Method and system for determining a charged particle beam exposure for a local pattern density
Methods and systems for exposing a desired shape in an area on a surface using a charged particle beam system include determining a local pattern density for the area, based on an original set of exposure information. A pre-proximity effect correction (PEC) maximum dose for the local pattern density is determined, based on a pre-determined target post-PEC maximum dose. The pre-PEC maximum dose may be calculated near an edge of the desired shape. Methods also include modifying the original set of exposure information with the pre-PEC maximum dose to create a modified set of exposure information.
1. A system for exposing a pattern in an area on a surface using a charged particle beam system, the system comprising:
a computer processor configured to determine a local pattern density for the area, based on an original set of exposure information;
a computer processor configured to determine a pre-proximity effect correction (PEC) maximum dose for the local pattern density, based on a pre-determined target post-PEC maximum dose; and
a computer processor configured to modify the original set of exposure information with the pre-PEC maximum dose to create a modified set of exposure information.
2. The system of claim 1 , wherein the pre-determined target post-PEC maximum dose is based on a maximum write time.
3. The system of claim 1 , wherein the modified set of exposure information is refined by PEC resulting in adjusted dosages that are less than the pre-determined target post-PEC maximum dose.
4. The system of claim 1 , further comprising a computer processor configured to determine an artificial background dose for the area, wherein the artificial background dose comprises an additional pattern with a sub-threshold exposure, and wherein the additional pattern is combined with the modified set of exposure information.
5. The system of claim 4 , further comprising a computer processor configured to calculate a backscatter for the area, based on the original set of exposure information, wherein in the area for which the calculated backscatter is less than a pre-determined threshold, the artificial background dose is a difference between the pre-determined threshold and the calculated backscatter.
6. The system of claim 4 , wherein the system is configured to perform a mask exposure inline with one or more steps selected from the group consisting of determining the local pattern density, determining the pre-PEC maximum dose, determining the artificial background dose, and creating the modified set of exposure information.
7. A system for exposing a desired shape in an area on a surface using a charged particle beam system, the system comprising:
a computer processor configured to determine a local pattern density for the area, based on an original set of exposure information;
a computer processor configured to determine a pre-proximity effect correction (PEC) maximum dose for the local pattern density, based on a pre-determined target post-PEC maximum dose, wherein the pre-PEC maximum dose is calculated near an edge of the desired shape; and
a computer processor configured to modify the original set of exposure information with the pre-PEC maximum dose to create a modified set of exposure information.
8. The system of claim 7 , wherein the pre-determined target post-PEC maximum dose is based on a maximum write time.
9. The system of claim 7 , wherein the modified set of exposure information is refined by PEC resulting in adjusted dosages that are less than the pre-determined target post-PEC maximum dose.
10. The system of claim 7 , wherein a portion of a width of the desired shape exceeds a pre-determined width.
11. The system of claim 7 , wherein at a location where a width of a portion of the desired shape is below a pre-determined width, the pre-PEC maximum dose is calculated near a center of the desired shape.
12. The system of claim 7 , further comprising a computer processor configured to calculate a backscatter for a sub area of the area, based on the local pattern density for the area.
13. The system of claim 12 , wherein the computer processor configured to calculate the backscatter for the sub area of the area is configured to increase a dosage for at least one pixel in a plurality of pixels in the sub area, in a location where the backscatter of the sub area is below a pre-determined threshold, thereby increasing the backscatter of the sub area.
14. The system of claim 13 , wherein the dosage for the at least one pixel in the plurality of pixels in the sub area is increased so that the backscatter is increased to a pre-determined value.
15. The system of claim 13 , wherein the dosage for the at least one pixel in the plurality of pixels in the sub area is increased only if the at least one pixel is more than a pre-determined distance from the edge of the desired shape in the area on the surface.
16. The system of claim 13 , wherein the increased dosage of the at least one pixel in the plurality of pixels in the sub area is applied closer than a pre-determined distance from an inner edge of the desired shape in the area on the surface.
17. The system of claim 13 , wherein the increase in the dosage comprises an artificial background dose.