Photomask, method of producing it and pattern forming method using the photomask

• US 20040121244A1
• Filed: 10/08/2003
• Published: 06/24/2004
• Est. Priority Date: 12/26/2001
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Misaka, Akio
• Granted Patent: US 7,060,398 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 1/30 Alternating PSM, e.g. Levenson-Shibuya 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 to be provided on a transparent substrate 2 includes a semi-light-shielding portion 3 which transmits exposure light in the same phase as that of the light-transmitting portion 4 and a phase shifter 5 which transmits exposure light in a phase opposite to that of the light-transmitting portion 4. The semi-light-shielding portion 3 has a transmittance which allows exposure light to be partially transmitted. The phase shifter 5 is provided in a region of the mask pattern in which light transmitted through the phase shifter 5 can cancel part of the light transmitted through the light-transmitting portion 4 and the semi-light-transmitting portion 3.

Claims

1. A photomask in which, on a transparent substrate having light transmitting properties with respect to exposure light, a mask pattern having light-shielding properties with respect to the exposure light and a light-transmitting portion of the transparent substrate where the mask pattern is not located are provided, characterized in that

the mask pattern includes:

a semi-light-shielding portion which transmits the exposure light in the same phase as that of the light-transmitting portion; and

a phase shifter which transmits the exposure light in a phase opposite to that of the light-transmitting portion,

the semi-light-shielding portion has a transmittance which allows the exposure light to be partially transmitted, and

the phase shifter is provided in a region of the mask pattern in which light transmitted through the phase shifter can cancel part of light transmitted through the light-transmitting portion and the semi-light-transmitting portion.

2. The photomask of claim 1, characterized in that the transmittance of the semi-light-transmitting portion with respect to the exposure light is 15% or less.

3. The photomask of claim 1, characterized in that the transmittance of the semi-light-transmitting portion with respect to the exposure light is 6% or more and 15% or less.

4. The photomask of claim 1, characterized in that the semi-light-shielding portion transmits the exposure light with a phase difference of (−

30+360×

n) degrees or more and (30+360×

n) degrees or less (where n=an integer) with respect to light transmitted through the light-transmitting portion, and the phase shifter transmits the exposure light with a phase difference of (150+360×

n) degrees or more and (210+360×

n) degrees or less (where n=an integer) with respect to light transmitted through the light-transmitting portion.

5. The photomask of claim 1, characterized in that the phase shifter is disposed in a region of the mask pattern extending from the boundary with the light-transmitting portion by a distance of (0.8×

λ

/NA)×

M or less (where λ

is the wavelength of the exposure light, and NA and M are the numerical aperture and reduction ratio of a reduction projection optical system of an exposure apparatus, respectively).

6. The photomask of claim 1, characterized in that the width of the phase shifter is (0.3×

λ

/NA)×

M or less (where λ

is the wavelength of the exposure light, and NA and M are the numerical aperture and reduction ratio of a reduction projection optical system of an exposure apparatus, respectively).

7. The photomask of claim 1, characterized in that

the mask pattern is provided so as to surround the light-transmitting portion, and the phase shifter is provided in the vicinity of the light-transmitting portion of the mask pattern so as to be interposed between the semi-light-transmitting portion and the light-transmitting portion.

8. The photomask of claim 1, characterized in that

the mask pattern is provided so as to surround the light-transmitting portion, and

the phase shifter is provided in the vicinity of the light-transmitting portion of the mask pattern so as to be surrounded by the semi-light-transmitting portion.

9. The photomask of claim 1, characterized in that

the mask pattern is surrounded by the light-transmitting portion, and

the phase shifter is surrounded by the semi-light-transmitting portion.

10. The photomask of claim 9, characterized in that the width of the mask pattern is (0.8×

λ

/NA)×

M or less (where λ

is the wavelength of the exposure light, and NA and M are the numerical aperture and reduction ratio of a reduction projection optical system of an exposure apparatus, respectively).

11. The photomask of claim 10, characterized in that the width of the phase shifter is (0.4×

λ

/NA)×

M or less.

12. The photomask of claim 1, characterized in that

the mask pattern is a line-shaped pattern surrounded by the light-transmitting portion, and

the phase shifter is provided in a center portion of the mask pattern in the line width direction so as to be interposed between parts of the semi-light-shielding portion.

13. The photomask of claim 12, characterized in that the width of the mask pattern is (0.8×

λ

/NA)×

M or less (where λ

is the wavelength of the exposure light, and NA and M are the numerical aperture and reduction ratio of a reduction projection optical system of an exposure apparatus, respectively).

14. The photomask of claim 13, characterized in that the width of the phase shifter is (0.4×

λ

/NA)×

M or less.

15. The photomask of claim 1, characterized in that

the mask pattern is a line-shaped pattern surrounded by the light-transmitting portion, and

the phase shifter is provided at least in each of both end portions of the mask pattern in the line width direction so that the semi-light-shielding portion is interposed between phase shifters.

16. The photomask of claim 1, characterized in that

the mask pattern is a line-shaped pattern surrounded by the light-transmitting portion, and

the phase shifter is provided in each of both end portions and center portion of the mask pattern in the line width direction so that the semi-light-shielding portion is interposed between phase shifters.

17. The photomask of claim 16, characterized in that

the width of the mask pattern is (λ

/NA)×

M or less (where λ

is the wavelength of the exposure light, and NA and M are the numerical aperture and reduction ratio of a reduction projection optical system of an exposure apparatus, respectively).

18. The photomask of claim 17, characterized in that the width of the phase shifter is (0.3×

λ

/NA)×

M or less.

19. The photomask of claim 1, characterized in that

the mask pattern is a line-shaped pattern surrounded by the light-transmitting portion, and

the phase shifter is provided in each of both end portions of the mask pattern in the line width direction so as to be surrounded by the semi-light-shielding portion.

20. The photomask of claim 1, characterized in that

the mask pattern is a line-shaped pattern surrounded by the light-transmitting portion, and

the phase shifter is provided in each of both end portions and center portion of the mask pattern in the line width direction so as to be surrounded by the semi-light-shielding portion.

21. The photomask of claim 1, characterized in that

the light-transmitting portion includes a first light-transmitting portion and a second light-transmitting portion,

the mask pattern is provided so as to surround the first light-transmitting portion and the second light-transmitting portion,

the phase shifter is provided in a center portion of the mask pattern located between the first light-transmitting portion and the second light-transmitting portion, and the semi-light shielding portion is provided in each of both sides of the phase shifter.

22. The photomask of claim 21, characterized in that the space between the first light-transmitting portion and the second light-transmitting portion is (0.8×

λ

/NA)×

M or less (where λ

is the wavelength of the exposure light, and NA and M are the numerical aperture and reduction ratio of a reduction projection optical system of an exposure apparatus, respectively).

23. The photomask of claim 22, characterized in that the width of the phase shifter is (0.4×

λ

/NA)×

M or less.

24. A method for forming a pattern using the photomask of claim 1, characterized by comprising the steps of:

forming a resist film on a substrate;

irradiating the resist film with the exposure light through the photomask; and

developing the resist film which has been irradiated with the exposure light to form a resist pattern.

25. The method for forming a pattern of claim 24, characterized in that in the step of irradiating the exposure light, an off-axis illumination method is used.

26. A method for generating mask data for the photomask of claim 1, characterized by comprising:

a first step of determining the shape of a mask pattern based on a pattern to be formed using the photomask and setting the transmittance of the semi-light-shielding portion;

a second step, after the first step, of extracting a region of the mask pattern having a predetermined dimension or less and interposed between parts of the light-transmitting portion; and

a third step, after the second step, of inserting the phase shifter in each of the extracted region and part of the mask pattern located in the vicinity of the light-transmitting portion.

27. The method for generating mask data of claim 26, characterized by further comprising:

after the third step,

the step of inserting the semi-light-shielding portion having a predetermined dimension or less between the phase shifter and the light-transmitting portion.

28. The method for generating mask data of claim 26, characterized by further comprising:

after the third step,

the step of inserting another phase shifter which transmits the exposure light in a phase opposite to that of the light-transmitting portion in a region of the mask pattern having a predetermined dimension or less and interposed between parts of the light-transmitting portion.

29. The method for generating mask data of claim 28, characterized in that said another phase shifter transmits the exposure light with a phase difference of (150+360×

n) degrees or more and (210+360×

n) degrees or less (where n=an integer) with respect to light transmitted through the light-transmitting portion.

30. The method for generating mask data of claim 26, characterized by further comprising:

after the third step,

the step of extracting an end portion of a line-shaped pattern having a width equal to or smaller than a predetermined dimension from the mask pattern and then inserting another phase shifter in part of the periphery of the extracted end portion extending in parallel to the line direction.

31. The method for generating mask data of claim 26, characterized by further comprising:

after the third step,

the step of extracting a corner from the mask pattern and then, if the phase shifter is disposed in a region of the mask pattern extending from a bent point of the extracted corner by a predetermined dimension or less, replacing the phase shifter with the semi-light-shielding portion or reducing a dimension of the phase shifter.

32. The method for generating mask data of claim 26, characterized by further comprising:

after the third step,

the step of correcting a dimension of the semi-light-shielding portion with a dimension of the phase shifter fixed so that the pattern to be formed using the photomask has a desired dimension.

33. A method for generating mask data for the photomask of claim 1, characterized by comprising:

a first step of determining the shape of a mask pattern based on a pattern to be formed using the photomask and setting the transmittance of the semi-light-shielding portion;

a second step, after the first step, of extracting a region of the mask pattern having a width equal to or less than a predetermined dimension; and

a third step, after the second step, of inserting the phase shifter in each of the extracted region and the periphery of a region of the mask pattern having a larger width than the predetermined dimension.

34. The method for generating mask data of claim 33, characterized by further comprising:

after the third step,

the step of inserting the semi-light-shielding portion having a predetermined dimension or less between the phase shifter and the light-transmitting portion.

35. The method for generating mask data of claim 33, characterized by further comprising:

after the third step,

the step of inserting another phase shifter which transmits the exposure light in a phase opposite to that of the light-transmitting portion in a region of the mask pattern having a larger width than a predetermined dimension.

36. The method for generating mask data of claim 35, characterized in that said another phase shifter transmits the exposure light with a phase difference of (150+360×

n) degrees or more and (210+360×

n) degrees or less (where n=an integer) with respect to light transmitted through the light-transmitting portion.

37. The method for generating mask data of claim 33, characterized by further comprising:

after the third step,

the step of extracting an end portion of a line-shaped pattern having a width equal to or smaller than a predetermined dimension from the mask pattern and then inserting another phase shifter in part of the periphery of the extracted end portion extending in parallel to the line direction.

38. The method for generating mask data of claim 33, characterized by further comprising:

after the third step,

the step of extracting a corner from the mask pattern and then, if the phase shifter is disposed in a region of the mask pattern extending from a bent point of the extracted corner by a predetermined dimension or less, replacing the phase shifter with the semi-light-shielding portion or reducing a dimension of the phase shifter.

39. The method for generating mask data of claim 33, characterized by further comprising:

after the third step,

the step of correcting a dimension of the semi-light-shielding portion with a dimension of the phase shifter fixed so that the pattern to be formed using the photomask has a desired dimension.