Method, computer program, apparatus and system providing printing for an illumination mask for three-dimensional images
View Patent ↗A method able to provide illumination source parameters for illumination of a lithographic mask in order to project a three-dimensional image into a resist system. Source intensities of incident beams are determined using a near linear program and responsive to an allowed range of variation. Computer program, apparatus and system are detailed and variations are described.
1. A mask illumination method, comprising:
determining an allowed range of at least one photolithographic process parameter;
determining a plurality of source intensities of a plurality of incident mask illumination beams using a near linear program, where the determined plurality of source intensities fall within said allowed range without causing the projected shape to unacceptably depart from a desired three-dimensional shape,
where the desired three-dimensional shape comprises at least two different cross-section layers; and
illuminating a photolithographic mask using a combination of source illumination parameters for illuminating the lithographic mask with light from a plurality of directions such that the plurality of intensities of incident beams of light provide a process window defined in terms of the allowed range.
2. The method of claim 1 , where said photolithographic process parameters comprise at least one of: exposure time, dose variation, depth variation, wafer height and focal variation.
3. The method of claim 2 , where said exposure time range is determined with respect to a first set of constraints which represent maximum exposure times for fast boundaries and a second set of constraints which represent minimum exposure times for slow boundaries.
4. The method of claim 2 , where said focal variations have nonuniform step sizes.
5. The method of claim 1 , further comprising illuminating a wafer with multiple exposures which may have different illumination parameters.
6. The method of claim 1 , where said plurality of source intensities of incident beams of light include at least one of overlapping source pixels and defined polarization.
7. A non-transitory computer readable medium tangibly embodying a program of machine-readable instructions executable by a digital processing apparatus to perform operations for mask illumination, the operations comprising:
determining an allowed range of at least one photolithographic process parameter;
determining a plurality of source intensities of a plurality of incident mask illumination beams using a near linear program, where the determined plurality of source intensities fall within said allowed range without causing the projected shape to unacceptably depart from a desired three-dimensional shape,
where the desired three-dimensional shape comprises at least two different cross-section layers; and
providing a combination of source illumination parameters for illuminating the lithographic mask with light from a plurality of directions such that the plurality of source intensities of incident beams of light provide a process window defined in terms of the allowed range.
8. The computer readable medium of claim 7 , where said photolithographic process parameters comprise at least one of: exposure time, dose variation, depth variation, wafer height and focal variation.
9. The computer readable medium of claim 8 , where said exposure time range is determined with respect to a first set of constraints which represent maximum exposure times for fast boundaries and a second set of constraints which represent minimum exposure times for slow boundaries.
10. The computer readable medium of claim 8 , where the focal variations have nonuniform step sizes.
11. The computer readable medium of claim 7 , where said plurality of source intensities of incident beams of light include at least one of overlapping source pixels and defined polarization.
12. An apparatus comprising:
a driver configured to determine an allowed range of at least one photolithographic process parameter and to determine a plurality of source intensities of a plurality of incident mask illumination beams using a near linear program, where the determined plurality of source intensities fall within said allowed range without causing the projected shape to unacceptably depart from a desired three-dimensional shape,
where the desired three-dimensional shape comprises at least two different cross-section layers; and
a set of illumination sources, configurable to illuminate a photolithographic mask using a combination of source illumination parameters for illuminating the lithographic mask with light from a plurality of directions such that the plurality of source intensities of incident beams of light provide a process window defined in terms of the allowed range.
13. The apparatus of claim 12 , where said photolithographic process parameters comprise at least one of: exposure time, dose variation, depth variation, wafer height and focal variation.
14. The apparatus of claim 13 , where said exposure time range is determined with respect to a first set of constraints which represent maximum exposure times for fast boundaries and a second set of constraints which represent minimum exposure times for slow boundaries.
15. The apparatus of claim 13 , where said focal variations have nonuniform step sizes.
16. The apparatus of claim 12 , further comprising illuminating a wafer with multiple exposures which may have different illumination parameters.
17. The apparatus of claim 12 , where said plurality of source intensities of incident beams of light include at least one of overlapping source pixels and defined polarization.
18. A system for illuminating a mask comprising:
means for determining an allowed range of at least one photolithographic process parameter;
means for determining a plurality of source intensities of a plurality of incident mask illumination beams using a near linear program, where the determined plurality of source intensities fall within said allowed range without causing the projected shape to unacceptably depart from a desired three-dimensional shape,
where the desired three-dimensional shape comprises at least two different cross-section layers; and
means for illuminating a photolithographic mask using a combination of source illumination parameters for illuminating the lithographic mask with light from a plurality of directions such that the plurality of source intensities of incident beams of light provide a process window defined in terms of said allowed range.
19. The system of claim 18 , where said illuminated mask if further used to illuminate a wafer with multiple exposures which may have different illumination parameters.
20. The system of claim 18 , where said plurality of source intensities of incident beams of light include at least one of overlapping source pixels and defined polarization.