KR20030029004A - Plating bath and method for depositing a metal layer on a substrate - Google Patents

Abstract

PURPOSE: A plating bath and a method for improving deposition of a metal on a substrate by including hydroxylamines in the plating bath that prevent the degradation of plating bath components are provided. CONSTITUTION: The metal plating bath comprising an additive consumption inhibiting compound having formula 1, (R1-NHR2-OH)nX, where R1 and R2 are each independently hydrogen, C1-C6 alkyl, n is 1 or 2, when n is 1, X is HSO4¬-, H2PO4¬-, NO3¬-, F¬-, Cl¬-, Br¬- or I¬- and when n is 2, X is SO4¬2-; and metal salts of copper, gold, silver, palladium, platinum, cobalt, cadmium, chromium, nickel, bismuth, indium, tin, rhodium, lead, ruthenium, iridium, or alloys thereof, wherein the C1-C6 alkyl comprises methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, isohexyl, 3-methylpentyl, 2,2-dimethylbutyl, or 2,3-dimethylbutyl, wherein the additive consumption inhibiting compound comprises hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine chloride or mixtures thereof, wherein the additive consumption inhibiting compound comprises from about 0.001 g/L to about 100 g/L of the bath, wherein the additive consumption inhibiting compound comprises from about 0.01 g/L to about 20.0 g/L of the bath, and wherein the metal plating bath further comprises additives comprising brighteners, levelers, hardeners, wetting agents, malleability modifiers, ductility modifiers, deposition modifiers, or suppressors.

Description

Plating bath and method for depositing a metal layer on a substrate

The present invention relates to a plating bath and method for improving metal deposition on a substrate. More specifically, the present invention relates to plating baths and methods for enhancing metal deposition on a substrate by including hydroxylamine in the plating bath to prevent decomposition of the plating bath components.

Deposition of metals on substrates is used in various industrial applications such as electroforming, electrorefining, copper powder manufacturing, electroplating, electroless plating and the like. Methods of plating substrates with metals include sanitary appliances, automotive parts, jewelry and furniture accessories, various electrical devices and circuits such as printed wiring and circuit boards, electrolytic foils, silicon wafer plating. It is used for manufacture of these. Examples of metals that can be plated on a substrate include copper, gold, silver, palladium, platinum, zinc, tin, nickel, lead, cobalt and alloys thereof. Although many metals are used for plating in the manufacture of ornaments and electrical devices, copper is one of the most common plating metals. The electronics industry uses copper extensively as a metal to manufacture printed wiring and circuit boards as well as other electronic products.

The electronics industry requires some conditions for copper deposits on printed wiring boards. For example, upon thermal shock (288 ° C., immersing at least once for 10 seconds in a liquid tin / lead solder), the copper layer should not form any cracks. In addition, the copper layer should be flat throughout the coating surface and uniform in thickness. In addition, the deposition process must be easy to handle and economical.

Anodes that can decompose during electroplating, for example copper anodes, are often used in copper electroplating. Such anodes are known in the industry as soluble anodes. The soluble anode may be in the form of a plate, bar or sphere. The plate and bar are connected to the power supply by suitable fixing means. Spears are often introduced in baskets made of titanium. These spheres are connected to the power supply by suitable securing means. Such an anode decomposes at about the same rate during deposition as copper is deposited from the deposition bath and the amount of copper in the deposition solution remains nearly constant. Therefore, there is no need to replenish copper.

Another type of anode is an insoluble anode. The external dimensions of the insoluble anode do not change during the metal deposition process. This anode consists of an inert material such as titanium or lead that is coated with a catalytic metal such as platinum to prevent excessive anode overvoltage. Insoluble anodes are preferred over soluble anodes in printed wiring and circuit board manufacture. Electroplating with insoluble anodes is much more versatile than plating with consumable electrodes, with faster plating speed, smaller device size, easier maintenance, improved solution flow and stirring, and insoluble anodes Place them in very close proximity. It is particularly advantageous that the size of the insoluble anode does not change (ie, the cell geometry remains fixed). Thus, more uniform plating is obtained. In addition, copper salts used to provide copper sources are often obtained as etch process products associated with the manufacture of copper plating apparatus. For example, in the manufacture of circuit boards, a copper layer is pressed across the surface of an insulated substrate and then the copper portions are etched to produce the desired circuit board.

Plating a metal on a substrate, for example electroplating using copper, is widely used in various manufacturing processes. As additional binder layers for metal layers, copper plating is used to prevent corrosion on various surfaces (ie iron surfaces), increase electrical or thermal conductivity, and provide conductive paths in many electrical applications. Electroplating using copper is used in the manufacture of electrical devices such as circuit boards, integrated circuits, electrical contact surfaces and the like.

Plating a metal is a complex process involving several components in a plating bath. In addition to metal salts, pH adjusters and surfactants or wetting agents that provide metal sources, many plating baths, such as electroplating baths, contain chemical compounds that enhance various aspects of the plating process. Such chemical compounds or additives may be used for the macro-uniform electrodeposition as well as the brightness of the metal plating, the physical properties of the plating metal, in particular the ductility and micro-throwing power of the bath. Auxiliary bath component used to improve throwing power. Of particular interest are additives that affect the gloss, flatness and uniformity of the metal deposits on the surface. It is important to maintain the bath concentration of the additive within precise tolerances in order to obtain high quality metal deposits. The additive is destroyed during metal plating. The additive is destroyed by oxidation at the anode, reduction at the cathode and chemical decomposition. If additives are destroyed during plating, the properties of the metal layer deposits may be less than satisfactory to industrial standards due to the products broken down. Additives have been added regularly based on empirical rules established by industry workers to try and maintain the optimal concentration of additives. However, it is still very difficult to monitor the additive concentration to improve metal plating because the additive is present in the plating bath in small amounts, ie parts per million per solution. In addition, a complex mixture of additives and decomposition products formed from additives during plating complicates the replenishment process. In addition, the consumption of certain additives is not always constant with time or the bath used. Thus, the concentration of certain additives is not exactly known, and the level of additives in the bath eventually increases or decreases to levels outside the allowable range. If the additive content falls considerably from the allowable range, the quality of the metal deposits will degrade, and the deposits can become cloudy and / or crumbly or powdery in appearance. Another result is poor uniform electrodeposition and / or poor flatness, including plating folding. Electroplating through-hole interconnections in the manufacture of multilayer printed circuit boards is one example where high quality plating is required.

The stability and lifespan of the plating bath is very important. The life of the plating bath can be extended by increasing the stability of the additive which improves the metal plating. Longer plating baths are economically important. Frequently changing the plating bath and treating the bath containing the degraded additives, as mentioned above, interrupts the metal plating process. This interruption lowers the yield of the product. Therefore, a stable plating bath that prevents or reduces the destruction of additives is highly desired.

US 4,469,564 discloses a copper electroplating method known to increase electroplating bath life. This patent suggests that this method can be used with soluble or insoluble anodes. The cation-permeable membrane surrounds the anode to prevent the organic additives from being oxidized by the anode in contact with the anode. A disadvantage of this method is that the cation-permeable membrane is exposed to corrosive chemicals for a long time, which can corrode the membrane. For example, the pH range of the bath can be as high as less than 1.0 to 11.0 and more. In addition, the pH range of the bath may vary over time as the bath components are consumed or destroyed. Therefore, those skilled in the art must select a membrane having a chemical composition that is not destroyed by pH variations during electroplating. In addition, as described above, the electroplating bath contains various components. Components such as organic additives or breakdown products thereof can block the pores of the cation-permeable membrane, preventing cations from passing through the bath. Therefore, those skilled in the art should replace the membrane after stopping the electroplating process. Pore containment and process interruption reduce the efficiency of metal electroplating.

Japanese Patent Application No. 63014886 A2 discloses an acid copper electroplating bath containing chloride ions and also transition metal ions at 0.01 to 100 g / l. It has been reported that electroplating baths do not consume organic additives. Organic additives here include brighteners, leveling agents, curing agents, malleability and ductility improvers, and deposition modifiers.

EP 0402 896 describes a method for stabilizing organic additives such as brighteners in acid copper electroplating solutions. This method used a soluble anode of copper chips in a titanium basket. Transition metal salts of manganese, iron, chromium and titanium were added to the electroplating solution at concentrations of 5 g / l or less. The transition metal may exist in more than one positive oxidation state, but in solution is substantially in its usual lowest positive oxidation state. It has been reported to stabilize organic additives by the presence of transition metal ions in both oxidation states in solution.

US Pat. No. 6,099,711 describes an electroplating method using an insoluble anode that supplements metal ions, for example copper ions, to an electroplating bath using a metal ion generator in the form of a reversible redox system. Since insoluble anodes are used instead of soluble anodes, metal ions are not supplemented to the bath by melting of the anodes. Thus, a reversible redox system replenishes metal ions. Iron (II) and iron (III) compounds are used as electrochemically reversible redox systems. Another redox system described in this patent includes titanium, cerium, vanadium, manganese and chromium metals. These metals deposit copper in the form of iron (II) -7 hydrate, iron (II) -9 hydrate, titanyl-sulfuric acid, cerium (IV) sulfate, sodium metavanadate, manganese (II) sulfate or sodium chromate May be added to the solution. The patent suggests that redox systems can be combined.

In addition to replenishing metal ions in the electroplating bath, the patent described that the disclosed method prevents the decomposition of organic additives to a significant extent. Degradation of large amounts of organic additives in the bath occurs electrolytically at the anode due to the anode potential. Those skilled in the art are convinced that the redox reaction potential (about 0.530 V vs SCE) from iron (II) to iron (III) will provide an anode potential low enough to prevent brightener oxidation at the anode. Thus, the consumption of brighteners is reduced. Such organic additives include brightening agents, leveling agents and wetting agents. The brighteners used are water soluble sulfur compounds and high molecular weight oxygen-containing compounds. Other additive compounds include nitrogenous sulfur compounds, polymeric nitrogen compounds and / or polymeric phenazonium compounds.

The patent claims to replenish metal ions and reduce gloss consumption, but US Pat. No. 6,099,711 has disadvantages. Instead of oxidizing copper to copper (II), iron (III) can be reduced back to iron (II) by a reversible redox reaction. In addition, over time, iron may accumulate in the system, causing a problem of stopping the process and requiring a cleaning step. This step reduces process efficiency and increases production costs. Another problem with this method is that the concentration of the compound in the redox system must be adjusted such that the concentration of metal ions remains constant in the deposition solution. Accordingly, there is a margin of error that is slightly or nonexistent in the concentration of redox compounds in the deposition solution for process operation. Thus, slight changes in the redox compound concentration can interfere with process operation.

Japanese Patent Application No. 96199385 discloses an electroplating method and solution containing organic additives such as fluoride-based surfactants and brightening agents. The addition of fluoride-based surfactants has been reported to prevent the consumption of brighteners.

Although there is a method of preventing the decomposition of the additive in the metal plating bath, a further method of preventing the decomposition of the bath additive is still desired.

TECHNICAL FIELD This invention relates to the plating tank containing hydroxylamine which suppresses consumption of an additive in a plating tank, and the method of plating a metal on a board | substrate using this plating tank. Such hydroxylamines include compounds of formula (1):

(R ¹ -NHR ² OH) _n X

Where

R ¹ and R ² are each independently hydrogen or C ₁ -C ₆ alkyl,

n is 1 or 2,

when n is 1 and X is ^{_{HSO 4 -, H 2 PO 4}} -, NO 3 -, F -, Cl -, Br - or I ^-, and

When n is 2, X is SO ₄ ^2- .

The aforementioned hydroxylamines can be used in metal plating baths for plating copper, gold, silver, palladium, platinum, cobalt, cadmium, chromium, nickel, bismuth, indium, tin, rhodium, lead, iridium, ruthenium or alloys thereof. have.

Advantageously, the addition of hydroxylamine to the plating bath prevents or reduces decomposition of the metal plating bath additive. In this way, hydroxylamine provides an extended lifetime plating bath and efficient metal plating method. In addition, since the hydroxylamine of the present invention prevents decomposition of the additive, the plating bath of the present invention provides a uniform, high gloss metal layer having good physical-mechanical properties on the substrate.

The metal plating bath of the present invention can be used to plate a metal layer on a substrate that can be metal plated. The metal plating method of the present invention comprises passing a current between two electrodes immersed in a bath containing dissolved plating metal, bath additives, and at least one additive consumption inhibiting hydroxylamine compound according to the present invention. Current is passed through the bath until the substrate is plated with metal of the desired thickness.

The hydroxylamines and methods of the present invention can be used anywhere in the industry where metal plating is used. For example, metal plating baths can be used for electrical devices such as printed circuits and wiring boards, integrated circuits, electrical contact surfaces and connectors, electrolytic foils, microchip applied silicon wafers, semiconductors and semiconductor packaging, and lead frames. , Optoelectronics and optoelectronics packaging, for example in the manufacture of solder bumps on wafers and the like. Metal plating baths can also be used to metal plate ornaments in jewelry, furniture accessories, automotive parts, sanitary appliances, and the like. Furthermore, hydroxylamine can also be used in waste treatment methods.

The invention also includes an apparatus consisting of a metal plating bath containing an electrical power source, an anode, a cathode and an additive consumption inhibiting hydroxylamine compound. In such a device the cathode is a metal plated part. This apparatus may be a vertical or horizontal metal plating apparatus.

It is a first object of the present invention to provide hydroxylamine which prevents or reduces the decomposition of additives in metal plating baths.

Another object of the present invention is to provide a metal plating bath with a long lifetime.

It is a further object of the present invention to provide an efficient method for plating metal on a substrate.

It is also an object of the present invention to provide a method for plating a uniform, high gloss metal layer having good physico-mechanical properties on a substrate.

Another object of the present invention is to provide a device having a metal plating bath containing hydroxylamine.

Those skilled in the art will recognize further objects and advantages after reading the detailed description of the invention and the appended claims.

1 is a schematic view of an apparatus for processing a workpiece by a vertical method according to the present invention.

2 is a schematic diagram of an apparatus for processing a workpiece by a horizontal method according to the present invention.

The metal plating bath of the present invention contains hydroxylamine which prevents or reduces the consumption of additives added to the metal plating bath to improve metal deposition on the substrate. The metal plating bath can be used in any method as long as it is a suitable method for plating metal on a substrate. The hydroxylamine has the formula (1)

[Formula 1]

(R ¹ -NHR ² OH) _n X

Where

R ¹ and R ² are each independently hydrogen or C ₁ -C ₆ alkyl,

n is 1 or 2,

when n is 1 and X is ^{_{HSO 4 -, H 2 PO 4}} -, NO 3 -, F -, Cl -, Br - or I ^-, and

When n is 2, X is SO ₄ ^2- .

Examples of C ₁ -C ₆ alkyl are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, isopentyl, neopentyl, t-pentyl, hexyl, isohexyl, 3- Methylpentyl, 2,2-dimethylbutyl and 2,3-dimethylbutyl.

Preferred hydroxylamines are hydroxylamines in which R ¹ and R ² are hydrogen, for example hydroxylamine sulfate, hydroxylamine nitrate and hydroxylamine chloride. Most preferred are hydroxylamine sulfate and hydroxylamine nitrate. The aforementioned additive consumption inhibiting compounds are either commercially available or can be synthesized according to methods well known in the art.

The aforementioned compounds can be used in metal plating baths for plating copper, gold, silver, palladium, platinum, cobalt, chromium, cadmium, nickel, bismuth, indium, tin, iridium, ruthenium, rhodium, lead or alloys thereof. Preferably, the aforementioned compounds can be used in metal plating baths for plating metals consisting of copper, gold, platinum, silver, palladium, iridium, ruthenium and cobalt. More preferably, the aforementioned additive consumption inhibiting compounds are used in metal plating baths for plating copper, iridium and ruthenium. Most preferably, the metal plating bath is for copper plating. The metals are included in the metal plating bath in the form of water soluble salts.

The addition of one or more hydroxylamines to the metal plating bath prevents or reduces degradation of the additives in the metal plating bath. Preferably, the metal plating bath is an electroplating bath. The hydroxylamine is generally added in an amount of about 0.001 to about 100 g / l of the bath. Preferably, the compound is generally used at about 0.01 to about 20.0 g / l in the plating bath. The additive preserving hydroxylamine compound may be added to the plating bath in any manner so long as it is a suitable method used to add components to the bath. One method is to mix the hydroxylamine with the other bath components and additives in a plating bath.

Additives that are prevented or significantly reduced in degradation by hydroxylamine include, but are not limited to, brightening agents, leveling agents, curing agents, wetting agents, malleable, ductile and deposition improvers, inhibitors and the like. The additive protective hydroxylamine compounds of the present invention are particularly effective in preventing degradation of brightening and leveling agents. Although the hydroxylamine of the present invention can be used to prevent decomposition of additives used in various metal plating baths, it is preferred that hydroxylamine be used to prevent decomposition of additives used in copper baths.

Examples of suitable brighteners used in the plating bath of the present invention are the general formula HO ₃ SR ¹¹ -SH, HO ₃ SR ¹¹ -SSR ¹¹ -SO ₃ H or HO ₃ S-Ar-SS-Ar-SO ₃ H (in these formulas, R ¹¹ is a C ₁ -C ₆ alkyl or aryl group, and Ar is phenyl or naphthyl). Substituents of alkyl and aryl groups can be, for example, alkyl, halo and alkoxy. Examples of such brighteners include 3-mercapto-propylsulfonic acid (sodium salt), 2-mercapto-ethanesulfonic acid (sodium salt) and bissulfopropyl disulfide (BSDS). Such compounds are described in US Pat. Nos. 3,770,598, 4,374,709, 4,376,685, 4,555,315, and 4,673,469, all of which are incorporated herein by reference. Such polysulfides can also be used to increase the ductility of the deposited metal. Other examples of brighteners that are particularly suitable for copper plating include N, N-dimethyldithiocarbamic acid (3-sulfopropyl) ester, sodium salt (DPS), (O-ethyldithiocarbonato) -S- (3- Sulfopropyl) -ester, potassium salt (OPS), 3-[(amino-iminomethyl) -thio] -1-propanesulfonic acid (UPS), 3- (2-benzthiazolylthio) -1-propanesul Thiol (MPS) of phonic acid, sodium salt (ZPS) and bissulfopropyl disulfide.

Examples of planarizing agents that can be used in the plating bath include, but are not limited to, alkylated polyalkyleneimines and organic sulfo sulfonates. Examples of such compounds include 1- (2-hydroxyethyl) -2-imidazolidinethione (HIT), 4-mercaptopyridine, 2-mercaptothiazoline, ethylene thiourea, thiourea and alkylated polyalkyleneimines This includes. Such compounds are described in US Pat. Nos. 4,376,685, 4,555,315 and 3,770,598, all of which are incorporated herein by reference.

Examples of other additives that may act as a brightening agent in the plating bath within the scope of the present invention include 3- (benzthiazolyl-2-thio) -propylsulfonic acid sodium salt, 3-mercaptopropane-1-sulfonic acid sodium salt , Sodium ethylenedithiodipropylsulfonic acid salt, bis- (p-sulfophenyl) -disulfide disodium salt, bis- (ω-sulfobutyl) -disulfide disodium salt, bis- (ω-sulfohydroxypropyl) -disulfide Disodium salt, bis- (ω-sulfopropyl) -disulfide disodium salt, bis- (ω-sulfopropyl) -sulphide disodium salt, methyl- (ω-sulfopropyl) -disulfide sodium salt, methyl- (ω- Sulfopropyl) -trisulfide disodium salt, O-ethyl-dithiocarboxylic acid-S- (ω-sulfopropyl) -ester, potassium salt thioglycolic acid, thiophosphate-O-ethyl-bis- (ω-sulfopropyl) Ester disodium salt, thiophosphate-tris (ω-sulfopropyl) -ester trisodium salt, and the like, but are not limited to these.

Examples of high molecular weight oxygen-containing compounds that can be used as inhibitors include carboxymethylcellulose, nonylphenolpolyglycol ethers, octanediolbis (polyalkylene glycolethers), octanolpolyalkylene glycolethers, oleic acidpolyglycol esters, polyethylenepropylene Glycol, polyethylene glycol, polyethylene glycol dimethyl ether, polyoxypropylene glycol, polypropylene glycol, polyvinyl alcohol, stearic acid polyglycol ester, stearyl alcohol polyglycol ether, polyethylene oxide and the like.

Penazine-based (Sapranine type) and phenazine azo dyes (Janus Green B type) can be used as the leveling agent. Polyethers can be used to improve the thickness and uniformity of metal plating.

Brighteners and planarizers are added to the plating bath in amounts from about 1 parts per billion (ppb) to 1.0 g / l of the bath. Preferably, the range of brightener and leveling agent is from about 10 ppm to about 500 ppm. The range of bath components may vary depending on the bath composition. Therefore, the weight range for the aforementioned additives is a general range.

Examples of suitable wetting agents or surfactants that may be used in the plating bath of the present invention include nonionic surfactants such as alkyl phenoxy polyethoxyethanols. Other suitable wetting agents containing a plurality of oxyethylene groups may also be used. Such wetting agents include polyoxyethylene polymer compounds having 20 to 150 repeating units. Such compounds may also act as inhibitors. Block copolymers of polyoxyethylene and polyoxypropylene are also included in the polymer class. Surfactants and wetting agents are added in conventional amounts.

In addition to the additives, other plating bath components are included in the plating bath as metal ion sources, pH adjusters such as inorganic acids, and halide ion sources. Generally, the plating bath is aqueous. The pH range of the bath may be 0 to about 14, preferably 0 to about 8. Wetting agents used in plating baths and amounts used in such plating baths are well known in the art. Inorganic acids used include, but are not limited to, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and the like. Preferred acids are sulfuric acid. Halogen ions are optional. Halogen ions used in the plating bath include chloride, fluoride and bromide. These halides are added to the bath in the form of water soluble salts. Chloride is preferred and is introduced into the bath with sodium chloride, preferably HCl. The water soluble salts of the metal provide the metal source to be plated on the substrate. Such water soluble salts include metal salts of copper, nickel, chromium, gold, silver, cadmium, platinum, palladium, cobalt, bismuth, tin, rhodium, iridium, ruthenium, lead and indium. Solder may also be plated by the plating bath of the present invention.

The preferred metal to be plated by the bath of the invention is copper. Preferably, copper is electroplated. Useful copper can be in the form of any copper compound that is dissolved in the solution. Suitable copper compounds include, but are not limited to, copper halides, copper sulfate, copper alkanesulfonates, copper alkanol sulfonates, and the like. If copper halide is used, chloride is the preferred halide. Preferred copper compounds are copper sulfate, copper alkane sulfonate or mixtures thereof. More preferred are copper sulfate, copper methane sulfonate or mixtures thereof. Copper compounds useful in the present invention are generally commercially available or can be prepared by methods known in the literature. When copper is plated on the substrate, the pH range of the bath may be from 0 to about 14. Preferred baths have a pH range of 0 to about 8.0.

The concentration range of metal ions in the plating bath is from about 0.010 to about 200 g / l, preferably from about 0.5 to about 100 g / l. If copper is used, the amount of copper may range from about 0.01 to about 100 g / l. Preferably, copper is used in the bath in an amount of about 0.10 to about 50 g / l. When the bath of the present invention is used in a non-high speed plating method, the amount of copper present in the bath is preferably in the range of about 0.02 to about 25 g / l. When the bath of the invention is used in a high speed plating method, the amount of copper present in the bath is about 1.0 to about 100 g / l, preferably about 2.0 to about 50 g / l.

In particular, the concentration range of halide ions for copper baths is from 0 mg / L to about 1 g / L, preferably from about 1.0 mg / L to about 150 mg / L. The acid may be added to the plating bath such that the pH ranges from about 0 to about 8.0, most preferably less than about 1.0 to about 2.0. Thus, the acid is added in an amount of about 10 to about 600 g / l, preferably about 15 to about 500 g / l.

An example of an acid copper electroplating bath for practicing the present invention has the following composition:

Copper ion (copper sulfate) 0.01 to 50 g / l (Dark) sulfuric acid 15 to 500 g / l Chloride ions (as sodium chloride) 1 ppm to 150 ppm additive As required Hydroxylamine sulfate 0.1 to 10 g / l water Amount to be 1 liter

The hydroxylamine compound can be used to prevent degradation of the additive anywhere in the plating bath where the substrate can be plated, but it is preferred that this additive protecting hydroxylamine compound is used in the electroplating bath. Such electroplating baths are used to electrodeposit metals on substrates, such as in the manufacture of microchip applied silicon wafers and printed wiring boards and in the manufacture of other electrical device components. Electroplating methods include flowing current to the anode, electroplating solution and cathode for a time sufficient to metal plate the substrate to a desired thickness. The anode may be a soluble anode (made of a metal such as copper that is dissolved and replenished when plated in an electroplating bath). Insoluble anodes (made of inert materials such as platinum, titanium platinum, lead, etc.) may also be used. Preferably, the present invention is used in a plating method using an insoluble anode having a more severe problem related to additive consumption (often oxidized in the anode) than the method using a soluble anode but having a faster electroplating rate.

Examples of useful insoluble anodes are anodes containing oxides of iridium and tantalum on their surfaces. These anodes contain about 20 to about 90 mole percent iridium with the remainder being tantalum. It is preferred that it contains about 60 to about 90 mole percent iridium and the remainder is tantalum. A positive electrode is prepared by coating iridium and tantalum on a conductive substrate such as a titanium substrate.

Other suitable anodes include anodes composed of at least about 10 mole percent Group VIII metal, at least about 10 mole percent valve metal and at least about 5 mole percent binder metal. Group VIII metals include cobalt, nickel, ruthenium, rhodium, palladium, iridium and platinum. Valve metals include titanium, zirconium, hafnium, vanadium, niobium and tantalum. Binder metals include beryllium, calcium, strontium, barium, scandium, yttrium, lanthanum and rare earth elements with atomic numbers 58 to 71. Particularly useful are oxide compositions having a barium of about 5 to about 20 mole percent and an iridium to tantalum ratio of about 1/4 to about 4. Such compositions contain about 5 mole percent barium, about 30 to about 40 mole percent iridium, and the balance tantalum. In addition, osmium, silver and gold or oxides thereof may be used for the insoluble anode.

As mentioned above, the plating bath of the present invention can be used in any suitable plating method for plating metal on a substrate. Examples of such plating methods include, but are not limited to, direct current (DC) electroplating and pulse electroplating. The plating bath of the present invention is particularly suitable for plating substrates in electronic device manufacturing, such as in the silicon semiconductor wafer manufacturing and printed wiring board industries.

In the electroplating method, the substrate to be plated is used as the cathode. As mentioned above, a soluble or preferably insoluble anode is used as the second electrode. Pulse plating, direct current plating, or a combination of the two may be used. Such plating methods are known in the art. Current density and electrode surface potential can vary depending on the particular substrate to be plated. In general, the current density of the anode and cathode can vary within the range of about 1 to about 1000 amps / ft ² (ASF). The plating bath is maintained in a temperature range of about 20 to about 110 ° C. The specific temperature range depends on the metal to be plated. Such temperature ranges are well known in the art. The temperature range of the copper bath is about 20 to about 80 ° C. The temperature range of the acid copper bath is about 20 to about 50 ° C. Plating continues for a time sufficient to form a deposit of desired thickness. In general, the plating time for the circuit board is from about 45 minutes to about 8 hours. For circuit board fabrication, the desired thickness can range from about 0.5 to about 3.0 mils. Most layer thicknesses range from about 1.0 to 1.5 mils.

Both vertical and horizontal plating methods can be used. In the vertical method, a substrate such as a printed circuit or a wiring board is introduced in a vertical position to a container containing the plating bath solution of the present invention. The substrate serving as the cathode is positioned perpendicularly opposite the at least one anode, preferably the insoluble anode. The substrate and anode connect to a current source. Instead of regulating the current density with a current source, a voltage device can also be used that makes the voltage between the substrate and the anode constant. The plating liquid is continuously moved through the vessel by means of transport equipment such as a pump.

One example of an arrangement and apparatus suitable for treating substrates or workpieces by the vertical method is shown in FIG. 1. The apparatus 10 consists of a container 12 with a metal plating bath 14 containing additive consumption inhibiting hydroxylamine. The metal plating bath 14 can be used for copper plating, for example, and contains the aforementioned components and additives.

The workpiece 16 (cathode), for example a circuit board, and the anode 18, for example, an insoluble titanium anode coated with iridium dioxide, are immersed in the metal plating bath 14. The workpiece 16 and the anode 18 are electrically connected to the current source 20. Instead of regulating the current with a current source, a voltage device (not shown) may be used to regulate the voltage between the workpiece 16 and the anode 18. The metal plating bath 14 is continuously moved to the second container or reservoir 22 by means of a vehicle (not shown) such as a pump. The reservoir 22 in parallel with the metal plating bath 14 supplements the metal plating bath 14 with metal bath components and additives such as copper salts, brighteners, leveling agents, additive consumption inhibitor hydroxylamine and the like.

In the horizontal plating method, the substrate is conveyed to the horizontal position in the horizontal moving direction through the conveyor unit. The plating bath is continuously sprayed onto the substrate from the bottom and / or the top by a splash nozzle or flood pipe means. The anodes are arranged at regular intervals with respect to the substrate and are in contact with the plating bath by suitable device means. The substrate is moved by roller or plate means.

One example of a horizontal method and apparatus that can be used to practice the present invention is shown in FIG. A spray chamber 24 of the device 46 is formed with slots 26 at both ends to continuously convey and enter the panel 28, for example a metal plated circuit board panel, to exit the chamber 24. . While a circuit board panel is described, any suitable surface that can be plated by a horizontal device is included within the scope of the present invention. The panel 28 is supported by an idler roller 30 to move in the direction of the arrow. A series of roller brushes 32 are positioned in contact with both upper and lower surfaces of panel 28, and a series of anodes 34 are in contact with roller brushes 32 on idler rollers 30 side to bring panel 28 into account. Away from). The anode 34 is formed of a suitable metal such as titanium coated with iridium dioxide. Although any suitable anode can be used, insoluble anodes such as iridium dioxide coated titanium anodes are preferred. The anode 34 is positioned such that its upper portion abuts the upper set of idler rollers 30 and the lower portion abuts the bottom set of idler rollers 30. All anodes 34 are electrically connected in parallel with the positive terminal of the power supply 36. The negative terminal of the power supply 36 is connected to the panel 28 (cathode) to be plated. The spray jet 38, which is connected to the reservoir 42 containing the metal plating bath 40 by means of the line 44 means, the roller brush 32 as well as the roller brush 32 with respect to the spray metal plating bath 40. It is arranged below the panel 28 and the anode 34 in between. Arrows indicate the flow path of the metal bath through line 44. The metal plating bath 40 is pumped from the reservoir 42 through the line 44 by pumping means (not shown) mechanically connected to the reservoir 42. Transport mechanism means (not shown) for the panel 28 are provided to continuously move the panel 28 through the chamber 24 while maintaining electrical contact between the panel 28 and the cathode of the power supply 36. It is a conveyor-type mechanism.

By preventing additive reduction or reducing the amount thereof, the hydroxylamine compound improves the glossiness of the plating metal and improves the physico-mechanical properties of the plating metal. The metal layer plated with the bath of the present invention is not brittle or has a powdery structure. In addition, the metal layer plated with the bath of the present invention is excellent in uniform electrodeposition property and there is no plating fold. Such metal layer properties are particularly desirable for through-holes in printed circuits and wiring boards. In addition, since the compounds prevent or significantly reduce the amount of the additives decomposed during metal plating, there is little need to supplement the additives. It is also possible to prevent the additives from breaking so that the metal plating operation can be maintained for a long time without bath exchange. In addition, since the hydroxylamine compounds of the present invention inhibit the decomposition of additives, it is possible to exclude expensive semi-permeable membranes from equipment during plating. Thus, plating baths containing hydroxylamine compounds provide a much more efficient and economical metal plating method than baths containing no hydroxylamine compounds. Thus, the metal plating bath of the present invention provides an improved metal plating method. All numerical ranges in the present invention are inclusive and combinable.

Although the present invention has been described centering on electroplating processes in the printed wiring board industry, the present invention can be used in any suitable plating process. The hydroxylamine compounds may be used in electrical devices such as printed circuits and wiring boards, integrated circuits, electrical contact surfaces and connections, electrolytic foils, microchip applied silicon wafers, semiconductor and semi-fabricated packaging, lead frames, optoelectronics and optoelectronics packaging, For example, it can be used in metal plating baths in the manufacture of solder bumps on wafers. Metal plating baths can also be used to metal plate ornaments in jewelry, furniture accessories, automotive parts, sanitary appliances, and the like. In addition, the additive consumption inhibiting compound of the present invention can be used in a waste treatment method.

The following examples are provided to further illustrate the present invention and are not intended to limit the scope of the present invention.

Example 1

The consumption of polish was measured in the electroplating bath using Hull Cell. Each Hull Cell used was a dynamically regulated Hull Cell (HCHC). The bath was a copper plating bath containing the following components:

Copper Sulfate Pentahydrate 80 g / ℓ Sulfuric acid (dark) 225 g / ℓ Chloride (as sodium chloride) 50 ppm Bissulfopropyl disulfide (gloss) 1 mg / l water Amount to be 1 liter

The Hull Cell of the first experiment used a copper-covered glass-epoxy panel as the soluble copper anode and cathode. Insoluble iridium dioxide anode was used for the Hull Cell used in the second and third experiments instead of the soluble copper anode. In addition to the bath component, the Hull Cell of the third experiment contained about 1 g / l hydroxylamine sulfate. Copper was plated on a copper coated glass-epoxy cathode. Brightener consumption was measured as percent matte relative to the plated copper surface. Matte defined within the scope of the present invention means that the surface appearance of the copper plated on the cathode is cloudy or non-reflective.

Each Hull Cell experiment was performed at about 3 amps for about 2 minutes and then for about 10 minutes. Percent matting on the plated copper surface was measured after about 2 minutes and after about 10 minutes. The first Hull Cell experiment with a soluble copper anode showed percent matteness for the copper metal, which was nearly the same after about 2 minutes, even after about 10 minutes. Thus, a very small amount of polish was consumed between about 2 minutes and about 10 minutes when using a soluble copper anode.

In a second experiment in which an insoluble iridium dioxide anode was used, after about 2 minutes 30% of the copper metal became matt. After about 10 minutes almost all of the copper metal was matted. Thus, after about 10 minutes, almost all of the brightener was consumed with an insoluble iridium dioxide anode.

In a third experiment, about 1.0 mg / l hydroxylamine sulfate was added to the copper plating bath to act as a brightener consumption inhibitor. The matteness for copper plated on the negative electrode was about the same percentage after about 2 minutes and after about 10 minutes. Thus, a very small amount of polish was consumed between about 2 minutes and about 10 minutes.

Consumption of brighteners is particularly problematic when insoluble anodes are used, unlike soluble copper anodes. However, when hydroxylamine sulfate is added to the copper plating bath using an insoluble anode, consumption of the brightener is suppressed.

Claims (48)

Additive additive inhibiting compounds of formula (1) and metals composed of copper, gold, silver, palladium, platinum, cobalt, cadmium, chromium, nickel, bismuth, indium, tin, rhodium, lead, ruthenium, iridium and alloys thereof Metal plating bath containing the selected metal salt: [Formula 1] (R ¹ -NHR ² OH) _n X Where R ¹ and R ² are each independently hydrogen or C ₁ -C ₆ alkyl, n is 1 or 2, when n is 1 and X is _{^{HSO 4 -, H 2 PO 4}} -, NO 3 -, F -, Cl -, Br - or I ^-, and When n is 2, X is SO ₄ ^2- . The compound of claim 1, wherein the C ₁ -C ₆ alkyl is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, isopentyl, neopentyl, t-pentyl, hexyl, iso Metal plating bath containing hexyl, 3-methylpentyl, 2,2-dimethylbutyl or 2,3-dimethylbutyl. The metal plating bath of claim 1, wherein the additive consumption inhibiting compound comprises hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine chloride, or mixtures thereof. The metal plating bath of claim 1, wherein the additive consumption inhibiting compound is included in an amount of about 0.001 to about 100 g / l of the plating bath. The metal plating bath of claim 4 wherein the additive consumption inhibiting compound is included in an amount of about 0.01 to about 20.0 g / l of the plating bath. The method of claim 1, further comprising additives including brighteners, levelers, hardeners, wetting agents, malleability modifiers, ductility modifiers, deposition modifiers or inhibitors. Metal plating bath containing. The method of claim 6, wherein the brightener is a general formula HO ₃ SR ¹¹ -SH; HO ₃ SR ¹¹ -SSR ¹¹ -SO ₃ H; Or HO ₃ S-Ar-SS-Ar-SO ₃ H, wherein R ¹¹ is C ₁ -C ₆ alkyl or aryl group, Ar is phenyl or naphthyl, and the alkyl and aryl groups are unsubstituted or alkyl groups Metal halide, which may be substituted by halo or alkoxy group. 8. The brightening agent according to claim 7, wherein the brightener is 3-mercaptopropylsulfonic acid sodium salt, 2-mercapto-ethanesulfonic acid sodium salt, bissulfopropyl disulfide, N, N-dimethyldithiocarbamic acid (3-sulfopropyl) ester sodium Salt, (O-ethyldithiocarbonato) -S- (3-sulfopropyl) -ester potassium salt, 3-[(amino-iminomethyl) -thio] -1-propanesulfonic acid, 3- (2- A metal plating bath comprising benzthiazolylthio) -1-propanesulfonic acid sodium salt or a mixture thereof. 7. The metal plating bath of claim 6, wherein the leveling agent comprises alkylated polyalkyleneimines, organic sulfo sulfonates, phenazine dyes, phenazine azo dyes or mixtures thereof. 7. The brightening agent according to claim 6, wherein the brightener is 3- (benzthiazolyl-2-thio) -propylsulfonic acid sodium salt, 3-mercaptopropane-1-sulfonic acid sodium salt, ethylenedithiodipropylsulfonic acid sodium salt, bis- (p-sulfophenyl) -disulfide disodium salt, bis- (ω-sulfobutyl) -disulfide disodium salt, bis- (ω-sulfohydroxypropyl) -disulfide disodium salt, bis- (ω-sulfopropyl) Disulfide disodium salt, bis- (ω-sulfopropyl) -sulphide disodium salt, methyl- (ω-sulfopropyl) -disulfide sodium salt, methyl- (ω-sulfopropyl) -trisulfide disodium salt, O- Ethyl-dithiocarboxylic acid-S- (ω-sulfopropyl) -ester, potassium salt thioglycolic acid, thiophosphate-O-ethyl-bis- (ω-sulfopropyl) -ester disodium salt, thiophosphate-tri (ω Sulfopropyl) -ester trisodium salt or mixtures thereof. 7. The inhibitor of claim 6 wherein the inhibitor is carboxymethylcellulose, nonylphenolpolyglycol ether, octanediolbis- (polyalkylene glycolether), octanolpolyalkylene glycolether, oleic acidpolyglycol ester, polyethylenepropylene glycol, polyethylene glycol, A metal plating bath comprising polyethylene glycol dimethyl ether, polyoxypropylene glycol, polypropylene glycol, polyvinyl alcohol, polyethylene oxide, stearic acid polyglycol ester, stearyl alcohol polyglycol ether or mixtures thereof. The metal plating bath of claim 1 wherein the pH is from 0 to about 14.0. The metal plating bath of claim 12, wherein the pH is from 0 to about 8.0. Copper metal electroplating baths containing copper salts and additive consumption inhibiting compounds of formula (1): [Formula 1] (R ¹ -NHR ² OH) _n X Where R ¹ and R ² are each independently hydrogen or C ₁ -C ₆ alkyl, n is 1 or 2, when n is 1 and X is _{^{HSO 4 -, H 2 PO 4}} -, NO 3 -, F -, Cl -, Br - or I ^-, and When n is 2, X is SO ₄ ^2- . 15. The compound of claim 14, wherein the C ₁ -C ₆ alkyl is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, isopentyl, neopentyl, t-pentyl, hexyl, iso Copper metal electroplating bath comprising hexyl, 3-methylpentyl, 2,2-dimethylbutyl or 2,3-dimethylbutyl. 15. The copper metal electroplating bath of claim 14 wherein the additive consumption inhibiting compound comprises hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine chloride or mixtures thereof. 15. The copper metal electroplating bath of claim 14, wherein the additive consumption inhibiting compound is included in an amount of about 0.001 to about 100 g / l of the plating bath. 18. The copper metal electroplating bath of claim 17 wherein the additive consumption inhibiting compound is included in an amount of about 0.01 to about 20.0 g / l of the plating bath. 15. The copper metal electroplating bath of claim 14 further comprising an additive comprising a brightening agent, a flattening agent, a curing agent, a wetting agent, a malleability improver, a ductility improver, a deposition improver, an inhibitor or a mixture thereof. The method of claim 19, wherein the brightener is a general formula HO ₃ -SR ¹¹ -SH; HO ₃ SR ¹¹ -SSR ¹¹ -SO ₃ H; Or HO ₃ S-Ar-SS-Ar-SO ₃ H (wherein R ¹¹ is a C ₁ -C ₆ alkyl or aryl group, Ar is phenyl or naphthyl, and the alkyl and aryl groups are alkyl groups, halo or Copper metal electroplating bath comprising a compound of the invention). 20. The copper metal electroplating bath of claim 19 wherein the leveling agent comprises alkylated polyalkyleneimines, organic sulfo sulfonates, phenazine-based dyes, phenazine azo dyes, or mixtures thereof. 20. The copper metal electroplating bath of claim 19 wherein the copper metal salt comprises copper halide, copper sulfate, copper alkane sulfonate, copper alkanol sulfonate or mixtures thereof. 15. The copper metal electroplating bath of claim 14 wherein the pH is from 0 to about 8.0. The substrate is a metal salt selected from copper, gold, silver, palladium, platinum, cobalt, cadmium, chromium, nickel, bismuth, indium, tin, rhodium, iridium, ruthenium, lead and alloys thereof and additives of formula (1) Contacting with a metal plating bath containing a consumption inhibiting compound; A method of plating metal on a substrate, comprising depositing the metal on the substrate by applying a sufficient current density to the plating bath: [Formula 1] (R ¹ -NHR ² OH) _n X Where R ¹ and R ² are each independently hydrogen or C ₁ -C ₆ alkyl, n is 1 or 2, when n is 1 and X is _{^{HSO 4 -, H 2 PO 4}} -, NO 3 -, F -, Cl -, Br - or I ^-, and When n is 2, X is SO ₄ ^2- . The compound of claim 24, wherein the C ₁ -C ₆ alkyl is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, isopentyl, neopentyl, t-pentyl, hexyl, iso Hexyl, 3-methylpentyl, 2,2-dimethylbutyl or 2,3-dimethylbutyl. The method of claim 24, wherein the additive consumption inhibiting compound comprises hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine chloride, or mixtures thereof. The method of claim 24, wherein the additive consumption inhibiting compound is included in an amount of about 0.001 to about 100 g / l of the plating bath. The method of claim 24, further comprising a brightening agent, planarizing agent, curing agent, wetting agent, malleable agent, ductility improver, deposition improver, inhibitor, or mixtures thereof. The method of claim 24, wherein the brightener is a general formula HO ₃ SR ¹¹ -SH; HO ₃ SR ¹¹ -SSR ¹¹ -SO ₃ H; Or HO ₃ S-Ar-SS-Ar-SO ₃ H, wherein R ¹¹ is C ₁ -C ₆ alkyl or aryl group, Ar is phenyl or naphthyl, and the alkyl and aryl groups are unsubstituted or alkyl groups Which may be substituted by halo or alkoxy group). The method of claim 24 wherein the current density is from about 1 to about 1000 ASF. The substrate of claim 24, wherein the substrate is a printed wiring board, an integrated circuit, an electrical contact surface, a connector, an electrolyte foil, a silicon wafer, a semiconductor, a lead frame, an optoelectronic device, solder bumps on a wafer, an ornament, a sanitary Methods including appliances. Contacting the substrate with a copper metal plating bath containing a copper salt and an additive consumption inhibiting compound of formula (1); A method of electroplating copper metal on a substrate, comprising depositing copper metal on the substrate by applying a sufficient current density to the plating bath: [Formula 1] (R ¹ -NHR ² OH) _n X Where R ¹ and R ² are each independently hydrogen or C ₁ -C ₆ alkyl, n is 1 or 2, when n is 1 and X is _{^{HSO 4 -, H 2 PO 4}} -, NO 3 -, F -, Cl -, Br - or I ^-, and When n is 2, X is SO ₄ ^2- . 33. The compound of claim 32, wherein the C ₁ -C ₆ alkyl is methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, isopentyl, neopentyl, t-pentyl, hexyl, iso Hexyl, 3-methylpentyl, 2,2-dimethylbutyl or 2,3-dimethylbutyl. 33. The method of claim 32, wherein the additive consumption inhibiting compound comprises hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine chloride, or mixtures thereof. 33. The method of claim 32, wherein the additive consumption inhibiting compound is included in an amount of about 0.001 to about 100 g / l of the plating bath. 33. The method of claim 32, further comprising a brightening agent, leveling agent, curing agent, wetting agent, malleability improving agent, softening improving agent, deposition improving agent, inhibitor, or mixtures thereof. The method of claim 36, wherein the brightener is a general formula HO ₃ SR ¹¹ -SH; HO ₃ SR ¹¹ -SSR ¹¹ -SO ₃ H; Or HO ₃ S-Ar-SS-Ar-SO ₃ H, wherein R ¹¹ is C ₁ -C ₆ alkyl or aryl group, Ar is phenyl or naphthyl, and the alkyl and aryl groups are unsubstituted or alkyl groups Which may be substituted by halo or alkoxy group). 33. The method of claim 32, wherein the substrate comprises printed wiring boards, integrated circuits, electrical contact surfaces, connectors, electrolytic foils, silicon wafers, semiconductors, lead frames, optoelectronic devices, solder bumps on wafers, ornaments, sanitary instruments, and the like. 33. The method of claim 32, wherein the current density is about 1 to about 1000 ASF. A power source electrically connected to the anode and the cathode such that current can pass through the anode and the cathode; An anode and a cathode in contact with the metal plating bath such that the metal from the plating bath is plated on the cathode when the power source is operated; And metal salts selected from copper, gold, silver, palladium, platinum, cobalt, cadmium, chromium, nickel, bismuth, indium, tin, rhodium, lead, ruthenium, iridium and alloys thereof and additives of formula (1) A device comprising a metal plating bath containing an inhibitory compound: [Formula 1] (R ¹ -NHR ² OH) _n X Where R ¹ and R ² are each independently hydrogen or C ₁ -C ₆ alkyl, n is 1 or 2, when n is 1 and X is _{^{HSO 4 -, H 2 PO 4}} -, NO 3 -, F -, Cl -, Br - or I ^-, and When n is 2, X is SO ₄ ^2- . 41. The apparatus of claim 40, wherein the additive consumption inhibiting compound is included in an amount of about 0.01 to about 20 g / l of the plating bath. 41. The apparatus of claim 40, wherein the metal plating bath further contains a brightening agent, flattening agent, curing agent, wetting agent, malleability improving agent, ductility improving agent, deposition improving agent, inhibitor, or mixtures thereof. 41. The method of claim 40, wherein the anode is an insoluble or soluble anode. 44. The device of claim 43, wherein the insoluble anode comprises cobalt, nickel, ruthenium, rhodium, palladium, iridium, or platinum metal. 45. The apparatus of claim 44, wherein the insoluble anode further comprises titanium, zirconium, hafnium, vanadium, niobium, or tantalum metal. 46. The device of claim 45, wherein the insoluble anode further comprises beryllium, calcium, strontium, barium, scandium, yttrium, lanthanum, or rare earth elements. 44. The apparatus of claim 43, wherein the insoluble anode comprises tantalum coated with iridium dioxide. 41. The apparatus of claim 40, wherein the cathode comprises a printed wiring board, an integrated circuit, an electrical contact surface, a connector, an electrolytic foil, a silicon wafer, a semiconductor, a lead frame, an optoelectronic device, a solder bump, an ornament, a sanitary instrument, and the like.