Bath and method for high rate copper deposition

Abstract

A plating bath for electroplating copper on a microelectronic workpiece in a through-mask plating application at a rate of at least 2 μm/min where the bath includes: (a) 50-85 g/L of Cu 2+ ; (b) 50-100 g/L of H 2 SO 4 ; (c) 30-150 ppm of Cl—; (d) a brightener; (e) a wetting agent; (f) optionally a leveler; and (g) water. A process for electroplating copper on a microelectronic workpiece in a through-mask plating application at a rate of at least 2 μm/min where the process includes the steps of: (a) providing the plating bath described above; (b) providing a workpiece which has one or more through-mask openings having a conductive layer at the bottom of the openings; (c) contacting the conductive layer with the plating bath; and (d) providing electroplating power between the conductive layer and an anode disposed in electrical contact with the bath, whereby copper is deposited onto the conductive layer at a rate of at least 2 μm/min.

1 . A plating bath for electroplating copper on a microelectronic workpiece in a through-mask plating application at a rate of at least 2 μm/min, said bath comprising: 
 (a) 50-85 g/L of Cu 2+ ;    (b) 50-100 g/L of H 2 SO 4 ;    (c) 30-150 ppm of Cl—;    (d) a brightener;    (e) a wetting agent; and    (f) water.    
     
     
         2 . The bath of  claim 1 , wherein the source of Cu 2+  is CuSO 4 .5H 2 O.  
     
     
         3 . The bath of  claim 1 , wherein the concentration of Cu 2+  is 60-70 g/L.  
     
     
         4 . The bath of  claim 1 , wherein the concentration of H 2 SO 4  is 75-85 g/L.  
     
     
         5 . The bath of  claim 1 , wherein the source of Cl— is HCl  
     
     
         6 . The bath of  claim 1 , wherein the concentration of Cl— is 60-110 ppm.  
     
     
         7 . The bath of  claim 1 , wherein the concentration of brightener is 2-8 ml/L.  
     
     
         8 . The bath of  claim 1 , wherein the concentration of wetting agent is 2-10 ml/L.  
     
     
         9 . A plating bath for electroplating copper on a microelectronic workpiece in a through-mask plating application at a rate of at least 2 μm/min, said bath comprising: 
 (a) 50-85 g/L of Cu 2+ ;    (b) 50-100 g/L of H 2 SO 4 ;    (c) 30-150 ppm of Cl—;    (d) a brightener;    (e) a wetting agent;    (f) a leveler; and    (g) water.    
     
     
         10 . The bath of  claim 9 , wherein the source of Cu 2+  is CuSO 4 .5H 2 O.  
     
     
         11 . The bath of  claim 9 , wherein the concentration of Cu 2+  is 60-70 g/L.  
     
     
         12 . The bath of  claim 9 , wherein the concentration of H 2 SO 4  is 70-85 g/L.  
     
     
         13 . The bath of  claim 9 , wherein the source of Cl— is HCl.  
     
     
         14 . The bath of  claim 9 , wherein the concentration of Cl— is 60-110 ppm.  
     
     
         15 . The bath of  claim 9 , wherein the concentration of brightener is 2-8 ml/L.  
     
     
         16 . The bath of  claim 9 , wherein the concentration of wetting agent is 2-10 ml/L.  
     
     
         17 . The bath of  claim 9  wherein the concentration of leveler is 1-6 ml/L.  
     
     
         18 . A plating bath for electroplating copper on a microelectronic workpiece through a photoresist mask, said bath comprising: 
 (a) Cu 2+ ;    (b) H 2 SO 4 ;    (c) Cl—;    (d) a brightener;    (e) a wetting agent; and    (f) water,    the bath exhibiting a droplet contact angle with the photoresist of less than 20 degrees.    
     
     
         19 . A plating bath for electroplating copper on a microelectronic workpiece through a photoresist mask, said bath comprising: 
 (a) Cu 2+ ;    (b) H 2 SO 4 ;    (c) Cl—;    (d) a brightener;    (e) a wetting agent; and    (f) water,    (g) the bath exhibiting a surface tension ranging from 45-60 dyne/cm at 20° C.    
     
     
         20 . A process for electroplating copper on a microelectronic workpiece in a through-mask plating application at a rate of at least 2 μm/min, said process comprising: 
 (a) providing a plating bath comprising: 
 (1) 50-85 g/L of Cu 2+ ;  
 (2) 50-100 g/L of H 2 SO 4 ;  
 (3) 30-150 ppm of Cl—;  
 (4) a brightener;  
 (5) a wetting agent; and  
 (6) water;  
   (b) providing a microelectronic workpiece having one or more through-mask openings with a conductive layer at the bottom of said opening;    (c) contacting said conductive layer with said plating bath;    (d) providing electroplating power between said conductive layer and an anode disposed in electrical contact with said bath; and    (e) depositing copper onto said conductive layer at a rate of at least 2 μm/min.    
     
     
         21 . The process of  claim 20 , wherein the current density of said electroplating power is 100-300 mA/cm 2 .  
     
     
         22 . The process of  claim 21 , wherein the current density of said electroplating power is 150-220 mA/cm 2 .  
     
     
         23 . The process of  claim 20 , wherein the waveform of said electroplating power is a DC and a pulse with a 10-50% duty cycle at 50-1000 Hz.  
     
     
         24 . The process of  claim 20 , wherein said workpiece is rotated at a speed of 20-200 revolutions per minute and wherein said bath flows against said workpiece at a flow rate of 1-10 gallons per minute.  
     
     
         25 . The process of  claim 20 , wherein said bath has a temperature of 25-35° C.  
     
     
         26 . The process of  claim 20 , wherein the depositing step further comprising depositing copper to form a deposited feature having a smooth surface morphology.  
     
     
         27 . The process of  claim 20 , wherein the depositing step further comprising depositing copper to form a deposited feature that has a substantially flat surface.  
     
     
         28 . The process of  claim 20 , wherein the depositing step further comprising depositing copper to form a deposited feature that has a thickness variation of less than 10%.  
     
     
         29 . A process for electroplating copper on a microelectronic workpiece in a through-mask plating application at a rate of at least 2 μm/min, said process comprising: 
 (a) providing a plating bath comprising: 
 (1) 50-85 g/L of Cu 2+ ;  
 (2) 50-100 g/L of H 2 SO 4 ;  
 (3) 30-150 ppm of Cl—;  
 (4) a brightener;  
 (5) a wetting agent;  
 (6) a leveler; and  
 (7) water;  
   (b) providing a microelectronic workpiece having one or more through-mask openings with a conductive layer at the bottom of said opening;    (c) contacting said conductive layer with said plating bath;    (d) providing electroplating power between said conductive layer and an anode disposed in electrical contact with said bath; and    (e) depositing copper onto said conductive layer at a rate of at least 2 μm/min.    
     
     
         30 . The process of  claim 29  wherein the current density of said electroplating power is 100-300 mA/cm 2 .  
     
     
         31 . The process of  claim 30  wherein the current density of said electroplating power is 150-220 mA/cm 2 .  
     
     
         32 . The process of  claim 29  wherein the waveform of said electroplating power is a DC and a pulse with a 10-50% duty cycle at 50-1000 Hz.  
     
     
         33 . The process of  claim 29  wherein said workpiece is rotated at a speed of 20-200 revolutions per minute and wherein said bath flows against said workpiece at a flow rate of 1-10 gallons per minute.  
     
     
         34 . The process of  claim 29  wherein said bath has a temperature of 25-35° C.  
     
     
         35 . The process of  claim 30 , wherein the depositing step further comprising depositing copper to form a deposited feature having a smooth surface morphology.  
     
     
         36 . The process of  claim 30 , wherein the depositing step further comprising depositing copper to form a deposited feature that has a substantially flat surface.  
     
     
         37 . The process of  claim 30 , wherein the depositing step further comprising depositing copper to form a deposited feature that has a thickness variation of less than 10%.  
     
     
         38 . A process for forming solder bumps on a microelectronic workpiece, said process comprising: 
 (a) providing a workpiece comprising a silicon wafer, one or more chip pads, and a passivation layer;    (b) applying over said chip pads and said passivation layer a diffusion barrier and a conductive layer;    (c) applying over said conductive layer a photoresist layer and then removing portions of said photoresist layer to create openings in said photoresist layer thereby exposing portions of said conductive layer at the bottom of said openings;    (d) providing a plating bath comprising: 
 (1) 50-85 g/L of Cu 2+ ;  
 (2) 50-100 g/L of H 2 SO 4 ;  
 (3) 30-150 ppm of Cl—;  
 (4) a brightener;  
 (5) a wetting agent; and  
 (6) water;  
   (e) contacting said conductive layer with the plating bath;    (f) providing electroplating power between said conductive layer and an anode disposed in electrical contact with said bath;    (g) depositing copper onto the conductive layer at a rate of at least 2 μm/min;    (h) applying a solder layer over the deposited copper;    (i) removing said photoresist layer and thereafter etching away the exposed portions of said diffusion barrier and said conductive layer; and    (j) reflowing said solder layer.    
     
     
         39 . The process of  claim 38  wherein said plating bath comprises: 
 (a) 60-70 g/L of Cu 2+  wherein the source of Cu 2+  is CuSO 4 .5H 2 O;    (b) 75-85 g/L of H 2 SO 4 ;    (c) 60-110 ppm of Cl— wherein the source of Cl— is HCl;    (d) 2-8 ml/L of a brightener;    (e) 2-10 ml/L of a wetting agent; and    (f) water.    
     
     
         40 . The process of  claim 38  wherein, the plating bath further comprises a leveler.  
     
     
         41 . A process for forming conductive feature employing through-mask plating comprising: 
 (a) providing a microelectronic workpiece, the microelectronic workpiece including a passivation layer;    (b) applying a barrier layer over the passivation layer;    (c) applying a conductive layer over the barrier layer;    (d) applying a masking layer over the conductive layer;    (e) patterning the masking layer to expose portions of the conductive layer;    (f) electroplating copper onto the conductive layer at a rate of at least 2 μm/min by: 
 (1) contacting the conductive layer with a plating bath comprising: 
 a) 50-85 g/L of Cu 2+ ;  
 b) 50-100 g/L of H 2 SO 4 ;  
 c) 30-150 ppm of Cl— 
 d) a brightener;  
 e) a wetting agent; and  
 f) water, and  
 
 (2) providing electroplating power between said conductive layer and an anode disposed in electrical contact with said bath  
   (g) removing the masking layer; and    (h) removing at least portions of the barrier layer and conductive layer exposed by the removal of the masking layer.    
     
     
         42 . The process of  claim 41 , wherein the copper is electroplated onto the conductive layer at a rate of at least 4 μm/min.  
     
     
         43 . The process of  claim 41 , wherein the bath further comprises a leveler.