Electronchemical deposition of tantalum and/or copper in ionic liquids

Abstract

The invention relates to a process for the electrochemical deposition of tantalum and/or copper on a substrate in an ionic liquid comprising at least one tetraalkylammonium, tetraalkylphosphonium, 1,1-dialkylpyrrolidinium, 1-hydroxyalkyl-1-alkylpyrrolidinium, 1-hydroxyalkyl-3-alkylimidazolium or 1,3-bis(hydroxyalkyl)imidazolium cation, where the alkyl groups or the alkylene chain of the hydroxyalkyl group may each, independently of one another, have 1 to 10 C atoms.

1 . Process for the electrochemical deposition of tantalum and/or copper on a substrate in an ionic liquid comprising at least one tetraalkylammonium, tetraalkylphosphonium, 1,1-dialkylpyrrolidinium, 1-hydroxyalkyl-1-alkylpyrrolidinium, 1-hydroxyalkyl-3-alkylimidazolium or 1,3-bis(hydroxyalkyl)imidazolium cation, where the alkyl groups or the alkylene chain of the hydroxyalkyl group may each, independently of one another, have 1 to 10 C atoms. 
   
   
       2 . Process according to  claim 1 , characterised in that the ionic liquid has a broad electrochemical window from −2000 mV to −3500 mV against ferrocene/ferrocinium in the cathodic branch. 
   
   
       3 . Process according to  claim 1 , characterised in that the anion of the ionic liquid is selected from the group of perfluoroalkylsulfonate, perfluoroacetate, bis(fluorosulfonyl)imide, bis(perfluoroalkylsulfonyl)imide, tris(perfluoroalkyl)trifluorophosphate, bis(perfluoroalkyl)tetrafluorophosphate, tris(perfluoroalkylsulfonyl)methide or perfluoroalkylborate. 
   
   
       4 . Process according to  claim 1 , characterised in that the cation is selected from the group of linear or branched tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, tetraheptylammonium, tetraoctylammonium, tetranonylammonium, tetradecylammonium, trimethylalkylammonium, trimethyl(ethyl)ammonium, triethyl(methyl)ammonium, trihexylammonium, methyl(trioctyl)ammonium, tetramethylphosphonium, tetraethylphosphonium, tetrapropylphosphonium, tetrabutylphosphonium, tetrapentylphosphonium, tetrahexylphosphonium, tetraheptylphosphonium, tetraoctylphosphonium, tetranonylphosphonium, tetradecylphosphonium, trihexyltetradecylphosphonium, triisobutyl(methyl)phosphonium, tributyl(ethyl)phosphonium, tributyl(methyl)phosphonium, 1,1-dimethylpyrrolidinium, 1-methyl-1-ethylpyrrolidinium, 1-methyl-1-propylpyrrolidinium, 1-methyl-1-butylpyrrolidinium, 1-methyl-1-pentylpyrrolidinium, 1-methyl-1-hexylpyrrolidinium, 1-methyl-1-heptylpyrrolidinium, 1-methyl-1-octylpyrrolidinium, 1-methyl-1-nonylpyrrolidinium, 1-methyl-1-decylpyrrolidinium, 1,1-diethylpyrrolidinium, 1-ethyl-1-propylpyrrolidinium, 1-ethyl-1-butylpyrrolidinium, 1-ethyl-1-pentylpyrrolidinium, 1-ethyl-1-hexylpyrrolidinium, 1-ethyl-1-heptylpyrrolidinium, 1-ethyl-1-octylpyrrolidinium, 1-ethyl-1-nonylpyrrolidinium, 1-ethyl-1-decylpyrrolidinium, 1,1-dipropylpyrrolidinium, 1-propyl-1-butylpyrrolidinium, 1-propyl-1-pentylpyrrolidinium, 1-propyl-1-hexylpyrrolidinium, 1-propyl-1-heptylpyrrolidinium, 1-propyl-1-octylpyrrolidinium, 1-propyl-1-nonylpyrrolidinium, 1-propyl-1-decylpyrrolidinium, 1,1-dibutylpyrrolidinium, 1-butyl-1-pentylpyrrolidinium, 1-butyl-1-hexylpyrrolidinium, 1-butyl-1-heptylpyrrolidinium, 1-butyl-1-octylpyrrolidinium, 1-butyl-1-nonylpyrrolidinium, 1-butyl-1-decylpyrrolidinium, 1,1-dipentylpyrrolidinium, 1-pentyl-1-hexylpyrrolidinium, 1-pentyl-1-heptylpyrrolidinium, 1-pentyl-1-octylpyrrolidinium, 1-pentyl-1-nonylpyrrolidinium, 1-pentyl-1-decylpyrrolidinium, 1,1-dihexylpyrrolidinium, 1-hexyl-1-heptylpyrrolidinium, 1-hexyl-1-octylpyrrolidinium, 1-hexyl-1-nonylpyrrolidinium, 1-hexyl-1-decylpyrrolidinium, 1,1-dihexylpyrrolidinium, 1-hexyl-1-heptylpyrrolidinium, 1-hexyl-1-octylpyrrolidinium, 1-hexyl-1-nonylpyrrolidinium, 1-hexyl-1-decylpyrrolidinium, 1,1-diheptylpyrrolidinium, 1-heptyl-1-octylpyrrolidinium, 1-heptyl-1-nonylpyrrolidinium, 1-heptyl-1-decylpyrrolidinium, 1,1-dioctylpyrrolidinium, 1-octyl-1-nonylpyrrolidinium, 1-octyl-1-decylpyrrolidinium, 1-1-dinonylpyrrolidinium, 1-nonyl-1-decylpyrrolidinium or 1,1-didecylpyrrolidinium, 1-hydroxymethyl-1-methylpyrrolidinium, 1-hydroxymethyl-1-ethylpyrrolidinium, 1-hydroxymethyl-1-propylpyrrolidinium, 1-hydroxymethyl-1-butylpyrrolidinium, 1-(2-hydroxyethyl)-1-methylpyrrolidinium, 1-(2-hydroxyethyl)-1-ethylpyrrolidinium, 1-(2-hydroxyethyl)-1-propylpyrrolidinium, 1-(2-hydroxyethyl)-1-butylpyrrolidinium, 1-(3-hydroxypropyl)-1-methylpyrrolidinium, 1-(3-hydroxypropyl)-1-ethylpyrrolidinium, 1-(3-hydroxypropyl)-1-propylpyrrolidinium, 1-(3-hydroxypropyl)-1-butylpyrrolidinium, 1-(4-hydroxybutyl)-1-methylpyrrolidinium, 1-(4-hydroxybutyl)-1-ethylpyrrolidinium, 1-(4-hydroxybutyl)-1-propylpyrrolidinium or 1-(4-hydroxybutyl)-1-butylpyrrolidinium, 1-(1-hydroxymethyl)-3-methylimidazolium, 1-(1-hydroxymethyl)-3-ethylimidazolium, 1-(1-hydroxymethyl)-3-propylimidazolium, 1-(1-hydroxymethyl)-3-butylimidazolium, 1-(2-hydroxyethyl)-3-methylimidazolium, 1-(2-hydroxyethyl)-3-ethylimidazolium, 1-(2-hydroxyethyl)-3-propylimidazolium, 1-(2-hydroxyethyl)-3-butylimidazolium, 1-(3-hydroxypropyl)-3-methylimidazolium, 1-(3-hydroxypropyl)-3-ethylimidazolium, 1-(3-hydroxypropyl)-3-propylimidazolium, 1-(3-hydroxypropyl)-3-butylimidazolium, 1-(4-hydroxybutyl)-3-methylimidazolium, 1-(4-hydroxybutyl)-3-ethylimidazolium, 1-(4-hydroxybutyl)-3-propylimidazolium, 1-(4-hydroxybutyl)-3-butylimidazolium, 1,3-bis(1-hydroxymethyl)imidazolium, 1,3-bis(2-hydroxyethyl)imidazolium, 1,3-bis(3-hydroxypropyl)imidazolium, 1,3-bis(4-hydroxybutyl)imidazolium, 1-(2-hydroxyethyl)-3-(1-hydroxymethyl)imidazolium, 1-(2-hydroxyethyl)-3-(3-hydroxypropyl)imidazolium, 1-(2-hydroxyethyl)-3-(4-hydroxybutyl)imidazolium, 1-(3-hydroxypropyl)-3-(1-hydroxymethyl)imidazolium, 1-(3-hydroxypropyl)-3-(2-hydroxyethyl)imidazolium, 1-(3-hydroxypropyl)-3-(4-hydroxybutyl)imidazolium, 1-(4-hydroxybutyl)-3-(1-hydroxymethyl)imidazolium, 1-(4-hydroxybutyl)-3-(2-hydroxyethyl)imidazolium or 1-(4-hydroxybutyl)-3-(3-hydroxypropyl)imidazolium. 
   
   
       5 . Process according to  claim 1 , characterised in that tantalum or copper ions are in dissolved form in the ionic liquid. 
   
   
       6 . Process according to  claim 5 , characterised in that the tantalum or copper ions are produced by anodic oxidation. 
   
   
       7 . Process according to  claim 5 , characterised in that the tantalum or copper ions are produced by dissolution of a tantalum or copper salt. 
   
   
       8 . Process according to  claim 1 , characterised in that an alkali or alkaline earth metal fluoride is present in the ionic liquid for the electrochemical deposition of tantalum. 
   
   
       9 . Process according to  claim 8 , characterised in that the ratio of alkali or alkaline earth metal fluoride to tantalum salt is 2:1 to 1:1. 
   
   
       10 . Process according to  claim 1 , characterised in that the substrate is a non-metal, semi-metal, metal, a metal alloy or conductive and/or metallised ceramics or a conductive and/or metallised plastic. 
   
   
       11 . Process according to  claim 1 , characterised in that, after the deposition of tantalum and/or copper, the ionic liquid is washed out with organic solvents or, in the case of copper, with water. 
   
   
       12 . Electrochemical process for the deposition of tantalum and subsequently copper, in which firstly tantalum in an ionic liquid comprising at least one tetraalkylammonium, tetraalkylphosphonium, 1,1-dialkylpyrrolidinium, 1-hydroxyalkyl-1-alkylpyrrolidinium, 1-hydroxyalkyl-3-alkylimidazolium or 1,3-bis(hydroxyalkyl)imidazolium cation, where the alkyl groups or the alkylene chain of the hydroxyalkyl group may each, independently of one another, have 1 to 10 C atoms, is deposited on a structured silicon chip according to  claim 2 , the tantalum ion-containing ionic liquid is replaced by pure ionic liquid with electrochemical control of the potential, the copper ion-containing ionic liquid is subsequently introduced with control of the potential, and the copper deposition is carried out.