US 7,398,508 B2Granted

Eigen decomposition based OPC model

AssigneeASML Masktooks B.V.

InventorsXuelong Shi, Robert J. Socha, Thomas Laidig, Douglas Van Den Broeke

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Abstract

Model OPC is developed based on eigen decomposition of an aerial image expected to be produced by a mask pattern on a surface of a resist. With the eigen decomposition method the aerial image intensity distribution around a point (x, y) is accurately described in the model. A scalar approach may be used in the eigen decomposition model which treats the light wave through the mask as a scalar quantity. A eigen decomposition alternatively may use a vector approach which utilizes a vector to describe the light wave and the pupil function. A predicted SPIF may be generated from the aerial image which may be used to verify the mask modeling process by comparing the predicted SPIF to an experimentally determined SPIF. The model OPC, once calibrated, may be used to evaluate performance of a mask and refine features of the mask.

Claims22

Dependent claims

A method for modeling a photolithography process comprising the steps of:

receiving parameters indicative of a target pattern and characteristics of a partially coherent imaging system utilized to image said target pattern;
decomposing said partially coherent imaging system into a series of coherent imaging systems, said series of coherent imaging systems being defined utilizing a plurality of eigen functions;
determining an aerial image intensity distribution expected to be produced on a resist by the target pattern using said plurality of eigen functions and a function representing said target pattern;
and
determining an imaging model based on the aerial image,
wherein said imaging model comprises a system pseudo intensity function (SPIF), said method further comprising the steps of:
applying a constant threshold to the SPIF to generate contours;
comparing the generated contours with expected contours;
and
adjusting weights of each term associated with each eigen function and generating a new SPIF if the generated contours are not within a predetermined tolerance of the expected contours.

7 more elements

A computer readable storage device containing instructions, which when executed by a computer, enables the computer to perform a method for modeling a photolithography process comprising the steps of:

receiving parameters indicative of a target pattern and characteristics of a partially coherent imaging system utilized to image said target pattern;
decomposing said partially coherent imaging system into a series of coherent imaging systems, said series of coherent imaging systems being defined utilizing a plurality of eigen functions;
determining an aerial image intensity distribution expected to be produced on a resist by the target pattern using said plurality of eigen functions and a function representing said target pattern;
and
determining an imaging model based on the aerial image,
wherein said imaging model comprises a system pseudo intensity function (SPIF), said computer readable medium further containing instructions to enable the computer to perform the steps of:
applying a constant threshold to the SPIF to generate contours;
comparing the generated contours with expected contours;
and
adjusting weights of each term associated with each eigen function and generating a new SPIF if the generated contours are not within a predetermined tolerance of the expected contours.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/981,750Filed 5 Nov 2004 · us provisional application
Priority: 5 Nov 2003
Published: US 2005/0149902 A17 Jul 2005
Granted: 8 Jul 2008
Term ends: Not estimatedThe source records don’t support an estimate.

Classification3 codes

G03F 1/36
Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles…
G03F 7/705
Information management, e.g. software; Active and passive control, e.g. details of controlling exposure processes or exposure tool monitoring…:…
G03F
Photomechanical production of textured or patterned surfaces