Silica with low compaction under high energy irradiation

Details Silica with low compaction under high energy irradiation Silica with low compaction under high energy irradiation

1999-02-25

2001-10-30

Group, Karl (Department: 1755)

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

C501S012000, C065S413000, C065S416000, C065S422000, C065S426000, C065S030100, C065S033200, C430S005000

Reexamination Certificate

active

06309991

ABSTRACT:

FIELD OF THE INVENTION
This application claims priority to U.S. provisionalapplication no. 60/024995, filed Aug. 29, 1996. The invention relates to stepper lens from fused silica having low compaction under high energy irradiation, particularly adaptable for use in photolithography applications at wavelengths of 193 and 248 nm.
BACKGROUND OF THE INVENTION
Fused silica is highly relevant to such applications as windows and mirrors used in outer space, and increasingly, it is becoming relevant to optical elements for deep ultraviolet photolithography. However, it is generally known that prolonged exposure of fused silica to intense deep ultraviolet radiation of the type utilized in photolithography leads to optical damage which is generally manifested in the form of changes in the optical and physical properties of the glass.
One form of optical damage observed in fused silica glass is a physical densification or compaction of the exposed regions of the glass. Compaction is generally observed by interferometry where the alteration of the optical phase front is measured through the damaged regions, and is reported as optical path difference, the product of refractive index and path length, in ppm or waves of 633 nm light. Thus, the optical phase front of stepper lens elements for photolithographic applications which utilize deep ultraviolet wavelengths at 193 and 248 nm for high resolution microcircuit fabrication may become altered due to optical modification as a consequence of prolonged exposure. Even though small changes in the optical phase front produced by the effect of exposure over the life of the lens barrel are expected, at present the maximum acceptable change is not known. What is known however, is that there is a relationship between alterations in fused silica and the ultimate effect of such changes on the wavefront.
The question of what factors contribute to the propensity of various silica materials to optical damage when exposed to high energy laser irradiation is not settled and several possible answers have been advanced in the literature.
Recently, in co-assigned, co-pending PCT patent application Ser. No. PCT/US97/11697, deposited Jul. 1, 1997, titled “Fused Silica Having High Resistance to Optical Damage,” it was suggested that radiation-caused optical damage can be minimized or eliminated by precompacting fused silica by such processes as hot isostatic pressing and by high energy pre-exposure in order to thereby desensitize the glass to subsequent high energy irradiation during actual use.
There continues to be a need for laser damage resistant fused silica. Accordingly, it is the object of the present invention to provide a fused silica stepper lens which is resistant to laser-induced damage, specifically defined as densification.
SUMMARY OF THE INVENTION
Briefly, the invention relates to a fused silica stepper lens which is resistant to laser-induced compaction. In particular, the invention relates to stepper lenses made by flame hydrolysis, and sol gel methods.


REFERENCES:
patent: 3933454 (1976-01-01), DeLuca
patent: 4789389 (1988-12-01), Schermerhorn et al.
patent: 5043002 (1991-08-01), Dobbins et al.
patent: 5086352 (1992-02-01), Yamagata et al.
patent: 5152819 (1992-10-01), Blackwell et al.
patent: 5154744 (1992-10-01), Blackwell et al.
patent: 5325230 (1994-06-01), Yamagata et al.
patent: 5364433 (1994-11-01), Nishimura et al.
patent: 5410428 (1995-04-01), Yamagata et al.
patent: 5523266 (1996-06-01), Nishimura et al.
patent: 5616159 (1997-04-01), Araujo et al.
patent: 5668067 (1997-09-01), Araujo et al.
patent: 5707908 (1998-01-01), Komine et al.
patent: 5735921 (1998-04-01), Araujo et al.
patent: 5896222 (1999-04-01), Rosplock et al.
patent: 5958809 (1999-09-01), Fujiwara et al.
patent: 6087283 (2000-07-01), Jinbo et al.
patent: 6205818 (2001-03-01), Seward, III
patent: 406016449A (1993-02-01), None
patent: 9300307A1 (1993-01-01), None
Allan et al., “193-nm excimer-laser-induced densification of fused silica”.Optics Letters, 21:24, Dec. 15, 1996, 1960-1962..
Borrelli et al., “Densification of fused silica under 193-nm excitation”,J. Opt. Soc. Am. B, 14:1606-1615, Jul. 1997.
EerNisse, E., “Compaction of ion-implanted fused silica,”J. Appl. Phys., 45:167-174 (1974). No month.
Imai, et al., “UV and VUV Optical Absorption Due to Intrinsic and Laser Induced Defects in Synthetic Silica Glasses” inThe Physics and Technology of Amorphous SiO2,edited by Roderick A. B. Devine, Plenum Press, New York, 153-159, (1988). No month.
Lillie et al., “Fine Annealing of Optical Glass”J. Am. Cer. Soc., 37:466-473, 1954. No month.
Moynihan, et al., “Dependence of the fictive temperature of glass on cooling rate,”J. Am. Cer. Soc. 59:12-16 (1976). No month.
Nagasawa et al., “Improvement of Radiation Resistance of Pure Silica Core Fibers by Hydrogen Treatment,”Japanese Journal of Applied Physics24:1224-1228 (1985). No month.
Norris et al., “Ionization dilatation effects in fused silica from 2 to 18-keV electron irradiation,”J. Appl. Phys. 45, 3876-3882 (1974). No month.
Primak et al., “The Radiation Compaction of Vitreous silica”,J. Appl. Phys. 39, 5651-5658 (1968). No month.
Primak, W., “Dependence of the compaction of vitreous silica on the ionization dose,”J. Appl. Phys. 49, 2572 (1977).
Primak, W., Section C, “Ionization Compaction,” in “The compacted States of Vitreous Silica,” vol. 4 ofStudies in Radiation Effects in Solids, edited by G.J. Dienes and L.T. Chadderton (Gordon and Breach, 1975), 91-102. No month.
Rothschild et al., “Effects of excimer laser irradiation on the transmission, index of refraction, and density of ultraviolet grade fused silica”,Appl. Phys. Lett. 55:1276-127 (1989). No month.
Ruller et al., “The effect of gamma-irradiation on the density of various types of silica”,Journal of Non-Crystalline Solids, 136:163-172, 1991. No month.
Schenker et al., “Degradation of fused silica at 193-nm and 213-nm,”SPIE, 2440:118-125, 1995. No month.
Schenker et al., “Ultraviolet damage properties of various fused silica materials,”SPIE, 2428:458-468 (1995). No month.
Schenker et al., “Material Limitations to 193-nm Lithographic System Lifetimes,”SPIE, 2726:698-707 (1996). No month.
Schermerhorn, P. “Excimer Laser Damage Testing of Optical Materials,”SPIE, 1835:70-79, 1992. No month.
Schroeder, “Brillouin Scattering and Pockels Coefficients in Silicate Glasses”,Journal of Non-Crystalline Solids, 40:549-566, 1980. No month.
Shelby, “Radiation effects in hydrogen-impregnated vitreous silica”,J. Appl. Phys., 50:3702-3706, 1979. No month.
Smith et al., “193-nm excimer laster induced processes of fused silica,” presented at 2ndInternational Symposium on 193-nm Lithography, Colorado Springs, CO, Jul. 30-Aug. 2, 1996.
Derwent Acc No.: 1993-03801, Fujinoki et ak, “Mfg. Silica Glass Article for Use with an Excimer Laser”, Feb. 1993.

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