Method for Copper Electrodeposition

Abstract

The present invention is related to a method for electroplating a copper deposit onto a substrate, wherein the method comprises the steps of: a) immersing the substrate into an electroplating bath having a copper ion concentration comprised between 0.5 mmol·l −1 and 50 mmol·l −1 , and an acid concentration comprised between 0.05% and 10% per volume of said electroplating bath; and wherein the method further comprises the step of b) electroplating the copper deposit from the electroplating bath onto the substrate. In particular, the present invention is directed to an improved method for the manufacture of semiconductor integrated circuit (IC) devices provided with sub-100 nm features.

1 . A method for electroplating a copper deposit onto a substrate, wherein the method comprises the steps of:
 a. immersing said substrate into an electroplating bath having a copper ion concentration comprised between about 0.5 mmol·l −1  and about 50 mmol·l −1 , and an acid concentration comprised between about 0.05% and about 10% per volume of said electroplating bath; and   b. electroplating the copper deposit from said electroplating bath onto said substrate.   
     
     
         2 . A method according to  claim 1 , wherein the pH of the electroplating bath is acidic, preferably the pH is comprised between about −0.3 and about 3.0, more preferably between about −0.2 and about 2.0. 
     
     
         3 . A method according to  claim 1 , wherein the electroplating bath has a chloride ion concentration comprised between about 0.1 ppm and about 10 ppm, preferably between about 0.5 ppm and about 8 ppm, more preferably between about 1 ppm and about 5 ppm, even more preferably between about 1 ppm and about 3 ppm, still more preferably between about 1.5 ppm and about 2.5 ppm, most preferably between about 1.8 ppm and about 2.2 ppm. 
     
     
         4 . A method according to  claim 1 , wherein the substrate is provided with at least one feature opening, preferably selected from the group of trenches and vias, wherein said feature opening has a width below about 100 nm, preferably below about 70 nm, more preferably below about 50 nm, even more preferably below about 35 nm. 
     
     
         5 . A method according to  claim 1 , wherein the substrate is provided with a copper seed having a thickness below about 60 nm, preferably below about 50 nm, more preferably below about 30 nm, even more preferably below about 20 nm, still more preferably below about 10 nm, most preferably below about 8 nm. 
     
     
         6 . A method according to  claim 5 , wherein the electroplating bath has an acid concentration comprised between about 0.05% and about 1%, preferably between about 0.05% and about 0.7%, more preferably between about 0.05% and about 0.5%, even more preferably between about 0.05% and about 0.3%, most preferably between about 0.05% and about 0.15% per volume of said electroplating bath. 
     
     
         7 . A method according to  claim 5 , wherein the electroplating bath comprises sulfuric acid, preferably in a concentration comprised between about 10 mmol·l −1  and about 200 mmol·l −1 , more preferably between about 10 mmol·l −1  and about 100 mmol·l −1 , even more preferably between about 15 mmol·l −1  and about 50 mmol·l −1 , most preferably between about 15 mmol·l −1  and about 25 mmol·l −1 . 
     
     
         8 . A method according to any of  claim 1 , wherein the substrate is provided with a seed layer made from a seed material not comprising copper; and wherein the seed material preferably comprises ruthenium. 
     
     
         9 . A method according to  claim 8 , wherein the electroplating bath has an acid concentration comprised between about 5% and about 10%, preferably between about 6% and about 9.5%, even more preferably between about 7% and about 9%, most preferably between about 8% and about 9% per volume of said electroplating bath. 
     
     
         10 . A method according to  claim 8 , wherein the electroplating bath comprises sulfuric acid, preferably in a concentration comprised between about 1 mol·l −1  and about 2 mol·l −1 , more preferably between about 1.2 mol·l −1  and about 1.9 mol·l −1 , even more preferably between about 1.4 mol·l −1  and about 1.8 mol·l −1 , most preferably between about 1.6 mol·l −1  and about 1.8 mmol·l −1 . 
     
     
         11 . A method according to  claim 1 , wherein the electroplating bath has a copper ion concentration comprised between about 0.5 mmol·l −1  and about 30 mmol·l −1 , preferably between about 0.5 mmol·l −1  and about 20 mmol·l −1 , more preferably between about 1.0 mmol·l −1  and about 20 mmol·l −1 , even more preferably between about 1.0 mmol·l −1  and about 10 mmol·l −1 . 
     
     
         12 . A method according to  claim 1 , wherein the electroplating bath further comprises an organic additive system comprising a suppressor of copper deposition on copper and/or an accelerator of copper deposition on copper. 
     
     
         13 . A method according to  claim 12 , wherein the electroplating bath comprises a suppressor of copper deposition, which is preferably polyethylene glycol, in a concentration comprised between about 20 ppm and about 500 ppm, more preferably between about 50 ppm and about 120 ppm, even more preferably between about 70 ppm and about 115 ppm, still more preferably between about 90 ppm and about 110 ppm; most preferably in a concentration of about 100 ppm; and wherein the electroplating bath comprises an accelerator of copper deposition, which is preferably bis-(sodium sulfopropyl)-disulfide, in a concentration comprised between about 0.02 ppm and about 2 ppm, preferably between about 0.1 ppm and about 1.5 ppm, more preferably between about 0.5 ppm and about 1.3 ppm, most preferably between about 0.7 ppm and about 1.0 ppm. 
     
     
         14 . A method for the preparation of an electroplating bath suitable for electroplating a copper deposit onto a substrate, wherein the method comprises the step of:
 a. providing a concentrate composition comprising a source of copper ion and a source of acid; and   b. diluting said concentrate composition into a solution comprising deionized water, thereby forming an electroplating bath as described in  claim 1 .   
     
     
         15 . The concentrate composition as defined in  claim 14 . 
     
     
         16 . The concentrate composition according to  claim 15 , which further comprises a source of chloride ion, preferably in such an amount as to form an electroplating bath having a chloride ion concentration comprised between about 0.1 ppm and about 10 ppm, preferably between about 0.5 ppm and about 8 ppm, more preferably between about 1 ppm and about 5 ppm, even more preferably between about 1 ppm and about 3 ppm, still more preferably between about 1.5 ppm and about 2.5 ppm, most preferably between about 1.8 ppm and about 2.2 ppm, when said concentrate composition is diluted into a solution comprising deionized water. 
     
     
         17 . The method of use according to  claim 1  for the manufacture of a semiconducting device, preferably a semiconductor integrated circuit (IC) device. 
     
     
         18 . The method of use according to  claim 17  for the manufacture of semiconducting devices features, preferably for the manufacture of interconnections having a width which is preferably below about 100 nm, more preferably below about 70 nm, even more preferably below about 50 nm, most preferably below about 35 nm.