Additive for plating solution and preparation method therefor, and nanotwinned copper electroplating solution and use thereof

Abstract

The present application provides an additive for a plating solution and a preparation method therefor, and a nanotwinned copper electroplating solution and the use thereof. The preparation method comprises: reacting a protein additive with an aldehyde compound, so as to obtain the additive for a plating solution, which additive has a good stability and a good twinning promoting effect, and does not affect the filling effect of a pattern additive. The nanotwinned copper electroplating solution containing the additive for a plating solution has a good stability, is free of the phenomena of turbidity, precipitation, discoloration, etc., after long-time storage, and has a stable pH value, stable appearance and substantially prolonged shelf life and service life, thereby widening the operation process window of electroplating and making it possible to obtain a nanotwinned copper plating having good performance.

Description

A plating solution additive and a preparation method thereof, a nano-twin copper electroplating solution and application thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of integrated circuits and metal manufacturing, for example, a plating solution additive and a preparation method thereof, a nano-twin copper electroplating solution and application thereof. BACKGROUND

[0002] Electroplating copper technology is an indispensable key technology in modern microelectronic manufacturing and is widely used in integrated circuits, device packaging, microelectromechanical systems, and circuit boards. High-end electroplating copper requires materials to have good ductility, low impurity content, low internal stress, heat treatment stability, and excellent mechanical and electrical properties such as electromigration resistance. Nano-twin copper has high electrical conductivity, high mechanical strength, excellent electromigration resistance, and stability due to its special microstructure, and has broad application prospects in advanced wafer-level packaging technologies such as bump under-bonding, wafer rewiring, and copper pillar bumping. It is considered to be a key iteration technology for the next generation of high-performance electronic interconnection electroplating copper.

[0003] The microstructure of nano-twin copper, its application, and its preparation method have been a research hotspot in recent years. For example, CN114232037A discloses a nano-twin copper foil, which has the same (111) and (220) texture strength as a standard copper powder sample but weaker (200) texture, thereby improving the strength of the copper foil. The nano-twin copper foil is deposited using a direct current electrolytic deposition technology, and the electrolyte used includes 200-350 g / L of copper sulfate pentahydrate, 10-120 g / L of H2SO4, 2-30 mg / L of gelatin, 10-100 mg / L of HCl, 1-20 mg / L of collagen, 1-5 mg / L of polydithiodipropyl sulfonic acid sodium, 10-500 mg / L of disodium ethylenediaminetetraacetate, and the balance is water. CN116334702A discloses a nano-twin copper thin film material with highly oriented (220) texture, which is prepared by an electrodeposition process. The plating solution used includes 30-150 g / L of copper sulfate, 10-20 mL / L of strong acid, 30-60 ppm of sodium chloride, 10-80 ppm of protein, and the balance is water. CN114086224A discloses a twin copper material and a preparation method thereof. The plating solution in the preparation method contains copper ions, sulfuric acid, chloride ions, an additive, and water. The additive includes an inhibitor and an auxiliary agent, wherein the inhibitor is gelatin and the auxiliary agent is an organic sulfonate salt. The prepared twin copper material has a (110) crystal plane preferred orientation.

[0004] The current nano-twin copper plating solution is mainly composed of copper ions, sulfuric acid, chloride ions and additives. Gelatin is a common plating additive. Adding a small amount of gelatin into the plating solution can reduce the roughness of the plating layer and make the plating layer bright. At the same time, gelatin is also a twin promoting agent for direct current deposition of nano-twin copper, which helps to obtain a high-density nano-twin copper plating layer. However, the stability of the current twin copper plating solution is generally poor, and the process window is narrow, which limits its industrial production. This has something to do with the fact that the twin promoting agent is prone to decomposition. Gelatin has a degradation behavior in aqueous solution. It continuously absorbs hydrogen ions in the solution, and the pH continuously rises. Even turbidity and precipitation occur, which makes the shelf life of the additive shorter. On the other hand, during the standing and electrification process of the plating solution during direct current deposition, gelatin will also decompose and consume. The formation of twin structure is extremely sensitive to the change of gelatin concentration, resulting in poor stability of nano-twin copper preparation and problems such as decrease of twin density. Therefore, it is urgent to develop a more stable twin promoting agent and twin copper plating solution to broaden the process window of twin copper preparation and obtain a twin copper with better performance.

[0005] SUMMARY

[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0007] The present application provides a plating solution additive and a preparation method thereof, a nano-twin copper plating solution and an application. The plating solution additive is obtained by reacting a protein additive with an aldehyde compound, has excellent stability and twin promoting effect, thereby significantly improving the stability and service life of the nano-twin copper plating solution containing it, broadening the process window of twin copper preparation, and being able to obtain a nano-twin copper plating layer with excellent performance.

[0008] In a first aspect, the present application provides a preparation method of a plating solution additive, which comprises: reacting a protein additive with an aldehyde compound to obtain the plating solution additive.

[0009] The present application research found that the stability of the protein additive is poor, mainly because the molecular structure of the protein additive contains a large number of amino groups (mainly primary amine group -NH2, also including secondary amine group -NH-, etc.), which can react with water in aqueous solution and plating solution to generate amine radical (-NH3 + ) and hydroxyl radical (OH -), leading to the continuous increase of pH value of the electroplating solution and the deterioration of stability. In the application, the aldehyde compound is used to chemically modify the protein additive. The amino groups in the protein additive react with the aldehyde groups to form imine bonds, so that the number of free amino groups is reduced, and the hydrolysis of the free amino groups in the aqueous solution (electroplating solution) is inhibited. Moreover, the imine bonds can be hydrolyzed in the aqueous solution, and further crosslinking occurs, so that a large number of amino groups on the protein additive are crosslinked to finally form a stable modified product. Therefore, the plating solution additive prepared in the application has significantly improved stability, and can also play an excellent twin crystal promoting role, so that the nano twin crystal copper electroplating solution containing the same has excellent storage and use stability, and the working life thereof is prolonged, thereby widening the operation process window of electroplating, and an excellent nano twin crystal copper plating layer can be prepared.

[0010] The following is an optional technical scheme of the application, but is not a limitation on the technical scheme provided by the application. Through the following optional technical scheme, the purpose and beneficial effects of the application can be better achieved and realized.

[0011] In an embodiment, the protein additive comprises any one or a combination of at least two of gelatin, collagen and polypeptide, and further optionally gelatin.

[0012] In an embodiment, the number average molecular weight of the protein additive is 1000-100000, for example, can be 1500, 2000, 3000, 4000, 5000, 6000, 8000, 10000, 12000, 15000, 18000, 20000, 25000, 30000, 35000, 40000, 450000, 50000, 60000, 70000, 80000 or 90000, and specific point values between the above point values. Due to the consideration of brevity and simplicity, the specific point values included in the range are not listed herein, and further optionally 8000-22000.

[0013] In an embodiment, the aldehyde compound comprises aliphatic aldehyde and / or aromatic aldehyde.

[0014] In the application, the number of aldehyde groups in the aldehyde compound is ≥1, for example, can be 1, 2, 3, etc.

[0015] In an embodiment, the aldehyde compound has a structure as shown in formula I:

[0016] In formula I, R1 is selected from any one of substituted or unsubstituted C1-C18 straight chain or branched alkyl, substituted or unsubstituted C2-C18 alkenyl, and substituted or unsubstituted C6-C18 aryl.

[0017] The C1-C18 linear or branched alkyl group can be a linear or branched alkyl group of C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, and exemplary includes but is not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-methylbutyl, n-pentyl, isopentyl, neopentyl, n-hexyl, neohexyl, 2-ethylhexyl, n-octyl, n-heptyl, n-nonyl, n-decyl, and the like.

[0018] The C2-C18 alkenyl group can be a linear or branched alkenyl group of C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, and includes at least one C=C, and exemplary includes but is not limited to vinyl, propenyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, butadienyl, pentadienyl, and the like.

[0019] The C6-C18 aryl group can be a monocyclic or fused ring aryl group of C6, C9, C10, C12, C13, C14, C16, C18, and exemplary includes but is not limited to phenyl, biphenyl, terphenyl, naphthyl, anthryl, phenanthryl, and the like.

[0020] The substituents in R1are each independently selected from at least one of C1-C6 (e.g., C1, C2, C3, C4, C5, C6) linear or branched alkyl, aldehyde group (-CHO).

[0021] In one embodiment, the aldehyde compound includes any one or a combination of at least two of formaldehyde, acetaldehyde, propionaldehyde, glutaraldehyde, acrolein, benzaldehyde.

[0022] In one embodiment, the mass ratio of the aldehyde compound to the protein additive is (1-30):1, for example, can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 12:1, 14:1, 15:1, 16:1, 18:1, 20:1, 22:1, 25:1, 28:1, or 30:1, and the like, and further optionally (1.2-20):1.

[0023] In one embodiment, the reaction is carried out in the presence of water.

[0024] In one embodiment, the preparation method includes mixing a protein additive, an aldehyde compound, and water to obtain a mixed solution; and the mixed solution is reacted to obtain the plating solution additive.

[0025] In one embodiment, the concentration of the aldehyde compound in the mixture is 0.1-15 g / L, for example, it can be 0.2 g / L, 0.5 g / L, 0.8 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, 9.5 g / L, 10 g / L, 11 g / L, 12 g / L, 13 g / L, or 14 g / L, and specific point values between the above point values. Due to the limitation of the length and for the sake of simplicity, the specific point values included in the range are not listed herein.

[0026] In one embodiment, the reaction is carried out under stirring.

[0027] In one embodiment, the pH value of the reaction is 7-11, for example, it can be 7.2, 7.5, 7.8, 8, 8.2, 8.5, 8.8, 9, 9.2, 9.5, 9.8, 10, 10.2, 10.5, or 10.8, and specific point values between the above point values. Due to the limitation of the length and for the sake of simplicity, the specific point values included in the range are not listed herein.

[0028] As an optional technical solution of the present application, by adjusting the conditions of the mixture / reaction to 7 < pH value ≤ 11, the reaction of the amino group and the aldehyde group and the formation of the imine bond can be promoted under alkaline conditions, so that the reaction rate is faster.

[0029] In one embodiment, the temperature of the reaction is 30-50°C, for example, it can be 32°C, 35°C, 38°C, 40°C, 42°C, 45°C, or 48°C, and specific point values between the above point values. Due to the limitation of the length and for the sake of simplicity, the specific point values included in the range are not listed herein.

[0030] In one embodiment, the reaction time is 5 min-12 h, for example, it can be 10 min, 20 min, 30 min, 40 min, 50 min, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h, 9.5 h, 10 h, 10.5 h, 11 h, or 11.5 h, and specific point values between the above point values. Due to the limitation of the length and for the sake of simplicity, the specific point values included in the range are not listed herein.

[0031] In one embodiment, the reaction further comprises a purification step after the reaction is completed.

[0032] In one embodiment, the purification method comprises filtration and / or dialysis.

[0033] In one embodiment, the dialysis bag used for dialysis has a molecular weight cut-off of 1000-60000, for example, it can be 2000, 3000, 5000, 8000, 10000, 12000, 15000, 18000, 20000, 22000, 25000, 30000, 35000, 40000, 45000, 50000 or 55000, and specific point values between the above point values, for the sake of brevity and simplicity, the specific point values included in the range are not listed in this application, and further optionally 2000-50000.

[0034] In order to avoid excessive cross-linking of the reaction, the generation of products with too large molecular weight, resulting in poor solubility in water, affecting the transparency of the electroplating solution containing it, as an optional technical solution of the present application, the method of dialysis is used for separation and purification, the product with too large molecular weight is removed, the clear liquid obtained by dialysis is collected and concentrated (evaporation concentration), and the electroplating solution additive with appropriate molecular weight is obtained.

[0035] In one embodiment, the number of water changes in the dialysis is 1-5 times, for example, it can be 2 times, 3 times, 4 times, 5 times.

[0036] In one embodiment, the interval time of each water change in the dialysis is 6-12h, for example, it can be 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h or 11.5h, and specific point values between the above point values, for the sake of brevity and simplicity, the specific point values included in the range are not listed in this application.

[0037] In one embodiment, the number of water changes in the dialysis is 1-5 times, for example, it can be 2 times, 3 times, 4 times, 5 times.

[0038] In one embodiment, the number of water changes in the dialysis is 1-5 times, for example, it can be 2 times, 3 times, 4 times, 5 times.

[0039] In one embodiment, the number of water changes in the dialysis is 1-5 times, for example, it can be 2 times, 3 times, 4 times, 5 times.

[0040] The nano-twin copper electroplating solution provided in the application adopts the plating solution additive prepared by the first aspect as a twin promoting agent, so that it has excellent stability, does not appear turbidity, precipitation and discoloration and other phenomena after long time storage, the pH remains stable, the shelf life and service life are significantly prolonged, and the operation process window of electroplating is widened. At the same time, the plating solution additive has excellent twin promoting effect, and does not affect the filling effect of other pattern additives such as leveling agent, accelerator and inhibitor. The twin copper plating layer prepared by using the nano-twin copper electroplating solution has controllable organization morphology and excellent organization consistency, and the twin copper has the performance advantages of high strength, high conductivity, high electromigration resistance, oxidation resistance and thermal stability.

[0041] In one embodiment, the concentration of copper ions in the nano-twin copper electroplating solution is 20-60 g / L, for example, it can be 22 g / L, 25 g / L, 28 g / L, 30 g / L, 32 g / L, 35 g / L, 38 g / L, 40 g / L, 42 g / L, 45 g / L, 48 g / L, 50 g / L, 52 g / L, 55 g / L or 58 g / L, and specific point values between the above point values. Due to the limitation of length and for the sake of simplicity, the specific point values included in the range are not listed in this application.

[0042] In this application, the copper ions in the nano-twin copper electroplating solution are provided by copper salt, and the copper salt includes any one or a combination of at least two of copper sulfate pentahydrate (CuSO4·5H2O), copper sulfate, copper sulfamate and copper methyl sulfonate.

[0043] In one embodiment, the concentration of sulfuric acid in the nano-twin copper electroplating solution is 20-120 g / L, for example, it can be 30 g / L, 40 g / L, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L or 110 g / L, and specific point values between the above point values. Due to the limitation of length and for the sake of simplicity, the specific point values included in the range are not listed in this application.

[0044] For example, in the nano-twin copper electroplating solution, sulfuric acid is introduced into the electroplating solution by diluting 96-98% (for example, 96.5%, 97%, 97.5% and the like) concentrated sulfuric acid.

[0045] In one embodiment, the mass concentration of chloride ions in the nano-twin copper electroplating solution is 30-60 ppm, for example, it can be 32 ppm, 35 ppm, 38 ppm, 40 ppm, 42 ppm, 45 ppm, 48 ppm, 50 ppm, 52 ppm, 55 ppm or 58 ppm, and specific point values between the above point values. Due to the limitation of length and for the sake of simplicity, the specific point values included in the range are not listed in this application.

[0046] In the present application, the chloride ions in the nanotwinned copper electroplating solution can be provided by hydrochloric acid and / or chloride salts, including sodium chloride (NaCl) and / or potassium chloride (KCl).

[0047] Exemplarily, the mass concentration of the hydrochloric acid is 36-38% (e.g., 36.5%, 37%, 37.5%, etc.), and the chloride ions are introduced into the nanotwinned copper electroplating solution by diluting the 36-38% hydrochloric acid.

[0048] In one embodiment, the solvent in the nanotwinned copper electroplating solution is water.

[0049] In one embodiment, the mass concentration of the plating solution additive in the nanotwinned copper electroplating solution is 5-500 ppm, for example, it can be 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, 120 ppm, 150 ppm, 180 ppm, 200 ppm, 220 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, or 450 ppm, and specific point values between the above point values, for the sake of brevity and simplicity, the specific point values included in the range are not listed in the present application, and further optionally 10-200 ppm.

[0050] In one embodiment, the nanotwinned copper electroplating solution further comprises any one or a combination of at least two of an accelerator, a leveler, and an inhibitor.

[0051] As an optional technical solution of the present application, in order to further improve the filling capacity of the nanotwinned copper electroplating solution, an accelerator, a leveler, an inhibitor, etc. are added as patterning additives to ensure good pattern filling capacity. Specifically, the accelerator can reduce the overpotential and accelerate the copper deposition speed during the copper electroplating process; the leveler is easily adsorbed on the cathode surface where the current density is high, and forms a competitive adsorption relationship with copper ions, thereby playing a leveling role.

[0052] In one embodiment, the accelerator comprises a sulfhydryl sulfonic acid compound, and further optionally 3-(benzothiazole-2-mercapto)-propane sulfonic acid sodium (ZPS) and / or 3-mercapto-1-propane sulfonic acid sodium (MPS).

[0053] In one embodiment, the mass concentration of the accelerator in the nanotwinned copper electroplating solution is 1-100 ppm, for example, it can be 5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm or 90 ppm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0054] In one embodiment, the leveling agent comprises a nitrogen-containing heterocyclic compound, and may be further selected from any one or a combination of at least two of sodium thiazolinyl dithiopropane sulfonate (SH110), 2-mercaptothiazoline, tetrahydrothiazothione (thiazothione H1), and pyridine salts.

[0055] In one embodiment, the mass concentration of the leveling agent in the nanotwinned copper electroplating solution is 1-100 ppm, for example, it can be 5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm or 90 ppm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0056] In one embodiment, the inhibitor comprises a polyether, and may further be any one or a combination of at least two of polyethylene glycol (PEG), polypropylene glycol (PPG), and polyoxyethylene-polyoxypropylene copolymer (EOPO copolyether).

[0057] In one embodiment, the mass concentration of the inhibitor in the nanotwinned copper electroplating solution is 1-100 ppm, for example, it can be 5 ppm, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm or 90 ppm, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0058] In this application, the preparation method of the nanotwinned copper electroplating solution is a method known in the art, and includes, by way of example, mixing copper salt, sulfuric acid, chloride ion source, plating solution additive, water and optionally accelerator, optionally leveling agent and optionally inhibitor evenly to obtain the nanotwinned copper electroplating solution.

[0059] In one embodiment, the chloride ion source includes hydrochloric acid and / or chloride salts.

[0060] Fourthly, this application provides a method for preparing nanotwinned copper by electroplating, the method comprising: electroplating on a substrate using the nanotwinned copper electroplating solution as described in the third aspect to obtain the nanotwinned copper.

[0061] In one embodiment, in the electroplating method, the substrate is used as a cathode, and a thin film of nanotwinned copper is formed on the surface of the substrate; the anode of the electroplating includes a soluble copper-phosphorus anode or an insoluble anode (e.g., a platinum electrode).

[0062] In one embodiment, the conductive material on the substrate includes a metal, such as copper, titanium, gold, nickel, and alloys thereof; and the substrate is a material including a thin film of conductive material, a printed circuit board, a flexible circuit board, a Si wafer, etc.

[0063] By way of example, the conductive material on the substrate can be prepared by electroplating, electroless plating, sputtering, casting, etc.

[0064] In one embodiment, the substrate is a pretreated substrate, and the pretreatment includes at least one of plasma cleaning, acid pickling, and water washing, to remove surface dust and oxides, and expose a fresh and clean substrate surface.

[0065] In one embodiment, the substrate (the pretreated substrate) is immersed in the nanotwinned copper electroplating solution for 5-120 seconds before electroplating; the immersion time can be 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, or 110 seconds, and specific point values between the above point values; for the sake of brevity, the specific point values included in the range are not listed herein, and further, 5-60 seconds can be optionally selected.

[0066] In one embodiment, the electroplating temperature is 10-60°C, such as 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or 55°C, and specific point values between the above point values; for the sake of brevity, the specific point values included in the range are not listed herein.

[0067] In one embodiment, the electroplating is performed under stirring.

[0068] In one embodiment, the stirring method includes at least one of magnetic stirring, central jet, and air blowing.

[0069] In one embodiment, the rate of stirring is 100-1000 rpm, for example, it can be 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm, 800 rpm or 900 rpm, and specific point values between the aforementioned point values, for the sake of brevity and conciseness, the specific point values included in the range are not exhaustively listed in this application.

[0070] In one embodiment, the electroplating method comprises direct current electroplating, further optionally direct current electroplating with constant current density.

[0071] In one embodiment, the current density of electroplating is 1-9 A / dm 2 , for example, it can be 1.5 A / dm 2 , 2 A / dm 2 , 2.5 A / dm 2 , 3 A / dm 2 , 3.5 A / dm 2 , 4 A / dm 2 , 4.5 A / dm 2 , 5 A / dm 2 , 5.5 A / dm 2 , 6 A / dm 2 , 6.5 A / dm 2 , 7 A / dm 2 , 7.5 A / dm 2 , 8 A / dm 2 or 8.5 A / dm 2 , and specific point values between the aforementioned point values, for the sake of brevity and conciseness, the specific point values included in the range are not exhaustively listed in this application, further optionally 3-9 A / dm 2 .

[0072] In one embodiment, the electroplating time is 0.1-300 min, for example, it can be 1 min, 5 min, 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 80 min, 90 min, 100 min, 120 min, 140 min, 150 min, 160 min, 180 min, 200 min, 220 min, 240 min, 250 min, 260 min or 280 min, and specific point values between the aforementioned point values, for the sake of brevity and conciseness, the specific point values included in the range are not exhaustively listed in this application.

[0073] In one embodiment, after the electroplating is completed, it further comprises the steps of cleaning and drying.

[0074] As an optional technical solution of the present application, the present application provides a nano-twin copper prepared by the aforementioned electroplating preparation method, wherein the preferred orientation of the nano-twin copper is (111) direction.

[0075] In one embodiment, the nano-twin copper comprises columnar crystals grown perpendicularly to the substrate.

[0076] In one embodiment, the diameter of the columnar crystals is 1-5 μm, for example, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm or 4.5 μm, and specific point values between the aforementioned point values. Due to the limited space and for the sake of simplicity, the present application does not list all the specific point values included in the range.

[0077] In one embodiment, the nano-twin copper contains a high density of horizontal twins in the interior, and the twin lamella spacing of the horizontal twins is 1-50 nm, for example, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm or 45 nm, and specific point values between the aforementioned point values. Due to the limited space and for the sake of simplicity, the present application does not list all the specific point values included in the range.

[0078] In one embodiment, the hardness of the nano-twin copper is 1.7-2.0 GPa, for example, 1.75 GPa, 1.8 GPa, 1.85 GPa, 1.9 GPa or 1.95 GPa, and specific point values between the aforementioned point values. Due to the limited space and for the sake of simplicity, the present application does not list all the specific point values included in the range.

[0079] In a fifth aspect, the present application provides applications of the nano-twin copper electroplating solution according to the third aspect and the electroplating preparation method according to the fourth aspect in integrated circuit manufacturing, circuit packaging, printed circuit board manufacturing or optoelectronic manufacturing.

[0080] Compared with the prior art, the present application has the following beneficial effects:

[0081] (1) The plating solution additive provided by the present application is reacted with an aldehyde compound using a protein additive, so that it has excellent stability and twin promoting effect, and does not affect the filling effect of the pattern additive. The nano-twin copper electroplating solution containing the plating solution additive has excellent stability, and does not appear turbidity, precipitation and discoloration and other phenomena after long-term storage, the pH value and appearance are stable, the shelf life and service life are significantly prolonged, the operation process window of electroplating is widened, and a nano-twin copper plating layer with excellent performance can be obtained.

[0082] (2) The nano-twin copper plating layer prepared by the nano-twin copper plating solution containing the plating solution additive has good consistency in the organizational morphology, has high (111) preferred orientation, contains columnar crystals growing perpendicularly to the substrate, and has high density of horizontal twins in the interior. The nano-twin copper plating layer has the characteristics of high hardness, high strength, high electrical conductivity, high electromigration resistance, oxidation resistance and thermal stability, and can be applied to various packaging, printed circuit boards, integrated circuits and other technical fields, including wafer substrates, carrier boards, PCBs and other application scenarios requiring plating.

[0083] Other aspects can become apparent from a review of the drawings and detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0084] The accompanying drawings are included to provide a further understanding of the technical solutions of the present application, and constitute a part of the specification, and are used together with the embodiments of the present application to explain the technical solutions of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0085] FIG. 1 is an organizational morphology diagram of the nano-twin copper plating layer prepared in Example 1;

[0086] FIG. 2 is an organizational morphology diagram of the nano-twin copper plating layer prepared in Example 2;

[0087] FIG. 3 is an organizational morphology diagram of the nano-twin copper plating layer prepared in Example 3;

[0088] FIG. 4 is an organizational morphology diagram of the nano-twin copper plating layer prepared in Comparative Example 1;

[0089] FIG. 5 is a hardness comparison diagram of the nano-twin copper plating layers prepared in Example 1 and Comparative Example 1;

[0090] FIG. 6 is a stability comparison diagram of the plating solution additives provided in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0091] The technical solutions of the present application will be further described by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0092] The terms "comprising", "including", "having", "containing", or any other similar term as used herein are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a listed element does not necessarily include only that element, but can include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0093] "Optionally" or "any of" means that the matter or event described thereafter can occur or not occur, and the description includes the case where the event occurs and the case where the event does not occur.

[0094] The indefinite articles "a" and "an," as used herein in the specification, unless clearly indicated to the contrary, should be understood to mean "at least one." The indefinite articles "a" and "an" thus "or" the plural is intended to mean "one or more" unless clearly indicated to the contrary by the context of use.

[0095] The materials, reagents and the like used in the following detailed description of the application are all conventional commercially available chemicals, wherein the gelatin is purchased from Aldrich (CAS No. 9000-70-8, Item No. G108394).

[0096] Example 1

[0097] A plating solution additive, the preparation method comprising: weighing 10 g of gelatin and dissolving it in 1000 mL of water, heating to 60°C and stirring to completely dissolve and mix uniformly, to obtain a 10 g / L gelatin solution; taking 4 g of acetaldehyde (CH3CHO) and adding it to 1000 mL of water, heating to 40°C and stirring for 10 min, completely dissolving and then preparing a 4 g / L acetaldehyde aqueous solution; mixing the acetaldehyde aqueous solution and the gelatin aqueous solution uniformly at a volume ratio of 4:1, monitoring the pH value with a pH meter while stirring, adjusting the pH to 11 with NaOH after the pH is stable, heating to 50°C and stirring for 2 h after the pH is stable, to obtain the plating solution additive.

[0098] A nano-twin copper electroplating solution, comprising the following components: copper ions 35 g / L, sulfuric acid 50 g / L, chloride ions 50 ppm, the plating solution additive provided in the present embodiment 65 ppm, accelerator (sodium 3-(benzothiazole-2-mercapto)-propane sulfonate, ZPS) 100 ppm, leveler (sodium thiazolinyl dithiopropyl sulfonate, SH110) 10 ppm; the solvent is pure water; wherein the copper ions are provided by CuSO4·5H2O, and the chloride ions are provided by hydrochloric acid. The preparation method of the nano-twin copper electroplating solution comprises: mixing CuSO4·5H2O, sulfuric acid, hydrochloric acid, the plating solution additive provided in the present embodiment, accelerator ZPS, leveler SH110 and pure water according to the aforementioned proportions, stirring uniformly, to obtain the nano-twin copper electroplating solution 1 L.

[0099] A method for electroplating nano-twin copper, using the nano-twin copper electroplating solution provided in the present embodiment, comprising the following steps: using a Si wafer material sputtered with copper and titanium as a substrate, plasma cleaning to remove dust and oxides on the surface of the substrate, to expose a fresh and clean substrate surface; using the substrate as a cathode and a soluble phosphor copper anode, immersing both in the nano-twin copper electroplating solution provided in the present embodiment, starting electroplating after soaking for 60 s, the parameters for electroplating being: constant temperature 30°C, current density 5 A / dm 2The nano-twin copper plating layer is obtained by electroplating for 80 min in a central jet stirring mode.

[0100] The microstructure of the nano-twin copper plating layer prepared in the embodiment is tested by a focused ion beam microscope (FIB, model Helios 5UX), and a microstructure pattern obtained is shown in FIG. 1. The plating layer contains columnar crystals growing perpendicularly to the substrate, the columnar crystals have a diameter of about 1-2 μm, and contain a high density of twins in the interior, and the twin lamella spacing is 5-20 nm.

[0101] The hardness of the nano-twin copper plating layer prepared in the embodiment is tested by a HXD-2000TMC / LCD digital microhardness tester. The copper plating layer has a thickness of about 40 μm, the hardness tester load is set to 50 g, and the pressure maintaining time is 10 s. The test is repeated 10 times to ensure the accuracy of the experimental results of the surface Vickers hardness value, and the average hardness value is 1.87 GPa.

[0102] Example 2

[0103] A plating solution additive is prepared by the following method: 5 g of gelatin is weighed and dissolved in 1000 mL of water, heated to 60℃ and stirred until completely dissolved and uniformly mixed to obtain a 5 g / L gelatin solution; 2 g of propyl aldehyde (CH3CH2CHO) is added to 1000 mL of water, heated to 40℃ and stirred for 10 min, and then completely dissolved to prepare a 2 g / L propyl aldehyde aqueous solution; the propyl aldehyde aqueous solution and the gelatin aqueous solution are uniformly mixed at a volume ratio of 4:1, and the pH value is monitored by a pH meter during stirring. After the pH value is stable, NaOH is added to adjust the pH value to 11. After the pH value is stable, the mixture is heated to 50℃ and stirred for 2 h to obtain the plating solution additive.

[0104] A nano-twin copper electroplating solution comprises the following components: 35 g / L of copper ions, 50 g / L of sulfuric acid, 50 ppm of chloride ions, 65 ppm of the plating solution additive provided in the embodiment, 100 ppm of an accelerator (sodium 3-(benzothiazole-2-mercapto)-propane sulfonate, ZPS), and 10 ppm of a leveling agent (sodium thiazolinyl dithiopropane sulfonate, SH110). Pure water is used as the solvent. The copper ions are provided by CuSO4·5H2O, and the chloride ions are provided by hydrochloric acid. A preparation method of the nano-twin copper electroplating solution comprises the following steps: the CuSO4·5H2O, sulfuric acid, hydrochloric acid, the plating solution additive provided in the embodiment, the accelerator ZPS, the leveling agent SH110, and pure water are mixed according to the aforementioned proportions, and stirred uniformly to obtain the nano-twin copper electroplating solution 1 L.

[0105] A method for electroplating nanotwinned copper, the method comprising the following steps: using a Si wafer material sputtered with copper and titanium as a substrate, plasma cleaning to remove dust and oxides on the surface of the substrate to expose a fresh and clean substrate surface; using the substrate as a cathode and a soluble phosphor copper anode, immersing the two in the nanotwinned copper electroplating solution provided in the embodiment, starting electroplating after 60 s of immersion, the electroplating parameters being: constant temperature 30℃, current density 5A / dm 2 , stirring mode being central jet, electroplating time 80 min, to obtain a nanotwinned copper coating.

[0106] The microstructure and hardness of the nanotwinned copper coating prepared in the embodiment are tested by the same method as in Embodiment 1, the obtained microstructure pattern is shown in FIG. 2, the coating contains columnar crystals growing perpendicularly to the substrate, the columnar crystal diameter is about 1-2μm, and the columnar crystals contain high-density horizontal twins, the twin lamella spacing is 10-25nm; the average value of the hardness test is 1.79GPa.

[0107] Embodiment 3

[0108] A plating solution additive, the preparation method comprising: weighing 10g gelatin, dissolving in 1000mL water, heating to 60℃ and stirring to completely dissolve and mix uniformly to obtain a 10g / L gelatin solution; taking 4g propylene aldehyde (CH2=CHCHO) and adding to 1000mL water, heating to 40℃ and stirring for 10min, completely dissolving to prepare a 4g / L propylene aldehyde aqueous solution; mixing the propylene aldehyde aqueous solution and the gelatin aqueous solution uniformly at a volume ratio of 4:1, monitoring the pH value with a pH meter during stirring, adding NaOH to adjust the pH to 11 after the pH is stable, heating to 50℃ and stirring to react for 2h to obtain the plating solution additive.

[0109] A nanotwinned copper electroplating solution, comprising the following components: copper ions 35g / L, sulfuric acid 50g / L, chloride ions 50ppm, and the plating solution additive provided in the embodiment 65ppm; the solvent being pure water; wherein the copper ions are provided by CuSO4·5H2O, and the chloride ions are provided by hydrochloric acid. The preparation method of the nanotwinned copper electroplating solution comprises: mixing CuSO4·5H2O, sulfuric acid, hydrochloric acid, the plating solution additive provided in the embodiment and pure water according to the aforementioned proportions, stirring uniformly to obtain the nanotwinned copper electroplating solution 1L.

[0110] A method for electroplating nanotwinned copper, which adopts a nanotwinned copper electroplating solution provided by the embodiment and comprises the following steps: taking a Si wafer material sputtered with copper and titanium as a substrate, performing plasma cleaning to remove dust and oxides on the surface of the substrate, and exposing a fresh and clean substrate surface; using the substrate as a cathode and a soluble phosphor copper anode as an anode, immersing the two in the nanotwinned copper electroplating solution provided by the embodiment, starting electroplating after 60 s of immersion, and setting the electroplating parameters as follows: constant temperature of 30℃, current density of 5A / dm 2 , stirring mode of central jet, and electroplating time of 80 min, to obtain a nanotwinned copper coating.

[0111] The microstructure and hardness of the nanotwinned copper coating prepared in the embodiment are tested by using the same method as in Embodiment 1, the obtained microstructure pattern is shown in FIG. 3, the coating contains columnar crystals growing perpendicularly to the substrate, the diameter of the columnar crystals is about 1-3μm, and the columnar crystals contain high-density twinning, the spacing between twinning lamellas is 10-50nm; the average value of the hardness test is 1.85GPa.

[0112] Embodiment 4

[0113] A plating solution additive, a preparation method thereof comprises the following steps: weighing 5g of gelatin, dissolving it in 1000mL of water, heating to 80℃, stirring to completely dissolve and uniformly mix, to obtain a gelatin solution; taking 5g of glutaraldehyde, adding it into 1000mL of water, heating to 30℃, stirring for 10min, completely dissolving to prepare an aldehyde aqueous solution; mixing the aldehyde aqueous solution and the gelatin aqueous solution uniformly at a volume ratio of 10:1, monitoring the pH value with a pH meter during stirring, adding NaOH to adjust the pH to 9 after the pH is stable, heating to 50℃ and stirring for 6h after the pH is stable, to obtain a reaction solution; performing dialysis on the reaction solution with a dialysis bag with a molecular weight cut-off of 50000, changing the water every 12h for a total of 3 times, evaporating and concentrating the dialyzed water solution to obtain the plating solution additive.

[0114] A nanotwinned copper electroplating solution, comprising the following components: copper ions 25g / L, sulfuric acid 50g / L, chloride ions 75ppm, the plating solution additive provided by the embodiment 275ppm, accelerator (3-mercapto-1-propane sulfonic acid sodium, MPS) 20ppm, and leveling agent (tetrahydrothiazole sulfone, H1) 2ppm; the solvent is pure water; wherein the copper ions are provided by CuSO4·5H2O, and the chloride ions are provided by hydrochloric acid. A preparation method of the nanotwinned copper electroplating solution comprises the following steps: mixing CuSO4·5H2O, sulfuric acid, hydrochloric acid, the plating solution additive provided by the embodiment, accelerator MPS, leveling agent H1, and pure water according to the aforementioned proportions, stirring uniformly, and obtaining the nanotwinned copper electroplating solution.

[0115] A method for electroplating nanotwinned copper, the method comprising the following steps: using a printed circuit board comprising a nickel conductive layer as a substrate, acid cleaning and pure water cleaning to remove surface dust and oxides and expose a fresh and clean substrate surface; using the substrate as a cathode and an insoluble platinum electrode as an anode, immersing the two in a nanotwinned copper electroplating solution provided by the present embodiment, starting electroplating after 60 seconds of immersion, the electroplating parameters being: constant temperature 40℃, current density 3A / dm 2 , stirring mode being magnetic stirring, electroplating time 80min, to obtain a nanotwinned copper plating layer.

[0116] The microstructure and hardness of the nanotwinned copper plating layer prepared in the present embodiment were tested using the same method as in Example 1, the plating layer comprising columnar crystals growing perpendicular to the substrate, the columnar crystals having a diameter of about 3-5μm and containing a high density of horizontal twins, the twin lamella spacing being 20-50nm; the average hardness value being 1.7GPa.

[0117] Example 5

[0118] A plating solution additive, the preparation method comprising: weighing 1g gelatin and dissolving it in 1000mL water, heating to 80℃ and stirring to completely dissolve and mix uniformly to obtain a gelatin solution; taking 1g benzaldehyde and adding it to 1000mL water, heating to 30℃ and stirring for 10min, completely dissolving to prepare an aldehyde aqueous solution; mixing the aldehyde aqueous solution and the gelatin aqueous solution uniformly at a volume ratio of 2:1, stirring to mix uniformly, then adding NaOH to adjust the pH value to 7, heating to 40℃ and stirring for 30min after the pH is stable. After the reaction, the reaction liquid is dialyzed using a dialysis bag with a molecular weight cut-off of 50000, changing the water every 12h for a total of 3 times, evaporating and concentrating the dialyzed aqueous solution to obtain the plating solution additive.

[0119] A nanotwinned copper electroplating solution, comprising the following components: copper ions 25g / L, sulfuric acid 50g / L, chloride ions 75ppm, a plating solution additive provided by the present embodiment 150ppm, an accelerator (sodium 3-(benzothiazole-2-mercapto)-propane sulfonate, ZPS) 100ppm, a leveler (sodium thiazolinyl dithiopropyl sulfonate, SH110) 10ppm; the solvent being pure water; wherein the copper ions are provided by CuSO4·5H2O and the chloride ions are provided by hydrochloric acid. The preparation method of the nanotwinned copper electroplating solution comprises: mixing CuSO4·5H2O, sulfuric acid, hydrochloric acid, the plating solution additive provided by the present embodiment, the accelerator ZPS, the leveler SH110 and pure water according to the aforementioned proportions, stirring uniformly to obtain the nanotwinned copper electroplating solution.

[0120] A method for electroplating nanotwinned copper, the method comprising the following steps: using a printed circuit board comprising a nickel conductive layer as a substrate, acid cleaning and pure water cleaning to remove surface dust and oxides and expose a fresh and clean substrate surface; using the substrate as a cathode and an insoluble platinum electrode as an anode, immersing the two in a nanotwinned copper electroplating solution provided by the embodiment, starting electroplating after 60 s of immersion, the electroplating parameters being: constant temperature 40℃, current density 3A / dm 2 , magnetic stirring, electroplating time 60 min, to obtain a nanotwinned copper plating layer.

[0121] The microstructure and hardness of the nanotwinned copper plating layer prepared in the embodiment are tested by the same method as in Example 1, the plating layer comprising columnar crystals growing perpendicular to the substrate, the columnar crystals having a diameter of about 2-5μm and containing a high density of horizontal twins inside, the twin lamellar spacing being 30-50nm; the average value of the hardness test being 1.79GPa.

[0122] Comparative Example 1

[0123] A nanotwinned copper electroplating solution, the difference between the solution and that of Example 1 being that the plating solution additive is equal-mass gelatin, and the types and contents of the other components are the same as in Example 1.

[0124] A method for electroplating nanotwinned copper, the difference between the method and that of Example 1 being that a nanotwinned copper electroplating solution provided by the comparative example is used, and the remaining process steps and parameters are the same as in Example 1, to obtain a nanotwinned copper plating layer.

[0125] The microstructure of the nanotwinned copper plating layer prepared in the comparative example is tested by the same method as in Example 1, and the obtained microstructure diagram is shown in Figure 4, the copper plating layer containing part of columnar crystals, the long axis crystal boundary of the columnar crystals being inclined at a large angle to the substrate, the columnar crystals having a diameter of about 0.5-3μm, and part of equiaxed crystals being present in addition to the columnar crystals, the columnar crystals containing twin lamellar layers inside, the twin lamellar spacing being 50-500nm.

[0126] The hardness of the nanotwinned copper plating layer prepared in the comparative example is tested by the same method as in Example 1, and a hardness comparison diagram of the comparative example 1 and Example 1 is shown in Figure 5, the average value of the hardness test of the nanotwinned copper plating layer of the comparative example 1 being 1.83GPa, which is lower than the hardness of Example 1.

[0127] The storage stability of the plating solution additives was tested: the pH values of the plating solution additives of Example 1 and Comparative Example 1 were tested after being placed at 25±2℃ for a certain period of time, and the pH value changes were recorded to characterize the stability. The stability comparison chart obtained is shown in FIG. 6. The plating solution additive provided by Example 1 had no obvious change in appearance and pH after being stored for 15 days, and could be stably stored for more than 90 days with minimal pH change. The plating solution additive of Comparative Example 1 used gelatin as the plating solution additive, and after being stored for 15 days, flocculent precipitate appeared and the pH showed a clear upward trend.

[0128] The applicant declares that the plating solution additive, the preparation method thereof, the nano-twin copper plating solution and the application thereof of the present application are illustrated by the above examples, but the present application is not limited to the above process steps, i.e. it does not mean that the present application must rely on the above process steps to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the materials selected by the present application, addition of auxiliary ingredients, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a plating solution additive, comprising: Protein-based additives are reacted with aldehyde compounds to obtain the plating solution additive.

2. The preparation method according to claim 1, wherein, The protein additives include any one or a combination of at least two of gelatin, collagen, and polypeptides.

3. The preparation method according to claim 1 or 2, wherein, The aldehyde compounds include aliphatic aldehydes and / or aromatic aldehydes, and may further be selected from any one or a combination of at least two of formaldehyde, acetaldehyde, propionaldehyde, glutaraldehyde, acrolein, and benzaldehyde.

4. The preparation method according to any one of claims 1-3, wherein, The mass ratio of the aldehyde compound to the protein additive is (1-30):1, and may further be (1.2-20):

1.

5. The preparation method according to any one of claims 1-4, wherein, The reaction is carried out in the presence of water; Optionally, the preparation method includes: mixing a protein additive, an aldehyde compound, and water to obtain a mixture; reacting the mixture to obtain the plating solution additive; Optionally, the concentration of aldehyde compounds in the mixture is 0.1-15 g / L.

6. The preparation method according to any one of claims 1-5, wherein, The pH value of the reaction is 7-11; Optionally, the reaction temperature is 30-50°C; Optionally, the reaction time is 5 min to 12 h.

7. The preparation method according to any one of claims 1-6, wherein, The reaction process also includes a purification step. Optionally, the purification method includes filtration and / or dialysis; Optionally, the molecular weight cutoff of the dialysis bag used for dialysis is 1,000-60,000, and more preferably 2,000-50,000.

8. A plating solution additive, wherein, The plating solution additive is prepared by the preparation method according to any one of claims 1-7.

9. A nano-twinned copper electroplating solution, wherein, The nanotwinned copper electroplating solution includes copper ions, sulfuric acid, chloride ions, and the plating solution additive as described in claim 8.

10. The nanotwinned copper electroplating solution according to claim 9, wherein, The concentration of copper ions in the nanotwinned copper electroplating solution is 20-60 g / L; Optionally, the concentration of sulfuric acid in the nanotwinned copper electroplating solution is 20-120 g / L.

11. The nanotwinned copper electroplating solution according to claim 9 or 10, wherein, The mass concentration of chloride ions in the nano-twinned copper electroplating solution is 30-60 ppm. Optionally, the mass concentration of the plating solution additive in the nanotwinned copper electroplating solution is 5-500 ppm, and more preferably 10-100 ppm.

12. The nanotwinned copper electroplating solution according to claim 9, wherein, The nanotwinned copper electroplating solution also includes any one or a combination of at least two of the following: accelerator, leveling agent, and inhibitor. Optionally, the accelerator comprises a mercaptosulfonic acid compound, and more preferably sodium 3-(benzothiazol-2-mercapto)-propanesulfonate and / or sodium 3-mercapto-1-propanesulfonate; Optionally, the mass concentration of the accelerator in the nanotwinned copper electroplating solution is 1-100 ppm; Optionally, the leveling agent includes nitrogen-containing heterocyclic compounds, and may further include any one or a combination of at least two of sodium thiazolinyl dithiopropane sulfonate, 2-mercaptothiazoline, tetrahydrothiazothione, and pyridine salts. Optionally, the mass concentration of the leveling agent in the nano-twinned copper electroplating solution is 1-100 ppm; Optionally, the inhibitor comprises a polyether, and may further be any one or a combination of at least two of polyethylene glycol, polypropylene glycol, and polyoxyethylene-polyoxypropylene copolymer; Optionally, the mass concentration of the inhibitor in the nanotwinned copper electroplating solution is 1-100 ppm.

13. A method for electroplating nanotwinned copper, comprising: The nanotwinned copper is obtained by electroplating on a substrate using the nanotwinned copper electroplating solution as described in any one of claims 9-12.

14. The electroplating preparation method according to claim 13, wherein, The electroplating temperature is 10-60℃; Optionally, the current density of the electroplating is 1-9 A / dm³. 2 ; Optionally, the electroplating time is 0.1-300 min.

15. The application of the nanotwinned copper electroplating solution as described in any one of claims 9-12, and the electroplating preparation method as described in claim 13 or 14, in integrated circuit manufacturing, circuit packaging, printed circuit board manufacturing, or optoelectronic manufacturing.

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