Processing for overcoming extreme topography

Abstract

A process for overcoming extreme topographies by first planarizing a cavity in a semiconductor substrate in order to create a planar surface for subsequent lithography processing. As a result of the planarizing process for extreme topographies, subsequent lithography processing is enabled including the deposition of features in close proximity to extreme topographic surfaces (e.g., deep cavities or channels) and, including the deposition of features within a cavity. In a first embodiment, the process for planarizing a cavity in a semiconductor substrate includes the application of dry film resists having high chemical resistance. In a second embodiment, the process for planarizing a cavity includes the filling of cavity using materials such as polymers, spin on glasses, and metallurgy.

1 . A method for planarizing extreme topographies on a surface of a semiconductor substrate including at least one deep cavity or channel, said method comprising: providing a dry resist film to bridge said cavity or channel to enable patterning on the surface of a substrate.  
     
     
         2 . The method for planarizing extreme topographies as claimed in  claim 1 , further including the steps of: 
 patterning a feature over said dry resist film bridge;    developing said dry resist film pattern feature to produce an overhang structure including an opening; and,    depositing a material on a lower surface of said cavity or channel through said opening.    
     
     
         3 . The method for planarizing extreme topographies as claimed in  claim 2 , wherein a feature size of said deposited material is defined by a width of said overhang structure.  
     
     
         4 . A method for fabricating a liftoff structure in a semiconductor substrate having a deep cavity or channel, said method comprising: 
 a. providing a dry resist film to bridge said cavity or channel to enable patterning on the surface of said substrate;    b. patterning a feature over said dry resist film bridge;    c. developing said dry resist film pattern feature to produce an overhang structure including an opening; and,    d. depositing a material on a lower surface of said deep cavity or channel, wherein a feature size of said deposited material is defined by a width of said opening.    
     
     
         5 . A method for planarizing extreme topographies on a surface of a semiconductor substrate including at least one deep cavity or channel, said method comprising providing a planarizing material atop said surface including filling said at least one deep cavity or channel with said planarizing material to produce a planarized surface.  
     
     
         6 . The method for planarizing extreme topographies as claimed in  claim 5 , further including the step of forming a liftoff structure including the steps of: 
 patterning a feature over said filled at least one cavity or channel using a mask structure;    etching away the planarizing fill material from said cavity or channel according to said patterned feature to produce an overhang structure including an opening atop said cavity or channel; and,    depositing a material on a lower surface of said cavity or channel through said opening.    
     
     
         7 . The method for planarizing extreme topographies as claimed in  claim 6 , wherein said etching enables deposition of a material on sidewalls of said cavity or channel.  
     
     
         8 . The method for planarizing extreme topographies as claimed in  claim 5 , wherein said material is a polymer.  
     
     
         9 . The method for planarizing extreme topographies as claimed in  claim 5 , wherein said material is a spin on glass.  
     
     
         10 . The method for planarizing extreme topographies as claimed in  claim 5 , wherein said material is a metal.  
     
     
         11 . The method for planarizing extreme topographies as claimed in  claim 5 , wherein said step of filling said at least one deep cavity or channel with said planarizing material includes implementing a screening technique.  
     
     
         12 . The method for planarizing extreme topographies as claimed in  claim 5 , wherein said step of filling said at least one deep cavity or channel with said planarizing material includes implementing a molten solder screening technique.  
     
     
         13 . A method for planarizing extreme topographies on a surface of a semiconductor substrate including at least one deep cavity or channel, said method comprising providing an electroplated a material atop said surface and filling said at least one cavity or channel to produce a planarized surface with a chemical mechanical polish (CMP) step.  
     
     
         14 . The method for planarizing extreme topographies as claimed in  claim 13 , further including the steps of: 
 patterning a feature over said filled at least one cavity or channel using a mask structure;    etching away the planarizing fill material from said cavity or channel according to said patterned feature to produce an overhang structure including an opening atop said deep cavity or channel; and,    depositing a material on a lower surface of said cavity or channel through said opening.    
     
     
         15 . The method for planarizing extreme topographies as claimed in  claim 13 , wherein said etching enables deposition of a material on sidewalls of said cavity or channel.  
     
     
         16 . The method for planarizing extreme topographies as claimed in  claim 13 , wherein said electroplated material includes a metal.  
     
     
         17 . A method for planarizing extreme topographies on a surface of a semiconductor substrate including at least one deep cavity or channel, said method comprising providing an electrolessly plated material atop said surface and filling said at least one cavity to produce a planarized surface without need for a chemical mechanical polish (CMP) step.  
     
     
         18 . The method for planarizing extreme topographies as claimed in  claim 17 , further including the step of forming a liftoff structure including the steps of: 
 patterning a feature over said filled at least one cavity or channel using a mask structure;    etching away the planarizing fill material from said cavity or channel according to said patterned feature to produce an overhang structure including an opening atop said deep cavity or channel; and,    depositing a material on a lower surface of said cavity or channel through said opening.    
     
     
         19 . The method for planarizing extreme topographies as claimed in  claim 17 , wherein said electrolessly plated material includes a metal.  
     
     
         20 . A method for forming an optical bench in a semiconductor substrate, said optical bench including optical elements located in at least one deep cavity or channel, said method including steps of: 
 a. providing a planarizing material atop said surface including filling said at least one deep cavity or channel with said planarizing material to produce a planarized surface;    b. patterning a feature over said filled at least one cavity or channel using a mask structure;    c. etching away the planarizing fill material from said cavity or channel according to said patterned feature to produce an overhang structure including an opening atop said deep cavity or channel; and,    d. depositing a material on a surface of said cavity or channel through said opening, wherein said material includes an electrical or mechanical connection to an optical element positioned in said cavity.