Film coated optical lithography elements and method of making

• US 20030021015A1
• Filed: 09/09/2002
• Published: 01/30/2003
• Est. Priority Date: 04/07/2000
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Smith, Charlene M., Maier, Robert L., Moore, Lisa A.
• Granted Patent: US 6,833,949 B2
• Time in Patent Office: Days
• US Class Current: 359/350
• CPC Class Codes: C03B 19/1453 Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering
• CPC Class Codes: C03B 19/1461 for doping the shaped article with flourine
• CPC Class Codes: C03B 2201/075 Hydroxyl ion (OH)
• CPC Class Codes: C03B 2201/12 doped with fluorine C03B2201/14 takes precedence
• CPC Class Codes: C03C 17/02 with glass C03C17/34, C03C17/44 take precedence
• CPC Class Codes: C03C 17/3452 comprising a fluoride
• CPC Class Codes: C03C 2201/12 containing fluorine C03C2201/14 takes precedence
• CPC Class Codes: C03C 2201/23 containing hydroxyl groups
• CPC Class Codes: C03C 2203/46 fluorine containing
• CPC Class Codes: C03C 3/06 with more than 90% silica by weight, e.g. quartz C03C3/045 takes precedence
• CPC Class Codes: G02B 1/105 Protective coatings
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 5/208 for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
• CPC Class Codes: G03F 7/70958 Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties

Abstract

The invention provides coated optical lithography elements and methods of coating optical elements, and particularly optical photolithography elements for use in below 240 nm optical photolithography systems utilizing vacuum ultraviolet light (VUV) lithography wavelengths no greater than about 193 nm, such as VUV projection lithography systems utilizing wavelengths in the 193 nm or 157 nm region. The optical devices manipulate vacuum ultraviolet lithography light less than 250 nm utilizing a deposited silicon oxyfluoride film. The deposited silicon oxyfluoride optical coating assists in the manipulation of incident light and protects the underlying optical materials, layers, and surfaces.

Claims

1. A method of making an optical lithography device for manipulating ultraviolet light said method comprising:

providing an optical surface;

providing a silicon oxyhalide film preform precursor;

forming an optical coating on said optical surface, said optical coating formed on said optical surface from said provided silicon oxyhalide film preform.

2. A method as claimed in claim 1 wherein providing a silicon oxyhalide film preform comprises providing a silicon oxyhalide film preform glass.

3. A method as claimed in claim 2 wherein providing a silicon oxyhalide film preform glass comprises providing a silicon oxyfluoride glass.

4. A method as claimed in claim 3 wherein said silicon oxyfluoride glass has an internal transmission of at least 80%/cm at 193 nm.

5. A method as claimed in claim 3 wherein said silicon oxyfluoride glass has an internal transmission of at least 80%/cm at 157 nm.

6. A method as claimed in claim 3 wherein said silicon oxyfluoride glass has an internal transmission of at least 80%/cm at 175 nm.

7. A method as claimed in claim 3 wherein said silicon oxyfluoride glass has a fluorine content of at least 0.1 weight percent.

8. A method as claimed in claim 3 wherein said silicon oxyfluoride glass has a fluorine content of 0.1 to 2 weight percent

9. A method as claimed in claim 3 wherein said silicon oxyfluoride glass has an OH content below 50 ppm by weight.

10. A method as claimed in claim 3 wherein said silicon oxyfluoride glass has an OH content below 10 ppm by weight.

11. A method as claimed in claim 3 wherein said silicon oxyfluoride glass has a chlorine content below 5 ppm by weight.

12. A method as claimed in claim 3 wherein said silicon oxyfluoride glass consists essentially of Si, O and F.

13. A method as claimed in claim 1 wherein said formed optical coating comprises a silicon oxyfluoride film.

14. A method as claimed in claim 13 wherein said optical silicon oxyfluoride coating has a fluorine content of at least 0.05 weight percent.

15. A method as claimed in claim 13 wherein said optical silicon oxyfluoride coating has a fluorine content from 0.1 to 2 weight percent.

16. A method as claimed in claim 13 wherein said optical silicon oxyfluoride coating has an OH content below 50 ppm by weight.

17. A method as claimed in claim 13 wherein said optical silicon oxyfluoride coating has an OH content below 10 ppm by weight.

18. A method as claimed in claim 13 wherein said silicon oxyfluoride optical coating has a chlorine content below 5 ppm by weight.

19. A method as claimed in claim 13 wherein said silicon oxyfluoride optical coating consists essentially of Si, O and F.

20. A method as claimed in claim 1 wherein providing a silicon oxyhalide film preform comprises providing a silicon oxyfluoride film preform glass which has a fluorine content of 0.1 to 2 weight percent and forming an optical coating comprises forming a silicon oxyfluoride coating which has a fluorine content of 0.05 to 1.5 weight percent.

21. A method as claimed in claim 1 wherein forming an optical coating comprises forming an optical coating with a packing density >

0.9.

22. A method as claimed in claim 1 wherein forming an optical coating comprises forming an optical coating with a packing density ≧

0.95.

23. A method as claimed in claim 1 wherein forming an optical coating comprises forming an optical coating with a packing density ≧

0.98 .

24. A method as claimed in claim 1 wherein forming an optical coating comprises forming a non-crystalline amorphous film.

25. A method as claimed in claim 1 wherein said film has an internal transmission of at least 80%/cm at UV lithography light wavelengths below 200 nm.

26. A method as claimed in claim 1, wherein said optical coating is damage resistant to below 200 nm lithography light exposure.

27. A method as claimed in claim 1 wherein forming an optical coating includes forming a vacuum and depositing said optical coating in said vacuum.

28. A method as claimed in claim 27 wherein depositing said optical coating includes vapor depositing said optical coating onto said optical surface.

29. A method as claimed in claim 1, further comprising:

providing an optical film deposition vacuum chamber;

evacuating said vacuum chamber to form an evacuated vacuum atmosphere containing said optical surface and said silicon oxyhalide film preform;

vaporizing said silicon oxyhalide film preform and depositing a film from said vaporized silicon oxyhalide film preform onto said optical surface to form said optical coating.

30. A method as claimed in claim 1 wherein providing an optical surface comprises providing an optical substrate.

31. A method as claimed in claim 1 wherein providing an optical surface comprises providing a deposited optical film on an optical substrate.

32. A method as claimed in claim 1 wherein forming an optical coating comprises forming a thin transparent optical interference film for controlling reflection of incident radiation.

33. A method as claimed in claim 1 wherein forming an optical coating comprises forming a thin transparent optical interference film for controlling transmission of incident radiation.

34. A method as claimed in claim 1 wherein forming an optical coating comprises forming a thin transparent optical interference film for separating wavelengths of incident radiation.

35. A method as claimed in claim 1 wherein forming an optical coating comprises forming a thin transparent optical interference film for dividing the amplitudes of incident radiation.

36. A method as claimed in claim 1 wherein forming an optical coating comprises forming a thin transparent optical interference film for separating the polarization states of incident radiation.

37. A method as claimed in claim 1 wherein providing an optical surface comprises providing a silica glass optical substrate lithography element.

38. A method as claimed in claim 1 wherein providing an optical surface comprises providing a calcium fluoride optical substrate lithography element.

39. A method as claimed in claim 1 wherein providing an optical surface comprises providing a fluoride crystal optical substrate lithography element.

40. A method as claimed in claim 1 wherein forming an optical coating includes ion bombarding said silicon oxyhalide film preform.

41. A method as claimed in claim 1 wherein forming an optical coating includes heating said optical surface.

42. A method as claimed in claim 1 wherein said optical surface is unheated.

43. A method as claimed in claim 3 wherein said silicon oxyhalide film preform silicon oxyfluoride glass has a fluorine content FB and said formed optical coating has a fluorine content FA with FA>

0.25 FB.

44. A method as claimed in claim 1 wherein said silicon oxyhalide glass film preform has a fluorine content FB and said formed optical coating has a fluorine content FA with FA≧

0.35 FB.

45. A method as claimed in claim 1, said optical surface having a hardness S and said formed optical coating having a hardness H wherein said hardness H is greater than said hardness S.

46. A method as claimed in claim 1, wherein said silicon oxyhalide glass film preform is non-hygroscopic and said optical surface is hygroscopic.

47. A method as claimed in claim 1, said optical surface having a porosity P and said formed optical coating having a porosity NP wherein P>

NP.

48. A method-as claimed in claim 1 wherein providing an optical surface includes providing an optical substrate, forming a vacuum, depositing a fluoride film on said optical substrate in said vacuum to form said optical surface and than maintaining said vacuum while forming said optical coating on said deposited fluoride film optical surface.

49. A below 240 nm optical lithography device for manipulating below 240 nm wavelength optical lithography radiation having a wavelength band centered about λ

, said device comprising an optical lithography element body, said optical lithography element body comprised of an optical lithography medium having a λ

internal transmission of at least 80%/cm, and an optical lithography coating overlaying said optical lithography element, said optical coating comprised of a silicon oxyfluoride film, said silicon oxyfluoride film having a 50% transmission short cut off wavelength, said 50% transmission cut off wavelength less than λ

.

50. A device as claimed in claim 49 wherein the thickness of said silicon oxyfluoride film correlates to the wavelength band centered about λ

.

51. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a thickness TH with TH<

2λ

.

52. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a thickness TH with TH≦

λ

.

53. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a thickness TH, with TH=(1/N) λ

where N is a whole number greater than one.

54. A device as claimed in claim 53 wherein N is four.

55. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a thickness TH=P(λ

/4) where P is a whole number greater than zero.

56. A device as claimed in claim 49 wherein said optical coating is a vapor deposited silicon oxyfluoride film.

57. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a fluorine content of 0.1 to 2 weight percent.

58. A device as claimed in claim 49 wherein said silicon oxyfluoride film consists essentially of Si, O and F.

59. A device as claimed in claim 49 wherein said silicon oxyfluoride film has an OH content below 50 ppm by weight.

60. A device as claimed in claim 49 wherein said silicon oxyfluoride film an OH content below 10 ppm by weight.

61. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a chlorine content below 5 ppm by weight.

62. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a fluorine content of at least 0.05 weight percent.

63. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a fluorine content of at least 0.1 weight percent.

64. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a fluorine content of at least 0.3 weight percent.

65. A device as claimed in claim 49 wherein said silicon oxyfluoride film has a fluorine content of at least 0.4 weight percent.

66. A device as claimed in claim 49 wherein said silicon oxyfluoride film is vapor deposited from a silicon oxyfluoride glass which has an internal transmission of at least 80%/cm at 193 nm.

67. A device as claimed in claim 49 wherein said silicon oxyfluoride film is vapor deposited from a silicon oxyfluoride glass which has an internal transmission of at least 80%/cm at 157 nm.

68. A device as claimed in claim 49 wherein λ

=193 nm.

69. A device as claimed in claim 49 wherein λ

=157 nm.

70. A device as claimed in claim 49 wherein said optical lithography medium is comprised of Si.

71. A device as claimed in claim 49 wherein said optical lithography medium is comprised of SiO₂.

72. A device as claimed in claim 49 wherein said optical lithography medium is comprised of silica glass.

73. A device as claimed in claim 49 wherein said optical lithography medium is comprised of silicon oxyfluoride glass.

74. A device as claimed in claim 49 wherein said optical lithography medium is comprised of a fluoride crystal.

75. A device as claimed in claim 49 wherein said optical lithography medium is comprised of a calcium fluoride crystal.

76. A device as claimed in claim 49 wherein said optical lithography device comprises at least a second film.

77. A method of making an optical element for manipulating below 250 nm light, said method comprising:

providing an optical surface for manipulating below 250 nm photons;

providing a silicon oxyfluoride glass;

vaporizing said provided silicon oxyfluoride glass,

depositing said vaporized silicon oxyfluoride glass on said optical surface.

78. A method as claimed in claim 77, wherein vaporizing said provided silicon oxyfluoride glass comprises energetic ion bombarding said provided silicon oxyfluoride glass.

79. A method as claimed in claim 77, wherein depositing includes maintaining a vacuum and depositing a thin transparent optical interference silicon oxyfluoride film on said optical surface.

80. A method as claimed in claim 77, wherein depositing includes maintaining a vacuum and forming a protective optical silicon oxyfluoride coating film on said optical surface.

81. A method as claimed in claim 77, further comprised of heating said provided optical surface.

82. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a silicon oxyfluoride glass with a fluorine content of at least 0.1 weight %.

83. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a silicon oxyfluoride glass with a 157 nm internal transmission of at least 80%/cm.

84. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a silicon oxyfluoride glass with an internal transmission in the wavelength range of 157 nm to 175 nm of at least 80%/cm.

85. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass which has an increase of absorption at 215 nm of less than 0.1 optical density (log₁₀ transmission) per mm when exposed to at least 0.96×

10⁶ pulses of 157 nm wavelength containing F₂ excimer laser radiation at 4 mJ/cm²—

pulse.

86. A method as claimed in claim 85, wherein said increase of absorption at 215 nm is less than 0.05 optical density.

87. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a silicon oxyfluoride glass having an OH content less than 5 ppm by weight, a Cl content less than 5 ppm by weight, a H₂ content less than 1×

10¹⁷ molecules/cm³, and fluorine content of at least 0.1 weight %, said glass having a 157 nm internal transmission of at least 80%/cm.

88. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a silicon oxyfluoride glass which has a coefficient of thermal expansion less than 0.55 ppm/°

C. in the temperature range from room temperature to 300°

C.

89. A method as claimed in claim 87, wherein said Cl content is less than 1 ppm and said OH content is less than 1 ppm.

90. A method as claimed in claim 87, wherein said glass consists essentially of Si, O and F.

91. A method as claimed in claim 87, wherein said glass is essentially free of metal to metal Si—

Si bonds.

92. A method as claimed in claim 91 wherein said glass is free of a 165 nm absorbing center and has an internal transmission at 165 nm of at least 85%/cm.

93. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a VUV cut off wavelength lowered silicon oxyfluoride glass with a 50% transmission VUV cut off wavelength below 160 nm.

94. A method as claimed in claim 93, wherein said silicon oxyfluoride glass consists essentially of Si, O and F and is essentially free of Si—

Si bonds.

95. A method as claimed in claim 93, wherein said silicon oxyfluoride glass has an OH content less than 1 ppm by weight and a chlorine content no greater than 25 ppm by weight.

96. A method as claimed in claim 95, wherein said silicon oxyfluoride glass has a fluorine concentration greater than about 0.1 wt. %.

97. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a vaporizable silicon oxyfluoride film precursor preform glass target.

98. A method as claimed in claim 97, wherein said vaporizable silicon oxyfluoride film precursor preform glass target is a chlorine dried helium flushed silicon oxyfluoride glass.

99. A method as claimed in claim 98, wherein said chlorine dried helium flushed silicon oxyfluoride glass is a chlorine dried helium and fluorine flushed silicon oxyfluoride glass.

100. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a silicon oxyfluoride glass with an OH content less than 50 ppm and a fluorine concentration greater than about 0.5 wt. %.

101. A method as claimed in claim 77, wherein providing a silicon oxyfluoride glass comprises providing a silicon oxyfluoride glass with an OH content less than 10 ppm.

102. A method as claimed in claim 100, wherein said OH content <

5 ppm.

103. A method as claimed in claim 100, wherein said OH content <

1 ppm.

104. A method of making a silicon oxyfluoride film precursor preform glass vaporization target, comprising the steps of:

providing a plurality of particles of SiO₂, doping the particles with a plurality of fluorine, and consolidating the particles to form a fused silicon oxyfluoride glass.

105. A method as claimed in claim 104, wherein providing particles of SiO₂ comprises delivering a Si containing feedstock to a conversion site, and converting the Si containing feedstock into said particles.

106. A method as claimed in claim 105, wherein doping the particles with fluorine includes delivering a F containing feedstock to said conversion site and doping said particles concurrently with converting the Si containing feedstock into said particles.

107. A method as claimed in claim 104, wherein doping the particles with fluorine includes flooding the particles with a fluorine containing gas.

108. A method as claimed in claim 104, further comprising flooding the particles with a fluorine containing gas and sintering the particles in a fluorine containing gas atmosphere.

109. A method as claimed in claim 104, further comprising dehydrating said particles.

110. A silicon oxyfluoride film precursor preform glass vaporization target for forming a silicon oxyfluoride film, said film precursor comprised of a silicon oxyfluoride glass, said silicon oxyfluoride glass having a fluorine content of at least 0.1 weight percent, said glass having an internal transmission of at least 80%/cm in the wavelength range of 157 nm to 175 nm.

111. A film precursor glass as claimed in claim 110, wherein said glass has an increase of absorption at 215 nm of less than 0.1 optical density per mm when exposed to at least 0.96×

10⁶ pulses of 157 nm wavelength containing excimer laser radiation at 4 mJ/cm²—

pulse.

112. A film precursor glass as claimed in claim 110, wherein said glass has an OH content less than 10 ppm by weight, a chlorine content no greater than 25 ppm, and a F content ≧

1 weight percent.

113. A film precursor glass as claimed in claim 110, wherein said glass has a coefficient of thermal expansion less than 0.55 ppm/°

C. in the temperature range from room temperature to 300°

C.

114. A film precursor glass as claimed in claim 110, wherein said glass consists essentially of Si, O and F.

115. A film precursor glass as claimed in claim 110, wherein said glass is free of a 165 nm absorbing center and has an internal transmission at 165 nm of at least 85%/cm.

116. A film precursor glass as claimed in claim 110, wherein said glass having a 435.8 nm refractive index ≦

1.466.

117. A film precursor glass as claimed in claim 110, wherein said glass having a 435.8 nm refractive index ≦

1.465.

118. A film precursor glass as claimed in claim 110, wherein said glass having a 435.8 nm refractive index ≦

1.464.

119. A film precursor glass as claimed in claim 110, having a 10^{13 2} poise viscosity anneal point temperature less than 1000°

C.

120. A film precursor glass as claimed in claim 110, having a 10^14.7 poise viscosity strain point temperature less than 850°

C.