Electroless copper plating solution and method for preparing nano-twinned copper metal layer by electroless plating

Abstract

The present invention relates to an electroless copper plating solution and a method for preparing a nano-twinned copper metal layer by electroless plating using the same. The electroless copper plating solution is an aqueous solution prepared from a complexing agent, a copper ion source, a reducing agent, a stabilizer, and a crystal growth agent. Using the electroless copper plating solution, a nano-twinned copper metal layer can be successfully prepared by electroless plating. Compared with existing electroplating or magnetron sputtering technologies, the method of the present invention does not require additional current supply, has a wider flow field control range, and does not require additional wire power supply to the area to be plated, thereby improving process and production capacity control capabilities and reducing production costs.

Description

Technical Field

[0001] The present invention relates to a metal surface treatment technology, in particular to an electroless copper plating solution and a method for preparing a nano-twinned copper metal layer by electroless plating using the plating solution. Background Art

[0002] The recent rapid development of the semiconductor industry has led to a trend toward miniaturization of chips, resulting in a corresponding improvement in packaging technology. One of the key elements in chip-to-chip bonding is 3D integrated circuit (3D IC) packaging. 3D IC refers to the stacking and vertical integration of multiple chips in three dimensions. Microbumps made of copper-tin material serve as contacts between the chips. The metallurgical reactions of the copper-tin system continue to be studied, and these reactions form two intermetallic compounds: Cu6Sn5 and Cu3Sn.

[0003] Research indicates that using nano-twinned copper as a metal pad and creating micro-bumps with pure tin solder allows for a reflow temperature of 260°C to quickly form Cu3Sn contacts. Kirkendall voids are virtually eliminated in the Cu3Sn layer, while the columnar crystals of the nano-twinned copper are preserved. Research also indicates that nano-twinned copper has an electromigration lifetime over 10 times that of standard copper and excellent mechanical strength. Therefore, using nano-twinned copper and void-free Cu3Sn as contacts on copper pads holds considerable potential in 3DIC packaging.

[0004] Furthermore, to increase the number of I / Os per unit area, chip size is further reduced, and the contact pitch and solder ball diameter are also reduced. However, during the reflow process, problems such as bridging failures have been found to cause contact failure, leading to the development of a method that does not use solder balls and relies solely on copper layer bonding to form reliable contacts.

[0005] In the copper / copper bonding process, copper has a faster diffusion rate in the <1,1,1> direction. Therefore, nano-twinned copper with a preferred orientation can be used in both rapid bonding and low-temperature bonding to achieve the requirement of reducing the thermal budget. However, the existing nano-twinned copper must be prepared using electroplating technology or magnetron sputtering technology. The electroplating method must be combined with a certain flow field control to obtain nano-twinned copper with the preferred orientation (1,1,1). It also requires additional current supply and strict control of the flow field. It also requires the design of additional wires to supply power to the desired area. The required circuit design and equipment requirements all impose a burden on the process and cost.

[0006] Nano-twinned copper foil also exhibits excellent thermal stability, resulting in significantly higher strength than standard copper foil after annealing at 250°C. However, some studies have used copper alloys to achieve this strength improvement, but this also increases electrical resistance. Nano-twinned copper foil, in addition to maintaining copper's excellent electrical conductivity, also enhances strength through its twin-crystal structure. Furthermore, when used in lithium-ion batteries, nano-twinned copper foil maintains a high-speed charge-discharge rate that is at least 20% higher than standard copper foil. Nano-twinned copper foil, with its excellent mechanical properties, high thermal stability, and high electrical conductivity, holds immense potential for the electric vehicle industry. However, its production remains limited by the hardware and in-line design required for electroplating. Summary of the Invention

[0007] In view of this, the main purpose of the present invention is to provide an electroless copper plating solution and a method for preparing a nano-twinned copper metal layer by electroless plating using the plating solution, so as to solve the technical problems that the current method of preparing nano-twinned copper requires additional current and strict control of the flow field, and requires the design of additional wires to supply power to the area to be plated, thereby reducing the difficulties and cost requirements in process control and equipment requirements.

[0008] To achieve the above-mentioned object, the present invention provides an electroless copper plating solution for preparing a nano-twinned copper metal layer by electroless plating. The electroless copper plating solution comprises:

[0009] 0.1-30 wt% of a complexing agent;

[0010] 0.01-5 wt % of a copper ion source;

[0011] 0.01-5 wt% of a reducing agent;

[0012] 0.00001-0.1% by weight of a stabilizer;

[0013] 0.0001-0.1 wt% of a crystal growth agent; and

[0014] The rest is water.

[0015] In addition, the present invention also provides a method for preparing a nano-twinned copper metal layer by electroless plating, the steps of which include:

[0016] Prepare the electroless copper plating solution and adjust the pH value of the electroless copper plating solution to 8-14;

[0017] Performing pre-treatment on the substrate; and

[0018] The electroless copper plating solution is used to deposit a nano-twinned copper metal layer on the pre-treated substrate.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The special formula of the electroless copper plating solution provided by the present invention can realize the successful manufacture of nano twinned copper metal layers by electroless plating technology.

[0021] The electroless plating method for preparing a nano-twinned copper metal layer provided by the present invention does not use electroplating or magnetron sputtering technology, so it can be used in semiconductor packaging processes and has the advantages of not requiring additional power supply, low hardware requirements and excellent circuit design.

[0022] The following is a detailed description with reference to specific embodiments to facilitate understanding of the objectives, technical content, features, and technical effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG. 1 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Example 1 of the present invention.

[0024] Figure 2 FIG. 4 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Comparative Example 1.

[0025] Figure 3 FIG. 1 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Example 2 of the present invention.

[0026] Figure 4 FIG. 4 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Comparative Example 2.

[0027] Figure 5 FIG. 1 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Example 3 of the present invention.

[0028] Figure 6 FIG. 4 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Comparative Example 3.

[0029] Figure 7 FIG. 4 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Example 4 of the present invention.

[0030] Figure 8 FIG. 4 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Comparative Example 4.

[0031] Figures 9-11 They are focused ion beam tomography images of copper layers prepared using the electroless copper plating solutions of Examples 5 to 7 of the present invention, respectively.

[0032] Figure 12 FIG. 5 is a focused ion beam tomography image of a copper layer prepared using the electroless copper plating solution of Comparative Example 5.

[0033] Figure 13The figure is a focused ion beam tomography image of a copper layer prepared on an insulating resin substrate using the electroless copper plating solution of the present invention.

[0034] Figure 14 The figure is a focused ion beam tomography image of a copper layer produced on a metal substrate using the electroless copper plating solution of the present invention.

[0035] Figure 15 The figure is a focused ion beam tomography image of a copper layer prepared by using the electroless copper plating solution of the present invention at a stirring speed of 300 rpm.

[0036] Figure 16 The figure is a focused ion beam tomography image of a copper layer prepared by using the electroless copper plating solution of the present invention without stirring.

[0037] Figure 17 The figure is an XRD spectrum of a copper layer prepared by using the electroless copper plating solution of the present invention before baking.

[0038] Figure 18 The present invention provides an XRD pattern of a copper layer prepared by using the electroless copper plating solution of the present invention and subjected to high-temperature baking. DETAILED DESCRIPTION

[0039] The present invention provides an electroless copper plating solution comprising the following components, in percentage by weight: 0.1-30% by weight of a complexing agent, 0.01-5% by weight of a copper ion source, 0.01-5% by weight of a reducing agent, 0.00001-0.1% by weight of a stabilizer, 0.0001-0.1% by weight of a crystal growth agent, and the remainder being water. A pH adjuster may be added to the electroless copper plating solution, the amount of the pH adjuster being such that the pH value of the electroless copper plating solution is 8-14.

[0040] The complexing agent may be selected from at least one of aminocarboxylic acids, hydroxycarboxylic acids, and polycarboxylic acids. The aminocarboxylic acid may be selected from at least one of ethylenediaminetetraacetic acid (EDTA), N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (HEDTA), cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, triethylenetetraaminehexaacetic acid, ethylenediaminetetrapropionic acid, aminetriacetic acid, iminodiacetic acid, hydroxyethyliminodiacetic acid, iminodipropionic acid, 1,3-propylenediaminetetraacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, glycol ether diaminetetraacetic acid, m-phenylenediaminetetraacetic acid, diaminopropionic acid, glutamic acid, dicarboxymethylglutamic acid, ornithine, cysteine, S-carboxymethyl-L-cysteine, N,N-bis(2-hydroxyethyl)glutamic acid, (S,S)-ethylenediaminesuccinic acid, and salts thereof. The hydroxycarboxylic acid may be selected from at least one of tartaric acid, gluconic acid, citric acid, malic acid, glucoheptonic acid, glycolic acid, lactic acid, trihydroxybutyric acid, ascorbic acid, isocitric acid, hydroxymalonic acid, glyceric acid, hydroxybutyric acid, leucine, citramalic acid, salicylic acid, and salts thereof. The polycarboxylic acid may be selected from at least one of succinic acid, glutaric acid, malonic acid, adipic acid, oxalic acid, maleic acid, citraconic acid, itaconic acid, mesaconic acid, and salts thereof.

[0041] The copper ion source may include at least one of copper sulfate, copper halide, copper nitrate, copper oxide, copper acetate, copper pyrophosphate, copper tetrafluoroborate, copper alkyl sulfonate, copper aryl sulfonate, copper sulfamate, copper perchlorate, and copper gluconate.

[0042] The reducing agent may be selected from at least one of formaldehyde, dimethylamine borane (DMAB), glyoxylic acid, glyoxylate, pyrophosphite, hypophosphite, hypophosphate, borohydride, hydrazine and sugar.

[0043] The stabilizer can be selected from at least one of pyridine, bipyridine, phenanthroline, thiazole, thiadiazole, imidazole, diazole, pyrimidine, oxazole, isoxazole, triazole, tetrazole, thiourea, cyanide, thiocyanate, iodide, ethanolamine, hydroquinone, tocopherol, hexandol, caprolactam, polyethylene glycol, polypropylene glycol, polyethyleneimine, polyacrylamide, polyacrylic acid, ethylene oxide propylene oxide copolymer, polypropylene glycol-block-polyethylene glycol copolymer and their respective derivatives.

[0044] The crystal growth agent may be selected from alkyl sulfonates, alkyl quaternary ammonium salts, tetraalkyl phosphonium salts, iminium ions or polymers thereof, Burgess's reagent, piperidinium, isocyanide, benzimidazole sulfonates, mercaptobenzothiazole, mercaptotriazole, mercaptobenzoxazole, phenanthroline sulfonates, polydialkyldisulfide sulfonates, mercapto-hydrocarbyl-sulfonic acid salts, thiocarboxylic acid salts, mercaptocarboxylic acid salts, phenothiazine or derivatives thereof. Furthermore, the crystal growth agent may be selected from at least one of disodium 4,7-diphenyl-1,10-phenanthroline disulfonate, dithiobenzoic acid, sodium phenylbenzimidazole sulfonate, tetrakis(hydroxymethyl)phosphonium sulfate, and polyquaternium-7.

[0045] The pH adjuster may be selected from potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide or aqueous ammonia.

[0046] Furthermore, the present invention provides a method for preparing a nano-twinned copper metal layer by electroless plating using the above electroless copper plating solution, the specific steps of which are as follows:

[0047] Step 1) preparing the electroless copper plating solution and adjusting the pH value of the electroless copper plating solution to 8-14.

[0048] Step 2) Provide a substrate and perform pretreatment on the substrate. The substrate may be a non-conductive substrate, a non-conductive substrate with a copper surface or copper alloy circuitry, or a semiconductor substrate. The pretreatment process sequentially includes cleaning, micro-etching, and pickling the substrate.

[0049] Step 3) activating the pre-treated substrate with a catalyst.

[0050] Step 4) using an electroless copper plating solution to deposit a nano-twinned copper metal layer on the pre-treated and activated substrate.

[0051] In the above method, the non-conductive substrate may include but is not limited to a resin substrate, a ceramic substrate or a glass substrate; the semiconductor substrate may include but is not limited to a silicon substrate, a germanium substrate, a silicon germanium substrate, a silicon carbide substrate or a Group III-V semiconductor substrate, and the Group III-V semiconductor substrate may include but is not limited to a gallium arsenide substrate, a gallium nitride substrate, an indium phosphide substrate, an indium gallium phosphide substrate, an aluminum nitride substrate, an indium arsenide substrate, an aluminum arsenide substrate, an aluminum gallium arsenide substrate, an indium arsenide nitride substrate, an indium aluminum gallium arsenide substrate or an indium gallium arsenide phosphide substrate.

[0052] The present invention provides another method for preparing a nano-twinned copper metal layer by electroless plating using the above electroless copper plating solution, the specific steps of which are as follows:

[0053] Step 1) preparing the electroless copper plating solution and adjusting the pH value of the electroless copper plating solution to 8-14.

[0054] Step 2) providing a substrate and performing pre-treatment on the substrate; the substrate is a metal substrate. The pre-treatment process includes the step of pickling the substrate.

[0055] Step 3) using an electroless copper plating solution to deposit a nano-twinned copper metal layer on the pre-treated substrate.

[0056] Furthermore, to illustrate and verify the technical effects achieved by the electroless copper plating solution of the present invention, copper layers were produced using the electroless copper plating solution of the present invention (Examples 1 to 3) and conventional electroless copper plating solutions (Comparative Examples 1 to 3). The arrangement of the copper lattice in the resulting copper layers was analyzed and compared. In addition, the lattice structure of the electroless copper plating solution of the present invention on various substrates and flow fields was examined using focused ion beam tomography (FIB-SEM). Finally, X-ray diffraction analysis (XRD) was used to compare the structural orientation of the copper layers produced using the electroless copper plating solution of the present invention before and after high-temperature baking.

[0057] Electroless copper lattice comparison method:

[0058] An electroless copper plating solution to be observed was prepared and heated to 40-50°C. A pre-treated substrate with a catalyst to be plated was placed in the solution for 30-60 minutes. The surface was then rinsed with deionized water and dried in an oven at 90°C for 10 minutes. The arrangement of the copper lattice was then compared using FIB-SEM to verify that the composition of the electroless copper plating solution of the present invention could effectively form a nano-twinned copper metal layer.

[0059] Preparation method:

[0060] In the case of a non-conductive or semiconductor substrate, the substrate is subjected to surface metallization treatment in the following order: cleaning and degreasing (50°C, 5 minutes); water rinsing (room temperature, 1 minute); micro-etching (room temperature, 1 minute); water rinsing (room temperature, 1 minute); acid pickling (room temperature, 1 minute); water rinsing (room temperature, 1 minute); activation (room temperature, 1 minute); water rinsing (room temperature, 1 minute). Finally, electroless copper plating is performed. The process conditions are detailed below.

[0061] In the case of a metal substrate, the substrate is metallized in the following steps: cleaning and degreasing (50°C, 5 minutes); water rinsing (room temperature, 1 minute); acid cleaning (room temperature, 1 minute); and water rinsing (room temperature, 1 minute). Finally, electroless copper plating is performed. The process conditions are detailed below.

[0062] Example 1:

[0063] In this embodiment, the composition of the electroless copper plating solution is shown in Table 1. The pH of the electroless copper plating solution was adjusted to 12 with sodium hydroxide, and a 100×100 mm glass substrate that had been sputtered with copper was immersed in the plating solution for 30 minutes at a temperature of 45°C. A nano-twinned copper metal layer with an average thickness of 2 μm was obtained. The copper layer was subjected to FIB-SEM, which revealed a distinct layered and columnar structure, as shown in FIG. Figure 1 As shown. From the FIB-SEM image, it can be observed that the copper layer is the light-colored part in the image. Figure 1 The thickness of the copper layer is represented by d and will not be repeated below.

[0064] Table 1

[0065]

[0066]

[0067] Comparative Example 1:

[0068] In this comparative example, the composition of the electroless copper plating solution is shown in Table 2. Under the same conditions as in Example 1, pyrimidine and disodium bathophenanthroline disulfonate were removed from the electroless copper plating solution of Example 1. The resulting copper layer was tested, and the average copper thickness was 2.5 μm. The copper layer was observed by focused ion beam tomography, and no obvious crystal structure was produced. Figure 2 shown.

[0069] Table 2

[0070] composition Content (WT%) EDTA 3.0％ copper sulfate 1.0％ formaldehyde 0.3％ Sodium hydroxide 0.5％ Ethanolamine 0.1％ water 95％

[0071] Example 2:

[0072] In this embodiment, the composition of the electroless copper plating solution is shown in Table 3. The pH of the electroless copper plating solution was adjusted to 13 with sodium hydroxide, and a 50×50 mm copper foil substrate was immersed in the plating solution for 60 minutes at a plating temperature of 55°C. A nano-twinned copper metal layer with an average thickness of 4.5 μm was obtained. The copper layer was subjected to FIB-SEM to reveal a distinct layered and columnar structure, as shown in FIG. Figure 3 shown.

[0073] Table 3

[0074]

[0075]

[0076] Comparative Example 2:

[0077] In this comparative example, the composition of the electroless copper plating solution is shown in Table 4. Under the same conditions as in Example 2, dithiobenzoic acid was removed from the electroless copper plating solution of Example 2, and the resulting copper layer was tested. The average copper thickness was 5 μm. The copper layer was observed by focused ion beam tomography, and no obvious crystal structure was produced. Figure 4 shown.

[0078] Table 4

[0079] composition Content (WT%) Mesaconic acid 15.0％ copper sulfate 1.0％ formaldehyde 0.3％ Sodium hydroxide 0.5％ Polyethyleneimine 0.1％ water 95％

[0080] Example 3:

[0081] In this embodiment, the composition of the electroless copper plating solution is shown in Table 5. The pH of the electroless copper plating solution was adjusted to 12 with sodium hydroxide, and a 50×50 mm resin substrate was immersed in the plating solution for 60 minutes at a plating temperature of 60°C. A nano-twinned copper metal layer with an average thickness of 5 μm was obtained. Focused ion beam tomography of this copper layer revealed obvious layered and columnar structures, as shown in FIG. Figure 5 shown.

[0082] Table 5

[0083]

[0084]

[0085] Comparative Example 3:

[0086] In this comparative example, the composition of the electroless copper plating solution is shown in Table 6. Under the same conditions as in Example 3, pyrimidine and sodium phenylbenzimidazole sulfonate were removed from the electroless copper plating solution of Example 3, and the resulting copper layer was tested. The average copper thickness was 5.5 μm. The copper layer was observed by focused ion beam tomography, and no obvious crystal structure was produced. Figure 6 shown.

[0087] Table 6

[0088] composition Content (WT%) EDTA 3.0％ copper sulfate 1.0％ formaldehyde 0.3％ Sodium hydroxide 0.5％ Polyethylene glycol-1000 0.2％ water 95％

[0089] Example 4:

[0090] In this embodiment, the composition of the electroless copper plating solution is shown in Table 7. The pH of the electroless copper plating solution was adjusted to 12 with sodium hydroxide, and a 50×50 mm resin substrate was immersed in the plating solution for 60 minutes at a plating temperature of 45°C. A nano-twinned copper metal layer with an average thickness of 3.5 μm was obtained. Focused ion beam tomography of this copper layer revealed obvious layered and columnar structures, as shown in FIG. Figure 7 shown.

[0091] Table 7

[0092] composition Content (WT%) potassium sodium tartrate 3.0％ copper sulfate 1.0％ formaldehyde 0.3％ Sodium hydroxide 0.5％ Imidazole 0.1％ Tetrakis (hydroxymethyl)phosphonium sulfate 0.1％ water 95％

[0093] Comparative Example 4:

[0094] In this comparative example, the composition of the electroless copper plating solution is shown in Table 8. Under the same conditions as in Example 4, tetrakis(hydroxymethyl)phosphonium sulfate was removed from the electroless copper plating solution of Example 4, and the resulting copper layer was tested. The average copper thickness was 3.5 μm. The copper layer was observed by focused ion beam tomography, and no obvious crystal structure was produced. Figure 8 shown.

[0095] Table 8

[0096] composition Content (WT%) potassium sodium tartrate 5.0％ copper sulfate 1.0％ formaldehyde 0.3％ Sodium hydroxide 0.5％ Imidazole 0.1％ water 95％

[0097] Embodiment 5-7:

[0098] In Examples 5-7, the composition of the electroless copper plating solution is shown in Table 9, with the proportion of each component expressed in wt%. The pH of the electroless copper plating solution was adjusted to 10 with sodium hydroxide, and a 4-inch semiconductor substrate was immersed in the plating solution for 60 minutes at a temperature of 55°C. Depending on the concentration of polyquaternium-7, nano-twinned copper metal layers with average thicknesses of 4 μm, 5 μm, and 5.8 μm were prepared, respectively. Focused ion beam tomography of these copper layers revealed distinct layered and columnar structures, as shown in FIG. Figures 9-11 shown.

[0099] Table 9

[0100] composition Example 5 Example 6 Example 7 EDTA 3.0％ 3.0％ 3.0％ copper sulfate 1.0％ 1.0％ 1.0％ formaldehyde 0.3％ 0.3％ 0.3％ Sodium hydroxide 0.5％ 0.5％ 0.5％ Ethanolamine 0.1％ 0.1％ 0.1％ Thiadiazole dimercapto 0.001％ 0.001％ 0.001％ Polyquaternium-7 0.0001％ 0.001％ 0.1％ Average copper thickness 4μm 5μm 5.8μm

[0101] Comparative Example 5:

[0102] In this comparative example, the composition of the electroless copper plating solution is shown in Table 10. Under the same conditions as in Example 6, polyquaternium-7 was removed from the electroless copper plating solution of Example 6, and the resulting copper layer was tested. The average copper thickness was 4.5 μm. The copper layer was observed by focused ion beam tomography, and no obvious crystal structure was produced. Figure 12 shown.

[0103] Table 10

[0104]

[0105]

[0106] Observation of plating structure on different substrates:

[0107] like Figure 13 and Figure 14Figures 2 and 3 show copper layers produced using the electroless copper plating solution of the present invention on both insulating resin and metal substrates. Plating conditions included a 60-minute immersion period at a bath temperature of 50°C. The copper layers exhibit distinct lamellar and columnar structures. Therefore, the electroless copper plating solution of the present invention reproduces the nano-twinned copper lattice structure in copper layers produced on various substrates.

[0108] Observation of the plating structure under different flow fields:

[0109] like Figure 15 and Figure 16 The figures show copper layers produced by electroless copper plating using the electroless copper plating solution of the present invention at a stirring speed of 300 rpm and without stirring, respectively. Plating conditions included a 20-minute immersion and a bath temperature of 50°C. Both layers exhibit distinct lamellar and columnar structures. Therefore, the copper layers produced using the electroless copper plating solution of the present invention at different stirring speeds can all reproduce the nano-twinned copper lattice structure.

[0110] XRD analysis of copper layer structure before and after high temperature baking:

[0111] like Figure 17 and Figure 18 As shown, the XRD patterns of the copper layer prepared by the electroless copper plating solution of the present invention before and after high-temperature baking are respectively shown. The baking conditions are a baking temperature of 150°C and a baking time of 30 minutes. The XRD results show that there is almost no difference in the structural direction after baking. The obvious diffraction peak of the Cu (1,1,1) crystal plane can be clearly observed, and the Cu (1,1,1) ratio in the copper layer is close to 100%, which meets the definition of nano-twinned copper with a ratio greater than 96%.

[0112] In summary, the electroless copper plating solution and the method for preparing a nano-twinned copper metal layer using the electroless plating solution disclosed in the present invention successfully achieve the goal of producing a nano-twinned copper metal layer using electroless plating technology through the special formulation of the electroless copper plating solution. Because it does not use electroplating or magnetron sputtering technology, it does not require additional current supply, the flow field control range is wider, and no additional wires are required to power the desired plating area. Therefore, it has the advantages of lower hardware requirements and better circuit design. As a result, hardware costs, design costs, and process costs can be significantly reduced.

[0113] The electroless copper plating solution and the method for preparing a nano-twinned copper metal layer using the electroless plating solution disclosed in the present invention enable the electroless preparation of nano-twinned copper with a preferred orientation of (1,1,1). This nano-twinned copper exhibits excellent mechanical properties, high thermal stability, and high conductivity, while also resisting electron migration and reducing Kirkendall voids. With the increasing miniaturization of chips in the future, the present invention can be applied to related processes such as semiconductor packaging and battery copper foil applications. By eliminating the circuit design required for electroplating, it can enhance package bonding strength, reduce voids and signal transmission issues, and increase the number of I / Os that can be accommodated per unit area, effectively improving the process and reducing costs.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. Therefore, any equivalent changes or modifications made according to the features and spirit described in the scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. An electroless copper plating solution for preparing a nano-twinned copper metal layer by electroless plating, characterized in that: The electroless copper plating solution comprises: a) 0.1-30 wt % of a complexing agent; b) 0.01-5 wt % of a copper ion source; c) 0.01-5% by weight of a reducing agent; d) 0.00001-0.1% by weight of a stabilizer; e) 0.0001-0.1 wt% of a crystal growth agent; and f) the remainder is water; The crystal growth agent is selected from at least one of disodium 4,7-diphenyl-1,10-phenanthroline disulfonate, dithiobenzoic acid, sodium phenylbenzimidazole sulfonate, tetrakis(hydroxymethyl)phosphonium sulfate and polyquaternium-7.

2. The electroless copper plating solution according to claim 1, wherein The complexing agent is selected from at least one of aminocarboxylic acid, hydroxycarboxylic acid and polycarboxylic acid.

3. The electroless copper plating solution according to claim 2, wherein The aminocarboxylic acid is at least one selected from the group consisting of ethylenediaminetetraacetic acid, N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid, cyclohexanediaminetetraacetic acid, diethylenetriaminepentaacetic acid, hydroxyethylethylenediaminetriacetic acid, triethylenetetraaminehexaacetic acid, ethylenediaminetetrapropionic acid, aminetriacetic acid, iminodiacetic acid, hydroxyethyliminodiacetic acid, iminodipropionic acid, 1,3-propylenediaminetetraacetic acid, 1,3-diamino-2-hydroxypropanetetraacetic acid, glycol ether diaminetetraacetic acid, m-phenylenediaminetetraacetic acid, diaminopropionic acid, glutamic acid, dicarboxymethylglutamic acid, ornithine, cysteine, S-carboxymethyl-L-cysteine, N,N-bis(2-hydroxyethyl)glutamic acid, (S,S)-ethylenediaminesuccinic acid, and salts thereof.

4. The electroless copper plating solution according to claim 2, wherein The hydroxycarboxylic acid is selected from at least one of tartaric acid, gluconic acid, citric acid, malic acid, glucoheptonic acid, glycolic acid, lactic acid, trihydroxybutyric acid, ascorbic acid, isocitric acid, hydroxymalonic acid, glyceric acid, hydroxybutyric acid, citramalic acid, salicylic acid and salts thereof.

5. The electroless copper plating solution according to claim 2, wherein The polycarboxylic acid is at least one selected from succinic acid, glutaric acid, malonic acid, adipic acid, oxalic acid, maleic acid, citraconic acid, itaconic acid, mesaconic acid and salts thereof.

6. The electroless copper plating solution according to claim 1, wherein The copper ion source includes at least one of copper sulfate, copper halide, copper nitrate, copper oxide, copper acetate, copper pyrophosphate, copper tetrafluoroborate, copper alkyl sulfonate, copper aryl sulfonate, copper sulfamate, copper perchlorate and copper gluconate.

7. The electroless copper plating solution according to claim 1, wherein The reducing agent is selected from at least one of formaldehyde, dimethylamine borane (DMAB), glyoxylic acid, glyoxylate, pyrophosphite, hypophosphite, hypophosphate, borohydride, hydrazine and sugar.

8. The electroless copper plating solution according to claim 1, wherein The stabilizer is selected from at least one of pyridine, phenanthroline, thiazole, thiadiazole, imidazole, pyrimidine, oxazole, isoxazole, triazole, tetrazole, thiourea, cyanide, thiocyanate, iodide, ethanolamine, hydroquinone, tocopherol, hexandol, caprolactam, polyethylene glycol, polypropylene glycol, polyethyleneimine, polyacrylic acid, ethylene oxide propylene oxide copolymer and polypropylene glycol-block-polyethylene glycol copolymer.

9. The electroless copper plating solution according to claim 1, wherein The composition of the electroless copper plating solution further includes a pH adjuster for adjusting the pH value of the electroless copper plating solution to 8-14.

10. The electroless copper plating solution according to claim 9, wherein The pH adjuster is selected from potassium hydroxide, sodium hydroxide, lithium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide or ammonia water.

11. A method for preparing a nano-twinned copper metal layer by electroless plating, characterized in that: include: 1) preparing the electroless copper plating solution as claimed in claim 1, and adjusting the pH value of the electroless copper plating solution to 8-14; 2) performing pre-processing on a substrate; and 3) Depositing a nano-twinned copper metal layer on the pre-treated substrate using the electroless copper plating solution.

12. The method for preparing a nano-twinned copper metal layer by electroless plating according to claim 11, wherein: The substrate is selected from a non-conductive substrate or a semiconductor substrate.

13. The method for preparing a nano-twinned copper metal layer by electroless plating according to claim 12, wherein: The non-conductive substrate is a resin substrate, a ceramic substrate or a glass substrate.

14. The method for preparing a nano-twinned copper metal layer by electroless plating according to claim 12, wherein: The semiconductor substrate is a silicon substrate, a germanium substrate, a silicon germanium substrate, a silicon carbide substrate, a gallium arsenide substrate, a gallium nitride substrate, an indium phosphide substrate, an indium gallium phosphide substrate, an aluminum nitride substrate, an indium arsenide substrate, an aluminum arsenide substrate, an aluminum gallium arsenide substrate, an indium arsenide nitride substrate, an indium aluminum gallium arsenide substrate or an indium gallium arsenide phosphide substrate.

15. The method for preparing a nano-twinned copper metal layer by electroless plating according to claim 12, wherein: Step 2) includes the steps of cleaning, micro-etching and pickling the substrate in sequence.

16. The method for preparing a nano-twinned copper metal layer by electroless plating according to claim 13, wherein: After step 2), the process includes a step of activating the substrate with a catalyst.

17. The method for preparing a nano-twinned copper metal layer by electroless plating according to claim 11, wherein: The substrate is a metal substrate.

18. The method for preparing a nano-twinned copper metal layer by electroless plating according to claim 17, wherein: Step 2) includes the step of pickling the substrate.

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