Method of patterning ultra-small structures

Abstract

We describe a process to produce ultra-small structures of between ones of nanometers to hundreds of micrometers in size, in which the structures are compact, nonporous and exhibit smooth vertical surfaces. Such processing is accomplished with pulsed electroplating techniques using ultra-short pulses in a controlled and predictable manner.

1 . A method of patterning ultra-small structures on a surface, comprising: 
 providing a conductive layer;    depositing a mask layer on said conductive layer;    defining a pattern in said mask layer; and    growing said ultra-small structures on said surface in a pulse-electroplating process.    
     
     
         2 . The method of  claim 1  wherein said ultra-small structures are comprised of a material selected from the group consisting silver (Ag), copper (Cu), aluminum (Al), gold (Au) and platinum (Pt).  
     
     
         3 . The method of  claim 1  wherein said pulse-electroplating process comprises the step of applying a series of voltage pulses comprising at least one positive voltage pulse, wherein each said at least one voltage pulse is between 1.5 and 12 volts, and each said at least one voltage pulse lasts for less than 1 microsecond.  
     
     
         4 . The method of  claim 3  wherein each said at least one voltage pulse is for a period of less than 500 ns.  
     
     
         5 . The method of  claim 3  further comprising: 
 after said step of applying, resting for a rest period of at least 1 microsecond, and then repeating said applying step.    
     
     
         6 . The method of  claim 5  wherein the rest period is between 1 microsecond and 500 ms.  
     
     
         7 . The method of  claim 1  wherein said mask layer is comprised of photoresist.  
     
     
         8 . The method of  claim 1  wherein said conductive layer is comprised of carbon.  
     
     
         9 . The method of  claim 1  wherein said conductive layer is comprised of metal.  
     
     
         10 . The method of  claim 1  wherein said conductive layer is comprised of a semiconducting material.  
     
     
         11 . The method of  claim 1  wherein said conductive layer is comprised of a transparent conductor such as indium tin oxide (ITO).  
     
     
         12 . The method of  claim 1  wherein said conductive layer is a conductive polymer.  
     
     
         13 . The method of  claim 1  wherein said conductive layer is a non-metallic conductor such as an ionic conductor, sodium chloride (NaCl).  
     
     
         14 . The method of  claim 3  wherein the series of voltage pulses includes at least one negative voltage pulse.  
     
     
         15 . A method for patterning ultra-small features on a surface comprising: 
 providing a conductive layer on said surface;    depositing a layer of photoresist on said conductive layer;    defining a pattern in said photoresist layer; and    growing said ultra-small structures on said surface in a pulse-electroplating process.    
     
     
         16 . The method of  claim 15  wherein said conductive layer is comprised of carbon.  
     
     
         17 . The method of  claim 15  wherein said conductive layer is comprised of metal.  
     
     
         18 . The method of  claim 15  wherein said pulse-electroplating process includes a step of applying a series of voltage pulses comprising at least one positive voltage pulse, wherein each said at least one voltage pulse lasts for less than 1 microsecond.  
     
     
         19 . The method of  claim 18  wherein each said at least one voltage pulse period is less than 500 ms.  
     
     
         20 . The method of  claim 18  wherein said pulse-electroplating process includes 
 after said step of applying, resting for a rest period of at least 1 microsecond, and then repeating said applying step.    
     
     
         21 . The method of  claim 18  wherein each said at least one voltage pulse is between 1.5 and 12 volts.  
     
     
         22 . The method of  claim 18  wherein the series of voltage pulses further comprises at least one negative voltage pulse.  
     
     
         23 . A method for patterning ultra-small features on a surface comprising: 
 providing a surface having a carbon layer thereon;    depositing a mask layer on said carbon layer;    defining a pattern in said mask layer; and    growing said ultra-small structures on said surface in a pulse-electroplating process.    
     
     
         24 . The method of  claim 23  wherein said ultra-small structures are comprised of a material selected from the group consisting of silver (Ag), copper (Cu), aluminum (Al), gold (Au) and platinum (Pt).  
     
     
         25 . The method of  claim 23  wherein said pulse-electroplating process comprises the step of applying a series of voltage pulses comprising at least one positive voltage pulse, wherein each said at least one voltage pulse is between 1.5 and 12 volts, and each said at least one voltage pulse lasts for less than 1 microsecond.  
     
     
         26 . The method of  claim 25  wherein each said at least one voltage pulse is for a period of less than 500 ns.  
     
     
         27 . The method of  claim 26  further comprising: 
 after said step of applying, resting for a rest period of at least 1 microsecond, and then repeating said applying step.    
     
     
         28 . The method of  claim 27  wherein said rest period is 1 microsecond to 500 ms.  
     
     
         29 . The method of  claim 23  wherein said mask layer is comprised of photoresist.  
     
     
         30 . The method of  claim 25 , wherein the series of voltage pulses further comprises at least one negative voltage pulse.  
     
     
         31 . A method for patterning ultra-small features on a surface comprising: 
 providing said surface with a nickel (Ni) layer;    depositing a silver (Ag) layer on said nickel layer;    depositing a mask layer on said silver layer;    defining a pattern in said mask layer; and    growing said ultra-small structures on said surface in a pulse-electroplating process.    
     
     
         32 . The method of  claim 31  wherein said pulse-electroplating process comprises the step of applying a series of voltage pulses comprising at least one positive voltage pulse, wherein each said at least one pulse is between 1.5 and 12 volts, and each said at least one pulse lasts for less than 1 microsecond.  
     
     
         33 . The method of  claim 31  further comprising: 
 after said step of applying, resting for a rest period of at least 1 microsecond, and then repeating said applying step.    
     
     
         34 . The method of  claim 33  wherein said rest period is 1 microsecond to 500 ms.  
     
     
         35 . The method of  claim 30  wherein said mask layer is comprised of photoresist.  
     
     
         36 . The method of  claim 32  wherein said series of voltage pulses further comprises at least one negative voltage pulse.  
     
     
         37 . A method for patterning ultra-small features on a surface comprising: 
 providing said surface with a nickel (Ni) layer;    depositing a silver (Ag) layer on said nickel layer;    depositing a mask layer on said silver layer;    defining a pattern in said mask layer; and    growing said ultra-small structures on said surface in a pulse-electroplating process that uses ultra-short pulses, wherein said pulse-electroplating process comprises the step of applying a series of voltage pulses comprising at least one ultra-short positive voltage pulse and at least one ultra-short negative voltage pulse, wherein each said at least one pulse is between 1.5 and 12 volts; and, after said step of applying, resting for a rest period of at least 1 microsecond, and then repeating said applying step.