Water immersion optical lithography at 193 nm

Smith, Bruce W.; Bourov, Anatoly; Kang, Houyang; Cropanese, Frank; Fan, Yongfa; Lafferty, Neal; Zavyalova, Lena

doi:10.1117/1.1637594

Cited by 16 publications

(8 citation statements)

References 4 publications

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“…Nevertheless, the narrowest nanoslit (10-nm wide) for the lens is presently still very difficult to fabricate in a 400-nm-thick gold film. On the other land, the immersion lenses can improve the resolution limit of the given operating wavelength by filling the object space with a high-index material, which are widely used in optical ultrahighresolution imaging and microscopy, high-throughput nanolithography, and high-density optical data storage, e.g., water immersion lithography [19], oil, and solid immersion microscopes [20,21].…”

Section: Introductionmentioning

confidence: 99%

Robustly Efficient Superfocusing of Immersion Plasmonic Lenses Based on Coupled Nanoslits

Zhu

Yuan

et al. 2016

Plasmonics

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We report plasmonic lenses consisting of coupled nanoslits immersed in a high-index medium to obtain the robustly efficient superfocusing. Based on the geometrical optics and the wavefront reconstruction theory, an array of nanoslits perforated in a gold film and a series of spacings between adjacent nanoslits are optimally designed to realize the desired phase modulation for light focusing. The numerical results verify the design of each plasmonic lens in excellent agreement. For the given total phase difference of 2π, the immersion plasmonic lenses with smaller lens aperture can have much better focusing p e r f o r m a n c e t h a n t h e n o n -i m m e r s i o n o n e . A superfocusing spot of λ/4.39 is achieved using an oil immersion plasmonic lens with an aperture size of 4.97λ, resulting in a resolution improvement of 68.9 % compared with the non-immersion lens. Moreover, such superfocusing performance can be still well kept when the structural parameters of the lens, e.g., nanoslit width and metal film thickness, are deviated from the original design, making the final implementation of the superfocusing lenses much easier.

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Section: Introductionmentioning

confidence: 99%

Robustly Efficient Superfocusing of Immersion Plasmonic Lenses Based on Coupled Nanoslits

Zhu

Yuan

et al. 2016

Plasmonics

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“…Therefore, in order to increase the depth of focus (DOF) at current 193 nm photolithography systems, there is a need to develop new immersion fluids that have a higher refractive index than water with acceptable transparency at 193 nm since water is known as the best fluid for 193 nm immersion systems so far. 4 The goals of the research reported here are the discovery of aqueous systems possessing an index of refraction substantially greater than that of water at 193 nm and acceptable transparency at 193 nm and compatibility with pertinent photoresist systems employed at 193 nm. 4 Our initial investigation was performed with aqueous surfactant system because there are some potential benefits we could achieve by using surfactant systems.…”

Section: Na = N Sin θmentioning

confidence: 99%

“…4 The goals of the research reported here are the discovery of aqueous systems possessing an index of refraction substantially greater than that of water at 193 nm and acceptable transparency at 193 nm and compatibility with pertinent photoresist systems employed at 193 nm. 4 Our initial investigation was performed with aqueous surfactant system because there are some potential benefits we could achieve by using surfactant systems. These are: (1) Surfactants can be used in aqueous system which has the highest index of refraction and optical property so far, (2) Resists for 193 nm are known to be compatible with the surfactant systems to be investigated, (3) Surfactant micelles can scavenge materials leached from the resist and keep them dispersed and prevent redeposit of materials and formation of defects on the resist, (4) The proposed systems have established photostability and good environmental characteristics, (5) The proposed systems will allow a wide variation of structural modifications employing inexpensive, commercially available materials.…”

Section: Na = N Sin θmentioning

confidence: 99%

“…However, the maximum solubility of CTAC is only ~ 450 mM compared to SDS (> 800 mM). In order to find a candidate anion which can increase the refractive index of aqueous CTAC solution significantly, several salts were tested: NaIO 4 , NaClO 4 These salts were selected because all these salts have a heavy anion, which has the potential to increase the RI significantly. However, most of these salts have a pure solubility in water and CTAC solutions.…”

Section: The Effect Of Cationic Surfactant Ctac On Refractive Indexmentioning

confidence: 99%

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Amplification of the index of refraction of aqueous immersion fluids by ionic surfactants

et al. 2005

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In order to find new immersion liquids to improve the resolution of 193 nm immersion photolithography, we have attempted to discover aqueous system possessing an index of refraction greater than that of water using aqueous surfactant systems. The index of refraction (RI) of both cationic and anionic surfactant systems were examined in the presence of wide range of inorganic salts, and parameters such as size of surfactants, concentrations, and temperature were varied. The refractive index (RI) was found to be increased in the presence of both anionic and cationic surfactants compared to those of water and also increased as a function of surfactant concentration. However the refractive index tends to increase much more strongly as a function of salt concentration. In our study, a maximum RI enhancement was observed from 6.5 M CdCl 2 in 8.2 mM aqueous SDS solution. The effect of micellar properties such as the critical micelle concentration (cmc) and degree of ionization were systematically studied for aqueous SDS system in the presence of CdCl 2 . The correlation on index of refraction between empirical data and theoretical prediction were performed using the concept of molar refraction. Wavelength dependence of RI from theoretical prediction based on empirical equation was examined for various concentration of CdCl 2 system and the results are reported in the paper.Subject terms: index of refraction, immersion photolithography, ionic surfactants, 193 nm, SDS, CTAC, CdCl 2 IntroductionRecently, optical lithography has been incrementally marching toward dimensions less than 45 nm. The wavelength has been reduced to 193-nm and 157-nm lithography using F 2 laser was studied tentatively for the next generation of lithography. We have been studying the mechanism of the photodegradation that leads to darkening of polymer pellicles during exposure to 157 nm radiations in order to design new soft pellicle systems that possess acceptable characteristics for 157 nm photolithography.

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“…2 Therefore, for current 193 nm photolithography systems, there is a need to develop new immersion fluids that have a higher refractive index than water n = 1.44. 3 In addition, candidates must have an acceptable transparency at 193 nm. Recently, second generation fluids with a refractive index of ~ 1.6 at 193 nm have been prepared, driven by the growing interest in this area.…”

Section: Introductionmentioning

confidence: 99%

Outlook for potential third-generation immersion fluids

et al. 2007

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In a search for alkane candidates for 193 nm immersion fluids, several alkanes and cycloalkanes were synthesized, purified and screened to ascertain their absorption at 193 nm, refractive index and temperature dispersion coefficient in the context of the actual application. In general, cycloalkanes, and more specifically polycycloalkanes, possess a higher refractive index than do linear alkanes. Decalin, cyclodecane, perhydrophenanthreme (PHP), perhydrofluorene (PHF) and perhydropyrene (PHPY) are examined as potential second and third generation immersion fluids. The use of perhydropyrene, which possesses a high refractive index of 1.7014 at 193 nm, may be limited as an immersion fluid because of high absorption at 193 nm. Mixtures of cycloalkanes can lead to a higher enhancement of the refractive index together with a decrease on the viscosity. Exhaustive purification of the fluids is a critical step in determining the real absorption of the different fluids at 193 nm. Two simple purification processes of these cycloalkanes were developed that led to low absorption fluids in the VUV region. The possibility of forming the oxygen complex in aerated fluids was reduced by purging samples with argon or nitrogen. This easy elimination of the oxygen complex shows the weak bonding nature of this complex.

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Water immersion optical lithography at 193 nm

Cited by 16 publications

References 4 publications

Robustly Efficient Superfocusing of Immersion Plasmonic Lenses Based on Coupled Nanoslits

Robustly Efficient Superfocusing of Immersion Plasmonic Lenses Based on Coupled Nanoslits

Amplification of the index of refraction of aqueous immersion fluids by ionic surfactants

Outlook for potential third-generation immersion fluids

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