Incrementally resolved phase-shift conflicts in layouts for phase-shifted features

A method for providing a layout for shifters, the method comprising the steps of:

• identifying a current set of critical features consisting of all critical features in a current hierarchical unit of a physical design layout;
• if the unit is a first unit in its branch, placing shifters for the current set of critical features;
• checking the shifters for the current set of critical features for conformance with design rules regarding shifter positions;
• deriving shifters for the current set of critical features in response to said checking;
• assigning relative phases to the shifters for the current set of critical features;
• determining whether there is a phase-shift conflict within the unit that cannot be resolved;
• if there is a phase-shift conflict within the unit that cannot be resolved, then notifying a physical design layout process to adjust the physical design layout;
• and
• if there is not a phase-shift conflict within the unit that cannot be resolved, then
• if the unit is a hierarchical root unit, associating absolute phases with the relative phases, and
• if the unit is not the hierarchical root unit, making a next hierarchical unit-the current hierarchical unit, and returning to the identifying step.

A computer system for producing a physical design layout with shifters, the system comprising:

• a memory medium;
• and
• one or more processors configured for:
• identifying a current set of critical features consisting of all critical features in a current hierarchical unit of a physical design layout;
• if the unit is a first unit in its branch, placing shifters for the current set of critical features;
• checking the shifters for the current set of critical features for conformance with design rules regarding shifter positions;
• deriving shifters for the current set of critical features in response to said checking;
• assigning relative phases to the shifters for the current set of critical features;
• determining whether there is a phase-shift conflict within the unit that cannot be resolved;
• if there is a phase-shift conflict within the unit that cannot be resolved, then notifying a physical design layout process to adjust the physical design layout;
• and
• if there is not a phase-shift conflict within the unit that cannot be resolved, then
• if the unit is a hierarchical root unit, associating absolute phases with the relative phases, and
• if the unit is not the hierarchical root unit, making a next hierarchical unit the current hierarchical unit, and returning to the identifying step.

A system for producing a layout with shifters, the system comprising:

• means for identifying a current set of critical features consisting of all critical features in a current hierarchical unit of a physical design layout;
• means for placing shifters for the current set of critical features if the unit is a the first unit in its branch;
• means for checking the shifters for the current set of critical features for conformance with design rules regarding shifter positions;
• means for deriving shifters for the current set of critical features in response to said checking;
• means for assigning relative phases to the shifters for the current set of critical features;
• means for determining whether there is a phase-shift conflict within the unit that cannot be resolved;
• means for notifying a physical design layout process to adjust the physical design layout if there is a phase-shift conflict within the unit that cannot be resolved;
• means for associating absolute phases with the relative phases if there is not a phase-shift conflict within the unit that cannot be resolved and the unit is a hierarchical root unit;
• and
• means for making a next hierarchical unit the current hierarchical unit and returning to the identifying step if there is not a phase-shift conflict within the unit that cannot be resolved and the unit is not the hierarchical root unit.

A computer readable medium for aiding the formation of a fabrication layout for a physical design layout with critical features requiring phase shifting, the computer readable medium carrying instructions to cause one or more processors to perform the steps of:

• identifying a current set of critical features consisting of all critical features in a current hierarchical unit of a physical design layout;
• if the unit is a first unit in its branch, placing shifters for the current set of critical features;
• checking the shifters for the current set of critical features for conformance with design rules regarding shifter positions;
• deriving shifters for the current set of critical features in response to said checking;
• assigning relative phases to the shifters for the current set of critical features;
• determining whether there is a phase-shift conflict within the unit that cannot be resolved;
• if there is a phase-shift conflict within the unit that cannot be resolved, then notifying a physical design layout process to adjust the physical design layout;
• and
• if there is not a phase-shift conflict within the unit that cannot be resolved, then
• if the unit is a hierarchical root unit, associating absolute phases with the relative phases, and
• if the unit is not the hierarchical root unit,
• making a next hierarchical unit the current hierarchical unit, and returning to the identifying step.