Compositions and methods for making nickel interconnects

Abstract

A nickel electrodeposition composition for via filling or barrier nickel interconnect fabrication, the nickel electrodeposition composition comprising: (a) a nickel ion source; (b) one or more polarizing additives; and (c) one or more depolarizing additives. The nickel electrodeposition composition may contain various additives, including suitable acids, surfactants, buffers, and / or stress modifiers, to produce bottom-up filling of vias and trenches.

Description

Technical Field

[0001] The present invention generally relates to compositions and methods for metal electrodeposition, particularly nickel and nickel alloy electrodeposition, which can be used for metallization of vias and trenches in microelectronic devices, as well as for nickel-rich interconnect applications such as nickel pillars, nickel bumps, UBM barriers, and RDL metallization applications. Background Art

[0002] Integrated circuits are fabricated from a semiconductor substrate with multiple devices, such as transistors, capacitors, and resistors, interconnected to form a circuit. The interconnects typically consist of metal traces that connect these devices on the substrate. Similarly, multilayer printed circuit boards are made of layers of conductive metal sandwiched between dielectric and semiconductor layers that are interconnected through vias or through-holes.

[0003] Metal-filled vias allow three-dimensional (3D) stacking to connect various conductor metal layers. Stacking provides shorter signal paths and faster, more efficient interconnects.

[0004] With 3D or vertical integration, chips are stacked and connected together by vertical interconnects. The resulting stack includes several layers or stacks of active components or chips; it forms a three-dimensional integrated circuit (3DIC).

[0005] Some of the advantages of 3D integration include:

[0006] (1) Improved performance, including reductions in propagation time and dissipated power, increases in the operating speed of the system associated with faster communication between functional blocks, increases in bandwidth per functional block, and greater immunity to noise;

[0007] (2) reduced costs, better manufacturing yields (due in part to the generation of electronic chips best suited for each functional block), and improved reliability resulting from increased integration density; and

[0008] (3) Producing highly integrated systems by stacking heterogeneous technologies (also called co-integration), i.e., involving various materials and / or various functional components.

[0009] After the chips are stacked, for example by bonding, they can be individually connected to the pins of the package using connecting wires.However, high-density interconnection of chips can only be achieved by using through-holes.

[0010] In some 3D IC fabrication processes, two wafers are formed, each containing integrated circuits. The wafers are then bonded together with the devices aligned. Deep vias are then formed to interconnect the devices on the first and second wafers.

[0011] Through-silicon vias (TSVs), also known as through-substrate vias (TSVs) or through-wafer vias (TWVs), are increasingly being used to implement 3D ICs. Typically, a bottom wafer is bonded to a top wafer. TSVs are commonly used in 3D ICs and stacked dies to provide electrical connections and / or aid in heat dissipation. TSVs are a key component of three-dimensional integrated circuits and can be found in RF devices, MEMS, CMOS image sensors, flash memory, DRAM, SRAM, 3D-NAND memory, analog devices, and logic devices.

[0012] The quality of the interconnections of these devices is critical to the performance and reliability of the fabricated integrated circuits. Furthermore, the fabrication of interconnects for microelectronic devices relies on completely filling vias and trenches with electrodeposited metal.

[0013] One of the most commonly used metals for interconnects is electrodeposited copper. However, copper as the primary interconnect conductor metal can present many challenges. One of the most significant challenges is interconnect reliability. While copper is an excellent conductor, it is easily oxidized in ambient air. To protect copper from oxidation and to maintain its solderability, it is typically plated with layers or stacks of metals, including, for example, nickel, cobalt, silver, tin, palladium, and gold.

[0014] Therefore, instead of protecting the top surface of the copper, the reliability of these interconnects can be significantly improved if the entire interconnect is fabricated from a metal other than copper that is less susceptible to reliability failures.

[0015] In addition, in the process of stacking the layers of the device, these layers experience multiple high-temperature thermal excursions during the bonding process. The coefficients of thermal expansion (CTE) of silicon and copper are very different. Silicon hardly expands when exposed to the high temperatures used for bonding, while copper expands significantly with each thermal cycle. Each subsequent Moore's Law node produces a combination of reducing copper thickness and increasing the number of stacked layers, which leads to an increasing number of thermal exposures. When exposed to multiple thermal excursion cycles, copper, as a ductile and flexible metal with a high CTE, can experience cracking. The cracking of copper wires is a high reliability failure risk. Therefore, it is necessary to replace copper with a more rigid metal with higher tensile strength and yield strength, which does not experience so much movement relative to silicon during the layer bonding thermal cycle due to its higher thermal stability and higher rigidity, and is therefore less prone to cracking.

[0016] Copper also has a tendency to form intermetallic compounds with tin at a fairly high rate. Tin is the main component of solder commonly used to attach various electronic components. Copper-tin intermetallic compounds can further impair interconnect reliability.

[0017] Copper via electrodeposition is widely used in a variety of applications, such as damascene processes, RDLs, TSVs, and high-density interconnect (HDI) and sequential microvia build-up (SBU) printed circuit board manufacturing processes. A similar filling process is used for patterned through-photoresist copper pillars in wafer-level packaging.

[0018] Copper via fill electrodeposition is described in US Patent 7,670,950 to Richardson et al., the subject matter of which is incorporated herein by reference in its entirety.

[0019] Cobalt has also been used for electroplating into recessed features, for example, in US Patent 9,777,386 to Doubina et al., the subject matter of which is incorporated herein by reference in its entirety.

[0020] Nickel is a potential alternative to copper; however, boric acid has historically been an essential component of nickel electrodeposition chemistry. Boric acid functions as a buffer for the cathode diffusion layer. During nickel electrodeposition, a secondary reaction, hydrogen evolution, occurs at the cathode due to proton reduction. Hydrogen gas is generated and released at the cathode, simultaneously depleting the diffusion layer of protons and increasing its pH. Boric acid acts as a buffer to maintain a relatively stable pH.

[0021] However, according to the European Commission, high doses of boric acid have shown significant developmental toxicity and teratogenicity in rabbit, rat, and mouse fetuses, as well as cardiovascular defects, skeletal variations, and mild renal impairment. The European Commission has revised the classification of boric acid to reproductive toxicity Category 2, R60 (may impair fertility) and R61 (may cause harm to the unborn child). Therefore, alternatives to nickel electrodeposition chemistries that utilize boric acid are needed.

[0022] In addition, because the quality of the interconnects is crucial to the performance and reliability of the manufactured integrated circuits, it is necessary to modify the internal stresses in the applied coatings or deposited pathways, which can cause the applied coatings to fracture. Internal stresses in the applied coatings can lead to blistering, peeling, and reduced fatigue strength. Internal stresses can be tensile in nature, causing the applied coatings to shrink, or compressive in nature, causing the applied coatings to expand. Micro- and macro-cracks within the applied deposits expose the integrated circuits to corrosion and ultimately reduce the performance and reliability of the integrated circuits. Therefore, methods and additives for modifying the internal stresses in the applied coatings are needed. Sometimes, a metal layer has an internal stress value that can be compensated by applying another metal layer with an opposite stress value on top of it, thereby allowing the stress of the entire stack to be kept neutral.

[0023] Therefore, it is necessary to provide a solution to the above problems. Summary of the Invention

[0024] The present invention is directed to providing electrodeposition compositions and methods for via fill metallization and interconnect fabrication comprising metals other than copper. In some embodiments, the metal in the electrodeposition composition may be nickel. The electrodeposition composition may also advantageously comprise one or more polarizers / suppressors and one or more accelerators / depolarizers.

[0025] It is another object of the present invention to provide electrodeposition compositions and methods for via fill metallization that do not include boric acid.

[0026] It is another object of the present invention to provide an internal stress modifier in electrodeposition compositions and methods for via fill metallization.

[0027] Other objects and features will be in part apparent and in part pointed out hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Graphs of constant current chronopotentiometry according to Examples 1 to 4 are shown. DETAILED DESCRIPTION

[0029] The present invention generally relates to nickel electrodeposition compositions and methods for via fill metallization in microelectronic devices. As described herein, in some embodiments, the present invention relates to methods for filling vias and trenches in microelectronic devices with metals other than copper to improve reliability.

[0030] As used herein, "a," "an," and "the" refer to both the singular and the plural, unless the context clearly dictates otherwise.

[0031] As used herein, the term "about" refers to a measurable value, such as a parameter, amount, duration, etc., and is intended to include variations of + / -15% or less, preferably + / -10% or less, more preferably + / -5% or less, even more preferably + / -1% or less, and still more preferably + / -0.1% or less relative to the specifically recited value, as long as such variations are suitable for performing the inventions described herein. In addition, it should be understood that the value to which the modifier "about" refers is itself specifically disclosed herein.

[0032] As used herein, the terms “include and / or include” specify the presence of stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0033] As used herein, the term "acid" refers to any suitable acid, typically a Bronsted-Lowry acid, including but not limited to inorganic acids, carboxylic acids, alcohols, thiols, water, and the like.

[0034] "Alkyl" as used herein alone or as part of another group refers to a straight chain, branched or cyclic, saturated or unsaturated hydrocarbon containing from 1 or 2 to 10 or 20 or more carbon atoms. Representative examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 3-methylhexyl, 2,2-dimethylpentyl, 2,3-dimethylpentyl, n-heptyl, n-octyl, n-nonyl, n-decyl, and the like. Unless otherwise indicated, the term "alkyl" is intended to include substituted and unsubstituted alkyl groups, and these groups can be selected from halo (e.g., haloalkyl), alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aryl, arylalkyl, heterocyclyl, heterocycloalkyl, hydroxy, alkoxy (thereby giving rise to polyalkoxy groups such as polyethylene glycol), alkenyloxy, alkynyloxy, haloalkoxy, cycloalkoxy, cycloalkylalkoxy, aryloxy, aralkyloxy, heterocyclyloxy, heterocycloalkyloxy, mercapto, alkyl-S(O) m , haloalkyl-S(O) m , alkenyl-S(O) m , alkynyl-S(O)m, cycloalkyl-S(O) m , cycloalkylalkyl-S(O) m , aryl-S(O) m , arylalkyl-S(O) m 、Heterocycloalkyl-S(O)m、Heterocycloalkyl-S(O) m , amino, carboxyl, alkylamino, alkenylamino, alkynylamino, haloalkylamino, cycloalkylamino, cycloalkylalkylamino, arylamino, arylalkylamino, heterocyclic amino, heterocyclic alkylamino, disubstituted amino, acylamino, acyloxy, ester, amide, sulfonamide, urea, alkoxyacylamino, aminoacyloxy, nitro or cyano, wherein m=0, 1, 2 or 3.

[0035] Alkyl groups may be saturated or unsaturated, and thus when an alkyl substituent contains one or more unsaturated bonds (e.g., one or two double or triple bonds), the term "alkyl" as used herein includes alkenyl and alkynyl groups. Alkyl groups may optionally contain one or more heteroatoms (e.g., one, two, or three or more heteroatoms independently selected from O, S, and NR', where R' is any suitable substituent, such as described immediately above for alkyl substituents) to form straight-chain heteroalkyl or heterocyclic groups, as described in detail below.

[0036] As used herein, "alkenyl" refers to an alkyl group as described above that contains at least one double bond between two carbon atoms. Additionally, an alkenyl group substituted with a hydroxyl group or a thiol group may be referred to as an enol or alkenethiol, respectively. Exemplary substituents include vinyl and allyl.

[0037] As used herein, "alkynyl" refers to an alkyl group as described above containing at least one triple bond between two carbon atoms. Additionally, an alkynyl group substituted with a hydroxyl group or a thiol group may be referred to as an alkynol or an alkynylthiol, respectively.

[0038] As used herein, "heterocyclic group" or "heterocyclyl" refers to an aliphatic (e.g., a fully or partially saturated heterocycle) or aromatic (e.g., a heteroaryl) monocyclic or bicyclic ring system. Monocyclic ring systems are exemplified by any 5- or 6-membered ring containing 1, 2, 3, or 4 heteroatoms independently selected from oxygen, nitrogen, and sulfur. The 5-membered ring has 0-2 double bonds, and the 6-membered ring has 0-3 double bonds. Representative examples of monocyclic ring systems include, but are not limited to, azetidine, azepine, aziridine, diazepine, 1,3-dioxolane, dioxane, dithiane, furan, imidazole, imidazoline, imidazolidine, isothiazole, isothiazolidine, isoxazole, isoxazoline, isoxazolidine, morpholine, oxadiazole, oxadiazolin, oxadiazolidine, oxazole, oxazoline, oxazolidine, piperazine, piperidine, pyran, pyrazine, pyrazole, pyrazoline, pyrazolidine, pyridine, pyrimidine, pyridazine, pyrrole, pyrroline, pyrrolidine, tetrahydrofuran, tetrahydrothiophene, tetrazine, tetrazole, thiadiazole, thiadiazoline, thiadiazolidine, thiazole, thiazoline, thiazolidine, thiophene, thiomorpholine, thiomorpholine sulfone, thiopyran, triazine, triazole, trithiane, and the like. The bicyclic ring system is composed of any of the above monocyclic ring systems fused to an aryl group as defined herein, a cycloalkyl group as defined herein, or another monocyclic ring system as defined herein. Representative examples of bicyclic ring systems include, but are not limited to, for example, benzimidazole, benzothiazole, benzothiadiazole, benzothiophene, benzoxadiazole, benzoxazole, benzofuran, benzopyran, benzothiopyran, benzodioxin, 1,3-benzodioxole, cinnoline, indazole, indole, dihydroindole, indolizine, naphthyridine, isobenzofuran, isobenzothiophene, isoindole, isodihydroindole, isoquinoline, phthalazine, purine, pyranopyridine, quinoline, quinolizine, quinoxaline, quinazoline, tetrahydroisoquinoline, tetrahydroquinoline, thiopyranopyridine, etc. These rings include quaternized derivatives thereof and may be optionally substituted with groups selected from the group consisting of halo, alkyl, haloalkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, aryl, arylalkyl, heterocyclyl, heterocycloalkyl, hydroxy, alkoxy, alkenyloxy, alkynyloxy, haloalkoxy, cycloalkoxy, cycloalkylalkoxy, aryloxy, arylalkoxy, heterocyclyloxy, heterocyclylalkoxy, mercapto, alkyl-S(O) m , haloalkyl-S(O) m , alkenyl-S(0)m, alkynyl-S(0) m , cycloalkyl-S(O) m , cycloalkylalkyl-S(O) m , aryl-S(O) m , arylalkyl-S(O)m, heterocyclic-S(O)m 、Heterocycloalkyl-S(O) m , amino, alkylamino, alkenylamino, alkynylamino, haloalkylamino, cycloalkylamino, cycloalkylalkylamino, arylamino, arylalkylamino, heterocyclic amino, heterocyclic alkylamino, disubstituted amino, acylamino, acyloxy, ester, amide, sulfonamide, urea, alkoxyacylamino, aminoacyloxy, nitro or cyano, wherein m=0, 1, 2 or 3.

[0039] "Aryl," as used herein alone or as part of another group, refers to a monocyclic carbocyclic ring system or a bicyclic carbocyclic fused ring system having one or more aromatic rings. Representative examples of aryl groups include azulenyl, indanyl, indenyl, naphthyl, phenyl, tetrahydronaphthyl, and the like. Unless otherwise indicated, the term "aryl" is intended to include both substituted and unsubstituted aryl groups, and these groups may be substituted with the same groups as described above in conjunction with alkyl groups.

[0040] "Alkoxy" as used herein alone or as part of another group refers to an alkyl group, as defined herein, attached to the parent molecular moiety through an oxy group -O- (and thus includes substituted forms such as polyalkoxy). Representative examples of alkoxy include, but are not limited to, methoxy, ethoxy, propoxy, 2-propoxy, butoxy, tert-butoxy, pentoxy, hexoxy, and the like.

[0041] As used herein, "halo" refers to any suitable halogen, including -F, -CI, -Br, and -I.

[0042] As used herein, the term "molecular weight" is the average mass of a compound's molecules compared to one-twelfth the mass of carbon 12 and is calculated as the sum of the atomic weights of the constituent atoms.

[0043] As used herein, the term "zwitterion" is a molecule having two or more functional groups, wherein at least one functional group has a positive charge, one functional group has a negative charge, and the net charge of the entire molecule is zero.

[0044] As used herein, the term "betaine" is a specific type of zwitterion and is any neutral compound having a positively charged cationic functional group without a hydrogen atom and a negatively charged anionic functional group, wherein the anionic group is not immediately adjacent to the cationic group. Exemplary cationic groups include, but are not limited to, primary ammonium to quaternary ammonium and phosphonium cations. Exemplary anionic groups include, but are not limited to, carboxylate, sulfonate, and sulfate groups.

[0045] In one aspect, the present invention relates to providing an electrodeposition composition and method for path filling metallization comprising a metal other than copper. In some embodiments, the metal for filling the path and the groove can be selected from Group VIIIB of the periodic table, or more specifically from an iron metal. Nickel and cobalt are preferred metals, with nickel being most preferred. Nickel-cobalt alloys can also be used. Exemplary nickel alloys include NiCo, NiW, NiFe, NiMo, CoRe, NiCoW, and NiCoFe. Exemplary cobalt alloys include CoW, CoFe, NiCoW, and NiCoFe. Therefore, the electrodeposition composition can contain a combination of independent nickel and / or cobalt ions, or nickel and / or cobalt ions and one or more alloying metals.

[0046] The preferred method for via fill metallization may be electrodeposition. In some embodiments, the metal in the electrodeposition composition may be nickel. The electrodeposition composition may also advantageously contain a polarizing agent (suppressor) and a depolarizing agent (accelerator).

[0047]

[0014] In some embodiments, the present invention generally relates to nickel electrodeposition compositions and methods of using the nickel electrodeposition compositions to metallize vias and trenches in the fabrication of microelectronic devices.

[0048] More specifically, in some embodiments, the present invention generally relates to nickel electrodeposition compositions comprising a nickel ion source and at least one of a polarizing and depolarizing additive. As described above, the nickel electrodeposition composition may also contain one or more alloying metal ion sources.

[0049] In some preferred embodiments, the electrodeposition composition comprises:

[0050] a) nickel ion source;

[0051] b) one or more polarizing additives

[0052] c) one or more depolarizing additives;

[0053] d) at least one acid; and

[0054] e) at least one surfactant

[0055] In some preferred embodiments, the electrodeposition composition comprises:

[0056] a) nickel ion source;

[0057] b) one or more polarizing additives

[0058] c) one or more depolarizing additives;

[0059] d) at least one acid;

[0060] e) at least one surfactant; and

[0061] f) at least one buffer

[0062] In some preferred embodiments, the electrodeposition composition comprises:

[0063] a) nickel ion source;

[0064] b) one or more polarizing additives

[0065] c) one or more depolarizing additives;

[0066] d) at least one acid;

[0067] e) at least one surfactant; and

[0068] f) at least one stress modifier

[0069] In some preferred embodiments, the electrodeposition composition comprises:

[0070] a) nickel ion source;

[0071] b) one or more polarizing additives

[0072] c) one or more depolarizing additives;

[0073] d) at least one acid;

[0074] e) at least one surfactant;

[0075] f) at least one buffer; and

[0076] g) at least one stress modifier

[0077] As described herein, the present invention generally relates to nickel electrodeposition compositions comprising a nickel ion source, optionally with alloying metal ions, additional surfactants, complexing agents, solvents, and buffers. Although specific labels may be provided for the components, one of ordinary skill in the art will understand and recognize that certain components may function simultaneously or alternately depending on the overall bath composition.

[0078] In some embodiments, exemplary nickel ion sources include nickel acetate, nickel carboxylates, nickel chloride, nickel bromide, nickel sulfate, nickel sulfamate, nickel fluoroborate, and nickel pyrophosphate.

[0079] In some embodiments, as described herein, the nickel electrodeposition composition comprises an acid or a salt thereof. Exemplary acid comprises oxalic acid, citric acid, sulfamic acid, acetic acid, salicylic acid, sulfosalicylic acid, succinic acid, phthalic acid, boric acid, tartaric acid and the salt of any of the foregoing. In some embodiments, the composition does not contain any boric acid, and the acid is selected to be not boric acid. Surprisingly, the present inventor has found that it is possible to prepare a nickel electrodeposition composition that can provide the bottom-up filling of path and groove without using boric acid.

[0080] In some embodiments, the electrolyte bath may include a surfactant. Exemplary surfactants may include anionic surfactants, cationic surfactants, and nonionic surfactants. In some embodiments, the electrolyte bath may include anionic surfactants, such as 08 (2-ethylhexyl sodium sulfate aqueous solution) or 4 (sodium tetradecyl sulfate aqueous solution), both available from Niacet Corporation. Other surfactants, including nonionic surfactants such as polyethylene glycol ethers, alcohol ethoxylates, alkylphenol ethoxylates, fatty acid ethoxylates, ethylene oxide-propylene oxide copolymers and glycol esters, nonylphenol, ethoxylated nonylphenol and nonoxynol ether, can also be used in the practice of the present invention. These surfactants reduce the surface tension of the electrolyte solution to allow the release of hydrogen by-products. In plating applications, these surfactants eliminate the pitting corrosion caused primarily by particulate matter or hydrogen bubbles while reducing the surface tension of the bath.

[0081] The nickel via filling process can be controlled by adding a balanced combination of polarizing (suppressor) and depolarizing (promoter) additives. Thus, in some embodiments, the present invention involves adding one or more polarizing agents in combination with one or more depolarizing agents to the electrolyte used for electrodeposition.

[0082] An electrochemical technique based on galvanostatic chronopotentiometry can be used to screen additives for potential use as polarizers or depolarizers in nickel electrodeposition. Unconstrained by theory of operation, the proposed mechanism driving metal via-fill deposition is based on differences in additive mass transfer and adsorption rates between the field and the via bottom. In this mechanism, high cathodic polarization due to higher rotation rates indicates the deposition rate on the field, while lower cathodic polarization at lower stirring rates indicates the deposition rate at the via bottom. A large difference between the field deposition rate and the via bottom deposition rate leads to complete via filling.

[0083] Polarizers are defined herein as organic molecules that cause a negative shift in the metal deposition potential.

[0084] Examples of suitable polar additives (inhibitors) include organic molecules such as those selected from heterocyclic betaines, alkynols, enols and alkyl alcohols. Any of the foregoing may be substituted, polysubstituted or unsubstituted.

[0085] In some embodiments, the inhibitor may be at least one of pyridinium sulfate, pyridinium sulfonate, pyridinium sulfamate, pyridinium carbamate, pyridinium halide, and pyridinium acetate. Exemplary inhibitors may include at least one of pyridinium methanesulfonate, pyridinium ethylsulfonate, pyridinium propylsulfonate, and pyridinium butylsulfonate.

[0086] In some embodiments, the at least one inhibitor can be an alkylphosphonium sulfate, an alkylphosphonium sulfonate, an alkylphosphonium aminosulfonate, an alkylphosphonium carbamate, an alkylphosphonium halide, an alkylphosphonium acetate, a phosphonium methanesulfonate, a phosphonium ethylsulfonate, a propylphosphonium sulfonate, or a butylphosphonium sulfonate.

[0087] In some embodiments, at least one inhibitor can be methylpyridinium carboxylate, ethylpyridinium carboxylate, propylpyridinium carboxylate, butylpyridinium carboxylate, methylammonium carboxylate, ethylammonium carboxylate, propylammonium carboxylate, butylammonium carboxylate, methylphosphonium carboxylate, ethylphosphonium carboxylate, propylphosphonium carboxylate, butylphosphonium carboxylate, methylpyridinium sulfate, ethylpyridinium sulfate, propylpyridinium sulfate, butylpyridinium sulfate, methylammonium sulfate, ethylammonium sulfate, propylammonium sulfate, butylammonium sulfate, methylphosphonium sulfate, ethylphosphonium sulfate, propylphosphonium sulfate, butylphosphonium sulfate, methylammonium sulfate, methyl phosphonium sulfamate, ethyl phosphonium sulfamate, propyl phosphonium sulfamate, butyl phosphonium sulfamate, methyl ammonium sulfamate, ethyl ammonium sulfamate, propyl ammonium sulfamate, butyl ammonium sulfamate, methyl phosphonium sulfamate, ethyl phosphonium sulfamate, propyl phosphonium sulfamate, butyl phosphonium sulfamate, methyl pyridinium acetate, ethyl pyridinium acetate, propyl pyridinium acetate, butyl pyridinium acetate, methyl ammonium acetate, ethyl ammonium acetate, propyl ammonium acetate, butyl phosphonium acetate, methyl phosphonium acetate, ethyl phosphonium acetate, propyl phosphonium acetate, butyl phosphonium acetate.

[0088] In some embodiments, at least one inhibitor can be an alkoxylated alcohol, an alkoxylated alkynol, an alkoxylated enol, an alkoxylated alkyl alcohol, a C1-C20 alkoxylated alkynol. C1-C20 alkoxylated enol. C1-C20 alkoxylated alkyl alcohol, alkyl glycol, methyl glycol, ethyl glycol, propyl glycol, butyl glycol, pentyl glycol, ethylene glycol, propylene glycol, butylene glycol, pentyl glycol, methoxylated alkyl alcohol, ethoxylated alkyl alcohol, propoxylated alkyl alcohol, butoxylated alkyl alcohol, methoxylated enol, ethoxylated enol, propoxylated enol, butoxylated enol, methoxylated alkynol, ethoxylated alkynol, propoxylated alkynol, butoxylated alkynol, methoxylated Acetylene alcohol, ethoxylated acetylene alcohol, propoxylated acetylene alcohol, butoxylated acetylene alcohol, methoxypropynyl alcohol, ethoxypropynyl alcohol, propoxypropynyl alcohol, butoxypropynyl alcohol, methoxylated propargyl alcohol, ethoxylated propargyl alcohol, propoxylated propargyl alcohol, butoxylated propargyl alcohol, methoxylated butynol, ethoxylated butynol, propoxylated butynol, butoxylated butynol, methoxylated pentynol, ethoxylated pentynol, propoxylated pentynol, butoxylated pentynol.

[0089] In some embodiments, at least one inhibitor can be a zwitterion. In some embodiments, at least one inhibitor can be a betaine. Betaines can be substituted or unsubstituted. Optional substituents can be hydroxyl, alkyl, alkynyl, alkenyl, and halide. In some embodiments, at least one inhibitor can be an alkyl betaine, a cyclic betaine, an aryl betaine, a heterocyclic betaine, and a hydroxylated betaine. In some embodiments, at least one inhibitor can be a vinyl betaine, a propargyl betaine, and a vinyl heterocyclic betaine.

[0090] Exemplary betaines include (carboxymethyl)trimethylammonium chloride, (formylmethyl)trimethylammonium chloride, 1,1'-[thiobis(mercaptothiophosphinyl)]bispyridinium, bis(inner salt), P4S10-pyridine complex, N-(3-sulfopropyl)-N-methacryloyloxyethyl-N,N-dimethylammonium betaine, (N,N-dimethylmyristylammonium) acetate, trigonelline hydrochloride, (lauryldimethylammonium) acetate, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, N-methylnorpapaverine, 3-(1-pyridyl)-1-propanesulfonate, N-(trimethylamine-boranecarbonyl)proline methyl ester, hydroxysulfopropylpyridinium betaine, sulfopropylvinylpyridinium betaine.

[0091] Depolarizers are defined herein as molecules that cause a positive shift in the nickel deposition potential. Examples of suitable depolarizing additives (accelerators) include, for example, organic sulfur compounds. More preferably, the depolarizing additive is selected from the group consisting of: sulfimides, sulfonates, and sulfates. Specific examples of depolarizing additives include, but are not limited to, sulfur-containing organic compounds, aromatic and aliphatic sulfonates, benzene, diphenyl, naphthalene, toluenesulfonamide, sulfonimides, such as benzenesulfonic acid, 1,3,6-naphthalenesulfonic acid sodium salt, p-toluenesulfonamide, o-phthalic acid sulfonimide, thiophene-2-sulfonic acid, benzenesulfinic acid, etc., which can be used alone or in combination.

[0092] The one or more polarizing additives and the one or more depolarizing additives are present in the composition in a ratio between about 100:1 and about 1:100, more preferably between about 100:1 and about 1:1. For example, in some embodiments, the ratio of accelerator to inhibitor may be in the range of 100:1 to 1:1 weight percent. In some embodiments, the ratio of accelerator to inhibitor may be selected from 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1, 15:1, 10:1, 5:1, 4:1, 3:1, 2:1, 1.5:1. In some embodiments, the ratio of inhibitor to accelerator may be selected from 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1, 15:1, 10:1, 5:1, 4:1, 3:1, 2:1, 1.5:1. The ratio of the one or more polarizing additives to the one or more depolarizing additives can depend in part on the aspect ratio of the feature to be plated. For example, in some embodiments, features with an aspect ratio between about 1:3 and about 3:1 may require a ratio of additives (polarizing additive to depolarizing additive) in the range of about 1:5 to about 10:1.

[0093] The one or more depolarizing additives are present in the electrolyte at a concentration between about 100 mg / L and about 1000 mg / L, more preferably between about 150 mg / L and about 500 mg / L, or about 300 mg / L for some structural geometries, and more preferably between about 500 mg / L and about 1000 mg / L, or about 750 mg / L for other structural geometries.

[0094] Components that polarize metal deposition and impart slower metal deposition rates near the openings of via features can be incorporated into the electroplating bath at concentrations between about 1 ppm and about 2000 ppm. In one embodiment, components that suppress nickel deposition rates near the openings of via features can be added to the electrolytic nickel deposition composition at concentrations between about 1 ppm and about 1000 ppm or more, preferably between about 100 ppm and about 500 ppm.

[0095] The bottom-up filling of the vias and trenches is believed to occur due to differences in the transport and adsorption rates of the additives at the surface (often referred to as the "field") and at the bottom of the vias or trenches. The concentration of the one or more polarizers at the field can be much greater than at the bottom of the vias and trenches, where electrolyte convection is geometrically limited due to their transport and adsorption rates. Conversely, the concentration of the one or more depolarizers at the bottom of the vias and trenches can be higher than at the field because the depolarizer molecules must compete with the polarizer molecules for adsorption.

[0096] The nickel electrodeposition chemistry used for via fill can be any of those known to those skilled in the art, including, for example, Watts nickel bath (mixed sulfate / chloride), Barrett nickel bath (sulfamate), all sulfates, all chlorides, organic acid sulfonates, phosphonates, fluoroborates, and mixtures thereof.

[0097] In addition, the nickel electrodeposition composition may contain an anti-pitting additive (wetting agent). Suitable anti-pitting additives include anionic surfactants such as sodium lauryl ethoxy sulfate, sodium lauryl ethoxy sulfonate and other similar compounds. Anti-pitting additives can be used to avoid pitting caused by the adhesion of air and hydrogen bubbles.

[0098] As described herein, the nickel electrodeposition composition may contain at least one buffering agent. Preferably, in addition to the at least one acid in the composition, at least one buffering agent is added to the nickel electrodeposition composition. Suitable buffering agents include, but are not limited to, salts of weak organic or inorganic acids, such as phthalates, citrates, acetates, succinates, oxalates, tartrates, phosphates, borates, and the like.

[0099] In some embodiments, the electrolyte may be heated at 20° C. to 70° C., more preferably 40° C. to 60° C. In some embodiments, the electrolyte may be agitated by stirring, sonication, or other methods.

[0100] In some embodiments, the pH of the electrodeposition composition is in the range of 2 to 5, preferably in the range of 3 to 4.5.

[0101] In some embodiments, the current density may be between 0.5 ASD and 30 ASD. More preferably, for some applications, the current density may be between 1 ASD and 5 ASD. In some embodiments, the current density may be 5 ASD.

[0102] In some embodiments, for some applications, the plating time can be 1 minute to 60 minutes. More preferably, the plating time can be 1 minute to 45 minutes, which depends on application requirements. Those skilled in the art will recognize that the plating time and current density can be adjusted to achieve target thickness.

[0103] Without being bound by theory of operation, filling vias with nickel additives can be based on adsorption CDA that relies on convection. For copper, which is expected to share similarities with nickel, the filling mechanism is complex because this type of deposition method utilizes three types of organic additives (accelerators, suppressors, and levelers) to fill microvias from the bottom up. The filling performance of copper plating solutions does not necessarily depend on the concentration of each additive independently, but may be affected by the interaction between these additives. For example, some studies have shown that the inherent functions and interactions between additives are affected in the presence of chloride ions.

[0104] The adsorption of chloride ions on the cathode is potential-dependent due to their negative charge. Therefore, convection, rather than diffusion and migration, may be primarily responsible for the transport of chloride ions to the cathode during plating. The specific function of these organic additives depends on the surface coverage of chloride ions on the cathode. Suppressors and levelers can only work at high surface coverage of chloride ions, while promoters work at low surface coverage of chloride ions. Therefore, strong forced convection leads to relatively slow metal deposition because the cathode reaction is dominated by the suppressing species under conditions of high chloride ion coverage; weak forced convection leads to relatively fast metal deposition because the cathode reaction is dominated by the promoting species under conditions of low chloride ion coverage.

[0105] Likewise, for nickel plating solutions, the ratio of additives can affect the performance of the electrodeposition composition. In some embodiments, the ratio between accelerator and suppressor can be adjusted to achieve optimal filling of various via sizes and aspect ratios.

[0106] In one aspect, the present invention is directed to providing an electrodeposition composition and method for making nickel interconnects that does not include boric acid. It is expressly contemplated that this concept and the following embodiments are used in combination with any of the preceding embodiments. Thus, while the electrodeposition composition can, and preferably does, contain an acid, the acid is selected from other acids suitable for electrodeposition. Non-limiting examples include sodium or potassium tetraborate, sulfosalicylate, acetate, succinate, tartrate, phthalate, citrate, sulfosalicylic acid, salicylic acid, acetic acid, succinic acid, and phthalic acid.

[0107] In one aspect, the present invention is directed to providing an internal stress modifier / stress controller in an electrodeposition composition and method for via fill metallization.It is expressly contemplated that this concept and the following embodiments be used in combination with any of the preceding embodiments.

[0108] In some embodiments, the present invention as a whole relates to adding anions to the bath by separate additives or utilizing metal halides as salts to adjust the internal stress based on the desired conditions. In some embodiments, the anion may be a halide ion. For example, chlorides can be used to change the internal stress from high compressive stress to neutral to low tensile stress, which may be desirable for compensating for another high compressive metal layer in the metal stack. Examples of suitable stress modifiers include, but are not limited to, chlorides, bromides, sulfonates, salicylates, sulfosalicylates, sulfonimides, etc., such as potassium chloride. The stress modifier can be included in the electrodeposition composition at a concentration in the range of about 5 g / L to about 100 g / L, more preferably in the range of about 50 g / L to about 75 g / L.

[0109] In embodiments where the metal to be deposited is nickel, the halide ions may be used as additives to nickel sulfate or nickel sulfamate based electrolytes, or as counterions to nickel as part of a nickel salt for the electrolyte composition.

[0110] The amount of internal stress can be measured by any technique known to those skilled in the art. For example, deposit test strips approved by ASTM standard B975 are widely used to measure the internal stress of coatings and films deposited on substrates.

[0111] In the following examples, exemplary electrodeposition compositions were studied for filling vias by electrodeposition of nickel. The extent of filling of the exemplary embodiments was imaged by SEM cross-sections of the vias.

[0112] Example 1: Preparation of an exemplary nickel electrolyte composition comprising the following components:

[0113] MacDermid Enthone Nickel Sulfamate LIQ 20 Concentrate (150g / L Ni) - 485mL / L

[0114] Sulfamic acid - 1.7g / L

[0115] Boric acid-30g / L

[0116] Nickel bromide solution - 55mL / L

[0117] 08-0.5g / L

[0118] MacDermid Enthone Brightener 63 (Accelerator or Depolarizer) - 3mL / L

[0119] The pH of the electrolyte was adjusted to 4.0 using a 50 g / L sulfamic acid solution and the electrolyte was heated to 55°C. A 2 cm x 2 cm coupon with a 23 μm diameter, 30 μm deep via with a copper seed layer and patterned photoresist was taped to a stainless steel coupon holder, immersed in the electrolyte and electroplated for 10 minutes at a current density of 5 ASD with the electrode rotating at a rotation rate of 100 RPM. The photoresist was stripped and a SEM cross-section showed that the via was filled to approximately 50%.

[0120] Example 2: The same electrolyte as Example 1 was prepared by adding 2 mL / L of compound S2, a heterocyclic betaine (polarizer) with a molecular weight less than 500. The photoresist was stripped and SEM cross-sections showed that the vias were filled to about 60%.

[0121] Example 3: Adding 4 mL / L of compound S2 prepared the same electrolyte as Example 1. The photoresist was stripped and SEM cross-section showed that the vias were filled to about 100%.

[0122] Example 4: Addition of 8 mL / L of compound S2 The same electrolyte as in Example 1 was prepared. The photoresist was stripped and the SEM cross section showed that 100% of the vias were filled with small overburden bumps on top.

[0123] Figure 4 shows a graph of constant current chronopotentiometry according to Examples 1 to 4. The figure shows a constant current experiment in which compound S2 was injected at different concentrations and different electrode rotation speeds. The experiment was carried out at 55°C with 5ASD. For each example, the electrode was rotated at 200 rpm and 1000 rpm, and the potential difference between the fast rotation and the slow rotation is indicated in the figure. In Example 1, which contains a promoter but no S2, the potential difference is -7 mV, which indicates depolarization and can be regarded as a possible indication that the sample will lead to conformal growth. Examples 2-4, which contain increasing concentrations of S2, show the opposite effect, where the potential difference is positive. One of ordinary skill in the art will understand that this electrochemical analysis is an indication of bottom-up filling. Therefore, without being bound by theory of operation, the results provide an indication that the addition of S2 illustrates bottom-up filling.

[0124] Example 5: Adding 1 mL / L of compound S3 (an alkynol) The same electrolyte as Example 1 was prepared. The photoresist was stripped and SEM cross-section showed that 25% of the vias were filled.

[0125] Example 6: The same electrolyte as in Example 1 was prepared with 2 mL / L of compound S4 (an enol). The photoresist was stripped and SEM cross-section showed that 45% of the vias were filled.

[0126] Example 7: The same electrolyte as in Example 1 was prepared with 20 mL / L of compound S5 (hydroxylated heterocyclic betaine). The photoresist was stripped and SEM cross-section showed that 100% of the vias were filled.

[0127] Example 8: The same electrolyte as Example 1 was prepared with 20 mL / L of compound S6 (vinyl heterocyclic betaine). The photoresist was stripped and SEM cross-section showed that 100% of the vias were filled.

[0128] Comparative Example 1: An electrolyte identical to Example 1 was prepared, except that Compound S1 / A1 (an arylsulfonamide) was omitted from the electrolyte composition. The photoresist was stripped and an SEM cross-section showed that no vias were filled to any significant extent.

[0129] Comparative Example 2: An electrolyte identical to Example 1 was prepared, except that Compound S1 / A1 (an arylsulfonamide) was omitted from the electrolyte composition. Instead, 4 mL / L of Compound S2 (a heterocyclic betaine) was added to the composition. The photoresist was stripped, and an SEM cross-section showed that no vias were filled to any significant extent.

[0130] Example 9: An electrolyte identical to that of Example 1 was prepared, except that 40 g / L potassium tetraborate was used instead of boric acid. The pH was adjusted to 4.0 with sulfamic acid, and the solution was heated to 55°C. The internal stress was measured according to ASTM B975, and the compressive stress was found to be -99.6 MPa.

[0131] Example 10: An electrolyte identical to Example 9 was prepared, except that 64 g / L potassium chloride was added. The pH was adjusted to 4.0 with sulfamic acid, and the solution was heated to 55°C. The internal stress was measured according to ASTM B975, and the tensile stress was found to be 35.9 MPa.

[0132] As shown in Examples 9 and 10, adding 64 g / L potassium chloride to the electrolyte reverses the polarity of the internal stress from compressive to tensile.

[0133] Example 11: The same electrolyte as in Example 1 was prepared, except that 45 g / L sulfosalicylic acid was added instead of 30 g / L boric acid. 12 mL / L of Compound S2 was also added. A 1.3 cm x 1.3 cm coupon with a via of approximately 20 microns in diameter and approximately 8 microns deep, with a copper seed layer and patterned photoresist, was taped to a stainless steel coupon holder, immersed in the electrolyte, and electroplated at a current density of 5 ASD for 3 minutes at a rotation rate of 50 RPM. The photoresist was stripped, and an SEM cross-section indicated that the via was approximately 100% filled. Internal stress was measured according to ASTM standard B975 and found to be -74.9 MPa in compression.

[0134] Example 12: The same electrolyte as in Example 1 was prepared. A 3.0 cm x 3.0 cm coupon with approximately 20 μm diameter openings in photoresist lined with a PVD copper seed layer was taped to a stainless steel coupon holder, immersed in the electrolyte, and electroplated for 3 minutes at a spin rate of 20 RPM at a current density of 5 ASD. The photoresist was stripped, and a SEM cross-section revealed 3 μm thick nickel pillars suitable for UBM applications.

Claims

1. A nickel electrodeposition composition for filling vias and / or trenches in microelectronic devices with nickel or a nickel alloy selected from the group consisting of NiCo, NiMo and NiCoFe, the nickel electrodeposition composition comprising: a) nickel ion source; b) 100 to 500 ppm of one or more polarizing additives, wherein the one or more polarizing additives comprise a substituted, polysubstituted, or unsubstituted heterocyclic betaine, or an enol, or a combination thereof; c) 100 to 750 mg / L of one or more depolarizing additives, wherein the one or more depolarizing additives comprise sulfimides, sulfonates, sulfates, or combinations thereof; and d) 50 to 100 g / L of a stress modifier, wherein the stress modifier is selected from the group consisting of chlorides, bromides, sulfonates, salicylates, sulfosalicylates, and sulfonimides; wherein the composition does not contain boric acid, and The composition is configured to completely fill vias and / or trenches in a microelectronic device by bottom-up filling of the vias and / or trenches.

2. The composition of claim 1, wherein the composition further comprises an acid selected from the group consisting of oxalic acid, citric acid, sulfamic acid, acetic acid, salicylic acid, sulfosalicylic acid, succinic acid, phthalic acid, tartaric acid, and salts of any of the foregoing.

3. The composition of claim 1 or 2, wherein the nickel ion source is selected from the group consisting of nickel carboxylates, nickel chloride, nickel bromide, nickel sulfate, nickel sulfamate, nickel fluoroborate, and nickel pyrophosphate.

4. The composition of claim 3, wherein the nickel ion source is nickel acetate.

5. The composition according to claim 1 or 2, wherein the composition further comprises a surfactant, wherein the surfactant is an anionic surfactant, a cationic surfactant or a nonionic surfactant.

6. The composition of claim 1, wherein the ratio of the one or more polarizing additives to the one or more depolarizing additives is in the range of 100:1 to 1:

100.

7. The composition of claim 1 or 2, wherein the composition further comprises a buffer, wherein the buffer comprises a salt of a weak organic or inorganic acid selected from the group consisting of phthalates, citrates, acetates, succinates, oxalates, tartrates, phosphates, borates, and combinations of one or more of the foregoing.

8. The composition according to claim 1 or 2, wherein the pH of the composition is in the range of 2 to 5.

9. A method of filling vias and / or trenches in a microelectronic device with nickel or a nickel alloy selected from the group consisting of NiCo, NiMo, and NiCoFe, the method comprising the steps of: contacting a substrate comprising vias and / or trenches, wherein the vias and / or trenches have a copper seed layer disposed thereon, with an electrodeposition composition, wherein the electrodeposition composition comprises: a. Nickel ion source; b. 100 to 500 ppm of one or more polarizing additives, wherein the one or more polarizing additives comprise a substituted, polysubstituted or unsubstituted heterocyclic betaine, or an enol, or a combination thereof; c. 100 to 750 mg / L of one or more depolarizing additives, wherein the one or more depolarizing additives comprise sulfimides, sulfonates, sulfates, or combinations thereof; and d. 50 to 100 g / L of a stress modifier, wherein the stress modifier is selected from the group consisting of chlorides, bromides, sulfonates, salicylates, sulfosalicylates, and sulfonimides; wherein the composition does not contain boric acid, wherein the vias and / or trenches are contacted with the electrodeposition composition for a period of time sufficient to completely fill the vias and / or trenches by bottom-up filling of the vias and / or trenches, and The electrodeposition composition is configured for bottom-up filling of the vias and / or trenches.

10. The method of claim 9, wherein the substrate is contacted with the electrodeposition composition for between 1 minute and 60 minutes.

11. The method of claim 9, wherein the electrodeposition composition is heated to a temperature between 20°C and 70°C.

12. The method according to any one of claims 9 to 11, wherein the electrodeposition composition is stirred.

13. The method according to claim 9, wherein the electrodeposition composition further comprises a surfactant, wherein the surfactant is an anionic surfactant, a cationic surfactant, or a nonionic surfactant.

14. The method of claim 9, wherein the electrodeposition composition further comprises a buffer, wherein the buffer comprises a salt of a weak organic or inorganic acid selected from the group consisting of phthalates, citrates, acetates, succinates, oxalates, tartrates, phosphates, borates, and combinations of one or more of the foregoing.

15. The method of claim 9, wherein the aspect ratio of the vias and / or trenches is between 1:3 and 3:1, and the ratio of polarizing additive to depolarizing additive is in the range of 1:5 to 10:

1.

16. The method of claim 9, wherein the electrodeposition composition comprises a stress modifier, wherein the stress modifier is capable of reversing the polarity of the internal stress of the electrodeposited nickel from compression to tension, wherein the internal stress of the electrodeposited nickel is determined by ASTM Standard B975.

17. The method of claim 16, wherein the stress modifier is selected from the group consisting of bromides, sulfonates, salicylates, sulfosalicylates, and sulfonimides.

18. The method of claim 9, wherein the electrodeposition composition further comprises an acid, wherein the acid is selected from the group consisting of oxalic acid, citric acid, sulfamic acid, salicylic acid, sulfosalicylic acid, succinic acid, phthalic acid, tartaric acid, and salts of any of the foregoing.

19. The method of claim 18, wherein the acid comprises sulfamic acid.

20. A nickel electrodeposition composition for filling vias and / or trenches in a microelectronic device with nickel or a nickel alloy selected from the group consisting of NiCo, NiMo, and NiCoFe, the nickel electrodeposition composition comprising: a) nickel ion source; b) at least one acid; c) 100 to 500 ppm of one or more polarizing additives, wherein the one or more polarizing additives comprise a substituted, polysubstituted, or unsubstituted heterocyclic betaine, or an enol, or a combination thereof; d) 100 to 750 mg / L of one or more depolarizing additives, wherein the one or more depolarizing additives comprise sulfimides, sulfonates, sulfates, or combinations thereof; e) at least one surfactant; f) at least one buffer; and g) a stress modifier, wherein the stress modifier is selected from the group consisting of: bromides, sulfonates, salicylates, sulfosalicylates, and sulfonimides; wherein the nickel electrodeposition composition does not contain boric acid, and The nickel electrodeposition composition is configured to completely fill vias and / or trenches in a microelectronic device by bottom-up filling of the vias and / or trenches.

21. The nickel electrodeposition composition of claim 20, wherein the ratio of polarizing additive to depolarizing additive is in the range of 1:5 to 10:1.

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