US20130295294A1 - Electroless copper plating bath and electroless copper plating method - Google Patents

Electroless copper plating bath and electroless copper plating method Download PDF

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US20130295294A1
US20130295294A1 US13/729,721 US201213729721A US2013295294A1 US 20130295294 A1 US20130295294 A1 US 20130295294A1 US 201213729721 A US201213729721 A US 201213729721A US 2013295294 A1 US2013295294 A1 US 2013295294A1
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electroless copper
copper plating
plating bath
plating
concentration
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Takahiro Ishizaki
Tomoharu Nakayama
Teruyuki Hotta
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C Uyemura and Co Ltd
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C Uyemura and Co Ltd
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Assigned to C. UYEMURA & CO., LTD. reassignment C. UYEMURA & CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HOTTA, TERUYUKI, ISHIZAKI, TAKAHIRO, NAKAYAMA, TOMOHARU
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/02—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition
    • C23C18/08—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by thermal decomposition characterised by the deposition of metallic material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1603—Process or apparatus coating on selected surface areas
    • C23C18/1605—Process or apparatus coating on selected surface areas by masking
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C23C18/1635—Composition of the substrate
    • C23C18/1637—Composition of the substrate metallic substrate
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/31—Coating with metals
    • C23C18/38—Coating with copper
    • C23C18/40—Coating with copper using reducing agents
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C23C18/1646—Characteristics of the product obtained
    • C23C18/165—Multilayered product
    • C23C18/1651—Two or more layers only obtained by electroless plating
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1633—Process of electroless plating
    • C23C18/1655—Process features
    • C23C18/166—Process features with two steps starting with addition of reducing agent followed by metal deposition

Definitions

  • the present invention relates to an electroless copper plating bath and an electroless copper plating method, more specifically, an electroless copper plating bath not containing formaldehyde and being usable at approximately neutral pH, and an electroless copper plating method using the electroless copper plating bath.
  • Formaldehyde has been used for a conventional electroless copper plating bath as a reducing agent for copper ions.
  • the vapor pressure of formaldehyde is high, and deterioration of work environment by the irritating odor and harmful effects on the human body due to carcinogenicity have been pointed out.
  • an electroless copper plating bath using formaldehyde is strongly alkaline, whereby a material to be plated is damaged and easily deteriorates, and thus the electroless copper plating bath can not be effectively used, for example, for metal, such as aluminum or aluminum alloy, and the use has been limited.
  • amine borane has a considerably high reducing power, and has a problem that a plating bath is easily decomposed.
  • electroless copper plating bath solution containing amine borane as a reducing agent while having good bath stability and high practicality.
  • the formaldehyde shows a strong reduction power selectively over the surface of metal, such as palladium and copper, while has a weak reducing action in a plating bath, and therefore deposition does not take place easily on a portion other than a pattern (metal).
  • a borane compound such as dimethylamine borane, has a reducing power strong enough to reduce water to hydrogen, thereby reducing metal ions to metal not only on a metal but also in a plating bath, and therefore there has been a problem that the selectivity onto a pattern is low, and accordingly deposition takes place outside a pattern.
  • the present invention is proposed in view of such conventional actual circumstances, and the purpose of the present invention is to provide an electroless copper plating bath and an electroless copper plating method using the electroless copper plating bath, the electroless copper plating bath not containing formaldehyde; being usable under approximately neutral pH conditions; improving plating bath stability; and being capable of forming a plating film with a good thickness while controlling deposition outside a pattern.
  • the present inventors earnestly studied to achieve the above-mentioned purpose, and, as a result, found that, in a formaldehyde-free electroless copper plating bath, controlling the balance of promotion and inhibition of plating deposition enabled deposition outside a pattern to be effectively controlled while enabled a plating film with a good thickness to be formed, and completed the present invention.
  • an electroless copper plating bath is an electroless copper plating bath containing a water-soluble copper salt, and amine borane or a substituted derivative thereof as a reducing agent; not containing formaldehyde; and having a pH of 4 to 9, wherein polyaminopolyphosphonic acid as a complexing agent, an anionic surface-active agent, an antimony compound, and a nitrogen-containing aromatic compound are contained.
  • An electroless copper plating method is characterized in that a copper plating film is formed on a substrate by using the above-mentioned electroless copper plating bath.
  • the electroless copper plating bath can be used under approximately neutral pH conditions, and plating treatment can be performed for a material to be plated without causing damage.
  • plating deposition outside a pattern can be effectively controlled, and a plating film with a good thickness can be formed.
  • plating treatment is performed simply and easily without providing a barrier layer or the like for a base material made of aluminum, aluminum alloy, or the like, and the electroless copper plating bath can be suitably used for manufacturing of semiconductor wafers and the like.
  • FIG. 1 is a graph showing a relationship between an antimony concentration in an electroless copper plating bath and a deposition film thickness.
  • FIG. 2 is a graph showing a relationship between an antimony concentration in an electroless copper plating bath and a deposition film thickness.
  • the electroless copper plating bath according to the present embodiment is an electroless copper plating bath, not containing formaldehyde, that is, what is called a formaldehyde- (formalin-) free plating bath; containing a water-soluble copper salt, and amine borane or a substituted derivative thereof as a reducing agent; and having a pH of 4 to 9.
  • the electroless copper plating bath is characterized in that polyaminopolyphosphonic acid as a complexing agent, an anionic surface active agent, an antimony compound, and a nitrogen-containing aromatic compound are contained.
  • the electroless copper plating bath according to the present embodiment does not contain a reducing agent, such as formaldehyde or glyoxylic acid, which is used under strongly alkaline pH conditions, but contains amine borane or a substituted derivative thereof as a reducing agent, which can be used under neutral to weakly alkaline pH conditions.
  • a reducing agent such as formaldehyde or glyoxylic acid
  • amine borane or a substituted derivative thereof as a reducing agent
  • the electroless copper plating bath according to the present embodiment can be suitably used, for example, as a plating bath to form a plating film for a semiconductor wafer made of aluminum, aluminum alloy, or the like, and can form a good plating film.
  • the electroless copper plating bath according to the present embodiment contains polyaminopolyphosphonic acid as a complexing agent, an anionic surface active agent, an antimony compound, and a nitrogen-containing aromatic compound, as mentioned above, whereby stability of the plating bath can be increased and the balance of promotion and inhibition of plating deposition can be controlled, and, with a higher pattern selectivity, a plating film with a good thickness can be formed.
  • Such electroless copper plating bath can simply and easily form a good plating film having no plating protrusion on a metal base material, such as aluminum or aluminum alloy, or magnesium or magnesium alloy, without providing a barrier layer or the like thereon to prevent deposition outside a pattern, and can be suitably used, for example, in manufacturing of semiconductor wafers.
  • a metal base material such as aluminum or aluminum alloy, or magnesium or magnesium alloy
  • Examples of a water-soluble copper salt include copper sulfate, copper nitrate, copper chloride, copper acetate, copper citrate, copper tartrate, and copper gluconate, and these water-soluble copper salts may be used alone or two or more kinds of these may be mixed at an arbitrary ratio and used.
  • a concentration of the water-soluble copper salt for example, a copper concentration may be 0.005 to 0.5 mol/L, preferably 0.01 to 0.5 mol/L, more preferably 0.05 to 0.1 mol/L.
  • concentration of the water-soluble copper salt is less than 0.005 mol/L, a deposition rate is slower and a plating time is longer, which is not economical.
  • concentration exceeds 0.5 mol/L an amount of pumping increases and a cost rises, and in addition, a plating solution is unstable. Furthermore, nodules and roughness are easily formed and pattern characteristics are lowered.
  • amine borane or a substituted derivative thereof as a reducing agent examples include dimethylamine borane, tert-butylamine borane, triethylamine borane, and trimethylamine borane.
  • Amine borane or a substituted derivative thereof is a reducing agent which is usable at neutral to weakly alkaline pH. Accordingly, amine borane or a substituted derivative thereof is not used for a plating bath having a strongly alkaline pH, such as a plating bath using an aldehyde reducing agent, such as formaldehyde and glyoxylic acid, and therefore damage to a metal base material or the like to be plated is controlled, and deterioration thereof can be prevented. In addition, unlike an aldehyde reducing agent, amine borane or a substituted derivative thereof can exclude deterioration of work environment and harmful effects on the human body, whereby safety can be improved.
  • a concentration of amine borane or a substituted derivative thereof as a reducing agent is preferably 0.01 to 0.5 mol/L.
  • the electroless copper plating bath according to the present embodiment contains polyaminopolyphosphonic acid as a complexing agent.
  • Polyaminopolyphosphonic acid can easily complex copper ions efficiently at approximately neutral pH, and control decomposition of a plating bath and improve the stability.
  • polyaminopolyphosphonic acid examples include N,N,N′,N′-ethylenediaminetetrakis(methylene phosphonic acid), nitrilotris(methylene phosphonic acid), diethylenediamine penta(methylene phosphonic acid), diethylenetriamine penta(methylene phosphonic acid), bis(hexamethylene triamine penta(methylene phosphonic acid)), and glycine N,N-bis(methylene phosphonic acid).
  • a concentration of polyaminopolyphosphonic acid as a complexing agent is not particularly limited, but preferably 0.01 to 1 mol/L.
  • concentration is less than 0.01 mol/L, copper ions cannot fully be complexed and a plating bath could become unstable.
  • concentration exceeds 1 mol/L, an amount of pumping increases and a cost rises.
  • a deposition rate of copper is slower and a plating time is longer, which is not economical.
  • a base film could be damaged and degraded.
  • the electroless copper plating bath according to the present embodiment contains an anionic surface active agent.
  • an anionic surface active agent is made to be contained, stability of a plating bath can be improved.
  • a detailed mechanism which improves stability of a plating bath is not certain, but, it is presumed that, when an anionic surface active agent is added, the anionic surface active agent adsorbs to metal particles produced in a plating bath, thereby inhibiting the particles from further growing, and thus there is an effect that dissolution of the particles by the above-mentioned complexing agent and other additives is promoted. Furthermore, as a factor in improvement of bath stability, it also can be presumed that the dispersion effect by the anionic surface active agent inhibits the metal particles formed in a plating bath from agglomerating and growing.
  • a nonionic surface active agent has lower adsorptivity to metal particles and lower effects in improving bath stability.
  • the electroless copper plating bath has a high salt concentration, whereby a cloud point of a nonionic surface active agent is lowered and turbidity is easily produced.
  • a concentration of a nonionic surface active agent is made high, the nonionic surface active agent has a high foaming property, whereby it becomes difficult to raise the concentration in order to improve bath stability.
  • anionic surface active agent examples include an alkyl carboxylic acid surface active agent; naphthalene sulfonate formaldehyde condensate, such as sodium salt of ⁇ -naphthalenesulfonic acid formalin condensate (for example, DEMOL N manufactured by Kao Corp., and LAVELIN series manufactured by Dai-Ichi Kogyo Seiyaku Co., Ltd.); polyoxy alkylene ether sulfate, such as sodium polyoxyethylene lauryl ether sulfate (for example, EMAL 20C manufactured by Kao Corp.) and polyoxyethylene alkyl ether sulfate triethanolamine (for example, EMAL 20T manufactured by Kao Corp.); higher alcohol sulfuric ester or its salt, such as sodium dodecyl sulfate (for example, EMAL 10G manufactured by Kao triethanolamine dodecyl sulfurate (for example, EMAL TD manufactured by Kao Corp.), and dodecyl
  • a concentration of the anionic surface active agent is not particularly limited, but preferably 0.01 to 2000 mg/L.
  • concentration is less than 0.01 mg/L, an effect as a stabilizer is not fully obtained and a plating bath could become unstable. Furthermore, nodules and roughness are easily formed.
  • concentration exceeds 2000 mg/L, a foaming property is too high. Furthermore, water washability in a downstream process falls, and treatment of waste liquid and waste water becomes difficult.
  • the electroless copper plating bath according to the present embodiment contains an antimony compound.
  • an antimony compound when an antimony compound is added, an effect of promotion of plating deposition by underpotential deposition phenomenon and an effect of deposition inhibition by a catalyst poison effect accompanying adsorption of antimony are balanced, whereby an effect of improvement in deposition rate and an effect of inhibition of plating protrusion can be obtained.
  • the underpotential deposition phenomenon means a phenomenon in which, at the time when an element (antimony) to be added is redissolved as an ion immediately after being reduced, electrons are emitted, whereby deposition of target metal (copper) is promoted, and thus metal deposits at an electric potential lower than a theoretically-calculated deposition potential.
  • Experiment Example 1 a sample was obtained in such manner that, on an Al—Si alloy sputtered film formed on a silicon wafer, a pattern was formed with a TiN film, and then a double zincate treatment was performed in accordance with the usual method, and the sample was immersed in an electroless copper plating bath having the following composition for 1 hour to perform electroless copper plating treatment, whereby a copper plating film was formed on the pattern.
  • Antimony oxide refer to Table 1 below. (as an antimony concentration)
  • a film thickness of the formed plating film, an amount of deposition outside the pattern (a protrusion amount), and plating appearance were examined.
  • Table 1 below shows each measurement result.
  • FIG. 1 shows variations of deposition film thickness with respect to a concentration of antimony in the electroless copper plating bath.
  • “bridge” in the evaluation of plating protrusion represents a state in which patterns are connected each other by plating protrusion
  • occurrence of edge thinning” in the evaluation of appearance represents a phenomenon in which a film thickness of a periphery portion of a substrate/pad is thinner.
  • a minus value of plating protrusion represents a state in which plating does not deposit at a pattern edge portion due to occurrence of edge thinning, whereby the base is exposed.
  • FIG. 2 shows variations of deposition film thickness with respect to a concentration of antimony in the electroless copper plating bath. Note that terms used for the evaluation shown in Table 2 below represent the same as those used in Table 1 above.
  • the inhibition of plating deposition appears at a pattern end portion (edge portion) to which antimony easily adsorbs, while mainly the promotion of plating deposition appears at portions, other than a pattern edge portion, to which antimony hardly adsorbs, whereby a plating film with good thickness is formed while spread (plating protrusion) of plating deposition outside a pattern can be controlled.
  • an effect of improvement in a deposition rate and an effect of inhibition of plating protrusion can be obtained based on the balance between an effect of promotion of plating deposition and an effect of deposition inhibition by an catalyst poison effect accompanying adsorption of antimony, whereby pattern selectivity can be increased, and a plating film with a good film thickness in which plating protrusion is controlled can be formed.
  • a specific amount (concentration) of an antimony compound added is different depending on conditions of other composition components of plating bath (plating composition) and a base, stirring conditions, and the like, thereby being preferably suitably changed in accordance with those conditions, but, for example, may be 0.1 to 20 mg/L, preferably 0.5 to 10 mg/L, more preferably 1 to 4 mg/L.
  • the antimony compound is not limited so far as it is a water-soluble compound which dissolves in a plating bath, and for example, antimony oxide, antimony chloride, and the like may be used.
  • the electroless copper plating bath according to the present embodiment contains a nitrogen-containing aromatic compound.
  • a nitrogen-containing aromatic compound such as example 2,2′-bipyridyl and 1,10-phenanthroline
  • 2,2′-bipyridyl and 1,10-phenanthroline has been used as a stabilizer or an agent to improve film physical-properties, of a plating bath.
  • the nitrogen-containing aromatic compound comes to act as an promoter which promotes metal plating.
  • nitrogen-containing aromatic compound examples include imidazole or a substituted derivative thereof; pyrazole or a substituted derivative thereof; oxazole or a substituted derivative thereof; thiazole or a substituted derivative thereof; pyridine or a substituted derivative thereof; pyrazine or a substituted derivative thereof; pyrimidine or a substituted derivative thereof; pyridazine or a substituted derivative thereof; triazine or a substituted derivative thereof; benzothiophene or a substituted derivative thereof; benzothiazole or a substituted derivative thereof; pyridine or a substituted derivative thereof, such as 2,2′-dipyridyl, 4,4′-dipyridyl, nicotinic acid, nicotinamide, picoline, or lutidine; quinoline or a substituted derivative thereof, such as hydroxyquinoline; acridine or a substituted derivative thereof, such as 3,6-dimethylaminoacridine, prof
  • a concentration of the nitrogen-containing aromatic compound is not limited, but preferably 0.01 to 1000 mg/L.
  • concentration is less than 0.01 mg/L, an effect as a promoter is not obtained, and a deposition rate is slower and a plating time is longer, which is not economical. Furthermore, deposition of copper at an initial stage is poorer, whereby a base material could be damaged and an undeposited portion could be produced.
  • concentration exceeds 1000 mg/L, a deposition rate is too high, so that a rough film is produced. In addition, nodules and roughness are easily formed, and pattern characteristics are lowered. Furthermore, a plating bath could become unstable.
  • the plating bath has a pH of 4.0 to 9.0, preferably a pH of 5.0 to 9.0, more preferably a pH of 6.0 to 8.0.
  • the electroless copper plating bath according to the present embodiment contains, as a reducing agent, amine borane or a substituted derivative thereof, which is usable under neutral to alkaline pH conditions.
  • the electroless copper plating bath can be used in a range of pH 4.0 to pH 9.0, and plating treatment can be performed without giving damage to a base material to be plated.
  • the pH of the plating bath can be adjusted, for example, by making a pH adjustor, such as sodium hydroxide, potassium hydroxide, or tetramethyl ammonium hydroxide, contained.
  • a pH adjustor such as sodium hydroxide, potassium hydroxide, or tetramethyl ammonium hydroxide
  • a temperature of the plating bath is not particularly limited, but 20 to 90 degrees C., preferably 40 to 80 degrees C., more preferably 60 to 70 degrees C.
  • a deposition rate is slower and a plating time is longer, which is not economical.
  • the bath temperature exceeds 90 degrees C., a deposition rate is too high, so that a rough film is produced, and in addition, a warp of a base material sometimes occurs due to heat shrinkage of a film after plating.
  • nodules and roughness are easily formed, and pattern characteristics are lowered.
  • a plating bath could become unstable, and natural consumption of a reducing agent increases, thereby leading to an increase in cost.
  • the electroless copper plating bath according to the present embodiment is an electroless copper plating bath containing amine borane or a substituted derivative thereof as a reducing agent, and not containing formaldehyde, wherein polyaminopolyphosphonic acid as a complexing agent, an anionic surface active agent, an antimony compound, and a nitrogen-containing aromatic compound are contained.
  • This electroless copper plating bath is usable at approximately neutral pH, and therefore, without giving damage to a material to be plated, good plating treatment can be performed, for example, for a material to be plated which easily deteriorates, such as aluminum.
  • the electroless copper plating bath can improve the stability of the plating bath, and also can control the balance between promotion and inhibition of plating deposition, thereby effectively controlling the plating protrusion outside a pattern while not making a thinner edge and the like occur, and a desired plating film with a good thickness can be formed.
  • a good plating film without plating protrusion can be simply and easily formed on aluminum or aluminum alloy, or magnesium or magnesium alloy, without providing a barrier layer or the like to prevent deposition outside a pattern, and the electroless copper plating bath can be suitably used, for example, in manufacturing of semiconductor wafers.
  • a plating film to be formed is smooth, for example, peel strength of wire bonding can be improved. Moreover, the appearance of the plating film is excellent.
  • electroless copper plating method using the above-mentioned electroless copper plating bath will be explained.
  • a well-known method may be used as the electroless copper plating method.
  • catalyst addition treatment or the like is required as pretreatment, a well-known method may be applied as the catalyst addition treatment.
  • a bath temperature of the electroless copper plating bath is controlled to be 20 to 90 degrees C., preferably 40 to 80 degrees C., more preferably 60 to 70 degrees C.
  • Electroless copper plating treatment time is not particularly limited, and may be suitably set so as to obtain a desired film thickness. Specifically, the time may be, for example, approximately 30 seconds to 15 hours.
  • a water-soluble copper salt as a source of copper ions, a reducing agent, a complexing agent, and other additives are supplied into the electroless copper plating solution continuously or periodically to maintain those concentrations in a predetermined concentration range.
  • the electroless copper plating bath is preferably stirred by air bubbling or the like, as needed.
  • the electroless copper plating method using the electroless copper plating bath is such that, for example, without providing a barrier layer, zincate treatment (zinc substitution) is performed for a base material made of aluminum or aluminum alloy, or magnesium or magnesium alloy, and then electroless copper plating treatment is performed using the above-mentioned electroless copper plating bath.
  • zincate treatment zinc substitution
  • electroless copper plating treatment is performed using the above-mentioned electroless copper plating bath.
  • electroless copper plating method is such that activation treatment is performed for a thin film containing copper, nickel, palladium, platinum, tungsten, molybdenum, rhodium, titanium, tantalum, and the like, by substitution for palladium, platinum, copper, and the like, and then, electroless copper plating treatment is performed using the above-mentioned electroless copper plating bath.
  • electroless copper plating method is such that, after the above-mentioned activation treatment, reduction treatment is performed by a treatment solution containing borane or a substituted derivative thereof, and then electroless copper plating treatment is performed using the above-mentioned electroless copper plating bath.
  • Example 1 to Example 2 a film thickness of a plating film and a deposition amount outside a pattern (a plating protrusion amount) were examined by changing the composition of an electroless plating bath.
  • Antimony oxide 2 mg/L as an antimony concentration
  • a sample was obtained in such manner that, on an Al—Si alloy sputtered film formed on a silicon wafer, a pattern was formed with a TiN film, and then double zincate treatment was performed in accordance with the usual method, and the sample was immersed in an electroless copper plating bath having the above-mentioned composition for 1 hour to perform electroless copper plating treatment, whereby a copper plating film was formed on the pattern.
  • the formed plating film difference in height between before and after the plating treatment was measured with a laser microscope to measure a plating film thickness. As a result, it was found that the formed plating film had a good film thickness, namely a film thickness of 5.3 ⁇ m, and there was almost no plating protrusion outside the pattern, namely 5 ⁇ m of plating protrusion.
  • Antimony oxide 2 mg/L as an antimony concentration
  • a sample was obtained in such manner that, on an Al—Si alloy sputtered film formed on a silicon wafer, a pattern was formed with a TiN film, and then double zincate treatment was performed in accordance with the usual method, and the sample was immersed in an electroless copper plating bath having the above-mentioned composition for 1 hour to perform electroless copper plating treatment, whereby a copper plating film was formed on the pattern.
  • the formed plating film difference in height between before and after the plating treatment was measured with a laser microscope to measure a plating film thickness. As a result, it was found that the formed plating film had a good film thickness, namely a film thickness of 5.3 ⁇ m, and there was almost no plating protrusion outside the pattern, namely 5 ⁇ m of plating protrusion.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that an antimony compound was not contained in the composition of the electroless copper plating bath.
  • the formed plating film had a thickness of 2.6 ⁇ m and was thinner than those of Examples 1 and 2, and an amount of plating protrusion outside the pattern was 15 ⁇ m.
  • plating deposition was inhibited while a large amount of protruding deposition was produced, and accordingly pattern selectivity was very low.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that 2 mg/L of lead was added in place of 2 mg/L of antimony in the composition of the electroless copper plating bath.
  • the formed plating film had a thickness of 2.2 ⁇ m and was thinner than those of Examples 1 and 2, and an amount of plating protrusion outside the pattern was 12 ⁇ m.
  • plating deposition was inhibited while a large amount of protruding deposition was produced, and accordingly pattern selectivity was very low.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that 0.3 mg/L of thallium was added in place of 2 mg/L of antimony in the composition of the electroless copper plating bath.
  • the formed plating film had a thickness of 1.8 ⁇ m and was considerably thinner than those of Examples 1 and 2.
  • there was a large amount of plating protrusion outside the pattern and the plating protrusion caused a connection between patterns (bridge), and therefore the amount of the plating protrusion could not be measured.
  • plating deposition was inhibited while a large amount of protruding deposition was produced, and accordingly pattern selectivity was very low.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that sodium lauryl sulfate was not contained in the composition of the electroless copper plating bath.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that o-phenanthroline was not contained in the composition of the electroless copper plating bath.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that 0.5 g/L of polyethylene glycol (PEG) #1000 was added in place of 20 mg/L of sodium lauryl sulfate in the composition of the electroless copper plating bath.
  • PEG polyethylene glycol
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that 2 mg/L of bismuth was added in place of 2 mg/L of antimony in the composition of the electroless copper plating bath.
  • the formed plating film had a good film thickness, namely a film thickness of 4.4 ⁇ m, but, due to plating protrusion outside the pattern, a connection between patterns (bridge) was produced, and therefore an amount of the plating protrusion could not be measured.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that 0.08 ml/L of diethylene triamine pentaacetic acid was added in place of 0.08 mol/L of ethylene diamine tetra(methylene phosphonic acid) in the composition of the electroless copper plating bath.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that an electroless copper plating bath having the following composition was used.
  • Electroless copper plating treatment was performed to form a copper plating film on a pattern in the same manner as in Example 1, except that an electroless copper plating bath having the following composition was used.
  • Comparative Example 10 the Al—Si alloy sputtered film dissolved, whereby the plating treatment was not performed properly. This is considered because the plating bath contained glyoxylic acid as a reducing agent, which was highly alkaline, as is the case with formaldehyde, thereby causing serious damage to a base material.

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CN105648426A (zh) * 2016-03-23 2016-06-08 深圳市松柏实业发展有限公司 沉铜组合液
CN108336473A (zh) * 2018-02-06 2018-07-27 北京宏诚创新科技有限公司 铜-铝纳米接面常温制程方法
US10450666B2 (en) 2016-03-18 2019-10-22 C. Uyemura & Co., Ltd. Copper plating solution and copper plating method
CN115440989A (zh) * 2022-09-30 2022-12-06 楚能新能源股份有限公司 一种锂离子电池用负极集流体、极片及其制备方法

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PT3497267T (pt) * 2016-08-15 2020-07-28 Atotech Deutschland Gmbh Composição aquosa acídica para galvanização eletrolítica de cobre
DE112020001854T5 (de) * 2019-04-10 2022-01-05 Mitsubishi Electric Corporation Halbleiterbauelement und Verfahren zu dessen Herstellung
JP7111410B1 (ja) * 2020-11-10 2022-08-02 メルテックス株式会社 無電解銅めっき液
CN113463074B (zh) * 2021-06-03 2022-06-14 广东硕成科技股份有限公司 一种沉铜组合物及沉铜方法

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GB1425298A (en) * 1973-04-04 1976-02-18 Philips Electronic Associated Electroless deposition of copper
US4143186A (en) * 1976-09-20 1979-03-06 Amp Incorporated Process for electroless copper deposition from an acidic bath
USH325H (en) * 1980-07-30 1987-09-01 Richardson Chemical Company Electroless deposition of transition metals
US4374009A (en) * 1981-09-28 1983-02-15 Xerox Corporation Electrochemical post treatment of perpendicular magnetic recording media
US20040201946A1 (en) * 2003-03-10 2004-10-14 Tadashi Iwamatsu Ion generating apparatus, air conditioning apparatus, and charging apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10450666B2 (en) 2016-03-18 2019-10-22 C. Uyemura & Co., Ltd. Copper plating solution and copper plating method
CN105648426A (zh) * 2016-03-23 2016-06-08 深圳市松柏实业发展有限公司 沉铜组合液
CN108336473A (zh) * 2018-02-06 2018-07-27 北京宏诚创新科技有限公司 铜-铝纳米接面常温制程方法
CN115440989A (zh) * 2022-09-30 2022-12-06 楚能新能源股份有限公司 一种锂离子电池用负极集流体、极片及其制备方法

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CN103388138A (zh) 2013-11-13

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