Electrolytic Processing Method and Electrolytic Processing Apparatus

Abstract

An electrolytic processing method makes it possible to preferentially process a diffusion barrier layer while suppressing processing of an interconnect metal, thereby enabling omission of CMP or a lowering of processing pressure in CMP. The electrolytic processing method comprises: bringing a surface of a substrate (W) into contact with an electrolytic solution ( 48 ) comprising an organic solvent, such as propylene carbonate, and an electrolyte, such as lithium hexafluorophosphate, dissolved into the organic solvent, and optionally an inhibitor composed of a heterocyclic compound; and applying an electric potential, for example, a positive electric potential which is controlled at a value less than the decomposition voltage of the organic solvent, to the surface of the substrate (W) to carry out electrolytic processing of the substrate surface.

1 . An electrolytic processing method comprising:
 bringing a surface of a substrate into contact with an electrolytic solution comprising an organic solvent and an electrolyte dissolved into the organic solvent; and   applying an electric potential to the surface of the substrate to carry out electrolytic processing of the substrate surface.   
   
   
       2 . The electrolytic processing method according to  claim 1 , wherein the electrolytic processing is carried out in a constant potential-controlled manner by applying a positive less than the decomposition voltage of the organic solvent, to the surface of the substrate. 
   
   
       3 . The electrolytic processing method according to  claim 1 , wherein the electrolytic solution contains at least one of fluoride ion, chloride ion, bromide ion, iodide ion, hexafluorophosphate ion, tetrafluoroborate ion, and hexafluoroarsenic ion. 
   
   
       4 . The electrolytic processing method according to  claim 1 , wherein the organic solvent is at least one of propylene carbonate, ethylene carbonate, and dimethyl sulfoxide. 
   
   
       5 . The electrolytic processing method according to  claim 1 , wherein the electrolyte is at least one of lithium hexafluorophosphate, tetrabutyl ammonium hexafluorophosphate, tetramethyl ammonium hexafluorophosphate, tetrabutyl ammonium hexafluorophosphate, ammonium tetrafluoroborate, and lithium tetrafluoroborate. 
   
   
       6 . The electrolytic processing method according to  claim 1 , wherein the electrolytic solution further comprises at least one heterocyclic compound having a triazole ring, a pyrrole ring, a pyrazole ring, a thiazole ring, or an imidazole ring. 
   
   
       7 . The electrolytic processing method according to  claim 6 , wherein the heterocyclic compound is a nitrogen-containing heterocyclic compound selected from benzotriazole, pyrrole, 3-(2-thienyl)-1-pyrazole, 2-butyl imidazole, 6-thioguanine, and trithiocyanuric acid. 
   
   
       8 . The electrolytic processing method according to  claim 1 , wherein a barrier layer of tantalum, titanium, tungsten, ruthenium or a compound thereof is formed in the surface of the substrate, and the substrate surface is processed by electrolytic processing. 
   
   
       9 . An electrolytic processing apparatus comprising:
 a substrate holder for holding a substrate;   a processing tool having a processing face for carrying out electrolytic processing of a surface of the substrate;   a power source for applying a voltage between the surface of the substrate and the processing tool; and   an electrolytic cell for holding an electrolytic solution comprising an organic solvent and an electrolyte dissolved into the organic solvent, and bringing the surface of the substrate and the processing face of the processing tool into contact with the electrolytic solution.   
   
   
       10 . The electrolytic processing apparatus according to  claim 9 , wherein the electrolyte is hexafluorophosphate ion. 
   
   
       11 . The electrolytic processing apparatus according to  claim 9  further comprising a controller for adjusting an electric potential applied to the surface of the substrate. 
   
   
       12 . An electrolytic processing method comprising:
 bringing a surface of a substrate having a tantalum film into contact with an electrolytic solution comprising an organic solvent and an electrolyte dissolved into the organic solvent; and   applying an electric potential to the surface of the substrate to carry out electrolytic processing of the substrate surface;   wherein the electrolytic solution contains at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, tetraethyl ammonium tetrafluoroborate, tetra-n-butyl ammonium tetrafluoroborate, tetraethyl ammonium perchlorate, and tetra-n-butyl ammonium bromate.   
   
   
       13 . The electrolytic processing method according to  claim 2 , wherein the electrolytic solution contains at least one of fluoride ion, chloride ion, bromide ion, iodide ion, hexafluorophosphate ion, tetrafluoroborate ion, and hexafluoroarsenic ion. 
   
   
       14 . The electrolytic processing method according to  claim 2 , wherein the organic solvent is at least one of propylene carbonate, ethylene carbonate, and dimethyl sulfoxide. 
   
   
       15 . The electrolytic processing method according to  claim 2 , wherein the electrolyte is at least one of lithium hexafluorophosphate, tetrabutyl ammonium hexafluorophosphate, tetramethyl ammonium hexafluorophosphate, tetrabutyl ammonium hexafluorophosphate, ammonium tetrafluoroborate, and lithium tetrafluoroborate. 
   
   
       16 . The electrolytic processing method according to  claim 2 , wherein the electrolytic solution further comprises at least one heterocyclic compound having a triazole ring, a pyrrole ring, a pyrazole ring, a thiazole ring, or an imidazole ring. 
   
   
       17 . The electrolytic processing method according to  claim 2 , wherein a barrier layer of tantalum, titanium, tungsten, ruthenium or a compound thereof is formed in the surface of the substrate, and the substrate surface is processed by electrolytic processing. 
   
   
       18 . The electrolytic processing apparatus according to  claim 10  further comprising a controller for adjusting an electric potential applied to the surface of the substrate.