Optimization of assist features and source
AssigneeASML Netherlands B.V.
InventorsDuan-Fu Stephen Hsu, Feng-Liang Liu
Life of this patent
Estimating the term…
Abstract
Methods of reducing a pattern displacement error, contrast loss, best focus shift, and/or tilt of a Bossung curve of a portion of a design layout used in a lithographic process for imaging that portion onto a substrate using a lithographic apparatus. The methods include adjusting an illumination source of the lithographic apparatus, placing one or more assist features onto, or adjusting a position and/or shape of one or more existing assist features in, the portion. Adjusting the illumination source and/or the one or more assist features may be by an optimization algorithm.
Claims20
A method to improve a lithographic process for imaging a portion of a design layout onto a substrate using a lithographic apparatus and a physical patterning device, the method comprising:
- reducing a pattern displacement error, contrast loss, best focus shift, tilt of a Bossung curve of the portion, or a combination selected therefrom, or improving exposure latitude, or enlarging depth of focus, by adjusting a characteristic of an illumination in the lithographic apparatus;
- calculating, by a hardware computer system, a continuous transmission map of the portion;
- identifying numbers, positions, shapes or a combination selected therefrom, of assist features from the continuous transmission map, wherein at least two of the assist features are located in an asymmetric position with respect to a same feature of the design layout;
- and
- placing the one or more assist features onto a pattern layout for the patterning device,
- where the pattern layout is configured for implementation within the physical patterning device, and
- where the lithographic process comprises a step of physically imaging the portion of the design layout onto the substrate using the physical patterning device implementing the pattern layout.
A method comprising:
- reducing a pattern displacement error, contrast loss, best focus shift, tilt of a Bossung curve, or a combination selected therefrom, of a portion of a design layout for imaging onto a substrate using a physical patterning device and a lithographic apparatus, or improving exposure latitude, or enlarging depth of focus, by adjusting a characteristic of a data structure representing an illumination in the lithographic apparatus;
- calculating, by a hardware computer system, a continuous transmission map of the portion of the design layout;
- and
- generating a data structure representing a pattern layout for the patterning device, the data structure representing assist features, wherein numbers, positions, shapes or a combination selected therefrom, of the assist features are identified from the continuous transmission map and at least two of the assist features are located in an asymmetric position with respect to a same feature of the design layout,
- where the pattern layout is configured for implementation within the physical patterning device, and
- where the lithographic process comprises a step of physically imaging the portion of the design layout onto the substrate using the physical patterning device implementing the pattern layout.
A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions, when executed by a computer system, are configured to cause the computer system to at least:
- reduce a pattern displacement error, contrast loss, best focus shift, tilt of a Bossung curve, or a combination selected therefrom, of a portion of a design layout for imaging onto a substrate using a physical patterning device and a lithographic apparatus, or improve exposure latitude, or enlarge depth of focus, by adjusting a characteristic of a data structure representing an illumination in the lithographic apparatus;
- calculate a continuous transmission map of the portion of the design layout;
- and
- generate a data structure representing a pattern layout for the patterning device, the data structure representing assist features, wherein numbers, positions, shapes or a combination selected therefrom, of the assist features are identified from the continuous transmission map and at least two of the assist features are located in an asymmetric position with respect to a same feature of the design layout,
- where the pattern layout is configured for implementation within the physical patterning device, and
- where the lithographic process comprises a step of physically imaging the portion of the design layout onto the substrate using the physical patterning device implementing the pattern layout.
A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions, when executed by a computer system, are configured to cause the computer system to at least:
- reduce a pattern displacement error, contrast loss, best focus shift, tilt of a Bossung curve, or a combination selected therefrom, of a portion of a design layout for imaging onto a substrate using a physical patterning device and the lithographic apparatus, or improve exposure latitude, or enlarge depth of focus, by adjusting a characteristic of a data structure representing an illumination in the lithographic apparatus such that the illumination has an asymmetric shape;
- and
- generate a data structure representing a pattern layout for the patterning device, the data structure representing assist features, wherein numbers, positions, shapes or a combination selected therefrom, of the assist features are identified based on the illumination and at least two of the assist features are located in an asymmetric position with respect to a same feature of the design layout,
- where the pattern layout is configured for implementation within the physical patterning device, and
- where the lithographic process comprises a step of physically imaging the portion of the design layout onto the substrate using the physical patterning device implementing the pattern layout.
Dependencies are inferred from the claim text.