Method for nano-etching the surface of copper or a copper alloy

Abstract

The following method steps: i) providing a substrate having a surface of at least one copper or copper alloy, ii) contacting at least a portion of the surface of the copper or copper alloy with a pre-dip composition, iii) contacting at least a portion of the surface of the copper or copper alloy with an etching solution. In a method for nano-etching the surface of a copper or copper alloy, - the steps are carried out sequentially; - step ii) is a non-etching step; - step iii) is an etching step; - the pre-dip composition contains at least one sulfur-containing compound selected from the enumeration defined in the claims. A method characterized by this.

Description

Technical Field

[0001] The present invention relates to a method for nano-etching the surface of copper or a copper alloy. In particular, the present invention relates to a method for nano-etching the surface of copper or a copper alloy, which is useful in the field of the electronics industry for manufacturing printed circuit boards, IC substrates, interposers, and the like.

Background Art

[0002] In the manufacture of printed circuit boards, the surface of copper is treated to promote adhesion between the copper surface and a resist before coating the copper surface with a photoresist, solder resist, resin for permanent adhesion, or the like. Chemical etching is commonly used in the treatment of substrates having fine wiring patterns. In the manufacture of multilayer printed circuit boards, for example, an oxide layer is formed on the copper surface, and while maintaining the geometric shape of the oxide layer, the oxide layer is reduced to metallic copper by a reducing agent, thereby attempting to promote adhesion between the copper conductive pattern layer and the resin layer.

[0003] The negative pattern of the circuit is formed by a) a step of applying an etching resist, such as a polymer dry film resist or a metal resist, to a layer of copper, b) a step of etching and removing the copper portions not covered by the etching resist, and c) a step of removing the etching resist from the remaining copper circuit.

[0004] The etching solution applied for this operation is selected from various types of compositions such as a mixture of an oxidizing agent and an acid. Two main types of etching solutions are based on acids such as sulfuric acid or hydrochloric acid and contain hydrogen peroxide, copper ions, or ferric ions as oxidizing agents. Such etching solutions are disclosed in C.F. Coombs, Jr., "Printed Circuits Handbook", 5th Edition, 2001, Chapter 33.4.3, pages 33.14 - 33.15 and Chapter 33.4.5, page 33.17.

[0005] Regarding the line width value / line interval value and the thickness of the copper layer to be etched, due to the progress of circuit miniaturization, it is impossible to use conventional etching solutions such as the above.

[0006] European Patent No. 2241653 discloses a composition for microetching copper or copper alloy during the production of printed circuit boards. The composition contains a copper salt, a source of halide ions, a buffer system, and a benzothiazole compound as an etch refiner.

[0007] European Patent No. 2754732 discloses an aqueous composition and a method for applying the above aqueous composition to etch copper and copper alloys. The aqueous composition contains an Fe 3+ ion source, an acid, a derivative of triazole or tetrazole, and an etching additive selected from N-alkylated iminodipropionic acid, its salt, a modified polyglycol ether, and a quaternary ureylene polymer.

[0008] International Publication No. 2017 / 108513 discloses an aqueous etching solution and a method for treating the surface of copper or copper alloy. The aqueous solution contains at least one acid, at least one oxidizing agent suitable for oxidizing copper, at least one source of halide ions, and contains at least one polyamide.

[0009] European Patent No. 3034654 is a composition for microetching the surface of copper or copper alloy, and the composition contains an Fe 3+ ion source, a Br - ion source, an inorganic acid, and a benzothiazole compound as an etch refiner.

[0010] International Publication No. 02 / 04706 discloses an etching solution that is acidic, contains hydrogen peroxide, at least one 5-membered nitrogen-containing heterocyclic compound, and additionally at least one microstructural modifier selected from the group consisting of organic thiols, organic sulfides, organic disulfides, and thioamides.

[0011] The drawbacks of known etching methods are even more pronounced when copper tracks are produced by the semi-additive process (SAP, Figure 1A). Here, the bare dielectric substrate is first coated with a seed layer that acts as a conductive layer. The seed layer contains, for example, copper deposited by electroless plating. Next, a patterned resist layer is formed on the seed layer, and a thicker second copper layer is deposited by electroplating into the openings of the patterned resist layer on the seed layer. The patterned resist layer is removed, and the seed layer between the copper tracks deposited by electroplating needs to be removed by various etching processes. The seed layer deposited by electroless plating has a finer granular structure than the second copper layer deposited by electroplating. The different granular structures can result in different etching behaviors of the individual copper layers.

[0012] A similar situation occurs when copper tracks are produced by the modified semi-additive process (m-SAP) or the highly modified SAP (am-SAP), and a thick second copper layer is deposited into the openings of the patterned resist layer on the first thin copper layer. The first copper layer is produced, for example, by thinning a copper clad attached to the dielectric substrate. Moreover, both the first copper layer and the second copper layer have different granular structures.

[0013] Etching solutions based on sulfuric acid and hydrogen peroxide result in an undesirable undercut of the first copper layer during etching (Figure 1B), thereby leading to insufficient adhesion of the copper layer on the dielectric substrate.

[0014] Etching solutions based on sulfuric acid and ferric ions typically exhibit an etching behavior as shown in Figure 1C. This trapezoidal line shape is undesirable because the wider bottom of the etched copper line can lead to unacceptable circuit short circuits. This phenomenon resulting in trapezoidal etching results is referred to herein as "line shape change".

[0015] An even more undesirable side effect of copper etching is the overall reduction in line width. This is typically caused by over - etching that dissolves copper ions from all surfaces of the processed copper lines (see Fig. 1D).

Prior Art Documents

Patent Documents

[0016]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Patent Document 8

Non - Patent Documents

[0017]

Non - Patent Document 1

Non - Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0018] Accordingly, an object of the present invention is to provide a method for nano-etching copper and copper alloys that overcomes the limitations and drawbacks of the prior art. Another object of the present invention is to provide a method for etching copper and copper alloys that results in improved retention of the geometric structure of the processed copper lines or copper alloy lines, such as a rectangular line shape (measurable by the difference between the upper side and the bottom side), less noticeable line width reduction, and avoidance of undercut.

[0019] One object of the present invention is to provide a method for enhancing the adhesion between copper and a dielectric material while continuously maintaining an ultra-low roughness of the copper surface.

[0020] As a specific object, an adhesion performance represented as a minimum reduction in peel strength will be achieved after a high-accelerated stress test (HAST).

[0021] One object of the present invention is to reduce signal loss in high-frequency product applications.

Means for Solving the Problems

[0022] The above object is solved by the method for etching the surface of copper or copper alloy according to claim 1. Preferred embodiments of the present invention can be found in the dependent claims.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0024] Throughout this specification, percentages are weight percentages (wt.%) unless otherwise indicated. One exception is the yield, which is given as a percentage of the theoretical yield. Concentrations given in this specification refer to the volume of the entire solution unless otherwise indicated.

[0025] A method for nano-etching the surface of copper or a copper alloy comprises the following method steps: i) preparing a substrate having at least one surface of copper or a copper alloy; ii) contacting at least a part of the surface of the copper or copper alloy with a pre-dip composition; iii) contacting at least a part of the surface of the copper or copper alloy with an etching solution, characterized in that - the steps are carried out sequentially; - step ii) is a non-etching step; - step iii) is an etching step; - the pre-dip composition comprises a) a compound of formula (I)

[0026]

Chemical formula

[0027] (wherein X = S or S(O); R 1 ,R 2 ,R3 , R 4 = H, C1 - C6 alkyl, OH, preferably thiourea [X = S; R 1 , R 2 , R 3 , R 4 = H]), its derivatives, salts, and mixtures; b) A compound of formula (II)

[0028]

Chemical formula

[0029] (wherein, X = S, S(O), S - S; R 1 , R 2 , R 3 = H, C1 - C6 alkyl, OH, or R 1 + R 3 = CH = CH, R 5 = H, C1 - C6 alkyl, OH,

[0030]

Chemical formula

[0031] or R 3 + R 5 = CH = CH), its derivatives, salts, and mixtures; c) A compound of structure Y - H or Y 2 (thiol or disulfide) [provided that Y - =

[0032]

Chemical formula

[0033] (wherein X = S, R 6 = COOH, C1 - C6 alkyl; R 7 = H, NH 2, C1-C6 alkyl; R 8 = COOH, SO 3 H, C1-C3 alkyl)]; and d) 3-nitrobenzenesulfonic acid characterized by comprising at least one sulfur-containing compound selected from the group consisting of

[0034] The steps are carried out in the order shown above.

[0035] Step i) - preparing a substrate having a surface of at least one copper or copper alloy In the context of the present invention, the substrate may be any substrate including the surfaces of copper and copper alloys. The substrate may be made entirely of copper or a copper alloy, or the substrate may include a surface made of copper or a copper alloy. Preferably, the substrate is selected from copper foil, copper alloy foil, printed circuit board, IC substrate, interposer, copperized semiconductor wafer, and copper-clad laminate (CCL). A copperized semiconductor wafer means a wafer substrate having a copper structure or copper alloy structure such as trenches, lines, dots, etc.

[0036] In the present specification, the copper surface is preferably defined as being made of copper having 99 wt.% or more of copper. According to the present invention, the term "copper alloy" preferably refers to an alloy composed of 90 wt.% to 99 wt.% of copper. Preferably, the further components of the alloy are selected from one or more of boron, silicon, phosphorus, or another metal such as nickel, iron, cadmium, zinc, tin, titanium, etc.

[0037] A surface of electrodeposited (ED) copper or copper alloy is particularly preferred, more preferably having an average particle size d of 1-5 μm determined by SEM (scanning electron microscope) 50 having.

[0038] Step ii) - contacting at least a part of the surface of the copper or copper alloy with a pre-dip composition The method for treating the surface of copper or a copper alloy according to the present invention includes step ii). This step ii) is carried out between step i) and step iii).

[0039] From the prior art, for example, International Publication No. 2017 / 108513, the etching method can optionally include a so-called pretreatment step of the surface of copper or a copper alloy: It is known that the pretreatment is carried out between step i) and step iii). The pretreatment method of the surface of copper or a copper alloy is known in the art. Such pretreatment includes, inter alia, a step of washing, a step of removing unwanted layers such as chromate layers and / or oxide layers, and a step of attaching an organic monolayer (for example, a monolayer of an azole corrosion inhibitor, a leveller, or a bleaching agent compound typically used in electrolytic copper plating).

[0040] The step of washing the surface of copper or a copper alloy can be realized by various means known in the art. Typically, such a washing step optionally uses an aqueous solution which can be acidic or alkaline and contains a co-solvent such as a surfactant and / or glycol. The chromate layer can be removed, for example, by an oxidation treatment using an aqueous solution containing sodium persulfate and / or other oxidizing agents. The oxide layer or other unwanted residues on the surface of copper or a copper alloy can be removed by an acidic aqueous treatment. The organic monolayer can be formed by treating the surface of copper or a copper alloy with an aqueous solution containing an azole corrosion inhibitor such as benzotriazole.

[0041] In contrast, in the method of step ii) of the present invention, the pre-dip composition contains at least one sulfur-containing compound selected from the group consisting of several subgroups a) to d).

[0042] These subgroups a) to d) are specified below.

[0043] As used herein, the term "alkyl group" of the present invention includes a branched or unbranched alkyl group containing cyclic and / or acyclic structural elements, and the cyclic structural element of the alkyl group necessarily requires at least 3 carbon atoms. The term "C1-CX alkyl group" according to the present invention refers to an alkyl group having 1 to X carbon atoms. C1-C6 alkyl includes, for example, among others, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, iso-pentyl, sec-pentyl, tert-pentyl, neo-pentyl, and hexyl. A substituted alkyl group can theoretically be obtained by replacing at least one kind of hydrogen with a functional group such as amino, hydroxyl, thiol, alkoxyl, and thioalkyl. Preferably, the alkyl group is unsubstituted or the alkyl group is substituted with a hydroxyl group and / or an amino group.

[0044] As used herein and as used in the claims, the term "aryl" refers to a cyclic aromatic hydrocarbon residue, such as phenyl or naphthyl, for example benzothiazolyl, in which individual ring carbon atoms can be replaced by N, O, and / or S. Further, the aryl residue can in each case be substituted by replacing hydrogen with a functional group such as amino, hydroxyl, thiol, alkoxyl, and thioalkyl. Preferably, the aryl group is unsubstituted or the alkyl group is substituted with a hydroxyl group and / or an amino group.

[0045] As used herein and as used in the claims, the term "aralkyl" refers to a hydrocarbon residue consisting of an alkyl group and an aryl group, such as benzyl and tolyl.

[0046] a) A compound of formula (I) A compound of formula (I)

[0047] [Chemical formula]

[0048] (wherein, X = S or S(O); R 1 , R 2 , R 3 , R 4 = H, C1-C6 alkyl, OH), its derivatives, salts, and mixtures;

[0049] b) A compound of formula (II) The compound of formula (II)

[0050]

Chemical formula

[0051] (wherein, X = S, S(O), S-S; R 1 , R 2 , R 3 = H, C1-C6 alkyl, OH, or R 1 + R 3 = CH=CH, R 5 = H, C1-C6 alkyl, OH, or R 3 + R 5 = CH=CH,

[0052]

Chemical formula

[0053] ) its derivatives, salts, and mixtures;

[0054] Formulas (I) and (II) contain the same structural elements of formula (III):

[0055]

Chemical formula

[0056] The dashed lines in formula (III) indicate that one of each bond is a double bond and the other is a single bond.

[0057] Additional substituents on the N atom and possibly on the X group are not shown.

[0058] This results in two possible structural elements. One is where the double bond is between the carbon atom of the X group and the S atom; simultaneously, the bond between the carbon atom and the second N atom is a single bond. This structural element is represented by formula (IV):

[0059]

Chemical formula

[0060] The other possible structural element is where the double bond is between the carbon atom and the second N atom; simultaneously, the bond between the carbon atom of the X group and the S atom is a single bond. This requires that X has at least one additional substituent, which is also not shown. This structural element is represented by formula (V):

[0061]

Chemical formula

[0062] c) Compounds of structure Y-H or Y 2 (thiols or disulfides) [provided that Y- =

[0063]

Chemical formula

[0064] (where X = S R 6 = COOH, C1-C6 alkyl; R 7 = H, NH 2 , C1-C6 alkyl; R 8 = COOH, SO 3 H, C1-C3 alkyl)] The derivatives, salts, and mixtures thereof;

[0065] d) 3-Nitrobenzenesulfonic acid 3-Nitrobenzenesulfonic acid.

[0066] Step ii) is a non-etching step.

[0067] This means that a significant mass loss of copper or a copper alloy cannot be detected during step ii).

[0068] The mass loss is determined as follows. The "dry" panel is the mass before and after treatment. For a standard 15 cm × 7.5 cm board, if both sides contain copper, a mass difference of 10 mg is related to an etch depth of 50 nm. "No significant mass loss" means that the mass loss of the panel is 2 mg or less per panel, preferably 1 mg or less per panel.

[0069] The pH value of the pre-dip composition according to the present invention is preferably -1 to 11.

[0070] For a pH below 7, the pH is adjusted with at least one acid selected from inorganic acids and / or organic acids. Preferred acids are gluconic acid, sulfuric acid, formic acid, propionic acid, and methanesulfonic acid (MSA).

[0071] For a pH above 7, the pH is adjusted with at least one base selected from alkalis. Inorganic alkalis (KOH, NaOH) are preferred. NaOH is most preferred.

[0072] In the method of step ii) of the present invention, the pre-dip composition contains at least one sulfur-containing compound selected from the group consisting of several subgroups a) to d). The total concentration of the sulfur-containing compound specified above, selected from the group consisting of several subgroups a) to d), is preferably in the range of 20 mg / l to 20 g / l, more preferably in the range of 50 mg / l to 10 g / l, and even more preferably in the range of 100 mg / l to 1 g / l.

[0073] The temperature of the pre-dip composition in step ii) is preferably in the range of 20 to 70 °C, more preferably in the range of 20 to 55 °C, and even more preferably in the range of 30 to 55 °C.

[0074] The contact time between the pre-dip composition and the surface of the copper or copper alloy must be adjusted with respect to the temperature of the pre-dip composition. The contact time between the pre-dip composition and the surface of the copper or copper alloy is typically in the range of 15 to 600 seconds, more preferably in the range of 15 to 300 seconds, and even more preferably in the range of 30 to 90 seconds.

[0075] Step iii) - a step of bringing at least a part of the surface of the above copper or copper alloy into contact with an etching solution Step iii) is an etching step.

[0076] This means that a significant difference in copper and copper alloys can be detected before / after step iii) by mass loss measurement. The mass loss is determined as described above. "Significant mass loss" means that the mass loss of the panel is 1 mg or more per panel, preferably 5 mg or more per panel.

[0077] Etching solution The etching solution contains at least one oxidizing agent suitable for oxidizing copper. An oxidizing agent suitable for oxidizing copper typically has a standard oxidation potential greater than that of copper for a given concentration and pH value. Typically, the concentration of at least one oxidizing agent suitable for oxidizing copper ranges from 0.05 to 20 wt.%, preferably from 1.0 to 10.0 wt.% or 15 wt.%.

[0078] Preferably, the at least one oxidizing agent is selected from the group consisting of peroxides such as metal peroxides like hydrogen peroxide, sodium peroxide, potassium peroxide; metal superoxides such as potassium superoxide; copper ions and ferric ions. To prevent the decomposition of peroxides, other additional compounds such as p-phenolsulfonic acid can be added. Peroxides and superoxides are preferably contained at a concentration in the range of 1 to 150 g / l.

[0079] Ferric ions can be provided by any water-soluble source of ferric ions, such as an iron(III) salt (i.e., a ferric salt) or an iron(III) complex. Preferably, the ferric ion source is selected from the group consisting of ferric sulfate (Fe 2 (SO 4 ) 3 )), ferric chloride (FeCl 3 ), ferric bromide (FeBr 3 ), ferric nitrate (Fe(NO 3 ) 3 ), ferric acetate (Fe(OC(O)CH 3 ) 3 ), ferric hydroxide (Fe(OH) 3 ), their respective hydrates, and mixtures of those described above. Ferric ions are preferably contained at a concentration in the range of 1 to 50 g / l.

[0080] Copper ions can be provided by any water-soluble source of copper ions, such as a copper salt or a copper complex. Any water-soluble copper salt is a possible source of copper ions, and preferred copper ion sources are copper(II) sulfate, copper(II) chloride, copper(II) bromide, copper(II) acetate, copper(II) formate, copper(II) oxide, copper(II) hydroxide, copper(II) alkyl sulfonate, copper(II) aryl sulfonate, their hydrates, and mixtures of those described above. The copper ions are preferably contained at a concentration in the range of 1 to 70 g / l.

[0081] At least one oxidizing agent can be selected from the group consisting of copper ions and ferric ions. The etching solution can include at least one ferric ion source and at least one copper ion source as the oxidizing agent.

[0082] The etching solution includes at least one acid. The at least one acid is preferably selected from the group consisting of sulfuric acid, alkyl sulfonic acids such as methanesulfonic acid, aryl sulfonic acids such as phenylsulfonic acid, toluenesulfonic acid, nitric acid, phosphoric acid, formic acid, acetic acid, propionic acid, and mixtures thereof. Sulfuric acid, alkyl sulfonic acids, and aryl sulfonic acids are more preferred because of their high conductivity, which makes them extremely useful when the etching solution is regenerated by electrolytic means. The total concentration of the acids specified above is preferably in the range of 10 to 250 g / L.

[0083] The etching solution optionally contains at least one halide ion source. Chloride ion sources and bromide ion sources are preferred. Fluoride ions are extremely toxic in an acidic medium and may form hydrofluoric acid, which is difficult to handle. On the other hand, iodine ions may be oxidized in the etching solution, rendering the iodine ions ineffective. Examples of suitable chloride ion sources are water-soluble chloride salts. Preferably, at least one chloride ion source is selected from the group consisting of hydrogen chloride, water-soluble metal chlorides such as alkali metal chlorides like lithium chloride, sodium chloride, potassium chloride, and cesium chloride, alkaline earth metal chlorides such as manganese chloride, calcium chloride, strontium chloride, and barium chloride, transition metal chlorides such as manganese chloride, iron chloride, cobalt chloride, nickel chloride, copper chloride, and zinc chloride, ammonium chloride, and mixtures thereof. More preferably, at least one chloride ion source is selected from the group consisting of hydrogen chloride, alkali metal chlorides, and ammonium chloride. Examples of suitable bromide ion sources are water-soluble bromide salts. Preferably, at least one bromide ion source is selected from the group consisting of hydrogen bromide, water-soluble metal bromides such as alkali metal bromides like lithium bromide, sodium bromide, potassium bromide, and cesium bromide, alkaline earth metal bromides such as manganese bromide, calcium bromide, strontium bromide, and barium bromide, transition metal bromides such as manganese bromide, iron bromide, cobalt bromide, nickel bromide, copper bromide, and zinc bromide, ammonium bromide, and mixtures thereof. More preferably, at least one bromide ion source is selected from the group consisting of hydrogen bromide, alkali metal bromides, ammonium bromide, and zinc bromide. In a preferred embodiment of the present invention, the concentration of halide ions is 1 mg / l or more. In a more preferred embodiment of the present invention, the concentration of halide ions is 5 mg / l or more. When ferrous ions are used as the sole oxidizing agent, the concentration of all halide ions is preferably in the range of 1 to 500 mg / l, more preferably 10 to 200 mg / l, and most preferably 20 to 100 mg / l.When a peroxide or a superoxide is used as the sole oxidizing agent, the concentration of all halide ions is preferably in the range of 1 to 50 mg / l, more preferably in the range of 5 to 30 mg / l. When copper ions are used as the sole oxidizing agent, the concentration of all halide ions is preferably in the range of 0.1 to 200 g / l, more preferably in the range of 1 to 100 g / l. Optionally, halide ions can also be provided by ferric halide or copper halide as the oxidizing agent. Halide ions can prevent the undesirable etching of extremely thin copper lines, for example, those with a width of less than 10 μm, and improve the etching results as long as the change in line shape is not very noticeable.

[0084] The etching solution optionally contains at least one azole corrosion inhibitor selected from the group consisting of benzotriazole, 5-methylbenzotriazole, 1H-1,2,3-methylbenzotriazole, imidazole, 1H-1,2,3-triazole, 4-methylthiazole, 3-amino-1H-1,2,4-triazole, 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, and 5-amino-1H-tetrazole. Preferably, the azole corrosion inhibitor is selected from 1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, and 5-amino-1H-tetrazole, and the tetrazole derivative itself provides improved stability of the etching solution. The addition of the azole corrosion inhibitor advantageously reduces the corrosion of the metal surface being treated due to the formation of a protective azole layer and, optionally, also reduces the formation of precipitates from the etching solution during use. Often, after the elution of some copper from the surface of copper or a copper alloy, precipitates are formed that limit the life of the etching solution. When the etching solution contains at least one azole corrosion inhibitor, the total concentration of the optional azole corrosion inhibitor is preferably in the range of 0.01 to 2.0 wt.%.

[0085] The etching solution optionally contains at least one polyalkylene glycol compound, such as polyethylene glycol, polypropylene glycol, a copolymer of polyethylene glycol and polypropylene glycol, and derivatives thereof, all of which can improve the wettability of the surface of the copper or copper alloy to be treated, and thus can improve the etching behavior of the etching solution according to the present invention. When the etching solution contains at least one polyalkylene compound, the total concentration of the optional polyalkylene compound in the etching solution ranges from 100 to 2000 mg / l.

[0086] When the etching solution contains iron(III) as an oxidizing agent, it optionally further contains at least one ferrous ion source. The ferrous ions can be provided by any water-soluble source of ferrous ions, such as a ferrous salt (i.e., a ferrous iron salt) or a ferrous complex. Preferably, the ferrous ion source is selected from the group consisting of ferrous sulfate (FeSO 4 ), ammonium ferrous sulfate ((NH 4 ) 2 Fe(SO 4 ) 2 ), ferrous chloride (FeCl 2 ), ferrous bromide (FeBr 2 ), ferrous nitrate (Fe(NO 3 ) 2 ), ferrous acetate (Fe(OC(O)CH 3 ) 2 ), and ferrous hydroxide (Fe(OH) 2 ), and their respective hydrates. The optional ferrous ions are preferably used at a concentration in the range of 1 to 50 g / l. The use of the optional ferrous ions is particularly useful when ferric ions are used as the oxidizing agent and the regeneration of the etching solution is desired.

[0087] The etching solution according to the present invention is an aqueous solution. This means that the dominant solvent is water. Other solvents compatible with water, such as polar solvents like alcohols, glycols, and glycol ethers, may be added. From an environmental perspective, it is preferable to use only water (i.e., more than 99 wt.% based on all solvents).

[0088] The pH value of the etching solution according to the present invention is preferably ≦ 11, more preferably ≦ 7, even more preferably ≦ 4, and most preferably ≦ 1.5. Particularly preferably, the pH value of the etching solution according to the present invention is ≦ 1.0.

[0089] The etching solution according to the present invention may be prepared by dissolving all components in water. If solubility problems occur, pH regulators such as acids and bases may be used to increase the solubility of the components to be dissolved. The etching solution may also be prepared by preparing a concentrated solution that is diluted and / or mixed before use of the etching solution according to the present invention.

[0090] In one embodiment of the present invention, the etching solution has, for each individual component, the concentrations defined above, a) at least one acid; b) at least one oxidizing agent suitable for oxidizing copper; c) optionally, at least one halide ion source; d) at least one solvent, preferably water; e) optionally, at least one azole corrosion inhibitor; f) optionally, at least one polyalkylene compound; and g) optionally, at least one ferrous ion source is an aqueous solution containing or consisting of them.

[0091] In a preferred embodiment of the present invention (referred to herein as the "ferric ion etching solution"), the etching solution is a) at least one acid; b) Preferably, at least one second iron ion source at a concentration in the range of 1 to 50 g / l; c) At least one halide ion source; d) At least one solvent, preferably water; e) Optionally, at least one azole corrosion inhibitor; and f) Optionally, at least one polyalkylene compound which is an aqueous solution containing or consisting of these.

[0092] In another preferred embodiment of the present invention (referred to herein as "copper ion etching solution"), the etching solution is a) At least one acid; b) Preferably, at least one copper ion source at a concentration in the range of 1 to 70 g / l; c) At least one halide ion source; d) At least one solvent, preferably water; e) Optionally, at least one azole corrosion inhibitor; and f) Optionally, at least one polyalkylene compound which is an aqueous solution containing or consisting of these.

[0093] In another preferred embodiment of the present invention, the etching solution has, for each individual component, the concentrations defined above, a) At least one acid; b) At least one oxidizing agent selected from the group consisting of peroxides and superoxides; c) Optionally, at least one halide ion source; d) At least one solvent, preferably water; e) Optionally, at least one azole corrosion inhibitor; and f) Optionally, at least one polyalkylene compound which is an aqueous solution containing or consisting of these.

[0094] Etching solutions containing peroxides or superoxides as oxidizing agents are particularly useful for roughening the surface of copper or copper alloys. Using the etching solution according to the present invention, it is possible to completely remove the seed layer even in regions having a high conductor density.

[0095] According to the present invention, the etching solution can be used for etching the surface of copper or copper alloys, and thus, while avoiding substantial line shape changes, undercuts, and line width reduction, for the surface of copper or copper alloys or for the organic matrix bonded thereto, it enables a final finish such as an organic matrix or substituted tin that is sequentially and firmly bonded. Therefore, sufficient adhesion of the organic matrix and the final finish can be achieved.

[0096] In this specification, step iii) is also referred to as the "treatment step". The contact between at least a part of the surface of copper or copper alloy and the etching solution can be effected by any means known in the art. Typically, the etching solution is sprayed, applied, or placed on the surface of copper or copper alloy, or the surface of copper or copper alloy can be immersed or dipped in the etching solution. Preferably, the etching solution is sprayed onto the above surface. The transfer of the etching solution to the surface is also improved, and the diffusion process is also minimized.

[0097] The etching solution can also be used in horizontal devices, reel-to-reel devices, vertical devices, and vertical conveyor devices.

[0098] The temperature of the etching solution in step iii) is preferably in the range of 20 to 50°C. A higher temperature of the etching solution results in a faster etching process of the surface of copper or copper alloy. However, too high a temperature may have an adverse effect on the stability of the etching solution.

[0099] The contact time between the etching solution and the surface of copper or a copper alloy must be adjusted with respect to the temperature of the etching solution and the desired etching depth. The contact time between the etching solution and the surface of copper or a copper alloy is typically in the range of 5 to 300 seconds. In some cases, for example, when more copper is to be removed, it is necessary to adjust the contact time for the desired etching result. This adjustment can be carried out by means of a given experiment as required.

[0100] The method according to the invention can include a step of flushing with a solvent such as water during the individual method steps. In particular, after the contact between the surface of copper or a copper alloy and the etching solution, it is recommended to flush the surface of copper or a copper alloy with water in order to remove any unwanted residues of the solution. The method according to the invention can further include a drying step. For example, after the treatment step, it is possible to flush the surface of copper or a copper alloy with hot water and subsequently dry it using hot air or in an oven. The surface of copper or a copper alloy can then be immersed in or treated with a diluted acid solution (for example, 10 wt.% hydrochloric acid or 10 wt.% sulfuric acid) before any further processing.

[0101] Further steps (optional) The method for treating the surface of copper or a copper alloy according to the invention optionally comprises the following steps iv) contacting the surface of copper or a copper alloy with a post-dip solution and further comprises.

[0102] This step is referred to as the "post-dip step".

[0103] Optional step iv) (post-dip step) is included after step iii) (treatment step) in the method of treating the surface of copper or a copper alloy according to the present invention. The step of bringing the surface of the copper or copper alloy into contact with the post-dip is selected from the same possibilities given for the contact between the etching solution and the surface of the copper or copper alloy in step iii). The same contact possibilities or different contact possibilities can be selected. When the post-dip step is carried out, it is convenient to completely rinse the surface of the copper or copper alloy or to remove any residue from the surface of the copper or copper alloy before photo-resist application or solder mask application.

[0104] Various post-dip solutions can be used. A plurality of classifications are described below. Each name describes the main characteristics. However, combinations of these characteristics are also possible.

[0105] The acidic post-dip solution is an aqueous solution containing at least one acid, preferably hydrochloric acid. The pH value of the acidic post-dip is typically 1 or less. The acidic post-dip is typically used when copper chloride is used as an oxidant in the etching solution. Alternatively, when the photo-resist is applied sequentially or at a later stage in the method according to the present invention, an acidic post-dip can be used. The reason is that the photo-resist is liable to change with respect to alkaline treatment or such alkaline residues are present on the surface to which the photo-resist adheres.

[0106] The alkaline post-dip solution contains at least one hydroxide ion (OH -)It is an aqueous solution containing a source. Such a hydroxide ion source may be any water-soluble compound that releases or forms hydroxide ions such as a base upon contact with water. Preferably, the hydroxide ion source is selected from metal hydroxides such as alkali hydroxides and amines such as ammonia. The pH value of the alkaline post-dip solution is typically 10 or more. The alkaline post-dip solution is optionally used when the solder mask is unstable with respect to acidic treatment or acidic residues on the surface to which the solder mask is attached, when applied sequentially or at any subsequent stage, or when an oxidizing agent other than copper ions is present in the etching solution.

[0107] The organic post-dip solution contains at least one organic molecule such as those disclosed in European Patent No. 2020 / 055192 and / or European Patent No. 2019 / 061526, which are incorporated herein by reference. It has been found that the organic post-dip solution can have many advantages such as an anti-tarnish effect, enhancing adhesion to resin materials (e.g., for permanent adhesion or for solder resist), and / or increasing the darkening effect.

[0108] The method for treating the surface of copper or a copper alloy according to the present invention optionally includes the following steps v) laminating an organic matrix on the surface of the treated copper or copper alloy further includes.

[0109] The organic matrix includes, but is not limited to, prepreg, epoxy resin hardener, solder mask, photoresist, etc. The prepreg is a fiber-reinforced plastic, and typically, a glass-reinforced epoxy matrix such as FR-4, FR-5, and continuous build-up film (e.g., Ajinomoto GX92, Ajinomoto GXT31) is used.

[0110] Alternatively, or in addition to step v), the step vi) depositing a final finish on the surface of the treated copper or copper alloy or a part thereof can be included in the method according to the present invention.

[0111] The above final finish includes finishes such as replacement tin, electroless nickel immersion gold plating (ENIG), electroless nickel electroless palladium immersion gold plating (ENEPIG), electroless palladium immersion gold plating (EPIG), replacement silver, and organic solder preservatives (OSP). These finishes are well established in the art. Useful tin deposition methods include, for example, replacement tin plating described in European Patent No. 2476779.

[0112] Advantageously, the method according to the present invention hardly causes or does not cause deterioration of the line shape because there is almost no or no copper elution from the sides of the copper trenches and copper lines.

[0113] Various objects and their realizations by the method of the present invention are described below.

[0114] Surface morphology The method of the present invention creates cavities on the surface of copper or a copper alloy, and the plurality of cavities are obtuse angles with respect to the upper surface, and the plurality of cavities have a depth of at least 50 nm and less than 500 nm.

[0115] The morphologies of various copper surfaces were observed by FE-SEM after steps ii) and iii) of the method of the present invention. The results are shown in Figure 3.

[0116] After step ii), the DC copper surface shows a very smooth surface profile with visible polycrystalline copper grain sizes. Islands of various crystal grain sizes are uniformly distributed along the surface (Figure 3, upper left).

[0117] A similar surface profile is observed in the circuitized sample (Figure 3, lower left).

[0118] After step iii), the shallow cavities resulting from copper removal act by the etching chemistry. The copper removal in the z-direction (trench etching) followed the island boundaries of the copper grains pre-detected on the pre-dip treated surface. The grain boundaries of copper are the preferred side indicators for copper removal by etching. The grain boundaries of state-of-the-art copper act as sinks and transport paths for site defects by corrosion chemistry. This is also a demonstrated phenomenon that occurs on the copper surface in etching chemistry. Therefore, a morphology containing nano-sized cavities is obtained on the copper surface sequentially treated with the etching solution.

[0119] Ultra-low roughness The main objective of the method of the present invention was to enhance the adhesion between copper and dielectric materials while continuously maintaining the ultra-low roughness of the copper surface. Two roughness measurements were carried out to measure the surface roughness increase due to the treatment of the method of the present invention. Atomic force microscopy (AFM) was used as the selected method for measuring the surface roughness at the nanoscale due to its higher resolution. In Figure 4, it can be easily seen that Sa, Sq, and St measured by AFM of the copper surface showed only a slight increase due to the treatment of the method of the present invention compared to the untreated surface.

[0120] The respective measured values are as follows. Sa: Average surface roughness Sq: Root mean square roughness St: Peak-to-peak RSAI: Relative surface area increase

[0121] In contrast, the measured relative surface area increase (RSAI%) of the surface treated by the method of the present invention was shown to be up to 40% higher than that of the untreated surface, indicating a large increase.

[0122] The method of the present invention produces a surface that represents a nano-structure rather than a micro-structure. Therefore, the ultra-low roughness of the copper surface required is achieved by the method of the present invention.

[0123] In the method of the present invention, the substrate including the surface of copper or a copper alloy is preferably selected from a copper foil, a copper alloy foil, a printed circuit board, an IC substrate, an interposer, a copper-plated semiconductor wafer, and a copper-clad laminate.

[0124] In a preferred embodiment, a method of creating cavities on the surface of copper or a copper alloy is provided.

[0125] In a more preferred embodiment, the plurality of cavities are at an obtuse angle with respect to the upper surface.

[0126] In another more preferred embodiment, the plurality of cavities have a depth of at least 50 nm and less than 500 nm.

[0127] Preferably, the article having the surface of copper or a copper alloy is a patterned sample.

[0128] In the method of the present invention, the dimensional change of the pattern is less than 10% of the original value, preferably the dimensional change of the pattern is less than 7% of the original value, more preferably the dimensional change of the pattern is less than 5% of the original value, and most preferably the dimension of the pattern does not change.

[0129] In a specific embodiment, the dimensional change is a line width reduction.

[0130] Therefore, in the preferred method of the present invention, the line width reduction is less than 10% of the original value, preferably the line width reduction is less than 7% of the original value, more preferably the line width reduction is less than 5% of the original value, and most preferably the line width reduction is 0% of the original value.

[0131] As shown in FIG. 5, all the dimensions (L / S) of the circuitized copper remained substantially unchanged from the untreated stage. In comparison, in the left part of FIG. 5, when the conventional adhesion strengthening method is used, a substantial reduction in line width is clearly seen. In the present invention, when smaller dimensions are processed, the reduction is further worsened.

[0132] Without wishing to be bound by any particular theory or explanation, the following is assumed: To explain the aforementioned phenomenon, first, regarding the mechanism of how copper is removed from the surface, the differences between the methods must be understood (FIG. 6). The essence of the copper etching technology was the use of an oxidizing agent (strong oxidizing agent), a solvent (acid and / or solvent), and an etching additive. The optimal combination of these components would simultaneously determine the rate of copper removal and the preferred reaction sites on the surface. The elemental chemical composition of the conventional etching method was usually designed to react with the copper surface at all sites, and the removal was not selective (FIG. 6b). In addition to striking the vulnerable copper grain boundaries, this chemical action also extends to the copper grains. The etching down-recession of the underlying copper layer was enhanced. Therefore, excessive line width reduction is inevitable. In contrast to the conventional etching method, step (iii) of the method of the present invention prevents the striking of copper grains. It preferentially dissolves the dislocation sites at the grain boundaries. Therefore, the formation of surface roughness without line width reduction is achievable.

[0133] Adhesion performance The adhesion performance between copper and the dielectric material was evaluated by a peel strength test. The measurement unit is N / cm. Despite its ultra-low roughness characteristics, the copper foil treated by the method of the present invention shows outstanding good adhesion performance with various dielectric materials (FIG. 7).

[0134] Immediately after lamination (initial), the peel strength of the samples treated by the method of the present invention is the same as that of the untreated ones. This is demonstrated for both dielectric materials. The peel strength is about 8 N / cm and about 6 N / cm for Material 1 (Ajinomoto GXT31) and the new Material 2 (Ajinomoto GYXX), respectively. The specific differences in the peel strength forces suggest variations in material properties. In the highly accelerated stress test (HAST) test, the test pieces are subjected to water moisture penetration at the copper / dielectric material interface. The subsequent decrease in peel strength is mainly caused by water molecules in the humidity oven chamber. Due to the weak interfacial bond of the copper / dielectric material and the higher interaction energy between water and the copper surface, the penetrated water molecules displace the bond. This can be seen for the untreated surface in Figure 7, where the peel strength after HAST significantly deteriorated from 7.8 N / cm (initial) to 3.1 N / cm (after HAST) and from 6 N / cm (initial) to 2.9 N / cm (after HAST) for Material 1 and the new Material 2, respectively.

[0135] The sample pieces of the method of the present invention incorporated were able to withstand the HAST test with only a minimal decrease in peel strength after the test due to the mechanical fixation from the nanostructures generated in step iii) of the method of the present invention, as well as the chemical bonds from the pre-coating and the coating. The strong interfacial bond of the copper / dielectric material prevents the adverse effect of water molecule penetration at the interface.

[0136] To distinguish the different contributions of the strengthening mechanisms, a set of sample pieces was prepared for the peel strength test. To minimize problems in data interpretation, only Material 1 was used for the evaluation. Copper foils were laminated with the dielectric material in each successive step of the method of the present invention, and the initial peel strength data and the peel strength data after HAST are shown in FIG. 8. Similar to the previously observed peel strength data, there is no clear difference among the tested sample pieces immediately after lamination (initial). The peel strength after HAST of the sample pieces that were only pre-dip treated has the most pronounced decrease. This means that the decrease is most significant when the method is carried out including Steps i) and ii) without including Step iii). In contrast, when the method is carried out according to the present invention, i.e., including all of Steps i) to iii), the peel strength after HAST is improved by 40%. This suggests that the formation of nanostructures on the surface in Step iii) has an essential contribution to the adhesion strengthening. Nevertheless, when the test pieces are treated sequentially with pre-coating and coating, i.e., additionally including Step iv) where the post-dip solution is an organic post-dip solution, the peel strength further increases by 67%.

[0137] Low signal loss of the method of the present invention One of the main purposes of the ultra-low roughness adhesion strengthening system is to reduce signal loss in high-frequency product applications. Therefore, further tests were carried out to measure the signal insertion loss in the high-frequency bandwidth. In this case, the frequency applied to the test was 28 GHz. Using a low Df dielectric material and copper treated with the method of the present invention, test pieces of the build-up assembly were produced. At the same time, additional test pieces of untreated copper and low roughness oxide replacement (OR) were also included to benchmark the performance (FIG. 9).

[0138] The ultra-low roughness characteristics of the method of the present invention are clearly advantageous in terms of insertion loss performance at high frequencies. The insertion loss is reduced by approximately 2% compared to the low roughness OR. This is the result of the ultra-low roughness achieved by the method. The difference between the sample piece of the method of the present invention and the untreated test piece is minimal. This shows the ultra-low roughness leverage of the method of the present invention for high-frequency substrate applications.

[0139] Embodiment A. The following method steps: i) Preparing a substrate having a surface of at least one copper or copper alloy; ii) Contacting at least a portion of the surface of the copper or copper alloy with a pre-dip composition; iii) Contacting at least a portion of the surface of the copper or copper alloy with an etching solution In a method for nano-etching the surface of copper or a copper alloy, characterized in that: - The steps are carried out sequentially; - Step ii) is a non-etching step; - Step iii) is an etching step; - The pre-dip composition comprises a) A compound of formula (I)

[0140]

Chemical formula

[0141] (Wherein, X = S or S(O); R 1 ,R 2 ,R 3 ,R 4 = H, C1-C6 alkyl, OH), Its derivatives, salts, and mixtures; b) A compound of formula (II)

[0142]

Chemical formula

[0143] (wherein, X = S, S(O), S-S; R 1 , R 2 , R 3 = H, C1-C6 alkyl, OH, or R 1 + R 3 = CH=CH, R 5 = H, C1-C6 alkyl, OH, or R 3 + R 5 = CH=CH

[0144]

Chemical formula

[0145] ) its derivatives, salts, and mixtures; c) A compound (thiol or disulfide) of the structure Y-H or Y 2 [provided that Y- = [wherein, X = S,

[0146]

Chemical formula

[0147] (wherein, X = S, R 6 = COOH, C1-C6 alkyl; R 7 = H, NH 2 , C1-C6 alkyl; R 8 = COOH, SO 3 H, C1-C3 alkyl)], and d) 3-nitrobenzenesulfonic acid characterized by containing at least one sulfur-containing compound selected from the group consisting of a method.

[0148] B. At least one sulfur-containing compound is a) Thiourea [X = S; R 1 , R 2 , R 3 , R 4 = H], b) 2-aminothiazole [X = S, R1 , R 2 = H, R 3 + R 5 : -CH=CH-, 2-mercaptoimidazole [X = S, R 2 , R 5 = H, R 1 + R 3 : -CH=CH-, formamidine disulfide (dihydrochloride) (X = S-S, R 1 , R 2 , R 3 = H, R 5 =

[0149]

Chemical formula

[0150] ), formamidine sulfinic acid [X = S(O), R 1 , R 2 , R 3 = H, R 5 = OH], its derivatives, salts, and mixtures; and c) cysteine [X = SH, R 1 = H, R 2 = NH 2 , R 3 = COOH], 3,3'-dithiodipropionic acid [X = S-S, R 1 = H; R 2 = H; R 3 = COOH] The method of Embodiment A selected from the group consisting of

[0151] C. In step ii), the predip composition is an aqueous solution having a pH of -1 to 11, the method of Embodiment A or B.

[0152] D. In step iii), the etching solution is a) at least one acid; b) at least one oxidizing agent suitable for oxidizing copper; preferably, at least one oxidizing agent is selected from the group consisting of peroxides and superoxides; c) optionally, at least one halide ion source; d) at least one solvent, preferably water; e) optionally, at least one azole corrosion inhibitor; f) optionally, at least one polyalkylene compound; and g) when at least one oxidizing agent optionally contains Fe(III), at least one ferrous ion source An aqueous solution comprising or consisting of any of the preceding embodiments.

[0153] E. The following steps iv) contacting the surface of the copper or copper alloy with a post-dip solution Any of the methods of the preceding embodiments further comprising.

[0154] F. A method according to any of the preceding embodiments, characterized in that the substrate comprising the surface of the copper or copper alloy is selected from a copper foil, a copper alloy foil, a printed circuit board, an IC substrate, an interposer, a copper-coated semiconductor wafer, and a copper-clad laminate.

[0155] G. A method according to any of the preceding embodiments for creating voids on the surface of a copper or copper alloy, wherein a plurality of voids are obtuse with respect to the upper surface, and the plurality of voids have a depth of at least 50 nm and less than 500 nm.

[0156] H. A method according to embodiment G for treating an article having a surface of a copper or copper alloy, wherein the article is a patterned sample.

[0157] I. A method according to embodiment H, wherein the change in the dimensions of the pattern is less than 10% of the original value, preferably less than 7% of the original value, more preferably less than 5% of the original value, and most preferably the dimensions of the pattern do not change.

[0158] J. An embodiment I method in which the dimensional change is a line width reduction, the line width reduction is less than 10% of the original value, preferably the line width reduction is less than 7% of the original value, more preferably the line width reduction is less than 5% of the original value, and most preferably the line width reduction is 0% of the original value.

[0159] K. An article comprising a surface of copper or a copper alloy obtained by any of the methods of the preceding embodiments, having a copper surface with cavities on the copper surface, wherein the plurality of cavities are at an obtuse angle to the upper surface and the plurality of cavities have a depth of at least 50 nm and less than 500 nm.

[0160] L. An article having a copper surface according to embodiment K, wherein the article is a patterned sample.

[0161] M. An article according to embodiment L, wherein the dimensional change of the pattern is less than 10% of the original value, preferably the dimensional change of the pattern is less than 7% of the original value, more preferably the dimensional change of the pattern is less than 5% of the original value, and most preferably the dimensions of the pattern do not change.

[0162] N. An article according to embodiment M, wherein the dimensional change is a line width reduction, the line width reduction is less than 10% of the original value, preferably the line width reduction is less than 7% of the original value, more preferably the line width reduction is less than 5% of the original value, and most preferably the line width reduction is 0% of the original value.

[0163] O. Use of any of the articles of embodiments K to N in temporary adhesion applications and / or permanent adhesion applications and / or as a solder resist pretreatment and as a laser direct drilling (LDD) pretreatment.

[0164] P. Use according to embodiment O in a metal mesh touch screen.

[0165] The following non-limiting examples further illustrate the present invention.

Examples

[0166] The predip composition was prepared by dissolving all components in water or, if necessary, in a diluted acidic or alkaline solution.

[0167] The etching solution was prepared by dissolving all components in water or, if necessary, in a diluted acidic solution. The electrodeposited (ED) copper foil used in the experiments had an average particle size of 0.5 - 3 μm as determined by SEM of the electropolished samples.

[0168] The adhesion strength value (also referred to as the peel strength value) between the treated copper surface and the organic matrix was measured according to the method described in IPC - TM - 650 Test Method Manual Number 2.4.8 Revision C.

[0169] The smoothness (or roughness) of the outer surface was determined in tapping mode by a scanning atomic force microscope (Digital Instruments, NanoScope equipped with a PointProbe® from Nanosensors having a tip radius of less than 7 nm, scan size: 20×20 μm). The RSAI value (relative surface area increase) and S a (average roughness) were obtained from these measurements and are shown in each of the following examples.

[0170] Microscopic characterization of the copper surface was performed using a Carl Zeiss SMT Ltd. EVO15 - 07.05 scanning electron microscope or a Helios NanoLab 650 scanning electron microscope (SEM, both from FEI Company). Alternatively, an optical microscope (Olympus Optical Ltd., BX 60F - 3) was used if applicable.

[0171] To evaluate the line shape change (and thus the retention of the desired rectangular shape), the difference between the upper side and the bottom side was measured. The upper side - bottom side difference is the width of the upper side (width 上辺 ) and the bottom side (width 底辺) and obtained by measuring the width of each copper or copper alloy line. The top - bottom difference is obtained from the following formula: Top - bottom difference = width 上辺 - width 底辺

[0172] Therefore, a negative difference between the top and the bottom is related to copper lines mainly etched at the top, while a positive difference between the top and the bottom means that etching was dominant at the bottom of the above - mentioned copper lines. The difference between the top and the bottom of the processed copper lines should approach zero as these copper lines have a rectangular shape.

[0173] Line width reduction was obtained from measuring the size of the copper lines before and after the treatment. The smaller the above value, the better.

[0174] Etching rate was obtained by treating the copper - clad laminate for 60 seconds and measuring the mass before and after etching. The difference can be recalculated to the etching rate for 60 seconds.

[0175] In this specification, comparative examples are sometimes abbreviated as comp., and the present invention is abbreviated as inv.

[0176] Structure for screening

[0177]

Table 1A

[0178]

Table 1B

[0179]

Table 2

[0180]

Table 3

[0181] Each SEM image is shown in Fig. 2.

Claims

1. The following method steps: i) Preparing a substrate having a surface of at least one copper or copper alloy; ii) Contacting at least a part of the surface of the copper or copper alloy with a pre-dip composition; iii) Contacting at least a part of the surface of the copper or copper alloy with an etching solution In a method for nano-etching the surface of copper or a copper alloy, characterized in that: - The steps are carried out sequentially; - Step ii) is a non-etching step; - Step iii) is an etching step; - The pre-dip composition comprises a) A compound of formula (I) 【Chemical 1】 (wherein X = S or S(O), R 1 , R 2 , R 3 , R 4 = H, C1-C6 alkyl, OH), its derivatives, salts, and mixtures; b) A compound of formula (II) 【Chemical Formula 2】 (wherein X = S, S(O), S-S, R 1 , R 2 , R 3 = H, C1-C6 alkyl, OH, or R 1 + R 3 = CH=CH, R 5 = H, C1-C6 alkyl, OH, 【Chemical Formula 3】 or R 3 +R 5 =CH=CH), its derivatives, salts, and mixtures; c) Compound (thiol or disulfide) of structure Y-H or Y 2 ​ [provided that Y- = [Chemical Formula 4] (wherein X = S, R 6 = COOH, C1-C6 alkyl; R 7 = H, NH 2 、C1-C6 alkyl; R 8 = COOH, SO 3 H, C1-C3 alkyl)], and d) 3-Nitrobenzenesulfonic acid Comprising at least one sulfur-containing compound selected from the group consisting of A method characterized by this.

2. The at least one sulfur-containing compound is a) Thiourea [X = S; R 1 , R 2 , R 3 , R 4 = H], b) 2-Aminothiazole [X = S, R 1 , R 2 = H, R 3 + R 5 : -CH=CH-], 2-Mercaptoimidazole [X = S, R 2 , R 5 = H, R 1 + R 3 : -CH=CH-], Formamidine disulfide (dihydrochloride) (X = S-S, R 1 , R 2 , R 3 = H, R 5 = 【Chemical Formula 5】 ) formamidine sulfinic acid [X = S(O), R 1 , R 2 , R 3 = H, R 5 = OH], its derivatives, salts, and mixtures; and c) Cysteine [X = SH, R 1 = H, R 2 = NH 2 、R 3 = COOH], 3,3'-Dithiodipropionic acid [X = S-S, R 1 = H; R 2 = H; R 3 = COOH] Selected from the group consisting of, the method according to claim 1.

3. In step iii), the etching solution is a) At least one acid; b) At least one oxidizing agent suitable for oxidizing copper; preferably, the at least one oxidizing agent is selected from the group consisting of peroxides and superoxides; c) Optionally, at least one halide ion source; d) At least one solvent, preferably water; e) Optionally, at least one azole corrosion inhibitor; f) Optionally, at least one polyalkylene compound, and g) When the at least one oxidizing agent contains Fe(III), optionally, at least one ferrous ion source An aqueous solution comprising or consisting of these, the method according to claim 1 or 2.

4. The following step iv) Contacting the surface of the copper or copper alloy with a post-dip solution Further comprising, the method according to any one of claims 1 to 3.

5. The substrate comprising the surface of copper or a copper alloy is selected from copper foil, copper alloy foil, printed circuit board, IC substrate, interposer, copper-plated semiconductor wafer, and copper-clad laminate, the method according to any one of claims 1 to 4.

6. The method according to any one of claims 1 to 5 for creating cavities on the surface of the copper or copper alloy, A method in which a plurality of said cavities are obtuse with respect to the upper surface, and a plurality of said cavities have a depth of at least 50 nm and less than 500 nm.

7. The method according to claim 6 for treating an article having a surface of copper or a copper alloy, wherein the article is a patterned sample.

8. The method according to claim 7, wherein the dimensional change of the pattern is less than 10% of the original value, preferably the dimensional change of the pattern is less than 7% of the original value, more preferably the dimensional change of the pattern is less than 5% of the original value, and most preferably the dimensions of the pattern do not change.

9. The method according to claim 8, wherein the dimensional change is a line width reduction, the line width reduction is less than 10% of the original value, preferably the line width reduction is less than 7% of the original value, more preferably the line width reduction is less than 5% of the original value, and most preferably the line width reduction is 0% of the original value.

10. An article comprising a surface of copper or a copper alloy obtained by the method according to any one of claims 1 to 9, having a copper surface including cavities on the copper surface, wherein a plurality of said cavities are obtuse with respect to the upper surface, and a plurality of said cavities have a depth of at least 50 nm and less than 500 nm.

11. The article having a copper surface according to claim 10, wherein the article is a patterned sample.

12. The article according to claim 11, wherein the dimensional change of the pattern is less than 10% of the original value, preferably the dimensional change of the pattern is less than 7% of the original value, more preferably the dimensional change of the pattern is less than 5% of the original value, and most preferably the dimensions of the pattern do not change.

13. The article according to claim 12, wherein the dimensional change is a line width reduction, the line width reduction is less than 10% of the original value, preferably the line width reduction is less than 7% of the original value, more preferably the line width reduction is less than 5% of the original value, and most preferably the line width reduction is 0% of the original value.

14. Use of the article as defined in any one of claims 10 to 13 in temporary adhesion applications and / or in permanent adhesion applications and / or as a solder resist pretreatment and as a laser direct drilling (LDD) pretreatment.

15. Use according to claim 14 in a metal mesh touch screen.

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