Method and Apparatus for Performing Dark Field Double Dipole Lithography (DDL)

A method of generating complementary masks for use in a dark field double dipole imaging process, said method comprising the steps of:

• identifying a target pattern having a plurality of features, said plurality of features comprising horizontal and vertical features;
• generating a horizontal dark field mask based on said target pattern, said horizontal dark field mask including low contrast features, said generation of said horizontal dark field mask comprising the steps of:
• optimizing the bias of said low contrast features contained in said horizontal dark field mask;
• and
• applying assist features to said horizontal dark field mask;
• generating a vertical dark field mask based on said target pattern, said vertical dark field mask containing low contrast features, said generation of said vertical dark field mask comprising the steps of:
• optimizing the bias of low contrast features contained in said vertical dark field mask;
• and
• applying assist features to said vertical dark field mask;
• and
• decomposing the target pattern into the horizontal dark field mask and the vertical dark field mask, the decomposing comprising:
• performing model-based optimization of both masks so as to optimize imaging performance criteria after double exposure of a feature in the target pattern during the dark field double dipole imaging process using both masks and linear polarization.

A method of generating complementary masks for use in a dark field double dipole imaging process, said method comprising the steps of:

• identifying a target pattern having a plurality of features, said plurality of features comprising horizontal and vertical features;
• generating a horizontal dark field mask based on said target pattern, said horizontal dark field mask including low contrast features, said generation of said horizontal dark field mask comprising the steps of:
• optimizing the bias of said low contrast features contained in said horizontal dark field mask;
• and
• applying assist features to said horizontal dark field mask;
• and
• generating a vertical dark field mask based on said target pattern, said vertical dark field mask containing low contrast features, said generation of said vertical dark field mask comprising the steps of:
• optimizing the bias of low contrast features contained in said vertical dark field mask;
• applying assist features to said vertical dark field mask,
• wherein one or both of said steps of optimizing the bias of said low contrast features includes maximizing one or more performance criteria of an imaging process using linear polarization.