method comprising: forming a diffusion barrier layer and a metal seed layer on a supporting substrate; forming a photoresist layer with a filling window on the metal seed layer; sequentially forming a metal wire layer and a buffer layer on the metal seed layer; forming a laminated structure of at least two protective layers on the buffer layer, and performing a cleaning process between forming two adjacent protective layers; removing the photoresist layer, the metal seed layer and the diffusion barrier layer; and electrically leading out the protective layer. By combining an electroplating process with a cleaning process to form a laminated structure, there is no through-hole between the laminated structure and the buffer layer, which effectively improves the continuity of the protective layer structure, thereby improving the adhesion between the buffer layer and the laminated structure, improving the stability of the rewiring layer, and in the subsequent WB process, it is not easy for the buffer layer and the laminated structure to peel off, thereby effectively improving the product yield of the rewiring layer.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer-level packaging in integrated circuits, and in particular to a preparation method and structure of a rewiring layer. Background Art

[0002] As integrated circuits become more powerful, with higher performance and integration, and as new integrated circuits emerge, packaging technology plays an increasingly important role in integrated circuit products, accounting for an increasing proportion of the value of the entire electronic system. At the same time, as the feature size of integrated circuits reaches the nanometer level, transistors develop towards higher density and higher clock frequency, and packaging also develops towards higher density.

[0003] Wafer-level packaging (WLP) technology has become an important packaging method for electronic devices such as high-demand mobile / wireless networks due to its advantages of miniaturization, low cost, high integration, better performance and higher energy efficiency. It is one of the most promising packaging technologies. WLP technology uses the entire wafer as a packaging and testing object, and then cuts it into a single finished chip. This packaging process is different from the traditional chip packaging process. The size of the packaged chip of WLP technology is about 20% smaller than that of the packaged chip of the traditional packaging process. Therefore, the volume of the wafer-level packaged chip is almost the same as the size of the bare chip, which can greatly reduce the size of the packaged chip.

[0004] In the existing WLP process, the manufacture of the redistribution layer (RDL) is the more complex and expensive part of the entire WLP process. The RDL generally includes a dielectric layer and a metal layer, which can re-layout the soldering area positions of the chip's pads so that the new soldering areas meet the minimum spacing requirements for the solder balls and are arranged in an array.

[0005] In the existing RDL process, a metal line layer, a buffer layer and a protective layer are sequentially formed as the metal layer in the RDL. After the metal layer is formed, pores extending into the buffer layer are formed on the surface of the protective layer, resulting in discontinuity of the protective layer structure. Fig.15 As shown in the SEM image, black spots and / or pits appear. The pores reduce the adhesion between the buffer layer and the protective layer and the hardness of the protective layer, thereby increasing the risk of peeling of the protective layer during the subsequent wire bonding process and reducing the stability of the RDL. Summary of the invention

[0006] In view of the shortcomings of the prior art mentioned above, the object of the present invention is to provide a method for preparing a rewiring layer and a structure thereof, so as to solve the problem in the prior art that when preparing a metal layer composed of a metal wire layer, a buffer layer and a protective layer as a rewiring layer, pores extending into the buffer layer will be formed on the surface of the protective layer, and the pores will reduce the adhesion between the buffer layer and the protective layer and the hardness of the protective layer, thereby increasing the risk of peeling of the protective layer during the subsequent wiring process.

[0007] To achieve the above object and other related objects, the present invention provides a method for preparing a rewiring layer, the method comprising at least the following steps:

[0008] Providing a supporting substrate, and sequentially forming a diffusion barrier layer and a metal seed layer on the supporting substrate;

[0009] Coating a photoresist layer on the metal seed layer, and forming a filling window in the photoresist layer through exposure and development processes;

[0010] Forming a metal wire layer and a buffer layer in sequence on the metal seed layer of the filling window by electroplating, wherein the surface of the buffer layer has a plurality of first pores extending into the interior thereof;

[0011] A stacked structure of at least two protective layers is sequentially formed on the buffer layer by an electroplating process, and a cleaning process is performed between the formation of two adjacent protective layers, wherein the surface of the first protective layer has a second pore connected to the first pore, and the outermost protective layer covers the first pore and the second pore;

[0012] removing the photoresist layer, and removing the metal seed layer and the diffusion barrier layer not covered by the metal line layer;

[0013] Bond the bonding wire to the protection layer for electrical extraction.

[0014] Optionally, the laminate structure includes two protective layers, the thickness of the first protective layer is between 18% and 22% of the total thickness of the laminate structure, and the thickness of the second protective layer is between 78% and 82% of the total thickness of the laminate structure.

[0015] Optionally, the thickness of the laminated structure is between 0.2 μm and 1.2 μm.

[0016] Optionally, the laminated structure includes two layers of the protective layer, the thickness of the first layer of the protective layer is between 0.1 μm and 0.2 μm, and the thickness of the second layer of the protective layer is between 0.1 μm and 1.0 μm.

[0017] Optionally, the current density used for electroplating the first protective layer is between 0.3ASD and 0.34ASD, and the electroplating time is between 30s and 60s; the current density used for electroplating the second protective layer is between 0.1ASD and 0.6ASD, and the electroplating time is between 10s and 580s.

[0018] Optionally, the material of the diffusion barrier layer includes one or more of Ti, TiN, Ta, TaN, TiW, Cr, the material of the metal seed layer includes Cu, the material of the metal wire layer includes aluminum, aluminum alloy, copper or copper alloy, the material of the buffer layer includes Ni, and the material of the protective layer includes Au.

[0019] Optionally, the cleaning liquid used in the cleaning process is deionized water (DIW).

[0020] The present invention also provides a rewiring layer, the rewiring layer at least comprising:

[0021] a diffusion barrier layer having opposing first and second sides;

[0022] a metal seed layer, located on the first surface of the diffusion barrier layer;

[0023] a metal line layer located on the metal seed layer;

[0024] A buffer layer located on the metal wire layer, wherein a surface of the buffer layer has a plurality of first pores extending into the interior thereof;

[0025] A laminated structure located on the buffer layer, the laminated structure comprising at least two protective layers, wherein a surface of the first protective layer has a second pore connected to the first pore, and the outermost protective layer covers the first pore and the second pore;

[0026] Bonding wires electrically lead out of the metal wire layer.

[0027] Optionally, the laminate structure includes two protective layers, the thickness of the first protective layer is between 18% and 22% of the total thickness of the laminate structure, and the thickness of the second protective layer is between 78% and 82% of the total thickness of the laminate structure.

[0028] Optionally, the thickness of the laminated structure is between 0.2 μm and 1.2 μm.

[0029] Optionally, the laminated structure includes two layers of the protective layer, the thickness of the first layer of the protective layer is between 0.1 μm and 0.2 μm, and the thickness of the second layer of the protective layer is between 0.1 μm and 1.0 μm.

[0030] Optionally, the material of the diffusion barrier layer includes one or more of Ti, TiN, Ta, TaN, TiW, Cr, the material of the metal seed layer includes Cu, the material of the metal wire layer includes aluminum, aluminum alloy, copper or copper alloy, the material of the buffer layer includes Ni, and the material of the protective layer includes Au.

[0031] Optionally, the rewiring layer further includes an insulating layer, and the insulating layer is located on the second surface of the diffusion barrier layer.

[0032] Optionally, the thickness of the metal wire layer is between 3 μm and 6 μm, and the thickness of the buffer layer is between 1 μm and 4 μm.

[0033] As described above, the preparation method and structure of the rewiring layer of the present invention form the laminated structure on the buffer layer through an electroplating process combined with a cleaning process, that is, a protective layer structure of a multi-layer structure, and the outermost protective layer covers the first pores and the second pores. There are no through pores between the laminated structure and the buffer layer, thereby effectively improving the continuity of the protective layer structure, thereby improving the adhesion between the buffer layer and the laminated structure, improving the stability of the rewiring layer, and in the subsequent WB process, it is not easy to peel off between the buffer layer and the laminated structure, thereby effectively improving the product yield of the rewiring layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic flow chart of the method for preparing the redistribution layer of the present invention.

[0035] Figures 2 to 9 It is a schematic structural diagram showing the steps of the method for preparing a rewiring layer in the prior art, wherein Figure 7 Display as Figure 6 A partial enlarged view of the middle A. Fig. 9 Display as Figure 7 A partial enlarged view of point B in the middle.

[0036] Figures 10 to 14 It is a schematic structural diagram showing the steps of the method for preparing a rewiring layer of the present invention, wherein Fig.11 Display as Fig.10 A partial enlarged view of point C in the middle. Fig.14 Also shown is a schematic structural diagram of the rewiring layer of the present invention.

[0037] Fig.15 The SEM image of the rewiring layer in the prior art is shown, and the black dots of different sizes in the image are the black spots and / or pits on the surface of the protective layer.

[0038] Component number description

[0039] 10 Support substrate

[0040] 100 Support Layer

[0041] 101 Separation Layer

[0042] 102 Insulation layer

[0043] 11 Diffusion barrier

[0044] 12 Metal Seed Layer

[0045] 13 Photoresist layer

[0046] 130 Fill Window

[0047] 14 Metal Wire Layers

[0048] 15 Buffer layer

[0049] 16 Laminated structure

[0050] 160 protective layer

[0051] 17 Bonding wire

[0052] 18 First Pore

[0053] 19 Second Pore

[0054] Steps S1 to S6 DETAILED DESCRIPTION

[0055] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0056] See also Figures 1 to 14 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0057] Embodiment 1

[0058] like Figures 2 to 9 As shown, it is a schematic diagram of the process steps of the existing RDL (rewiring layer) process, and the preparation process is as follows:

[0059] like Figure 2 As shown, a supporting substrate 10 is first provided;

[0060] like Figure 3 As shown, a diffusion barrier layer 11 and a metal seed layer 12 are then formed on the supporting substrate 10 in sequence;

[0061] like Figure 4 As shown, a photoresist layer 13 is then coated on the metal seed layer 12, and a filling window 130 is formed in the photoresist layer 13 through exposure and development processes;

[0062] like Figure 5 As shown, a metal line layer 14 is then formed on the metal seed layer 12 filling the window 130;

[0063] like Figure 6 As shown, a buffer layer 15 is formed on the metal wire layer 14 by electroplating process. Figure 7 As shown, after analysis and research, the inventors found that the first pores 18 would be formed in the process of electroplating to form the buffer layer 15. The first pores 18 may be formed in the buffer layer 15, or may be formed on the surface of the buffer layer 15 and extend inward from its surface. Some of the first pores 18 extending inward from its surface are shallower and smaller, while others are deeper and larger. In the SEM image, the shallower and smaller voids appear as black spots, while the deeper and larger voids appear as pits.

[0064] like Figure 8 As shown, a protective layer 160 is formed on the buffer layer 15 by electroplating. Fig. 9 As shown, the inventors found that based on the morphology of the buffer layer 15 having the first pores 18 extending from the surface to the inside thereof, the morphology will be transferred to the protective layer 160. During the electroplating process, the surface of the protective layer above the shallower and smaller first pores 18 will form shallower and smaller second pores 19. At this time, the protective layer 160 with these shallower and smaller second pores 19 can cover the first pores 18 on the buffer layer 15 below it. On the other hand, the surface of the protective layer above the deeper and larger first pores 18 will form deeper and larger second pores 19, some of which even penetrate the protective layer 160 and are connected to the first pores 18, thereby resulting in poor surface continuity of the protective layer 160 and low hardness of the protective layer, reducing the adhesion between the buffer layer 15 and the protective layer 160, and seriously affecting the stability of the rewiring layer. In the subsequent wire bonding process, peeling is prone to occur between the buffer layer 15 and the protective layer 160, and the product yield of the rewiring layer is reduced.

[0065] Based on the above findings and after research and analysis, the inventors proposed a method for preparing a rewiring layer, such as Figure 1As shown, the above-mentioned problem that the surface discontinuity and low hardness of the protective layer affect the stability of the rewiring layer and reduce the product yield of the rewiring layer is solved. The preparation method of the rewiring layer of this embodiment is described in detail below with reference to the accompanying drawings.

[0066] like Figure 1 and Figures 2 to 3 As shown, step S1 is first performed to provide a support substrate 10 , and to sequentially form a diffusion barrier layer 11 and a metal seed layer 12 on the support substrate 10 .

[0067] like Figure 2 As shown, as an example, the support substrate 10 includes a support layer 100 , a separation layer 101 and an insulating layer 102 in sequence from bottom to top.

[0068] The support layer 100 includes one of a glass layer, a metal layer, a semiconductor layer, a polymer layer and a ceramic layer. In this embodiment, the support layer 100 is a glass layer, which has a low cost, is easy to form the separation layer 101 on its surface, and can reduce the difficulty of the subsequent peeling process.

[0069] The separation layer 101 includes a polymer layer or an adhesive layer. The polymer layer or the adhesive layer is firstly coated on the surface of the support layer 100 by a spin coating process, and then cured and formed by an ultraviolet curing process or a thermal curing process.

[0070] In this embodiment, the polymer layer includes an LTHC light-to-heat conversion layer. When the support layer 100 is subsequently peeled off, the LTHC light-to-heat conversion layer can be heated based on a laser to separate the rewiring layer and the support layer 1000 from the LTHC light-to-heat conversion layer.

[0071] After the insulating layer 102 is separated from the supporting layer 100 , it is used to form an isolation layer for the bumps connected to the chip.

[0072] like Figure 3As shown, the diffusion barrier layer 11 can be prepared by existing known methods, such as sputtering, electrochemical plating, physical vapor deposition, chemical vapor deposition and other physical or chemical methods. The material of the diffusion barrier layer 11 can be one or more of Ti, TiN, Ta, TaN, TiW and Cr. Since the metal wire layer in the general rewiring layer has a very high diffusion coefficient, when the rewiring layer is bonded to the wafer, the high diffusion coefficient of the metal wire layer will cause the metal ions to diffuse into the device structure of the wafer, which will affect the performance of the wafer. Therefore, in order to avoid the ion diffusion of the metal wire layer, when preparing the rewiring layer, it is necessary to first prepare a layer of the diffusion barrier layer 11 on the supporting substrate to prevent the metal ions from diffusing into the wafer; in addition, it is also to improve the adhesion between the metal wire layer and the supporting substrate 10 when the rewiring layer is prepared later. In this embodiment, Ti is selected as the diffusion barrier layer 11, and the conventional sputtering method is selected to deposit the diffusion barrier layer 11. The Ti layer is deposited by sputtering. The process is easy to implement and the adhesion between the Ti layer and the supporting substrate 10 is strong.

[0073] As an example, the metal wire layer is generally formed by electroplating, and the key to electroplating is to generate current through the metal layer on the surface to deposit metal. For the diffusion barrier layer 11, it needs to achieve the function of blocking diffusion and improving adhesion. The selected material has a low conductivity, so it is necessary to form a metal layer with a high conductivity to serve as the metal seed layer 12 for electroplating the metal wire layer. Figure 3 As shown, the metal seed layer 12 is formed on the diffusion barrier layer 11. The material of the metal seed layer 12 can be Cu, and the metal seed layer 12 can be formed by sputtering.

[0074] like Figure 1 and Figure 4 As shown, step S2 is then performed to coat a photoresist layer 13 on the metal seed layer 12 , and form a filling window 130 in the photoresist layer 13 through exposure and development processes.

[0075] As an example, the method for forming the patterned photoresist layer 13 is as follows: the photoresist is uniformly coated on the surface of the metal seed layer 12, and then the supporting substrate 10 covered with the photoresist is transferred from the coating machine to an oven for coating and baking to evaporate the water in the photoresist and fix the photoresist. Ultraviolet light is irradiated through the pattern on the mask plate to the surface of the supporting substrate coated with the photoresist, and the photoresist is deformed after being irradiated by the ultraviolet light, and the photoresist is corroded by the developer. After cleaning, a pattern consistent with or complementary to that on the mask plate is left, thereby forming a patterned photoresist layer 13.

[0076] like Figure 1 and Figure 6As shown, step S3 is then performed to sequentially form a metal wire layer 14 and a buffer layer 15 on the metal seed layer 12 of the filling window 130 by electroplating. The surface of the buffer layer 15 has a plurality of first pores 18 extending into the interior thereof.

[0077] like Figure 5 As shown, as an example, a metal wire layer 14 is first formed on the metal seed layer 12 of the filling window 130 by electroplating. The material of the metal wire layer 14 includes aluminum, aluminum alloy, copper or copper alloy. In this embodiment, the material of the metal wire layer 14 is copper. The thickness of the metal wire layer 14 is between 3μm and 6μm.

[0078] like Figure 6 As shown, as an example, a buffer layer 15 is formed on the metal wire layer 14 by an electroplating process. The material of the buffer layer 15 includes Ni. The thickness of the buffer layer 15 is between 1μm and 4μm. Since the metal wire layer 14 needs to be electrically led out in the subsequent bonding wire lead-out process (called WB process), in order to alleviate the impact of high heat and high pressure in the WB process on the metal wire layer 14, a buffer layer 15 with relatively soft hardness is provided on the metal wire layer 14. Since the buffer layer 15 is generally soft and deposited at a relatively fast speed, it is easy to form the first pores 18 (such as Figure 7 shown).

[0079] like Figure 1 and Fig.10 As shown, step S4 is then performed, in which a stacked structure 16 of at least two protective layers 160 is sequentially formed on the buffer layer 15 using an electroplating process, and a cleaning process is performed between the formation of two adjacent layers of the protective layers 160, wherein the surface of the first protective layer 160 has a second pore 19 connected to the first pore 18, and the outermost protective layer 160 covers the first pore 18 and the second pore 19.

[0080] In this embodiment, the laminated structure 16 is formed on the buffer layer 15 by combining an electroplating process with a cleaning process, i.e., a multi-layer protective layer structure, and the outermost protective layer covers the first pore and the second pore, and there is no through pore between the laminated structure and the buffer layer, thereby effectively improving the continuity of the protective layer structure, thereby improving the adhesion between the buffer layer and the laminated structure, improving the stability of the rewiring layer, and in the subsequent WB process, it is not easy to peel off between the buffer layer and the laminated structure, thereby effectively improving the product yield of the rewiring layer. Fig.11As shown, the working process of using the electroplating process combined with the cleaning process of this embodiment to form a continuous laminated structure with better performance is roughly as follows: since the first pores 18 are formed on the surface of the buffer layer when the buffer layer 15 is formed by electroplating, when the first protective layer 160 is formed on the buffer layer 15, the protective layer plating solution will enter the first pores 18 and undergo a replacement reaction with the material of the buffer layer 15, forming a protective layer material with poor adhesion in the first pores. At the same time, as the first protective layer 160 is slowly deposited, the morphology of the first pores 18 on the surface of the buffer layer 15 will be transferred to the first protective layer 160. On the surface of the first protective layer 160, the larger and deeper first pores 18 may cause the second pores 19 connected to the first pores to be formed on the surface of the first protective layer 160, and the smaller and shallower first pores 18 may cause the smaller and shallower second pores 19 to be formed on the surface of the first protective layer 160; before forming the second protective layer 160, the first protective layer 160 needs to be cleaned. During the cleaning process, the cleaning liquid will wash away the protective layer material with poor adhesion formed in the first pores 18 and the protective layer plating liquid in the second pores 19, and form cleaning pores in the first pores 18 and the second pores 19. When the second protective layer 160 is electroplated, according to the electroplating mechanism, the second protective layer 160 will be quickly electroplated on the first protective layer 160. Since the second pore 19 is a liquid sealing layer of the cleaning liquid, which is pure water or deionized water, the second protective layer 160 will be quickly deposited in the second pore 19. When the surface of the second pore 19 is filled, the second protective layer 160 on the second pore 19 will be quickly deposited upward, thereby greatly reducing the surface morphology of the first protective layer 160 from being transferred to the second protective layer 160, so that the second protective layer 160 The width and depth of the pores on the surface are reduced; then a second cleaning process is performed, and then a third protective layer 160 is formed. This process is the same as the mechanism of forming the second protective layer 160. After the deposition of the third protective layer 160, the morphology of the second protective layer 160 is further reduced and transferred to the third protective layer 160, and so on, until the formed laminated structure 16 completely covers the first pore 18 and the second pore 19, that is, the formed laminated structure 16 does not contain pores connected to the first pore 18, thereby forming a laminated structure 16 with better continuity.

[0081] As an example, the thickness of the laminated structure 16 is between 0.2 μm and 1.2 μm. Fig.11As shown, in this embodiment, the stacked structure 16 includes two layers of protective layers 160, the thickness of the first protective layer 160 is between 0.1 μm and 0.2 μm, and the thickness of the second protective layer 160 is between 0.1 μm and 1.0 μm. Preferably, the current density used for electroplating the first protective layer 160 is between 0.3 ASD and 0.34 ASD, and the electroplating time is between 30s and 60s; the current density used for electroplating the second protective layer 160 is between 0.1 ASD and 0.6 ASD, and the electroplating time is between 10s and 580s.

[0082] like Fig.10 As shown, as an example, when the laminate structure 16 includes two layers of the protective layer 160, the thickness of the first layer of the protective layer 160 can be selected to be between 18% and 22% of the total thickness of the laminate structure 16, and the thickness of the second layer of the protective layer 160 can be selected to be between 78% and 82% of the total thickness of the laminate structure 16.

[0083] Since the buffer layer 15 is relatively soft, especially when the material of the buffer layer 15 is Ni, Ni is relatively soft and easily oxidized, it is necessary to form the protective layer 160 which is not easy to oxidize and has a relatively high hardness on the buffer layer 15 to protect the buffer layer 15 from oxidation and facilitate the bonding of the bonding wire in the subsequent WB process. In this embodiment, the material of the protective layer 160 is Au.

[0084] like Figure 1 and Fig.13 As shown, step S5 is then performed to remove the photoresist layer 13 , and remove the metal seed layer 12 and the diffusion barrier layer 11 that are not covered by the metal wire layer 14 .

[0085] like Fig.12 As shown, as an example, in actual production, a process temperature higher than 200° C. is generally used to perform an ashing process in an oxygen and fluorine mixed process gas to remove the patterned photoresist layer 13 .

[0086] like Fig.13 As shown, as an example, a wet etching process is used to remove the metal seed layer 12 and the diffusion barrier layer 11 that are not covered by the metal wire layer 14. Wet etching has become a commonly used etching method due to its fast etching rate and low cost. Since the materials used for the metal seed layer 12 and the diffusion barrier layer 11 are different, that is, the etching ratios are different, different etching solutions need to be selected. Those skilled in the art can proceed as needed. Of course, in other embodiments, other processes can also be used to remove the metal seed layer 12 and the diffusion barrier layer 11, which are not limited here.

[0087] like Figure 1 and Fig.14 As shown, step S6 is finally performed to bond the bonding wire 17 to the protection layer 160 for electrical extraction.

[0088] As an example, the bonding method is any one of ultrasonic bonding, thermal compression bonding and thermosonic bonding. In this embodiment, thermal compression bonding is used for bonding.

[0089] As an example, after forming the above structure, it may also include forming a dielectric layer covering the bonding wire 17, the stacked structure 16, the buffer layer 15, the metal wire layer 14, the metal seed layer 12 and the diffusion barrier layer 11, and then separating the rewiring layer from the support layer 100 through the separation layer 101.

[0090] Embodiment 2

[0091] like Fig.14 As shown, this embodiment provides a rewiring layer, the structure of which can be prepared by the preparation method of the above-mentioned embodiment 1, but can also be prepared by other methods, which is not limited here. The beneficial effects brought by the rewiring layer of this embodiment can be referred to in the description of embodiment 1, and will not be repeated in this embodiment.

[0092] like Fig.11 and Fig.14 As shown, the rewiring layer at least includes:

[0093] The diffusion barrier layer 11 has a first surface and a second surface opposite to each other;

[0094] A metal seed layer 12, located on a first surface of the diffusion barrier layer 11;

[0095] A metal wire layer 14 located on the metal seed layer 12;

[0096] A buffer layer 15 located on the metal wire layer 14, wherein the surface of the buffer layer 15 has a plurality of first pores 18 extending into the interior thereof;

[0097] A laminated structure 16 located on the buffer layer 15, the laminated structure 16 comprising at least two protective layers 160, wherein a surface of the first protective layer 160 has a second pore 19 connected to the first pore 18, and the outermost protective layer 160 covers the first pore 18 and the second pore 19;

[0098] The bonding wires 17 are electrically led out of the metal wire layer 14 .

[0099] As an example, the laminated structure 16 includes two layers of protective layers 160 , the thickness of the first layer of protective layer 160 is between 18% and 22% of the total thickness of the laminated structure 16 , and the thickness of the second layer of protective layer 160 is between 78% and 82% of the total thickness of the laminated structure 16 .

[0100] As an example, the thickness of the laminated structure 16 is between 0.2 μm and 1.2 μm. Preferably, the laminated structure 16 includes two layers of the protective layer 160, the thickness of the first protective layer 160 is between 0.1 μm and 0.2 μm, and the thickness of the second protective layer 160 is between 0.1 μm and 1.0 μm.

[0101] As an example, the material of the diffusion barrier layer 11 includes one or more of Ti, TiN, Ta, TaN, TiW, and Cr, the material of the metal seed layer 12 includes Cu, the material of the metal wire layer 14 includes aluminum, aluminum alloy, copper, or copper alloy, the material of the buffer layer 15 includes Ni, and the material of the protective layer 160 includes Au.

[0102] like Fig.14 As shown, as an example, the rewiring layer further includes an insulating layer 102 , and the insulating layer 102 is located on the second surface of the diffusion barrier layer 11 .

[0103] As an example, the thickness of the metal wire layer 14 is between 3 μm and 6 μm, and the thickness of the buffer layer 15 is between 1 μm and 4 μm.

[0104] In summary, the present invention provides a method for preparing a rewiring layer and its structure, wherein the laminated structure is formed on the buffer layer by combining an electroplating process with a cleaning process, i.e., a protective layer structure of a multi-layer structure, and the outermost protective layer covers the first pore and the second pore, and there is no through pore between the laminated structure and the buffer layer, thereby effectively improving the continuity of the protective layer structure, thereby improving the adhesion between the buffer layer and the laminated structure, improving the stability of the rewiring layer, and in the subsequent WB process, the buffer layer and the laminated structure are not prone to peeling, thereby effectively improving the product yield of the rewiring layer. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0105] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for preparing a rewiring layer, characterized in that: The preparation method comprises at least the following steps: Providing a supporting substrate, and sequentially forming a diffusion barrier layer and a metal seed layer on the supporting substrate; Coating a photoresist layer on the metal seed layer, and forming a filling window in the photoresist layer through exposure and development processes; Forming a metal wire layer and a buffer layer in sequence on the metal seed layer of the filling window by electroplating, wherein the surface of the buffer layer has a plurality of first pores extending into the interior thereof; A stacked structure of at least two protective layers is sequentially formed on the buffer layer by an electroplating process, and a cleaning process is performed between the formation of two adjacent protective layers, wherein the surface of the first protective layer has a second pore connected to the first pore, and the outermost protective layer covers the first pore and the second pore; removing the photoresist layer, and removing the metal seed layer and the diffusion barrier layer not covered by the metal line layer; Bond the bonding wire to the protection layer for electrical extraction.

2. The method for preparing a redistribution layer according to claim 1, characterized in that: The laminated structure comprises two protective layers, the thickness of the first protective layer is between 18% and 22% of the total thickness of the laminated structure, and the thickness of the second protective layer is between 78% and 82% of the total thickness of the laminated structure.

3. The method for preparing a redistribution layer according to claim 1, characterized in that: The thickness of the laminated structure is between 0.2 μm and 1.2 μm.

4. The method for preparing a redistribution layer according to claim 3, characterized in that: The laminated structure comprises two protective layers, the thickness of the first protective layer is between 0.1 μm and 0.2 μm, and the thickness of the second protective layer is between 0.1 μm and 1.0 μm.

5. The method for preparing a redistribution layer according to claim 4, characterized in that: The current density used for electroplating the first protective layer is between 0.3ASD and 0.34ASD, and the electroplating time is between 30s and 60s; the current density used for electroplating the second protective layer is between 0.1ASD and 0.6ASD, and the electroplating time is between 10s and 580s.

6. The method for preparing a redistribution layer according to claim 1, characterized in that: The material of the diffusion barrier layer includes one or more of Ti, TiN, Ta, TaN, TiW, and Cr, the material of the metal seed layer includes Cu, the material of the metal wire layer includes aluminum, aluminum alloy, copper, or copper alloy, the material of the buffer layer includes Ni, and the material of the protective layer includes Au.

7. The method for preparing a redistribution layer according to claim 1, characterized in that: The cleaning liquid used in the cleaning process is deionized water (DIW).

8. A rewiring layer, characterized in that: The rewiring layer is prepared by the method for preparing the rewiring layer according to any one of claims 1 to 7, wherein the rewiring layer at least comprises: a diffusion barrier layer having opposing first and second sides; a metal seed layer, located on the first surface of the diffusion barrier layer; a metal line layer located on the metal seed layer; A buffer layer located on the metal wire layer, wherein a surface of the buffer layer has a plurality of first pores extending into the interior thereof; A laminated structure located on the buffer layer, the laminated structure comprising at least two protective layers, wherein a surface of the first protective layer has a second pore connected to the first pore, and the outermost protective layer covers the first pore and the second pore; Bonding wires electrically lead out of the metal wire layer.

9. The rewiring layer according to claim 8, characterized in that: The laminated structure comprises two protective layers, the thickness of the first protective layer is between 18% and 22% of the total thickness of the laminated structure, and the thickness of the second protective layer is between 78% and 82% of the total thickness of the laminated structure.

10. The rewiring layer according to claim 8, characterized in that: The thickness of the laminated structure is between 0.2 μm and 1.2 μm.

11. The rewiring layer according to claim 10, characterized in that: The laminated structure comprises two protective layers, the thickness of the first protective layer is between 0.1 μm and 0.2 μm, and the thickness of the second protective layer is between 0.1 μm and 1.0 μm.

12. The rewiring layer according to claim 8, characterized in that: The material of the diffusion barrier layer includes one or more of Ti, TiN, Ta, TaN, TiW, and Cr, the material of the metal seed layer includes Cu, the material of the metal wire layer includes aluminum, aluminum alloy, copper, or copper alloy, the material of the buffer layer includes Ni, and the material of the protective layer includes Au.

13. The rewiring layer according to claim 8, characterized in that: The rewiring layer further includes an insulating layer, and the insulating layer is located on the second surface of the diffusion barrier layer.

14. The rewiring layer according to claim 8, characterized in that: The thickness of the metal wire layer is between 3 μm and 6 μm, and the thickness of the buffer layer is between 1 μm and 4 μm.

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