Optical proximity correction
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.