Back to results
US 6,646,729 B2Granted
Method of measuring aberration in an optical imaging system
AssigneeASML Netherlands B.V.
InventorsHans van der Laan, Marco H Moers
Life of this patent
Estimating the term…
Abstract
A method of determining aberration of an optical imaging system comprises measuring at least one parameter, such as position of best-focus and/or lateral position, of an image formed by the imaging system. This is repeated for a plurality of different illumination settings of the imaging system, and from these measurements at least one coefficient, representative of aberration of said imaging system, is calculated.
Claims17
A method of determining aberration of an optical imaging system, comprising:
- a radiation system constructed and arranged to supply a projection beam of radiation;
- a support structure constructed and arranged to support a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern;
- a substrate table constructed and arranged to hold a substrate;
- and
- a projection system constructed and arranged to project the patterned beam onto a target portion of the substrate;
- the method comprising:
- patterning the projection beam with said patterning device;
- measuring at least one parameter of an image formed by the projection system, for a plurality of different illumination settings of said radiation system and/or for a plurality of different numerical aperture settings of said projection system;
- and
- calculating at least one coefficient, representative of aberration of said imaging system, on the basis of said at least one parameter measured at said plurality of settings.
7 more elements
A method of determining aberration of an optical imaging system, comprising:
- a radiation system constructed and arranged to supply a projection beam of radiation;
- a support structure constructed and arranged to support a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern;
- a substrate table constructed and arranged to hold a substrate;
- and
- a projection system constructed and arranged to project the patterned beam onto a target portion of the substrate;
- the method comprising:
- patterning the projection beam with said patterning device;
- measuring at least one parameter of an image formed by the projection system, for a plurality of different settings of said radiation system and/or said projection system;
- and
- calculating at least one coefficient, representative of aberration of said imaging system, on the basis of said at least one parameter measured at said plurality of settings,
- wherein said plurality of different illumination settings of said radiation system and/or of different numerical aperture settings of said projection system are selected such that the variation in said at least one measured parameter resulting from aberration represented by one or more of said coefficients is substantially zero, while the variation in said at least one parameter as a function of a desired coefficient is non-zero.
8 more elements
A method of determining aberration of an optical imaging system, comprising:
- a radiation system constructed and arranged to supply a projection beam of radiation;
- a support structure constructed and arranged to support a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern;
- a substrate table constructed and arranged to hold a substrate;
- and
- a projection system constructed and arranged to project the patterned beam onto a target portion of the substrate;
- the method comprising:
- patterning the projection beam with said patterning device;
- measuring at least one parameter of an image formed by the projection system, for a plurality of different settings of said radiation system and/or said projection system;
- calculating at least one coefficient, representative of aberration of said imaging system, on the basis of said at least one parameter measured at said plurality of settings;
- and
- calculating a theoretical variation, for each of said plurality of different illumination settings, of said at least one measured parameter as a function of a small change in said at least one coefficient.
8 more elements
A method of determining aberration of an optical imaging system, comprising:
- a radiation system constructed and arranged to supply a projection beam of radiation;
- a support structure constructed and arranged to support a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern;
- a substrate table constructed and arranged to hold a substrate;
- and
- a projection system constructed and arranged to project the patterned beam onto a target portion of the substrate;
- the method comprising:
- patterning the projection beam with said patterning device;
- measuring at least one parameter of an image formed by the projection system, for a plurality of different settings of said radiation system and/or said projection system;
- and
- calculating at least one coefficient, representative of aberration of said imaging system, on the basis of said at least one parameter measured at said plurality of settings,
- wherein said at least one coefficient is calculated by multiple regression or a least-square fit of a set of simultaneous equations.
8 more elements
A method of determining aberration of an optical imaging system, comprising:
- a radiation system constructed and arranged to supply a projection beam of radiation;
- a support structure constructed and arranged to support a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern;
- a substrate table constructed and arranged to hold a substrate;
- and
- a projection system constructed and arranged to project the patterned beam onto a target portion of the substrate;
- the method comprising:
- patterning the projection beam with said patterning device;
- measuring at least one parameter of an image formed by the projection system, for a plurality of different settings of said radiation system and/or said projection system;
- and
- calculating at least one coefficient, representative of aberration of said imaging system, on the basis of said at least one parameter measured at said plurality of settings,
- wherein said at least one coefficient is a Zernike coefficient.
8 more elements
A lithographic projection apparatus for projecting a patterned beam of radiation onto a substrate provided with a radiation-sensitive layer, the apparatus comprising:
- a radiation system constructed and arranged to provide a projection beam of radiation;
- a support structure constructed and arranged to support a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern;
- a substrate table constructed and arranged to hold a substrate;
- a projection system constructed and arranged to project the patterned beam onto a target portion of the substrate;
- an illumination setter constructed and arranged to provide a plurality of different illumination settings of said radiation system and/or a plurality of different numerical aperture settings of said projection system, comprising:
- a measuring device constructed and arranged to measure at least one parameter of a projected image formed by the projection system;
- a controller constructed and arranged to select a plurality of different illumination settings and/or a plurality of different numerical aperture settings at which said measuring device takes measurements;
- and
- a calculator constructed and arranged to calculate at least one coefficient, representative of aberration of said projection and/or radiation system, on a basis of said at least one parameter measured by said measuring device.
6 more elements
A method of manufacturing a device using a lithographic projection apparatus, comprising:
- (a) providing a substrate that is at least partially covered by a layer of radiation-sensitive material;
- (b) providing a projection beam of radiation using a radiation system;
- (c) using a patterning device to endow the projection beam with a pattern in its cross-section;
- (d) using a projection system to project the patterned beam of radiation onto a target portion of the layer of radiation-sensitive material;
- measuring, prior to (d), at least one parameter of an image formed by the projection system, for a plurality of different illumination settings of said radiation system and/or for a plurality of different numerical aperture settings of said projection system;
- calculating at least one coefficient, representative of aberration of said projection and/or radiation system, on a basis of said at least one parameter measured at said plurality of different illumination settings of said radiation system and/or said plurality of different numerical aperture settings of said projection system;
- correcting for said aberration on the basis of said at least one calculated coefficient, to reduce aberration of an image projected by said projection system.
4 more elements
Dependencies are inferred from the claim text.