Lens heating aware source mask optimization for advanced lithography

Patent metadata

Field	Value
Publication number	US-9940427-B2
Application number	US-201313753401-A
Country	US
Kind code	B2
Filing date	Jan 29, 2013
Priority date	Feb 9, 2012
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

A computer-implemented method for improving a lithographic process for imaging a portion of a design layout onto a substrate using a lithographic projection apparatus comprising an illumination source and projection optics, the method including computing a multi-variable cost function of a plurality of design variables that are characteristics of the lithographic process, at least some of the design variables being characteristics of the illumination source and the design layout, the computing of the multi-variable cost function accounting for lens heating effects; and reconfiguring the characteristics of the lithographic process by adjusting the design variables until a predefined termination condition is satisfied.

First claim

What is claimed is:

1. A method for improving a lithographic process for imaging at least a portion of a design layout onto a substrate using a lithographic projection apparatus comprising an illumination system and projection optics, the method comprising:
computing, by a hardware computer system, a multi-variable cost function of a plurality of design variables that are characteristics of the lithographic process, at least some of the design variables being characteristics of illumination to be provided by the illumination system and of the design layout, the computing of the multi-variable cost function accounting for an effect on an optical characteristic of the projection optics induced by imaging the portion of the design layout with the illumination through the projection optics; and
reconfiguring the characteristics of the lithographic process by adjusting the design variables of the cost function until a defined termination condition of computing the cost function is satisfied,
wherein the effect is determined using at least some of the design variables that are characteristics of the design layout and of the illumination.

2. The method of claim 1 , wherein the effect comprises a heating effect.

3. The method of claim 1 , wherein computing the multi-variable cost function comprises using a projection optics model that is a function of the effect.

4. The method of claim 1 , wherein the reconfiguring comprises redetermining the effect using at least some of the design variables that are characteristics of the design layout and/or of the illumination and that are adjusted.

5. The method of claim 1 , wherein the reconfiguring comprises computing the multi-variable cost function using a projection optics model that is a function of the effect.

6. The method of claim 1 , wherein the design variables comprise an adjustable optical characteristic of the projection optics.

7. The method of claim 6 , wherein the adjustable optical characteristic comprises a refractive index of at least a portion of the projection optics, or a temperature of at least a portion of the projection optics, or a Zernike coefficient of the projection optics.

8. The method of claim 6 , wherein the adjustable optical characteristic is adjustable by a heater configured to heat an optical element of the projection optics.

9. The method of claim 1 , wherein the design layout comprises at least one assist feature and wherein the at least one assist feature comprises a SRAF (Sub Resolution Assist Feature) and/or a PRAF (Printable Resolution Assist Feature).

10. The method of claim 1 , further comprising determining the effect using at least some of the design variables that are characteristics of the illumination and a simplified reticle.

11. The method of claim 10 , wherein the simplified reticle is selected from: an estimated reticle transmission, a measured average transmission of a physical mask, a clip from a reticle, or a plurality of discrete portions of a reticle.

12. A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions configured to cause a computer to:
compute a multi-variable cost function of a plurality of design variables that are characteristics of a lithographic process for imaging a portion of a design layout onto a substrate using a lithographic projection apparatus that comprises an illumination system and projection optics, at least some of the design variables being characteristics of illumination to be provided by the illumination system and of the design layout, the computing of the multi-variable cost function accounting for an effect on an optical characteristic of the projection optics induced by imaging the portion of the design layout with the illumination through the projection optics; and
reconfigure the characteristics of the lithographic process by adjusting the design variables of the cost function until a defined termination condition of computing the cost function is satisfied,
wherein the effect is determined using at least some of the design variables that are characteristics of the design layout and of the illumination.

13. The computer program product of claim 12 , wherein the effect comprises a heating effect.

14. The computer program product of claim 12 , wherein the instructions configured to compute the multi-variable cost function are configured to use a projection optics model that is a function of the effect.

15. The computer program product of claim 12 , wherein the instructions are further configured to determine the effect using at least some of the design variables that are characteristics of the illumination and a simplified reticle.

16. The computer program product of claim 15 , wherein the simplified reticle is selected from: an estimated reticle transmission, a measured average transmission of a physical mask, a clip from a reticle, or a plurality of discrete portions of a reticle.

17. A computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions configured to cause a computer to:
compute a multi-variable cost function of a plurality of design variables that are characteristics of a lithographic process for imaging a portion of a design layout onto a substrate using a lithographic projection apparatus that comprises an illumination system and projection optics, at least some of the design variables being characteristics of illumination to be provided by the illumination system and of the design layout, the computing of the multi-variable cost function accounting for an effect on an optical characteristic of the projection optics induced by imaging the portion of the design layout with the illumination through the projection optics; and
reconfigure the characteristics of the lithographic process by adjusting the design variables of the cost function until a defined termination condition of computing the cost function is satisfied,
wherein computation of the multi-variable cost function comprises use of a projection optics model that is a function of the effect.

18. The computer program product of claim 17 , wherein the effect comprises a heating effect.

19. The computer program product of claim 17 , wherein the instructions are further configured to determine the effect using at least some of the design variables that are characteristics of the illumination and a simplified reticle.

20. The computer program product of claim 19 , wherein the simplified reticle is selected from: an estimated reticle transmission, a measured average transmission of a physical mask, a clip from a reticle, or a plurality of discrete portions of a reticle.

Assignees

• Crouse Michael Matthew M
• Van Dommelen Youri Johannes Laurentius Maria
• Liu Peng
• Liu Hua Yu
• Jiang Aiqin
• Huang Wenjin
• Asml Netherlands Bv

Inventors

• Crouse Michael Matthew M
• Van Dommelen Youri Johannes Laurentius Maria
• Liu Peng
• Liu Hua-Yu
• Jiang Aiqin
• Huang Wenjin

Classifications

• G03F7/70433

  Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors · CPC title

• G03F7/705

  Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions · CPC title

• G03F7/70891

  Temperature · CPC title

• G06F30/398 Primary

  Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] (optical proximity correction [OPC] design processes G03F1/36) · CPC title

• G03F7/70125 Primary

  Use of illumination settings tailored to particular mask patterns (details of setting means G03F7/70091) · CPC title