Optimized correction of wafer thermal deformations in a lithographic process

• US 7,250,237 B2
• Filed: 12/23/2003
• Issued: 07/31/2007
• Est. Priority Date: 12/23/2003
• Status: Expired due to Fees

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Ottens, Joost Jeroen, Venema, Willem Jurrianus, Van Der Schoot, Harmen Klaas, Menchtchikov, Boris, Maas, Wouterus Johannes Petrus Maria, Starreveld, Jeroen Pieter
• Primary Examiner(s): Young; Christopher G.
• Application Number:
  US10/743,272
• Publication Number:
  US 20050136346A1
• Time in Patent Office: 1,316 Days
• Field of Search: 430/22, 430/30, 430/311
• US Class Current: 430/30
• CPC Class Codes: G03F 7/70616 Monitoring the printed patterns
• CPC Class Codes: G03F 7/70783 Handling stress or warp of chucks, masks or workpieces, e.g. to compensate for imaging errors or considerations related to warpage of masks or workpieces due to their own weight
• CPC Class Codes: G03F 7/70875 Temperature, e.g. temperature control of masks or workpieces via control of stage temperature

Abstract

A method and apparatus of correcting thermally-induced field deformations of a lithographically exposed substrate, is presented herein. In one embodiment, the method includes exposing a pattern onto a plurality of fields of a substrate in accordance with pre-specified exposure information and measuring attributes of the fields to assess deformation of the fields induced by thermal effects of the exposing process. The method further includes determining corrective information based on the measured attributes, and adjusting the pre-specified exposure information, based on the corrective information, to compensate for the thermally-induced field deformations.

Other embodiments include the use of predictive models to predict thermally-induced effects on the fields and thermographic imaging to determine temperature variations across a substrate.

Claims

1. A method of correcting thermally-induced field deformations of a lithographically exposed substrate, comprising:

exposing a pattern onto a plurality of fields of a substrate in accordance with pre-specified exposure information including at least one of exposure energy information, exposure time information, exposure field position information, exposure field sequencing information, and exposure field deformation information;

measuring attributes of said fields to assess deformation of said fields induced by thermal effects of said exposing;

determining corrective information based on said measured attributes;

adjusting said pre-specified exposure information deformation effects based on said corrective information, to compensate for the thermally-induced field deformations;

providing a model to predict thermally-induced field deformation information; and

modifying said pre-specified exposure information prior to exposing, based on said predicted thermally-induced deformation information wherein said predicted thermally-induced field deformation includes predicting deformation effects of selected points within each of said fields based on a global expansion model.

2. The method of claim 1, wherein said predictive model is based on:

3. The method of claim 2, wherein said adjusting said pre-specified exposure information includes adjusting said exposure field sequencing information based on said predicted thermally-induced field deformation information.

4. A method of correcting thermally-induced field deformations of a lithographically exposed substrate, comprising:

exposing a pattern onto a plurality of fields of a substrate in accordance with pre-specified exposure information including at least one of exposure energy information, exposure time information, exposure field position information, exposure field sequencing information, and exposure field deformation information;

measuring attributes of said fields to assess deformation of said fields induced by thermal effects of said exposing;

determining corrective information based on said measured attributes;

adjusting said pre-specified exposure information deformation effects based on said corrective information, to compensate for the thermally-induced field deformations;

providing a model to predict thermally-induced field deformation information; and

modifying said pre-specified exposure information prior to exposing, based on said predicted thermally-induced deformation information wherein said thermally-induced field deformation includes predicting deformation effects of selected points within each of said fields based on a time-decay characteristic as energy is transported across the wafer.

5. The method of claim 4, wherein said predictive model is based on:

dx_p=Σ

_iT_i^xD_i^x; and

dy_p=Σ

_iT_i^yD_i^y;

where

6. The method of claim 5, wherein said adjusting said pre-specified exposure information includes adjusting said exposure field sequencing information based on said predicted thermally-induced field deformation information.

7. A method of correcting thermally-induced field deformations of a lithographically exposed substrate, comprising:

exposing a pattern onto a plurality of fields of a substrate in accordance with pre-specified exposure information at least one of exposure energy information, exposure time information, exposure field position information, exposure field sequencing information, and exposure field deformation information;

measuring attributes of said fields to assess deformation of said fields induced by thermal effects of said exposing;

determining corrective information based on said measured attributes;

adjusting said pre-specified exposure information, based on said corrective information, to compensate for the thermally-induced field deformations;

measuring temperature variations on surface of said substrate prior to exposing; and

generating a deformation map based on said measured substrate temperature variations.

8. The method of claim 7, further including modifying said pre-specified exposure information, prior to exposing, based on said deformation map.

9. The method of claim 8, wherein said temperature variation measurement includes thermographic imaging.

10. The method of claim 7, wherein said deformation map is characterized by:

11. The method of claim 8, wherein said adjusting said pre-specified exposure information includes adjusting said modified pre-specified exposure information, after said exposing, based on deformation offset information determined by said corrective information.

12. A method of correcting thermally-induced field deformations of a lithographically exposed substrate, comprising:

providing a model to predict deformation of a plurality of fields of a substrate induced by thermal effects of exposing;

modifying exposure information used to configure the exposure of said fields of said substrate based on said predicted thermally-induced deformation information;

exposing a pattern onto said fields of said substrate in accordance with said modified exposure information;

measuring attributes of said fields to assess deformation of said fields induced by thermal effects of said exposing;

determining corrective information based on said measured attributes; and

adjusting said modified exposure information, based on said corrective information, to compensate for the thermally-induced field deformations, wherein said predicted thermally-induced field deformation information includes predicting deformation effects of selected points within each of said fields based on a global expansion model.

13. The method of claim 12, wherein said predictive model is based on:

14. The method of claim 13, wherein said adjusting said pre-specified exposure information includes adjusting said exposure field sequencing information based on said predicted thermally-induced field deformation information.

15. A method of correcting thermally-induced field deformations of a lithographically exposed substrate, comprising:

providing a model to predict deformation of a plurality of fields of a substrate induced by thermal effects of exposing;

modifying exposure information used to configure the exposure of said fields of said substrate based on said predicted thermally-induced deformation information;

exposing a pattern onto said fields of said substrate in accordance with said modified exposure information;

measuring attributes of said fields to assess deformation of said fields induced by thermal effects of said exposing;

determining corrective information based on said measured attributes; and

adjusting said modified exposure information, based on said corrective information, to compensate for the thermally-induced field deformations, wherein said thermally-induced field deformation information includes predicting deformation effects of selected points within each of said fields based on a time-decaying characteristic as energy is transported across said wafer.

16. The method of claim 15, wherein said predictive model is based on:

dx_p=Σ

_iT_i^xD_i^x; and

dy_p=Σ

_iT_i^yD_i^y;

where

17. The method of claim 16, wherein said adjusting said pre-specified exposure information includes adjusting said exposure field sequencing information based on said predicted thermally-induced field deformation information.

18. A method of correcting thermally-induced field deformations of a lithographically exposed substrate, comprising:

measuring temperature variations on surface of a substrate containing a plurality of fields to be exposed;

generating a deformation map based on said measured substrate temperature variations;

modifying exposure information used to configure the exposure of said fields of said substrate based on said deformation map;

exposing a pattern onto said fields in accordance with said modified exposure information;

measuring attributes of said fields to assess deformation of said fields induced by thermal effects of said exposing;

determining corrective information based on said measured attributes; and

adjusting said modified exposure information, based on said corrective information, to compensate for the thermally-induced field deformations, wherein said temperature variation measurement includes thermographic imaging.

19. A method of correcting thermally-induced field deformations of a lithographically exposed substrate, comprising:

measuring temperature variations on surface of a substrate containing a plurality of fields to be exposed;

generating a deformation map based on said measured substrate temperature variations;

modifying exposure information used to configure the exposure of said fields of said substrate based on said deformation map;

exposing a pattern onto said fields in accordance with said modified exposure information;

measuring attributes of said fields to assess deformation of said fields induced by thermal effects of said exposing;

determining corrective information based on said measured attributes; and

adjusting said modified exposure information, based on said corrective information wherein said deformation map is characterized by;

20. The method of claim 19, wherein said adjusting said pre-specified exposure information includes adjusting said modified pre-specified exposure information, after said exposing, based on deformation offset information determined by said corrective information.

21. A method of correcting thermally-induced field deformations of substrates exposed by a lithographic apparatus, said method comprising:

determining corrective information based on exposed target fields of at least one prior substrate;

applying said corrective information to exposure information; and

exposing target fields of subsequent substrates in accordance with said exposure information having applied corrective information, wherein said determining corrective information includes exposing a pattern onto a plurality of said target fields of said at least one prior substrate and measuring attributes of said target fields of said at least one prior substrate to assess deformation induced by thermal effects of said exposing and wherein said determining corrective information includes deriving a thermal corrective model characterized by;

22. A method of correcting thermally-induced field deformations of substrates exposed by a lithographic apparatus, said method comprising:

determining corrective information based on exposed target fields of at least one prior substrate;

applying said corrective information to exposure information; and

exposing target fields of subsequent substrates in accordance with said exposure information having applied corrective information, wherein said determining corrective information includes exposing a pattern onto a plurality of said target fields of said at least one prior substrate and measuring attributes of said target fields of said at least one prior substrate to assess deformation induced by thermal effects of said exposing and said determining corrective information includes employing a predictive model characterized by;

23. A method of correcting thermally-induced field deformations of substrates exposed by a lithographic apparatus, said method comprising:

determining corrective information based on exposed target fields of at least one prior substrate;

applying said corrective information to exposure information; and

exposing target fields of subsequent substrates in accordance with said exposure information having applied corrective information, wherein said determining corrective information includes exposing a pattern onto a plurality of said target fields of said at least one prior substrate and measuring attributes of said target fields of said at least one prior substrate to assess deformation induced by thermal effects of said exposing and said determining corrective information includes employing a predictive model characterized by;

dx_p=Σ

_iT_i^xD_i^x; and

dy_p=Σ

_iT_i^yD_i^y;

where

24. A method of correcting thermally-induced field deformations of substrates exposed by a lithographic apparatus, said method comprising:

determining corrective information based on exposed target fields of at least one prior substrate;

applying said corrective information to exposure information; and

exposing target fields of subsequent substrates in accordance with said exposure information having applied corrective information, wherein said determining corrective information includes exposing a pattern onto a plurality of said target fields of said at least one prior substrate and measuring attributes of said target fields of said at least one prior substrate to assess deformation induced by thermal effects of said exposing and said determining corrective information comprises;

measuring temperature variations on surface of said at least one prior substrate, and

generating a deformation map based on said measured substrate temperature variations,

wherein said deformation map is characterized by;