Optical proximity correction

Abstract

Method for utilizing halftoning structures to manipulate the relative magnitudes of diffraction orders to ultimately construct the desired projected-image. At the resolution limit of the mask maker, this is especially useful for converting strongly shifted, no-0 th -diffraction-order, equal-line-and-space chromeless phase edges to weak phase-shifters that have some 0 th order. Halftoning creates an imbalance in the electric field between the shifted regions, and therefore results in the introduction of the 0 th diffraction order.

1. A device manufacturing method comprising the steps of:
 (a) providing a substrate that is at least partially covered by a layer of radiation-sensitive material;  
 (b) providing a projection beam of radiation using a radiation system;  
 (c) using a pattern on a mask to endow the projection beam with a pattern in its cross-section;  
 (d) projecting the patterned beam of radiation onto a target portion of the layer of radiation-sensitive material, wherein, the step (c): 
 use is made of a phase-shifting mask comprising at least one unattenuated, halftoned, phase-shift feature;  
 the mask is off-axis illuminated by the radiation system.  
 
 
     
     
       2. A device manufactured using a method according to  claim 1 . 
     
     
       3. A device manufacturing method comprising the steps of:
 (a) providing a substrate that is at least partially covered by a layer of radiation-sensitive material;  
 (b) providing a projection beam of radiation using a radiation system;  
 (c) using a pattern on a mask to endow the projection beam with a pattern in its cross-section;  
 (d) projecting the patterned beam of radiation onto a target portion of the layer of radiation-sensitive material, wherein, in step (c): 
 use is made of a phase-shifting mask comprising at least one feature, wherein said at least one feature includes halftoned, phase-shifted, transparent features; and  
 the mask is off-axis illuminated by the radiation system.  
 
 
     
     
       4. A device manufactured using a method according to  claim 3 . 
     
     
       5. A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to generate at least one file corresponding to a phase shifting mask capable of transferring an image including 0 th  diffraction order and ±1 st  diffraction orders, onto a material, said generation of said file comprising the step of:
 generating a phase-shifting mask comprising at least one unattenuated, halftoned, phase-shift feature;  
 said phase-shifting mask being utilized in conjunction with off-axis illumination such that radiation traverses said mask and impinges on said material.  
 
     
     
       6. A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to generate at least one file corresponding to a phase shifting mask capable of transferring an image, including 0 th  diffraction order and ±1 st  diffraction orders, onto a material, said generation of said file comprising the step of:
 generating a phase-shifting mask comprising at least one feature, wherein said at least one feature includes halftoned, phase-shifted, transparent features; and  
 said phase-shifting mask being utilized with off-axis illumination such that radiation passes through said mask onto said material.  
 
     
     
       7. The computer program product of  claim 6 , wherein said at least one feature further includes semi-transparent features. 
     
     
       8. The computer program product of  claim 6 , wherein said at least one feature further includes opaque features. 
     
     
       9. A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to generate at least one file corresponding to a mask capable of transferring an image onto a material, said generation of said file comprising the step of:
 generating a phase-shifting mask comprising at least two unattenuated, halftoned, phase-shift features having a width w, said features separated by a width substantially equal to w,  
 wherein said mask provides an image including 0 th  diffraction order and ±1 st  diffraction orders, when illuminated.  
 
     
     
       10. The computer program of  claim 9 , wherein a focus-exposure process window for maintaining a predetermined resist line-width sizing of said mask is substantially common to an attenuated, phase-shift mask of a similar pitch. 
     
     
       11. A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for directing the computer to generate at least one file corresponding to a mask capable of transferring an image onto a material, said generation of said file comprising the step of:
 generating a phase-shifting mask comprising at least two halftoned, phase-shifted, transparent features having a width w, said features separated by a width substantially equal to w,  
 wherein said mask provides an image including 0 th  diffraction order and ±1 st  diffraction orders, when illuminated.  
 
     
     
       12. The computer program of  claim 11 , wherein said at least two features further include semi-transparent features. 
     
     
       13. The computer program of  claim 11 , wherein said at least two features further include opaque features. 
     
     
       14. The computer program of  claim 11 , wherein a focus-exposure process window for maintaining a predetermined resist line-width sizing of said mask is substantially common to an attenuated, phase-shift mask of a similar pitch. 
     
     
       15. A method of designing a phase- shifting mask for transferring an image onto a material, said image including first features having a first pitch and second features having a second pitch different than said first pitch, said method comprising the step of:      modifying in said mask at least one of said first and second features to include at least one unattenuated, halftoned phase - shift feature that emulates an arbitrary percentage transmission between  6   %  and  100   % , whereby said first and second features in said mask emulate different percentage transmissions such that said first and second features share a common exposure latitude and a corresponding depth of focus.     
     
     
       16. A method according to  claim 15  wherein at least one of said first and second features comprise an equal line/space chromeless pattern and said step of modifying is carried out on said equal line/space chromeless pattern such that said pattern produces a  0   th    order having a non - zero amplitude when illuminated.   
     
     
       17. A method according to  claim 15 , wherein said step of modifying is carried out such that the modified features produce a diffraction pattern and aerial image corresponding to a partially transparent, attenuated phase- shaft mask, having an arbitrary percentage transmission.   
     
     
       18. A method according to  claim 15 , wherein said unattenuated, halftoned, phase- shift feature is a primary feature.   
     
     
       19. A method according to  claim 15 , wherein said unattenuated, halftoned, phase- shift feature is an assist feature.   
     
     
       20. A method of fabricating a phase- shifting mask for transferring an image onto a material, the method comprising designing said mask according to the method of    claim 1   , and fabricating a mask according to the design.   
     
     
       21. A device manufacturing method comprising the steps of:
   providing a substrate that is at least partially covered by a layer of radiation - sensitive material;        providing a projection beam of radiation using a radiation system;        using a pattern on a mask to endow the projection beam with a pattern in its cross - section; and        projecting the patterned beam of radiation onto a target portion of the layer of radiation - sensitive material; characterized in that:        said mask includes first features having a first pitch and second features having a second pitch, at least one of said first features having been modified to include at least one unattenuated, halftoned phase - shift feature that emulates an arbitrary percentage transmission between  6   %  and  100   % , whereby said first and second features in said mask emulate different percentage transmissions such that said first and second features share a common exposure latitude and a corresponding depth of focus.     
     
     
       22. A device manufacturing method according to  claim 21 , wherein said mask is off- axis illuminated by said radiation system.   
     
     
       23. A device manufacturing method according to  claim 21 , wherein at least one of said first and second features comprise an equal line/space chromeless pattern and said step of modifying is carried out on said equal line/space chromeless pattern such that said pattern produces a  0   th    order having a non - zero amplitude when illuminated.   
     
     
       24. A device manufacturing method according to  claim 21 , wherein said step of modifying is carried out such that the modified features produce a diffraction pattern and aerial image corresponding to a partially transparent, attenuated phase- shaft mask, having an arbitrary percentage transmission.   
     
     
       25. A device manufacturing method according to  claim 21 , wherein said unattenuated, halftoned, phase- shift feature is a primary feature.   
     
     
       26. A device manufacturing method according to  claim 21 , wherein said unattenuated, halftoned, phase- shift feature is an assist feature.   
     
     
       27. A computer program product for controlling a computer comprising a recording medium readable by the computer, means recorded on the recording medium for the directing the computer to generate at least one file corresponding to a phase- shift mask for transferring an image onto a material, said image including first features having a first pitch and second features having a second pitch different than said first pitch, said generation of said file comprising the step of:      modifying in said mask at least one of said first and second features to include at least one unattenuated, halftoned phase - shift feature that emulates an arbitrary percentage transmission between  6   %  and  100   %,      whereby said first and second features in said mask emulate different percentage transmissions such that said first and second features share a common exposure latitude and a corresponding depth of focus.     
     
     
       28. The computer program product of  claim 27 , wherein at least one of said first and second features comprise an equal line/space chromeless pattern and said step of modifying is carried out on said equal line/space chromeless pattern such that said pattern produces a  0   th    order having a non - zero amplitude when illuminated.   
     
     
       29. The computer program product of  claim 27 , wherein said step of modifying is carried out such that the modified features produce a diffraction pattern and aerial image corresponding to a partially transparent, attenuated phase- shaft mask, having an arbitrary percentage transmission.   
     
     
       30. The computer program product of  claim 27 , wherein said unattenuated, halftoned, phase- shift feature is a primary feature.   
     
     
       31. The computer program product of  claim 27 , wherein said unattenuated, halftoned, phase- shift feature is an assist feature.