A packaging structure and a method of manufacturing the same

Abstract

The application provides a packaging structure and a preparation method thereof. The packaging structure comprises a substrate, a first heavy wiring structure, a first type of dielectric structure and a second type of dielectric structure. The first heavy wiring structure is arranged on the substrate in a spaced manner. The first type of dielectric structure is formed on the substrate and covers the side surface of the first heavy wiring structure. The second type of dielectric structure is arranged on the substrate in a spaced manner, the side surface of the second type of dielectric structure is directly in contact with the first type of dielectric structure, and one second type of dielectric structure is arranged between every two first heavy wiring structures. The material of the first type of dielectric structure is different from the material of the second type of dielectric structure, and the ratio of the dielectric constant of the material of the first type of dielectric structure to the dielectric constant of the material of the second type of dielectric structure is in the range of 1.3-2. The packaging structure can reduce the parasitic capacitance between lines, avoid signal crosstalk and delay, reduce dielectric loss and improve the integrity of high-frequency signals.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor packaging, in particular to a packaging structure and a preparation method thereof. BACKGROUND

[0002] With the rapid development of 5G communication, artificial intelligence, high-performance computing and millimeter wave radar technologies, higher requirements are put forward for the signal transmission rate and integrity of semiconductor packaging technology. In particular, as the working frequency gradually enters the millimeter wave stage, the loss of signals in the transmission process becomes a key problem affecting performance.

[0003] The current semiconductor packaging technology generally adopts Fan-Out Wafer-Level Packaging (FOWLP) and other technologies to realize high-density interconnection between chips and the outside through the redistribution layer (RDL) therein. However, the dielectric material based on polyimide (PI), epoxy resin or silicon dioxide (SiO2) has a relatively high relative dielectric constant (k value) (usually k>3.0) and a relatively large dielectric loss factor (Dissipation Factor, Df or tanδ) (usually in the order of 0.01~0.02), which will increase the parasitic capacitance between lines under high-frequency conditions, resulting in signal crosstalk and delay; at the same time, it will cause serious signal attenuation due to its large dielectric loss factor, which will seriously affect the integrity of high-frequency signals.

[0004] On the other hand, conductor loss will also affect the integrity of the signal. The conductor of the traditional redistribution layer is usually formed by electroplating copper process, and the roughness of its surface is relatively high (usually >200nm). In high-frequency applications, the current is concentrated on the surface of the conductor, and the rough surface will exacerbate electron scattering, significantly increase the transmission loss of the signal, and seriously affect the integrity of high-frequency signals. In addition, copper conductors are prone to electromigration under high current load, resulting in voids or even breakage of the conductive lines.

[0005] Therefore, the design of the existing semiconductor packaging structure, such as a single redistribution layer or a simple double redistribution layer, can realize the basic functions, but it is difficult to balance the signal integrity, power consumption and reliability when dealing with ultra-high frequency and high-power scenarios. SUMMARY

[0006] Therefore, the present application provides a packaging structure and a preparation method thereof, aiming to solve the technical problem of damaged high-frequency signal integrity in the prior art.

[0007] The technical scheme provided by the present application is as follows:

[0008] In a first aspect, the present application provides a packaging structure, comprising:

[0009] a substrate;

[0010] a first redistribution structure, disposed on a first surface of the substrate;

[0011] a first type of dielectric structure on the first surface of the substrate, formed on the first surface of the substrate and covering side surfaces of the first redistribution structure;

[0012] a second type of dielectric structure on the first surface of the substrate, disposed on the first surface of the substrate, with side surfaces directly contacting the first type of dielectric structure on the first surface of the substrate, and one second type of dielectric structure on the first surface of the substrate being disposed between every two first redistribution structures;

[0013] wherein the material of the first type of dielectric structure on the first surface of the substrate and the material of the second type of dielectric structure on the first surface of the substrate are different, and the ratio of the dielectric constant of the material of the first type of dielectric structure on the first surface of the substrate to the dielectric constant of the material of the second type of dielectric structure on the first surface of the substrate is in the range of 1.3-2.

[0014] Further, the second surface of the substrate comprises:

[0015] a second redistribution structure, disposed on a second surface of the substrate;

[0016] a first type of dielectric structure on the second surface of the substrate, formed on the second surface of the substrate and covering side surfaces of the second redistribution structure;

[0017] a second type of dielectric structure on the second surface of the substrate, disposed on the second surface of the substrate, with side surfaces directly contacting the first type of dielectric structure on the second surface of the substrate, and one second type of dielectric structure on the second surface of the substrate being disposed between every two second redistribution structures.

[0018] Further, the first type of dielectric structure on the first surface of the substrate and the first type of dielectric structure on the second surface of the substrate are selected from: epoxy, polyimide, bismaleimide-triazine, build-up insulating film, polyphenyl ether, polypropylene, polymethyl acrylate, combinations of the above materials, or other suitable insulating materials;

[0019] the second type of dielectric structure on the first surface of the substrate and the second type of dielectric structure on the second surface of the substrate are selected from fluorine-based low-k dielectric materials.

[0020] Further, the cross-sectional shape of the second type of medium structure of the first surface of the substrate and the second surface of the substrate is rectangular, inverted trapezoidal, trapezoidal or a combination of any two thereof.

[0021] Further, the packaging structure further comprises a composite plating layer.

[0022] The composite plating layer is formed on top of the first re-wiring structure and the second re-wiring structure, and the side surface of the composite plating layer is covered by the first type of medium structure of the first surface of the substrate or the first type of medium structure of the second surface of the substrate.

[0023] Further, the material of the composite plating layer is a material with a surface roughness less than 50 nm.

[0024] In another aspect, the application further provides a method for preparing a packaging structure, for forming the packaging structure described above, the method for preparing a packaging structure comprising the following steps:

[0025] Step S11: growing a first re-wiring structure on the first surface of the substrate, the first re-wiring structure being arranged on the first surface of the substrate at intervals;

[0026] Step S12: growing a first type of medium structure of the first surface of the substrate on the first surface of the substrate, the first type of medium structure of the first surface of the substrate covering the side surface of the first re-wiring structure;

[0027] Step S13: growing a second type of medium structure of the first surface of the substrate on the first surface of the substrate, the side surface of the second type of medium structure of the first surface of the substrate being in direct contact with the first type of medium structure of the first surface of the substrate, and one second type of medium structure of the first surface of the substrate being arranged between every two first re-wiring structures;

[0028] The material of the first type of medium structure of the first surface of the substrate and the material of the second type of medium structure of the first surface of the substrate are different, and the ratio of the dielectric constant of the material of the first type of medium structure of the first surface of the substrate to the dielectric constant of the material of the second type of medium structure of the first surface of the substrate is in the range of 1.3-2.

[0029] Further, the step of forming the first re-wiring structure comprises:

[0030] Step S101: growing a first metal structure on the first surface of the substrate, the first metal structure being arranged on the first surface of the substrate at intervals;

[0031] Step S102: growing a second metal structure on top of the first metal structure, a side surface of the second metal structure being covered by the first-type medium structure of the first surface of the substrate.

[0032] Further, the step of forming the first-type medium structure of the first surface of the substrate comprises:

[0033] Step S103: growing a first medium structure on the first surface of the substrate, the first medium structure covering the first metal structure and etching a first cavity and a second cavity on top of the first metal structure and between two adjacent first metal structures respectively, the etching depth of the second cavity being greater than that of the first cavity.

[0034] Step S104: growing a third medium structure on top of the first medium structure, the third medium structure covering the side surface of the second metal structure.

[0035] Further, the step of forming the second-type medium structure of the first surface of the substrate comprises:

[0036] Step S105: growing a second medium structure on the first surface of the substrate, and the second medium structure filling the second cavity.

[0037] Step S106: growing a fourth medium structure on top of the second medium structure.

[0038] Further, after the step S13, further comprising:

[0039] Step S107: growing a composite plating layer on top of the first redistribution structure, a side surface of the composite plating layer being covered by the first-type medium structure of the first surface of the substrate.

[0040] Step S108: covering a surface of a packaging structure formed on the first surface of the substrate with a temporary bonding film.

[0041] Step S109: thinning the second surface of the substrate.

[0042] Step S110: sequentially forming a second redistribution structure, a first-type medium structure of the second surface of the substrate, a second-type medium structure of the second surface of the substrate and the composite plating layer on the second surface of the substrate to form a packaging structure consistent with the first surface on the second surface of the substrate.

[0043] Step S111: removing the temporary bonding film to form a complete packaging structure.

[0044] The scheme provided in the application has the following beneficial effects:

[0045] 1. The packaging structure provided by the application, by arranging the second type of medium structure between the two adjacent re-distribution structures and directly contacting the first type of medium structure, the dielectric constant of the material of the second type of medium structure is lower than that of the material of the first type of medium structure, and the ratio of the dielectric constants of the two is in the range of 1.3-2, replacing the traditional high dielectric constant material, so that when the packaging structure provided by the application is applied in the high frequency band, the parasitic capacitance between the lines is reduced, avoiding signal crosstalk and delay; and the medium loss can be greatly reduced, avoiding serious signal attenuation of high frequency signals, and improving the integrity of high frequency signals.

[0046] 2. The packaging structure provided by the application, by arranging a composite plating layer on the top of the re-distribution structure, and the material of the composite plating layer has small roughness, effectively reducing the roughness of the conductor surface, forming a smooth conductor surface, so that the packaging structure of the application can reduce electron scattering and reduce signal transmission loss when applied in a high frequency scenario, further improving the integrity of high frequency signals; and by arranging the composite plating layer, the application can avoid the electromigration phenomenon of traditional copper conductors under high current load, and also avoid the generation of cavities or even the rupture of the wire.

[0047] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0049] Figure 1 The cross-sectional schematic view of the packaging structure provided by the embodiment of the application;

[0050] Figure 2 The cross-sectional schematic view of the packaging structure provided by another embodiment of the application;

[0051] Figure 3 The flowchart of the preparation method of the packaging structure provided by the embodiment of the application;

[0052] Figure 4 The cross-sectional schematic view of the packaging structure formed after the step S101 of the embodiment of the application is executed;

[0053] Figure 5 The cross-sectional schematic view of the packaging structure formed after the step S103 of the embodiment of the application is executed;

[0054] Figure 6 A cross-sectional view of a packaging structure formed after the step S104 is performed is provided for the embodiment of the present application;

[0055] Figure 7 A cross-sectional view of a packaging structure formed after the step S11 is performed is provided for the embodiment of the present application;

[0056] Figure 8 A cross-sectional view of a packaging structure formed after the step S12 is performed is provided for the embodiment of the present application;

[0057] Figure 9 A cross-sectional view of a packaging structure formed after the step S13 is performed is provided for the embodiment of the present application;

[0058] Figure 10 A cross-sectional view of a packaging structure formed after the step S111 is performed is provided for the embodiment of the present application.

[0059] Explanation of reference signs:

[0060] 100: substrate; 200: first heavy wiring structure; 201: first metal structure; 202: second metal structure; 300-1: first type of dielectric structure of a first surface of the substrate; 300-2: first type of dielectric structure of a second surface of the substrate; 301: first dielectric structure; 302: third dielectric structure; 400-1: second type of dielectric structure of the first surface of the substrate; 400-2: second type of dielectric structure of the second surface of the substrate; 401: second dielectric structure; 402: fourth dielectric structure; 500: second heavy wiring structure; 600: composite plating layer. DETAILED DESCRIPTION

[0061] In order to make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will be a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0062] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0063] It should be noted that similar reference numerals and letters refer to like items in the accompanying drawings and as such descriptions of those items need not be repeated with respect to other drawings. It is to be expressly understood that: the specific locations and orientations of the devices and elements as shown in the figures are for purposes of example only and in fact values of these parameters can differ depending on specific application needs. Thus, the structures and devices shown in the present disclosure can be neither necessarily nor exclusively constructed and operative in the particular orientations shown in the figures.

[0064] In the description of the present application, it should be noted that the terms "inner", "outer", "upper", "lower", "vertical" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship commonly placed when the product of the application is used, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0065] Some embodiments of the present application will be described in detail below with reference to the accompanying drawings. The features in the following examples can be combined with each other as long as they do not conflict.

[0066] In view of the defects of the prior art, the technical scheme of the present application is proposed. The technical scheme of the present application will be described in detail below.

[0067] Please refer to Figure 1 , Figure 1 The cross-sectional schematic diagram of the packaging structure provided by the embodiments of the present application is shown.

[0068] The packaging structure comprises a substrate 100, a first redistribution structure 200, a first type of dielectric structure 300-1 on the first surface of the substrate, and a second type of dielectric structure 400-1 on the first surface of the substrate.

[0069] The substrate 100 can be a Si substrate, a SiC substrate, a GaAs substrate or other compound semiconductor materials such as GaN, etc.

[0070] The first redistribution structure 200 is arranged on the first surface of the substrate 100; the first redistribution structure 200 is formed on the first surface of the substrate 100 for realizing the connection between the chip (not shown in the figure) and the outside world, and the first redistribution structure 200 is used to realize the fan-out function of the chip, which can have one or more layers. The material of the first redistribution structure 200 can be nickel, tin, lead, tungsten, chromium, copper, aluminum, gold, molybdenum, silver, palladium and other metal materials, which are not limited in the present application; the shape of the first redistribution structure 200 can be as shown, or other shapes, which are not limited in the present application; the first redistribution structure 200 is arranged on the first surface of the substrate 100 with a spacing, which is used for subsequent filling of the first type of medium structure 300-1 on the first surface of the substrate and the second type of medium structure 400-1 on the first surface of the substrate.

[0071] The first type of medium structure 300-1 on the first surface of the substrate is formed on the first surface of the substrate 100 and covers the side surface of the first redistribution structure 200; the bottom of the first type of medium structure 300-1 on the first surface of the substrate covers and closely contacts the first surface of the substrate 100, and completely covers the side surface of the first redistribution structure 200, which can play an insulating and protective role for the first redistribution structure 200, avoiding the potential risk of short circuit or signal leakage of the first redistribution structure 200.

[0072] The second type of medium structure 400-1 on the first surface of the substrate is arranged between the first surface of the substrate 100, directly contacts the first type of medium structure 300-1 on the first surface of the substrate, and one second type of medium structure 400-1 on the first surface of the substrate is arranged between every two first heavy wiring structures 200; wherein the material of the first type of medium structure 300-1 on the first surface of the substrate is different from the material of the second type of medium structure 400-1 on the first surface of the substrate, and the ratio of the dielectric constant of the material of the first type of medium structure 300-1 on the first surface of the substrate to the dielectric constant of the material of the second type of medium structure 400-1 on the first surface of the substrate is in the range of 1.3-2. The bottom of the second type of medium structure 400-1 on the first surface of the substrate covers and closely contacts the first surface of the substrate 100, is formed between every two first heavy wiring structures 200, and its side directly contacts the first type of medium structure 300-1 on the first surface of the substrate, both of which completely fill the gap between the two adjacent first heavy wiring structures 200. Moreover, the dielectric constant of the material of the second type of medium structure 400-1 on the first surface of the substrate is smaller than the dielectric constant of the material of the first type of medium structure 300-1 on the first surface of the substrate, and the transmission characteristics of high-frequency signals depend on the effective dielectric constant of the surrounding environment. Since the first heavy wiring structure 200 is wrapped in the first type of medium structure 300-1 on the first surface of the substrate, but its electric field lines will extend into the second type of medium structure 400-1 on the first surface of the substrate, the effective dielectric constant is related to the dielectric constant of the material of the first type of medium structure 300-1 on the first surface of the substrate and the second type of medium structure 400-1 on the first surface of the substrate. The first type of medium structure 300-1 on the first surface of the substrate first plays an insulating supporting role for the first heavy wiring structure 200, and then further acts through the second type of medium structure 400-1 on the first surface of the substrate with a lower dielectric constant, reduces the loss of the material, and realizes the integrity of the signal.

[0073] In the embodiment, the second type of dielectric structure 400-1 of the first surface of the substrate is arranged between the two adjacent first re-wiring structures 200 and directly contacts the first type of dielectric structure 300-1 of the first surface of the substrate, the dielectric constant of the material of the second type of dielectric structure 400-1 of the first surface of the substrate is lower than the dielectric constant of the material of the first type of dielectric structure 300-1 of the first surface of the substrate, and the traditional high dielectric constant material is replaced, so that when the packaging structure provided by the application is applied in a high frequency band, the parasitic capacitance between the lines is reduced, the signal crosstalk and delay are avoided, the dielectric loss is greatly reduced, the serious signal attenuation of the high frequency signal is avoided, and the integrity of the high frequency signal is improved; meanwhile, the ratio of the dielectric constant of the material of the first type of dielectric structure 300-1 of the first surface of the substrate to the dielectric constant of the material of the second type of dielectric structure 400-1 of the first surface of the substrate is in the range of 1.3-2, if the ratio is too small, for example, the ratio of the two is equal to 1, it means that the dielectric constants of the two materials are too close, and the function of reducing the loss cannot be realized; if the ratio is too large, for example, the ratio of the two is greater than 2, it means that the stiffness of the material with low dielectric constant may be too poor, and the reliability requirement of the packaging structure cannot be met.

[0074] In one embodiment, the second surface of the substrate 100 comprises: a second re-wiring structure 500, a first type of dielectric structure 300-2 of the second surface of the substrate, and a second type of dielectric structure 400-2 of the second surface of the substrate.

[0075] The second re-wiring structure 500 is arranged on the second surface of the substrate 100 in a spaced manner; the first type of dielectric structure 300-2 of the second surface of the substrate is formed on the second surface of the substrate 100 and covers the side surface of the second re-wiring structure 500; the second type of dielectric structure 400-2 of the second surface of the substrate is arranged on the second surface of the substrate 100 in a spaced manner, the side surface thereof directly contacts the first type of dielectric structure 300-2 of the second surface of the substrate, and one second type of dielectric structure 400-2 of the second surface of the substrate is arranged between every two second re-wiring structures 500. The second surface of the substrate 100 is provided with a packaging structure identical to the first surface of the substrate 100, which will not be described herein; and the dielectric constant of the material of the first type of dielectric structure 300-2 of the second surface of the substrate and the dielectric constant of the material of the second type of dielectric structure 400-2 of the second surface of the substrate are set in the same way as the packaging structure of the first surface of the substrate 100.

[0076] In the embodiment, the package structure of the second surface of the substrate 100 is completely consistent with the first surface of the substrate 100, so that the transmission environment experienced by the signal transmitted from the first surface or the second surface of the substrate 100 is completely consistent and matched, and the signal skew caused by the inconsistent signal transmission path can be avoided, and the second surface of the substrate 100 and the package structure of the first surface of the substrate 100 jointly act to further improve the integrity of the signal.

[0077] In one embodiment, the first type of dielectric structure 300-1 of the first surface of the substrate and the first type of dielectric structure 300-2 of the second surface of the substrate are selected from epoxy, polyimide, bismaleimide-triazine, build-up insulating film, polyphenyl ether, polypropylene, polymethyl acrylate, a combination of the above materials, or other suitable insulating materials; these materials have high mechanical strength, high modulus, good thermal stability, and high adhesion between various substrates and metals, and can provide good support for the first redistribution structure 200 and the second redistribution structure 500.

[0078] The second type of dielectric structure 400-1 of the first surface of the substrate and the second type of dielectric structure 400-2 of the second surface of the substrate are selected from fluorine-based low-k dielectric materials. The fluorine-based low-k dielectric material has very low dielectric constant (about 2.3) and almost negligible dielectric loss factor (usually as low as 0.01 or less), which is arranged between two adjacent first redistribution structures 200 and two adjacent second redistribution structures 500, and is in close contact with the first type of dielectric structure 300-1 of the first surface of the substrate and the first type of dielectric structure 300-2 of the second surface of the substrate, which can reduce interconnection parasitic capacitance and reduce signal crosstalk. The second type of dielectric structure 400-1 of the first surface of the substrate and the second type of dielectric structure 400-2 of the second surface of the substrate can be CYTOP, PTFE or other fluorine-based low-k dielectric materials, which are not limited in the present application.

[0079] In the embodiment, by selecting materials with high mechanical strength, high modulus, good thermal stability, and high adhesion between various substrates and metals as the materials of the first type of dielectric structure 300-1 of the first surface of the substrate and the first type of dielectric structure 300-2 of the second surface of the substrate, good insulating support is provided for the first redistribution structure 200 and the second redistribution structure 500; and by selecting fluorine-based low-k dielectric materials as the materials of the second type of dielectric structure 400-1 of the first surface of the substrate and the second type of dielectric structure 400-2 of the second surface of the substrate, interconnection parasitic capacitance is reduced, signal crosstalk is reduced, signal integrity and package structure reliability are improved.

[0080] In one embodiment, the cross-sectional shape of the second-type medium structure 400-1 on the first surface of the substrate and the second-type medium structure 400-2 on the second surface of the substrate is rectangular, inverted trapezoidal, normal trapezoidal, or a combination of any two thereof. The cross-sectional shape of the second-type medium structure 400-1 on the first surface of the substrate and the second-type medium structure 400-2 on the second surface of the substrate is the filling shape of the fluorine-based low-k medium material, which is achieved by the etching process. If the cross-section is rectangular, the maximum vertical depth can be achieved in a limited lateral area, and the maximum low-k area effect can be obtained in a relatively compact layout. If the cross-section is inverted trapezoidal, the wider top part can provide stable support when serving as a sacrificial layer, and the bottom part not filled by the second-type medium structure 400-1 on the first surface of the substrate and the second-type medium structure 400-2 on the second surface of the substrate is completely filled by the first-type medium structure 300-1 on the first surface of the substrate and the first-type medium structure 300-2 on the second surface of the substrate, respectively. If the cross-section is normal trapezoidal, the top part not filled by the second-type medium structure 400-1 on the first surface of the substrate and the second-type medium structure 400-2 on the second surface of the substrate is completely filled by the first-type medium structure 300-1 on the first surface of the substrate and the first-type medium structure 300-2 on the second surface of the substrate, respectively. Similarly, if the cross-section is a combination of any two of the above, the part not filled by the second-type medium structure 400-1 on the first surface of the substrate and the second-type medium structure 400-2 on the second surface of the substrate is completely filled by the first-type medium structure 300-1 on the first surface of the substrate and the first-type medium structure 300-2 on the second surface of the substrate, respectively. The specific cross-sectional shape can be selected according to the actual process equipment and specific materials, which is not limited in the present application.

[0081] In the present embodiment, by providing a plurality of optional cross-sectional shapes, the shape that is easiest to achieve and has the highest control precision can be flexibly designed according to the actual process equipment and specific materials, thereby reducing the failure risk in the complex process flow and improving the overall manufacturing yield.

[0082] In another embodiment, the packaging structure further comprises a composite plating layer 600; please refer to Figure 2 , Figure 2 A cross-sectional schematic diagram of the packaging structure provided in another embodiment of the present application.

[0083] The composite plating layer 600 is formed on top of the first re-wiring structure 200 and the second re-wiring structure 500, the side surface of the composite plating layer 600 is covered by the first type of medium structure 300-1 on the first surface of the substrate or the first type of medium structure 300-2 on the second surface of the substrate; and the material of the composite plating layer 600 is a material with a surface roughness less than 50 nm. The composite plating layer covers the top of the first re-wiring structure 200 and the second re-wiring structure 500 and is in close contact with them, the side surface of the composite plating layer 600 is covered by the first type of medium structure 300-1 on the first surface of the substrate or the first type of medium structure 300-2 on the second surface of the substrate, forming a close contact, and the first re-wiring structure 200 and the second re-wiring structure 500 at the bottom of the composite plating layer 600 are not exposed; the composite plating layer 600 and the first re-wiring structure 200 and the second re-wiring structure 500 at the bottom thereof together constitute a signal transmission channel. The material of the composite plating layer 600 is selected from a material with a surface roughness less than 50 nm, such as a composite material of cobalt tungsten phosphorus (CoWP) and gold (Au), wherein cobalt tungsten phosphorus serves as a buffer layer and has an amorphous structure without grain boundaries, can effectively block the migration and diffusion of copper atoms, and is an excellent electromigration barrier; gold is extremely stable in chemical properties and is not easy to oxidize, and has strong electromigration resistance; the composite structure of the two provides double protection for the copper conductor and can greatly improve the reliability and service life of the re-wiring layer under high current load, which is particularly important for power chips and high-speed computing chips. The composite plating layer 600 of the embodiment can also be selected from other materials, which are not limited in the present application.

[0084] In the embodiment, by arranging the composite plating layer 600 with a surface roughness less than 50 nm on top of the first re-wiring structure 200 and the second re-wiring structure 500, the conductor surface roughness is reduced from more than 200 nm of conventional electroplated copper to an extremely smooth surface with a surface roughness less than 50 nm, which can significantly reduce electron scattering on the conductor surface and reduce signal transmission loss; this is particularly important for high-frequency signals above 10 GHz, which can reduce the insertion loss by 20%-40% or even more, guarantee signal integrity and transmission distance, and further improve the integrity of high-frequency signals; and by arranging the composite plating layer 600, the electromigration phenomenon of traditional copper conductors under high current load can be avoided, and the hollowing or even breaking of the conductor can also be avoided.

[0085] The present application also provides a preparation method of a packaging structure for forming the packaging structure. Figure 3 , Figure 3 A flowchart of the preparation method of the packaging structure provided in the embodiment of the present application. The preparation method of the packaging structure includes the following steps:

[0086] Step S11: growing a first heavy wiring structure 200 on the first surface of the substrate 100, the first heavy wiring structure 200 being arranged on the first surface of the substrate 100 with a spacing. Please refer to Figure 7 , Figure 7 For the package structure formed after the step S11 is performed, the thickness of the substrate is less than 100 um, a layer of metal is uniformly grown on the first surface of the substrate 100 by a deposition technique, and then a gap is etched between the metals by a photolithography and etching technique to define a required pattern window, and then a metal is selectively grown in the patterned window by an electroplating technique, and finally the first heavy wiring structure 200 is formed. The minimum line width and line spacing of the first heavy wiring structure 200 are both 5 um, and the resistance is less than 1 ohm.

[0087] Step S12: growing a first type of medium structure 300-1 on the first surface of the substrate 100, the first type of medium structure 300-1 on the first surface of the substrate 100 covering the side surface of the first heavy wiring structure 200. Please refer to Figure 8 , Figure 8 For the package structure formed after the step S12 is performed, the first type of medium structure 300-1 on the first surface of the substrate is selected from: epoxy resin, polyimide, bismaleimide-triazine, build-up insulating film, polyphenyl ether, polypropylene, polymethyl acrylate, a combination of the above materials or other suitable insulating materials; these materials have high mechanical strength, high modulus, good thermal stability and high adhesion to various substrates and metals, can provide good support for the first heavy wiring structure 200, and the specific material selection is not limited herein. The bottom of the first type of medium structure 300-1 on the first surface of the substrate covers and closely contacts the first surface of the substrate 100, and completely covers the side surface of the first heavy wiring structure 200, which can play an insulating and protective role for the first heavy wiring structure 200, avoiding the risk of potential short circuit or signal leakage of the first heavy wiring structure 200.

[0088] Step S13: growing a second type of medium structure 400-1 on the first surface of the substrate 100, the side surface of the second type of medium structure 400-1 on the first surface of the substrate directly contacting the first type of medium structure 300-1 on the first surface of the substrate, and one second type of medium structure 400-1 on the first surface of the substrate being arranged between every two first heavy wiring structures 200. Please refer to Figure 9 , Figure 9To perform the step S13 after the formation of the package structure. The bottom of the second type of medium structure 400-1 of the first surface of the substrate covers and is in close contact with the first surface of the substrate 100, is formed between every two first heavy wiring structures 200, and its side surface is in direct contact with the first type of medium structure 300-1 of the first surface of the substrate, both of which completely fill the gap between the two adjacent first heavy wiring structures 200.

[0089] The material of the first type of medium structure 300-1 of the first surface of the substrate and the material of the second type of medium structure 400-1 of the first surface of the substrate are different, and the ratio of the dielectric constant of the material of the first type of medium structure 300-1 of the first surface of the substrate to the dielectric constant of the material of the second type of medium structure 400-1 of the first surface of the substrate is in the range of 1.3-2. The second type of medium structure 400-1 of the first surface of the substrate is selected from fluorine-based low-k medium materials. The fluorine-based low-k medium material has very low dielectric constant (about 2.3) and almost negligible dielectric loss factor (usually below 0.01), which is arranged between the two adjacent first heavy wiring structures 200 and in close contact with the first type of medium structure 300-1 of the first surface of the substrate, which can reduce the interconnection parasitic capacitance and reduce signal crosstalk. The second type of medium structure 400-1 of the first surface of the substrate can be CYTOP, PTFE or other fluorine-based low-k medium material, which is not limited in the present application.

[0090] In the present embodiment, by arranging the second type of medium structure 400-1 of the first surface of the substrate between the two adjacent first heavy wiring structures 200 and in direct contact with the first type of medium structure 300-1 of the first surface of the substrate, the dielectric constant of the material of the second type of medium structure 400-1 of the first surface of the substrate is lower than that of the material of the first type of medium structure 300-1 of the first surface of the substrate, replacing the traditional high dielectric constant material, so that the package structure provided by the present application can be applied in high frequency band, the parasitic capacitance between the lines is reduced, and signal crosstalk and delay are avoided; and the dielectric loss can be greatly reduced, the high frequency signal is prevented from producing serious signal attenuation, and the integrity of the high frequency signal is improved; at the same time, the ratio of the dielectric constant of the material of the first type of medium structure 300-1 of the first surface of the substrate to the dielectric constant of the material of the second type of medium structure 400-1 of the first surface of the substrate is in the range of 1.3-2, if the ratio is too small, for example, the ratio of the two is equal to 1, which means that the dielectric constants of the two materials are too close, and the function of reducing loss cannot be realized; if the ratio is too large, for example, the ratio of the two is greater than 2, which means that the stiffness of the low dielectric constant material may be too poor, and the reliability requirement of the package structure cannot be met.

[0091] In one embodiment, the step of forming the first redistribution structure 200 comprises:

[0092] Step S101: growing a first metal structure 201 on the first surface of the substrate 100, the first metal structure 201 is spaced apart on the first surface of the substrate 100. Please refer to Figure 4 , Figure 4 For the package structure formed after the step S101 is completed, first, a continuous seed layer is formed on the first surface of the substrate 100 by deposition technology, and then a photoresist is coated on the seed layer by photolithography technology and exposed and developed to define the required pattern window; then the metal is selectively grown in the patterned window by electroplating process to form the first metal structure 201, and finally the first metal structure 201 is spaced apart on the first surface of the substrate 100.

[0093] Step S102: growing a second metal structure 202 on the top of the first metal structure 201, the side surface of the second metal structure 202 is covered by the first type of medium structure 300-1 of the first surface of the substrate. The second metal structure 202 is grown by electroplating technology on the first metal structure 201, the bottom of the second metal structure 202 is in close contact with the top of the first metal structure 201, and the top of the first metal structure 201 is completely covered, the first metal structure 201 and the second metal structure 202 together constitute the complete first redistribution structure 200.

[0094] In one embodiment, the step of forming the first type of medium structure 300-1 of the first surface of the substrate comprises:

[0095] Step S103: growing a first medium structure 301 on the first surface of the substrate 100, the first medium structure 301 covers the first metal structure 201, and etches a first cavity and a second cavity on the top of the first metal structure 201 and between two adjacent first metal structures 201 respectively, the etching depth of the second cavity is greater than that of the first cavity. Please refer to Figure 5 , Figure 5To perform the package structure formed after the step S103, first, a first dielectric structure 301 is grown on the substrate surface where the first metal structure 201 has been formed by spin coating, spraying or deposition process, etc. The first dielectric structure 301 completely covers the first metal structure 201, fills the gap between two adjacent first metal structures 201 and covers the top surface thereof, forming a continuous insulating layer. Then, a pattern is defined on the first dielectric structure 301 by a photolithography process. Specifically, a part is located on the top of the first metal structure 201, i.e. the position of the first cavity, and another part is located between two adjacent first metal structures 201, i.e. the position of the second cavity. Then, the top of the first metal structure 201 and between two adjacent first metal structures 201 are etched to form the first cavity and the second cavity respectively by etching process. The shape of the second cavity can be rectangular, inverted trapezoidal, trapezoidal or any combination of the two. The etching depth of the first cavity is to expose the top surface of the first metal structure 201, which is to form the second metal structure 202 subsequently. The etching depth of the second cavity is to expose the first surface of the substrate 100, which is to form the second type of dielectric structure 400-1 to fill the first surface of the substrate subsequently. The step S103 is after the step S101, i.e. the step S103 is performed immediately after the step S101.

[0096] Step S104: A third dielectric structure 302 is grown on the top of the first dielectric structure 301, which covers the side surface of the second metal structure 202. The material of the third dielectric structure 302 is completely the same as that of the first dielectric structure 301, the bottom of which is in close contact with the top of the first dielectric structure 301, and the bottom completely covers the top of the first dielectric structure 301. The first dielectric structure 301 and the third dielectric structure 302 together constitute the final first type of dielectric structure 300-1 of the first surface of the substrate to form complete insulation support for the first redistribution structure 200.

[0097] In one embodiment, the step of forming the second type of dielectric structure 400-1 of the first surface of the substrate includes:

[0098] Step S105: A second dielectric structure 401 is grown on the first surface of the substrate 100, and the second dielectric structure 401 fills the second cavity. Referring to Figure 6 , Figure 6To perform the step S104 after the package structure formed, the second medium structure 401 is filled in the second cavity etched in the step S103 by deposition process, the bottom of the second medium structure 401 completely covers the top of the first surface of the substrate 100 in the second cavity, the bottom of the second medium structure 401 is in close contact with the first surface of the substrate 100, and the side surface of the second medium structure 401 is in close contact with the side surface of the first medium structure 301 formed in the step S103. Wherein, the step S105 is after the step S103, that is, the step S105 is performed immediately after the step S103 is performed; and the step S105 is before the step S102, that is, the step S102 is performed immediately after the step S105 is performed; the step S104 is performed immediately after the step S102 is performed.

[0099] Step S106: growing a fourth medium structure 402 on the top of the second medium structure 401; the material of the fourth medium structure 402 is completely same as that of the second medium structure 401, the bottom of the fourth medium structure 402 is in close contact with the top of the second medium structure 401, and the bottom of the fourth medium structure 402 completely covers the top of the second medium structure 401, the second medium structure 401 and the fourth medium structure 402 together constitute the final second type medium structure 400-1 of the first surface of the substrate. Wherein, the step S106 is after the step S104, that is, the step S106 is performed immediately after the step S104 is performed. After the step S106 is performed, the complete package structure of the first surface of the substrate 100 can be obtained.

[0100] In one embodiment, after the step S13, further comprising:

[0101] Step S107: growing a composite plating layer 600 on the top of the first re-distribution structure 200, the side surface of the composite plating layer 600 is covered by the first type medium structure 300-1 of the first surface of the substrate. The composite plating layer 600 is formed on the top of the first re-distribution structure 200 by deposition process, the bottom of the composite plating layer completely covers the top of the first re-distribution structure 200, and is in close contact with the top of the first re-distribution structure 200, and the side surface of the composite plating layer 600 is completely covered by the first type medium structure 300-1 of the first surface of the substrate.

[0102] Step S108: covering the surface of the package structure formed on the first surface of the substrate 100 with a temporary bonding film. The temporary bonding film can be an adhesive material which can be detached by heating or laser irradiation.

[0103] Step S109: Thinning the second surface of the substrate 100. In this step, the second surface of the substrate can be thinned by grinding, polishing, chemical polishing, or other methods to reduce the thickness of the substrate 100. This application does not limit the methods used in this step.

[0104] Step S110: A second redistribution structure 500, a first type of dielectric structure 300-2 on the second surface of the substrate 100, a second type of dielectric structure 400-2 on the second surface of the substrate, and the composite plating layer 600 are sequentially formed on the second surface of the substrate 100 to form an encapsulation structure on the second surface of the substrate 100 that is consistent with the first surface of the substrate 100; in this step, the second surface of the substrate 100 is treated in the same way as the first surface of the substrate 100 to form an encapsulation structure that is completely consistent with the first surface of the substrate 100.

[0105] Step S111: Remove the temporary bonding film to form the complete encapsulation structure. The specific removal method can be based on the characteristics of the temporary bonding film, employing methods such as heat debonding or laser irradiation. Further cleaning processes can be used to completely remove the temporary bonding film. After removing the temporary bonding film, the final encapsulation structure is as follows: Figure 10 The complete packaging structure is shown.

[0106] The fabrication method of the packaging structure provided in this application can be applied to most of the process flow for wafer-level advanced packaging, with higher processing precision, thinner dimensions, and thinner packaging thickness. Furthermore, the packaging structure provided in this application can significantly reduce dielectric loss and signal transmission loss, achieving higher integrity of high-frequency signals. At the same time, the packaging structure provided in this application can achieve consistent packaging of the first surface and the second surface of the substrate 100, realizing synchronous response between the top and bottom.

[0107] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0108] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A packaging structure, the packaging structure comprising: Substrate (100); A first wiring structure (200) is spaced apart on the first surface of the substrate (100); A first type of dielectric structure (300-1) on the first surface of the substrate is formed on the first surface of the substrate (100) and covers the side surface of the first redistribution structure (200); Its characteristic is that it further includes: The second type of dielectric structure (400-1) on the first surface of the substrate is disposed at intervals on the first surface of the substrate (100), and its side is in direct contact with the first type of dielectric structure (300-1) on the first surface of the substrate. A second type of dielectric structure (400-1) on the first surface of the substrate is disposed between every two first redistribution structures (200). Wherein, the material of the first type of dielectric structure (300-1) on the first surface of the substrate is different from the material of the second type of dielectric structure (400-1) on the first surface of the substrate, and the ratio of the dielectric constant of the material of the first type of dielectric structure (300-1) on the first surface of the substrate to the dielectric constant of the material of the second type of dielectric structure (400-1) on the first surface of the substrate is in the range of 1.3 to 2.

2. The packaging structure according to claim 1, characterized in that, The second surface of the substrate (100) includes: A second wiring structure (500) is spaced apart on the second surface of the substrate (100); A first type of dielectric structure (300-2) on the second surface of the substrate is formed on the second surface of the substrate (100) and covers the side surface of the second redistribution structure (500); A second type of dielectric structure (400-2) on the second surface of the substrate is disposed at intervals on the second surface of the substrate (100), and its side is in direct contact with the first type of dielectric structure (300-2) on the second surface of the substrate. A second type of dielectric structure (400-2) on the second surface of the substrate is disposed between every two second redistribution structures (500).

3. The packaging structure according to claim 2, characterized in that, The first type of dielectric structure (300-1) on the first surface of the substrate and the first type of dielectric structure (300-2) on the second surface of the substrate are selected from: epoxy resin, polyimide, bismaleimide-triazine, layered insulating film, polyphenylene ether, polypropylene, polymethyl methacrylate or a combination of the above materials; The second type of dielectric structure (400-1) on the first surface of the substrate and the second type of dielectric structure (400-2) on the second surface of the substrate are selected from fluorine-based low-k dielectric materials.

4. The packaging structure according to claim 2, characterized in that, The cross-sectional shape of the second type of dielectric structure (400-1) on the first surface of the substrate and the second type of dielectric structure (400-2) on the second surface of the substrate is rectangular, inverted trapezoidal, regular trapezoidal or any combination of the two.

5. The packaging structure according to claim 2, characterized in that, The packaging structure also includes: a composite coating (600). The composite coating (600) is formed on the top of the first redistribution structure (200) and the second redistribution structure (500), and the side surface of the composite coating (600) is covered by a first type of dielectric structure (300-1) on the first surface of the substrate or a first type of dielectric structure (300-2) on the second surface of the substrate. Furthermore, the composite coating (600) is made of a material with a surface roughness of less than 50 nm.

6. A method for preparing a packaging structure, used to form the packaging structure according to any one of claims 1-5, characterized in that, The method for preparing the encapsulation structure includes the following steps: Step S11: A first redistribution structure (200) is grown on the first surface of the substrate (100), wherein the first redistribution structure (200) is spaced apart on the first surface of the substrate (100); Step S12: A first type of dielectric structure (300-1) of the first surface of the substrate (100) is grown on the first surface of the substrate, and the first type of dielectric structure (300-1) of the first surface of the substrate covers the side surface of the first redistribution structure (200); Step S13: A second type of dielectric structure (400-1) of the first surface of the substrate (100) is grown on the first surface of the substrate. The side of the second type of dielectric structure (400-1) of the first surface of the substrate is in direct contact with the first type of dielectric structure (300-1) of the first surface of the substrate, and a second type of dielectric structure (400-1) of the first surface of the substrate is provided between every two first redistribution structures (200). The material of the first type of dielectric structure (300-1) on the first surface of the substrate is different from the material of the second type of dielectric structure (400-1) on the first surface of the substrate, and the ratio of the dielectric constant of the material of the first type of dielectric structure (300-1) on the first surface of the substrate to the dielectric constant of the material of the second type of dielectric structure (400-1) on the first surface of the substrate is in the range of 1.3 to 2.

7. The method for preparing the packaging structure according to claim 6, characterized in that, The steps for forming the first rewiring structure (200) include: Step S101: A first metal structure (201) is grown on the first surface of the substrate (100), wherein the first metal structure (201) is disposed at intervals on the first surface of the substrate (100); Step S102: A second metal structure (202) is grown on top of the first metal structure (201), and the side surface of the second metal structure (202) is covered by a first type of dielectric structure (300-1) of the first surface of the substrate.

8. The method for preparing the packaging structure according to claim 7, characterized in that, The steps for forming the first type of dielectric structure (300-1) on the first surface of the substrate include: Step S103: A first dielectric structure (301) is grown on the first surface of the substrate (100), the first dielectric structure (301) covers the first metal structure (201), and a first cavity and a second cavity are formed on the top of the first metal structure (201) and between two adjacent first metal structures (201), respectively. The etching depth of the second cavity is greater than the etching depth of the first cavity. Step S104: A third dielectric structure (302) is grown on top of the first dielectric structure (301), the third dielectric structure (302) covering the side surface of the second metal structure (202).

9. The method for preparing the packaging structure according to claim 8, characterized in that, The steps for forming the second type of dielectric structure (400-1) on the first surface of the substrate include: Step S105: A second dielectric structure (401) is grown on the first surface of the substrate (100), and the second dielectric structure (401) fills the second cavity; Step S106: Grow a fourth medium structure (402) on top of the second medium structure (401).

10. The method for preparing the packaging structure according to claim 6, characterized in that, The process after step S13 also includes: Step S107: A composite coating (600) is grown on top of the first redistribution structure (200), the side surface of which is covered by a first type of dielectric structure (300-1) on the first surface of the substrate; Step S108: Cover the surface of the encapsulation structure formed on the first surface of the substrate (100) with a temporary bonding film; Step S109: Thin the second surface of the substrate (100); Step S110: A second redistribution structure (500), a first type of dielectric structure (300-2) on the second surface of the substrate (100), a second type of dielectric structure (400-2) on the second surface of the substrate, and the composite plating layer (600) are sequentially formed on the second surface of the substrate (100) to form an encapsulation structure consistent with the first surface on the second surface of the substrate (100); Step S111: Remove the temporary bonding film to form the complete encapsulation structure.

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