US 6,609,245 B2Granted

Priority coloring for VLSI designs

AssigneeInternational Business Machines Corporation

InventorsLars W. Liebmann, Carlos A. Fonseca, Ioana Graur, Young O. Kim

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Abstract

A method and computer program product is described for optimizing the design of a circuit layout that assigns binary properties to the design elements according to a hierarchy of rules. For example, the design of an alternating phase shifted mask (altPSM) is optimized first according to rules that assign phase shapes that maximize image quality for critical circuit elements, and then further optimized to minimize mask manufacturability problems without significantly increasing the complexity of the design process flow. Further optimization of the design according to additional rules can be performed in a sequentially decreasing priority order. As the priority of rules decrease, some violation of lower priority rules may be acceptable, as long as higher priority rules are not violated.

Claims18

Dependent claims

A method for designing an alternating phase shifting mask (altPSM), the mask including a substrate, the method comprising:

providing a circuit layout;
providing a cutoff layout dimension;
identifying a plurality of critical elements of said circuit layout wherein each of said plurality of critical elements has a sub-cutoff dimension less than said cutoff dimension;
generating a first phase shape and a second phase shape disposed on opposing sides of each of said sub-cutoff dimensions;
providing a first function for defining a phase shape intrusion pair, so that at least said first phase shape and said second phase shape form an intrusion pair;
forming a plurality of nets wherein each of said nets comprises at least one phase shape intrusion pair formed in accordance with said first function;
coloring phase shapes within each of said nets so that said first phase shape and said second phase shape are assigned opposite phase colors;
providing a second function for defining a net intrusion pair in accordance with a manufacturability constraint;
selecting a first net and a second net adjacent to said first net, said first net having a first net edge comprising an outside edge of a first edge phase shape included in said first net, said second net having a second net edge comprising an outside edge of a second edge phase shape included in said second net, wherein said first edge phase shape and said second edge phase shape are assigned a same phase color requiring etching of the substrate and wherein said first net edge and second net edge are adjacent to each other and separated by a background space;
forming a third net comprising said first net and said second net in accordance with said second function;
and
recoloring phase shapes within said third net so that each of said first phase shapes and said second phase shapes are assigned opposite phase colors across each of said critical dimensions and so that said first edge phase shape and said second edge phase shape are assigned opposite phase colors across said background space.

9 more elements

A computer program product comprising a computer readable storage medium having stored therein instructions executable by the computer for performing a method for designing an alternating phase shifting mask (altPSM), the mask including a substrate, the method comprising:

providing a circuit layout;
providing a cutoff layout dimension;
identifying a plurality of critical elements of said circuit layout wherein each of said plurality of critical elements has a sub-cutoff dimension less than said cutoff dimension;
generating a first phase shape and a second phase shape disposed on opposing sides of each of said sub-cutoff dimensions;
providing a first function for defining a phase shape intrusion pair, so that at least said first phase shape and said second phase shape form an intrusion pair;
forming a plurality of nets wherein each of said nets comprises at least one phase shape intrusion pair formed in accordance with said first function;
coloring phase shapes within each of said nets so that said first phase shape and said second phase shape are assigned opposite phase colors;
providing a second function for defining a net intrusion pair in accordance with a manufacturability constraint;
selecting a first net and a second net adjacent to said first net, said first net having a first net edge comprising an outside edge of a first edge phase shape included in said first net, said second net having a second net edge comprising an outside edge of a second edge phase shape included in said second net, wherein said first edge phase shape and said second edge phase shape are assigned a same phase color requiring etching of the substrate and wherein said first net edge and second net edge are adjacent to each other and separated by a background space;
forming a third net comprising said first net and said second net in accordance with said second function;
and
recoloring phase shapes within said third net so that each of said first phase shapes and said second phase shapes are assigned opposite phase colors across each of said critical dimensions and so that said first edge phase shape and said second edge phase shape are assigned opposite phase colors across said background space.

9 more elements

Dependencies are inferred from the claim text.