Method for applying metal features onto metallized layers using electrochemical deposition using acid treatment

Abstract

The present invention is directed to a process for producing structures containing metallized features for use in microelectronic workpieces. The process treats a barrier layer to promote the adhesion between the barrier layer and the metallized feature. Suitable means for promoting adhesion between barrier layers and metallized features according to the invention include an acid treatment of the barrier layer, an electrolytic treatment of the barrier layer, or deposition of a bonding layer between the barrier layer and metallized feature. The present invention thus modifies an exterior surface of a barrier layer making it more suitable for electrodeposition of metal on a barrier, thus eliminating the need for a PVD or CVD seed layer deposition process.

1 . A method for forming a metallized feature on a surface of a microelectronic workpiece comprising: 
 providing a workpiece having a metallized layer;    contacting a surface of the metallized layer with an inorganic acid solution in the absence of electroplating power to form an inorganic acid-treated surface without depositing metal onto the inorganic acid treated surface, the inorganic acid content of the inorganic acid solution being less than about 5 wt %; and    electrochemically forming a metallized feature on the inorganic acid-treated surface of the metallized layer.    
   
   
       2 . The method of  claim 1 , wherein the step of electrochemically forming a metallized feature comprises: 
 electrochemically forming a seed layer on the inorganic acid-treated surface of the metallized layer.    
   
   
       3 . The method of  claim 1 , wherein the step of electrochemically forming a metallized feature on the inorganic acid-treated surface of the metallized layer comprises electrochemically depositing copper on the inorganic acid-treated surface of the metallized layer.  
   
   
       4 . The method of  claim 1 , wherein the step of electrochemically forming a metallized feature on the inorganic acid-treated surface of the metallized layer comprises electrochemically depositing a copper alloy on the inorganic acid-treated metallized layer.  
   
   
       5 . The method of  claim 4 , wherein the copper alloy includes copper as a first metal and a second metal selected from the group consisting of chromium, nickel, cobalt, zinc, aluminum, boron, magnesium, and cerium.  
   
   
       6 . The method of  claim 1 , wherein the step of electrochemically forming a metallized feature on the inorganic acid-treated surface of the metallized layer comprises electrochemically depositing ruthenium on the inorganic acid-treated surface of the metallized layer.  
   
   
       7 . The method of  claim 1 , wherein the inorganic acid solution used in the contacting step comprises nitric acid.  
   
   
       8 . The method of  claim 1 , wherein the inorganic acid solution is an aqueous solution containing less than about 3 wt % acid.  
   
   
       9 . The method of  claim 1 , wherein the inorganic acid solution used in the contacting step comprises hydrofluoric acid.  
   
   
       10 . The method of  claim 1 , wherein the inorganic acid solution used in the contacting step comprises nitric acid and hydrofluoric acid.  
   
   
       11 . The method of  claim 1 , further comprising the step of rinsing the surface of the microelectronic workpiece carrying the inorganic acid-treated metallized layer before electrochemically forming the metallized feature thereon.  
   
   
       12 . The method of  claim 11 , further comprising rinsing and thermally treating the surface of the microelectronic workpiece carrying the inorganic acid-treated metallized layer and electrochemically formed metallized feature.  
   
   
       13 . The method of  claim 11 , wherein the step of electrochemically forming a metallized feature is carried out using an electrolytic process.  
   
   
       14 . The method of  claim 1 , wherein the inorganic acid is a strong inorganic acid.  
   
   
       15 . The method of  claim 1 , wherein the step of electrochemically forming a metallized feature comprises: 
 contacting the inorganic acid-treated surface of the metallized layer with an electroplating solution including a source of metal ions as a principal metal species to be deposited during electroplating and providing electroplating power to electroplate the principal metal species onto the inorganic acid-treated surface of the metallized layer.    
   
   
       16 . The method of  claim 15 , wherein the electroplating solution comprises a metal ion complexing agent.  
   
   
       17 . The method of  claim 16 , wherein the principal metal species comprises copper, and the metal ion complexing agent is selected from the group consisting of ethylene diamine, ethylene diamine tetraacetic acid, and a polycarboxylic acid.  
   
   
       18 . The method of  claim 17 , wherein the complexing agent is ethylene diamine.  
   
   
       19 . The method of  claim 17 , wherein the complexing agent is citric acid.  
   
   
       20 . The method of  claim 17 , wherein the complexing agent is ethylene diamine tetraacetic acid.  
   
   
       21 . The method of  claim 15 , wherein the principal metal species comprises copper, and the electroplating solution further comprises boric acid.  
   
   
       22 . The method of  claim 15 , wherein the source of metal ions is selected from the group consisting of copper sulfate, copper gluconate, copper cyanide, copper sulfamate, copper chloride, copper citrate, copper fluoroborate, copper pyrophosphate, and combinations thereof.  
   
   
       23 . The method of  claim 15 , wherein the principal metal species comprises copper, and the electroplating solution further comprises boric acid and a complexing agent selected from the group consisting of ethylene diamine, ethylene tetraacetic acid, and a polycarboxylic acid.  
   
   
       24 . The method of  claim 15 , wherein the electroplating power has a current density in the range of about 20-50 mA/cm 2 .  
   
   
       25 . The method of  claim 15 , wherein the electroplating power has a pulse waveform.  
   
   
       26 . The method of  claim 15 , wherein the electroplating power has a current density in the range of about 20-50 mA/cm 2  and a pulse waveform.  
   
   
       27 . A process for applying a metal structure to a workpiece comprising: 
 providing a workpiece having a metallized layer;    contacting a surface of the metallized layer with an inorganic acid solution in the absence of electroplating power to form an inorganic acid-treated surface without depositing metal onto the inorganic acid treated surface;    contacting the acid-treated metallized layer with an electroplating bath in the presence of electroplating power to electroplate a metal species onto the acid-treated surface to form a composite layer composed of the acid-treated metallized layer and the electroplated metal species; and    electrochemically depositing additional metal onto the composite layer.    
   
   
       28 . A method for forming a copper feature on a surface of a microelectronic workpiece comprising: 
 providing a workpiece having a metallized layer;    contacting a surface of the metallized layer with an inorganic acid solution in the absence of electroplating power to form an inorganic acid-treated surface without depositing metal onto the inorganic acid treated surface, the inorganic acid content of the inorganic acid solution being less than about 5 wt %; and    electrochemically forming a copper feature on the inorganic acid-treated surface of the metallized layer.    
   
   
       29 . The method of  claim 28 , wherein the inorganic acid solution is an aqueous solution containing less than about 3 wt % acid.  
   
   
       30 . The method of  claim 28 , wherein the inorganic acid is a strong inorganic acid.  
   
   
       31 . The method of  claim 28 , wherein the step of electrochemically forming a copper feature comprises: 
 contacting the inorganic acid-treated surface of the metallized layer with an electroplating solution including a source of metal ions as a principal metal species to be deposited during electroplating and providing electroplating power to electroplate the principal metal species onto the inorganic acid-treated surface of the metallized layer.    
   
   
       32 . The method of  claim 31 , wherein the electroplating solution comprises a metal ion complexing agent.  
   
   
       33 . The method of  claim 32 , wherein the metal ion complexing agent is selected from the group consisting of ethylene diamine, ethylene diamine tetraacetic acid, and a polycarboxylic acid.  
   
   
       34 . The method of  claim 33 , wherein the complexing agent is ethylene diamine.  
   
   
       35 . The method of  claim 33 , wherein the complexing agent is citric acid.  
   
   
       36 . The method of  claim 33 , wherein the complexing agent is ethylene diamine tetraacetic acid.  
   
   
       37 . The method of  claim 31 , wherein the electroplating solution further comprises boric acid.  
   
   
       38 . The method of  claim 31 , wherein the source of metal ions is selected from the group consisting of copper sulfate, copper gluconate, sodium copper cyanide, copper sulfamate, copper chloride, copper citrate, copper fluoroborate, copper pyrophosphate, and combinations thereof.  
   
   
       39 . The method of  claim 32 , wherein the electroplating solution further comprises boric acid and a complexing agent selected from the group consisting of ethylene diamine, ethylene tetraacetic acid, and a polycarboxylic acid.  
   
   
       40 . The method of  claim 32 , wherein the electroplating power has a current density in the range of about 20-50 mA/cm 2 .  
   
   
       41 . The method of  claim 32 , wherein the electroplating power has a pulse waveform.  
   
   
       42 . The method of  claim 32 , wherein electroplating power has a current density in the range of about 20-50 mA/cm 2  and a pulse waveform.