Extreme ultraviolet soft x-ray projection lithographic method system and lithographic elements

Abstract

The projection lithographic method for producing integrated circuits and forming patterns with extremely small feature dimensions includes an illumination sub-system ( 36 ) for producing and directing an extreme ultraviolet soft x-ray radiation λ from an extreme ultraviolet soft x-ray source ( 38 ); a mask stage ( 22 ) illuminated by the extreme ultraviolet soft x-ray radiation λ produced by illumination stage and the mask stage ( 22 ) includes a pattern when illuminated by radiation λ. A protection sub-system includes reflective multilayer coated Ti doped high purity SiO2 glass defect free surface ( 32 ) and printed media subject wafer which has a radiation sensitive surface.

1. A projection lithographic method for producing integrated circuits with printed feature dimensions less than 100 nm, said method comprising:
 providing an illumination sub-system for producing and directing an extreme ultraviolet soft x-ray radiation λ, said illumination sub-system including an extreme ultraviolet soft x-ray source, providing a mask stage and a mask illuminated by said extreme ultraviolet soft x-ray radiation λ produced by said illumination sub-system for forming a projected lithographic pattern when illuminated by said radiation λ, providing a projection sub-system, providing a wafer stage and an integrated circuit wafer, said integrated circuit wafer having a λ radiation sensitive wafer surface, projecting with said projection sub-system the projected lithographic pattern from said mask onto said radiation sensitive wafer surface, said sub-system comprising a plurality of reflective lithography elements, said lithography elements including a plurality of reflective multilayer coated Ti doped high purity SiO 2  glass substrates with defect free glass surfaces for manipulating said radiation and aid lithographic pattern.  
 
     
     
       2. A method as claimed in  claim 1  wherein said Ti doped SiO 2  glass is inclusion free. 
     
     
       3. A method as claimed in  claim 1  wherein said Ti doped SiO 2  glass substrate surface is an unetched glass surface. 
     
     
       4. A method as claimed in  claim 1  wherein said Ti doped SiO 2  glass is substantially non-transmissive to said extreme ultraviolet soft x-ray radiation λ. 
     
     
       5. A method as claimed in  claim 1  wherein said Ti doped SiO 2  glass substrate contains from 5 to 10 wt. % TiO 2  and has a coefficient of thermal expansion in the range from +30 ppb to −30 ppb at 20° C. 
     
     
       6. A method as claimed in  claim 5  wherein said coefficient is in the range of +10 ppb to −10 ppb at 20° C. 
     
     
       7. A method as claimed in  claim 6  wherein said substrate has a variation in coefficient of thermal expansion ≦15 ppb. 
     
     
       8. A method as claimed in  claim 5  wherein said substrate has a variation in coefficient of thermal expansion ≦15 ppb. 
     
     
       9. A method as claimed in  claim 5 , wherein said Ti doped SiO 2  glass is heated to an operating temperature by said radiation λ and said Ti doped SiO 2  glass has a Ti dopant level such that said glass has a coefficient of thermal expansion at said operating temperature centered about 0. 
     
     
       10. A method as claimed in  claim 1  wherein said substrate has a thermal conductivity K ≦1.40 w/(mx° C.) at 25° C. 
     
     
       11. A method as claimed in  claim 1  wherein said Ti doped SiO 2  glass substrate is heated by said radiation λ, and said projected lithographic pattern on said integrated circuit wafer is substantially unaffected by said heating of said glass substrate. 
     
     
       12. A method as claimed in  claim 1  wherein said reflective multilayer coated Ti doped SiO 2  glass lithography element surface reflects at least 65% of the radiation λ illuminating the reflective lithography element. 
     
     
       13. A method as claimed in  claim 12  wherein said reflective multilayer coated Ti doped SiO 2  glass surface reflects at least 70% of the radiation λ. 
     
     
       14. A method as claimed in  claim 12  wherein said reflective multilayer is directly coated on said Ti doped SiO 2  glass surface. 
     
     
       15. A method as claimed in  claim 1  wherein said reflective lithography elements have a maximum operating temperature and a maximum manufacturing temperature and said Ti doped high purity SiO 2  glass has a crystallization temperature T crystal  which is greater than said maximum operating temperature and said maximum manufacturing temperature. 
     
     
       16. A method as claimed in  claim 15  wherein T crystal  is at least 400° C. higher than said maximum operating temperature and said maximum manufacturing temperature. 
     
     
       17. A method as claimed in  claim 16  wherein T crystal >1100° C. 
     
     
       18. A method as claimed in  claim 1  wherein said reflective lithography elements have a lowest lithography operating temperature and a highest lithography operating temperature, said Ti doped high purity SiO 2  glass free of thermal cycling hysteresis when repeatedly cycled at least a hundred times from said lowest lithography operating temperature to said highest lithography operating temperature. 
     
     
       19. A method as claimed in  claim 1  wherein said Ti doped high purity SiO 2  glass has a birefringence less than 10 nm/cm. 
     
     
       20. A method of making a projection lithographic printing pattern, said method comprising:
 providing an illumination sub-system including an extreme ultraviolet soft x-ray source, providing a mask stage, said mask stage including a reflective mask Ti doped high purity SiO 2  glass mask wafer with a glass mask wafer surface coated with a reflective multilayer coating providing a projection reduction sub-system, said projection reduction sub-system including a plurality of Ti doped high purity SiO 2  glass reflective lithography elements, providing a wafer stage, said wafer stage including a radiation sensitive semiconductor wafer, aligning said illumination sub-system, said mask stage, said projection reduction sub-system and said wafer stage wherein said extreme ultraviolet soft x-ray source illuminates said mask with extreme ultraviolet soft x-ray radiation, said reflective mask reflects said radiation and forms a printing pattern which is reduced and projected by said projection reduction sub-system Ti doped high purity SiO 2  glass reflective lithography elements onto said semiconductor wafer.  
 
     
     
       21. A method as claimed in  claim 20 , wherein providing said illumination sub-system includes providing a plurality of Ti doped high purity SiO 2  glass reflective lithography elements which direct and condense said extreme ultraviolet soft x-ray radiation. 
     
     
       22. A method as claimed in  claim 21 , wherein providing Ti doped high purity SiO 2  glass reflection lithography elements includes providing glass surfaces free of surface figure measurements >0.25 nm rms. 
     
     
       23. A method as claimed in  claim 20 , wherein providing Ti doped high purity SiO 2  glass reflective lithography elements includes providing shaped glass surfaces free of surface figure measurements >0.25 nm rms. 
     
     
       24. A method as claimed in  claim 20 , further comprising, determining an operating temperature of said reflective lithography elements when exposed to said extreme ultraviolet soft x-ray radiation during operation of said method, and providing a reflective lithography elements includes providing lithography elements with Ti doped high purity SiO 2  glass having coefficients of thermal expansion at the operating temperatures of the reflective lithography elements that are centered about 0. 
     
     
       25. A method as claimed in  claim 20 , wherein said Ti doped high purity SiO 2  glass is heated to a raised temperature range by said extreme ultraviolet soft x-ray radiation and said Ti doped high purity SiO 2  glass has a coefficient of thermal expansion for said raised temperature range that is less than 10 ppb and greater than −10 ppb. 
     
     
       26. A method as claimed in  claim 25  wherein said glass has a variation in coefficient of thermal expansion ≦10 ppb. 
     
     
       27. A method as claimed in  claim 20  wherein said Ti doped high purity SiO 2  glass has a thermal conductivity K ≦1.40 w/(mx° C.) at 25° C. 
     
     
       28. A method of making a reflective extreme ultraviolet soft x-ray lithography element said method comprising:
 providing a Ti doped high purity SiO 2  glass substrate free of inclusions and having a shaped element glass surface with surface figure features <0.25 nm rms, mid-spatial frequency roughness <0.20 nm rms, and high spatial frequency roughness <0.10 rms,  
 coating said shaped element glass surface with a reflective multilayer coating with uniform multilayer period thickness controlled to at least 0.1% rms, to form a uniform reflective coating having a reflectivity of at least 65% to extreme ultraviolet soft x-rays.  
 
     
     
       29. A method as claimed in  claim 28 , wherein said lithography element is heated to a raised temperature range by extreme ultraviolet soft x-ray radiation and said Ti doped high purity SiO 2  glass has a coefficient of thermal expansion for said raised temperature range that is less than 10 ppb and greater than −10 ppb and has a variation ≦10 ppb. 
     
     
       30. A method as claimed in  claim 28 , wherein providing a Ti doped high purity SiO 2  glass substrate further includes, providing a high purity Si containing feedstock and a high purity Ti containing feedstock, delivering said high purity Si containing feedstock and said high purity Ti containing feedstock to a conversion site, converting said Si containing feedstock and said Ti containing feedstock into Ti doped SiO 2  soot, consolidating said Ti doped SiO 2  soot into an inclusion fee homogeneous Ti doped high purity SiO 2  glass, forming said glass into a Ti doped high purity SiO 2  glass substrate. 
     
     
       31. A method as claimed in  claim 30 , wherein providing a high purity Si containing feedstock and a high purity Ti containing feedstock includes providing a chlorine-free high purity Si containing feedstock and providing a chlorine-free high purity Ti containing feedstock, converting said chlorine-free feedstocks into chlorine-free Ti doped SiO 2  soot, and consolidating said soot into a chlorine-free Ti doped SiO 2  glass. 
     
     
       32. A method as claimed in  claim 28 , wherein said glass substrate has a Ti dopant weight percent level and providing a Ti doped high purity SiO 2  glass substrate further includes adjusting said Ti dopant weight percent level so that said glass substrate has a coefficient of thermal expansion centered about 0 at an operating temperature of said mask. 
     
     
       33. A reflective extreme ultraviolet soft x-ray lithography element comprising:
 a Ti doped high purity SiO 2  inclusion-free glass having an unetched polished radiation manipulating shaped surface with the surface free of printable surface figure defects that a have a surface figure measurement >0.25 nm rms, said surface having a mid-spatial frequency roughness <0.20 nm rms, and a high-spatial frequency roughness <0.10 nm rms.  
 
     
     
       34. A lithography element as claimed in  claim 33  wherein said glass consists of silicon, titanium, and oxygen. 
     
     
       35. A lithography element as claimed in  claim 33  wherein said glass contains from 5 to 10 wt. % TiO 2  and has a coefficient of thermal expansion in the rage  range from +10 ppb to −10 ppb at 20° C. 
     
     
       36. A lithography element as claimed in  claim 33  wherein said glass is crystal-free. 
     
     
       37. A lithography element as claimed in  claim 33  wherein said glass is free of chlorine. 
     
     
       38. A lithography element as claimed in  claim 33  wherein said glass has an impurity level of less than 10 ppm of alkali and alkaline earth metals and said Ti dopant is homogeneously distributed in said glass. 
     
     
       39. A method of making a reflective extreme ultraviolet soft x-ray lithography element said method comprising:
 providing a high purity Si containing feedstock and a high purity Ti containing feedstock, delivering said high purity Si containing feedstock and said high purity Ti containing feedstock to a conversion site, converting said Si containing feedstock and said Ti containing feedstock into Ti doped SiO 2  soot, consolidating said Ti doped SiO 2  soot into an inclusion free homogeneous Ti doped high purity SiO 2  glass, forming glass into a Ti doped high purity SiO 2  glass preform.  
 
     
     
       40. A method as claimed in  claim 39  further comprising forming said preform into a shaped surface lithography element substrate, measuring a figure and finish of said substrate surface, and coating the substrate surface with an extreme ultraviolet soft x-ray reflective coating. 
     
     
       41. A method as claimed in  claim 39 , wherein providing a high purity Si containing feedstock includes providing a chlorine-free high purity Si containing feedstock and providing a chlorine-free high purity Ti containing feedstock, converting said chlorine-free feedstocks into chlorine-free Ti doped SiO 2  soot, and consolidating said soot into chlorine-free Ti doped SiO 2  glass. 
     
     
       42. A method as claimed in  claim 39 , wherein said glass preform has a Ti dopant weight percent level and providing a Ti doped SiO 2  glass preform further includes adjusting said Ti dopant weight percent level so that said preform has a coefficient of thermal expansion centered about 0 at an operating temperature of said lithography element. 
     
     
       43. A method as claimed in  claim 39 , wherein said glass preform consists of silicon, titanium, and oxygen. 
     
     
       44. A reflective extreme ultraviolet soft x- ray lithography element comprising:      a Ti doped high purity SiO   2    inclusion - free glass having a polished radiation manipulating shaped surface with the surface free of printable surface figure defects that have a surface figure measurement > 0 . 25  nm rms, said surface having a mid - spatial frequency roughness < 0 . 20  nm rms, and a high - spatial frequency roughness < 0 . 10  nm rms.      
     
     
       45. A lithography element as claimed in  claim 44  wherein said glass consists of silicon, titanium, and oxygen.  
     
     
       46. A lithography element as claimed in  claim 44  wherein said glass contains from  5  to  10  wt. %  TiO   2    and has a coefficient of thermal expansion in the range from + 10  ppb to − 10  ppb at  20 ° C.    
     
     
       47. A lithography element as claimed in  claim 44  wherein said glass is crystal- free.    
     
     
       48. A lithography element as claimed in  claim 44  wherein said glass is free of chlorine.  
     
     
       49. A lithography element as claimed in  claim 44  wherein said glass has an impurity level of less than  10  ppm of alkali and alkaline earth metals and said Ti dopant is homogeneously distributed in said glass.