Assist features for use in lithographic projection
AssigneeASML Netherlands B.V.
InventorsJohannes Jacobus Matheus Baselmans, Markus Schluter, Donis George Flagello, Robert John Socha
Life of this patent
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Abstract
In a mask pattern for a device such as a DRAM including a nearly regular array of isolated features, assist features are positioned so as to make the array more symmetric. Where the isolated features are positioned at most but not all of the points of a regular unit cell, the assist features may be positioned at the points of the unit cell not occupied by the isolated features. The isolated features may represent contact holes.
Claims62
A mask for use in a lithographic apparatus, the mask comprising a plurality of isolated areas that contrast with a background and represent features to be printed in manufacture of a device, said isolated areas being arranged in an array such that at least part of each isolated area is adjacent to at least part of at least one other isolated area in the array;
- and
- a plurality of non-printing assist features smaller than and distinct from said isolated areas, at least one of said plurality of assist features being positioned so as to make an aerial image of one of said isolated areas more similar to an aerial image of another of said isolated areas,
- wherein an axis of symmetry of said at least one assist feature, an axis of symmetry of the array, and an axis of symmetry of at least one of said isolated areas are substantially coincident.
A method of making a mask for use in a lithographic apparatus, the method comprising:
- defining a plurality of isolated areas that contrast with a background and represent features to be printed in manufacture of a device, said isolated areas being arranged in an array such that at least part of each isolated area is adjacent to at least part of at least one other isolated area in the array;
- and
- defining a plurality of non-printing assist features smaller than and distinct from said isolated areas, at least one of said plurality of assist features being positioned so as to make an aerial image of one of said isolated areas more similar to an aerial image of another of said isolated areas,
- wherein an axis of symmetry of said at least one assist feature, an axis of symmetry of the array, and an axis of symmetry of at least one of said isolated areas are substantially coincident.
A method of manufacturing a device using a lithographic apparatus comprising:
- imaging irradiated portions of a mask onto target portions of a substrate, wherein said mask is provided with a plurality of isolated areas that contrast with a background and represent features to be printed in manufacture of a device, said isolated areas being arranged in an array such that at least part of each isolated area is adjacent to at least part of at least one other isolated area in the array, and a plurality of non-printing assist features smaller than and distinct from said isolated areas, at least one of said plurality of assist features being positioned so as to make an aerial image of one of said isolated areas more similar to an aerial image of another of said isolated areas,
- wherein an axis of symmetry of said at least one assist feature, an axis of symmetry of the array, and an axis of symmetry of at least one of said isolated areas are substantially coincident.
A mask for use in a lithographic apparatus, the mask comprising:
- a plurality of isolated areas that contrast with a background and represent features to be printed on a substrate, said isolated areas being substantially mutually identical and arranged in an array such that at least part of each isolated area is adjacent to at least part of at least one other isolated area in the array;
- and
- a plurality of assist features that are smaller than a resolution limit of said apparatus, at least one of said plurality of assist features being arranged adjacent to a first edge of a first isolated area of the array and to a second edge of another isolated area,
- wherein the shortest distance between the first and second edges is at least twice the shortest distance from (A) the first edge to (B) an edge of the first isolated area opposite the first edge.
A computer program product including machine-readable instructions describing a method of making a mask for use in a lithographic apparatus, said method comprising:
- defining a plurality of isolated areas that contrast with a background and represent features to be printed in manufacture of a device, said isolated areas being arranged in an array such that at least part of each isolated area is adjacent to at least part of at least one other isolated area in the array;
- and
- defining a plurality of non-printing assist features smaller than and distinct from said isolated areas, at least one of said plurality of assist features being positioned so as to make an aerial image of one of said isolated areas more similar to an aerial image of another of said isolated areas,
- wherein an axis of symmetry of said at least one assist feature, an axis of symmetry of the array, and an axis of symmetry of at least one of said isolated areas are substantially coincident.
A mask for use in a lithographic apparatus, the mask comprising an array having a plurality of isolated areas that contrast with a background and represent features to be printed on a substrate, said isolated areas being arranged such that at least part of each isolated area is adjacent to at least part of at least one other isolated area;
- and
- a plurality of non-printing assist features smaller than said isolated areas, at least one of said plurality of non-printing assist features being arranged adjacent to a first edge of a first isolated area of the array and to a second edge of another isolated area,
- wherein the shortest distance between the first and second edges is at least twice the shortest distance from (A) the first edge to (B) an edge of the first isolated area opposite the first edge.
A method of making a mask for use in a lithographic apparatus, the method comprising:
- defining a plurality of isolated areas that contrast with a background and represent features to be printed in manufacture of a device, said isolated areas being arranged in an array such that at least part of each isolated area is adjacent to at least part of at least one other isolated area in the array;
- and
- defining a plurality of non-printing assist features smaller than said isolated areas,
- wherein said defining a plurality of non-printing assist features includes arranging at least one of said plurality of non-printing assist features to be adjacent to a first edge of a first isolated area of the array and to a second edge of another isolated area, and
- wherein the shortest distance between the first and second edges is at least twice the shortest distance from (A) the first edge to (B) an edge of the first isolated area opposite the first edge.
A method of manufacturing a device using a lithographic apparatus, said method comprising:
- imaging irradiated portions of a mask onto target portions of a substrate, wherein said mask is provided with a plurality of isolated areas that contrast with a background and represent features to be printed on a substrate, said isolated areas being arranged such that at least part of each isolated area is adjacent to at least part of at least one other isolated area, and a plurality of non-printing assist features smaller than said isolated areas, at least one of said plurality of assist features being arranged adjacent to a first edge of a first isolated area of the array and to a second edge of another isolated area,
- wherein the shortest distance between the first and second edges is at least twice the shortest distance from (A) the first edge to (B) an edge of the first isolated area opposite the first edge.
Dependencies are inferred from the claim text.