Copper etching solution and application thereof

Abstract

The invention provides a copper etching solution and application thereof. The copper etching liquid comprises an inorganic acid, hydrogen peroxide, an azole compound, a halogen ion source and an amine compound, wherein the amine compound is selected from a compound shown in a formula 1 or an ammonium salt with a structural fragment shown in a formula 2. When the copper etching solution is applied to etching treatment on a chemical copper plating seed layer by a semi-additive method, the copper etching solution shows excellent differential etching capability, and has no obvious etching on the side wall of electroplating copper and the seed layer at the bottom of a copper circuit on the basis of effectively removing the seed layer between the copper circuits, so that the etching quality of the copper plating seed layer is improved. The undercut phenomenon can be prevented, the line width reduction amount is small, and the reliability degree of micronized line wiring can be obviously improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of semiconductor chemicals, and relates to a copper etching solution and application thereof. BACKGROUND

[0002] The packaging substrate is a kind of circuit board for carrying chips, which can provide support, heat dissipation and protection for the chips, and belongs to the core semiconductor packaging component. In recent years, with the development of miniaturization and multifunctionalization of electronic equipment, higher requirements are put forward for the micro-fineness and reliability of the circuit of the packaging substrate. The semi-additive method is an important method for completing micro-fineness wiring on the packaging substrate, and the core process is to form a seed layer on the surface of the insulating substrate as a conductive base by chemical copper plating, then to plate a resist layer on the surface of the seed layer, to form a resist pattern through exposure and development, to perform copper electroplating, to remove the resist layer, and finally to remove the seed layer through etching, so as to complete the wiring.

[0003] In order to obtain a relatively ideal circuit wiring, it is required that the wiring shape is not changed when the seed layer is removed, which has a high requirement for the differential etching performance of the etching solution, and it is required that the etching solution only removes the seed layer between the copper lines during etching, and does not etch the sidewall and bottom of the electroplated copper and the seed layer below the electroplated copper. However, the corrosion rate of most wet etching solutions on chemical copper is higher than that on electroplated copper, and if not controlled, lateral etching, also known as undercut, will be formed at the position where the circuit contacts the substrate. In addition, when the etching solution has too high etching solubility, the differential etching performance is weakened, and in addition to the seed layer between the copper lines, the seed layer below the electroplated copper will also be etched, resulting in a reduction in line width. For micro-fine circuits, undercut and line width reduction will seriously affect the reliability of the circuit and increase the risk of circuit separation and poor conductivity.

[0004] Therefore, how to improve the differential etching ability of the etching solution and inhibit undercut and line width reduction is a technical problem to be solved in the field. SUMMARY

[0005] The application provides a copper etching solution and application thereof. The copper etching solution of the application has excellent differential etching ability when applied to etching treatment of the chemical copper seed layer in the semi-additive method, and has no obvious etching on the sidewall of the electroplated copper and the seed layer at the bottom of the copper circuit on the basis of effectively removing the seed layer between the copper lines, can prevent the undercut phenomenon and has a small amount of line width reduction, and can significantly improve the reliability of micro-fine circuit wiring.

[0006] The application provides a copper etching solution, which comprises: an inorganic acid, hydrogen peroxide, an azole compound, a halogen ion source, and an amine compound.

[0007] The amine compound is selected from a compound shown in formula 1 or an ammonium salt having a structural fragment shown in formula 2.

[0008]

[0009] In formula 1 and formula 2, R1, R2, R3, R4 are each independently selected from C1-C4 alkyl; A represents substituted or unsubstituted alkylene having 1-8 carbon atoms in the main chain, and adjacent alkylene is connected by L1 selected from one or more of single bond, -S-, -NHC(O)NH-, -O-, -C(O)O-, -NH-, -C(O)-, the substituent of substituted alkylene is selected from one or more of C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio, hydroxyl, -NR5R6, wherein R5 and R6 are each independently selected from H or C1-C4 alkyl.

[0010] In an alternative embodiment, the ammonium salt having the structural fragment shown in formula 2 is selected from polyquaternary ammonium salt shown in formula 3;

[0011]

[0012] In formula 3, X - is selected from chloride ion, bromide ion or hydrogen sulfate ion; L2 is selected from single bond or -O-, n1 and n2 are each independently selected from an integer between 1-4.

[0013] In an alternative embodiment, R1, R2, R3, R4 are each independently selected from methyl or ethyl.

[0014] In an alternative embodiment, A is selected from R7-L1-R8, wherein R7 and R8 are each independently selected from C1-C4 alkylene, and L1 is selected from single bond, -NHC(O)NH- or -O-.

[0015] In an alternative embodiment, the compound shown in formula 1 is selected from N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N,N',N'-tetramethyl-1,3-propanediamine, 1,3-bis[3-(dimethylamino)propyl]urea, N,N,N',N'-tetramethyl-1,2-diaminopropane, N,N,N',N'-tetramethylmalonamide, 3,3'-iminobis(N,N-dimethylpropylamine), N,N,N',N'-tetramethyl-L-tartaric amide or N,N,N',N'-tetramethyl-D-tartaric amide.

[0016] In an alternative embodiment, the polyquaternary ammonium salt shown in formula 3 has a molecular weight of 1000-300000.

[0017] In an alternative embodiment, the polyquaternary ammonium salt shown in formula 3 is selected from polyquaternary ammonium salt-2, hexadimethrine bromide, hexadimethrine chloride or polydichloroethyl ether tetramethyl ethylenediamine.

[0018] In an alternative embodiment, the ammonium salt having the structural fragment of Formula 2 is selected from polyquaternium-6, hexamethonium chloride, or hexamethonium bromide.

[0019] In an alternative embodiment, the inorganic acid has a concentration of 1-100 g / L.

[0020] In an alternative embodiment, the hydrogen peroxide has a concentration of 1-100 g / L.

[0021] In an alternative embodiment, the azole compound has a concentration of 0.1-10 g / L.

[0022] In an alternative embodiment, the halide ion source has a mass content of 0.1 ppm-50 ppm.

[0023] In an alternative embodiment, the amine compound has a mass content of 1 ppm-1000 ppm.

[0024] In an alternative embodiment, the inorganic acid is selected from one or more of sulfuric acid, nitric acid, or phosphoric acid.

[0025] In an alternative embodiment, the azole compound is selected from one or more of 1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1-methyltetrazole, 5-mercapto-1H-tetrazole, 5-(ethylthio)-1H-tetrazole, 1-phenyl-5-mercapto-1H-tetrazole, 1-cyclohexyl-5-mercapto-1H-tetrazole, 5,5'-bi-1H-tetrazole, and an ammonium salt, a sodium salt, or a potassium salt of the above compounds.

[0026] In an alternative embodiment, the halide ion source is selected from one or more of sodium chloride, potassium chloride, sodium bromide, or potassium bromide.

[0027] In an alternative embodiment, the copper etching solution further comprises a copper ion source.

[0028] In an alternative embodiment, the copper ion source has a concentration of 0.1-50 g / L.

[0029] The present application also provides an etching method for a printed circuit board, the printed circuit board comprising a substrate and copper circuits distributed on the substrate, and a seed layer formed by electroless copper plating between adjacent copper circuits, wherein the etching method comprises wet etching the seed layer using the copper etching solution as described above.

[0030] The application provides a copper etching solution, which comprises inorganic acid, hydrogen peroxide, an azole compound, a halogen ion source and an amine compound, wherein the amine compound is selected from a compound shown in formula 1 or an ammonium salt having a structural fragment shown in formula 2. When the copper etching solution is applied to etching treatment of a chemical copper plating seed layer in a semi-addition method, insoluble complexes are formed through the joint action of hydrogen peroxide, inorganic acid and the azole compound, and the amine compound with a specific structure is adsorbed on the sidewall and bottom corner of the copper circuit, so that a dense protective film is formed on the sidewall and bottom corner through double adsorption, the etching solution is prevented from entering, undercut and line width reduction are avoided, excellent differential etching capacity is exhibited, the seed layer between copper circuits is effectively removed, the seed layer on the sidewall of the electroplated copper and the bottom of the copper circuit is not obviously etched, the reliability of the circuit is improved, and the copper etching solution is especially suitable for wiring of a microcircuit. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 1;

[0032] Figure 2 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 2;

[0033] Figure 3 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 3;

[0034] Figure 4 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 4;

[0035] Figure 5 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 5;

[0036] Figure 6 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 6;

[0037] Figure 7 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 7;

[0038] Figure 8 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 8;

[0039] Figure 9 SEM-FIB image of the interface between a circuit and a substrate in a packaging substrate etched by the copper etching solution in Example 9;

[0040] Figure 10 SEM-FIB image of the interface between the circuit and the substrate in the packaging substrate etched by the copper etching solution of Comparative Example 1;

[0041] Figure 11 SEM-FIB image of the interface between the circuit and the substrate in the packaging substrate etched by the copper etching solution of Comparative Example 2;

[0042] Figure 12 SEM-FIB image of the interface between the circuit and the substrate in the packaging substrate etched by the copper etching solution of Comparative Example 3;

[0043] Figure 13 SEM-FIB image of the interface between the circuit and the substrate in the packaging substrate etched by the copper etching solution of Comparative Example 4;

[0044] Figure 14 SEM-FIB image of the interface between the circuit and the substrate in the packaging substrate etched by the copper etching solution of Comparative Example 4;

[0045] Figure 15 Energy spectrum of the copper circuit in the packaging substrate etched by the copper etching solution of Example 3. DETAILED DESCRIPTION

[0046] In order to make the purposes, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without any creative work under the premise that the present application falls within the scope of protection.

[0047] The present application provides a copper etching solution, comprising: inorganic acid, hydrogen peroxide, azole compound, halogen ion source and amine compound;

[0048] The amine compound is selected from the compound shown in Formula 1 or the ammonium salt having the structural fragment shown in Formula 2;

[0049]

[0050] In Formula 1 and Formula 2, R1, R2, R3, R4 are each independently selected from C1-C4 alkyl group; A represents substituted or unsubstituted alkylene group having a main chain of 1 to 8 carbon atoms, and adjacent alkylene groups are connected by L1 selected from one or more of a single bond, -S-, -NHC(O)NH-, -O-, -C(O)O-, -NH-, -C(O)-, and the substituent of the substituted alkylene group is selected from one or more of C1-C4 alkyl group, C1-C4 alkoxy group, C1-C4 alkylthio group, hydroxyl group, -NR5R6, wherein R5 and R6 are each independently selected from H or C1-C4 alkyl group.

[0051] It should be noted that the copper etching solution of the present application is not only used for etching of copper element, but also can be used for etching of copper alloy, and the copper etching solution of the present application refers to the etching solution used for etching of pure copper or copper alloy.

[0052] In the present application, "C1-C4 alkyl group" refers to a straight chain or branched chain saturated hydrocarbon group containing 1 to 4 carbon atoms, which can be exemplified by methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, t-butyl group, sec-butyl group, isobutyl group, etc.

[0053] The main chain in "substituted or unsubstituted alkylene group having a main chain of 1 to 8 carbon atoms" refers to a chain including both "-NR1R2" and "-NR1R2" groups, and the 1 to 8 carbon atoms refer to the number of carbon atoms in the main chain, and when the alkylene group is further connected with a substituent, the number of carbon atoms in the substituent is not included in the number of carbon atoms in the main chain.

[0054] "Alkylene group" is a divalent group formed by removing one hydrogen from an alkyl group.

[0055] Unsubstituted alkylene group includes, but is not limited to, methylene group (-CH2-), ethylene group (-CH2CH2-), propylene group (-CH2CH2-), butylene group (-CH2CH2CH2CH2-), pentylene group (-CH2CH2CH2CH2CH2-), hexylene group (-CH2CH2CH2CH2CH2CH2-), etc.

[0056] "C1-C4 alkoxy group" refers to a group formed by connecting a straight chain or branched chain alkyl group containing 1 to 4 carbon atoms with an oxygen atom, which can be exemplified by methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, t-butoxy group, sec-butoxy group, isobutoxy group, etc.

[0057] "C1-C4 alkylthio group" refers to a group formed by connecting a straight chain or branched chain alkyl group containing 1 to 4 carbon atoms with a sulfur atom, which can be exemplified by methylthio group, ethylthio group, n-propylthio group, isopropylthio group, n-butylthio group, t-butylthio group, sec-butylthio group, isobutylthio group, etc.

[0058] "NR5R6" means a group formed by substituting amino with R5and R6, for example, -NHCH3, -N(CH3)2, -NHCH2CH3, -N(CH2CH3)2, etc.

[0059] "connected by L1between adjacent alkylene groups" means that one or more L1, preferably one or two, are inserted between the alkylene groups of the main chain. When L1is selected from a single bond, it means that there is no other group between the adjacent alkylene groups, and L1only serves as a connection.

[0060] " " represents the binding site with other fragments or groups.

[0061] In this application, the structural fragment shown in formula 2 is essentially an ammonium salt formed by quaternization of the tertiary amine group of the compound shown in formula 1.

[0062] The copper etching solution of the present application shows excellent differential etching ability when applied to the etching treatment of electroless copper seed layer in the semi-additive process, effectively removes the seed layer between copper lines, and has no significant etching on the sidewall of electroplated copper and the seed layer at the bottom of the copper line, which can prevent undercut phenomenon and has less line width reduction, and can significantly improve the reliability of micro-fine line layout.

[0063] The inventor analyzes the reasons for the above excellent effects as follows:

[0064] On the one hand, the hydrogen peroxide in the copper etching solution of the present application can oxidize copper to form copper oxide as an oxidizing agent, and the inorganic acid provides an acidic environment for the etching solution system. Copper oxide is easy to dissolve and change into copper ions under acidic conditions, thereby completing the etching of copper. The divalent copper ions or monovalent copper ions produced during the etching process can be coordinated with azole compounds to form insoluble complexes and adsorbed on the sidewall of the electroplated copper in the substrate and the sidewall of the electroless copper seed layer below the electroplated copper.

[0065] In another aspect, the specific amine compound in the copper etching solution of the present application is a chain monomer with two tertiary amines or quaternary ammonium, or a chain polymer with quaternary ammonium structure in the main chain. In the micro adsorption scenario, the tertiary amine or quaternary ammonium N has strong adsorption ability to the copper metal surface or the copper azole compound surface due to its orbital electron structure, and the A chain between the two Ns will be attached to the metal surface and will be more preferentially adsorbed at the lattice dislocation and grain boundary of the copper metal surface due to the influence of van der Waals force. Since the adsorption of N on the copper surface is not selective, the adsorption effect of conventional amine compounds cannot cause the adsorption difference between the copper surface and the grain boundary / dislocation. In addition, if the A chain is too long, or an aromatic ring structure is added to the A chain, or the length of the substituent branch on the A chain is too long, it will affect the paving structure of the molecule on the grain boundary, which is not conducive to the preferential adsorption of the amine compound at the lattice dislocation and grain boundary. Since the crystal grains of the electroless copper seed layer are smaller than those of the electroplated copper, the lattice dislocation and grain boundary are more, so the adsorption ability of the amine compound of the present application on the surface / sidewall of the electroless copper is stronger than that of the general amine compound.

[0066] Through the above two aspects of adsorption, a dense protective film can be formed on the electroplated copper sidewall and the seed layer sidewall below, preventing the entry of the etching solution, thereby avoiding undercutting and line width reduction, and increasing the reliability of the circuit.

[0067] In a preferred embodiment, the ammonium salt having the structural fragment shown in Formula 2 is selected from a polyquaternary ammonium salt shown in Formula 3;

[0068]

[0069] In Formula 3, X is selected from chloride ion, bromide ion or hydrogen sulfate ion; L2 is selected from a single bond or -O-, n1 and n2 are each an integer between 1 and 4; R1, R2, R3, R4 and A have the same definition range as the compound shown in Formula 1, which will not be repeated here. - In Formula 3, X is selected from chloride ion, bromide ion or hydrogen sulfate ion; L2 is selected from a single bond or -O-, n1 and n2 are each an integer between 1 and 4; R1, R2, R3, R4 and A have the same definition range as the compound shown in Formula 1, which will not be repeated here.

[0070] In a specific embodiment, the polyquaternary ammonium salt shown in Formula 3 is obtained by copolymerization of the compound shown in Formula 1 and the compound shown in Formula 4;

[0071]

[0072] In Formula 4, X, L2, n1 and n2 have the same definition as Formula 3, which will not be repeated here.

[0073] In a preferred embodiment, R1, R2, R3 and R4 are each independently selected from methyl or ethyl.

[0074] In a preferred embodiment, A is selected from R7-L1-R8, wherein R7and R8are each independently selected from C1-C4 alkylene, and L1is selected from a single bond, -NHC(O)NH-, or -O-.

[0075] In the present application, the compound of formula 1 can be specifically selected from N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N,N',N'-tetramethyl-1,3-propanediamine, 1,3-bis[3-(dimethylamino)propyl]urea, N,N,N',N'-tetramethyl-1,2-diaminopropane, N,N,N',N'-tetramethylmalonamide, 3,3'-iminobis(N,N-dimethylpropylamine), N,N,N',N'-tetramethyl-L-tartaric amide, or N,N,N',N'-tetramethyl-D-tartaric amide.

[0076] The compound of formula 1 of the above kind, when applied as an additive to the copper etching solution of the present application, has a suitable etching rate and excellent differential etching ability, can effectively inhibit the occurrence of undercut phenomenon, and has a small line width reduction.

[0077] The structure of the compound of formula 1 of the above kind can be specifically selected as shown below:

[0078]

[0079] In the present application, the compound of formula 4 can be specifically selected from 1,4-dibromobutane, 1,4-dichlorobutane, 1,6-dibromohexane, 1,6-dichlorohexane bis(2-bromoethyl) ether, bis(2-chloroethyl) ether, etc.

[0080] In the present application, the etching characteristics of the copper etching solution can be adjusted by adjusting the molecular weight of the polyquaternary ammonium salt. Specifically, when the molecular weight of the polyquaternary ammonium salt is too large, the dispersibility of the molecule is poor, it is easy to coagulate into a mass in the solution, it is difficult to spread on the surface, it is difficult to effectively form a protective film, and a too large molecular weight will cause it to be difficult to dissolve in the etching solution, it is easy to form emulsion droplets in the solution, and it is also difficult to play an adsorption role.

[0081] In a preferred embodiment, the molecular weight of the polyquaternary ammonium salt of formula 3 is 1000-300000.

[0082] In a preferred embodiment, the polyquaternary ammonium salt of formula 3 is selected from polyquaternary ammonium salt-2, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, or polydichloroethyl ether tetramethyl ethylenediamine.

[0083] The polyquaternary ammonium salt of the above kind, when applied as an additive to the copper etching of the present application, not only has a moderate etching rate, but also can excellent inhibit undercutting and maintain a small line width reduction.

[0084] Polyquaternium-2 is a copolymer of 1,3-bis[3-(dimethylamino)propyl]urea and bis(2-chloroethyl) ether, and its structure is shown as follows:

[0085]

[0086] Hexadimethrine bromide is a copolymer of N,N,N',N'-tetramethyl-1,3-propanediamine and 1,6-dibromohexane, and its structure is shown as follows:

[0087]

[0088] Hexadimethrine chloride is a copolymer of N,N,N',N'-tetramethyl-1,3-propanediamine and 1,6-dichlorohexane, and its structure is shown as follows:

[0089]

[0090] Polydichloroethyl ether tetramethyl ethylene diamine is a copolymer of tetramethyl ethylene diamine and bis(2-chloroethyl) ether, and its structure is shown as follows:

[0091]

[0092] In a preferred embodiment, the ammonium salt having the structural fragment shown in Formula 2 is selected from polyquaternium-6, hexamethonium chloride or hexamethonium bromide.

[0093] Polyquaternium-6 is a homopolymer of dimethyldiallylammonium chloride, and its structure is shown as follows:

[0094]

[0095] The structures of hexamethonium chloride and hexamethonium bromide are shown as follows, respectively:

[0096]

[0097] In a preferred embodiment, the concentration of inorganic acid in the copper etching solution of the present application is 1-100 g / L;

[0098] and / or, the concentration of hydrogen peroxide is 1-100 g / L;

[0099] and / or, the concentration of azole compound is 0.1-10 g / L;

[0100] and / or, the mass content of halide ion source is 0.1 ppm-50 ppm;

[0101] and / or, the mass content of amine compound is 1 ppm-1000 ppm.

[0102] In addition to the above components, the remaining components in the copper etching solution can be deionized water.

[0103] When the inorganic acid, hydrogen peroxide, azole compound, halide ion source and amine compound in the copper etching solution are within the above mass concentration or mass content range, it is beneficial to maintain a stable and suitable etching rate and the ability to differentiate etching.

[0104] The type of inorganic acid in the present application is not specifically limited, which can be selected from conventional inorganic acids in the art, including but not limited to one or more of sulfuric acid, nitric acid or phosphoric acid.

[0105] In the present application, the azole compound in the copper etching solution can be selected from triazole compounds or tetrazole compounds, and more preferably tetrazole compounds. Tetrazole compounds have more nitrogen atoms than triazole compounds, which can provide more lone pair electrons for coordination with copper ions, thereby forming a more stable insoluble protective film.

[0106] In a preferred embodiment, the azole compound in the present application is selected from one or more of 1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1-methyltetrazole, 5-mercapto-1H-tetrazole, 5-(ethylthio)-1H-tetrazole, 1-phenyl-5-mercapto-1H-tetrazole, 1-cyclohexyl-5-mercapto-1H-tetrazole, 5,5'-bi-1H-tetrazole, and ammonium salt, sodium salt or potassium salt of the above compounds.

[0107] In the present application, the halide ion source refers to a soluble inorganic salt with halide anions, and more preferably a soluble inorganic salt with chloride anions and bromide anions, including but not limited to one or more of sodium chloride, potassium chloride, sodium bromide, potassium bromide.

[0108] In a specific embodiment, the copper etching solution of the present application further comprises a copper ion source.

[0109] The type of copper ion source in the present application is not specifically limited, which can be a conventional soluble inorganic salt with copper ions in the art, including but not limited to one or more of copper sulfate, copper chloride, copper bromide.

[0110] The divalent copper ions in the copper ion source can undergo a reverse disproportionation reaction with elemental copper in the packaging substrate to obtain monovalent cuprous ions, which is beneficial to the etching process. At the same time, since the etching reaction product is divalent copper ions, the introduction of divalent copper ions in the etching solution helps to maintain the stability of the etching rate.

[0111] Further, the concentration of the copper ion source in the copper etching solution is 0.1-50 g / L (calculated by the mass of copper). Within the above concentration range, both the etching speed and the stability of the dissolved copper can be considered.

[0112] The application does not specially limit the preparation method of the above copper etching solution. The copper etching solution can be formed by dissolving each component in the copper etching solution in deionized water according to a specific concentration.

[0113] The application also provides an etching method for a printed circuit board, which comprises a substrate and copper circuits distributed on the substrate, and seed layers formed by electroless copper plating between adjacent copper circuits. The etching method comprises: wet etching the seed layers by using the above copper etching solution.

[0114] The application does not limit the specific mode of wet etching, which can be a wet etching mode commonly used in the art, such as spraying or immersion.

[0115] Further, the copper etching solution with a temperature of 20-40 °C is preferably used in the above wet etching process.

[0116] The etching method of the application can effectively remove the seed layer while avoiding etching the side wall and the bottom corner of the copper circuit to the greatest extent, thereby effectively avoiding undercutting and line width reduction and ensuring the reliability of the copper circuit.

[0117] The copper etching solution, the preparation method and the application thereof provided by the application are described in detail below through specific examples.

[0118] Unless otherwise specified, the materials or reagents used in the present application can be purchased or prepared by methods known in the art.

[0119] The molecular weight of the polymer raw material in the copper etching solution of the following examples and comparative examples is as follows:

[0120] Polyquaternary ammonium salt-6 Mw 15000;

[0121] Polyquaternary ammonium salt-2 Mw 18000;

[0122] Hexadimethrine bromide Mw 4000-6000;

[0123] Polydichloroethyl ether tetramethyl ethylenediamine Mw 4000;

[0124] Polyethyleneimine Mw 10000;

[0125] Polyacrylamide Mn 40000;

[0126] Polyethylene glycol Mn 2000.

[0127] Example 1

[0128] The present example provides a copper etching solution, which is prepared by dissolving and mixing sulfuric acid, hydrogen peroxide, 5-amino tetrazole, polyquaternary ammonium salt-6, copper sulfate pentahydrate and sodium chloride in deionized water, wherein the content of each component of the prepared copper etching solution is as follows:

[0129] sulfuric acid, 40 g / L;

[0130] hydrogen peroxide, 20 g / L;

[0131] 5-amino tetrazole, 0.5 g / L;

[0132] polyquaternary ammonium salt-6, 10 ppm;

[0133] copper sulfate pentahydrate, 30 g / L;

[0134] sodium chloride, 0.5 ppm;

[0135] deionized water, the balance.

[0136] Example 2

[0137] The present example provides a copper etching solution, which is prepared by dissolving and mixing sulfuric acid, hydrogen peroxide, 5-amino tetrazole, polyquaternary ammonium salt-6, copper sulfate pentahydrate and sodium chloride in deionized water, wherein the content of each component of the prepared copper etching solution is as follows:

[0138] Example 3

[0139] The present example provides a copper etching solution, which is prepared by dissolving and mixing sulfuric acid, hydrogen peroxide, 5-amino tetrazole, polyquaternary ammonium salt-6, copper sulfate pentahydrate and sodium chloride in deionized water, wherein the content of each component of the prepared copper etching solution is as follows:

[0140] Example 4

[0141] The present example provides a copper etching solution, which is prepared by dissolving and mixing sulfuric acid, hydrogen peroxide, 5-amino tetrazole, polyquaternary ammonium salt-6, copper sulfate pentahydrate and sodium chloride in deionized water, wherein the content of each component of the prepared copper etching solution is as follows:

[0142] Example 5

[0143] The present example provides a copper etching solution, which is prepared by dissolving and mixing sulfuric acid, hydrogen peroxide, 5-amino tetrazole, polyquaternary ammonium salt-6, copper sulfate pentahydrate and sodium chloride in deionized water, wherein the content of each component of the prepared copper etching solution is as follows:

[0144] Example 6

[0145] The embodiment provides a copper etching solution, the composition and the preparation method of which are basically consistent with those of the embodiment 2, except that the "N,N,N',N'-tetramethyl-1,6-hexanediamine, 500 ppm" is replaced by "N,N,N',N'-tetramethyl-1,6-hexanediamine, 2 g / L".

[0146] Embodiment 7

[0147] The embodiment provides a copper etching solution, the composition and the preparation method of which are basically consistent with those of the embodiment 1, except that the "polyquaternary salt-6, 10 ppm" is replaced by "polydichloroethyl ether tetramethyl ethylenediamine, 25 ppm".

[0148] Embodiment 8

[0149] The embodiment provides a copper etching solution, the composition and the preparation method of which are basically consistent with those of the embodiment 1, except that the "polyquaternary salt-6, 10 ppm" is replaced by "1,3-bis[3-(dimethylamino)propyl]urea, 200 ppm".

[0150] Embodiment 9

[0151] The embodiment provides a copper etching solution, the composition and the preparation method of which are basically consistent with those of the embodiment 1, except that the "polyquaternary salt-6, 10 ppm" is replaced by "N,N,N',N'-tetramethyl-D-tartaric amide, 200 ppm".

[0152] Comparative example 1

[0153] The comparative example provides a copper etching solution, the composition and the preparation method of which are basically consistent with those of the embodiment 1, except that the polyquaternary salt-6 is not added in the copper etching solution.

[0154] Comparative example 2

[0155] The comparative example provides a copper etching solution, the composition and the preparation method of which are basically consistent with those of the embodiment 1, except that the "polyquaternary salt-6, 10 ppm" is replaced by "polyethylene imine, 10 ppm";

[0156] The structural formula of the polyethylene imine is as follows:

[0157]

[0158] Comparative example 3

[0159] The comparative example provides a copper etching solution, the composition and the preparation method of which are basically consistent with those of the embodiment 1, except that the "polyquaternary salt-6, 10 ppm" is replaced by "polyacrylamide, 20 ppm";

[0160] The structural formula of the polyacrylamide is shown below:

[0161]

[0162] Comparative Example 4

[0163] This comparative example provides a copper etching solution, the composition and preparation method of which are basically the same as those of Example 1, except that "polyquaternary salt-6, 10 ppm" is replaced by "polyethylene glycol, 20 ppm";

[0164] The structural formula of the polyethylene glycol is shown below:

[0165]

[0166] Comparative Example 5

[0167] This comparative example provides a copper etching solution, the composition and preparation method of which are basically the same as those of Example 1, except that "polyquaternary salt-6, 10 ppm" is replaced by "dodecyl trimethyl ammonium bisulfate, 20 ppm";

[0168] The structural formula of the dodecyl trimethyl ammonium bisulfate is shown below:

[0169]

[0170] Application Example

[0171] The copper etching solution of the above examples and comparative examples is used for etching treatment of a packaging substrate, and the specific steps are as follows:

[0172] 1) A packaging substrate (Shenzhen Xingsen Express Circuit Co., Ltd.) without a seed layer etching process is prepared, the line width and line spacing of which are both 14 μm, the seed layer is a chemical copper layer with a thickness of 1 μm, and the substrate material is GX92 (Japan Ajinomoto Co., Inc.);

[0173] 2) A horizontal spray etching machine with a fan-shaped nozzle sprayer is used to spray the copper etching solution to a copper-clad substrate (Shenzhen Fuxiang Technology Co., Ltd.) with an electroplated copper surface at a pressure of 0.1 MPa and a temperature of 30°C for 2-3 min, and then water washing and drying are performed. The etching rate of the electroplated copper is calculated by the method of difference weight. The same method is used to etch a copper-clad substrate (Shenzhen Fuxiang Technology Co., Ltd.) with a chemical copper surface of about 1-1.2 μm for 30 s, and then water washing and drying are performed. The etching rate of the chemical copper is calculated by the method of difference weight;

[0174] The etching rates of different examples and comparative examples are listed in Table 1.

[0175] 3) Calculate the time required for the etching thickness of the electroplated copper to be 0.6 μm based on the etching rate obtained in step 2). Then, adjust the moving speed of the horizontal conveyor belt to perform etching on the packaging substrate prepared in step 1) within this time, wash it with water, and blow it dry.

[0176] Test case

[0177] The following performance tests were performed on the packaging substrates after etching for the above application examples:

[0178] 1. Bottom cut

[0179] Test method: After etching, the packaging substrate was cut into 2cm×2cm pieces, and the morphology of the circuit was observed using a scanning electron microscope. The interface between the circuit and the substrate was exposed by cutting the circuit area with a focused ion beam, and the undercut after etching was observed.

[0180] Figures 1 to 14 The images shown are, in order, SEM-FIB images of the interface between the circuitry and the substrate in the packaging substrate after etching with copper etching solutions of Examples 1-9 and Comparative Examples 1-5.

[0181] from Figures 1 to 9 The cross-sections of the copper circuits on the packaging substrates after copper etching solution treatment in Examples 1-9 show that, except for Example 6, the chemical copper seed layer under the electroplated copper circuits is completely preserved, no obvious chemical copper etching marks are found on the sidewalls, the circuits are straight, and the circuits are firmly bonded to the substrate. However, in Example 6, the copper circuit interface of the packaging substrate after copper etching solution treatment shows a more serious undercut phenomenon at the sidewalls of the circuits, indicating that the excessive addition of the specific amine compound is also not conducive to suppressing undercut.

[0182] from Figure 10 , Figure 12 , Figure 14 The cross-sections of the substrates treated with the copper etching solutions of Comparative Examples 1, 3, and 5 show that after treatment with the copper etching solutions of Comparative Examples 1, 3, and 5, the chemical copper seed layer under the electroplated copper lines was completely removed, and a clear cross-section appeared between the lines and the substrate, indicating that the lines were detached from the substrate.

[0183] from Figure 11 and Figure 13 The cross-sections of the substrates treated with copper etching solutions in Comparative Examples 2 and 4 show that after treatment with copper etching solutions in Comparative Examples 2 and 4, the chemical copper seed layer under the electroplated copper lines was partially removed, with only a small amount of chemical copper seed layer remaining in the middle, resulting in severe undercutting. Lines with such a structure are prone to detachment from the substrate after being subjected to external force.

[0184] The undercut length test results of the above embodiments and comparative examples are shown in Table 1.

[0185] The copper lines etched by the copper etching solution of Example 3 were analyzed by scanning electron microscope and X-ray energy dispersive spectrometer (SEM-EDS), Figure 15 The energy spectrum between the copper lines of the packaging substrate etched by the copper etching solution of Example 3 is shown in Figure 2. Figure 15 As can be seen from Figure 2, the chemical copper between the copper lines is completely removed, and there is no residual copper between the lines.

[0186] 2. Line width reduction amount

[0187] Test method: The top image of the copper lines was taken by an optical microscope (Olympus, Japan), four different line widths were tested, and the average value was taken as the line width value. The line width of the same packaging substrate before and after etching was measured, and the difference between the two was taken as the line width reduction amount. The test results are shown in Table 1.

[0188] For easy comparison, the differences in components and the contents of the differences in components in the copper etching solution between Examples 2-9 and Comparative Examples 1-5 and Example 1 are also listed in Table 1.

[0189] Table 1

[0190]

[0191]

[0192] From Table 1, the following conclusions can be drawn:

[0193] 1) From the comparison of Examples 1-5, 7-9 and Comparative Examples 1-5, it can be seen that the addition of the amine compound with a specific structure as an additive in the copper etching solution can make the etching process have a suitable etching rate, while also showing excellent differential etching ability, effectively removing the chemical copper seed layer between the lines, while also having a small undercut value and line width reduction amount.

[0194] 2) From the comparison of Example 2 and Example 6, it can be seen that when the amount of the amine compound additive with a specific structure added in the copper etching solution is too much, the undercut phenomenon at the sidewall of the line will be more serious.

[0195] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the above examples have been described in detail, those skilled in the art should understand that the technical solutions described in the above examples can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A copper etching liquid, characterized by, Comprise: an inorganic acid, hydrogen peroxide, an azole compound, a halide ion source, and an amine compound; the amine compound is selected from a compound of Formula 1 or an ammonium salt having a structural fragment of Formula 2; in Formula 1 and Formula 2, R1, R2, R3, R4 are each independently selected from C1-C4 alkyl; A represents a substituted or unsubstituted alkylene group having a main chain of 1-8 carbon atoms, and adjacent alkylene groups are connected by L1, which is selected from one or more of a single bond, -S-, -NHC(O)NH-, -O-, -C(O)O-, -NH-, -C(O)-, and the substituents of the substituted alkylene group are selected from one or more of C1-C4 alkyl, C1-C4 alkoxy, C1-C4 alkylthio, hydroxyl, -NR5R6, wherein R5 and R6 are each independently selected from H or C1-C4 alkyl.

2. The copper etching liquid according to claim 1, wherein the ammonium salt having a structural fragment of Formula 2 is selected from a polyquaternary ammonium salt of Formula 3; In formula 3, X - is selected from chloride, bromide or hydrogen sulfate; L2is selected from a single bond or -O-, and n1and n2are each selected from an integer between 1 and 4.

3. The copper etching liquid according to claim 1 or 2, characterized by, R1, R2, R3, R4 are each independently selected from methyl or ethyl.

4. The copper etching liquid according to any one of claims 1 to 3, characterized by, A is selected from R7-L1-R8, wherein R7 and R8 are each independently selected from C1-C4 alkylene, and L1 is selected from a single bond, -NHC(O)NH- or -O-.

5. The copper etching liquid according to claim 1, wherein the compound of Formula 1 is selected from N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N,N',N'-tetramethyl-1,3-propanediamine, 1,3-bis[3-(dimethylamino)propyl]urea, N,N,N',N'-tetramethyl-1,2-diaminopropane, N,N,N',N'-tetramethylmalonamide, 3,3'-iminobis(N,N-dimethylpropylamine), N,N,N',N'-tetramethyl-L-tartaric amide, or N,N,N',N'-tetramethyl-L-tartaric amide.

6. The copper etching liquid according to claim 2, wherein the polyquaternary ammonium salt of Formula 3 has a molecular weight of 1000-300000.

7. The copper etching liquid according to claim 2 or 6, wherein the polyquaternary ammonium salt of Formula 3 is selected from polyquaternary ammonium salt-2, hexadimethrine bromide, hexadimethrine chloride, or polydichlorodimethyl ether tetramethyl ethylenediamine.

8. The copper etching liquid according to claim 1, wherein the ammonium salt having a structural fragment of Formula 2 is selected from polyquaternary ammonium salt-6, hexamethonium dichloride, or hexamethonium bromide.

9. The copper etching liquid according to claim 1, wherein the concentration of the inorganic acid is 1-100 g / L; and / or, the concentration of the hydrogen peroxide is 1-100 g / L; and / or, the concentration of the azole compound is 0.1-10 g / L; and / or, the mass content of the halide ion source is 0.1 ppm-50 ppm; and / or, the mass content of the amine compound is 1 ppm-1000 ppm.

10. The copper etching liquid according to claim 1 or 9, wherein the inorganic acid is selected from one or more of sulfuric acid, nitric acid, or phosphoric acid.

11. The copper etching liquid according to claim 1 or 9, wherein the azole compound is selected from one or more of 1H-tetrazole, 5-amino-1H-tetrazole, 5-methyl-1H-tetrazole, 5-phenyl-1H-tetrazole, 5-amino-1-methyltetrazole, 5-mercapto-1H-tetrazole, 5-(ethylthio)-1H-tetrazole, 1-phenyl-5-mercapto-1H-tetrazole, 1-cyclohexyl-5-mercapto-1H-tetrazole, 5,5'-bi-1H-tetrazole, and ammonium salts, sodium salts, or potassium salts of the above compounds.

12. The copper etching liquid according to claim 1 or 9, wherein The halogen ion source is selected from one or more of sodium chloride, potassium chloride, sodium bromide, and potassium bromide.

13. The copper etching liquid according to any one of claims 1 to 12, wherein The copper etching solution further comprises a copper ion source.

14. The copper etching liquid according to claim 13, wherein The concentration of the copper ion source is 0.1-50 g / L.

15. An etching method of a printed wiring board comprising a substrate and copper wiring distributed on the substrate with a seed layer formed by electroless copper plating between adjacent copper wirings, characterized by, The etching method comprises wet etching the seed layer using the copper etching solution according to any one of claims 1-14.

Images