System and method for correcting 3D effects in an alternating phase-shifting mask

A library used for correcting intensity imbalance in an alternating phase-shifting mask, thereby compensating for three dimensional effects, the library comprising:

• a plurality of original sizes for 180 degree phase-shifting regions on the alternating phase-shifting mask;
• a plurality of pre-corrected sizes;
• a plurality of transmission values;
• and
• a plurality of phase values, wherein each original size has a corresponding pre-corrected size, a corresponding transmission value, and a corresponding phase value, and wherein the corresponding transmission value and the corresponding phase value allow a two dimensional simulation for the corresponding pre-corrected size to substantially match a three dimensional simulation for the original size;
• and
• optionally, an optical proximity correction of the phase-shifting mask using phase shifters replaced according to the library such that the optical proximity correction is performed on phase shifters corrected for intensity imbalance.

A method of designing a lithographic mask that corrects for intensity imbalance, the method comprising:

• placing 0 degree phase-shifting regions and 180 degree phase-shifting regions on the lithographic mask;
• accessing a library of pre-corrected shifters, wherein each pre-corrected shifter references a size of an original 180 degree phase-shifting region and matching 3D simulation information;
• replacing any 180 degree phase-shifting region with a pre-corrected shifter if that 180 degree phase-shifting region has a size referenced in the library;
• and
• optionally, performing an optical proximity correction of the lithographic mask using phase shifters replaced according to the library such that the optical proximity correction is performed on phase shifters corrected for intensity imbalance.

A method of performing optical proximity correction (OPC) on a layout for an alternating phase-shifting mask, the method comprising:

• identifying a first phase-shifting region and a second phase-shifting region on the layout, wherein a difference between the first phase-shifting region and the second phase-shifting region is approximately 180 degrees, and wherein the second phase-shifting region creates three dimensional effects on the alternating phase-shifting mask;
• accessing a library of pre-corrected shifters, wherein each pre-corrected shifter references a size of an original 180 degree phase-shifting region and matching simulation information;
• replacing the second phase-shifting region with a pre-corrected shifter if a size of the second phase-shifting region is provided in the library, thereby correcting for an intensity imbalance caused by the three dimensional effects;
• and
• performing the OPC on the pre-corrected shifter.

A computer program product for correcting intensity imbalance in an alternating phase-shifting mask, the computer program product comprising:

• a first set of instructions for determining a first group of 180 degree phase-shifting regions for the alternating phase-shifting mask, the first group of 180 degree phase-shifting regions having a common first size;
• a second set of instructions for performing a three-dimensional (3D) simulation based on the first size;
• a third set of instructions for performing a two-dimensional (2D) simulation based on the first size;
• a fourth set of instructions for altering a transmission and a phase in the 2D simulation until a shape dependent transmission and a shape dependent phase allow the 2D simulation to substantially match the 3D simulation;
• a fifth set of instructions for choosing a modified first size of a 180 degree phase-shifting region using the shape dependent transmission and the shape dependent phase such that a 2D simulation based on the modified first size substantially matches the 3D simulation based on the first size;
• and
• a sixth set of instructions for associating the first size, the modified first size, the shape dependent transmission, and the shape dependent phase;
• and
• optionally, a seventh set of instructions for performing an optical proximity correction of the phase-shifting mask using phase shifters replaced according to the library such that the optical proximity correction is performed on phase shifters corrected for intensity imbalance.

A method of designing a trim mask and an associated phase-shifting mask, wherein the phase-shifting mask is corrected for intensity imbalance, the method comprising:

• placing 0 degree phase-shifting regions and 180 degree phase-shifting regions on the phase-shifting mask;
• accessing a library of pre-corrected shifters, wherein each pre-corrected shifter references a size of an original 180 degree phase-shifting region, at least one transmission, and at least one phase, wherein by using the at least one transmission and the at least one phase, a two-dimensional simulation of the pre-corrected shifter substantially matches a three-dimensional simulation of the original 180 degree phase-shifting region;
• optionally, performing optical proximity correction (OPC) on a feature on the trim mask using the at least one transmission and the at least one phase of an associated 180 degree phase-shifting region;
• and
• extending an area of the associated 180 degree phase-shifting region on the phase-shifting mask to be in operative position with the feature.