WO2018073011A1

WO2018073011A1 - Composition for metal plating comprising suppressing agent for void free submicron feature filling

Info

Publication number: WO2018073011A1
Application number: PCT/EP2017/075294
Authority: WO
Inventors: Marcel Patrik KIENLE; Dieter Mayer; Marco Arnold; Alexandra Haag; Charlotte Emnet; Alexander Fluegel
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2016-10-20
Filing date: 2017-10-05
Publication date: 2018-04-26
Anticipated expiration: 2019-04-20
Also published as: TW201823520A

Abstract

A composition comprising metal ions and at least one compound of formula I (I) wherein X¹ and X² are independently selected from a chemical bond and straight chain or branched C₁-C₁₈ alkanediyl, which may optionally be interrupted by O, S and NR¹⁰, X³ and X⁴ are independently selected from straight chain or branched C₁-C₁₈ alkanediyl, which may optionally be interrupted by O, S and NR¹⁰, R³ is selected from R¹, NR¹R² and C₁-C₂₀ alkyl, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl, Z is selected from NR¹R² and, if X¹ is a chemical bond, from R¹, R¹ and R² are independently selected from a copolymer of ethylene oxide and at least one further C₃ to C₁₂ alkylene oxide or styrene oxide, R¹⁰ is selected from (a) H, (b) C₁-C₂₀ alkyl, which may optionally be substituted by hydroxyl, alkoxy or alkoxycarbonyl, and (c) C₁-C₂₀ alkenyl, which may optionally be substituted by hydroxyl, alkoxy or alkoxycarbonyl.

Description

Composition for metal plating comprising suppressing agent for void free submicron feature filling

The present invention relates to a composition for metal plating, particular copper electroplating, comprising metal ions and a suppressing agent.

Background of the Invention

Filling of small features, such as vias and trenches, by metal, in particular 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 copper

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 copper lines. One class of additives are the so-called suppressors or suppressing agents.

Suppressors are used to provide a substantially bottom-up filling of small features like vias or trenches. The smaller the features are 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.

US 2005/0072683 A1 discloses high molecular weight surfactants inhibiting the electrodeposition like alkyl polyoxyethylene amines, particularly ethylenediamine ethylene oxide (EO) propylene oxide (PO) block copolymers in combination with a further polyethylene glycol (PEG) suppressor.

WO2004/016828 A2 discloses additives called antimisting agents prepared by polyalkoxylation of amine compounds like triethanolamine, ethylenediamine or diethylenetriamine. Alkoxylated triethanolamine compounds were mentioned to be preferred and were used in the examples.

US 2006/0213780 A1 discloses amine-based copolymers of EO/PO copolymers having at least 70% PO content. The copolymers are mentioned to have block, alternating or random structure. A preferred amine is ethylenediamine.

US 6,444,1 10 B2 discloses an electroplating solution which may comprise, besides a huge variety of additives called surfactants, nitrogen containing additives like ethoxylated amines, polyoxyalkylene amines, alkanol amines, amides like those provided by BASF under the trademark TETRONIC ^®. US 2002/0043467 A1 , US 2002/0127847 A1 and US 4,347,108 A disclose, as suppressors, compounds provided by BASF under the trademark TETRONIC ^® or PLURONIC ^®. WO 2006/053242 A1 discloses amine-based polyoxyalkylene suppressors. The amine may be methylamine, ethylamine, propylamine, ethylendiamine, diethylenetriamine, diaminopropane, diethyleneglykol diamin or triethylenglycol diamine. The copolymers may have block, alternating or random structure. Compounds provided by BASF under the trademark TETRONIC ^®, all of those being EO/PO block copolymers of ethylene diamine, and having a molecular mass of up to 5500 g/mol are described to be preferred. The block copolymers of EO and PO are used in the examples .

US 2005/0045485 A1 discloses amine-based polyalkylene oxide copolymers, including diamines, triamines.

US 2012/018310 A1 , US 2012/027948 A1 , and US 2012/02471 1 A1 disclose compositions comprising suppressors based on particular amine started

polyalkoxyalkylene copolymers. With further decreasing aperture size of the features like vias or trenches to dimensions of below 30 nanometers and even below 10 nanometers, respectively, the filling of the interconnects with copper becomes especially challenging, also since the copper seed deposition prior to the copper electrodeposition might exhibit inhomogeneity and nonconformity and thus further decreases the aperture sizes particularly at the top of the apertures. Especially apertures with a seed overhang at the top opening or convex- shaped apertures are challenging to fill and require an especially effective copper growth suppression at the side wall of the feature and the opening of the aperture.

Other metals like cobalt are discussed to be an alternative to copper.

Even if there exist many types of amine started polyalkoxyalkylene copolymer suppressors there is still a need for suppressors which are capable of filling features having aperture sizes of 15 nm, particularly 10 nm or below. It is therefore an object of the present invention to provide a copper electroplating additive having good superfilling properties, in particular suppressing agents capable of providing a substantially voidless and seamless filling of features on the nanometer and on the micrometer scale with a metal electroplating bath, preferably a copper electroplating bath. It is a further object of the present invention to provide a metal electroplating additive capable of providing a substantially voidless and seamless filling of features having a convex shape. Summary of the Invention

Surprisingly, it has now been found, that the use of amine-based polyoxyalkylene suppressing agents based on cyclic amines show extraordinary superfilling properties, particularly when used to fill in features having extremely small aperture sizes and/or high aspect ratios. The present invention provides a new class of highly effective, strong suppressing agents that cope with the seed overhang issue and provide substantially defect free trench filling despite a non-conformal metal seed. Therefore, the present invention provides a composition comprising metal ions and at least one compound of formula I

x³

R X²- -N N- -X- (i) x⁴

wherein

X¹ and X² are independently selected from a chemical bond and straight chain or branched C1-C18 alkanediyl, which may be substituted or unsubstituted, and which may optionally be interrupted by O, S and NR¹⁰,

X³ and X⁴ are independently selected from straight chain or branched C1-C18

alkanediyl, which may be substituted or unsubstituted, and which may optionally be interrupted by O, S and NR¹⁰,

R³ is selected from R¹, NR¹R² and C1-C20 alkyl, which may optionally be

substituted by hydroxy, alkoxy or alkoxycarbonyl, Z is selected from NR¹R² and, if X¹ is a chemical bond, from R¹,

R¹ and R² are independently selected from a copolymer of ethylene oxide and at least one further C3 to C12 alkylene oxide or styrene oxide, R¹⁰ is selected from (a) H, (b) C1-C20 alkyl, which may optionally be substituted by hydroxyl, alkoxy or alkoxycarbonyl, and (c) C1-C20 alkenyl, which may optionally be substituted by hydroxyl, alkoxy or alkoxycarbonyl.

The invention further relates to the use of a metal plating bath comprising a

composition as defined herein for depositing the metal on substrates comprising features having an aperture size of 30 nanometers or less, in particular 20 nm or less, 15 nm or less or even 10 nm or less and/or an aspect ratio of 4 or more. The invention further relates to a process for depositing a metal layer on a substrate comprising nanometer-sized features by

a) contacting a composition as defined herein with the substrate, and

b) applying a current density to the substrate for a time sufficient to deposit a metal layer onto the substrate,

wherein the substrate comprises nanometer sized features and the deposition is performed to fill the micrometer or nanometer sized features. In this way suppressing agents are provided that result in a extraordinarily pronounced bottom-up fill metal, particularly copper growth while perfectly suppressing the sidewall metal growth, both leading to a flat growth front and thus providing substantially defect free trench or via fill. The strong sidewall metal growth suppression of the invention enables non-conformal metal seeded features to be substantially void free filled.

Moreover the invention provides an overall homogeneous bottom-up fill in neighboring features of dense feature areas.

The suppressing agents according to the present invention are particularly useful for filling of small features, particularly those having aperture sizes of 30 nanometer or below.

Brief description of the Figures

Fig. 1 a, b show SEM images of partly and fully filled trenches after copper

electroplating according to example 9;

Fig. 2a, b show SEM images of partly and fully filled trenches after copper

electroplating according to example 10

Fig. 3a, b show SEM images of partly and fully filled trenches after copper

electroplating according to example 1 1

Fig. 4a, b show SEM images of partly and fully filled trenches after copper

electroplating according to example 12

Fig. 5a, b show SEM images of partly and fully filled trenches after copper

electroplating according to example 13

Fig. 6a, b show SEM images of partly and fully filled trenches after copper

electroplating according to example 14

Fig. 7a, b show SEM images of partly and fully filled trenches after copper

electroplating according to example 15

Fig. 8a, b show SEM images of partly and fully filled trenches after copper

electroplating according to example 16 Detailed Description of the Invention

Suppressors according to the invention The composition for metal electroplating according to the invention comprises at least one suppressing agent as described below.

Besides metal ions the composition according to the present invention comprises at least one compound of formula I:

In one embodiment Z is NR¹R² to form compounds of formula la:

In another embodiment Z is R¹ and X¹ is a chemical bond (or in other words: X¹-Z is R ).

Such compound, in the following also referred to as "suppressing agent", is generally obtainable by reacting a cyclic amine compound with the respective alkylene oxides to form oxyalkylene side chains R¹, R² and optionally R³ attached to the cyclic amine compound.

Such copolymers of ethylene oxide and at least one further C3 to C6 alkylene oxide may have random, block, alternating, gradient, or any other arrangement.

As used herein, "random" means that the respective comonomers are polymerized from a mixture and therefore arranged in a statistically manner depending on their copoymerization parameters.

As used herein, "block" means that the respective comonomers are polymerized after each other to form blocks of the respective co-monomers in any predefined order. By way of example, for EO and propylene oxide (PO) comonomers such blocks may be, but are not limited to: -EO_x-PO_y, -PO_x-EO_y, -EO_x-PO_y-EO_x, -PO_x-EO_y-PO_x, etc.

In the following, the cyclic amine compound is also referred to as the "amine starter". In a preferred embodiment Z is NR¹R²; X¹ and X² are selected from a chemical bond; X³ and X⁴ are independently selected from straight chain or branched Ci-Cs alkanediyi, which may optionally be interrupted by O and NR¹⁰; R¹, R², R³ are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide; and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

In another preferred embodiment Z is NR¹R²; X¹ and X² are independently selected from straight chain or branched Ci-Cs alkanediyi, which may optionally be interrupted by O and NR¹⁰; X³ and X⁴ are independently selected from straight chain Ci-Cs alkanediyi, which may optionally be interrupted by O and NR¹⁰; R¹ and R² are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide; R³ is selected from NR¹R²; and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl. In yet another preferred embodiment Z is NR¹R²; X¹ is selected from straight chain or branched Ci-Cs alkanediyi, which may optionally be interrupted by heteroatoms or divalent groups selected from O and NR¹⁰; X² is selected from a chemical bond; X³ and X⁴ are independently selected from straight chain Ci-Cs alkanediyi, which may optionally be interrupted by O and NR¹⁰; R¹, R², R³ are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide; and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

In yet another preferred embodiment Z is NR¹R²; X¹ is selected from straight chain or branched Ci-Cs alkanediyi, which may optionally be interrupted by O and NR¹⁰; X² is selected from a chemical bond; X³ and X⁴ are independently selected from straight chain Ci-Cs alkanediyi, which may optionally be interrupted by O and NR¹⁰; R¹, R² are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide; R³ is selected from Ci-Cs alkyl, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl, preferably methyl or ethyl; and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

In yet another preferred embodiment Z is NR¹R²; X¹ and X² are selected from a chemical bond; X³ and X⁴ are independently selected from straight chain or branched Ci-Cs alkanediyi, which may optionally be interrupted by O and NR¹⁰; R¹ and R² are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide; R³ is selected from Ci-Cs alkyl, preferably methyl or ethyl; and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

In yet another preferred embodiment R³ and Z are independently selected from NR¹R²; X¹ and X² are selected from a chemical bond; X³ and X⁴ are independently selected from straight chain or branched Ci-Cs alkanediyi, which may optionally be interrupted by O and NR¹⁰; R¹ and R² are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide; and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

In yet another preferred embodiment Z is R¹; X¹ and X² are selected from a chemical bond; X³ and X⁴ are independently selected from straight chain or branched Ci-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰; R¹ is selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide; R³ is selected from Ci-Cs alkyl, preferably methyl or ethyl; and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

In yet another preferred embodiment Z is R¹; X¹ and X² are selected from a chemical bond; X³ and X⁴ are independently selected from straight chain or branched Ci-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰; R¹ is selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide; R³ is R¹; and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

As used herein, "chemical bond" means that the respective moiety is not present but that the adjacent moieties are bridged so as to form a direct chemical bond between these adjacent moieties. By way of example, if in X-Y-Z the moiety Y is a chemical bond then the adjacent moieties X and Z together form a group X-Z.

As used herein, "C_x" means that the respective group comprises x numbers of C atoms. Preferably X¹ and X² are independently selected from straight chain or branched C2 to Cs alkanediyl, which may be substituted or unsubstituted, preferably unsubstituted. Even more preferably X¹ and X² are independently selected from C2 to C6 alkanediyl, even more preferably from C2 to C₄ alkanediyl, all of which may optionally be interrupted by O and NR¹⁰. Most preferably X¹ and X² are selected from ethanediyi and propanediyi. In a preferred embodiment X¹ and X² are free from chlorine (CI) substituents.

Preferably X³ and X⁴ are independently selected from straight chain or branched C2 to C₄ alkanediyl, which may be substituted or unsubstituted, preferably unsubstituted. Most preferably X³ and X⁴ are independently selected from ethanediyi and propanediyi. In a particularly preferred embodiment X³ and X⁴ are both ethanediyi, or X³ is methanediyl and X⁴ is propanediyi.

If present, R¹⁰ is preferably selected from H and C1-C10 alkyl more preferably from H and Ci-C₄ alkyl, most preferably from H and methyl or ethyl. In a preferred embodiment the further C3 to C6 alkylene oxide is selected from propylene oxide and 1 ,2-butylene oxide or any isomers thereof. In another preferred embodiment the C3 to C₄ alkylene oxide is selected from propylene oxide (PO). In this case EO/PO copolymer side chains are generated starting from the active amino functional groups of the amine starter.

Generally, the content of ethylene oxide in R¹ and, if applicable, R² and R³ may be from 5 to 95 % by weight. Preferably the content of ethylene oxide in R¹ and, if applicable, R² and R³ is from 20 to 80 % by weight, even more preferably from 25 to 70 % by weight, most preferably from 30 to 60 % by weight, all based on the total amount of alkylene oxides in the additive (i.e. without amine starter and further modifications).

Generally the molecular weight M_w of the suppressing agent may be from about 500 to about 25000 g/mol, preferably 2000 to 15000 g/mol. In one embodiment the molecular weight M_w of the suppressing agent is from about 500 to about 8000 g/mol, in particular from about 2000 to about 6000 g/mol. In another preferred embodiment the molecular weight M_w of the suppressing agent is from about 5000 to about 20000 g/mol, in particular from about 6000 to about 15000 g/mol. Plating Bath

A wide variety of metal plating baths may be used with the present invention. Metal electroplating baths typically contain a metal ion source, an electrolyte, and the suppressing agent.

The metal ion source may be any compound capable of releasing metal ions to be deposited in the electroplating bath in sufficient amount, i.e. is at least partially soluble in the electroplating bath. Suitable metal ions include, but are not limited to, tin, silver(optionally in combination with tin), copper, and cobalt. In a preferred

embodiment, the metal comprises or consist of copper or cobalt. A particularly preferred metal comprises or consists of copper. In other preferred embodiment the metal comprises copper and comprise tin in amount of below 0.1 g/l, preferably below 0.01 g/l, most preferably no tin. It is preferred that the metal ion source is soluble in the plating bath to release 100 % of the metal ions. Suitable metal 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.

Besides metal electroplating the compositions may be used in electroless deposition of metal containing layers. The compositions may particularly used in the deposition of barrier layers containing Ni, Co, Mo, W and/ or Re. In this case, besides metal ions, further elements of groups III and V, particularly B and P may be present in the composition for electroless deposition und thus co-deposited with the metals. The metal ion source may be used in the present invention in any amount that provides sufficient metal ions for electroplating on a substrate.

If the metal is copper, it is typically present in an amount in the range of from about 1 to about 300 g/l of the plating solution. Generally the suppressor is useful in low copper, medium copper and high copper baths. Low copper means a copper concentration from about 1 to about 20 g/l.

Also mixtures of metal salts may be electroplated according to the present invention. Thus, alloys, such as copper-tin having up to about 2 percent by weight tin, may be advantageously plated according to the present invention. The amounts of each of the metal salts in such mixtures depend upon the particular alloy to be plated and is well known to those skilled in the art.

In general, besides the metal ions and at least one of the suppressing agents according to the present invention the present metal electroplating compositions preferably include an electrolyte, typically an acidic or alkaline electrolyte, one or more sources of metal ions, optionally halide ions, and optionally other additives like accelerators and/or levelers. Such baths are typically aqueous. The water may be present in a wide range of amounts. Any type of water may be used, such as distilled, deionized or tap.

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.

Typically, the plating baths of the present invention may be used at any temperature from 10 to 65 degrees C or higher. It is preferred that the temperature of the plating baths is from 10 to 35 degrees C and more preferably from 15 degrees to 30 degrees C. Suitable 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, tetraalkylammonium hydroxide, preferably tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide and the like. In a peraticular embodiment the electrolyte does not comprise pyrophosphoric acid. Acids are typically present in an amount in the range of from about 1 to about 300 g/IThe plating bath may be a high, a medium or a low acid bath. Low acid baths usually comprise one or more acids in a concentration below 15 g/l. The pH of the acidic plating bath is usually below 5, preferably below 4, even more preferably below 3, most preferably below 2. Alkaline electrolytes are typically present in an amount of about 0.1 to about 20 g/l or to yield a pH of 8 to 13 respectively, and more typically to yield a pH of 9 to 12. Such electrolytes may optionally contain a source of halide ions, such as chloride ions as in metal chloride, preferably copper chloride, or hydrochloric acid. A wide range of halide ion concentrations may be used in the present invention such as from about 0 to about 500 ppm. Typically, the halide ion concentration is in the range of from about 10 to about 100 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. In a particular embodiment the suppressors of this invention may be used in low copper electrolyte compositions typically containing about below 20 g/l copper ions, in combination with typically about 2-15 g/l acid like sulfuric acid and with halide ions typically in the range of about 10-400 ppm by weight, preferably with chloride ions. Other additives

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.

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 sulphur atom and a sulfonic/phosphonic acid or their salts. Preferably the composition further comprises at least one

accelerating agent.

Preferred accelerators have the general structure M03X-R²¹-(S)_n-R²², with: M is a hydrogen or an alkali metal (preferably Na or K)

- X is P or S

- n = 1 to 6

R²¹ is selected from Ci-C₃ alkyl group or heteroalkyl group, an aryl group or a heteroaromatic group. Heteroalkyl groups will have one or more heteroatom (N,

S, O) 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.

- R²² is selected from H or (-S-R^{21 '}X0₃M), with R^{21 '} being identical or different from R²¹.

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

M0₃S-R²¹-SH

M0₃S-R²¹-S-S-R²¹'-S0₃M

M0₃S-Ar-S-S-Ar-S0₃M

with R²¹ is as defined above and Ar is Aryl.

Particularly preferred accelerating agents are:

- SPS: bis-(3-sulfopropyl)-disulfide disodium salt

MPS: 3-mercapto-1 -propansulfonic acid, sodium salt

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-(ro-sulphopropyl)-disulfide, disodium salt; methyl-(ro-sulphopropyl)-trisulfide, disodium salt.

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.

Any additional suppressor may be advantageously used in the present invention.

Suppressors useful in the present invention include, but are not limited to, polymeric materials, particularly those having heteroatom substitution, and more particularly oxygen substitution. It is preferred that the suppressor is a polyalkyleneoxide. Suitable 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 weight 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.

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.

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.

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 W01 1 151785 A1 , polyvinylpyrrolidone, polyaminoamides as described e.g. in W01 1064154A2 and W014072885 A2, 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

W01208581 1 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, (C₆-C2o)aryl, (Ci-Ci₂)alkylthio, (C₂-Ci₂)alkenylthio, (C₆-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, (C₇-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.

In general, the total amount of leveling agents in the electroplating bath is from 0.5 ppm to 10000 ppm based on the total weight of the plating bath. The leveling agents according to the present invention are typically used in a total amount of from about 0.1 ppm to about 1000 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.

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. Process

According to one embodiment of the present invention a metal plating bath comprising a composition as described above is used for depositing the metal on substrates comprising features having an aperture size of 30 nanometers or less.

A further embodiment of the present invention is a process for depositing a metal layer on a substrate by

a) contacting a metal plating bath comprising a composition according to the

present invention with the substrate, and

b) applying a current density to the substrate for a time sufficient to deposit a metal layer onto the substrate.

The present invention is useful for depositing a metal layer, particularly a copper layer, on a variety of substrates, particularly those having submicron 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. 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.

Preferably the substrate comprises submicrometer sized features and the deposition is performed to fill the submicrometer sized features. Most preferably the submicrometer- sized features have an (effective) aperture size from 1 to 30 nanometers and/or an aspect ratio of 4 or more. More preferably the features have an aperture size of 25 nanometers or below, most preferably of 20 nanometers or below. The aperture size according to the present invention means the smallest diameter or free distance of a feature before plating, i.e. after copper seed deposition. The terms "aperture" and "opening" are used herein synonymously. A convex shape is a feature having an aperture size being at least 25 %, preferably 30 %, most preferably 50 % smaller than the biggest diameter or free distance of the feature before plating.

The agents/additives according to the present invention can further advantageously be used for electroplating of copper in through silicon vias (TSV). Such vias normally have diameters of several micrometers up to 100 micrometers and large aspect ratios of at least 4, sometimes above 10.

Furthermore the agents/additives according to the present invention can

advantageously be used in bonding technologies such as the manufacture of copper pillars or tin or tin/silver solder bumps of typically 50 to 100 micrometers height and diameter for the bumping process, in circuit board technologies like the manufacture of high-density-interconnects on printed circuit boards using microvia plating or plated- through-hole technologies, or in other packaging processes for electronic circuits.

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. 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 1 to 250 mA/cm². Typically, the current density is in the range of 1 to 60 mA/cm² when 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. 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.

The metal, particularly copper, tin and cobalt, is deposited in apertures according to the present invention without substantially forming voids within the metal 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.

While the process of the present invention has been generally described with reference to semiconductor manufacture, it will be appreciated that the present invention may be useful in any electrolytic process where metal filled small features that are substantially free of voids are desired. Such processes include printed wiring board manufacture. For example, the present plating baths may be useful for the plating of vias, pads or traces on a printed wiring board, as well as for bump plating on wafers. Other suitable processes include packaging and interconnect manufacture. Accordingly, suitable substrates include lead frames, interconnects, printed wiring boards, and the like.

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 typically coated with a seed layer of Cu or other metal or a metal containing layer to initiate plating thereon. A Cu 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. 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.

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.

Metal, particularly copper, is deposited in apertures according to the present invention without substantially forming voids within the metal deposit. By the term "without substantially forming voids", it is meant that 95% of the plated apertures are void-free. It is preferred that the plated apertures are void-free.

Preferably the substrate comprises nanometer sized features and the deposition is performed to fill the micrometer or nanometer sized features, particularly those having an aperture size from 1 to 30 nm and/or an aspect ratio of 4 or more. The suppressors are even capable of void-free filling features having aperture sizes of 15 nm, particularly 10 nm or below and aspect ratios of 4 or more.

While the process of the present invention has been generally described with reference to semiconductor manufacture, it will be appreciated that the present invention may be useful in any electrolytic process where a substantially void-free copper deposit is desired. Accordingly, suitable substrates include lead frames, interconnects, printed wiring boards, and the like.

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.

The following examples shall further illustrate the present invention without restricting the scope of this invention. Examples

Several N-containing EO-PO copolymers have been synthesized by polyalkoxylation of the respective N-containing cyclic starting molecules. The compositions of the suppressors are given in Table 1 .

Table 1 Preparation Starter EO PO BuO Structure Mw Fill Example number number number [g/mol] perfor(Plating / starter / starter / starter mance Example)

1 ,4-Bis(3-

2 (10) aminopropyl) 120 120 0 random 12456 + piperazine

1 ,4-Bis(3-

PO-EO-

3 (1 1 ) aminopropyl) 65 65 0 6830 +

Block

piperazine

N-(2-

PO-EO-

1 (9) aminoethyl) 65 65 0 6760 +

Block

piperazine

1 ,4-Bis(3-

6 (14) aminopropyl) 71 0 30 random 5484 + piperazine

1 ,4-Bis(3-

7 (15) aminopropyl) 15,7 27,8 0 random 2500 + piperazine

1 -Amino-4-

PO-EO-

4 (12) methyl- 16 30,4 0 2582 +

Block

piperazine

N-Methyl PO-EO-

5 (13) 30 30 0 3163 + piperazine Block

8 (16) Piperazine 65 65 0 random 6724 +

The amine number was determined according to DIN 53176 by titration of a solution of the polymer in acetic acid with perchloric acid. Example 1 : Synthesis of suppressor 1

N-(2-aminoethyl)piperazine (356 g) and water (17.8 g) were placed into a 3.5 L autoclave at 80 °C. After nitrogen neutralization propylene oxide (480 g) was added in portions at 90 °C over a period of 7 h 30 min. To complete the reaction, the mixture was allowed to post-react for 6 h. Then, the reaction mixture was stripped with nitrogen. Water and volatile organic compounds were removed in vacuo at 100°C. A highly viscous light yellow intermediate product (825 g) having an amine number of 9.56 mmol/g was obtained.

The intermediate product (56.6 g) and aqueous potassium hydroxide solution

(concentration: 50 w% KOH; 7.5 g) were placed into a 3.5 I autoclave at 80 °C. After nitrogen neutralization the solvent was removed for 2 h at 120 °C under vacuo (< 10 mbar). Then, the pressure was increased to 2 bar and propylene oxide (671 g) and was added at 140 °C over a period of 8 h, followed by a post-reaction for 8 h at the same temperature. Subsequently, ethylene oxide (534 g) and was added at 140 °C over a period of 8 h. To complete the reaction, the mixture was allowed to post-react for 6 h at 140 °C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuo at 80 °C. Suppressor 1 was obtained as a light brown liquid (1280 g) having an amine number of 0.49 mmol/g. Example 2: Synthesis of suppressor 2

1 ,4-Bis(3-aminopropyl)piperazine (449 g) was placed into a 2 L autoclave. After nitrogen neutralization the vessel was heated to 100 °C and ethylene oxide (395 g) was added over a period of 4 h reaching a maximum pressure of 7 bar. To complete the reaction, the mixture was allowed to post-react for 6 h. Then, the reaction mixture was cooled to 80 °C and stripped with nitrogen. The intermediate product was obtained as a colourless oil (825 g) having an amine number of 10.87 mmol/g.

The intermediate product (40.7 g) and potassium tert-butoxide (1 .3 g) were placed into a 2 I autoclave. After nitrogen neutralization the pressure was increased to 2 bar and the mixture was homogenized at 130 °C for 1 h. Then, a mixture of ethylene oxide (552 g) and propylene oxide (753 g) at 130 °C over a period of 10 h, reaching a maximum pressure of 7 bar. To complete the reaction, the mixture was allowed to post-react for 12 h at 130 °C. Then, the temperature was decreased to 80 °C and volatile

compounds were removed in vacuo at 80 °C. Suppressor 2 was obtained as a yellow high viscous liquid (1348 g) having an amine number of 0.33 mmol/g.

Example 3: Synthesis of suppressor 3

1 ,4-Bis(3-aminopropyl)piperazine (500 g) and water (25 g) were placed into a 3.5 L autoclave at 80 °C. After nitrogen neutralization a pressure of 1 bar was adjusted with nitrogen and the vessel heated to 1 10 °C. Then, propylene oxide (580 g) was added in portions at 1 10 °C over a period of 7 h 30 min. To complete the reaction, the mixture was allowed to post-react for 6 h. Then, the reaction mixture was cooled to 80 °C and stripped with nitrogen. Water and volatile organic compounds were removed in vacuo at 100°C. The intermediate product was obtained as a dark orange oil having an amine number of 9.25 mmol/g.

The intermediate product (61 .4 g) and potassium tert-butoxide (1 .5 g) were placed into a 2 I autoclave at 80 °C. After nitrogen neutralization, the pressure was increased to 2 bar and the mixture was homogenized at 130 °C for 1 h. Then, propylene oxide (671 g) was added at 130 °C over a period of 8 h, followed by a post-reaction for 6 h at the same temperature. Subsequently, ethylene oxide (534 g) was added at 130 °C over a period of 4 h. To complete the reaction, the mixture was allowed to post-react for 5 h at 130 °C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuo at 80 °C. Suppressor 3 was obtained as dark orange oil (931 g).

Example 4: Synthesis of suppressor 4

1 -Amino-4-methylpiperazine (123 g) was placed into a 3.5 L autoclave. After nitrogen neutralization the vessel was purged with nitrogen to obtain a pressure of 1.5 bar and heated to 1 10 °C, Then, propylene oxide (124 g) was added over a period of 3 h. To complete the reaction, the mixture was allowed to post-react for 8 h. Then, the reaction mixture was cooled to 70 °C and stripped with nitrogen. The intermediate product was obtained as a brownish oil (825 g) having an amine number of 8.53 mmol/g. The intermediate product (101.3 g) and potassium tert-butoxide (1.37 g) were placed into a 3.5 I autoclave. After nitrogen neutralization the pressure was increased to 1.5 bar and the mixture was homogenized at 130 °C for 1 h. Then, propylene oxide (722 g) was added at 130 °C over a period of 8 h, followed by a post-reaction for 10 h at the same temperature. Subsequently, ethylene oxide (308 g) was added at 130 °C over a period of 6 h. To complete the reaction, the mixture was allowed to post-react for 8 h at 130 °C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuo at 80 °C. Suppressor 4 was obtained as brown oil (1 145 g) having an amine number of 0.93 mmol/g.

Example 5: Synthesis of suppressor 5

N-Methylpiperazine (503 g) was placed into a 3.5 L autoclave. After nitrogen neutralization the vessel was purged with nitrogen to obtain a pressure of 1.5 bar and heated to 1 10 °C, Then, propylene oxide (292 g) was added over a period of 5 h. To complete the reaction, the mixture was allowed to post-react for 8 h. Then, the reaction mixture was cooled to 70 °C and stripped with nitrogen. The intermediate product was obtained as yellow oil (769 g) having an amine number of 12.6 mmol/g. The inter- mediate product (74 g) and potassium tert-butoxide (2.3 g) were placed into a 3.5 I autoclave. After nitrogen neutralization the pressure was increased to 1.5 bar and the mixture was homogenized at 130 °C for 1 h. Then, propylene oxide (817 g) was added at 130 °C over a period of 8 h, followed by a post-reaction for 12 h at the same temperature. Subsequently, ethylene oxide (639 g) was added at 130 °C over a period of 5 h. To complete the reaction, the mixture was allowed to post-react for 10 h at

130°C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuo at 80 °C. Suppressor 5 was obtained as brown oil (1 145 g) having an amine number of 0.64 mmol/g.

Example 6: Synthesis of suppressor 6 The intermediate product (1 12.9 g) from example 2 and potassium tert-butoxide (2,5 g) were placed into a 5 I autoclave. After nitrogen neutralization the pressure was increased to 1 ,5 bar and the mixture was homogenized at 130 °C for 1 h. Then, a mixture of ethylene oxide (884 g) and butylene oxide (648 g) was added at 130 °C over a period of 12 h. To complete the reaction, the mixture was allowed to post-react for 12 h at 130 °C. Then, the temperature was decreased to 80 °C and volatile

compounds were removed in vacuo at 80 °C. Suppressor 6 was obtained as a light brown high viscous liquid (1640 g) having an amine number of 0.70 mmol/g. Example 7: Synthesis of suppressor 7

The intermediate product (157 g) from example 2 and potassium tert-butoxide (1 .5 g) were placed into a 3.5 I autoclave. After nitrogen neutralization the pressure was adjusted to 1 bar and the mixture was homogenized at 130 °C for 1 h. Then, a mixture of ethylene oxide (215 g) and propylene oxide (674 g) was added at 130 °C over a period of 16 h, reaching a maximum pressure of 12 bar. To complete the reaction, the mixture was allowed to post-react for 10 h at 130 °C. Then, the temperature was decreased to 80 °C and volatile compounds were removed in vacuo at 80 °C.

Suppressor 7 was obtained as a yellowish high viscous liquid (1060 g) having an amine number of 1.57 mmol/g.

Example 8: Synthesis of suppressor 8

Piperazine (393.6 g) was placed into a 3.5 I autoclave. After nitrogen neutralization the vessel was heated up to 120 °C and propylene oxide (530 g) was added over a period of 6 h reaching a maximum pressure of 4 bar. To complete the reaction, the mixture was allowed to post-react for 6 h at 120 °C. Then, the reaction mixture was cooled to 80 °C and stripped with nitrogen. The intermediate product was obtained (925 g) having an amine number of 9.6 mmol/g.

Subsequently the intermediate product (72.8 g) and potassium tert-butoxide (7.5 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 propylene oxide (1317 g) was added at 130 °C over a period of 9 h, reaching a maximum pressure of 8 bar. Afterwards ethylene oxid (130 g) was added at 130 °C over a period of 18 h, reaching a maximum pressure of 8 bar. To complete the reaction, the mixture was allowed to post-react for 6 h at 130 °C. Then, the

temperature was decreased to 80 °C and volatile compounds were removed in vacuo at 80 °C.

Suppressor 8 was obtained as a yellowish high viscous liquid (2420 g) having an amine number of 0.32 mmol/g. Plating experiments

Example 9: Electroplating with Suppressor 1 A plating bath was prepared by combining Dl water, 40 g/l copper as copper sulfate, 10 g/l sulfuric acid, 0.050 g/l chloride ion as HCI, 0.028 g/l of SPS and 3.00 ml/l of a 4.5 wt % solution in Dl water of suppressor 1 as prepared in example 1 .

A copper layer was electroplated onto a wafer substrate with features provided with a copper seed layer by contacting the wafer substrate with the above described plating bath at 25 degrees C applying a direct current of -3 mA/cm² for 3.4 s or 10 s respectively. The thus electroplated copper layer was investigated by scanning electron micrograph (SEM) inspection. The results are shown in figs. 1 a and 1 b which provide SEM images of the copper filled trenches. The neighboring trenches are almost equally filled without exhibiting voids or seams in the fully filled trenches after 10 s plating as shown in fig. 1 b. The SEM image after 3.4 s plating, depicted in fig. 1 a, exhibits bottom-up filling of the trenches with almost no copper deposition on the sidewall of the trenches.

Example 10: Electroplating with Suppressor 2

A plating bath was prepared by combining Dl water, 40 g/l copper as copper sulfate, 10 g/l sulfuric acid, 0.050 g/l chloride ion as HCI, 0.028 g/l of SPS and 5.00 ml/l of a 5.0 wt % solution in Dl water of suppressor 2 as prepared in example 2.

A copper layer was electroplated onto a wafer substrate with features provided with a copper seed layer by contacting the wafer substrate with the above described plating bath at 25 degrees C applying a direct current of -3 mA/cm² for 3.4 s or 7 s

respectively. The thus electroplated copper layer was investigated by SEM inspection.

The results are shown in figs. 2a and 2b. Fig. 2a provides the SEM image of partly filled trenches exhibiting the bottom-up filling with pronounced suppression of Cu deposition at the feature opening. The neighboring trenches are almost equally filled without exhibiting voids or seams as depicted in fig. 2b showing fully filled trenches. The strong suppressing effect on the trench sidewalls can be clearly seen since the small feature openings are still obvious and did not close while partially filling the trenches. During the 3.4 s plating there was no significant amount of copper deposited at the trench sidewalls close to the opening thus avoiding formation of pinch-off voids. Example 1 1 : Electroplating with Suppressor 3

A plating bath was prepared by combining Dl water, 40 g/l copper as copper sulfate, 10 g/l sulfuric acid, 0.050 g/l chloride ion as HCI, 0.028 g/l of SPS, and 3.00 ml/l of a 4.6 wt % solution in Dl water of suppressor 3 as prepared in example 3.

A copper layer was electroplated onto a wafer substrate with features provided with a copper seed layer by contacting the wafer substrate with the above described plating bath at 25 degrees C applying a direct current of -3 mA/cm² for 3.4 s or 10 s

Figs. 3a and 3b show the SEM images of the resulting electroplated copper layer. Both images of partly filled trenches (fig. 3a) and fully filled trenches (fig. 3b) are free of defects like voids or seams.

Example 12: Electroplating with Suppressor 4

A plating bath was prepared by combining Dl water, 40 g/l copper as copper sulfate, 10 g/l sulfuric acid, 0.050 g/l chloride ion as HCI, 0.028 g/l of SPS, and 1 1.00 ml/l of a 1 .2 wt % solution in Dl water of suppressor 4 as prepared in example 4.

A copper layer was electroplated onto a wafer substrate with features provided with a copper seed layer by contacting the wafer substrate with the above described plating bath at 25 degrees C applying a direct current of -3 mA/cm² for 3.4 s or 27 s

The results are shown in figs. 4a and 4b which exhibit a SEM image of the partly filled trenches after 3.4 s (fig. 4a) as well as of the fully filled trenches after 27 s (fig. 4b). Fig. 4a exhibits a strong suppression of the copper growth at the sidewalls of the trenches. Fig. 4b shows fully filled trenches without exhibiting voids or seams.

Example 13: Electroplating with Suppressor 5 A plating bath was prepared by combining Dl water, 40 g/l copper as copper sulfate, 10 g/l sulfuric acid, 0.050 g/l chloride ion as HCI, 0.028 g/l of SPS, and 2.50 ml/l of a 4.2 wt % solution in Dl water of suppressor 5 as prepared in example 5.

A copper layer was electroplated onto a wafer substrate with features provided with a copper seed layer by contacting the wafer substrate with the above described plating bath at 25 degrees C applying a direct current of -3 mA/cm² for 3.4 s or 27 s . The thus electroplated copper layer was investigated by SEM inspection. The resulting SEM images are shown in figs. 5a and 5b. The partly filled trenches after 3.4 s, shown in fig. 5a, exhibit a strong suppression of the copper growth on the sidewalls of the trenches. All feature openings are still open. After 27 s deposition time, shown in fig. 5b, the trenches are fully filled with copper without exhibiting any defects like voids or seams.

Example 14: Electroplating with Suppressor 6 A plating bath was prepared by combining Dl water, 40 g/l copper as copper sulfate, 10 g/l sulfuric acid, 0.050 g/l chloride ion as HCI, 0.028 g/l of SPS, and 2.50 ml/l of a 4.4 wt % solution in Dl water of suppressor 6 as prepared in example 6.

A copper layer was electroplated onto a wafer substrate with features provided with a copper seed layer by contacting the wafer substrate with the above described plating bath at 25 degrees C applying a direct current of -3 mA/cm² for 3.4 s or 10 s . The thus electroplated copper layer was investigated by SEM inspection.

The resulting SEM images are shown in figs. 6a and 6b. The partly filled trenches after 3.4 s, shown in fig. 6a, exhibit a strong suppression of the copper growth on the sidewalls of the trenches. All feature openings are still open. After 10 s deposition time, shown in fig. 6b, the trenches are fully filled with copper without exhibiting any defects like voids or seams. Example 15: Electroplating with Suppressor 7

A plating bath was prepared by combining Dl water, 40 g/l copper as copper sulfate, 10 g/l sulfuric acid, 0.050 g/l chloride ion as HCI, 0.028 g/l of SPS, and 2.00 ml/l of a 5.0 wt % solution in Dl water of suppressor 7 as prepared in example 7.

A copper layer was electroplated onto a wafer substrate with features provided with a copper seed layer by contacting the wafer substrate with the above described plating bath at 25 degrees C applying a direct current of -3 mA/cm² for 3.4 s or 27 s . The thus electroplated copper layer was investigated by SEM inspection.

The resulting SEM images are shown in figs. 7a and 7b. The partly filled trenches after 3.4 s, shown in fig. 7a, exhibit a strong suppression of the copper growth on the sidewalls of the trenches. All feature openings are still open. After 27 s deposition time, shown in fig. 7b, the trenches are fully filled with copper exhibiting few small but still tolerable number of defects. Example 16: Electroplating with Suppressor 8

A plating bath was prepared by combining Dl water, 40 g/l copper as copper sulfate, 10 g/l sulfuric acid, 0.050 g/l chloride ion as HCI, 0.028 g/l of SPS, and 3.00 ml/l of a 4.5 wt % solution in Dl water of suppressor 8 as prepared in example 8.

The resulting SEM images are shown in figs. 8a and 8b. The partly filled trenches after 3.4 s, shown in fig. 8a, exhibit a strong suppression of the copper growth on the sidewalls of the trenches. All feature openings are still open. After 10 s deposition time, shown in fig. 8b, the trenches are fully filled without exhibiting any defects like voids or seams.

Claims

1 . A composition comprising metal ions and at least one compound of formula I

X

R- -X²- \ N- -X- (i)

x⁴

wherein

X¹ and X² are independently selected from a chemical bond and straight chain or branched C1-C18 alkanediyl, which may optionally be interrupted by O, S and NR¹⁰, X³ and X⁴ are independently selected from straight chain or branched C1-C18

R³ is selected from R¹, NR¹R² and C1-C20 alkyl, which may be substituted or unsubstituted, and which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl,

Z is selected from NR¹R² and, only if X¹ is a chemical bond, also from

R¹,

R¹ and R² are independently selected from a copolymer of ethylene oxide and at least one further C3 to C12 alkylene oxide or styrene oxide,

R¹⁰ is selected from (a) H, (b) C1-C20 alkyl, which may optionally be

substituted by hydroxyl, alkoxy or alkoxycarbonyl, and (c) C1-C20 alkenyl, which may optionally be substituted by hydroxyl, alkoxy or alkoxycarbonyl.

2. The composition according to claim 1 , wherein Z is NR¹R².

3. The composition according to claim 2, wherein

X¹ and X² are independently selected from a chemical bond, X³ and X⁴ are independently selected from straight chain or branched Ci-Cs

alkanediyl, which may optionally be interrupted by O and NR¹⁰, R¹, R², R³ are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide,

R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

The composition according to claim 2, wherein

X¹ and X² are independently selected from straight chain or branched Ci-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰,

X³ and X⁴ are independently selected from straight chain Ci-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰,

R¹ and R² are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide,

R³ is selected from NR¹R²,

R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

The composition according to claim 2, wherein

X¹ is selected from straight chain or branched Ci-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰,

X² is selected from a chemical bond,

X³ and X⁴ are independently selected from straight chain C-i-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰,

R¹, R², R³ are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide,

R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

6. The composition according to claim 2, wherein

X¹ is selected from straight chain or branched C-i-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰,

X² is selected from a chemical bond, X³ and X⁴ are independently selected from straight chain Ci-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰,

R¹, R² are independently selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide,

R³ is selected from Ci-Cs alkyl, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl, R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

7. The composition according to claim 2, wherein X¹ and X² are selected from a chemical bond,

X³ and X⁴ are independently selected from straight chain or branched Ci-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰,

R³ is selected from C-i-Cs alkyl, and

R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

8. The composition according to claim 1 , wherein X¹ is a chemical bond and Z is R¹.

9. The composition according to claim 8, wherein X² is selected from a chemical bond,

X³ and X⁴ are independently selected from straight chain or branched d-Cs alkanediyl, which may optionally be interrupted by O and NR¹⁰, R¹ is selected from a copolymer of ethylene oxide and at least one

further C3 to C6 alkylene oxide,

R³ is selected from C-i-Cs alkyl, and R¹⁰ is selected from H and unsubstituted C1-C20 alkyl.

10. The composition according to claim 8, wherein X² is a chemical bond,

X³ and X⁴ are independently selected from straight chain or branched Ci-Cs

alkanediyl, which may optionally be interrupted by O and NR¹⁰, R¹ is selected from a copolymer of ethylene oxide and at least one further C3 to C6 alkylene oxide,

R³ is R¹, and

R10 is selected from H and unsubstituted C1-C20 alkyl.

1 1 . The composition according to anyone of the preceding claims, wherein X¹ and X² are independently selected from straight chain or branched C2 to Cs alkanediyl, preferably C2 to C₄ alkanediyl.

12. The composition according to anyone of the preceding claims, wherein the

further C3 to C12 alkylene oxide is propylene oxide, 1 ,2-butylene oxide or a combination thereof.

13. The composition according to anyone of the preceding claims, wherein the

content of ethylene oxide in R¹, if applicable, R² and R³ is from 25 to 70 % by weight, preferably from 30 to 65 % by weight. 14. The composition according to anyone of the preceding claims, wherein the metal comprises copper, preferably consists of copper.

15. The composition according to anyone of the preceding claims, further comprising one or more accelerating agents, one or more leveling agents, or a combination thereof.

16. Use of a metal plating bath comprising a composition according to anyone of claims 1 to 15 for depositing copper on substrates comprising features having an aperture size of 30 nanometers or less.

17. A process for depositing a metal layer on a substrate comprising nanometer- sized features by

a) contacting a composition according to any one of claims 1 to 15 with the substrate, and

b) applying a current density to the substrate for a time sufficient to deposit a metal layer onto the substrate, wherein the substrate comprises nanometer sized features and the deposition is performed to fill the micrometer or nanometer sized features.