Lithographic apparatus and method for optimizing an illumination source using isofocal compensation

Claim 3

A method according to claim 1 , wherein calculating the metric comprises: applying a defocus; calculating separate defocus responses for individual source points at the defocus, each of the defocus responses representing a result of a single or series of simulations using the simulation model; and comparing the separate responses with the separate defocus responses for individual source points.

Claim 4

A method according to claim 2 , wherein the comparing comprises determining separate metric responses for individual source points.

Claim 5

A method according to claim 3 , wherein the separate metric responses correspond either to an augmentation of the value of the defocus response or a diminution of the value of the defocus response.

Claim 6

A method according to claim 3 , wherein the determining comprises subtracting the separate defocus responses from the separate responses for individual source points.

Claim 7

A method according to claim 3 , wherein the adjusting comprises mapping the metric responses as a function of individual source point positions.

Claim 8

A method according to claim 4 , wherein the adjusting comprises selecting an illumination arrangement capturing source points having opposite metric response behaviors.

Claim 9

A method according to claim 1 , wherein the defocus is within a range from 0.02 to 0.4 μm.

Claim 10

A method according to claim 1 , wherein selecting a simulation model comprises selecting one of a full resist model, an aerial image model, a lumped parameter model and a variable threshold resist model.

Claim 11

A method according to claim 9 , wherein the resist model is a calibrated model capable of adequately predicting experimental results.

Claim 12

A method according to claim 9 , wherein the resist model includes defining a resist model taking into account at least one of vector effects, non-zero diffusion of active species, and finite dissolution contrast.

Claim 13

A method according to claim 1 , wherein the separate responses comprise one of a critical dimension of the pattern and an intensity threshold.

Claim 14

A method according to claim 1 , wherein the adjusting comprises selecting an illumination arrangement so that the variation of the separate responses is substantially equal to zero through defocus.

Claim 15

A method according to claim 1 , further comprising calculating other separate responses for individual source points, each of the other responses representing a result of a single or series of simulation using the simulation model.

Claim 16

A method according to claim 14 , wherein the adjusting comprises adjusting an illumination arrangement based on analysis of the other separate responses.

Claim 17

A method according to claim 14 , wherein the other responses comprise one of exposure latitude, depth of focus, E1:1, dense to isolated features bias, arbitrary feature biases, sidelobe printing, film loss, sidewall angle, mask error enhancement factor, linear resolution and absolute resolution.

Claim 18

A method according to claim 14 , further comprising mapping the other separate responses as a function of individual source point positions.

Claim 19

A method according to claim 1 , further comprising mapping the variation of the separate responses as a function of individual source points positions.

Claim 20

A method according to claim 1 , wherein a spacing of the source point in the grid is within a range from 0.01 to 0.2.

Claim 21

A method according to claim 1 , wherein adjusting the illumination arrangement includes adjusting illumination arrangement by varying a position of an axicon/zoom module relative to a pyramidal prism, a position of a diffractive optical element, a position of an aperture blade, or by adjusting a programmable mirror array.

Claim 22

A method according to claim 1 , wherein adjusting the illumination arrangement includes selecting a multipole illuminator arrangement.

Claim 23

A device manufacturing method comprising: providing a mask; and projecting a patterned beam of radiation onto a target portion of a layer of radiation-sensitive material on a substrate, wherein, prior to impinging the mask, a cross-sectional intensity distribution in the projection beam is optimized using a method according to claim 1 .

Claim 24

A method according to claim 4 , wherein the adjusting comprises weighing the individual source points.

Claim 25

A lithographic projection apparatus comprising: an illumination system to provide a projection beam of radiation a support structure to support patterning structure which can be used to pattern the projection beam according to a desired pattern; a substrate table to hold a substrate; a projection system to project the patterned beam onto a target portion of the substrate; a processor to define a lithographic pattern to be printed on the substrate, to select a grid of source points in a pupil plane of the illumination system, to calculate separate responses for individual source points, each of the responses representing a result of a single or series of simulations using a simulation model, to calculate a metric representing variation of the separate responses for individual source points with defocus; and to calculate an optimized illumination arrangement based on analysis of the metric; and a selectably variable beam controller that is adapted to modify a cross-sectional intensity distribution in the projection beam exiting the illumination system in accordance with the optimized illumination arrangement calculated by the processor.

Claim 26

A lithographic projection apparatus comprising: an illumination system to provide a projection beam of radiation a support structure to support patterning structure which can be used to pattern the projection beam according to a desired pattern; a substrate table to hold a substrate; a projection system to project the patterned beam onto a target portion of the substrate; a processor to define a lithographic pattern to be printed on the substrate, to select a grid of source points in a pupil plane of the illumination system, to calculate separate responses for individual source points, each of the responses representing a result of a single or series of simulations using a simulation model, to calculate a metric representing variation of the separate responses for individual source points with defocus; and to calculate an optimized illumination arrangement based on analysis of the metric; and a selectably variable beam controller that is adapted to modify a cross-sectional intensity distribution in the projection beam exiting the illumination system in accordance with the optimized illumination arrangement calculated by the processor.

Claim 27

A machine readable medium encoded with machine executable instructions for optimizing an illumination condition of an illuminator using isofocal compensation according to a method comprising: defining a lithographic pattern to be printed on a substrate; selecting a simulation model; selecting a grid of source points in a pupil plane of the illuminator; calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the simulation model; calculating a metric representing variation of the separate responses for individual source points with defocus; and adjusting an illumination arrangement based on analysis of the metric.

Claim 28

A machine readable medium encoded with machine executable instructions for optimizing an illumination condition of an illuminator using isofocal compensation according to a method comprising: defining a lithographic pattern to be printed on a substrate; selecting a simulation model; selecting a grid of source points in a pupil plane of the illuminator; calculating separate responses for individual source points, each of the responses representing a result of a single or series of simulations using the simulation model; calculating a metric representing variation of the separate responses for individual source points with defocus; and adjusting an illumination arrangement based on analysis of the metric.