Tin or tin alloy electroplating composition containing an inhibitor

Abstract

The present invention provides an aqueous composition comprising tin ions and at least one compound of formula I, wherein: X 1 、X 2 are independently selected from linear or branched C1-C 12 alkanediyl, which may optionally be interrupted by O or S; R 11 is a monovalent group of formula -(O-CH2-CHR 41 ) m -OR 42 ; R 12 、R 13 、R 14 are independently selected from H, R 11 and R 40 ; R 15 is selected from H, R 11 、R 40 and -X 4 -N(R 21 )2; X 4 is selected from (a) linear or branched C1-C 12 alkanediyl and (b) a divalent group of formula -(O-CH2-CHR 41 ) o -; R 21 is selected from R 11 and R 40 ; R 40 is linear or branched C1-C 20 alkyl; R 41 is selected from H and linear or branched C1-C5 alkyl; R 42 is selected from H and linear or branched C1-C 20 alkyl, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl; n is an integer from 1 to 6, 2m is an integer from 2 to 250, and o is an integer from 1 to 250.

Description

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a tin or tin alloy electroplating composition comprising an inhibitor, its use, and a method for electroplating tin or a tin alloy.

[0003] Metals and metal alloys are crucial commercially, especially in the electronics industry where they are commonly used as electrical contacts, final finishes, and solders.

[0004] Lead-free solders such as tin, tin-silver, tin-copper, tin-bismuth, tin-silver-copper, etc. are common metals used in solders. These solders are typically deposited on semiconductor substrates by means of a metal electroplating bath.

[0005] Typical tin plating solutions contain dissolved tin ions, water, an acidic electrolyte such as methanesulfonic acid in an amount sufficient to confer conductivity to the bath, an antioxidant, and proprietary additives to improve the plating uniformity and the quality of the metal deposit in terms of surface roughness and pore formation. Such additives typically include inhibitors (commonly also referred to as surfactants) and grain refiners, among others.

[0006] Certain applications of lead-free solder electroplating face challenges in the electronics industry. For example, when used as a coating on copper pillars, a relatively small amount of lead-free solder, such as tin or tin-silver solder, is deposited on the tops of the copper pillars. When electroplating such a small amount of solder, it is generally difficult to electroplate a highly uniform solder composition on the tops of the individual pillars within the mold and on the wafer. Using known solder electroplating baths also produces deposits with a relatively rough surface topography.

[0007] US4135991 and GB1567235 disclose a bath for electroplating tin and / or lead comprising a specific alkoxylated amine brightener, the brightener comprising polyoxyalkylene and C8-C 22 or C 12 -C 18 fatty acid alkyl.

[0008] EP2141261A2 discloses a tin electroplating bath comprising N,N-dipolyoxyalkylene-N-alkylamine, amine oxide, or a mixture thereof, especially those comprising an alkyl group having 6-28 carbon atoms.

[0009] To provide a tin deposit with an acceptable morphology and substantially free of porosity, US 2015 / 122661A1 proposes a tin electroplating composition comprising a source of tin ions, an acidic electrolyte, a specific first grain refiner in an amount of 0.0001 - 0.045 g / l, an α,β-unsaturated aliphatic carbonyl compound as a second grain refiner in an amount of 0.005 - 0.75 g / l, and a nonionic surfactant. The nonionic surfactant can be a tetrafunctional polyether derived from the addition of different alkylene oxides to ethylenediamine, preferably derived from propylene oxide and ethylene oxide, among many other surfactants. The alkyleneoxy structural moieties in the compound can be in a block, alternating, or random arrangement. The molar ratio of x:y in Formulas 3 and 4 is generally 10:90 - 90:10, preferably 10:90 - 80:20.

[0010] The need to fit more functional units into ever-smaller spaces has driven the integrated circuit industry to the bump approach for encapsulating interconnects. A second driver is to maximize the number of input / output connections in a given area. As bump diameter and bump pitch decrease, connection density can increase. These arrays are realized using copper bumps or μ-columns electroplated with a tin or tin alloy solder cap thereon. To ensure that each bump can contact the tin or tin alloy solder within the wafer, bumps with a smooth surface and uniform deposition height are required.

[0011] However, there is still a need in the electronics industry for a pure tin or tin alloy electroplating bath that results in solder deposits with good morphology, particularly low roughness, and improved height uniformity (also known as coplanarity (COP)).

[0012] An object of the present invention is to provide a tin electroplating composition that provides tin or tin alloy deposits showing good morphology, particularly low roughness, and that can fill features on the micron scale with substantially no formation of defects such as, but not limited to, porosity. Another object of the present invention is to provide a tin or tin alloy electroplating bath that provides uniform and flat tin or tin alloy deposits, particularly for structures having a width of 1 - 200 microns. Summary of the Invention

[0014] The present invention provides an aqueous composition comprising tin ions and at least one compound of Formula I:

[0015]

[0016] Wherein:

[0017] X 1 、X 2 Independently selected from straight-chain or branched C1 - C 12 alkanediyl, which may optionally be spaced with O or S,

[0018] R11 is a monovalent group of formula -(O-CH2-CHR 41 ) m -OR 42 ,

[0019] R 12 , R 13 , R 14 are independently selected from H, R 11 and R 40 ;

[0020] R 15 is selected from H, R 11 , R 40 and -X 4 -N(R 21 )2,

[0021] X 4 is selected from (a) a linear or branched C1-C 12 alkanediyl and (b) a divalent group of formula -(O-CH2-CHR 41 ) o -

[0022] R 21 is selected from R 11 and R 40 ,

[0023] R 40 is a linear or branched C1-C 20 alkyl,

[0024] R 41 is selected from H and linear or branched C1-C5 alkyl,

[0025] R 42 is selected from H and linear or branched C1-C 20 alkyl, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl,

[0026] n is an integer from 1 to 6,

[0027] m is an integer from 2 to 250, and

[0028] o is an integer from 1 to 250.

[0029] The inhibitors of the present invention are particularly suitable for filling recessed structures with pore sizes from 500 nm to 500 μm, especially those with pore sizes from 1 to 200 μm.

[0030] Due to the inhibitory effect of the inhibitor, dendrite growth is inhibited, and smaller grain sizes and smoother surfaces are obtained, and the coplanarity of electroplated tin or tin alloy solder bumps is improved.

[0031] The present invention further relates to the use of a tin or tin alloy electroplating bath comprising a composition as defined herein for depositing tin or a tin alloy on a substrate comprising structures with pore sizes from 500 nm to 500 μm.

[0032] The present invention further relates to a method for depositing a tin or tin alloy layer on a substrate, comprising:

[0033] a) bringing a composition as defined herein into contact with the substrate, and

[0034] b) applying a current to the substrate for a time sufficient to deposit a tin or tin alloy layer on the substrate,

[0035] wherein the substrate comprises structures with pore sizes from 500 nm to 500 μm and the deposition is carried out to fill these structures. Brief Description of the Drawings

[0037] Figure 1 Shows a SEM photograph of the electroplated tin bumps of Comparative Example 2.1;

[0038] Figure 2 Shows a SEM photograph of the electroplated tin bumps of Comparative Example 2.2;

[0039] Figure 3 Shows a SEM photograph of the electroplated tin bumps of Example 2.3;

[0040] Figure 4 Shows a SEM photograph of the electroplated tin bumps of Example 2.4;

[0041] Figure 5 Shows a SEM photograph of the electroplated tin bumps of Example 2.5;

[0042] Figure 6 Shows a SEM photograph of the electroplated tin bumps of Example 2.6;

[0043] Figure 7 Shows a SEM photograph of the electroplated tin bumps of Example 2.7;

[0044] Figure 8 Shows a SEM photograph of the electroplated tin bumps of Example 2.8. Detailed Description of the Invention

[0046] The Inhibitor of the Present Invention

[0047] The tin and tin alloy electroplating compositions of the present invention containing at least one inhibitor as described hereinafter have shown extraordinary performance in filling microscale structures. As used herein, "inhibitor" is an additive that increases the overpotential during tin electrodeposition. Here, the terms "surfactant" and "inhibitor" are used synonymously because the inhibitors described herein are also surface-active substances.

[0048] In addition to tin ions, the aqueous compositions of the present invention contain at least one compound of formula I as further described hereinafter:

[0049]

[0050] The compound of formula I can be prepared by reacting a polyamine initiator with one or more C2-C6 alkylene oxides to form each amine-based inhibitor.

[0051] Generally, n can be an integer from 1 to 6. Preferably, n is an integer from 1 to 4, and most preferably, n is 1 or 2.

[0052] X 1 and X 2 are divalent spacer groups in the polyamine initiator. It can be independently selected from linear or branched C1-C 12 alkanediyl. The alkanediyl spacer group is unsubstituted, but may be optionally spaced with O or S. X 1 and X 2 can be the same or different, preferably the same. In a first preferred embodiment, X 1 and X 2 are C1-C6 alkanediyl, more preferably C1-C4 alkanediyl, and most preferably methanediyl, ethanediyl or propanediyl. In a second preferred embodiment, a heteroatom is present and X 1 and X 2 can be -(CHR 41 ) q -[Q-(CHR 41 ) r s -, where Q is selected from O or S, and q + r·s is the number of C atoms in the spacer group. A spacer group with Q = O and q = r = 1 or 2 is particularly preferred.

[0053] R 11 is a monovalent group of the formula -(O-CH2-CHR 41 ) m -OR, where m is an integer from 2 to 250, preferably from 3 to 120, and most preferably from 10 to 65. Since R 11 can be prepared by polyalkoxylation of one or more alkylene oxides, it is also referred to herein as "polyalkylene oxide" or "polyoxyalkylene". R 41 ​Selected from H and linear or branched C1-C5 alkyl groups, preferably selected from H and linear or branched C1-C3 alkyl groups, more preferably selected from H, methyl, ethyl, and n-propyl, and most preferably selected from H or methyl. R 42 Selected from H and linear or branched C1-C 20 alkyl groups, which may optionally be substituted with hydroxyl, alkoxy, or alkoxycarbonyl groups, preferably selected from H and linear or branched C1-C 10 alkyl groups, more preferably selected from H and methyl, ethyl, propyl, or butyl, and most preferably H.

[0054] Generally, R 12 、R 13 、R 14 are independently selected from H, R 11 and R 40 , preferably selected from R 11 and R 40 , and most preferably selected from R 11 .

[0055] R 40 is a linear or branched C1-C 20 alkyl group. Preferably, R 40 is a C1-C 10 alkyl group, even more preferably a C1-C6 alkyl group, and most preferably methyl, ethyl, or propyl.

[0056] R 42 is a linear or branched C1-C 20 alkyl group, which may optionally be substituted with hydroxyl, alkoxy, or alkoxycarbonyl groups. Preferably, R 42 is an unsubstituted linear or branched C1-C 20 alkyl group.

[0057] Generally, R 15 is selected from H, R 11 、R 40 and -X 4 -N(R 21 )2, where R 21 is selected from R 11 and R 40 , preferably selected from R 11 .

[0058] In a preferred embodiment, R 15 is selected from R 11 and -X 4 -N(R 11 )2. In another preferred embodiment, R 15 is selected from R 40 and -X 4 -N(R 40 )2.

[0059] In one embodiment, X 4 is a straight-chain or branched C1-C 12 alkanediyl. Preferably, X 4 is a C1-C6 alkanediyl, more preferably methylenediyl, ethanediyl, propanediyl or butanediyl, and most preferably methylenediyl or ethanediyl.

[0060] In another embodiment, X 4 is a divalent group of a C2-C6 polyoxyalkylene (hereinafter also referred to as a polyoxyalkylene group) selected from the formula -(O-CH2-CHR 41 )o-. Here, o can be an integer from 1 to 250, preferably 2 to 120, and most preferably 5 to 65. The C2-C6 polyoxyalkylene can be prepared from the one or more corresponding alkylene oxides. Preferably, the at least one C2-C6 polyoxyalkylene is selected from polyoxyethylene (prepared from ethylene oxide), polyoxypropylene (prepared from propylene oxide) and polyoxybutylene (prepared from butylene oxide). More preferably, the polyoxyalkylene in X 4 is a copolymer of ethylene oxide and at least one other C3-C6 alkylene oxide. The other alkylene oxide is preferably selected from propylene oxide and 1,2-butylene oxide or any isomer thereof. In another preferred embodiment, the C3-C4 alkylene oxide is selected from propylene oxide (PO). In this case, the EO / PO copolymer side chain is generated from the starting molecule. The copolymer of ethylene oxide and at least one other alkylene oxide can have a random, block, alternating or any other arrangement.

[0061] As used herein, "random" means that the comonomers are polymerized from a mixture and are thus arranged statistically depending on their copolymerization parameters.

[0062] As used herein, "block" means that the comonomers are polymerized successively with each other to form blocks of the respective comonomers in any predetermined order. For example, for EO and propylene oxide (PO) comonomers, the block can be, but is not limited to: -EO x -PO y , -PO x -EO y , -EO x -PO y -EO z , -PO x -EO y -PO z etc. Preferred block types of alkylene oxides are -PO x -EO y and -EO x -PO y -EO z , where x is from 2 to 300, y is from 2 to 300, and z is from 2 to 300.

[0063] In a preferred embodiment, a block - PO copolymer containing terminal ethylene oxide blocks is used x -EO y or -EO x -PO y -EO z copolymer, wherein the PO units can be replaced by other C4 - C6 alkylene oxides.

[0064] If a copolymer of ethylene oxide (EO) and other C3 - C4 alkylene oxides is used, the EO content is usually 3 - 95 wt%. Preferably, the EO content is 5 - 80 wt%, more preferably 5 - 60 wt%, even more preferably less than 50 wt%, even more preferably less than 40 wt%, even more preferably 5 - 40 wt%, even more preferably 5 - 30 wt%, even more preferably 6 - 25 wt%, and most preferably 8 - 20 wt%.

[0065] Generally, the molecular weight M of the inhibitor w can be about 500 - about 30000 g / mol, preferably 2000 - 15000 g / mol. In one embodiment, the molecular weight M of the inhibitor w is about 500 - about 8000 g / mol, most preferably about 1500 - about 3500 g / mol. In another embodiment, the molecular weight M of the inhibitor w is about 5000 - about 20000 g / mol, especially about 6000 - about 15000 g / mol.

[0066] In a first preferred embodiment, a compound of formula I is used, where n is 1, 2 or 3, most preferably 1 or 2; and R 12 、R 13 、R 14 and R 15 are independently selected from C2 - C6 polyoxyalkylene R 11 . Such compounds can be prepared starting from symmetric dialkylenetriamines, trialkylenetetramines, tetraalkylenepentamines, such as but not limited to diethylenetriamine, triethylenetetramine, dipropylenetriamine, tripropylenetetramine, methyldiethylenetriamine, dimethyltriethylenetetramine, etc.

[0067] In a second preferred embodiment, a compound of formula I is used, where n is 1, 2 or 3, most preferably 1 or 2; R 12 、R 13 、R 14 are independently selected from C2 - C6 polyoxyalkylene R 11 ; and R 15 is selected from X 4 -N(R 11) 2. In this way, more branched polyoxyalkylene inhibitors are obtained. Such compounds can be prepared by starting with a branched amine initiator, such as but not limited to triaminoethylamine, etc.

[0068] In a third preferred embodiment, n is 1, 2 or 3, most preferably 1 or 2; R 12 , R 13 and R 14 are selected from C2-C6 polyoxyalkylene R 11 ; and R 15 is selected from R 40 and -X 4 -N(R 40 )2. In this way, linear or branched inhibitors are obtained which, in addition to the polyoxyalkylene side chains, also contain one or more alkyl substituents. Such compounds can be prepared by starting with a linear amine in which the secondary amino group is alkyl-substituted as described above, or from a branched amine in which one or more amino groups are alkyl-substituted (such as but not limited to trialkylaminoethylamine, etc.).

[0069] In a fourth preferred embodiment, n is 1, 2 or 3, preferably 1 or 2, most preferably 1; R 12 is selected from R 11 ; R 13 and R 14 are selected from R 40 ; and R 15 is selected from R 21 . Such compounds can be prepared by starting with a symmetrically alkyl-substituted diethylene triamine or triethylene tetramine, such as but not limited to N,N-dimethyldiethylenetriamine, N,N,N-trimethyldiethylenetriamine, etc.

[0070] In a fifth preferred embodiment, n is 1, 2 or 3, preferably 1 or 2, most preferably 1; and R 13 is selected from R 11 , and at least one of R 12 and R 14 is selected from R 40 ; and R 15 is selected from R 21 . Such compounds can be prepared by starting with an asymmetric diethylene triamine or triethylene tetramine, such as but not limited to 1-N-methyldiethylenetriamine, 1,3-N-dimethyldiethylenetriamine, etc.

[0071] Particularly preferred embodiments of the inhibitor of formula I are those in which:

[0072] (a) X 1 and X 2 are ethanediyl or propanediyl, R 11 , R 12 , R13 , R 14 and R 15 are polyoxyalkylene groups,

[0073] specifically oxyethylene - co - oxypropylene polymers,

[0074] (b) X 1 and X 2 are ethanediyl or propanediyl, and R 11 , R 12 , R 13 and R 14 are polyoxyalkylene groups, specifically oxyethylene - co - oxypropylene polymers, and R 15 is a C1 - C6 alkyl group or a polyoxyalkylene - substituted C1 - C6 alkyl group, and

[0075] (c) X 1 and X 2 are ethanediyl or propanediyl, and R 11 , R 12 , R 13 and R 14 are polyoxyalkylene groups, specifically oxyethylene - co - oxypropylene polymers, and R 15 is a C1 - C6 amine, which is further substituted by a polyoxyalkylene group, specifically an oxyethylene - co - oxypropylene polymer.

[0076] Those skilled in the art should be aware that more than one inhibitor can be used. Preferably, only one or more compounds of the present invention are used as inhibitors in the electroplating bath composition.

[0077] Various additives can generally be used in the bath to provide the desired surface finish for the electroplated tin or tin - alloy bumps. Usually, more than one additive is used, and each additive performs a desired function. Advantageously, the electroplating bath can contain one or more of a surfactant, a grain refiner, a complexing agent (in the case of alloy deposition), an antioxidant, and mixtures thereof. Most preferably, in addition to the inhibitor of the present invention, the electroplating bath contains a leveling agent and optionally a grain refiner. Other additives can also be suitably used in the electroplating bath of the present invention.

[0078] Other inhibitors or surfactants

[0079] Any other nonionic surfactant can be used in the composition of the present invention. Generally, the average molecular weight of the nonionic surfactant is 200-100,000, preferably 500-50,000, more preferably 500-25,000, still more preferably 750-15,000. Such nonionic surfactants are usually present in the electrolyte composition at a concentration of 1-10,000 ppm, preferably 5-10,000 ppm, based on the weight of the composition. Preferred alkylene oxide compounds include polyalkylene glycols, such as but not limited to alkylene oxide adducts of organic compounds having at least one hydroxyl group and 20 carbon atoms or less, and tetrafunctional polyethers derived from the addition of different alkylene oxides to low molecular weight polyamine compounds.

[0080] Preferred polyalkylene glycols are polyethylene glycol and polypropylene glycol. Such polyalkylene glycols are generally commercially available from various sources and can be used without further purification. Blocked polyalkylene glycols can also be suitably used, in which one or more of the terminal hydrogens are replaced by hydrocarbon groups. Examples of suitable polyalkylene glycols are polyalkylene glycols of the formula R-O-(CXYCX'Y'O) n R', where R and R' are independently selected from H, C2-C 20 alkyl and C6-C 20 aryl; X, Y, X' and Y' are each independently selected from hydrogen, alkyl such as methyl, ethyl or propyl, aryl such as phenyl, or aralkyl such as benzyl; and n is an integer from 5-100,000. Usually one or more of X, Y, X' and Y' are hydrogen.

[0081] The EO:PO weight ratio of suitable EO / PO copolymers is generally 10:90-90:10, preferably 10:90-80:20. The average molecular weight of such EO / PO copolymers is preferably 750-15,000. Such EO / PO copolymers are commercially available from various sources, for example those available from BASF under the trade name "PLURONIC".

[0082] Suitable alkylene oxide condensation products of organic compounds having at least one hydroxyl group and 20 or fewer carbon atoms include those of aliphatic hydrocarbons having 1-7 carbon atoms, unsubstituted aromatic compounds or alkylated aromatic compounds having 6 or fewer carbons in the alkyl structural moiety, such as those disclosed in US 5,174,887. The aliphatic alcohols can be saturated or unsaturated. Suitable aromatic compounds are those having at most 2 aromatic rings. Before derivatization with ethylene oxide, the aromatic alcohols have at most 20 carbon atoms. Such aliphatic and aromatic alcohols can be further substituted, for example by sulfate or sulfonate groups.

[0083] Leveling agent

[0084] One or more leveling agents may be present in the tin or tin alloy electroplating bath.

[0085] The leveling agent category is a linear or branched polyimidazolium compound containing the inclusive L1 structural unit:

[0086]

[0087] Generally, R 1 and R 2 may be H atoms or organic groups having 1 - 20 carbon atoms. Such groups may be branched or unbranched, or contain functional groups that can, for example, contribute to further crosslinking of the polyimidazolium compound. Preferably, R 1 and R 2 are each independently a hydrogen atom or a hydrocarbon group having 1 - 6 carbon atoms. Most preferably, R 1 and R 2 are H atoms.

[0088] Generally, R 3 may be a H atom or an organic group having 1 - 20 carbon atoms. Preferably, R 3 is a H atom or methyl, ethyl or propyl. Most preferably, R 3 is a H atom.

[0089] Generally, X 1 may be a linear, branched or cyclic aliphatic bivalent group selected from C4 - C 20 alkanediyl, which may contain one or more continuations of the polyimidazolium compound through branching.

[0090] As used herein, "one or more continuations of the polyimidazolium compound through branching" means that each spacer group X 1 contains one or more, preferably one or two groups from which the polyimidazole branches at its origin. Preferably, X 1 does not contain any continuation of the polyimidazolium compound through branching, i.e., the polyimidazolium compound is a linear polymer.

[0091] In a first embodiment, X 1 is C4 - C 14 alkanediyl, most preferably C4 - C 12 alkanediyl, which may be unsubstituted or substituted by OR 4 、NR 4 2 and SR 4 wherein R 4 is a C1 - C4 alkyl group. In a particular embodiment, X 1 is a pure hydrocarbon group containing no functional groups.

[0092] Particularly preferred group X 1Selected from linear or branched butanediyl, pentanediyl, hexanediyl, heptanediyl, octanediyl, nonanediyl, decanediyl, undecanediyl and dodecanediyl, which may be unsubstituted or substituted by OR 4 、NR 4 Substituted. Particularly preferred group X 1 Is selected from linear butanediyl, hexanediyl and octanediyl.

[0093] In a second embodiment, the group X 1 May be a cycloalkanediyl of the following formula:

[0094]

[0095] Wherein:

[0096] X 2 Is independently selected from C1-C4 alkanediyl, which may be interrupted by one or two selected from O and NR 4 ; and X 3 Is independently selected from (a) a chemical bond or (b) C1-C4 alkanediyl, which may be interrupted by O or NR 4 , wherein R 4 Is a C1-C4 alkyl group.

[0097] As used herein, "chemical bond" means that there is no corresponding structural moiety, but adjacent structural moieties are bridged to form a direct chemical bond between these adjacent structural moieties. For example, if the structural moiety Y in X-Y-Z is a chemical bond, then the adjacent structural moieties X and Z together form the group X-Z.

[0098] X 2 Or X 3 Or X 2 And X 3 Both may contain one or more continuations of the imidazolium compound through branching, preferably only X 2 May contain such a continuation of the imidazolium compound through branching.

[0099] In this second embodiment, most preferably, one X 2 Is selected from methanediyl and the other X 2 Is selected from propanediyl, or both X 2 Are selected from ethanediyl. Particularly preferably, the group X 1 Is selected from isophorone diamine, dicyclohexylmethanediamine and methylcyclohexylamine (MDACH).

[0100] In a third embodiment, X 1 May be a (hetero) aralkyl diyl selected from Y 2 -Y 1 -Y 2 . Here, Y 1can be C5-C 20 aryl, and Y 2 can independently be selected from linear or branched C1-C6 alkanediyls. Also herein, Y 1 and Y 2 both can contain one or more continuations through branching of the imidazolium compound.

[0101] Preferred group Y 1 is selected from phenyl, naphthyl, pyridyl, pyrimidinyl, and furyl, most preferably phenyl. Preferred group Y 2 is selected from linear or branched C1-C4 alkanediyls, preferably selected from methanediyl, ethanediyl, 1,3-propanediyl, and 1,4-butanediyl.

[0102] Organic group X 1 can contain not only carbon and hydrogen, but also heteroatoms, such as oxygen, nitrogen, sulfur, or halogen, for example in the form of functional groups, such as hydroxyl, ether, amide, aromatic heterocycle, primary amino, secondary amino, or tertiary amino, or imino.

[0103] In particular, organic group X 1 can be a hydrocarbylene group which can be substituted or interrupted by functional groups which contain heteroatoms, in particular ether groups. If substituted, X 1 preferably does not contain any hydroxyl groups.

[0104] n can generally be an integer from 2 to about 5000, preferably from about 5 to about 3000, even more preferably from about 8 to about 1000, even more preferably from about 10 to about 300, even more preferably from about 15 to about 250, and most preferably from about 25 to about 150.

[0105] The mass average molecular weight M of the additive w can generally be 500 - 1,000,000 g / mol, preferably 1000 - 500,000 g / mol, more preferably 1500 - 100,000 g / mol, even more preferably 2,000 - 50,000 g / mol, even more preferably 3,000 - 40,000 g / mol, and most preferably 5,000 - 25,000 g / mol.

[0106] Preferably, the at least one additive contains a counterion Y o- , where o is a positive integer selected such that the additive is overall electrically neutral. Preferably, o is 1, 2, or 3. Most preferably, the counterion Y o- is selected from chloride, sulfate, methanesulfonate, or acetate.

[0107] Preferably, the number average molecular weight M of the polymeric imidazolium compound determined by gel permeation chromatography nGreater than 500 g / mol.

[0108] Preferably, the polymeric imidazolium compound may comprise more than 80% by weight of the structural unit of formula L1.

[0109] More details and alternatives are described respectively in unpublished European patent application 17173987.3, patent publication WO2016 / 020216 and international patent application PCT / EP2017 / 050054, which are incorporated herein by reference.

[0110] Other suitable leveling agents include, but are not limited to: polyaminoamides and their derivatives; polyalkanolamines and their derivatives; polyethyleneimines and their derivatives; quaternized polyethyleneimines; polyglycine; poly(allylamine); polyaniline; polyureas; polyacrylamides; poly(melamine-co-formaldehyde); reaction products of amines with epichlorohydrin; reaction products of amines, epichlorohydrin and polyalkylene oxides; reaction products of amines with polyepoxides; polyvinylpyridines; polyvinylimidazoles; polyvinylpyrrolidones or their copolymers; aniline black; pentamethyl pararosaniline hydrohalide; hexamethyl pararosaniline hydrohalide; or compounds containing the formula N-R-S functional group, where R is a substituted alkyl group, an unsubstituted alkyl group, a substituted aryl group or an unsubstituted aryl group. Generally, the alkyl group is a C1-C6 alkyl group, preferably a C1-C4 alkyl group. Generally, the aryl group includes C6-C 20 aryl group, preferably C6-C 12 aryl group. Such aryl groups may further include heteroatoms such as sulfur, nitrogen and oxygen. Preferably, the aryl group is a phenyl group or a naphthyl group. Compounds containing the formula N-R-S functional group are generally known, are usually commercially available, and can be used without further purification.

[0111] In such compounds containing the N-R-S functional group, sulfur ("S") and / or nitrogen ("N") may be linked to the compound by a single bond or a double bond. When sulfur is linked to the compound by a single bond, sulfur has other substituents such as, but not limited to, hydrogen, C1-C 12 alkyl group, C2-C 12 alkenyl group, C6-C 20 aryl group, C1-C 12 alkylthio group, C2-C 12 alkenylthio group, C6-C 20 arylthio group, etc. Similarly, nitrogen has one or more substituents such as, but not limited to, hydrogen, C1-C 12 alkyl group, C2-C 12 alkenyl group, C7-C 10 aryl group, etc. The N-R-S functional group may be acyclic or cyclic. Compounds containing a cyclic N-R-S functional group include those having nitrogen or sulfur or both nitrogen and sulfur in the ring system.

[0112] The other leveling agent is a triethanolamine condensate as described in the unpublished international patent application PCT / EP2009 / 066581.

[0113] Generally, the total amount of the leveling agent in the electroplating bath is 0.5 - 10000 ppm, based on the total weight of the electroplating bath. The leveling agent of the present invention is generally used in an amount of about 100 - about 10000 ppm based on the total weight of the electroplating bath, but more or less amount can be used.

[0114] Grain refiner

[0115] The tin or tin alloy electroplating bath may further contain a grain refiner. The grain refiner may be selected from compounds of formula G1 or G2:

[0116]

[0117] where each R 1 is independently a C1 - C6 alkyl group, a C1 - C6 alkoxy group, a hydroxyl group or a halogen; R 2 and R 3 are independently selected from H and C1 - C6 alkyl groups; R 4 is H, OH, a C1 - C6 alkyl group or a C1 - C6 alkoxy group; m is an integer from 0 to 2; each R 5 is independently a C1 - C6 alkyl group; each R 6 is independently selected from H, OH, a C1 - C6 alkyl group or a C1 - C6 alkoxy group; n is 1 or 2; and p is 0, 1 or 2.

[0118] Preferably, each R 1 is independently a C1 - C6 alkyl group, a C1 - C3 alkoxy group or a hydroxyl group, more preferably a C1 - C4 alkyl group, a C1 - C2 alkoxy group or a hydroxyl group. Preferably, R 2 and R 3 are independently selected from H and C1 - C3 alkyl groups, more preferably H and methyl. Preferably, R 4 is H, OH, a C1 - C4 alkyl group or a C1 - C4 alkoxy group, more preferably H, OH or a C1 - C4 alkyl group. Preferably, R 5 is a C1 - C4 alkyl group, more preferably a C1 - C3 alkyl group. Each R 6 is preferably selected from H, OH or a C1 - C6 alkyl group, more preferably H, OH or a C1 - C3 alkyl group, still more preferably H or OH. Preferably, m is 0 or 1, more preferably, m is 0. Preferably, n is 1. Preferably, p is 0 or 1, more preferably, p is 0. A mixture of the first grain refiners can be used, such as a mixture of two different grain refiners of formula 1, two different grain refiners of formula 2, or a mixture of a grain refiner of formula 1 and a grain refiner of formula 2.

[0119] Exemplary compounds that can be used as the grain refiner include, but are not limited to, cinnamic acid, cinnamaldehyde, benzalacetone, picolinic acid, pyridine dicarboxylic acid, pyridinecarboxaldehyde, pyridine dialdehyde, or mixtures thereof. Preferred grain refiners include benzalacetone, 4-methoxybenzaldehyde, benzyl pyridine-3-carboxylate, and 1,10-phenanthroline.

[0120] Other grain refiners can be selected from α,β-unsaturated aliphatic carbonyl compounds. Suitable α,β-unsaturated aliphatic carbonyl compounds include, but are not limited to, α,β-unsaturated carboxylic acids, α,β-unsaturated carboxylic acid esters, α,β-unsaturated amides, and α,β-unsaturated aldehydes. Preferably, such grain refiners are selected from α,β-unsaturated carboxylic acids, α,β-unsaturated carboxylic acid esters, and α,β-unsaturated aldehydes, and more preferably α,β-unsaturated carboxylic acids and α,β-unsaturated aldehydes. Exemplary α,β-unsaturated aliphatic carbonyl compounds include (meth)acrylic acid, crotonic acid, C1-C6 alkyl (meth)acrylates, (meth)acrylamide, C1-C6 alkyl crotonates, crotonamide, crotonaldehyde, (meth)acrolein, or mixtures thereof. Preferred α,β-unsaturated aliphatic carbonyl compounds are (meth)acrylic acid, crotonic acid, crotonaldehyde, (meth)acrolein, or mixtures thereof.

[0121] In one embodiment, the grain refiner can be present in the electroplating bath in an amount of 0.0001 - 0.045 g / l. Preferably, the grain refiner is present in an amount of 0.0001 - 0.04 g / l, more preferably in an amount of 0.0001 - 0.035 g / l, and still more preferably in an amount of 0.0001 - 0.03 g / l. Compounds that can be used as the first grain refiner are generally commercially available from various sources and can be used as received or can be further purified.

[0122] In another more preferred embodiment, the tin or tin alloy electroplating composition contains a single grain refiner, more preferably a single grain refiner that is not an α,β-unsaturated aliphatic carbonyl compound, and most preferably is substantially free or completely free of grain refiners. It has surprisingly been found that, especially for recessed structures with filled hole sizes less than 50 μm, no grain refiner needs to be used, but in the absence of any grain refiner, the inhibitor gives good coplanarity.

[0123] The compositions of the present invention can optionally include other additives such as antioxidants, organic solvents, complexing agents, and mixtures thereof.

[0124] Antioxidant

[0125] Antioxidants can optionally be added to the compositions of the present invention to help keep the tin in a soluble, divalent state. Preferably, one or more antioxidants are used in the compositions of the present invention. Exemplary antioxidants include, but are not limited to, hydroquinone, and hydroxylated and / or alkoxylated aromatic compounds, including sulfonic acid derivatives of such aromatic compounds, preferably: hydroquinone; methylhydroquinone; resorcinol; catechol; 1,2,3-trihydroxybenzene; 1,2-dihydroxybenzene-4-sulfonic acid; 1,2-dihydroxybenzene-3,5-disulfonic acid; 1,4-dihydroxybenzene-2-sulfonic acid; 1,4-dihydroxybenzene-2,5-disulfonic acid; 2,4-dihydroxybenzenesulfonic acid; and p-methoxyphenol. Such antioxidants are disclosed in US 4,871,429. Other suitable antioxidants or reducing agents include, but are not limited to, vanadium compounds such as vanadyl acetylacetonate, vanadium triacetylacetonate, vanadium halides, vanadium oxyhalides, vanadium alkoxides, and vanadyl alkoxides. The concentration of such reducing agents is well known to those skilled in the art, but is typically 0.1 - 10 g / l, more preferably 1 - 5 g / l. Such antioxidants are generally commercially available from various sources.

[0126] Complexing agent

[0127] The tin or tin alloy electroplating bath may further comprise a complexing agent for complexing tin and / or any other metal present in the composition. A typical complexing agent is 3,6-dithia-1,8-octanediol.

[0128] Typical complexing agents are polyoxymonocarboxylic acids, polycarboxylic acids, aminocarboxylic acids, lactone compounds, and their salts.

[0129] Other complexing agents are the organic sulfur compounds disclosed in US 7628903, JP 4296358B2, EP 0854206A, and US 8980077B2, such as thiourea, thiols, or thioethers.

[0130] Electrolyte

[0131] Generally, as used herein, "aqueous" means that the plating composition of the present invention contains a solvent that contains at least 50% water. Preferably, "aqueous" means that the major portion of the composition is water, more preferably 90% of the solvent is water, and most preferably the solvent consists essentially of water. Any type of water can be used, such as distilled water, deionized, or tap water.

[0132] Tin

[0133] The tin ion source can be any compound that can release a sufficient amount of metal ions to be deposited in the electroplating bath, i.e., a compound that is at least partially soluble in the electroplating bath. Preferably, the metal ion source is soluble in the electroplating bath. Suitable metal ion sources are metal salts, including but not limited to metal sulfates, metal halides, metal acetates, metal nitrates, metal fluoroborates, metal alkyl sulfonates, metal aryl sulfonates, metal aminosulfonates, metal gluconates, etc.

[0134] The metal ion source can be present in any amount sufficient to provide enough metal ions for electroplating on the substrate in the present invention. When the metal is only tin, the tin salt is usually present in the electroplating solution in an amount of about 1 - about 300 g / l. In a preferred embodiment, the electroplating solution is lead-free, i.e., it contains 1 wt%, more preferably less than 0.5 wt%, still more preferably less than 0.2 wt%, and even more preferably no lead. In another preferred embodiment, the electroplating solution is substantially copper-free, i.e., it contains 1 wt%, more preferably less than 0.1 wt%, still more preferably less than 0.01 wt%, and even more preferably no copper.

[0135] Alloy metal

[0136] Optionally, the electroplating bath of the present invention may contain one or more alloy metal ions. Suitable alloy metals include but are not limited to silver, gold, copper, bismuth, indium, zinc, antimony, manganese, and mixtures thereof. Preferred alloy metals are silver, copper, bismuth, indium, and mixtures thereof, and more preferably silver. Any bath-soluble salt of the alloy metal can be suitably used as the alloy metal ion source. Examples of such alloy metal salts include but are not limited to: metal oxides; metal halides; metal fluoroborates; metal sulfates; metal alkanesulfonates, such as metal methanesulfonates, metal ethanesulfonates, and metal propanesulfonates; metal arylsulfonates, such as metal phenylsulfonates, metal toluenesulfonates, and metal phenolsulfonates; metal carboxylates, such as metal gluconates and metal acetates, etc. Preferred alloy metal salts are metal sulfates; metal alkanesulfonates; and metal arylsulfonates. When one alloy metal is added to the composition of the present invention, a binary alloy deposit is obtained. When two, three, or more different alloy metals are added to the composition of the present invention, ternary, quaternary, or higher-order alloy deposits are obtained. The amount of such alloy metals used in the composition of the present invention will depend on the specific tin alloy desired. The selection of this amount of alloy metal is within the ability of those skilled in the art. It should be known to those skilled in the art that when using certain alloy metals such as silver, additional complexing agents may be required. Such complexing agents (or complexes) are well known in the art and can be used in any suitable amount to obtain the desired tin alloy composition.

[0137] The electroplating composition of the present invention is suitable for depositing a tin-containing layer, which can be a pure tin layer or a tin alloy layer. Exemplary tin alloy layers include, but are not limited to, tin-silver, tin-copper, tin-indium, tin-bismuth, tin-silver-copper, tin-silver-copper-antimony, tin-silver-copper-manganese, tin-silver-bismuth, tin-silver-indium, tin-silver-zinc-copper, and tin-silver-indium-bismuth. Preferably, the electroplating composition of the present invention deposits pure tin, tin-silver, tin-silver-copper, tin-indium, tin-silver-bismuth, tin-silver-indium, and tin-silver-indium-bismuth, more preferably pure tin, tin-silver, or tin-copper.

[0138] As measured by atomic absorption spectrometry (AAS), X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS), the alloy deposited from the electroplating bath of the present invention contains from 0.01 to 99.99 wt% of tin, based on the weight of the alloy, and from 99.99 to 0.01 wt% of one or more alloying metals. Preferably, the tin-silver alloy deposited using the present invention contains 90 - 99.99 wt% of tin and 0.01 - 10 wt% of silver and any other alloying metals. More preferably, the tin-silver alloy deposit contains 95 - 99.9 wt% of tin and 0.1 - 5 wt% of silver and any other alloying metals. The tin-silver alloy is the preferred tin alloy deposit and preferably contains 90 - 99.9 wt% of tin and 10 - 0.1 wt% of silver. More preferably, the tin-silver alloy deposit contains 95 - 99.9 wt% of tin and 5 - 0.1 wt% of silver. For many applications, the eutectic composition of the alloy can be used. The alloy deposited according to the present invention is substantially free of lead, i.e., it contains 1 wt%, more preferably less than 0.5 wt%, still more preferably less than 0.2 wt% of lead, and even more preferably is lead-free.

[0139] bath

[0140] Generally, in addition to a metal ion source and at least one inhibitor, the metal electroplating composition of the present invention preferably comprises an electrolyte, i.e., an acidic or basic electrolyte, one or more metal ion sources, optional halide ions, and optional other additives such as surfactants and grain refiners. The bath is usually aqueous. Water can be present in a wide range of amounts. Any type of water can be used, such as distilled water, deionized water, or tap water.

[0141] Preferably, the electroplating bath of the present invention is acidic, i.e., its pH is less than 7. Generally, the pH of a tin or tin alloy electroplating composition is less than 4, preferably less than 3, and most preferably less than 2.

[0142] The electroplating bath of the present invention can be prepared by combining the components in any order. Preferably, the inorganic components such as metal salts, water, electrolyte, and optional halide ion sources are first added to the bath container, followed by the addition of organic components such as surfactants, grain refiners, leveling agents, etc.

[0143] Generally, the electroplating bath of the present invention can be used at any temperature from 10 - 65 °C or higher. Preferably, the temperature of the electroplating bath is 10 - 35 °C, more preferably 15 - 30 °C.

[0144] Suitable electrolytes include, for example but not limited to, sulfuric acid; acetic acid; fluoboric acid; alkylsulfonic acids such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and trifluoromethanesulfonic acid; arylsulfonic acids such as benzenesulfonic acid and toluenesulfonic acid; sulfamic acid; hydrochloric acid; phosphoric acid; tetraalkylammonium hydroxides, preferably tetramethylammonium hydroxide; sodium hydroxide; potassium hydroxide, etc. The acid is usually present in an amount of about 1 - about 300 g / l.

[0145] In one embodiment, the at least one additive comprises a counterion Y selected from methanesulfonate, sulfate, or acetate o- , where o is a positive integer.

[0146] Such electrolytes may optionally contain a source of halide ions, such as chloride ions in tin chloride or hydrochloric acid. A wide range of halide ion concentrations can be used in the present invention, for example, about 0 - about 500 ppm. Generally, the halide ion concentration is about 10 - about 100 ppm, based on the electroplating bath. Preferably, the electrolyte is sulfuric acid or methanesulfonic acid, preferably a mixture of sulfuric acid or methanesulfonic acid and a source of chloride ions. The acids and sources of halide ions that can be used in the present invention are generally commercially available and can be used without further purification.

[0147] Applications

[0148] The electroplating composition of the present invention can be used in various electroplating methods that require a tin-containing layer, and in particular can be used for depositing a tin-containing solder layer on a semiconductor wafer comprising a plurality of conductive bonding structures. The electroplating methods include, but are not limited to, horizontal or vertical wafer electroplating, barrel plating, rack plating, high-speed electroplating (such as roll-to-roll and spray plating), and flashless plating, preferably horizontal or vertical wafer electroplating. A wide range of substrates can be electroplated with the tin-containing deposits of the present invention. The substrate to be electroplated is conductive and can comprise copper, copper alloy, nickel, nickel alloy, nickel-iron-containing materials. Such substrates can be in the form of electronic components, such as (a) lead frames, connectors, chip capacitors, chip resistors, and semiconductor packages, (b) plastics such as circuit boards, and (c) semiconductor wafers. Preferably, the substrate is a semiconductor wafer. Accordingly, the present invention also provides a method of depositing a tin-containing layer on a semiconductor wafer, comprising: providing a semiconductor wafer comprising a plurality of conductive bonding structures; contacting the semiconductor wafer with the composition described above; and applying a sufficient current density to deposit a tin-containing layer on the conductive bonding structures. Preferably, the bonding structure comprises copper, which can be in the form of a pure copper layer, a copper alloy layer, or any interconnect structure comprising copper. Copper pillars are a preferred conductive bonding structure. Optionally, the copper pillars can comprise a top metal layer, such as a nickel layer. When the conductive bonding structure has a top metal layer, a pure tin solder layer is deposited on the top metal layer of the bonding structure. Conductive bonding structures such as bonding pads, copper pillars, etc. are well known in the art, for example as described in US 7,781,325, US2008 / 0054459A, US2008 / 0296761A, and US2006 / 0094226A.

[0149] Method

[0150] Generally, when using the present invention to deposit tin or a tin alloy on a substrate, the electroplating bath is agitated during use. The present invention can use any suitable agitation method and such methods are well known in the art. Suitable agitation methods include, but are not limited to, inert gas or air spraying, workpiece agitation, collision, etc. Such methods are known to those skilled in the art. When using the present invention to electroplate an integrated circuit substrate such as a wafer, the wafer can be rotated, for example, at 1 - 150 RPM and the electroplating solution is contacted with the rotating wafer, for example, by pumping or spraying. In an alternative, the wafer does not need to be rotated if the electroplating bath flow is sufficient to provide the desired metal deposition.

[0151] Depositing tin or a tin alloy in accordance with the present invention into a recess results in substantially no porosity formation in the metal deposit. The term "substantially no porosity formation" means that there are no pores in the metal deposit greater than 1000 nm, preferably 500 nm, and most preferably 100 nm.

[0152] Electroplating equipment for electroplating semiconductor substrates is well-known. The electroplating equipment includes an electroplating bath that contains a tin or tin alloy electrolyte and is made of a suitable material such as plastic or other materials that are inert to the electroplating solution. The bath can be cylindrical, especially for wafer electroplating. The cathode is horizontally disposed in the upper half of the bath and can be any type of substrate, such as a silicon wafer with openings.

[0153] These additives can be used with soluble and insoluble anodes in the presence or absence of one or more membranes that separate the cathode electrolyte from the anode electrolyte.

[0154] The cathode substrate and the anode are electrically connected by wiring and are respectively connected to a power source. The cathode substrate for direct current or pulsed current has a net negative charge so that metal ions in the solution are reduced at the cathode substrate, thereby forming an electroplated metal on the cathode surface. An oxidation reaction occurs at the anode. The cathode and the anode can be horizontally or vertically disposed in the bath.

[0155] Generally, when preparing tin or tin alloy bumps, a photoresist layer is applied to the semiconductor wafer, and then standard photolithography exposure and development techniques are performed to form a patterned photoresist layer (or electroplating mask) with openings or vias therein. The size of the electroplating mask (the thickness of the electroplating mask and the size of the openings in the pattern) defines the size and position of the tin or tin alloy layer deposited on the I / O pads and the UBM. The diameter of such deposits is usually 1 - 300 μm, preferably 2 - 100 μm.

[0156] Unless otherwise specified, all percentages, ppm or similar values are by weight relative to the total weight of each composition. All cited references are incorporated herein by reference.

[0157] The following examples will further illustrate the invention without limiting the scope of the invention.

[0158] Analysis methods

[0159] The molecular weight of the inhibitor was determined by size exclusion chromatography (SEC). Polystyrene was used as the standard sample, and tetrahydrofuran was used as the eluent. The temperature of the column was 30 °C, the injection volume was 30 μL (microliters), and the flow rate was 1.0 ml / minute. The weight-average molecular weight (M w ), number-average molecular weight (M n ), and polydispersity PDI (M w / M n ) of the inhibitor were determined.

[0160] The amine value was determined by titrating a solution of the polymer in acetic acid with perchloric acid according to DIN 53176.

[0161] Coplanarity and topography were determined (roughness) by measuring the height of the substrate with a laser scanning microscope.

[0162] The patterned photoresist contains vias with a diameter of 8 μm and a depth of 15 μm, as well as preformed copper μ-bumps with a height of 5 μm. The isolated (iso) region consists of a 3×6 column array with a center-to-center distance (pitch) of 32 μm. The dense region consists of an 8×16 column array with a center-to-center distance (pitch) of 16 μm. To calculate the die coplanarity, the bumps in 3 isolated regions and the bumps at the centers of 3 dense regions were taken.

[0163] The in-die (WID) coplanarity (COP) was determined using the following formula:

[0164] COP = (H 孤立区 - H 密集区 ) / H Av

[0165] Here, H 孤立区 and H 密集区 are the average heights of the bumps in the isolated / dense regions, and H AV is the overall average height of all the bumps in the isolated and dense regions as described above.

[0166] The average roughness R was calculated using the following formula a

[0167]

[0168] Here, H i is the height at position i on a specific bump. During laser scanning of the surface of a bump, the heights at n positions were measured. H 平均 is the average height of all n positions of a bump. Examples

[0169] Example 1: Preparation of Inhibitor

[0170] Example 1.3

[0171] Diethylenetriamine (346.5 g) was placed in a 3.5 L autoclave. After purging with nitrogen, the pressure was adjusted to 1.5 bar. Then, ethylene oxide (739.8 g) was added over 8 hours at 120 °C, reaching a maximum pressure of 5 bar. To complete the reaction, the mixture was then reacted at 120 °C for 8 hours. Then, the temperature was lowered to 80 °C and volatile compounds were removed under vacuum at 80 °C. A light brown liquid (1085.5 g) with an amine value of 528 mg KOH / g was obtained in the pre-step 1.

[0172] Put pre-step 1 (97 g) and potassium tert-butoxide (15.8 g) into a 3.5 L autoclave. After purging with nitrogen, the pressure was adjusted to 1.5 bar, and the mixture was homogenized at 130 °C for 1 hour. Then, propylene oxide (918.2 g) and ethylene oxide (35.7 g) were added at 130 °C over 6 hours, reaching a maximum pressure of 5 bar. To complete the reaction, the mixture was then reacted at 130 °C and 7 bar pressure for 15 hours. Then, the temperature was lowered to 80 °C and volatile compounds were removed under vacuum at 80 °C. Surfactant 3 was obtained as a pale yellow liquid (998 g) with an amine value of 47.5 mg / g.

[0173] Example 1.4:

[0174] Put diethylenetriamine (245.2 g) into a 3.5 L autoclave. After purging with nitrogen, the pressure was adjusted to 1.5 bar. Then, propylene oxide (689 g) was added at 90 °C over 10 hours, reaching a maximum pressure of 5 bar. To complete the reaction, the mixture was then reacted at 130 °C for 8 hours. Then, the temperature was lowered to 80 °C and volatile compounds were removed under vacuum at 80 °C. Pre-step 2 gave a light brown liquid (901 g) with an amine value of 419.8 mg KOH / g.

[0175] Put pre-step 2 (144.5 g) and potassium tert-butoxide (0.9 g) into a 3.5 L autoclave. After purging with nitrogen, the pressure was adjusted to 1.5 bar, and the mixture was homogenized at 130 °C for 1 hour. Then, propylene oxide (319.9 g) was added at 130 °C over 4 hours, reaching a maximum pressure of 6 bar. The mixture was then reacted for 6 hours. Subsequently, ethylene oxide (105.1 g) was added at 130 °C over 3 hours, reaching a maximum pressure of 4 bar. To complete the reaction, the mixture was then reacted at 130 °C for 6 hours. Then, the temperature was lowered to 80 °C and volatile compounds were removed under vacuum at 80 °C. Surfactant 4 was obtained as an orange liquid (591 g) with an amine value of 105.2 mg / g.

[0176] Example 1.5

[0177] Put diethylenetriamine (619 g) into a 5.0 L autoclave. After purging with nitrogen, the pressure was adjusted to 1.5 bar. Then, ethylene oxide (1320 g) was added at 90 °C over 10 hours, reaching a maximum pressure of 5 bar. To complete the reaction, the mixture was then reacted for 8 hours. Then, the temperature was lowered to 80 °C and volatile compounds were removed under vacuum at 80 °C. Pre-step 3 gave a light brown liquid (1085.5 g) with an amine value of 516.8 mg / g.

[0178] Charge the pre-step 3 (80.9 g) and potassium tert-butoxide (0.94 g) into a 3.5 L autoclave. After purging with nitrogen, adjust the pressure to 1.5 bar, and homogenize the mixture at 130 °C for 1 hour. Then, add propylene oxide (493.7 g) and ethylene oxide (55.1 g) over 12 hours at 130 °C, reaching a maximum pressure of 6 bar. To complete the reaction, allow the mixture to react for an additional 12 hours at 130 °C and 7 bar pressure. Then, lower the temperature to 80 °C and remove volatile compounds under vacuum at 80 °C. Surfactant 5 was obtained as a pale yellow liquid (1219 g) with an amine value of 49.7 mg / g.

[0179] Example 1.6

[0180] Charge diethylenetriamine (346.5 g) into a 3.5 L autoclave. After purging with nitrogen, adjust the pressure to 1.5 bar. Then, add ethylene oxide (739.8 g) over 8 hours at 120 °C, reaching a maximum pressure of 5 bar. To complete the reaction, allow the mixture to react for an additional 8 hours at 120 °C. Then, lower the temperature to 80 °C and remove volatile compounds under vacuum at 80 °C. Pre-step 1 yielded a light brown liquid (1085.5 g) with an amine value of 516.8 mg KOH / g.

[0181] Charge the pre-step 1 (157.4 g) and potassium tert-butoxide (0.93 g) into a 3.5 L autoclave. After purging with nitrogen, adjust the pressure to 1.5 bar, and homogenize the mixture at 130 °C for 1 hour. Then, add propylene oxide (348.5 g) and ethylene oxide (114.5 g) over 12 hours at 130 °C, reaching a maximum pressure of 6 bar. To complete the reaction, allow the mixture to react for an additional 12 hours at 130 °C and 7 bar pressure. Then, lower the temperature to 80 °C and remove volatile compounds under vacuum at 80 °C. Surfactant 6 was obtained as a pale yellow liquid (601 g) with an amine value of 109.3 mg / g.

[0182] Example 1.7

[0183] Charge triaminoethylamine (396 g) into a 3.5 L autoclave. After purging with nitrogen, adjust the pressure to 1.5 bar. Then, add propylene oxide (943.7 g) over 10 hours at 90 °C, reaching a maximum pressure of 6 bar. To complete the reaction, allow the mixture to react for an additional 12 hours. Then, lower the temperature to 80 °C and remove volatile compounds under vacuum at 80 °C. Pre-step 4 yielded a light brown liquid (1336 g) with an amine value of 334.1 mg KOH / g

[0184] Pre-step 4 (237.2 g) and potassium tert-butoxide (1.2 g) were placed in a 3.5 L autoclave. After neutralization with nitrogen, the pressure was adjusted to 1 bar and the mixture was homogenized at 130 °C for 1 hour. Then, propylene oxide (751.9 g) was added over 7 hours at 130 °C, reaching a maximum pressure of 5 bar. Then, ethylene oxide (226 g) was added over 3 hours. To complete the reaction, the mixture was then reacted at 130 °C and 7 bar pressure for 12 hours. Then, the temperature was lowered to 80 °C and volatile compounds were removed in vacuo at 80 °C. Surfactant 7 was obtained as a pale yellow liquid (1221 g) with an amine value of 65 mg / g.

[0185] Example 1.8

[0186] Triaminoethylamine (277.8 g) was placed in a 3.5 L autoclave. After neutralization with nitrogen, the pressure was adjusted to 1.5 bar. Then, ethylene oxide (501.6 g) was added over 10 hours at 90 °C, reaching a maximum pressure of 5 bar. To complete the reaction, the mixture was then reacted for 12 hours. Then, the temperature was lowered to 80 °C and volatile compounds were removed in vacuo at 80 °C. Pre-step 5 gave a light brown liquid (1346 g) with an amine value of 526.2 mg KOH / g.

[0187] Pre-step 5 (143.7 g) and potassium tert-butoxide (1.3 g) were placed in a 3.5 L autoclave. After neutralization with nitrogen, the pressure was adjusted to 1 bar and the mixture was homogenized at 130 °C for 1 hour. Then, propylene oxide (691.2 g) and ethylene oxide (61.7 g) were added over 12 hours at 130 °C, reaching a maximum pressure of 6 bar. To complete the reaction, the mixture was then reacted at 130 °C and 7 bar pressure for 12 hours. Then, the temperature was lowered to 80 °C and volatile compounds were removed in vacuo at 80 °C. Surfactant 8 was obtained as a pale yellow liquid (853 g) with an amine value of 97 mg / g.

[0188] Example 2: Tin plating

[0189] Comparative Example 2.1

[0190] A tin plating bath was prepared containing 40 g / l of tin in the form of methanesulfonate, 165 g / l of methanesulfonic acid, 1 g / l of a commercially available antioxidant, and 1 g / l of BNO 12 (a common prior art surfactant for tin plating, obtained from BASF). BNO 12 is β-naphthol ethoxylated with 12 moles of ethylene oxide per mole of β-naphthol.

[0191] Electroplate 5 μm of tin on nickel-coated copper microbumps. The copper microbumps have a diameter of 8 μm and a height of 5 μm. The nickel layer is 1 μm thick. Immerse a 2 cm × 2 cm large wafer specimen with a 15-μm-thick patterned photoresist layer into the electroplating bath described above, and apply a direct current of 16 ASD at 25 °C for 37 seconds. Detect the electroplated tin bumps with a laser scanning microscope (LSM) and a scanning electron microscope (SEM). The measured average roughness (Ra) is 0.4 μm, and the coplanarity (COP) is 4%.

[0192] From Figure 1 It can be seen that, compared with other figures and by comparing the average roughness (Ra) of 0.4 μm with the Ra of other embodiments, using Lugalvan BNO 12 results in a rough surface of the tin bumps.

[0193] Comparative Example 2.2

[0194] Prepare a tin electroplating bath containing an additional 0.02 g / l of benzylideneacetone (grain refiner) and 10 ml / l of isopropanol as described for Comparative Example 2.1. The electroplating procedure is the same as that described for Comparative Example 2.1. Detect the electroplated tin bumps with a laser scanning microscope (LSM) and a scanning electron microscope (SEM). The measured average roughness (Ra) is 0.12 μm, and the coplanarity (COP) is -11%.

[0195] From Figure 2 It can be seen that, compared with Comparative Example 2.1, the presence of benzylideneacetone in Comparative Example 2.2 results in a decrease in surface roughness but has a negative impact on coplanarity, that is, the electroplated height is more uneven.

[0196] Example 2.3

[0197] Prepare a tin electroplating bath containing 1 g / l of surfactant 3 instead of Lugalvan BNO12 as described for Comparative Example 2.1. The electroplating procedure is the same as that described for Comparative Example 2.1. Detect the electroplated tin bumps with a laser scanning microscope (LSM) and a scanning electron microscope (SEM). The measured average roughness (Ra) is 0.17 μm, and the coplanarity (COP) is 1%.

[0198] The results are summarized in Table 1 and depicted in Figure 3 in.

[0199] Compare the results of Comparative Example 2.1( Figure 1 ) and 2.3( Figure 3 ). Compared with Lugalvan BNO12, when using surfactant 3, tin electroplating produces a much smoother surface.

[0200] In addition, the comparison of the COP results of Examples 2.2 and 2.3 shows that much better coplanarity was achieved in tin electroplating when using Surfactant 3 as compared with the combination of Lugalvan BNO12 and benzylideneacetone as a grain refiner.

[0201] Example 2.4

[0202] A tin electroplating bath containing 1 g / l of Surfactant 4 in place of Lugalvan BNO12 was prepared as described for Comparative Example 2.1. The electroplating procedure was the same as that described for Comparative Example 2.1. The electroplated tin bumps were examined using a laser scanning microscope (LSM) and a scanning electron microscope (SEM). The average roughness (Ra) was measured to be 0.17 μm and the coplanarity (COP) was 3%.

[0203] The results are summarized in Table 1 and depicted in Figure 4 .

[0204] Using Surfactant 4 in the electroplating bath of Example 2.4 produced a smoother surface and a more uniform electroplating height as compared with using Lugalvan BNO12 in Comparative Examples 2.1 and 2.2.

[0205] Example 2.5

[0206] A tin electroplating bath containing 1 g / l of Surfactant 5 in place of Lugalvan BNO12 was prepared as described for Comparative Example 2.1. The electroplating procedure was the same as that described for Comparative Example 2.1. The electroplated tin bumps were examined using a laser scanning microscope (LSM) and a scanning electron microscope (SEM). The average roughness (Ra) was measured to be 0.17 μm and the coplanarity (COP) was 4%.

[0207] The results are summarized in Table 1 and depicted in Figure 5 .

[0208] Using Surfactant 5 in the electroplating bath of Example 2.5 produced a smoother surface and a more uniform electroplating height as compared with using Lugalvan BNO12 in Comparative Examples 2.1 and 2.2.

[0209] Example 2.6

[0210] A tin electroplating bath containing 1 g / l of Surfactant 6 in place of Lugalvan BNO12 was prepared as described for Comparative Example 2.1. The electroplating procedure was the same as that described for Comparative Example 2.1. The electroplated tin bumps were examined using a laser scanning microscope (LSM) and a scanning electron microscope (SEM). The average roughness (Ra) was measured to be 0.16 μm and the coplanarity (COP) was 4%.

[0211] The results are summarized in Table 1 and depicted inFigure 6 in

[0212] Compared with the use of Lugalvan BNO12 in Comparative Examples 2.1 and 2.2, the use of Surfactant 6 in the electroplating bath of Example 2.6 produced a smooth surface and a uniform electroplating height.

[0213] Example 2.7

[0214] Prepare a tin electroplating bath containing 1 g / l of Surfactant 7 instead of Lugalvan BNO12 as described for Comparative Example 2.1. The electroplating procedure was the same as that described for Comparative Example 2.1. The electroplated tin bumps were examined using a laser scanning microscope (LSM) and a scanning electron microscope (SEM). The average roughness (Ra) was measured to be 0.16 μm and the coplanarity (COP) was 3%.

[0215] The results are summarized in Table 1 and depicted in Figure 7 in

[0216] Compared with the use of Lugalvan BNO12 in Comparative Examples 2.1 and 2.2, the use of Surfactant 7 in the electroplating bath of Example 2.7 produced a smooth surface and a uniform electroplating height.

[0217] Example 2.8

[0218] Prepare a tin electroplating bath containing 1 g / l of Surfactant 8 instead of Lugalvan BNO12 as described for Comparative Example 2.1. The electroplating procedure was the same as that described for Comparative Example 2.1. The electroplated tin bumps were examined using a laser scanning microscope (LSM) and a scanning electron microscope (SEM). The average roughness (Ra) was measured to be 0.17 μm and the coplanarity (COP) was 3%.

[0219] The results are summarized in Table 1 and depicted in Figure 8 in

[0220] Compared with the use of Lugalvan BNO12 in Comparative Examples 2.1 and 2.2, the use of Surfactant 8 in the electroplating bath of Example 2.8 produced a smooth surface and a uniform electroplating height.

[0221] Table 1

[0222] Example Inhibitor Grain Refiner Ra [μm] COP [%] Comparative Example 2.1 Lugalvan BNO 12 - 0,4 4 Comparative Example 2.2 Lugalvan BNO 12 Benzylideneacetone 0,12 -11 2.3 Surfactant 3 - 0,17 1 2.4 Surfactant 4 - 0,17 3 2.5 Surfactant 5 - 0,17 4 2.6 Surfactant 6 - 0,16 4 2.7 Surfactant 7 - 0,16 3 2.8 Surfactant 8 - 0,17 3

Claims

1. An aqueous composition comprising stannous ions and at least one compound of formula I: Wherein: X 1 、 X 2 are independently selected from linear or branched C1-C 12 alkanediyl, which may optionally be interrupted by O or S, R 11 is a monovalent group of formula -(O-CH2-CHR 41 ) m -OR 42 ; R 12 、R 13 、R 14 are independently selected from H, R 11 and R 40 ; R 15 selected from H, R 11 , R 40 and -X 4 -N(R 21 )2, X 4 is selected from (a) a linear or branched C1-C 12 alkanediyl and (b) a divalent group of the formula -(O-CH2-CHR 41 ) o - R 21 Selected from R 11 and R 40 , R 40 is a straight-chain or branched C1-C 20 alkyl group, R 41 selected from H and linear or branched C1-C5 alkyl groups, R 42 selected from H and straight-chain or branched C1-C 20 alkyl groups, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl, n is an integer from 1 to 6, m is an integer from 2 to 250, and o is an integer from 1 to 250; Wherein the aqueous composition is free of cupric ions.

2. The aqueous composition according to claim 1, wherein X 1 and X 2 are independently selected from C1-C6 alkanediyls.

3. The aqueous composition according to claim 2, wherein X 1 and X 2 are independently selected from methanediyl, ethanediyl or propanediyl.

4. The aqueous composition according to claim 1, wherein X 1 and X 2 is -(CHR 41 ) q -[Q-(CHR 41 ) r s -, where Q is selected from O, S, and where q + r·s is the number of C atoms in the spacer group.​ 5. The aqueous composition according to claim 4, wherein Q = O and q = r = 1 or 2.

6. The aqueous composition according to any one of claims 1-5, wherein R 41 is selected from H, methyl and ethyl.

7. The aqueous composition according to claim 6, wherein R 41 is selected from H and methyl.

8. The aqueous composition according to any one of claims 1-5, wherein R 12 , R 13 and R 14 are selected from R 11 .

9. The aqueous composition according to claim 6, wherein R 12 , R 13 and R 14 are selected from R 11 .

10. The aqueous composition according to any one of claims 1-5, wherein R 15 is selected from R 11 and -X 4 -N(R 21 )2.

11. The aqueous composition according to claim 9, wherein R 15 is selected from R 11 and -X 4 -N(R 21 )2.

12. The aqueous composition according to any one of claims 1-5, wherein R 11 is a copolymer of ethylene oxide and other C3-C4 alkylene oxides.

13. The aqueous composition according to claim 11, wherein R 11 is a copolymer of ethylene oxide and other C3-C4 alkylene oxides.

14. The aqueous composition according to claim 12, wherein in the copolymer of ethylene oxide and other C3-C4 alkylene oxides, the content of ethylene oxide is 5-50% by weight.

15. The aqueous composition according to claim 13, wherein in the copolymer of ethylene oxide and other C3-C4 alkylene oxides, the content of ethylene oxide is 5-50% by weight.

16. The aqueous composition according to claim 14, wherein in the copolymer of ethylene oxide and other C3-C4 alkylene oxides, the content of ethylene oxide is 5-40% by weight.

17. The aqueous composition according to claim 12, wherein in the copolymer of ethylene oxide and other C3-C4 alkylene oxides, the content of ethylene oxide is 5-30% by weight.

18. The aqueous composition according to claim 13, wherein in the copolymer of ethylene oxide and other C3-C4 alkylene oxides, the content of ethylene oxide is 5-30% by weight.

19. The aqueous composition according to claim 17, wherein in the copolymer of ethylene oxide and other C3-C4 alkylene oxides, the content of ethylene oxide is 8-20% by weight.

20. The aqueous composition according to any one of claims 1-5, comprising a single grain refiner of a non-α,β-unsaturated aliphatic carbonyl compound.

21. The aqueous composition according to claim 18, comprising a single grain refiner of a non-α,β-unsaturated aliphatic carbonyl compound.

22. The aqueous composition according to any one of claims 1-5, substantially free of grain refiners.

23. The aqueous composition according to claim 18, substantially free of grain refiners.

24. Use of the aqueous composition according to any one of claims 1-23 for depositing tin or a tin alloy on a substrate, the substrate comprising a structure with a pore size of 500 nm to 500 μm.

25. A method for electrodepositing tin or a tin alloy on a substrate, comprising: a) contacting a composition comprising stannous ions and at least one compound of formula I with the substrate, Wherein: X 1 and X 2 are independently selected from linear or branched C1-C 12 alkanediyl, which may optionally be interrupted by O or S, R 11 is a monovalent group of the formula -(O-CH2-CHR 41 ) m -OR 42 and R 12 、R 13 、R 14 are independently selected from H, R 11 and R 40 ; R 15 Selected from H, R 11 , R 40 and -X 4 -N(R 21 )2, X 4 is selected from (a) a linear or branched C1-C 12 alkanediyl and (b) a divalent group of the formula -(O-CH2-CHR 41 ) o - R 21 selected from R 11 and R 40 , R 40 is a straight-chain or branched C1-C 20 alkyl group, R 41 selected from H and linear or branched C1-C5 alkyl groups, R 42 selected from H and linear or branched C1-C 20 alkyl groups, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl, n is an integer from 1 to 6, m is an integer from 2 to 250, and o is an integer from 1 to 250, Wherein the composition is free of cupric ions; and b) applying a current to the substrate for a time sufficient to deposit a layer of tin or a tin alloy on the substrate, Wherein the substrate comprises a structure with a pore size of 500 nm to 500 μm and the deposition is carried out to fill these structures.

26. The method according to claim 25, wherein the pore size is 1-200 μm.

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