Method and apparatus for providing optical proximity features to a reticle pattern for deep sub-wavelength optical lithography

An apparatus for generating a mask design having optical proximity correction features disposed therein, said apparatus comprising the steps of:

• means for obtaining a desired target pattern having features to be imaged on a substrate;
• means for generating an interference map based on said target pattern, said interference map defining areas of constructive interference and areas of destructive interference between at least one of said features to be imaged and a field area adjacent said at least one feature;
• and
• means for placing assist features in the mask design based on the areas of constructive interference and the areas of destructive interference.

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 files corresponding to a mask for use in an lithographic imaging process, said generation of said files comprising the steps of:

• obtaining a desired target pattern having features to be imaged on a substrate;
• generating an interference map based on said target pattern, said interference map defining areas of constructive interference and areas of destructive interference between at least one of said features to be imaged and a field area adjacent said at least one feature;
• and
• placing assist features in the mask design based on the areas of constructive interference and the areas of destructive interference.

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 an imaging 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), said mask is generated by a process including the steps of:
• obtaining a desired target pattern having features to be imaged on a substrate;
• generating an interference map based on said target pattern, said interference map defining areas of constructive interference and areas of destructive interference between at least one of said features to be imaged and a field area adjacent said at least one feature;
• and
• placing assist features in the mask design based on the areas of constructive interference and the areas of destructive interference.