Composition for metal electroplating comprising an additive for defect-free filling of features on electronic substrates

Abstract

The present invention provides a non-acidic aqueous composition for copper electroplating comprising (a) copper ions; (b) at least one additive of formula S1.

Description

[0001] Composition for metal electroplating comprising an additive for defect-free filling of features on electronic substrates

[0002] The invention relates to a composition for metal electroplating for bottom-up filling of features on electronic substrates, in particular those having micrometer dimensions and / or high aspect ratios, particularly filling of though silicon vias.

[0003] Background of the Invention

[0004] Filling of features, such as vias and trenches, by copper electroplating is an essential part of the semiconductor manufacture process. It is well known that the presence of organic substances as additives in the electroplating bath can be crucial in achieving a uniform metal deposit on a substrate surface and in avoiding defects, such as voids and seams, within the vias.

[0005] One class of additives are the so-called suppressors, suppressing agents or sometimes simply surfactants. Suppressors are used to provide a substantially bottom-up filling of small features like vias or trenches. The smaller the features are and the higher the aspect ratio of the feature is the more sophisticated the additives have to be to avoid voids and seams. In literature, a variety of different suppressing compounds have been described. The mostly used class of suppressors are polyether compounds like polyglycols or polyalkylene oxides like ethylene oxide propylene oxide copolymers.

[0006] WO 2006 / 053242 A1 discloses amine-based polyoxyalkylene suppressors comprising oxyethylene and oxypropylene groups. The amine may be methylamine, ethylamine, propylamine, ethylendiamine, diethylenetriamine, diaminopropane, diethyleneglykol diamine or triethylenglycol diamine. The copolymers may have block, alternating or random structure.

[0007] WO 2010 / 115717, WO 2011 / 012475, and WO 2018 / 114985 disclose compositions comprising suppressors based on particular amine started polyalkoxyalkylene copolymers comprising oxyethylene and oxyproyplene groups for copper electrodeposition on copper seeds.

[0008] WO 2017 / 42334 A1 discloses a plating bath that comprises copper ions, an acid and an additive obtainable by a reaction of at least one aminoglycidyl compound comprising at least one amino group which bears at least one glycidyl moiety and a second compound selected from ammonia and amine compounds wherein the amine compounds comprise at least one primary or secondary amino group. The aminoglycidyl compound and / or the amine compound contains at least one polyoxyalkylene residue, such as ethylene oxide, propylene oxide and / or butylene oxide. The polyoxyalkylene residues may comprise further alkylene oxides or styrene oxide, typically only in small amounts such as 0.1 to 5 mol-% based on the entire polymer. 240161W001

[0009] 2

[0010] With shrinking aperture size and increasing aspect ratio filling of such features, particularly through silicon vias (TSV) with copper via electroplating without causing voids or seams in the deposit.

[0011] It is therefore an object of the present invention to provide a copper electroplating composition that is capable of providing a substantially voidless and seamless filling of features on the micrometer scale comprising a metal seed with a copper electroplating bath, particularly an acidic copper electroplating composition for filling through silicon vias.

[0012] It is a further object of the present invention to provide a copper electroplating composition that provides bottom-up fill capability, particularly into features having an aperture size of from 500 nm to 50 pm and an aspect ratio of 4 or more.

[0013] Summary of the Invention

[0014] Surprisingly, it has now been found, that polyoxyalkylated amine compounds that have a specific content of aryl substituted oxyalkyl show a good or even better bottom-up filling capability to ensure void- and seamless filling as well as a good or even better plating speed.

[0015] Therefore, the present invention provides an acidic aqueous composition for copper electroplating comprising

[0016] (a) copper ions;

[0017] (b) at least one additive of formula S1 wherein

[0018] Xs1is selected from a linear, branched or cyclic C1-C12 alkanediyl, which may be substituted or unsubstituted, and which may optionally be interrupted by 0, S or NRS40;

[0019] RS1is selected from (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)mH, -Xs4-N[-(C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)m]2, Zs, Xs5- Zs, XS4-N(ZS)2;

[0020] Rs2is selected from H, Rs1, or Rs40;;

[0021] Rs3is selected from H, Rs1, Rs4°; or Rs3and an adjacent group Rs4together form a divalent group Xs2;

[0022] Rs4is selected from H, Rs1, Rs4°; or, if n>3, may also be As1; or, if n>2, two adjacent groups Rs4may also together form a divalent group Xs2;

[0023] Rs5is (a) a Ce to C15 carbocyclic aromatic group or a C5 to C14 heterocyclic aromatic group in which one or two carbon atoms are substituted by N atoms, and which carbocyclic or heterocyclic aromatic group or is unsubstituted or substituted by one or more alkyl or alkoxy or (b) a Ci to Ce alkyl that is substituted by a group (a) as defined above; 240161W001

[0024] Rs6is methyl or ethyl;

[0025] Rs4° is a linear or branched C1-C20 alkyl, which may optionally be substituted by hydroxy, alkoxy, or alkoxycarbonyl;

[0026] Asi is a continuation

[0027] Xs2is selected from a linear or branched C1-C12 alkanediyl, which may be substituted or unsubstituted, and which may optionally be interrupted by 0, S or NRS40; and

[0028] Xs3is a linear or branched Ci to C12 alkanediyl, which may be interrupted by 0 and S atoms or substituted by 0- Rs31;

[0029] Xs4is a linear or branched Ci to C12 alkanediyl;

[0030] Xs5is a divalent group comprising at least one C2 to Ce polyoxyalkylene;

[0031] Rs31, Rs32are independently selected from (a) (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)mor (b) a further branching group to form a multiple branching group (ZsP)p(Rs31aRs32a)2P, wherein Rs31aand Rs32aare independently selected from (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)m;

[0032] ZSP is selected from is an integer of from 1 to 100; is an integer of from 0 to 10; is an integer of from 1 to 600; is an integer from 1 to 200, where s is counted for n; 240161W001

[0033] 4 p is an integer of from 2 to 4; wherein the ratio m / ((o+k+m) is 3 to 30 %. and wherein the content of k / ((o+k+m) is 10% or below.

[0034] In contrast to WO 2017 / 42334 A1, that (only) contains low amounts of polyoxyalkylene groups in a polymer backbone prepared by polymerizing an aminoglycidyl and an amine compound that comprise such polyoxyalkylene groups, the subject invention comprises polyoxyalkylene groups comprising a specific aromatic content in the side chains attached to an amine starter as defined above.

[0035] The invention further relates to the use of a copper electroplating bath comprising a composition as described herein for depositing copper on substrates comprising a recessed feature having an aperture size from 500 nm to 50 m, which feature comprises a metal seed layer, particularly a copper or cobalt seed layer, particularly through silicon vias.

[0036] The invention further relates to a process for depositing copper a comprising the steps

[0037] (a) providing a substrate comprising a recessed feature having an aperture size from 500 nm to 50 and an aspect ratio from at least 4, which feature comprises a metal seed layer;

[0038] (b) contacting the composition as described herein with the substrate, and

[0039] (c) applying a current to the substrate for a time sufficient to deposit a metal layer onto the metal seed layer and to fill the nanometer sized feature.

[0040] Brief description of the Figures

[0041] Fig. 1 shows a SEM image of partially filled via after copper electroplating according to example B1;

[0042] Fig. 2 shows a SEM image of partially filled via after copper electroplating according to example B2;

[0043] Fig. 3 shows a SEM image of partially filled via after copper electroplating according to example B3;

[0044] Fig. 4 shows a SEM image of partially filled via after copper electroplating according to example B4;

[0045] Fig. 5 shows a SEM image of partially filled via after copper electroplating according to example B5.

[0046] Detailed Description of the Invention

[0047] Definitions

[0048] As used herein, "acidic” means that the pH of the plating bath is below 7, preferably below 5. More preferably the pH of the acidic plating bath is below 4, even more preferably below 3, most preferably below 2.

[0049] As used herein, “arylalkylene” means an alkylene that is substituted by a carbocyclic or N-heterocyclic aromatic group. 240161W001

[0050] 5

[0051] As used herein, "aryloxyalkylene” means a divalent groups that is derived from an oxiran or alkylene epoxide which is substituted by a carbocyclic or N-heterocyclic aromatic group as specified herein.

[0052] As used herein, "alkoxy lating” or "alkoxy lation” generally means a polyaddition of substituted or unsubstituted alkylene oxides to an amine starter.

[0053] As used herein, "block” means that the comonomers are polymerized after each other to form blocks of the respective co-monomers in any predefined order. "Block poly(oxyethylene-co-aryloxyalkylene)” means that the amino group is first substituted by a polyoxyethylene group (EO) followed by a poly (ary loxy alky lene) group (ArO), further also referred to as -(EO)o-(ArO)m. In contrast, a "block poly(aryloxyalkylene-co-oxyethylene)” means that the amino group is first substituted by a polyaryloxyalkylene group (ArO) followed by a polyoxyethylene group (EO), further also referred to as -(ArO)m-(EO)o. By way of nonlimiting example, for EO and the arylalkylene oxide (ArO) comonomers such blocks may be, but are not limited to: -EOo-ArOm, -ArOm-EOo, -EOoi-ArOm-EOo2, -ArOmi-EOo-ArOm2, etc., wherein m1 +m2=m and o1 +o2=o. The leading bond here indicates the bonding to the amine starter.

[0054] A "random poly(oxyethylene-co-polyaryloxyalkylene)” is a copolymer that is prepared from a mixture of ethylene oxide and the arylalkylene oxide, further also referred to as -EOo / ArOm. The aromatic content refers to the content of the aryloxyalkylene in relation to the sum of oxyethylene and the aryloxyalkylene (and other C3-C4-oxyalkylene) in the RS1side chains.

[0055] All percent, ppm or comparable values refer to the weight with respect to the total weight of the respective composition except where otherwise indicated. All cited documents are incorporated herein by reference.

[0056] Additives according to the invention

[0057] Due to its suppressing capabilities the additive is also referred to herein as "suppressing agent” or "suppressor”.

[0058] Besides the acidic electrolyte the aqueous composition according to the present invention comprises at least one additive of formula S1

[0059] Generally, the suppressing agent consists of an amine starter comprising one or more side chains comprising ethylene oxide and arylalkylene oxide in a specific amount.

[0060] In formula S1 , Xs1is a spacer group within the amine starter. It may be a linear, branched or cyclic C1-C12 alkanediyl, which may be substituted or unsubstituted, preferably unsubstituted. Such alkanediyl spacer may optionally be interrupted by 0, S or NRS40. 240161 W001

[0061] 6

[0062] In a first preferred embodiment Xs1is Ci-Ce alkanediyl, more preferably C1-C4 alkanediyl, most preferably methanediyl, 1 ,2-ethanediyl or 1 ,3-propanediyl. In a second preferred embodiment heteroatoms are present and Xs1may be -(CH2)q-[Q-(CH2)r]s-, wherein Q is selected from 0, S and NRS40, q and r are integers from 1 to 6, s is an integer from 1 to 4 and q + (r x s) is the total number of C atoms in Xs1. Particularly preferred is an etheramine spacer with Q=0 and q=r = 1 or 2, and s=1. Useful substituents may be hydroxy, alkoxy, and alkoxycarbonyl. Preferably the spacer group Xs1does not comprise any hydroxy substituents. Most preferably Xs1is unsubstituted.

[0063] Generally, n may be an integer of from 1 to 600. In a first embodiment, the starter is a low molecular weight polyamine in which n is an integer from 1 to 5, preferably from 1 to 3; most preferably the starter is selected from ethylene diamine, diethylene triamine, or triethylene tetramine. Alternative low molecular weight starters are etheramines. In a second embodiment, the starter is a polyethylene imine wherein n is from 6 to 600, preferably 20 to 300; most preferably the starter is a polyethyleneimine having a number-average molecular mass of from 500 to 2000 g / mol.

[0064] RS1is a copolymer side chain that comprises 0 oxyethylene groups (also referred to as “EO”), k oxy-Ca to C4 alkylene groups (also referred to as "higher alkylene oxide” or “AkO”), and m oxy-arylalkylene groups (also referred to as “ArO”).

[0065] Rs2may be selected from H, Rs1, or Rs40, preferably H or Rs1, most preferably Rs1.

[0066] Rs3may be selected from H, Rs1, Rs4°. Alternatively, Rs3and an adjacent group Rs4may together form a divalent group Xs2to form cyclic amine starters. Preferably Rs3is RS1as defined above.

[0067] Rs4may be selected from H, Rs1, or Rs4°. For n>3, particularly if polymeric amine starters (polyethylene imines) with n > 10 or even > 20 are used, Rs4may also be a continuation of the backbone AS1 with s being an integer from 1 to 300. In this case s is counted for n, i.e. if a continuation (also referred to as a side chain by branching) AS1is present, n is the sum of s and the rest of the groups attributed to n.

[0068] For n>2, two adjacent groups Rs4may also together form a divalent group Xs2to form cyclic amine starters. Preferably Rs4is RS1as defined above.

[0069] The number of oxyethylene (EO) groups 0 may be from 1 to 100, preferably from 1 to 50, more preferably from 1 to 25, most preferably from 5 to 15. The number of aryloxyalkylene (ArO) groups m may be from 1 to 20, preferably from 1 to 18, more preferably from 2 to 15, most preferably from 3 to 10.

[0070] The ratio m / (o+k+m) in the side chain(s) of the suppressing agent (excluding the starter), also referred to as "aromatic content”, may be from 3 to 30 %, preferably from 4 to 28 %, more preferably from 5 to 27 %, even more preferably from 6 to 26 %, most preferably from 8 to 25 %. If the aromatic content is too low, the void and / or seamless filling capability of the suppressor is insufficient. If the aromantic content is too high, the suppressors tend to be at least partly insoluble in the aqueous electroplating composition.

[0071] It needs to be emphasized that macroscopically the oxyethylene-co-aryloxyalkylene polymers are no discrete molecules but have a statistical distribution of different single polymers. Therefore, all numbers m, o, and k as well as the numbers derived from these, are to be treated as average numbers of the respective copolymers. The same is true, if the starter itself is a polymer like PEI.

[0072] The oxy-C3-C4-alkylene (PO or BuO) groups are optional and the number of k may generally be from 0 to 10, preferably from 0 to 5, more preferably from 0 to 2, most preferably 0.

[0073] The higher alkylene oxide content k / ((o+k+m) should be 10 % or below, preferably 5 % or below, more preferably 2 % or below. Most preferably no higher alkylene oxide is present in the suppressor. If the amount of higher alkylene oxide is too high, the suppressors tend to be insoluble in the aqueous electroplating composition, particularly when the aromatic content is high.

[0074] RS1may have block, random, alternating or gradient structure. Preferably RS1is a block poly(oxyethylene-co- aryloxyalkylene), a poly(aryloxyalkylene-co-oxyethylene) or a random poly(oxyethylene-co-aryloxyalkylene).

[0075] Rs5may be a Ce to C15 carbocyclic aromatic group or a C5 to C14 heterocyclic aromatic group in which one or two carbon atoms are substituted by N atoms, and which carbocyclic or heterocyclic aromatic group or is unsubstituted or substituted by one or more alkyl or alkoxy. Alternatively, Rs5may be a Ci to Ce alkyl that is substituted by a Ce to C15 carbocyclic aromatic group or a C5 to C14 heterocyclic aromatic group in which one or two carbon atoms are substituted by N atoms, and which carbocyclic or heterocyclic aromatic group or is unsubstituted or substituted by one or more alkyl or alkoxy.

[0076] For the avoidance of doubt, the one or two N atoms are counted towards the C atoms of the heteroaromatic group, i.e. a C5 heteroaromatic group with one N atom would contain 4 C atoms and 1 N atom. The same is the case for the substituents, which are also counted towards the C atoms of the of the respective group.

[0077] Preferred Ce to C15 carbocyclic aromatic groups are selected from phenyl; a 2-, 3-, or 4-alkylphenyl, particularly 2- or 4-toluyl; an alkoxyphenyl, particularly methoxyphenyl or ethoxyphenyl, a dialkylphenyl, particularly xylyl, or naphthyl. 240161 WC01

[0078] Preferred Ci to Ce alkyl that is substituted by a Ce to C15 carbocyclic aromatic group are selected from phenylalkyl, particularly benzyl or 2-phenyl-eth-1-yl; a 2-, 3-, or 4-alkylbenzyl particularly 2- or 4-toluylmethyl, a 2-, 3-, or 4- alkoxybenzyl, particularly, methoxybenzyl or ethoxybenzyl; a dialkylbenzyl, particularly xylylmethyl; or a naphtylalkyl, particularly naphtylmethyl or 2-napthyl-eth-1-yl.

[0079] Particularly preferred aryloxyalkylenes are oxystyrene (received from styrene oxide, phenyloxypropylene (received from 2,3-epoxypropylbenzene) or naphtyloxypropylene.

[0080] Rs5may also be a Ce to C15 N-heteroccyclic aromatic group selected from 2-, 3-, or 4-pyridinyl, pyrrolyl, indolyl, or 1- imidazolyl.

[0081] If present, Rs6may be methyl or ethyl, preferably methyl.

[0082] In a first embodiment, group RS1is an ethylene oxide co-polymerized with an arylalkylene oxide to form a poly(oxyethylene)-co-(aryloxyalkylene) copolymer, also referred to as EO / ArO. Optionally lower amounts of a further C3 to C4 alkylene oxide may be co-polymerized. Such further C3 to C4 alkylene oxide may be propylene oxide (also referred to herein as "PC”) or butylene oxide (also referred to herein as “BuO”).

[0083] In a second embodiment RS1is a nitrogen-containing branching group -Xs4-N[-(C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)m]2.

[0084] In a third embodiment group RS1comprises a branching group Zs, Xs5-Zs, or XS4-N(ZS)2, wherein Zsis a group of formula S3:

[0085] In formula S3, Xs3is a linear or branched Ci to C12 alkanediyl, which may be interrupted by 0 and S atoms or substituted by O-Rs31, Preferably Xs3is a Ci to Ce alkanediyl, more preferably methanediyl, ethanediyl, propanediyl or butanediyl, most preferably methanediyl or ethanediyl. Xs4is a linear or branched Ci to C12 alkanediyl. Preferably Xs3is a Ci to Ce alkanediyl, more preferably methanediyl, ethanediyl, propanediyl or butanediyl, most preferably methanediyl or ethanediyl. Rs31and Rs32are independently selected from either (a) (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5- O)mH or (b) a further branching group to form a multiple branching group (ZsP)p(Rs31aRs32a)2P. Like lit. (a), Rs31aand Rs32aare independently selected from (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)m. In formula S3, ZSP is selected from

[0086] Preferably Rs31and Rs32are both poly(oxyethylene)-co-(aryloxyalkylene) copolymer groups (C2H4-O)o(C2H3Rs6-

[0087] O)k(C2H3Rs5-O)mH. p may be an integer from 2 to 4, preferably 2.

[0088] The compounds of formula S1 with RS1= Zsmay be prepared in two steps. First, a multi amine is reacted with a compound that introduces a branching group (further also referred to a "branching agent”), such as but not limited to an epoxide or a carbonate ester of formula

[0089] In a second step the reaction product is reacted with ethylene oxide and the arylalkylene oxide to form the respective suppressing agents according to the invention.

[0090] If RS1is Xs5-Zs, a three-step process is required. In a first step the amine starter is reacted with a first portion of the C2to Ce alkylene oxide, preferably ethylene oxide, followed by reaction with the compound that introduces a branching group and afterwards again with a second portion of ethylene oxide and the arylalkylene oxide as described above.

[0091] In formula S1 , Rs2, Rs3, Rs4are either selected from H, Rs1, Rs4°; or Rs3and an adjacent group Rs4or, if n>2, two adjacent groups Rs4may together form a divalent group Xs2. In the latter case Xs2may be selected from a linear or branched Ci-Ci2alkanediyl, which may optionally be interrupted by 0, S or NRS4°. Rs4° may be (a) linear or branched Ci-C2o alkyl, which may optionally be substituted by hydroxyl, alkoxy or alkoxycarbonyl, and (b) linear or branched Ci-C2o alkenyl, which may optionally be substituted by hydroxyl, alkoxy or alkoxycarbonyl. Preferably Rs4° is a Ci to 240161 WC01

[0092] 10

[0093] Ce alkyl or a Ci to C12 hydroxyalkyl. Preferably Xs2is selected from a linear or branched Ci-Ce alkanediyl, more preferably from a C1-C4 alkanediyl, most preferably from methyl or ethyl or propyl. In this case Xs1is preferably selected so as to form a 5 or 6 membered ring system.

[0094] In a preferred embodiment, all groups Rs2, Rs3, Rs4are a (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)mH group RS1as defined above, preferably (C2H4-O)o(C2H3Rs5-O)mH.

[0095] A first preferred embodiment is an additive of formula (S2a) wherein

[0096] RS1has the prescribed meanings;

[0097] Rs2, Rs3and Rs4are selected from RS1or Rs4°, preferably Rs1; r is an integer from 1 to 8, preferably 2 to 6, most preferably 2, 3 or 4;

[0098] Rs4° has the prescribed meanings and is preferably Ci to Ce alkyl or Ci to C12 hydroxyalkyl; and n is 1 , 2, or 3, preferably 1 or 2, most preferably 1.

[0099] A second preferred embodiment is an additive of formula (S2b)

[0100] RS1has the prescribed meanings;

[0101] Rs2is selected from RS1or Rs4°, preferably Rs1;

[0102] Rs4° has the prescribed meanings and is preferably Ci to Ce alkyl or Ci to C12 hydroxyalkyl; and

[0103] Xs1, Xs2are independently a Ci to C3 alkanediyl, preferably Xs1and Xs2are both ethanediyl or either Xs1or Xs2is methanediyl and the other of Xs1and Xs2is propanediyl.

[0104] Such compounds may be prepared by starting from cyclic amines, such as but not limited to piperazin, methylpiperazin, ethylpiperazin, propylpiperazin, butylpiperazin, and the like.

[0105] A third preferred embodiment is an additive of formula (S2c) wherein

[0106] RS1 has the prescribed meanings; 240161 W001

[0107] 11

[0108] Rs2and Rs3are selected from RS1or Rs4°, preferably Rs1;

[0109] Rs4° has the prescribed meanings and is preferably Ci to Ce alkyl or Ci to C12 hydroxyalkyl; and

[0110] Xs1, Xs11, Xs3are independently a Ci to C3 alkanediyl, preferably Xs1and Xs2are both ethanediyl or either Xs1or Xs2is methanediyl and the other of Xs1and Xs2is propanediyl.

[0111] A fourth preferred embodiment is an additive of formula (S2d) wherein

[0112] RS1 has the prescribed meanings;

[0113] RS2, Rs3and Rs4are selected from RS1or Rs4°, preferably Rs1;

[0114] Rs4° has the prescribed meanings and is preferably Ci to Ce alkyl or Ci to C12 hydroxyalkyl; and

[0115] Xs1, Xs11, Xs3are independently a Ci to C3 alkanediyl, preferably Xs1and Xs2are both ethanediyl or either Xs1or Xs2is methanediyl and the other of Xs1and Xs2is propanediyl.

[0116] Such compounds of embodiments three and four may be prepared by starting from aminoalkylated cyclic amines, such as but not limited to bisaminoethyl piperazine, bisaminopropyl piperazine, bisaminobutyl piperazine, and the like.

[0117] A fifth embodiment is an additive of formula S1 wherein

[0118] RS1is selected from -(C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)mH,

[0119] Rs2, Rs3and Rs4are Rs1;

[0120] Xs1is a Ci to C3 alkanediyl; and m is an integer of from 6 to 25.

[0121] Further useful polyamine starters are described in WO 2018 / 073011 , which are explicitly incorporated herein by reference for this purpose.

[0122] In a sixth embodiment polyethylene amine starters are used to prepare the suppressor by alkoxylating polyethylene imines with ethylene oxide and arylalkylene oxides. Such polyethylene amines

[0123] Generally, the number average molecular mass Mnof the suppressing agent may be from about 300 to about 100 000 g / mol.

[0124] In one embodiment, where low molecular weight amine starters are used, the molecular mass Mnof the suppressing agent may be from about 500 to about 6000 g / mol, preferably from about 1 000 to about 5 000 g / mol, even more preferably from about 1 200 to about 4 000 g / mol, most preferably from about 1 400 to about 3 000 g / mol. A low molecular weight increases the solubility of the suppressing agent in the composition. 240161W001

[0125] 12

[0126] In another embodiment, where polymer amine starters like PEIs are used, the molecular mass Mnof the suppressing agent may be from about 10 000 to about 80 000 g / mol, preferably from about 12 000 to about 70 000 g / mol, even more preferably from about 15000 to about 60 000 g / mol, most preferably from about 20 000 to about 50 000 g / mol.

[0127] The suppressing agents of the invention are typically used in an amount of about 0.1 ppm to about 1000 ppm. Particularly suitable amounts of suppressor useful in the present invention are 1 to 700 ppm, and more particularly 5 to 500 ppm.

[0128] Plating Bath

[0129] A wide variety of metal plating baths may be used with the present invention. Metal electroplating baths typically contain a copper ion source, halide ions, an electrolyte, the suppressing agent, and optionally further additives such as but not limited to accelerators, levelers, surfactants.

[0130] The plating baths are typically aqueous. The term "aqueous” means that the plating bath is water based. The water may be present in a wide range of amounts. Any type of water may be used, such as distilled, deionized or tap. Preferably the plating bath is a solution of the compounds described herein in water. Preferably the water is electronic grade deionized water. Other solvents besides water may be present in minor amounts but preferably water is the only solvent.

[0131] The metal ion source may be any compound capable of releasing copper ions to be deposited in the electroplating bath in sufficient amount, i.e. is at least partially soluble in the electroplating bath. In a preferred embodiment, no further electrodepositable metals besides copper are present in the electroplating bath.

[0132] It is preferred that the copper ion source is soluble in the plating bath to release 100 % of the metal ions. Suitable copper ion sources are metal salts and include, but are not limited to, metal sulfates, metal halides, metal acetates, metal nitrates, metal fluoroborates, metal alkylsulfonates, metal arylsulfonates, metal sulfamates, metal gluconates and the like. It is preferred that the metal is copper. It is further preferred that the source of copper ions is copper sulfate, copper chloride, copper acetate, copper citrate, copper nitrate, copper fluoroborate, copper methane sulfonate, copper phenyl sulfonate and copper p-toluene sulfonate. Copper sulfate pentahydrate and copper methane sulfonate are particularly preferred. Such metal salts are generally commercially available and may be used without further purification.

[0133] The copper ion source may be used in the present invention in any amount that provides sufficient metal ions for electroplating on a substrate. 240161W001

[0134] 13

[0135] Copper is typically present in an amount in the range of from about 0.2 to about 300 g / l of the plating solution. Generally, the suppressor is useful in low copper, medium copper and high copper baths. Typical copper concentrations are from about 10 to about 120 g / l.

[0136] In general, besides the copper ions, halide ions, particularly chloride and / or bromide ions, most particularly chloride, and at least one of the suppressing agents according to the present invention the present copper electroplating compositions preferably include an electrolyte, one or more sources of metal ions and optionally other additives like accelerators and / or levelers. The halides are applied in form of hydrochloric acid or metal chloride, preferably copper chloride.

[0137] A wide range of chloride ion concentrations may be used in the present invention such as from about 0 to about 500 ppm. Typically, the chloride ion concentration is in the range of from about 1 to about 100 ppm, preferably from about 10 ppm to about 100 ppm, most preferably from 20 to 80 ppm, based on the plating bath. It is preferred that the electrolyte is sulfuric acid or methanesulfonic acid, and preferably a mixture of sulfuric acid or methanesulfonic acid and a source of chloride ions. The acids and sources of halide ions useful in the present invention are generally commercially available and may be used without further purification.

[0138] The electroplating baths of the present invention may be prepared by combining the components in any order. It is preferred that the inorganic components such as metal salts, water, electrolyte and optional halide ion source, are first added to the bath vessel followed by the organic components such as leveling agents, accelerators, suppressors, surfactants and the like.

[0139] Typically, the plating baths of the present invention may be used at any temperature from 10 to 65 °C or higher. It is preferred that the temperature of the plating baths is from 10 to 35 °C and more preferably from 15 to 30 °C.

[0140] Suitable acidic electrolytes include such as, but not limited to, sulfuric acid, acetic acid, fluoroboric acid, alkylsulfonic acids such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid and trifluoromethane sulfonic acid, arylsulfonic acids such as phenyl sulfonic acid and toluenesulfonic acid, sulfamic acid, hydrochloric acid, phosphoric acid, and the like. In a particular embodiment the electrolyte does not comprise pyrophosphoric acid. The acids are typically present in an amount in the range of from about 0.1 to about 300 g / l. The plating bath may be a high, a medium or a low acid bath. Typical baths usually comprise one or more acids in a concentration from 20 g / l to 120 g / l.

[0141] Other additives

[0142] The electroplating baths according to the present invention may include one or more optional additives. Such optional additives include, but are not limited to, accelerators, other suppressors, levelers, surfactants and the like. 240161W001

[0143] 14

[0144] Any accelerators may be advantageously used in the plating baths according to the present invention. Accelerators useful in the present invention include, but are not limited to, compounds comprising one or more sulfidic sulfur atoms (such as but not limited to sulfide, disulfide or thiol groups) and one or more sulfonic orphosphonic acid group, combinations thereof, or their salts. Preferably the composition comprises at least one accelerating agent.

[0145] Preferred accelerators have the general structure MAO3XA-RA1-(S)a-RA2, with:

[0146] - MAis a hydrogen or an alkali metal (preferably Na or K)

[0147] - XAis P or S, preferably S

[0148] - a = 1 to 6, preferably 1 or 2

[0149] - RA1is selected from Ci-Cs alkyl group or heteroalkyl group, an aryl group or a heteroaromatic group. Heteroalkyl groups will have one or more heteroatom (N, S, 0) and 1-12 carbons. Carbocyclic aryl groups are typical aryl groups, such as phenyl, naphtyl. Heteroaromatic groups are also suitable aryl groups and contain one or more N,0 or S atom and 1-3 separate or fused rings.

[0150] - RA2is selected from H or (-S-RA1'XA03MA), with RA1' being identical or different from RA1.

[0151] More specifically, useful accelerators include those of the following formulae:

[0152] MA03S-RA1-SH

[0153] MAO3S-RA1-S-S-RA1’-SO3MA

[0154] MAO3S-Ar-S-S-Ar-SO3MAwith RA1is as defined above and Ar is Aryl.

[0155] Particularly preferred accelerating agents are:

[0156] SPS: bis-(3-sulfopropyl)-disulfide disodium salt

[0157] MPS: 3-mercapto-1-propansulfonic acid, sodium salt

[0158] Other examples of accelerators, used alone or in mixture, include, but are not limited to: MES (2- Mercaptoethanesulfonic acid, sodium salt); DPS (N,N-dimethyldithiocarbamic acid (3-sulfopropylester), sodium salt); UPS (3-[(amino-iminomethyl)-thio]-1 -propylsulfonic acid); ZPS (3-(2-benzthiazolylthio)-1 -propanesulfonic acid, sodium salt); 3-mercapto-propylsulfonicacid-(3-sulfopropyl)ester; methyl-(ra-sulphopropyl)-disulfide, disodium salt; methyl-(oo-sulphopropyl)-trisulfide, disodium salt.

[0159] Such accelerators are typically used in an amount of about 0.1 ppm to about 3000 ppm, based on the total weight of the plating bath. Particularly suitable amounts of accelerator useful in the present invention are 1 to 500 ppm, and more particularly 2 to 100 ppm.

[0160] Any additional suppressor may be advantageously used in the present invention. Additional suppressors useful in the present invention include, but are not limited to, polymeric materials, particularly those having heteroatom 240161W001

[0161] 15 substitution, and more particularly oxygen substitution. It is preferred that the suppressor is a polyalkyleneoxide. Suitable additional suppressors include polyethylene glycol copolymers, particularly polyethylene glycol polypropylene glycol copolymers. The arrangement of ethylene oxide and propylene oxide of suitable suppressors may be block, alternating, gradient, or random. The polyalkylene glycol may comprise further alkylene oxide building blocks such as butylene oxide. Preferably, the average molecular mass of suitable suppressors exceeds about 2000 g / mol. The starting molecules of suitable polyalkylene glycol may be alkyl alcohols such as methanol, ethanol, propanol, n-butanol and the like, aryl alcohols such as phenols and bisphenols, alkaryl alcohols such as benzyl alcohol, polyol starters such as glycol, glycerin, trimethylol propane, pentaerythritol, sorbitol, carbohydrates such as saccharose, and the like, amines and oligoamines such as alkyl amines, aryl amines such as aniline, triethanol amine, ethylene diamine, and the like, amides, lactams, heterocyclic amines such as imidazol and carboxylic acids. Optionally, polyalkylene glycol suppressors may be functionalized by ionic groups such as sulfate, sulfonate, ammonium, and the like.

[0162] If further suppressors are used, they are typically present in an amount in the range of from about 1 to about 10,000 ppm based on the weight of the bath, and preferably from about 5 to about 10 000 ppm. Preferably no further suppressing agent than the suppressing agent according to the invention is present in the plating bath.

[0163] Leveling agents can advantageously be used in the metal plating baths according to the present invention. The terms "leveling agent” and "leveler” are used herein synonymously. Preferably the composition further comprises at least one leveling agent.

[0164] Suitable leveling agents include, but are not limited to, one or more of polyethylene imine and derivatives thereof, quaternized polyethylene imine, polyglycine, poly (allylamine), polyaniline, polyurea, polyacrylamide, poly(melamine- co-formaldehyde), reaction products of amines with epichlorohydrin, reaction products of an amine, epichlorohydrin, and polyalkylene oxide, reaction products of an amine with a polyepoxide, polyvinylpyridine, polyvinylimidazole as described e.g. in WO 2011 / 151785 A1, polyvinylpyrrolidone, polyaminoamides as described e.g. in WO 2011 / 064154 A2 and WO 2014 / 072885 A2, WO 2019 / 043146 A1, or copolymers thereof, nigrosines, pentamethyl-para-rosaniline hydrohalide, hexamethyl-pararosaniline hydrohalide, di- or trialkanolamines and their derivatives as described in WO 2010 / 069810, and biguanides as described in WO 2012 / 085811 A1. Furthermore, a compound containing a functional group of the formula N-R-S may be used as a leveling agents, where R is a substituted alkyl, unsubstituted alkyl, substituted aryl or unsubstituted aryl. Typically, the alkyl groups are (Ci-Ce)alkyl and preferably (Ci-C4)alkyl. In general, the aryl groups include (C6-C2o)aryl, preferably (Ce-Cio)aryl. Such aryl groups may further include heteroatoms, such as sulfur, nitrogen and oxygen. It is preferred that the aryl group is phenyl or napthyl. The compounds containing a functional group of the formula N-R-S are generally known, are generally commercially available and may be used without further purification. In such compounds containing the N-R-S functional group, the sulfur ("S") and / or the nitrogen ("N") may be attached to such compounds with single or double bonds. When the sulfur is attached to such compounds with a single bond, the sulfur will have another substituent group, such as but not limited to hydrogen, (Ci-Ci2)alkyl, (C2-Ci2)alkenyl, (Ce-C2o)aryl, (Ci-Ci2)alkylthio, 240161W001

[0165] 16

[0166] (C2-Ci2)alkenylthio, (Ce-C2o)arylthio and the like. Likewise, the nitrogen will have one or more substituent groups, such as but not limited to hydrogen, (Ci-Ci2)alkyl, (C2-Ci2)alkenyl, (Cz-Cio)aryl, and the like. The N-R-S functional group may be acyclic or cyclic. Compounds containing cyclic N-R-S functional groups include those having either the nitrogen or the sulfur or both the nitrogen and the sulfur within the ring system.

[0167] In general, the total amount of leveling agents in the electroplating bath is from 0.5 ppm to 10 000 ppm based on the total weight of the plating bath. The leveling agents are typically used in a total amount of from about 0.1 ppm to about 1 000 ppm based on the total weight of the plating bath and more typically from 1 to 100 ppm, although greater or lesser amounts may be used.

[0168] A large variety of further additives may typically be used in the bath to provide desired surface finishes for the Cu plated metal. Usually more than one additive is used with each additive forming a desired function. Advantageously, the electroplating baths may contain one or more of accelerators, levelers, sources of halide ions, grain refiners and mixtures thereof. Most preferably the electroplating bath contains both, an accelerator and a leveler in addition to the suppressor according to the present invention. Other additives may also be suitably used in the present electroplating baths.

[0169] Preferably the composition does not contain any further metals, particularly transition metals, that can be deposited from an aqueous solution other than copper.

[0170] Process

[0171] According to one embodiment of the present invention a copper electroplating bath comprising a composition as described herein may be used for depositing copper on substrates comprising recessed features having an aperture size from 500 nm to 50 m, which features comprise a copper seed layer or other metal seed layer.

[0172] A further embodiment of the present invention is a process for depositing a copper layer comprising the steps

[0173] (a) providing a substrate comprising a recessed feature having an aperture size from 500 nm to 50 pm and an aspect ratio of at least 4, which feature comprises a metal seed layer, such as but not limited to a copper seed layer;

[0174] (b) contacting the composition as described herein with the substrate, and

[0175] (c) applying a current to the substrate for a time sufficient to deposit a metal layer onto the metal seed layer, particularly a copper, and to fill the nanometer sized feature.

[0176] The present invention is useful for depositing a copper layer on a variety of metal seeded substrates, particularly those having nanometer and variously sized apertures. For example, the present invention is particularly suitable for depositing copper on integrated circuit substrates, such as semiconductor devices, with small diameter vias, trenches or other apertures that are provided with a metal seed layer. In one embodiment, semiconductor devices are plated according to the present invention. Such semiconductor devices include, but are not limited to, wafers used in the manufacture of integrated circuits.

[0177] Usually, the metal seed layer has a thickness of 40 nm to 1 .5 nm, preferably of 2 to 10 nm.

[0178] Most preferably features have an aperture size from 500 nm to 50 m and / or an aspect ratio of 4 or more. More preferably the features have an aperture size of 1 pm to 30 pm, most preferably of 1 pm to 20 pm. Preferably the aspect ratio is 6 or more, more preferably 10 or more, particularly 10 to 20 or even more.

[0179] The aperture size according to the present invention means the smallest diameter or free distance of a feature. The terms "aperture” and "opening" are used herein synonymously.

[0180] Typically, substrates are electroplated by contacting the substrate with the plating baths of the present invention. The substrate typically functions as the cathode. The plating bath contains an anode, which may be soluble or insoluble. Optionally, cathode and anode may be separated by a membrane. Potential is typically applied to the cathode.

[0181] Sufficient current density is applied and plating performed for a period of time sufficient to deposit a metal layer, such as a copper layer, having a desired thickness on the substrate. Suitable current densities include, but are not limited to, the range of 0.5 to 250 mA / cm2. Typically, the current density is in the range of 1 to 60 mA / cm2when used to deposit copper in the manufacture of integrated circuits. The specific current density depends on the substrate to be plated, the leveling agent selected and the like. Such current density choice is within the abilities of those skilled in the art. The applied current may be a direct current (DC), a pulse current (PC), a pulse reverse current (PRC) or other suitable current.

[0182] In general, when the present invention is used to deposit metal on a substrate such as a wafer used in the manufacture of an integrated circuit, the plating baths are agitated during use. Any suitable agitation method may be used with the present invention and such methods are well-known in the art. Suitable agitation methods include, but are not limited to, inert gas or air sparging, work piece agitation, impingement and the like. Such methods are known to those skilled in the art. When the present invention is used to plate an integrated circuit substrate, such as a wafer, the wafer may be rotated such as from 1 to 150 RPM and the plating solution contacts the rotating wafer, such as by pumping or spraying. In the alternative, the wafer need not be rotated where the flow of the plating bath is sufficient to provide the desired metal deposit.

[0183] Copper is deposited in apertures according to the present invention without substantially forming voids within the metal copper deposit. By the term "without substantially forming voids", it is meant that 95% of the plated apertures are void-free. It is preferred that 98% of the plated apertures are void-free, mostly preferred is that all plated apertures are void-free. 240161WC01

[0184] 18

[0185] Plating equipment for plating semiconductor substrates are well known. Plating equipment comprises an electroplating tank which holds Cu electrolyte, and which is made of a suitable material such as plastic or other material inert to the electrolytic plating solution. The tank may be cylindrical, especially for wafer plating. A cathode is horizontally disposed at the upper part of tank and may be any type substrate such as a silicon wafer having openings such as trenches and vias. The wafer substrate is coated with a seed layer of metal, such as but not limited to copper. Such metal seed layer may be applied by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD) or the like. An anode is also preferably circular for wafer plating and is horizontally disposed at the lower part of tank forming a space between the anode and cathode. The anode is typically a soluble anode.

[0186] These bath additives are useful in combination with membrane technology being developed by various tool manufacturers. In this system, the anode may be isolated from the organic bath additives by a membrane. The purpose of the separation of the anode and the organic bath additives is to minimize the oxidation of the organic bath additives.

[0187] The cathode substrate and anode are electrically connected by wiring and, respectively, to a rectifier (power supply). The cathode substrate for direct or pulse current has a net negative charge so that Cu ions in the solution are reduced at the cathode substrate forming plated Cu metal on the cathode surface. An oxidation reaction takes place at the anode. The cathode and anode may be horizontally or vertically disposed in the tank.

[0188] Preferably the substrate comprises nanometer sized features and the deposition is performed to at least partly fill the micrometer or nanometer sized features.

[0189] The following examples shall further illustrate the present invention without restricting the scope of this invention.

[0190] Analytical Methods

[0191] The number average molecular weight (Mn) was determined by1H-NMR (Fa.Bruker, 400 MHz) at room temperature (25°C) using DMSO-d6 as deuterated solvent. For processing the spectra, the program MestReNova was used. In doubt, this method is the standard to determine the molecular mass of the suppressing agents according to the invention.

[0192] Alternatively, the molecular mass of the suppressing agents may also be determined by size-exclusion chromatography (SEC). Polystyrene is used as standard and tetrahydrofuran as eluent. The temperature of the column is 30°C, the injected volume 30 pl (pliter) and the flow rate 1.0 ml / min.

[0193] The amine number was determined according to DIN 53176 by titration of a solution of the polymer in acetic acid with perchloric acid. Examples

[0194] Example A: Synthesis of Suppressors

[0195] Several suppressors have been synthesized by polyalkoxylation of the respective starters.

[0196] Example A1 :

[0197] The intermediate product 1 of Example A1 (118.2 g) and potassium tert-butoxide (0.9 g) were placed into a 2 I autoclave. After nitrogen neutralization, the pressure was adjusted to 1.5 bar and the mixture was homogenized at 130 °C for 1 h. Then ethylene oxide (242.3 g) was added at 130 °C over a period of 4 h, reaching a maximum pressure of 4.5 bar. The mixture post-reacted for 6 h at 130 °C. Afterwards styrene oxide (300.4 g) was added at 130°C over a period of 5 h, reaching a maximum pressure of 3.5 bar. To complete the reaction, the mixture post-reacted for 6 h at 130°C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuum at 80 °C. The suppressor was obtained as orange liquid (655 g) with an amine value of 1 .47 mmol / g and a number average molecular mass (Mn) of 1351 g / mol (theoretical 1321 g / mol).

[0198] Example A2:

[0199] The intermediate product 1 of Example A1 (118.2 g) and potassium tert-butoxide (1.2 g) were placed into a 3.5 I autoclave. After nitrogen neutralization, the pressure was adjusted to 1.5 bar and the mixture was homogenized at 130 °C for 1 h. Then ethylene oxide (352.4 g) was added at 130 °C over a period of 6 h, reaching a maximum pressure of 4 bar. The mixture post-reacted for 6 h at 130 °C. Afterwards styrene oxide (300.4 g) was added at 130°C over a period of 5 h, reaching a maximum pressure of 3.5 bar. To complete the reaction, the mixture post-reacted for 6 h at 130°C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuum at 80 °C. The suppressor was obtained as orange liquid (766 g) with an amine value of 1.28 mmol / g and a number average molecular mass (Mn) of 1569 g / mol (theoretical 1541 g / mol).

[0200] Example A3:

[0201] The intermediate product 1 of Example A1 (82.7 g) and potassium tert-butoxide (1 .04 g) were placed into a 3.5 I autoclave. After nitrogen neutralization, the pressure was adjusted to 1.5 bar and the mixture was homogenized at 130 °C for 1 h. Then ethylene oxide (400.9 g) and styrene oxide (210.3 g) were added over a period of 10 h, reaching a maximum pressure of 4.5 bar. To complete the reaction, the mixture post-reacted for 6 h at 130°C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuum at 80 °C. Suppressor 3 was obtained as orange liquid (689 g) with an amine value of 0.97 mmol / g and a number average molecular mass (Mn) of 2058 g / mol (theoretical 1981 g / mol). 240161 W001

[0202] 20

[0203] Example A4:

[0204] A polyethylene imine with a molecular mass of 2000 g / mol (709.5 g) was placed under nitrogen atmosphere into a 3.5 1 autoclave and heated up to 100 °C. Then ethylene oxide (726.8 g) was added over a period of 12 h, reaching a maximum pressure of 5 bar. The mixture post-reacted for 6 h. The orange intermediate product 2 (1430 g) having an amine number of 8.85 mmol / g was obtained.

[0205] The intermediate product 2 above (87 g) and potassium tert-butoxide (1.3 g) were placed into a 3.5 1 autoclave. After nitrogen neutralization, the pressure was adjusted to 1 .5 bar and the mixture was homogenized at 130 °C for 1 h. Then ethylene oxide (528.6 g) was added at 130 °C over a period of 9 h, reaching a maximum pressure of 5.5 bar. The mixture post-reacted for 6 h at 130 °C. Afterwards styrene oxide (240.3 g) was added at 130°C over a period of 4 h, reaching a maximum pressure of 3.5 bar. To complete the reaction, the mixture post-reacted for 6 h at 130°C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuum at 80 °C. The suppressor was obtained as orange liquid (852 g) with an amine value of 0.94 mmol / g and a number average molecular mass (Mn) of 44.837 g / mol (theoretical 39797 g / mol).

[0206] Example A5:

[0207] A polyethylene imine with a molecular mass of 2000 g / mol (667.1 g) was placed under nitrogen atmosphere into a 3.5 I autoclave and heated up to 100 °C. Then ethylene oxide (682.8 g) was added over a period of 11 h, reaching a maximum pressure of 8.5 bar. The mixture post-reacted for 6 h. The orange intermediate product 3 (1332 g) having an amine number of 9.6 mmol / g was obtained.

[0208] The intermediate product 3 above (87.1 g) and potassium tert-butoxide (1.3 g) were placed into a 3.5 1 autoclave. After nitrogen neutralization, the pressure was adjusted to 1 .5 bar and the mixture was homogenized at 130 °C for 1 h. Then ethylene oxide (528.6 g) was added at 130 °C over a period of 10 h, reaching a maximum pressure of 5.5 bar. The mixture post-reacted for 6 h at 130 °C. Afterwards styrene oxide (240.3 g) was added at 130°C over a period of 4 h, reaching a maximum pressure of 3.5 bar. To complete the reaction, the mixture post-reacted for 6 h at 130°C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuum at 80 °C. The suppressor was obtained as orange liquid (853 g) with an amine value of 0.99 mmol / g and a number average molecular mass (Mn) of 18.802 g / mol (theoretical 15919 g / mol).

[0209] Example B: Copper electroplating experiments

[0210] 5*50 pm substrates were used for regular screening with Cu Seed: 500 nm at the unplated overburden and >10 nm seed at the via bottom. Ta / Ta N was used as a barrier. 240161W001

[0211] 21

[0212] A copper plating bath was prepared by combining 60 g / l copper as copper sulfate, 60 g / l sulfuric acid, 50 ppm chloride ions, the specified amount of the respective suppressor prepared in examples A1 to A5, and 0.007 g / l of SPS and DI water.

[0213] Prior electroplating the substrate possessing holes with a diameter of about 5 micrometers and a depth of about 50 pm was immersed in Dl-Water including an ultrasonic process for 5 min for complete wetting of the vias.

[0214] After wetting the substrate was immersed in the above-described plating bath and a waiting period of 5 s was applied. After this period copper was electroplated onto the wafer substrate by contacting the substrate at 25 °C applying a direct current of -1.2 mA / cm2for 30 min and rotated with 30 rpm. The thus electroplated copper was investigated by optical microscopy after manual polishing of the substrate.

[0215] The results are depicted in Table 1 and shown in Figs 1 to 3. The aromatic content m / (o+m) is the molar content of styrene oxide in the oxyethylene-co-oxystryrene copolymer side chains without starter. The molar aromatic content was calculated based on the molar amount of styrene oxide present in the whole suppressor additive including the amine starter.

[0216] Table 1

[0217] *Note: block = EO followed by StO; random = statistical EO / StO copolymer

[0218] Table 1 shows that all tested suppressors show a defect free filling. It also shows a significant influence of the aromatic content in the suppressor. When comparing the examples with suppressors of different aromatic content, it is eminent that a higher aromatic content leads to a better filling performance.

Claims

Claims1 . An acidic aqueous composition for copper electroplating comprising(a) copper ions;(b) at least one additive of formula S1whereinXs1is selected from a linear, branched or cyclic C1-C12 alkanediyl, which may be substituted or unsubstituted, and which may optionally be interrupted by 0, S or NRS40;RS1is selected from (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)mH, -Xs4-N[-(C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)m]2, Zs, XS5-ZS, XS4-N(ZS)2;Rs2is selected from H, Rs1, or Rs40;Rs3is selected from H, Rs1, Rs4°; or Rs3and an adjacent group Rs4together form a divalent group Xs2;Rs4is selected from H, Rs1, Rs4°; or, if n>3, may be As1, or, if n>2, two adjacent groups Rs4may together form a divalent group Xs2;Rs5is (a) a Ce to C15 carbocyclic aromatic group or a C5 to C14 heterocyclic aromatic group in which one or two carbon atoms are substituted by N atoms, and which carbocyclic or heterocyclic aromatic group or is unsubstituted or substituted by one or more alkyl or alkoxy or(b) a Ci to Ce alkyl that is substituted by a Ce to C15 carbocyclic aromatic group or a C5 to C14 heterocyclic aromatic group in which one or two carbon atoms are substituted by N atoms, and which carbocyclic or heterocyclic aromatic group or is unsubstituted or substituted by one or more alkyl or alkoxy;Rs6is methyl or ethyl;Rs4° is a linear or branched Ci-C2o alkyl, which may optionally be substituted by hydroxy, alkoxy, or alkoxycarbonyl;Xs2is selected from a linear or branched C1-C12 alkanediyl, which may be substituted or unsubstituted, and which may optionally be interrupted by 0, S or NRS40; andXs3is a linear or branched Ci to C12 alkanediyl, which may be interrupted by 0 and S atoms or substituted by O-Rs31;Xs4is a linear or branched Ci to C12 alkanediyl;Xs5is a divalent group comprising at least one C2 to Ce polyoxyalkylene;Rs31, Rs32are independently selected from (a) (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)mor (b) a further branching group to form a multiple branching group (ZsP)p(Rs31aRs32a)2P, wherein Rs31aand Rs32aare independently selected from (C2H4-O)o(C2H3Rs6-O)k(C2H3Rs5-O)m;ZSP is selected fromorm is an integer of from 1 to 200 is an integer of from 1 to 100; k is an integer of from 0 to 10; n is an integer of from 1 to 600, preferably 1 to 50. s is an integer from 1 to 200, where s is counted for n; p is an integer of from 2 to 4. wherein m / (o+k+m) is 3 to 30 % and wherein k / (o+k+m) is 10 % or below.

2. The composition according to claim 1 , wherein Xs1is selected from(a) a Ci-Ce alkanediyl, preferably methanediyl, ethanediyl or propanediyl, and(b) -(CH2)q-[Q-(CH2)r]s-, wherein Q is selected from O, S or NR40, q and r are integers from 1 to 6, s is an integer from 1 to 4 and q + r x s is the total number of C atoms in Xs1.

3. The composition according to anyone of the preceding claims, wherein n is from 1 to 5, preferably 1 to 3.

4. The composition according to claims 3, wherein the number average molecular mass Mnof the additive is from 500 to 6 000 g / mol, preferably from 1 200 to 4 000 g / mol.

5. The composition according to anyone of claims 1 to 2, wherein n is from 6 to 600, preferably 20 to 300.

6. The composition according to claims 5, wherein the number average molecular mass Mnof the additive is from 10 000 to 80 000 g / mol, preferably from 20 000 to 50 000 g / mol.

7. The composition according to anyone of the preceding claims, wherein the sum o+k+m is from 5 to 40, preferably from 10 to 30.

8. The composition according to anyone of the preceding claims, wherein Rs2, Rs3, Rs4are independently selected from Rs1.

9. The composition according to anyone of the preceding claims, wherein Rs5is a Ce to C15 carbocyclic aromatic group selected from phenyl, 2-, 3-, or 4-alkylphenyl, particularly 2- or 4-toluyl, alkoxyphenyl, particularly, methoxyphenyl, dialkylphenyl, particularly xylyl, naphtyl, benzyl, 2-phenyl-eth-1-yl.

10. The composition according to claim 9, wherein Rs5is selected from phenyl, 2- or 4-toluyl, methoxyphenyl, xylyl, or naphtyl.11 . The composition according to anyone of claims 1 to 8, wherein Rs5is a Ce to C15 N-heteroccyclic aromatic group selected from 2-, 3-, or 4-pyridinyl, pyrrolyl, indolyl, or 1 -imidazolyl.

12. The composition according to anyone of the preceding claims, comprising an additive of formula (S2a)or an additive of formula (S2d)whereinRs1, n, have the prescribed meanings;Rs2, Rs3and Rs4are independently RS1or Rs4°, preferably Rs1;Xs1, Xs11, Xs2are independently a Ci to C3 alkanediyl; and r is an integer from 1 to 8, preferably from 2 to 6.

13. The composition according to anyone of the preceding claims, whereinRS1is (C2H4-O)o-(C2H3RS5-O)m-H,Rs2, Rs3and Rs4are Rs1;Xs1is a Ci to C3 alkanediyl; and m is an integer of from 4 to 25.

14. The composition according to anyone of the preceding claims, wherein the additive is received by reacting ethylene diamine, diethylene triamine, triethylene tetramine or a polyethyleneimine having a number-average molecular mass of from 500 to 2000 g / mol with ethylene oxide and styrene oxide in any order or in mixture.

15. The composition according to anyone of the preceding claims, further comprising halide ions, particularly chloride ions, in a concentration of from 10 to 100 ppm, preferably from 20 to 80 ppm.

16. The composition according to anyone of the preceding claims, further comprising an accelerator comprising one or more sulfidic sulfur atoms and one or more sulfonic or phosphonic acid group, combinations thereof, or their salts.

17. Use of a copper electroplating bath comprising a composition according to anyone of claims 1 to 12 for depositing copper on substrates comprising a recessed feature having an aperture size from 500 nm to 50 m and an aspect ratio of at least 4, which feature comprises a metal seed layer, particularly a copper seed layer.

18. A process for depositing a copper layer comprising the steps(a) providing a substrate comprising a recessed feature having an aperture size from 500 nm to 50 pm and an aspect ratio of at least 4, which feature comprises a metal seed layer;(b) contacting a composition according to any one of claims 1 to 16 with the substrate, and(c) applying a current to the substrate for a time sufficient to deposit a copper layer onto the metal seed layer and to fill the recessed feature at least partly.

19. The process according to claim 18, wherein the feature is a through silicon via.

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