Method for decomposition of a customized DOE for use with a single exposure into a set of multiple exposures using standard DOEs with optimized exposure settings

• US 7,804,646 B2
• Filed: 01/31/2007
• Issued: 09/28/2010
• Est. Priority Date: 01/31/2006
• Status: Expired due to Fees

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Masktools B.V. (ASML Holding NV)
• Inventors: Chen, Ting, Chen, Jang Fung
• Primary Examiner(s): Pritchett; Joshua L
• Application Number:
  US11/700,231
• Publication Number:
  US 20070195394A1
• Time in Patent Office: 1,336 Days
• Field of Search: 359/558, 355/52, 355/53, 355/55, 355/67, 369/285
• US Class Current: 359/558
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 27/0012 Optical design, e.g. procedures, algorithms, optimisation routines
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
• CPC Class Codes: G03F 7/70108 Off-axis setting using a light-guiding element, e.g. diffractive optical elements [DOEs] or light guides
• CPC Class Codes: G03F 7/70466 Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature stitching G03F7/70475
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions

Abstract

A method of determining diffractive optical elements to be utilized in an imaging process. The method includes the steps of defining a customized diffractive optical element which is based on a target pattern to be printed during the imaging process; decomposing the customized diffractive optical element into one or more standard diffractive optical elements; and defining an exposure dose to be assigned to each of the one or more standard diffractive optical elements.

Claims

1. A method of determining diffractive optical elements to be utilized in an imaging process, said method comprising the steps of:

defining a customized diffractive optical element which is based on a target pattern to be printed during said imaging process;

decomposing said customized diffractive optical element into one or more standard diffractive optical elements; and

defining an exposure dose to be assigned to each of said one or more standard diffractive optical elements,

wherein the one or more standard diffractive optical elements are adapted to adjust characteristics of radiation that projects from an illumination source in the imaging process, and wherein the radiation, after it has been projected from the illumination source, illuminates a mask having features corresponding to the target pattern during the imaging process, so as to print the target pattern on a wafer.

2. The method of claim 1, wherein said step of decomposing said customized diffractive optical element into one or more standard diffractive optical elements, includes:

identifying components forming said customized diffractive optical element;

assigning a standard diffractive optical element to each of said components of said customized diffractive optical element; and

adjusting variable settings associated with each said standard diffractive optical element so as so minimize the differences between the imaging performance of each standard diffractive optical element and the corresponding component of the customized diffractive optical element.

3. The method of claim 2, wherein said variable settings include the size of the illumination openings on each said standard diffractive optical element.

4. The method of claim 2, wherein said variable settings include an exposure dose setting;

a numerical aperture setting; and

a defocus setting.

5. The method of claim 2, further assigning an exposure dose to each of said standard diffractive optical elements, said exposure dose being a weighted value based on an exposure dose setting assigned to said customized diffractive optical element.

6. The method of claim 1, wherein said standard diffractive optical elements include conventional illumination, annular illumination, X-dipole illumination, Y-dipole illumination, Quasar illumination, Cquad illumination and hexapole illumination.

7. A method according to claim 1, wherein the characteristics include one or more of illumination shape and illumination intensity.

8. A method of imaging a mask having a target pattern, said method comprising the steps of:

defining a set of process parameters to be utilized to image said mask;

defining a customized diffractive optical element which is based on said target pattern and said set of process parameters;

decomposing said customized diffractive optical element into one or more standard diffractive optical elements;

defining an exposure dose to be assigned to each of said one or more standard diffractive optical elements, and

utilizing said one or more standard diffractive optical elements to adjust characteristics of radiation projected from an illumination source when imaging said mask, wherein the radiation illuminates the mask after it has been projected from the illumination source.

9. The method of claim 8, wherein said step of decomposing said customized diffractive optical element into one or more standard diffractive optical elements, includes:

identifying components forming said customized diffractive optical element;

assigning a standard diffractive optical element to each of said components of said customized diffractive optical element; and

adjusting variable settings associated with each said standard diffractive optical element so as so minimize the differences between the imaging performance of each standard diffractive optical element and the corresponding component of the customized diffractive optical element.

10. The method of claim 9, wherein said variable settings include the size of the illumination openings on each said standard diffractive optical element.

11. The method of claim 9, wherein said variable settings include an exposure dose setting;

a numerical aperture setting; and

a defocus setting.

12. The method of claim 9, further assigning an exposure dose to each of said standard diffractive optical elements, said exposure dose being a weighted value based on an exposure dose setting assigned to said customized diffractive optical element.

13. The method of claim 8, wherein said standard diffractive optical elements include conventional illumination, annular illumination, X-dipole illumination, Y-dipole illumination, Quasar illumination, Cquad illumination and hexapole illumination.

14. A method according to claim 8, wherein the characteristics include one or more of illumination shape and illumination intensity.