Photomask, Photomask Fabrication Method, Pattern Formation Method Using the Photomask and Mask Data Creation Method

• US 20080286661A1
• Filed: 02/27/2007
• Published: 11/20/2008
• Est. Priority Date: 03/06/2006
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Misaka, Akio
• Granted Patent: US 7,897,298 B2
• Time in Patent Office: Days
• US Class Current: 430/5
• CPC Class Codes: G03F 1/29 Rim PSM or outrigger PSM; Preparation thereof
• CPC Class Codes: G03F 1/32 Attenuating PSM [att-PSM], e.g. halftone PSM or PSM having semi-transparent phase shift portion,; Preparation thereof

Abstract

A mask pattern including a light-shielding portion 101 and a semi-light-shielding portion 102 is provided on a transparent substrate 100 having a transparent property against exposing light so as to be surrounded with a transparent portion 104. The semi-light-shielding portion 102 is disposed in an outer region of the mask pattern and partially transmits the exposing light in an identical phase to the exposing light passing through the transparent portion 104.

Claims

1. A photomask comprising a mask pattern provided on a transparent substrate having a transparent property against exposing light,

wherein said mask pattern includes a light-shielding portion and a semi-light-shielding portion,

a transparent portion having a transparent property against the exposing light and surrounding said mask pattern is provided on said transparent substrate, and

said semi-light-shielding portion is provided in at least a part of an outer region of said mask pattern and partially transmits the exposing light in an identical phase to the exposing light passing through said transparent portion.

2. The photomask of claim 1,

wherein said mask pattern at least includes a first pattern region having a first width and a second pattern region having a second width larger than said first width,

a phase shifter portion for transmitting the exposing light in an opposite phase to the exposing light passing through said transparent portion is provided in said first pattern region,

said light-shielding portion is provided in said second pattern region, and

said semi-light-shielding portion is provided in an outer region of at least said second pattern region.

3. The photomask of claim 2,

wherein said semi-light-shielding portion is provided in an outer region of said first pattern region.

4. The photomask of claim 2,

wherein said phase shifter portion is provided in such a manner as to be in contact with a given part of said light-shielding portion, and

said semi-light-shielding portion is provided in such a manner as to be in contact with a part of said light-shielding portion other than said given part.

5. The photomask of claim 2,

wherein said semi-light-shielding portion is not provided in at least a part of an outer region of said first pattern region.

6. The photomask of claim 2,

wherein said phase shifter portion and said light-shielding portion are in contact with each other and are together surrounded with said semi-light-shielding portion.

7. The photomask of claim 2,

wherein a part of said semi-light-shielding portion is sandwiched between said phase shifter portion and said light-shielding portion.

8. The photomask of claim 2,

wherein said phase shifter portion and said light-shielding portion are individually surrounded with said semi-light-shielding portion.

9. The photomask of claim 8,

wherein said semi-light-shielding portion includes at least one of a hammer-shaped pattern provided at an end of said phase shifter portion and a serif pattern provided at a corner of said light-shielding portion.

10. The photomask of claim 2,

wherein said semi-light-shielding portion is made of a semi-light-shielding film formed on said transparent substrate, and

said phase shifter portion is made of an opening formed in said semi-light-shielding film.

11. The photomask of claim 10,

wherein said transparent substrate is trenched within said opening formed as said phase shifter portion.

12. The photomask of claim 2,

wherein said phase shifter portion transmits the exposing light in a phase difference not less than (150+360×

n) degrees and not more than (210+360×

n) degrees with respect to said transparent portion (wherein n is an integer).

13. The photomask of claim 2,

wherein said first width is not more than M×

λ

/NA (wherein λ

indicates a wavelength of the exposing light and M and NA respectively indicate a reduction ratio and numerical aperture of a reduction projection optical system of a projection aligner).

14. The photomask of claim 1,

wherein said semi-light-shielding portion transmits the exposing light in a phase difference not less than (−

30+360×

n) degrees and not more than (30+360×

n) degrees with respect to said transparent portion (wherein n is an integer).

15. The photomask of claim 1,

wherein said semi-light-shielding portion has transmittance against the exposing light of 4% or more and 64% or less.

16. The photomask of claim 1,

wherein said semi-light-shielding portion has transmittance against the exposing light of 10% or more and 40% or less.

17. The photomask of claim 1,

wherein said semi-light-shielding portion is made of a metal thin film with a thickness of 30 nm or less.

18. The photomask of claim 1,

wherein said semi-light-shielding portion provided in said outer region of said mask pattern has a width not more than M×

λ

/NA (wherein λ

indicates a wavelength of the exposing light and M and NA respectively indicate a reduction ratio and numerical aperture of a reduction projection optical system of a projection aligner).

19. The photomask of claim 1,

wherein an additional semi-light-shielding portion is provided around said mask pattern with a part of said transparent portion sandwiched therebetween.

20. The photomask of claim 19,

wherein said part of said transparent portion sandwiched between said semi-light-shielding portion provided in said outer region of said mask pattern and said additional semi-light-shielding portion has a width not more than M×

λ

/NA (wherein λ

indicates a wavelength of the exposing light and M and NA respectively indicate a reduction ratio and numerical aperture of a reduction projection optical system of a projection aligner).

21. The photomask of claim 19,

wherein said additional semi-light-shielding portion has transmittance against the exposing light of 25% or more.

22. The photomask of claim 21,

wherein said additional semi-light-shielding portion has a width not less than M×

λ

/NA (wherein λ

indicates a wavelength of the exposing light and M and NA respectively indicate a reduction ratio and numerical aperture of a reduction projection optical system of a projection aligner).

23. The photomask of claim 1,

wherein said semi-light-shielding portion is provided in whole of said outer region of said mask pattern, and

said light-shielding portion is surrounded with said semi-light-shielding portion.

24. The photomask of claim 23,

wherein said mask pattern further includes an additional semi-light-shielding portion surrounded with said light-shielding portion.

25. The photomask of claim 23,

wherein said semi-light-shielding portion of said mask pattern has a periphery surrounded with said transparent portion, and

said transparent portion has a periphery surrounded with an additional semi-light-shielding portion provided on said transparent substrate.

26. The photomask of claim 23,

wherein said mask pattern is in a polygonal shape, and

respective sides of said mask pattern are surrounded with a plurality of rectangular patterns opposing said respective sides and corresponding to said transparent portion.

30. A method for fabricating the photomask of claim 2, comprising the steps of:

(a) successively forming a semi-light-shielding film and a light-shielding film on said transparent substrate;

(b) removing said semi-light-shielding film and said light-shielding film in a region for said transparent portion and in a region for said phase shifter portion;

(c) trenching said transparent substrate in the region for said phase shifter portion by a given depth after the step (b); and

(d) removing said light-shielding film in a region for said semi-light-shielding portion after the step (b).

31. A pattern formation method using the photomask of claim 1, comprising the steps of:

(a) forming a resist film on a substrate;

(b) irradiating said resist film with the exposing light through said photomask; and

(c) forming a resist pattern by developing said resist film having been irradiated with the exposing light.

32. The pattern formation method of claim 31,

wherein oblique incident illumination is employed in the step (b).

27. A photomask comprising a mask pattern surrounded with a reflection portion on a substrate,

wherein said mask pattern includes a non-reflection portion and a semi-reflection portion, and

said semi-reflection portion is provided in at least a part of an outer region of said mask pattern and partially reflects exposing light in an opposite phase to the exposing light reflected by said reflection portion.

28. The photomask of claim 27,

wherein said mask pattern includes at least a first pattern region having a first width and a second pattern region having a second width larger than said first width,

a phase shifter portion for reflecting the exposing light in an opposite phase to the exposing light reflected by said reflection portion is provided in said first pattern region,

said non-reflection portion is provided in said second pattern region, and

said semi-reflection portion is provided in an outer region of at least said second pattern region.

29. The photomask of claim 28,

wherein said semi-reflection portion is provided in an outer region of said first pattern region.

33. A mask data creation method for a photomask including a mask pattern formed on a transparent substrate having a transparent property against exposing light and a transparent portion of said transparent substrate where said mask pattern is not formed, comprising the steps of:

(a) creating a pattern corresponding to a desired unexposed region of a resist by irradiating said resist with the exposing light through said photomask;

(b) dividing said pattern into a first region having a width not larger than a given value and a second region having a width larger than said given value;

(c) providing, in said first region, a phase shifter portion for transmitting the exposing light in an opposite phase to the exposing light passing through said transparent portion;

(d) providing a light-shielding portion in said second region; and

(e) providing, in an outer region of said second region, a semi-light-shielding portion for partially transmitting the exposing light in an identical phase to the exposing light passing through said transparent portion.

34. The mask data creation method of claim 33, further comprising a step of providing said semi-light-shielding portion in an outer region of said first region.

35. The mask data creation method of claim 33, further comprising a step of creating a mask pattern for realizing a desired resist pattern by dividing and/or moving an outline of said semi-light-shielding portion after providing said semi-light-shielding portion.

36. The mask data creation method of claim 33, further comprising a step of providing an additional semi-light-shielding portion around said pattern with a part of said transparent portion sandwiched therebetween.