Molecular airborne contaminants (MACs) film removal and wafer surface sustaining system and method

Abstract

A MACs mitigation system includes a MACs film removal sub-system ( 14 ) and a wafer surface sustaining sub-system ( 16 ) for sustaining or maintaining the cleaned surface ( 18 A) of a wafer ( 18 ) in a substantially MACs-free condition for some predetermined period of time, such as the typical amount of time required after MACs film removal to perform a desired measurement on the wafer using a metrology tool ( 12 ). The MACs film removal sub-system can comprise a source ( 14 A) of microwave energy that beneficially both heats and dissociates the chemical constituents of the MACs film. The wafer surface sustaining sub-system can be co-located with a measurement stage portion of the metrology tool, and preferably includes an atmosphere provided by a source ( 20 ) of clean gas.

1 . A molecular airborne contaminates (MACs) mitigation system comprising: 
 a first system for removing a MACs film from a surface of a wafer by directing energy towards the surface; and    a second system for sustaining the surface of the wafer in a substantially MACs-free condition for some predetermined period of time.    
     
     
         2 . A MACs mitigation system as in  claim 1 , where the predetermined period of time is at least equal to the time required after MACs film removal to perform a desired measurement sequence or a series of measurements on the wafer using a metrology tool.  
     
     
         3 . A MACs mitigation system as in  claim 1 , where said first system comprises a source of microwave energy that is directed towards the MACs film.  
     
     
         4 . A MACs mitigation system as in  claim 3 , where the source of microwave energy both heats and dissociates chemical constituents of the MACs film.  
     
     
         5 . A MACs mitigation system as in  claim 1 , where said first system further comprises a source of heated or clean, dry gas that is directed towards the MACs film.  
     
     
         6 . A MACs mitigation system as in  claim 1 , where said first system comprises a source of ultraviolet radiation that is directed towards the MACs film.  
     
     
         7 . A MACs mitigation system as in  claim 1 , where said first system comprises a source of microwave energy that is directed towards the MACs film, and a source of heated or dry, clean gas that is directed towards the MACs film.  
     
     
         8 . A MACs mitigation system as in  claim 1 , where said first system comprises a source of microwave energy that is directed towards the MACs film, and a source of ultraviolet radiation that is directed towards the MACs film.  
     
     
         9 . A MACs mitigation system as in  claim 1 , where said first system comprises a source of microwave energy that is directed towards the MACs film, a source of heated or clean, dry gas that is directed towards the MACs film; and a source of ultraviolet radiation that is directed towards the MACs film.  
     
     
         10 . A MACs mitigation system as in  claim 1 , where said second system is co-located with a measurement stage portion of the metrology tool, and comprises an atmosphere provided by a source of clean gas characterized by a complete or partial absence of at least one of hydrocarbons, water and any other substance capable of promoting the growth of a MACs film on the surface of the substrate.  
     
     
         11 . A MACs mitigation system as in  claim 1 , where said first system and said second system are subject to the same environment.  
     
     
         12 . A metrology system, comprising: 
 a metrology tool; and    a molecular airborne contaminates (MACs) mitigation system comprising a first system for removing a MACs film from a surface of a wafer by directing energy towards the surface and a second system for sustaining the surface of the wafer in a substantially MACs-free condition for some predetermined period of time.    
     
     
         13 . A metrology system as in  claim 12 , where said second system is co-located with a measurement stage portion of said metrology tool and comprises an atmosphere provided by a source of clean gas characterized by a complete or at least partial absence of at least one of hydrocarbons, water and any other substance that is capable of promoting the growth of a MACs film on the surface of the substrate.  
     
     
         14 . A metrology system as in  claim 12 , where said metrology tool comprises an ellipsometer.  
     
     
         15 . A metrology system as in  claim 12 , where said metrology tool comprises a reflectometer.  
     
     
         16 . A molecular airborne contaminates (MACs) mitigation system comprising: 
 a first system for removing a MACs film from a surface of a wafer comprising MACs removal means comprised of directed energy means; and    a second system for sustaining the surface of the wafer in a substantially MACs-free condition for some predetermined period of time at least equal to the time required after MACs film removal to perform a desired measurement on the wafer using a metrology tool.    
     
     
         17 . A MACs mitigation system as in  claim 16 , where said directed energy means comprises a source of RF energy.  
     
     
         18 . A MACs mitigation system as in  claim 16 , where said directed energy means comprises a source of ultraviolet optical energy.  
     
     
         19 . A MACs mitigation system as in  claim 16 , where said directed energy means comprises a jet of heated gas.  
     
     
         20 . A MACs mitigation system as in  claim 16 , where said directed energy means comprises a curtain of heated gas.  
     
     
         21 . A MACs mitigation system as in  claim 16 , further comprising means for cooling said wafer at least during operation of said first system.  
     
     
         22 . A MACs mitigation system as in  claim 16 , where at least one of an entrance to or an exit from said first system comprises a curtain of gas.  
     
     
         23 . A MACs mitigation system as in  claim 16 , further comprising a hot plate that heats the MACs film by conduction via the wafer.  
     
     
         24 . A molecular airborne contaminates (MACs) removal system, comprising a source providing a stream of gas that is directed towards a surface of a wafer for removing a MACs film from the surface.  
     
     
         25 . A MACs removal system as in  claim 24 , where said source provides chemically clean gas.  
     
     
         26 . A MACs removal system as in  claim 24 , where said source provides ozone-enriched gas.  
     
     
         27 . A MACs removal system as in  claim 24 , where said source provides chemically clean gas that is also provided to a MACs film formation inhibiting system.  
     
     
         28 . A MACs removal system as in  claim 24 , where said source provides chemically clean gas and comprises a catalytic converter to remove at least hydrocarbons.  
     
     
         29 . A MACs removal system as in  claim 28 , where heat generated from a catalytic reaction is used to warm the gas.  
     
     
         30 . A MACs removal system as in  claim 24 , where said source comprises a heat exchanger.  
     
     
         31 . A MACs removal system as in  claim 24 , further comprising a heater thermally coupled to a gas flow path for producing a heated gas flow at least for combusting impurities in the gas flow.  
     
     
         32 . A MACs removal system as in  claim 3   1 , further comprising a chiller for reducing the temperature of the heated gas flow for at least one of cooling the wafer and maintaining the wafer at a temperature that is suitable for operation of a metrology tool.  
     
     
         33 . A MACs removal system as in  claim 24 , further comprising an ozone generator for generating an ozone-enriched stream of gas.  
     
     
         34 . A MACs removal system as in  claim 24 , further comprising a MACs film formation inhibiting system for sustaining the surface of the wafer in a substantially MACs-free condition for some predetermined period of time at least equal to the time required after MACs film removal to perform a desired measurement on the wafer using a metrology tool.  
     
     
         35 . A method to inhibit formation of a molecular airborne contaminates (MACs) film on a surface, comprising: removing a MACs film from the surface by directing energy towards the surface; and maintaining the surface in a substantially MACs-free condition for some predetermined period of time during which a procedure is performed on or through the surface.  
     
     
         36 . A method as in  claim 3   5 , where the predetermined period of time is at least equal to the time required after MACs film removal to perform at least one measurement on a wafer using a metrology tool.  
     
     
         37 . A method as in  claim 35 , where removing includes directing microwave energy towards the MACs film.  
     
     
         38 . A method as in  claim 37 , where the microwave energy is selected to both heat the MACs film and dissociate at least one chemical constituent of the MACs film.  
     
     
         39 . A method as in  claim 35 , where removing includes directing at least one of heated gas towards the MACs film, and dry, clean gas towards the MACs film.  
     
     
         40 . A method as in  claim 35 , where removing includes directing ultraviolet radiation towards the MACs film.  
     
     
         41 . A method as in  claim 35 , where removing includes directing microwave energy towards the MACs film, and directing at least one of heated gas, and dry, clean gas towards the MACs film.  
     
     
         42 . A method as in  claim 35 , where removing includes directing microwave energy towards the MACs film, and directing ultraviolet radiation towards the MACs film.  
     
     
         43 . A method as in  claim 35 , where removing includes directing microwave energy towards the MACs film, directing at least one of heated gas, and dry, clean gas towards the MACs film, and directing ultraviolet radiation towards the MACs film.  
     
     
         44 . A method as in  claim 35 , where maintaining occurs at a location associated with a measurement stage portion of a metrology tool, and comprises providing an atmosphere from a source of gas having a complete or at least partial absence of at least one of hydrocarbons, water and any other substance that is capable of promoting the growth of a MACs film on the surface.  
     
     
         45 . A method as in  claim 35 , where removing and maintaining are carried out within the same environment.  
     
     
         46 . A method as in  claim 35 , where said procedure comprises a measurement procedure that is performed on a surface associated with a semiconductor wafer.  
     
     
         47 . A method as in  claim 35 , where said procedure comprises an ellipsometry-based metrology procedure that is performed on or through a surface associated with a semiconductor wafer.  
     
     
         48 . A method as in  claim 35 , where said procedure comprises a reflectometry-based metrology procedure that is performed on or through a surface associated with a semiconductor wafer.