WO2024157150A1 - Phosphorus-containing chemical solution suitable for polishing copper and alloys thereof by plasma electropolishing - Google Patents
Phosphorus-containing chemical solution suitable for polishing copper and alloys thereof by plasma electropolishing Download PDFInfo
- Publication number
- WO2024157150A1 WO2024157150A1 PCT/IB2024/050590 IB2024050590W WO2024157150A1 WO 2024157150 A1 WO2024157150 A1 WO 2024157150A1 IB 2024050590 W IB2024050590 W IB 2024050590W WO 2024157150 A1 WO2024157150 A1 WO 2024157150A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- phosphate
- electropolishing
- group
- salt selected
- plasma
- Prior art date
Links
- 239000010949 copper Substances 0.000 title claims description 16
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims description 11
- 229910052802 copper Inorganic materials 0.000 title claims description 11
- 229910045601 alloy Inorganic materials 0.000 title claims description 9
- 239000000956 alloy Substances 0.000 title claims description 9
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 title claims description 7
- 239000011574 phosphorus Substances 0.000 title claims description 7
- 229910052698 phosphorus Inorganic materials 0.000 title claims description 7
- 238000005498 polishing Methods 0.000 title abstract description 18
- 239000000126 substance Substances 0.000 title description 7
- 229910052751 metal Inorganic materials 0.000 claims abstract description 41
- 239000002184 metal Substances 0.000 claims abstract description 41
- 238000000034 method Methods 0.000 claims abstract description 38
- 230000008569 process Effects 0.000 claims abstract description 34
- 239000000203 mixture Substances 0.000 claims abstract description 31
- 150000003839 salts Chemical class 0.000 claims abstract description 28
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 43
- 239000000243 solution Substances 0.000 claims description 25
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 21
- MNNHAPBLZZVQHP-UHFFFAOYSA-N diammonium hydrogen phosphate Chemical compound [NH4+].[NH4+].OP([O-])([O-])=O MNNHAPBLZZVQHP-UHFFFAOYSA-N 0.000 claims description 15
- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 claims description 15
- -1 K4P2O7 Chemical compound 0.000 claims description 12
- 229910000388 diammonium phosphate Inorganic materials 0.000 claims description 12
- 239000007864 aqueous solution Substances 0.000 claims description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 9
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 9
- 239000001488 sodium phosphate Substances 0.000 claims description 9
- 235000019838 diammonium phosphate Nutrition 0.000 claims description 8
- 238000007254 oxidation reaction Methods 0.000 claims description 8
- 150000002739 metals Chemical class 0.000 claims description 7
- IIACRCGMVDHOTQ-UHFFFAOYSA-N sulfamic acid Chemical compound NS(O)(=O)=O IIACRCGMVDHOTQ-UHFFFAOYSA-N 0.000 claims description 7
- YWYZEGXAUVWDED-UHFFFAOYSA-N triammonium citrate Chemical compound [NH4+].[NH4+].[NH4+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O YWYZEGXAUVWDED-UHFFFAOYSA-N 0.000 claims description 7
- 239000005696 Diammonium phosphate Substances 0.000 claims description 6
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 6
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 6
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 claims description 6
- 229910000148 ammonium phosphate Inorganic materials 0.000 claims description 6
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 claims description 6
- 229910000396 dipotassium phosphate Inorganic materials 0.000 claims description 6
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 claims description 6
- 229910000397 disodium phosphate Inorganic materials 0.000 claims description 6
- 229910000402 monopotassium phosphate Inorganic materials 0.000 claims description 6
- 235000019799 monosodium phosphate Nutrition 0.000 claims description 6
- AVTYONGGKAJVTE-OLXYHTOASA-L potassium L-tartrate Chemical compound [K+].[K+].[O-]C(=O)[C@H](O)[C@@H](O)C([O-])=O AVTYONGGKAJVTE-OLXYHTOASA-L 0.000 claims description 6
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 claims description 6
- 239000001472 potassium tartrate Substances 0.000 claims description 6
- 229940111695 potassium tartrate Drugs 0.000 claims description 6
- 235000011005 potassium tartrates Nutrition 0.000 claims description 6
- 229910052708 sodium Inorganic materials 0.000 claims description 6
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 6
- 229910000162 sodium phosphate Inorganic materials 0.000 claims description 6
- 239000001433 sodium tartrate Substances 0.000 claims description 6
- 229960002167 sodium tartrate Drugs 0.000 claims description 6
- 235000011004 sodium tartrates Nutrition 0.000 claims description 6
- RYCLIXPGLDDLTM-UHFFFAOYSA-J tetrapotassium;phosphonato phosphate Chemical compound [K+].[K+].[K+].[K+].[O-]P([O-])(=O)OP([O-])([O-])=O RYCLIXPGLDDLTM-UHFFFAOYSA-J 0.000 claims description 6
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 claims description 6
- 235000019820 disodium diphosphate Nutrition 0.000 claims description 5
- 230000003647 oxidation Effects 0.000 claims description 5
- 235000019797 dipotassium phosphate Nutrition 0.000 claims description 4
- 235000019800 disodium phosphate Nutrition 0.000 claims description 4
- 235000019796 monopotassium phosphate Nutrition 0.000 claims description 4
- LXAHHHIGZXPRKQ-UHFFFAOYSA-N 5-fluoro-2-methylpyridine Chemical compound CC1=CC=C(F)C=N1 LXAHHHIGZXPRKQ-UHFFFAOYSA-N 0.000 claims description 3
- 239000004254 Ammonium phosphate Substances 0.000 claims description 3
- GEHMBYLTCISYNY-UHFFFAOYSA-N Ammonium sulfamate Chemical compound [NH4+].NS([O-])(=O)=O GEHMBYLTCISYNY-UHFFFAOYSA-N 0.000 claims description 3
- ZGTMUACCHSMWAC-UHFFFAOYSA-L EDTA disodium salt (anhydrous) Chemical compound [Na+].[Na+].OC(=O)CN(CC([O-])=O)CCN(CC(O)=O)CC([O-])=O ZGTMUACCHSMWAC-UHFFFAOYSA-L 0.000 claims description 3
- 239000007836 KH2PO4 Substances 0.000 claims description 3
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 claims description 3
- 235000019289 ammonium phosphates Nutrition 0.000 claims description 3
- BWKOZPVPARTQIV-UHFFFAOYSA-N azanium;hydron;2-hydroxypropane-1,2,3-tricarboxylate Chemical compound [NH4+].OC(=O)CC(O)(C(O)=O)CC([O-])=O BWKOZPVPARTQIV-UHFFFAOYSA-N 0.000 claims description 3
- YXVFQADLFFNVDS-UHFFFAOYSA-N diammonium citrate Chemical compound [NH4+].[NH4+].[O-]C(=O)CC(O)(C(=O)O)CC([O-])=O YXVFQADLFFNVDS-UHFFFAOYSA-N 0.000 claims description 3
- GYQBBRRVRKFJRG-UHFFFAOYSA-L disodium pyrophosphate Chemical compound [Na+].[Na+].OP([O-])(=O)OP(O)([O-])=O GYQBBRRVRKFJRG-UHFFFAOYSA-L 0.000 claims description 3
- 229940038485 disodium pyrophosphate Drugs 0.000 claims description 3
- 235000019837 monoammonium phosphate Nutrition 0.000 claims description 3
- 239000006012 monoammonium phosphate Substances 0.000 claims description 3
- 229910000403 monosodium phosphate Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 229910000160 potassium phosphate Inorganic materials 0.000 claims description 3
- 235000011009 potassium phosphates Nutrition 0.000 claims description 3
- BTAAXEFROUUDIL-UHFFFAOYSA-M potassium;sulfamate Chemical compound [K+].NS([O-])(=O)=O BTAAXEFROUUDIL-UHFFFAOYSA-M 0.000 claims description 3
- 235000011008 sodium phosphates Nutrition 0.000 claims description 3
- YIVJSMIYMAOVSJ-UHFFFAOYSA-N sodium;phosphono dihydrogen phosphate Chemical compound [Na+].OP(O)(=O)OP(O)(O)=O YIVJSMIYMAOVSJ-UHFFFAOYSA-N 0.000 claims description 3
- QDWYPRSFEZRKDK-UHFFFAOYSA-M sodium;sulfamate Chemical compound [Na+].NS([O-])(=O)=O QDWYPRSFEZRKDK-UHFFFAOYSA-M 0.000 claims description 3
- JBQYATWDVHIOAR-UHFFFAOYSA-N tellanylidenegermanium Chemical compound [Te]=[Ge] JBQYATWDVHIOAR-UHFFFAOYSA-N 0.000 claims description 3
- VKFFEYLSKIYTSJ-UHFFFAOYSA-N tetraazanium;phosphonato phosphate Chemical compound [NH4+].[NH4+].[NH4+].[NH4+].[O-]P([O-])(=O)OP([O-])([O-])=O VKFFEYLSKIYTSJ-UHFFFAOYSA-N 0.000 claims description 3
- 229910000404 tripotassium phosphate Inorganic materials 0.000 claims description 3
- 235000019798 tripotassium phosphate Nutrition 0.000 claims description 3
- 229910000406 trisodium phosphate Inorganic materials 0.000 claims description 3
- 235000019801 trisodium phosphate Nutrition 0.000 claims description 3
- 229910006147 SO3NH2 Inorganic materials 0.000 claims description 2
- 230000008901 benefit Effects 0.000 description 5
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 150000007513 acids Chemical class 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- 229910001369 Brass Inorganic materials 0.000 description 2
- 229910001006 Constantan Inorganic materials 0.000 description 2
- 229910000570 Cupronickel Inorganic materials 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 2
- 229910000990 Ni alloy Inorganic materials 0.000 description 2
- 229910004590 P2O7 Inorganic materials 0.000 description 2
- KOMIMHZRQFFCOR-UHFFFAOYSA-N [Ni].[Cu].[Zn] Chemical compound [Ni].[Cu].[Zn] KOMIMHZRQFFCOR-UHFFFAOYSA-N 0.000 description 2
- 239000010951 brass Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000001994 activation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 239000010410 layer Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000004506 ultrasonic cleaning Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
- C25F3/22—Polishing of heavy metals
Definitions
- the invention relates to a composition for plasma electropolishing of metal surfaces and to an electropolishing process using said composition.
- the invention concerns a composition consisting of an aqueous solution of a salt containing phosphorus in +5 oxidation state, a second salt and phosphoric acid, and an associated plasma electropolishing electropolishing process.
- the present invention relates to a process for plasma electropolishing of metal surfaces. More specifically, the present invention relates to the composition of the polishing solution and the optimal process parameters to be applied to the plasma electropolishing electropolishing process for metal surfaces such as copper (Cu), cupronickel, constantan, brass, copper-zinc-nickel alloys, and copper-based alloys.
- metal surfaces such as copper (Cu), cupronickel, constantan, brass, copper-zinc-nickel alloys, and copper-based alloys.
- polishing of metal surfaces is carried out through chemical or electrochemical processes.
- the workpiece to be treated is immersed in a concentrated aqueous solution of several acids, the action of which removes a surface layer of metal, acting preferentially upon the irregularities of the surface and reducing the roughness thereof.
- the workpiece to be treated is immersed in a concentrated aqueous solution of several acids and connected to the positive pole of an electric circuit, thus acting as the anode of an electrolytic cell.
- a second metal electrode immersed in the same solution and facing the workpiece from a suitable distance (usually about ten centimeters), acts as the cathode.
- the application of a potential difference across the anode and the cathode triggers an oxidation reaction on the metal of the workpiece, thereby partially dissolving it into the solution.
- Such oxidation reaction occurs preferentially on the irregularities of the metal surface, which are thus dissolved to a greater extent and smoothed out.
- the overall effect is a reduction in the workpiece's roughness.
- the solutions used for chemical polishing consist of concentrated solutions of acids (e.g., acetic acid, phosphoric acid, nitric acid, hydrochloric acid) or mixtures of sulphamic acid, ammonium citrate, n-butanol and hydrogen peroxide.
- the solutions most commonly used for electropolishing consist of phosphoric acid (H3PO4) in aqueous solution with the addition of moderators such as butanol, ethylene glycol and glycerol; the operating voltage varies between 0.2V and 2.2V.
- PEP plasma electropolishing
- plasma electrolytic polishing PEP
- PEP plasma electrolytic polishing
- This process is well known in the industry, and is applied to various metals and alloys, such as chrome-cobalt-molybdenum and stainless steel, for which polishing recipes are available.
- metals and alloys such as chrome-cobalt-molybdenum and stainless steel, for which polishing recipes are available.
- some compositions are known in the literature for plasma electropolishing [I. A. Kostogrud, E. V. Boyko, P. E.
- Patent RU 2127334 describes a process consisting of two distinct steps requiring different compositions and process conditions, thus being more complex and time-consuming than the one disclosed in the present invention, which only requires one step.
- the present invention relates, in general, to a composition of a solution to be used in a plasma electropolishing process for metal surfaces. More specifically, the invention relates to an aqueous solution containing: A) a salt containing phosphorus, wherein phosphorus exhibits the +5 oxidation state; B) a second salt; C) phosphoric acid. Furthermore, the present invention defines a plasma electropolishing process for metal surfaces that uses said solution.
- the object of the invention is the composition of an aqueous solution of phosphoric acid for use in a plasma electropolishing process for metal surfaces; said solution comprises at least one compound selected, respectively, from the following groups:
- a salt containing phosphorus in +5 oxidation state selected from: potassium pyrophosphate, K4P2O7, sodium pyrophosphate, Na4P2O7, ammonium pyrophosphate, (NH4)4P207, disodium pyrophosphate, Na2H2P2O7, diammonium phosphate, (NH 4 ) 2 HPO4, monoammonium phosphate, NH4H2PO4, ammonium phosphate, (NH 4 )3PO 4 , disodium phosphate, Na 2 HPO 4 , dipotassium phosphate, K 2 HPO 4 , sodium phosphate, Na3PO4, potassium phosphate, K3PO4, monosodium phosphate, NaH2PO4, monopotassium phosphate, KH 2 PO 4 ;
- B sodium and potassium tartrate, C4H4KNaO6, tribasic ammonium citrate, (NH4)3-Cit, dibasic ammonium citrate, (NH4)2H-Cit, monobasic ammonium citrate, (NH4)H2-Cit, citric acid, ammonium sulfamate, ([NH4]SO3NH2), sodium sulfamate, NaSO3NH2, potassium sulfamate, KSO3NH2, sulphamic acid, H2NSO3H, EDTA disodium, EDTA-Na2, ethylenediaminetetraacetic acid, EDTA;
- said plasma electropolishing process relates tometai surfaces made of any of the following metals: copper (Cu), zinc (Zn), nickel (Ni), or alloys containing such metals.
- FIG. 1 Schematic description of the plasma electropolishing process.
- 1 - surface to be treated 1 - composition for plasma electropolishing, 3 - second metal element, 4 - positive pole, 5 - negative pole, 6 - voltage generator.
- surface to be polished means any object having an exposed metal surface whose roughness has to be reduced;
- anode means the electrode of an electrochemical cell undergoing an oxidation reaction, and
- cathode means the electrode where a reduction reaction occurs.
- a composition of soluble salts in aqueous solution is provided for use in a plasma electropolishing process for metal surfaces as set out in claim 1.
- the present invention concerns an aqueous solution of phosphoric acid for use in a plasma electropolishing process for metal surfaces; said solution comprises at least one compound selected, respectively, from the following groups:
- a salt containing phosphorus in +5 oxidation state selected from: potassium pyrophosphate, K4P2O7, sodium pyrophosphate, Na4P2O7, ammonium pyrophosphate, (NH 4 ) 4 P2O7, disodium pyrophosphate, Na 2 H 2 P2O7, diammonium phosphate, (NH 4 ) 2 HPO4, monoammonium phosphate, NH4H2PO4, ammonium phosphate, (NH 4 )3PO 4 , disodium phosphate, Na 2 HPO 4 , dipotassium phosphate, K 2 HPO 4 , sodium phosphate, Na3PO4, potassium phosphate, K3PO4, monosodium phosphate, NaH2PO4, monopotassium phosphate, KH2PO4;
- B sodium and potassium tartrate, C4H4KNaO6, tribasic ammonium citrate, (NH4)3-Cit, dibasic ammonium citrate, (NH4)H-Cit, monobasic ammonium citrate, (NH4)H2-Cit, citric acid, ammonium sulfamate, ([NH4]SO3NF2), sodium sulfamate, NaSO3NH2, potassium sulfamate, KSO3NH2, sulphamic acid, H2NSO3H, EDTA disodium, EDTA-Na2., ethylenediaminetetraacetic acid, EDTA;
- the mass concentration of the salt selected from group A is comprised between 2.0% and 6.0%
- the mass concentration of the salt selected from group B is comprised between 0.1% and 2.0%
- the concentration of phosphoric acid is such as to reach a pH value of the solution comprised between 2 and 5.
- the salt selected from group A is potassium pyrophosphate (K4P2O7) with a mass concentration of 3.0% to 5.0%
- the salt selected from group B is sodium and potassium tartrate (C4H4KNaOe) with a mass concentration between 0.5% to 1.0%
- the concentration of phosphoric acid is such as to give a pH value of the solution comprised between 2 and 5.
- Phosphoric acid concentration should thus be comprised between 12 ml/l and 30 ml/l.
- the salt selected from group A is diammonium phosphate ((NH 4 )2HPO 4 ) with a mass concentration of between 2.0% to 6.0%
- the salt selected from group B is tribasic ammonium citrate ((NH 4 )3-Cit) with a mass concentration of between 0.3% to 1.5%
- the concentration of phosphoric acid is such as to give a pH value of the solution comprised between 3 and 4.
- Phosphoric acid concentration should thus be comprised between 17 ml/l and 50 ml/l.
- the salt selected from group A is potassium pyrophosphate (K4P2O7) with a mass concentration of 4.0%
- the salt selected from group B is sodium and potassium tartrate (C4H4KNaO6) with a mass concentration of 1.0%
- the concentration of phosphoric acid is such as to give a pH value of the solution of 4.
- Phosphoric acid concentration should thus be comprised between 17 ml/l and 24 ml/l.
- the salt selected from group A is diammonium phosphate ((NH4)2HPO4) with a mass concentration of 3.0%
- the salt selected from group B is tribasic ammonium citrate ((NH 4 )3-Cit) with a mass concentration of 0.5%
- the concentration of phosphoric acid is such as to give a pH value of the solution of 4.
- Phosphoric acid concentration should thus be comprised between 22 ml/l and 30 ml/l.
- the solution composition described herein is used in a plasma electropolishing process for metal surfaces comprising one of the following metals: copper (Cu), zinc (Zn), nickel (Ni), or alloys containing such metals.
- the plasma electropolishing process defined by the present invention comprises the following steps: a) Placing the metal surface to be polished 1 in contact with the composition 2; b) Placing at least one further metal element 3 in contact with said composition 2, so that electrical contact between the metal surfaces 1 and 3 is ensured through said composition 2; c) Connecting the metal surface to be polished 1 to the positive pole 4 of a voltage generator 6 and the further metal element 3 to the negative pole 5 of said voltage generator 6, so that the metal surface to be polished 1 acts as an anode of an electrochemical cell; d) Increasing the temperature of the composition so that it is comprised between 40°C and 95°C; e) Applying a continuous potential difference comprised between 200 V and 400 V across the two electrodes.
- the potential difference applied across the two electrodes is 300 V, while the temperature of the solution is maintained at 75°C.
- One advantage of the present invention over the prior art is the speed at which the desired treatment is accomplished; as a matter of fact, the process according to the invention has proven to be 10 times faster than conventional electropolishing, and approximately 3.5 times faster than chemical polishing.
- a further advantage of the present invention over the prior art is its higher efficiency; in fact, the polishing effect is achieved on the treated surface by removing less material than required by the processes currently known in the art.
- compositions of the present invention which, being made up of solutions with lower concentrations, are less harmful for the environment and the health of operators than those used in the prior art.
- a further advantage of the invention relates to the capability of removing contaminants from the processed surface due to the higher power used per area unit, thus avoiding the need for pretreatments as commonly required by conventional electropolishing and chemical polishing processes: (degreasing, ultrasonic cleaning, activation, polishing).
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
Abstract
The invention relates to a process for electrochemical polishing of metal surfaces known as plasma electropolishing electropolishing (PEP), which uses a salt-based solution. The present invention provides ideal compositions of the polishing solution and optimal process parameters to attain better results over traditional electropolishing techniques.
Description
PHOSPHORUS-CONTAINING CHEMICAL SOLUTION SUITABLE FOR POLISHING COPPER AND ALLOYS
THEREOF BY PLASMA ELECTROPOLISHING
Technical field of the invention
The invention relates to a composition for plasma electropolishing of metal surfaces and to an electropolishing process using said composition. In particular, the invention concerns a composition consisting of an aqueous solution of a salt containing phosphorus in +5 oxidation state, a second salt and phosphoric acid, and an associated plasma electropolishing electropolishing process.
Prior art
The present invention relates to a process for plasma electropolishing of metal surfaces. More specifically, the present invention relates to the composition of the polishing solution and the optimal process parameters to be applied to the plasma electropolishing electropolishing process for metal surfaces such as copper (Cu), cupronickel, constantan, brass, copper-zinc-nickel alloys, and copper-based alloys.
Typically, the polishing of metal surfaces is carried out through chemical or electrochemical processes.
In chemical polishing, the workpiece to be treated is immersed in a concentrated aqueous solution of several acids, the action of which removes a surface layer of metal, acting preferentially upon the irregularities of the surface and reducing the roughness thereof.
In the electrochemical process, also referred to as electropolishing or electrolytic polishing, the workpiece to be treated is immersed in a concentrated aqueous solution of several acids and connected to the positive pole of an electric circuit, thus acting as the anode of an electrolytic cell. A second metal electrode, immersed in the same solution and facing the workpiece from a suitable distance (usually about ten centimeters), acts as the cathode. The application of a potential difference across the anode and the cathode triggers an oxidation reaction on the metal of the workpiece, thereby partially dissolving it into the solution. Such oxidation reaction occurs preferentially on the irregularities of the metal surface, which are thus dissolved to a greater extent and smoothed out. The overall effect is a reduction in the workpiece's roughness.
With reference to copper or copper alloy surfaces, the solutions used for chemical polishing consist of concentrated solutions of acids (e.g., acetic acid, phosphoric acid, nitric acid, hydrochloric acid) or mixtures of sulphamic acid, ammonium citrate, n-butanol and hydrogen peroxide. On the other hand, the solutions most commonly used for electropolishing consist of phosphoric acid (H3PO4) in
aqueous solution with the addition of moderators such as butanol, ethylene glycol and glycerol; the operating voltage varies between 0.2V and 2.2V.
An alternative approach is the so-called plasma electropolishing, or plasma electrolytic polishing (PEP), which differs from traditional electropolishing for the higher voltages employed, between 200 V and 400 V, which ensure faster processing times and permit the use of diluted solutions. In fact, PEP uses diluted aqueous solutions of salts, which permit the creation of a uniform layer of vapor and gas, in which the surface smoothing process can take place. This process is well known in the industry, and is applied to various metals and alloys, such as chrome-cobalt-molybdenum and stainless steel, for which polishing recipes are available. As concerns copper and its alloys, some compositions are known in the literature for plasma electropolishing [I. A. Kostogrud, E. V. Boyko, P. E. Matochkin, and D. V. Sorokin, 'Comparing the methods of copper substrate polishing for CVD graphene synthesis', J. Phys.: Conf. Ser., vol. 2057, no. 1, p. 012121, Oct. 2021, doi: 10.1088/1742- 6596/2057/1/012121; United States patent US20100200424A1; Belarussian patent BY 11410; Russian patent RU 2127334; Belarussian patent BY 8424; Russian patent RU2013129493A], which, however, do not guarantee a sufficient roughness reduction to obtain a mirror finish of the surface. In particular, the above-mentioned patent US20100200424A1 claims a process that requires a significantly lower voltage than described herein, thus not ensuring good polishing results. Patent RU 2127334 describes a process consisting of two distinct steps requiring different compositions and process conditions, thus being more complex and time-consuming than the one disclosed in the present invention, which only requires one step.
Notwithstanding the advantages offered by plasma electropolishing over the other polishing methods described above, it is still remains challengingto identify optimal electrolyte composition parameters and ideal time and current conditions for processing other metals.
It is the object of the present invention to provide a polishing solution composition and optimal process parameters to be applied to a plasma electropolishing process for processing metal surfaces of copper (Cu), cupronickel, constantan, brass, copper-zinc-nickel alloys, and copper-based alloys, such as to give better results than traditional electropolishing techniques.
Summary of the invention
The present invention relates, in general, to a composition of a solution to be used in a plasma electropolishing process for metal surfaces. More specifically, the invention relates to an aqueous solution containing: A) a salt containing phosphorus, wherein phosphorus exhibits the +5 oxidation state; B) a second salt; C) phosphoric acid.
Furthermore, the present invention defines a plasma electropolishing process for metal surfaces that uses said solution.
The object of the invention is the composition of an aqueous solution of phosphoric acid for use in a plasma electropolishing process for metal surfaces; said solution comprises at least one compound selected, respectively, from the following groups:
A. a salt containing phosphorus in +5 oxidation state, selected from: potassium pyrophosphate, K4P2O7, sodium pyrophosphate, Na4P2O7, ammonium pyrophosphate, (NH4)4P207, disodium pyrophosphate, Na2H2P2O7, diammonium phosphate, (NH4)2HPO4, monoammonium phosphate, NH4H2PO4, ammonium phosphate, (NH4)3PO4, disodium phosphate, Na2HPO4, dipotassium phosphate, K2HPO4, sodium phosphate, Na3PO4, potassium phosphate, K3PO4, monosodium phosphate, NaH2PO4, monopotassium phosphate, KH2PO4;
B. sodium and potassium tartrate, C4H4KNaO6, tribasic ammonium citrate, (NH4)3-Cit, dibasic ammonium citrate, (NH4)2H-Cit, monobasic ammonium citrate, (NH4)H2-Cit, citric acid, ammonium sulfamate, ([NH4]SO3NH2), sodium sulfamate, NaSO3NH2, potassium sulfamate, KSO3NH2, sulphamic acid, H2NSO3H, EDTA disodium, EDTA-Na2, ethylenediaminetetraacetic acid, EDTA;
C. Phosphoric acid in a concentration to achieve a pH between 2 and 5.
It is a further object of the present invention to provide a plasma electropolishing process that uses said composition. In particular, said plasma electropolishing process relates tometai surfaces made of any of the following metals: copper (Cu), zinc (Zn), nickel (Ni), or alloys containing such metals.
Brief description of the drawings
Figure 1: Schematic description of the plasma electropolishing process.
Key:
1 - surface to be treated, 2 - composition for plasma electropolishing, 3 - second metal element, 4 - positive pole, 5 - negative pole, 6 - voltage generator.
Detailed description of the invention
In the description of the present invention, "surface to be polished" means any object having an exposed metal surface whose roughness has to be reduced; "anode" means the electrode of an electrochemical cell undergoing an oxidation reaction, and "cathode" means the electrode where a reduction reaction occurs.
According to the present invention, a composition of soluble salts in aqueous solution is provided for use in a plasma electropolishing process for metal surfaces as set out in claim 1.
For a better understanding of the present invention, a preferred embodiment thereof will be described below merely by way of non-limiting example.
The present invention concerns an aqueous solution of phosphoric acid for use in a plasma electropolishing process for metal surfaces; said solution comprises at least one compound selected, respectively, from the following groups:
A. a salt containing phosphorus in +5 oxidation state, selected from: potassium pyrophosphate, K4P2O7, sodium pyrophosphate, Na4P2O7, ammonium pyrophosphate, (NH4)4P2O7, disodium pyrophosphate, Na2H2P2O7, diammonium phosphate, (NH4)2HPO4, monoammonium phosphate, NH4H2PO4, ammonium phosphate, (NH4)3PO4, disodium phosphate, Na2HPO4, dipotassium phosphate, K2HPO4, sodium phosphate, Na3PO4, potassium phosphate, K3PO4, monosodium phosphate, NaH2PO4, monopotassium phosphate, KH2PO4;
B. sodium and potassium tartrate, C4H4KNaO6, tribasic ammonium citrate, (NH4)3-Cit, dibasic ammonium citrate, (NH4)H-Cit, monobasic ammonium citrate, (NH4)H2-Cit, citric acid, ammonium sulfamate, ([NH4]SO3NF2), sodium sulfamate, NaSO3NH2, potassium sulfamate, KSO3NH2, sulphamic acid, H2NSO3H, EDTA disodium, EDTA-Na2., ethylenediaminetetraacetic acid, EDTA;
C. Phosphoric acid in a concentration to achievea pH between 2 and 5.
According to one aspect of the invention, the mass concentration of the salt selected from group A is comprised between 2.0% and 6.0%, the mass concentration of the salt selected from group B is comprised between 0.1% and 2.0%, and the concentration of phosphoric acid is such as to reach a pH value of the solution comprised between 2 and 5.
In a preferred embodiment of the invention, the salt selected from group A is potassium pyrophosphate (K4P2O7) with a mass concentration of 3.0% to 5.0%, the salt selected from group B is sodium and potassium tartrate (C4H4KNaOe) with a mass concentration between 0.5% to 1.0%, and the concentration of phosphoric acid is such as to give a pH value of the solution comprised between 2 and 5. Phosphoric acid concentration should thus be comprised between 12 ml/l and 30 ml/l.
In a second preferred embodiment of the invention, the salt selected from group A is diammonium phosphate ((NH4)2HPO4) with a mass concentration of between 2.0% to 6.0%, the salt selected from
group B is tribasic ammonium citrate ((NH4)3-Cit) with a mass concentration of between 0.3% to 1.5%, and the concentration of phosphoric acid is such as to give a pH value of the solution comprised between 3 and 4. Phosphoric acid concentration should thus be comprised between 17 ml/l and 50 ml/l.
In a third preferred embodiment of the invention, the salt selected from group A is potassium pyrophosphate (K4P2O7) with a mass concentration of 4.0%, the salt selected from group B is sodium and potassium tartrate (C4H4KNaO6) with a mass concentration of 1.0%, and the concentration of phosphoric acid is such as to give a pH value of the solution of 4. Phosphoric acid concentration should thus be comprised between 17 ml/l and 24 ml/l.
In a fourth preferred embodiment of the invention, the salt selected from group A is diammonium phosphate ((NH4)2HPO4) with a mass concentration of 3.0%, the salt selected from group B is tribasic ammonium citrate ((NH4)3-Cit) with a mass concentration of 0.5%, and the concentration of phosphoric acid is such as to give a pH value of the solution of 4. Phosphoric acid concentration should thus be comprised between 22 ml/l and 30 ml/l.
Advantageously, according to the invention, the solution composition described herein is used in a plasma electropolishing process for metal surfaces comprising one of the following metals: copper (Cu), zinc (Zn), nickel (Ni), or alloys containing such metals.
With reference to Figure 1, according to another aspect of the invention, the plasma electropolishing process defined by the present invention comprises the following steps: a) Placing the metal surface to be polished 1 in contact with the composition 2; b) Placing at least one further metal element 3 in contact with said composition 2, so that electrical contact between the metal surfaces 1 and 3 is ensured through said composition 2; c) Connecting the metal surface to be polished 1 to the positive pole 4 of a voltage generator 6 and the further metal element 3 to the negative pole 5 of said voltage generator 6, so that the metal surface to be polished 1 acts as an anode of an electrochemical cell; d) Increasing the temperature of the composition so that it is comprised between 40°C and 95°C; e) Applying a continuous potential difference comprised between 200 V and 400 V across the two electrodes.
Advantageously, according to the invention, the potential difference applied across the two electrodes is 300 V, while the temperature of the solution is maintained at 75°C.
It is an objectof the present invention to provide a composition for plasma electropolishing of metal surfaces, as well as an electropolishing process using said composition to overcome the limitations of the prior art.
One advantage of the present invention over the prior art is the speed at which the desired treatment is accomplished; as a matter of fact, the process according to the invention has proven to be 10 times faster than conventional electropolishing, and approximately 3.5 times faster than chemical polishing.
A further advantage of the present invention over the prior art is its higher efficiency; in fact, the polishing effect is achieved on the treated surface by removing less material than required by the processes currently known in the art.
Another advantage relates to the compositions of the present invention which, being made up of solutions with lower concentrations, are less harmful for the environment and the health of operators than those used in the prior art.
A further advantage of the invention relates to the capability of removing contaminants from the processed surface due to the higher power used per area unit, thus avoiding the need for pretreatments as commonly required by conventional electropolishing and chemical polishing processes: (degreasing, ultrasonic cleaning, activation, polishing).
Claims
1. Aqueous solution of phosphoric acid for use in a plasma electropolishing process for metal surfaces, comprising at least one salt selected from the following group A:
A. a salt containing phosphorus in +5 oxidation state, selected from: potassium pyrophosphate, K4P2O7, sodium pyrophosphate, Na4P2O7, ammonium pyrophosphate, (NH4)4P207, disodium pyrophosphate, Na2H2P2O7, diammonium phosphate, (NH4)2HPO4, monoammonium phosphate, NH4H2PO4, ammonium phosphate, (NH4)3PO4, disodium phosphate, Na2HPO4, dipotassium phosphate, K2HPO4, sodium phosphate, Na3PO4, potassium phosphate, K3PO4, monosodium phosphate, NaH2PO4, monopotassium phosphate, KH2PO4; and at least one salt selected from the following group B:
B. sodium and potassium tartrate, C4H4KNaO6, tribasic ammonium citrate, (NH4)3-Cit, dibasic ammonium citrate, (NH4)2H-Cit, monobasic ammonium citrate, (NH4)Hz-Cit, citric acid, ammonium sulfamate, ([NH4]SO3NH2), sodium sulfamate, NaSO3NH2, potassium sulfamate, KSO3NH2, sulphamic acid, H2NSO3H, EDTA disodium, EDTA-Na2, ethylenediaminetetraacetic acid, EDTA.
2. Composition according to the preceding claim, wherein the mass concentration of the salt selected from group A is comprised between 2.0% and 6.0%, the mass concentration of the salt selected from group B is comprised between 0.1% and 2.0%, and the concentration of phosphoric acid is such as to reach a pH value of the solution comprised between 2 and 5.
3. Composition according to the preceding claims, wherein the salt selected from group A is potassium pyrophosphate (K4P2O7) with a mass concentration of 4.0%, the salt selected from group B is sodium and potassium tartrate (C4H4KNaO6) with a mass concentration of 1.0%, and the concentration of phosphoric acid is such as to give a pH value of the solution equal to 4.
4. Composition according to the preceding claims, wherein the salt selected from group A is diammonium phosphate ((NH4)2HPO4) with a mass concentration of 3.0%, the salt selected from group B is tribasic ammonium citrate ((NH4)3-Cit) with a mass concentration of 0.5%, and the concentration of phosphoric acid is such as to give a pH value of the solution of 4.
5. Plasma electropolishing process for metal surfaces using the composition according to one of the preceding claims, comprising the steps of: a) Placing the metal surface to be polished (1) in contact with the composition (2);
b) Placing at least one further metal element (3) in contact with the same composition (2), so that electrical contact between the metal surfaces (1) and (3) is ensured through said composition (2); c) Connecting the metal surface to be polished (1) to the positive pole (4) and the further metal element (3) to the negative pole (5) of a voltage generator (6), so that the metal surface to be polished (1) acts as an anode of an electrochemical cell; d) Increasing the temperature of the composition so that it is comprised between 40°C and 95°C; e) Applying a continuous potential difference comprised between 200 V and 400 V across the two electrodes.
6. Process according to the preceding claim, wherein the metal surface to be polished (1) comprises at least one of: copper (Cu), zinc (Zn), nickel (Ni), or an alloy of said metals.
7. Process according to the preceding claim, wherein the potential difference applied across the two electrodes is 300 V.
8. Process according to the preceding claim, wherein the temperature of the solution is maintained at 75°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT102023000001221 | 2023-01-27 | ||
| IT202300001221 | 2023-01-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2024157150A1 true WO2024157150A1 (en) | 2024-08-02 |
Family
ID=85936953
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IB2024/050590 WO2024157150A1 (en) | 2023-01-27 | 2024-01-22 | Phosphorus-containing chemical solution suitable for polishing copper and alloys thereof by plasma electropolishing |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2024157150A1 (en) |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2582020A (en) * | 1947-07-15 | 1952-01-08 | Gen Motors Corp | Electrolytic polishing |
| RU2127334C1 (en) * | 1996-12-03 | 1999-03-10 | Уфимский государственный авиационный технический университет | Method of polishing copper and copper-base alloys |
| US20060169597A1 (en) * | 2001-03-14 | 2006-08-03 | Applied Materials, Inc. | Method and composition for polishing a substrate |
| US20100161053A1 (en) * | 2008-12-18 | 2010-06-24 | Biotronik Vi Patent Ag | Implant and Method for Manufacturing |
| CN101845662A (en) * | 2009-03-27 | 2010-09-29 | 比亚迪股份有限公司 | Magnesium alloy surface treating method and magnesium alloy polished by same |
| US20110294293A1 (en) * | 2010-06-01 | 2011-12-01 | Applied Materials, Inc. | Chemical planarization of copper wafer polishing |
| CN110629227A (en) * | 2019-08-14 | 2019-12-31 | 沈阳造币有限公司 | Electrolyte plasma polishing solution and polishing process for coinage copper alloy blank cake |
-
2024
- 2024-01-22 WO PCT/IB2024/050590 patent/WO2024157150A1/en unknown
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2582020A (en) * | 1947-07-15 | 1952-01-08 | Gen Motors Corp | Electrolytic polishing |
| RU2127334C1 (en) * | 1996-12-03 | 1999-03-10 | Уфимский государственный авиационный технический университет | Method of polishing copper and copper-base alloys |
| US20060169597A1 (en) * | 2001-03-14 | 2006-08-03 | Applied Materials, Inc. | Method and composition for polishing a substrate |
| US20100161053A1 (en) * | 2008-12-18 | 2010-06-24 | Biotronik Vi Patent Ag | Implant and Method for Manufacturing |
| CN101845662A (en) * | 2009-03-27 | 2010-09-29 | 比亚迪股份有限公司 | Magnesium alloy surface treating method and magnesium alloy polished by same |
| US20110294293A1 (en) * | 2010-06-01 | 2011-12-01 | Applied Materials, Inc. | Chemical planarization of copper wafer polishing |
| CN110629227A (en) * | 2019-08-14 | 2019-12-31 | 沈阳造币有限公司 | Electrolyte plasma polishing solution and polishing process for coinage copper alloy blank cake |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11136689B2 (en) | Method for the surface finishing of metals and alloys | |
| JPH03501753A (en) | Electrochemical processing method for articles made of conductive materials | |
| JP5690727B2 (en) | Cyanide-free electrolyte composition for galvanic deposition of copper layers | |
| KR101809565B1 (en) | Gold plating solution | |
| CN1242439A (en) | Method and apparatus for quick forming phosphate covering film on steel wire | |
| CN108221041B (en) | Method for electropolishing metal substrates | |
| US4105511A (en) | Process for treating the surface of aluminum or aluminum alloy | |
| US20160376724A1 (en) | Electrolyte and process for the electrolytic polishing of a metallic substrate | |
| US3627654A (en) | Electrolytic process for cleaning high-carbon steels | |
| WO2024157150A1 (en) | Phosphorus-containing chemical solution suitable for polishing copper and alloys thereof by plasma electropolishing | |
| US6332970B1 (en) | Electrolytic method of and compositions for stripping electroless nickel | |
| US2685564A (en) | Electrolytic cleaning process | |
| US2578898A (en) | Electrolytic removal of metallic coatings from various base metals | |
| US20150197870A1 (en) | Method for Plating Fine Grain Copper Deposit on Metal Substrate | |
| US3427232A (en) | Method of electrode plating silver on magnesium | |
| KR100618165B1 (en) | Electrolytic method of and compositions for stripping electroless nickel | |
| US4439282A (en) | Treatment of metals to enhance adhesive bonding | |
| KR100312286B1 (en) | Electrolytic polishing composition for copper or copper alloy substrate and iron-nickel alloy substrate | |
| JP2720116B2 (en) | Electrolytic etchant for copper or copper alloy material | |
| US3630865A (en) | Sequestering agents as additives for alkali chlorates | |
| EP0351771B1 (en) | Non-chrome cleaner/deoxidizer system | |
| JPH0548317B2 (en) | ||
| JPH0699178A (en) | Electrolytical treating method for waste chemical plating liquid | |
| WO2024184764A1 (en) | Chemical solution containing sulphamic acid and hydrogen peroxide, suitable for polishing copper and alloys thereof by plasma electropolishing | |
| CN1041223C (en) | No-etching electroplating iron method for repairing machine parts |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 24705560 Country of ref document: EP Kind code of ref document: A1 |