EP3922753A1 - Stromlose nickel- oder kobaltplattierungslösung - Google Patents

Stromlose nickel- oder kobaltplattierungslösung Download PDF

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Publication number
EP3922753A1
EP3922753A1 EP20179312.2A EP20179312A EP3922753A1 EP 3922753 A1 EP3922753 A1 EP 3922753A1 EP 20179312 A EP20179312 A EP 20179312A EP 3922753 A1 EP3922753 A1 EP 3922753A1
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EP
European Patent Office
Prior art keywords
plating solution
cobalt
nickel
layer
ions
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20179312.2A
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English (en)
French (fr)
Inventor
Kadir TUNA
Thiago Pugliesi Garcia
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Atotech Deutschland GmbH and Co KG
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Atotech Deutschland GmbH and Co KG
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Application filed by Atotech Deutschland GmbH and Co KG filed Critical Atotech Deutschland GmbH and Co KG
Priority to EP20179312.2A priority Critical patent/EP3922753A1/de
Priority to TW110121157A priority patent/TW202204690A/zh
Priority to JP2022576217A priority patent/JP2023529933A/ja
Priority to CN202180047811.5A priority patent/CN115836142A/zh
Priority to PCT/EP2021/065564 priority patent/WO2021250146A1/en
Priority to KR1020237000473A priority patent/KR20230022959A/ko
Priority to US18/001,346 priority patent/US20230235462A1/en
Publication of EP3922753A1 publication Critical patent/EP3922753A1/de
Pending legal-status Critical Current

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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
    • C23C18/16—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
    • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
    • C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron 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
    • C23C18/1675—Process conditions
    • C23C18/168—Control of temperature, e.g. temperature of bath, substrate

Definitions

  • the present invention relates to an electroless nickel or cobalt plating solution, a method for electroless plating of a nickel or cobalt deposit, preferably a layer, on a substrate, and a respective electronic article comprising such a deposit and layer, respectively.
  • Nickel and cobalt layers are widely used in electronic devices. Such layers and methods for producing them are known from the prior art. Nickel and cobalt layers are often used as barrier layers, to separate a copper layer from a tin layer or a gold layer. Migration of copper into the tin layer or gold layer is prevented by such a barrier layer which is located in between these layers.
  • US 2015/0307993 A1 discloses a solution for electroless deposition of cobalt, comprising a reducing agent of Ti 3+ ions and Co 2+ ions. Pure cobalt layers are obtained and the solution is free of phosphorus-containing compounds.
  • Nakao et al., Surface and Coatings Technology, 169-170 (2003) 132-134 disclose a pure nickel film containing no phosphorus which was obtained from an electroless plating solution.
  • the solution uses a titanium ion redox system.
  • Two kinds of complexing agent were used, nitriloacetic acid and citric acid.
  • US 2012/0104331 A1 discloses a deposition solution to deposit metals and metal alloys such as for fabrication of electronic devices.
  • the deposition solution comprises metal ions and a pH adjustor.
  • the pH adjustor comprises a functional group having a general formula (R 1 R 2 N)(R 3 R 4 N)C-N-R 5 where: N is nitrogen; C is carbon; and R 1 , R 2 , R 3 , R 4 , and R 5 are the same or different and represent hydrogen, alkyl group, aryl group, or alkylaryl group.
  • Possible metals to be deposited are nickel or cobalt.
  • An objective of the present invention was to provide an electroless plating solution and a respective plating method which are suitable to produce highly pure nickel or cobalt layers. It was furthermore an objective to deposit cobalt and nickel, respectively, selectively on a metal without simultaneous metal plating on a non-conductive material, in particular selectively on copper without further activation of said copper. Furthermore, an increased/high deposition rate and increased stability of the electroless plating solution are desired.
  • the present invention provides an electroless nickel or cobalt plating solution, a method for electroless plating, and an electronic article according to the independent claims and solves at least one, preferably all of above mentioned objectives. Further embodiments are disclosed in dependent claims and this description.
  • the present invention provides an electroless nickel or cobalt plating solution, comprising
  • the invention also provides a method for electroless plating of a nickel or a cobalt deposit on a substrate, the method comprising contacting the substrate with the electroless plating solution according to the present invention such that the nickel or cobalt deposit is electrolessly plated on the substrate.
  • the invention also provides an electronic article, comprising a nickel layer or a cobalt layer, wherein the nickel or the cobalt layer is obtainable or obtained from an electroless plating solution of the present invention, or obtained according to a method of the present invention, wherein the nickel layer or the cobalt layer comprises 99 wt% or more nickel or cobalt, based on the total weight of the nickel layer or the cobalt layer, wherein the article comprises a copper layer, and wherein the nickel layer or the cobalt layer is disposed on the copper layer.
  • a layer is in this description named after a metal, like a gold layer, a tin layer, a nickel layer or a cobalt layer, this term also encompasses alloys comprising the respective metal as main component, if not otherwise mentioned.
  • the plating solution of the present invention is a nickel plating solution or a cobalt plating solution. Most preferably, if the plating solution of the present invention is a nickel plating solution, the plating solution does not comprise cobalt ions. If the plating solution of the present invention is a cobalt plating solution, the plating solution most preferably does not comprise nickel ions. This means that the present invention is in one aspect directed to a nickel plating solution only, and in another aspect directed to a cobalt plating solution only.
  • Ni 2+ ions comprise Ni 2+ ions, preferably are (only) Ni 2+ ions.
  • cobalt ions comprise Co 2+ ions, preferably are (only) Co 2+ ions.
  • nickel or cobalt is the main metal component in the solution, most preferably the only ones to be deposited. If one or more further metals to be reduced and co-deposited are present, nickel or cobalt, respectively, preferably constitute 95 mol% or more of all metals to be reduced and deposited in the plating solution. Titanium as reducing agent is excluded from this consideration.
  • no transition metals other than cobalt or nickel are present, except titanium as reducing agent, more preferably, no metals other than cobalt or nickel, except titanium as reducing agent, except lead, and except an alkaline and/or an alkaline earth metal are present.
  • the plating solution is a nickel plating solution.
  • the plating solution is a cobalt plating solution, the solution preferably does not comprise lead.
  • the plating solution of the present invention typically does not comprise tungsten, more preferably the plating solution of the present invention typically does not comprise antimony, arsenic, cadmium, chromium, copper, gold, indium, iridium, iron, manganese, molybdenum, osmium, palladium, platinum, rhodium, ruthenium, silver, tungsten, zinc, or mixtures thereof.
  • the plating solution of the present invention does not comprise tin.
  • the plating solution of the present invention is not an electroless nickel alloy plating solution or an electroless cobalt alloy plating solution.
  • a plating solution of the present invention is preferred, wherein the plating solution comprises iron ions and/or molybdenum ions to be reduced and co-deposited with nickel and cobalt, respectively.
  • Ti 3+ ions are used as a reducing agent for reducing the cobalt ions and nickel ions.
  • the plating solution of the present invention preferably additionally comprises Ti 4+ ions, wherein the Ti 4+ ions are present in a lower amount than the Ti 3+ ions.
  • the Ti 3+ ions are produced according to a method disclosed in WO 2013/182478 A2 , which is incorporated by reference in its entirety in this disclosure.
  • WO 2013/182478 A2 discloses a regeneration device which is preferably used to reduce Ti 4+ ions to Ti 3+ ions.
  • the plating solution of the present invention preferably does not comprise any further reducing agent than titanium ions.
  • the plating solution of the present invention does not comprise any reducing agent selected from the following group of compounds or classes of compounds:
  • the nickel or cobalt plating solution according to the present invention thus comprises at least one accelerator selected from the group consisting of sulfites, dithionites, thiosulfates, tetrathionates, polythionates, disulfites, sulfides, disulfide, polysulfide, elemental sulfur and mixtures thereof.
  • the at least one accelerator is inorganic. If two or more accelerators are selected they preferably are all inorganic.
  • Preferable sources of sulfites, dithionites, thiosulfates, tetrathionates, polythionates, sulfide, disulfide, polysulfide and disulfites are the respective salts such as alkaline salts (e.g. sodium sulfite, potassium sulfite, sodium bisulfite), earth alkaline metal salts (e.g. magnesium sulfite, calcium sulfite), ammonium salts and mixtures of the aforementioned.
  • the at least one accelerator is water soluble and the used counter ions as sodium or potassium will not co-deposited.
  • Dithionites, thiosulfates, tetrathionates, polythionates, disulfites, disulfide, polysulfide, and elemental sulfur are compounds containing at least one S-S moiety.
  • a nickel or cobalt plating solution according to the present invention is preferred, wherein the accelerator(s) is/are selected from the group consisting of alkaline metal sulfites, alkaline metal hydrogen sulfites, alkaline earth metal sulfites, alkaline earth metal hydrogen sulfites, ammonium sulfite, ammonium hydrogen sulfite, alkaline metal dithionites, alkaline metal hydrogen dithionites, alkaline earth met-al dithionites, alkaline earth metal hydrogen dithionites, alkaline metal thiosulfates, alkaline metal hydrogen thiosulfates, alkaline earth metal thiosulfates, alkaline earth metal hydrogen thiosulfates, ammonium thiosulfate, ammonium hydrogen thiosulfate, alkaline metal tetrathionates, alkaline metal hydrogen tetrathionates, alkaline earth metal tetrathionates
  • a nickel or cobalt plating solution according to the present invention is further preferred, wherein the accelerator(s) is/are selected from the group consisting of sodium sulfite, potassium sulfite, sodium hydrogen sulfite (sodium bisulfite), potassium hydrogen sulfite (potassium bisulfite), calcium dihydrogen disulfit (calcium bisulfite), magnesium dihydrogen disulfit (magnesium bisulfite), ammonium sulfite, ammonium hydrogen sulfite, sodium dithionite, potassium dithionite, calcium dithionite, magnesium dithionite, sodium thiosulfate, sodium hydrogen thiosulfate, potassium thiosulfate, calcium thiosulfate, potassium thiosulfate, barium thiosulfate, ammonium thiosulfate, ammonium hydrogen thiosulfate, sodium tetrathionate, potassium tetrathionate, ammoni
  • the at least one pH adjuster is selected from the group consisting of ammonia or an inorganic ammonia derivate as ammonium hydroxide, ammonium chloride.
  • Sodium dithionite and/or sodium sulfite and/or sodium thiosulfate and/or sodium tetrathionate and/or sodium polythionate and/or sodium disulfite are used particularly preferably according to the invention.
  • sulfur in its cyclo-Ss configuration is used.
  • the sulfur is present as sulfur particles, especially sulfur particles with an aerodynamic diameter determined via an aerodynamic particle sizer (APS) below 300 nm, preferably below 200 nm, more preferably below 100 nm.
  • APS aerodynamic particle sizer
  • the at least one accelerator is organic.
  • a preferred organic accelerator is thioacetamide.
  • the molar ratio of all the accelerators used according to the present invention to the nickel ions or cobalt ions is at least 1 to 300. More preferably, the molar ratio of all accelerators used according to the present invention to the nickel ions or cobalt ions ranges from 1 : 200 to 1 : 5.000, even more preferably from 1 : 300 to 1 : 4.000, still even more preferably 1 : 500 to 1 : 1.500, most preferably from 1 : 550 to 1 : 1.000.
  • the total concentration of sulfites, dithionites, thiosulfates, tetrathionates, polythionates, disulfites, sulfides, disulfide, polysulfide and sulfur in the inventive electroless nickel or cobalt plating solution preferably ranges from 0.0008 to 0.80 mmol/L, more preferably from 0.008 to 0.40 mmol/L and even more preferably from 0.04 to 0.16 mmol/L.
  • the total amount by weight of the accelerator(s) in the nickel or cobalt plating solution ranges from 0.01 to 300 ppm, preferably from 0.1 to 200 ppm, and more preferably from 0.5 to 175 ppm.
  • the inventive nickel or cobalt plating solution is free of organic sulfites.
  • the inventors have found that these compounds occasionally have a negative influence on the plating rate and increase the loss of plating rate over time and during use of a nickel or cobalt plating solution containing such organic sulfites.
  • An electroless nickel or cobalt plating solution according to the invention comprising nickel sulfate (hexahydrate) (or cobalt(II) chloride (hexahydrate), respectively), titanium (III) chloride and at least one accelerator selected from the group consisting of sodium sulfite, sodium dithionite, sodium thiosulfate, ammonium sulfide and mixtures thereof.
  • the plating solution of the present invention comprises one or more than one complexing agent independently selected from the group consisting of
  • the plating solution of the present invention comprises one or more than one complexing agent independently selected from the group consisting of
  • An organic phosphonic acid compound is a compound comprising at least one (preferably more than one, more preferably two or more) ⁇ C-PO(OH) 2 group.
  • a salt or an ester thereof is also called a "phosphonate".
  • an ester in the context of the present invention comprises the structure ⁇ C-PO(OR) 2 , wherein R is preferably an organic residue, more preferably independently alkyl or aryl.
  • a phosphonate moiety in the context of the present invention includes above mentioned ⁇ C-PO(OH) 2 group, salts and esters thereof.
  • Such compounds are in particular beneficial in the plating solution of the present invention because they provide a strong complexation and stabilization, which prevents outplating and precipitation, even provided in comparatively low concentrations.
  • These compounds are thermally stable, which is a great advantage over e.g. pyrophosphate, which decomposes under heat faster than said organic phosphonic acid compound, its salts and esters, most preferably than said organic phosphonic acid compound and its salts.
  • HEDP 1-Hydroxyethane 1,1-diphosphonic acid
  • ATMP Aminotris(methylenephosphonic acid)
  • DTPMP Diethylenetriamine penta(methylene phosphonic acid)
  • ETMP Ethylenediamine tetra(methylenephosphonic
  • PBTC Phosphonobutane tricarboxylic acid
  • HDTMP Hexanediamine tetra(methylenephosphonic acid)
  • HEMPA Hydroxyethylamino di(methylenephosphonic acid)
  • BHMTMP Bis(hexamethylene) triamine-pentakis(methylphosphonic acid)
  • the plating solution of the present invention preferably comprises an organic polyphosphoric acid compound, its salts and/or esters, and/or an inorganic polyphosphoric acid compound, its salts and/or esters.
  • a polyphosphoric acid compound is characterized by having a moiety comprising a phosphorous-oxygen-phosphorous arrangement, each phosphorous atom belonging to a phospho-building unit.
  • the inorganic polyphosphoric acid compound preferably comprises, more preferably is, a diphosphoric acid (also called pyrophosphoric acid), a tri- phosphoric acid, a tetra phosphoric acid, or even a higher phosphoric acid.
  • a preferred salt of an inorganic polyphosphoric acid compound is di-phosphate (also called pyrophosphate), tri-phosphate, and tetra-phosphate, most preferred is pyrophosphate. In only rare cases, higher polyphosphates are employed in the plating solution of the present invention.
  • a plating solution of the present invention is preferred with the proviso that the plating solution does not comprise pyrophosphate (preferably pyrophosphate and pyrophosphonic acid), preferably does not comprise pyrophosphate (preferably pyrophosphate and pyrophosphonic acid) but one or more than one complexing agent independently selected from the group consisting of an organic phosphonic acid compound, its salts and esters.
  • pyrophosphate preferably pyrophosphate and pyrophosphonic acid
  • one or more than one complexing agent independently selected from the group consisting of an organic phosphonic acid compound, its salts and esters is in some cases preferred because pyrophosphate shows some instability over time under elevated temperatures. This is not observed with said organic phosphonic acid compound, its salts and esters, preferably not with said organic phosphonic acid compound and its salts.
  • An ester of an inorganic polyphosphoric acid compound is preferably selected from the group consisting of diphosphate ester and triphosphate ester.
  • a non-limiting preferred example is a compound having the formula R-O-([(PO 2 )-O-] n PO 3 )( 2+n ) - , wherein n is an integer and wherein R is an organic moiety, preferably alkyl or aryl. For example, if n is 1, the formula is R-O-((PO 2 )-O-PO 3 ) 3- .
  • a plating solution of the present invention is preferred, wherein the plating solution only comprises phosphorous-containing complexing agents, including the complexing agents as defined above for the plating solution of the present invention, preferably comprises only phosphorous-containing complexing agents as defined for the plating solution of the present invention.
  • the plating solution of the present invention more preferably does not comprise any other complexing agent than mentioned before.
  • a plating solution of the present invention wherein the one or more than one complexing agent is independently only selected from the group consisting of
  • the plating solution of the present invention does not comprise phosphonic acid (H 3 PO 3 ), preferably does not comprise phosphonic acid (H 3 PO 3 ) and pyrophosphonic acid.
  • a molar ratio of the complexing agent to the Ti 3+ ions is 1.5 : 1 or higher, preferably 1.7 : 1 or higher, most preferably is in a range from 1.9 : 1 to 3 : 1.
  • Another preferred upper limit is 20 : 1, more preferably 16 : 1, most preferably 14 : 1, most preferably if the one or more than one complexing agent independently is only selected from the group consisting of an inorganic polyphosphoric acid compound, its salts and esters, even most preferably is pyrophosphate.
  • a plating solution of the present invention wherein a molar ratio of the complexing agent to the Ti 3+ ions is 1.5 : 1 or higher, preferably 1.7 : 1 or higher, most preferably is in a range from 1.9 : 1 to 3 : 1, and the one or more than one complexing agent independently selected from the group consisting of an organic phosphonic acid compound, its salts and esters is the only complexing agent in the plating solution of the present invention.
  • a molar ratio is in particular preferred because the Ti 3+ ions are sufficiently stabilized against oxidation, e.g. by ambient air although the molar ratio is comparatively low. This furthermore stabilizes the entire plating solution of the present invention.
  • a plating solution of the present invention is preferred, wherein the molar ratio of the complexing agent to the Ti 3+ ions is 5 : 1 or higher, preferably 8 : 1 or higher, most preferably is in a range from 10 : 1 to 14 : 1, and the one or more than one complexing agent independently selected from the group consisting of an inorganic polyphosphoric acid compound, its salts and esters is the only complexing agent in the plating solution of the present invention.
  • a plating solution of the present invention wherein a molar ratio of the nickel ions or the cobalt ions to the Ti 3+ ions is in a range from 1 : 3 - 5 : 1, preferably in a range from 1 : 2.5 - 4 : 1, more preferably in a range from 1 : 2 - 3 : 1, even more preferably in a range from 1 : 2 to 2 : 1.
  • a plating solution of the present invention wherein a molar ratio of complexing agent, a complexing agent preferably as described above as being preferred, to nickel ions or cobalt ions is 3 : 1 or higher, preferably is 4 : 1 or higher, more preferably is in a range from 4 : 1 - 7 : 1, more preferably is in a range from 4 : 1 - 6 : 1. In some cases a preferred upper limit is 10 : 1.
  • the aforementioned molar ratios ensure that the nickel and cobalt ions, respectively, are sufficiently complexed to avoid outplating, most preferably at elevated temperatures as preferably used in the method of the present invention (see text below). Furthermore, these molar ranges provide a very good shelf-life of the plating solution of the present invention.
  • a plating solution of the present invention is preferred, wherein a molar ratio of the one or more than one complexing agent independently selected from the group consisting of an organic phosphonic acid compound, its salts and esters to nickel ions or cobalt ions is in a range from 4 : 1 to 5 : 1, with the proviso that said complexing agent is the only complexing agent in the plating solution of the present invention.
  • a concentration of the nickel ions or the cobalt ions in a range from 0.01 - 0.3 mol/L, preferably in a range from 0.015 - 0.2 mol/L, more preferably in a range from 0.02 - 0.1 mol/L, even more preferably in a range from 0.025 - 0.05 mol/L. If the concentration is in the range from 0.01 - 0.3 mol/L an outplating is typically fully avoided, even under elevated temperatures. An excellent stability of the plating solution is obtained if the concentration is in the above mentioned preferred ranges, even over a long plating time.
  • a concentration of the Ti 3+ ions in a range from 0.03 - 0.2 mol/L, preferably in a range from 0.03 - 0.1 mol/L. If the concentration is significantly below 0.03 mol/L in a number of cases an insufficient/incomplete plating is observed. However, if the concentration is significantly above 0.2 mol/L in some cases an undesired instability of the plating solution is observed.
  • a concentration of the one or more than one complexing agent in a range from 0.03 - 2.0 mol/L, preferably in a range from 0.05 - 1.5 mol/L, more preferably in a range from 0.08 - 1.1 mol/L.
  • the concentration is preferably the total concentration.
  • An optimal stability of the plating solution of the present invention is achieved if the concentration is within the above mentioned concentration ranges, in particular within the preferred concentration ranges.
  • a sufficient amount of complexing agent is provided for complexing the nickel or cobalt ions and for stabilizing the Ti 3+ ions. This advantageously means that with the same complexing agent the metal to be plated and the reducing agent can be stabilized. This is a great advantage of the plating solution of the present invention. It furthermore reduces the number of different compounds in the plating solution and alleviated the replenishment of complexing agent. This also applies to the following preferred concentrations.
  • a concentration of the complexing agent is in a range from 0.03 - 1.0 mol/L, preferably in a range from 0.05 - 0.8 mol/L, more preferably in a range from 0.08 - 0.5 mol/L, even more preferably in a range from 0.1 - 0.3 mol/L, most preferably in a range from 0.1 - 0.2 mol/L.
  • a concentration of all complexing agents independently selected from the group consisting of an organic phosphonic acid compound (preferably as described above as being preferred), its salts and esters, is in a range from 0.03 - 1.0 mol/L, preferably in a range from 0.05 - 0.8 mol/L, more preferably in a range from 0.08 - 0.5 mol/L, even more preferably in a range from 0.1 - 0.3 mol/L, most preferably in a range from 0.1 - 0.2 mol/L.
  • a concentration of all complexing agents independently selected from the group consisting of an organic phosphonic acid compound (preferably as described above as being preferred), its salts and esters is in a range from 0.03 - 1.0 mol/L, preferably in a range from 0.05 - 0.8 mol/L, more preferably in a range from 0.08 - 0.5 mol/L, even more preferably in a range from 0.1 - 0.3 mol/L, most preferably in a range from
  • the plating solution of the present invention comprises a liquid solvent.
  • the solution of the invention is preferably water based, i.e. an aqueous plating solution. This means that more than 50 vol% of the liquid solvent is water, preferably 70 vol% or more, more preferably 80 vol% or more, even more preferably 90 vol% or more. Most preferably, water is the only liquid solvent.
  • the plating solution of the present invention preferably consist of
  • the compounds listed in the aforementioned list are preferably generally utilized in the plating solution of the present invention, irrespective of whether the plating solution of the present invention is defined by "comprising" or “consisting of”.
  • the plating solution of the present invention further comprises lead ions, most preferably if the plating solution comprises nickel ions, i.e. the plating solution is a nickel plating solution.
  • Lead ions typically act as a stabilizer in a nickel plating solution. Preferred is a concentration of lead ions in a range from 0.5 - 10 ⁇ mol/L, preferably in a range from 0.1 to 8 ⁇ mol/L.
  • the plating solution of the present invention has a pH value of from 5 to 10.5.
  • Preferred is a plating solution of the present invention, having a pH in a range from 4.0 - 9.5, preferably in a range from 5.0 - 9.0, more preferably in a range from 5.7 - 8.5, even more preferably in a range from 6.4 - 8.2.
  • the method of the present invention is for electroless plating of a nickel or cobalt deposit on a substrate.
  • any plating solution of the invention which is disclosed in this description, is preferably used.
  • the nickel or cobalt deposit obtained by the method of the present invention is substantially free of phosphorous, preferably does not comprise phosphorous.
  • a preferred substrate which is used in the method of the present invention, is an electronic article, a part, or a pre-product thereof or is a substrate finally resulting in an electronic article, a part, or a product thereof.
  • a more preferred substrate is, without limitation: a wafer, a diced and/or further processed wafer, a printed circuit board, an integrated circuit package, parts, or pre-products thereof.
  • the substrate preferably comprises a resin, plastic, ceramic, glass, and/or a metal, preferably comprises at least a metal, more preferably comprises a combination of at least a metal and a non-conductive material.
  • a preferred metal is coper, titanium, titanium alloys (preferably titanium nitride), cobalt, and cobalt alloys, preferably the metal is in a patterned condition, most preferably the metal is a patterned layer.
  • patterned includes structured, i.e. the metal preferably has a three dimensional surface. Thus in some cases it is preferred that the metal is patterned, wherein in other cases the metal is a uniform layer; preferred is in some cases a patterned metal.
  • a preferred non-conductive material is a resin, plastic, ceramic, glass, and/or a silicon-containing material.
  • a method of the present invention is preferred, wherein the cobalt deposit and the nickel deposit, respectively, (preferably the cobalt deposit) is electrolessly plated on cobalt and alloys thereof, preferably on cobalt and alloys thereof in a recessed structure in order to partially or completely fill the recessed structure.
  • the cobalt and alloys thereof prior to the method of the present invention is deposited by physical methods, preferably by sputtering.
  • a very preferred metal is a stack of metals, comprising titanium or titanium alloys (preferably titanium nitride) followed by cobalt and alloys thereof (preferably cobalt), most preferably in a recessed structure.
  • Plating on cobalt, preferably filling, by means of the method of the present invention is in particular beneficial if the recessed structures are small, preferably having an opening width of 20 nm or below, preferably of 10 nm or below.
  • the electroless plating solution has a temperature in a range from 30 - 80°C, preferably in a range from 50 - 75°C, more preferably in a range from 55 - 70°C.
  • This temperature is the temperature of the plating solution of the present invention, which is significantly high. This comparatively high temperature allows a high deposition rate without compromising stability of the plating solution, e.g. by means of outplating and/or precipitation.
  • the cobalt deposit preferably the cobalt layer
  • the nickel deposit preferably the nickel layer
  • a deposition rate in a range from 100 nm/h to 400 nm/h, preferably in a range from 150 nm/h to 380 nm/h, more preferably in a range from 200 nm/h to 360 nm/h, even more preferably in a range from 250 nm/h to 340 nm/h, most preferably in a range from 280 nm/h to 320 nm/h.
  • the nickel or cobalt deposit is a nickel or cobalt layer.
  • a method of the present invention for electroless plating of a nickel or a cobalt layer on a substrate comprising contacting the substrate with the electroless plating solution according to the present invention such that the nickel or cobalt layer is electrolessly plated on the substrate.
  • the nickel or cobalt deposit is a layer.
  • the nickel or cobalt deposit is preferably used for filling structures.
  • the method of the present invention is preferably used to deposit a cobalt or nickel barrier, preferably a layer thereof, on a metal, preferably on copper.
  • the substrate comprises a copper layer, preferably a patterned copper layer, wherein the nickel deposit, preferably the nickel layer, or the cobalt deposit, preferably the cobalt layer, is plated on the copper layer, preferably the nickel deposit, preferably the nickel layer, or the cobalt deposit, preferably the cobalt layer, is plated directly on the copper layer.
  • the substrate comprises a metal, preferably copper
  • the nickel or cobalt deposit preferably the nickel or cobalt layer
  • the substrate comprises a metal, preferably copper
  • the nickel or cobalt deposit preferably the nickel or cobalt layer
  • a plated substrate which preferably comprises the following layers: Cu layer / Ni or Co layer, wherein the Ni or Co layer is preferably an outer layer, i.e. comprising a free, accessible surface.
  • a barrier layer typically prevents copper migration into a further metal layer.
  • a nickel layer is preferably used to prevent migration into a tin layer.
  • a cobalt layer is preferably used to prevent copper migration into a gold layer.
  • the method of the present invention preferably further comprises the step plating a gold layer or a tin layer on the nickel layer or on the cobalt layer, more preferably a gold layer on the cobalt layer, or alternatively a tin layer on the nickel layer.
  • the plated substrate preferably comprises the following layers, in this order: Cu layer / Ni or Co layer / Sn or Au layer, wherein the Sn and the Au layer is preferably an outer layer, i.e. comprising a free, accessible surface.
  • Such a layer structure is also called a "stack" of layers, comprising the mentioned layers in the mentioned order.
  • the Ni or Co layer separates the Cu layer from the respective Sn and Au layer.
  • the above mentioned layers preferably extend over a whole surface or preferably extend over a part of a surface.
  • the copper layer extends over only a part of a surface, i.e. is structured or patterned. In other cases it is preferred that the copper layer extends over a whole surface of the substrate.
  • the nickel or cobalt layer extends over only a part of the copper layer, i.e. is structured or patterned; preferably corresponding at least partly to the structured/patterned copper layer. In other cases it is preferred that the nickel or cobalt layer extends over the entire copper layer.
  • the Sn or Au layer preferably extends over a part of the nickel or cobalt layer. In other cases it is preferred that the nickel or cobalt layer extends over the entire nickel or cobalt layer.
  • the plating method of the present invention comprises the following redox reaction: Ni 2+ + 2Ti 3+ ⁇ Ni 0 + 2Ti 4+ and, respectively, Co 2+ + 2Ti 3+ ⁇ Co 0 + 2Ti 4+
  • the concentration of the Ti 3+ ions decreases because of their oxidation to Ti 4+ ions. Furthermore, the concentration of nickel ions and cobalt ions decreases because they are reduced and plated as a metallic deposit on the substrate.
  • Regeneration is preferably done according to a method as described in WO 2013/182478 A2 , which is incorporated by reference in its entirety.
  • the present text furthermore refers to an electronic article (1), comprising a nickel layer or a cobalt layer (4), wherein the nickel layer or the cobalt layer (4) is obtainable or obtained from an electroless plating solution according to the present invention, or is obtained according to the method of the present invention, wherein the nickel layer (4) or the cobalt layer (4) comprises 99 wt% or more nickel or cobalt, based on the total weight of the nickel layer (4) or the cobalt layer (4), wherein the article comprises a copper layer (3), and wherein the nickel layer or the cobalt layer (4) is disposed on the copper layer.
  • the present invention refers to an electronic article (1), comprising a nickel layer or a cobalt layer (4), wherein the nickel layer or the cobalt layer (4) is obtained according to the method of the present invention, wherein the nickel layer (4) or the cobalt layer (4) comprises 99 wt% or more nickel or cobalt, based on the total weight of the nickel layer (4) or the cobalt layer (4), wherein the article comprises a copper layer (3), and wherein the nickel layer (4) or the cobalt layer (4) is disposed on the copper layer, and further comprising a gold layer (5) or tin layer (5) on the nickel layer (4) or on the cobalt layer (4), respectively.
  • the electronic article of the present invention is also called an electronic device or electronic component or electronic part.
  • the article of the present invention is preferably a product of the method of the present invention, for example the plated substrate. In this connection, it is referred to the whole disclosure above.
  • the copper layer (4) is structured, more preferably forms a circuitry.
  • the electronic article is preferably selected from wafers, diced and/or further processed wafers, micro electro mechanical systems, integrated circuit packages, and printed circuit boards.
  • a preferred electronic article is a sensor, e.g. comprised in a micro electro mechanical systems.
  • an electronic article further comprising a gold layer or a tin layer, wherein the gold layer or the tin layer is disposed on the nickel layer or on the cobalt layer.
  • the nickel or cobalt layer does not comprise phosphor (also called in this description "phosphorus").
  • Fig. 1 shows an electronic article of the invention.
  • Nickel sulfate hexahydrate
  • the reducing agent is synthesized in a regeneration cell as described in WO 2013/182478 A2 .
  • the finally obtained reducing agent solution comprises 0.8 M Ti 3+ and 0.2 M Ti 4+ .
  • printed circuit boards comprising a non-conductive base material (FR4, a resin) and patterned copper are used. Plating was carried out for 60 minutes. Thereafter a nickel layer with a thickness of approximately 300 nm selectively on copper was obtained (FR4 was not affected).
  • FR4 non-conductive base material
  • the thickness of the nickel layer was measured with XRF throughout all examples.
  • Example 2 Substrates as used in Example 1 are also utilized in Example 2. Plating is carried out for 30 minutes, wherein after 30 minutes a selectively plated cobalt layer with a thickness of approximately 160 nm to 180 nm is obtained, corresponding to a plating rate of approximately 320 nm/h.
  • Example 3 Electronic article:
  • Fig. 1 shows (not true to scale) an electronic article 1, for example a printed circuit board or a wafer, comprising a nickel layer 4 or a cobalt layer 4.
  • the nickel layer 4 or the cobalt layer 4 was produced by contacting a substrate 2, 3 with a plating solution of the invention.
  • the substrate 2, 3 comprises a carrier body 2, for example a wafer, and a copper layer 3 which is arranged on a surface of the carrier body 2.
  • a cobalt layer 4 or a nickel layer 4 is plated on the copper layer 3 without further activation of the copper layer 3.
  • a gold layer 5 or a tin layer 5 is plated on the nickel layer 4 or the cobalt layer 4.
  • the cobalt layer 4 or nickel layer 4 serves as a barrier layer between the copper layer 3 and the gold layer 5 or tin layer 5.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemically Coating (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
EP20179312.2A 2020-06-10 2020-06-10 Stromlose nickel- oder kobaltplattierungslösung Pending EP3922753A1 (de)

Priority Applications (7)

Application Number Priority Date Filing Date Title
EP20179312.2A EP3922753A1 (de) 2020-06-10 2020-06-10 Stromlose nickel- oder kobaltplattierungslösung
TW110121157A TW202204690A (zh) 2020-06-10 2021-06-10 無電鎳或鈷電鍍溶液
JP2022576217A JP2023529933A (ja) 2020-06-10 2021-06-10 無電解ニッケルまたはコバルトめっき溶液
CN202180047811.5A CN115836142A (zh) 2020-06-10 2021-06-10 无电镍或钴电镀溶液
PCT/EP2021/065564 WO2021250146A1 (en) 2020-06-10 2021-06-10 Electroless nickel or cobalt plating solution
KR1020237000473A KR20230022959A (ko) 2020-06-10 2021-06-10 무전해 니켈 또는 코발트 도금 용액
US18/001,346 US20230235462A1 (en) 2020-06-10 2021-06-10 Electroless nickel or cobalt plating solution

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EP20179312.2A EP3922753A1 (de) 2020-06-10 2020-06-10 Stromlose nickel- oder kobaltplattierungslösung

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EP (1) EP3922753A1 (de)
JP (1) JP2023529933A (de)
KR (1) KR20230022959A (de)
CN (1) CN115836142A (de)
TW (1) TW202204690A (de)
WO (1) WO2021250146A1 (de)

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WO2021250146A1 (en) 2021-12-16
KR20230022959A (ko) 2023-02-16
US20230235462A1 (en) 2023-07-27
TW202204690A (zh) 2022-02-01
CN115836142A (zh) 2023-03-21

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