Near-field photolithography with a solid immersion lens

Ghislain, Lucien P.; Elings, Virgil B.; Crozier, Kenneth B.; Manalis, Scott R.; Minne, S. C.; Wilder, Kathryn; Kino, G. S.; Quate, C. F.

doi:10.1063/1.123168

Cited by 146 publications

(65 citation statements)

References 15 publications

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“…A SIL probe with a spot size of approximately 100 nm transmits about 50% of the optical power [25,28,38]. By comparison, a metal-coated fiberprobe with a 100 nm aperture transmits only a fraction (10 -3 -10 -6 ) of the light coupled into the fiber [16,[39][40][41].…”

Section: Discussionmentioning

confidence: 99%

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Extension of solid immersion lens technology to super-resolution Raman microscopy

Ostertag¹,

Lorenz²,

Rebner³

et al. 2014

Nanospectroscopy

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The near-field accessed with solid immersion lens technologyThe main reason for using solid immersion lenses is their capability to enhance the spatial resolution. Solids have higher refractive indices than air. When used as the immersion medium, light travels more slowly and the wavelength is shorter in the optically denser medium which results in an improvement in resolution. Mansfield and Kino were the first to recommend the SIL for increasing the spatial resolution of the optical microscope [1]. A SIL is a spherical lens (diameter 2r, refractive index n SIL ) which is polished to a thickness of r (hemisphere type) or (1+1/n SIL )r (supersphere or Weierstrass type) [2,3]. The sphere diameter is usually in the range of single millimeters down to micrometers. The numerical aperture (NA) of the complete system is improved by factor of n SIL (hemisphere type) or (n SIL ) 2 (Weierstrass type) -subject to the condition that the refractive index of the substrate is at least as high as the refractive index of the SIL. If this condition is not met, the refractive index of the substrate limits the effective numerical aperture NA eff of the SIL/ objective optical system (with NA eff = n SIL sinα m , where α m is the marginal ray angle inside the SIL) [4]. The angular range of collected information is determined by the SIL probe, the objective lens, and the detector [5].The SIL technique is also known as "numerical aperture increasing lens (NAIL) microscopy" [6]. For the NAIL technique the inclusion of evanescent waves is crucial for resolution gain [7]. Tom Milster et al. have described the role of propagating and evanescent waves in solid immersion lens systems [8].It must be emphasized here that the lateral resolution of a SIL microscope can exceed the "NAIL Limit", i.e. by the factor of the refractive index n SIL . In order to achieve this, the evanescent component of the light from the substrate has to be identified amongst the predominant propagated component. One approach is to tailor the angular spectrum by annular illumination and collection which can significantly improve the resolution and emphasize Abstract: Scanning Near-Field Optical Microscopy (SNOM) has developed during recent decades into a valuable tool to optically image the surface topology of materials with super-resolution. With aperture-based SNOM systems, the resolution scales with the size of the aperture, but also limits the sensitivity of the detection and thus the application for spectroscopic techniques like Raman SNOM. In this paper we report the extension of solid immersion lens (SIL) technology to Raman SNOM. The hemispherical SIL with a tip on the bottom acts as an apertureless dielectric nanoprobe for simultaneously acquiring topographic and spectroscopic information. The SIL is placed between the sample and the microscope objective of a confocal Raman microscope. The lateral resolution in the Raman mode is validated with a cross section of a semiconductor layer system and, at approximately 180 nm, is beyond the classical diffraction lim...

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Section: Discussionmentioning

confidence: 99%

“…Further applications include high-resolution imaging [24][25][26][27], lithography [28,29] and spectroscopy [24,30].…”

Section: The Near-field Accessed With Solid Immersion Lens Technologymentioning

confidence: 99%

Extension of solid immersion lens technology to super-resolution Raman microscopy

Ostertag¹,

Lorenz²,

Rebner³

et al. 2014

Nanospectroscopy

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“…Since its invention, the SIL has been exploited in several nanoscale technologies, including semiconductor integrated-circuit (IC) inspection [1][2][3], nanoscale spectroscopy [4,5], optical data storage [6,7] and photolithography [8], yet the benefits the SIL has introduced in these fields have received poor coverage. Therefore, in this paper we aim to review the theoretical aspects of the SIL and to discuss recent demonstrations of SIL-enhanced technologies in nanophotonics.…”

Section: Introductionmentioning

confidence: 99%

Solid immersion lens applications for nanophotonic devices

Ramsay¹

2008

J. Nanophoton

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Abstract. Solid immersion lens (SIL) microscopy combines the advantages of conventional microscopy with those of near-field techniques, and is being increasingly adopted across a diverse range of technologies and applications. A comprehensive overview of the state-of-the-art in this rapidly expanding subject is therefore increasingly relevant. Important benefits are enabled by SIL-focusing, including an improved lateral and axial spatial profiling resolution when a SIL is used in laser-scanning microscopy or excitation, and an improved collection efficiency when a SIL is used in a light-collection mode, for example in fluorescence micro-spectroscopy. These advantages arise from the increase in numerical aperture (NA) that is provided by a SIL. Other SIL-enhanced improvements, for example spherical-aberration-free sub-surface imaging, are a fundamental consequence of the aplanatic imaging condition that results from the spherical geometry of the SIL. The theory of SIL imaging exposes the unique properties of SILs that provide advantages in applications involving the interrogation of photonic and electronic nanostructures. Such applications range from the sub-surface examination of the complex three-dimensional microstructures fabricated in silicon integrated circuits, to quantum photoluminescence and transmission measurements in semiconductor quantum dot nanostructures.

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“…The enhancement of the peak intensity provides an additional confirmation of the immersion effect in the nano-SIL. Prospective applications of such nano-SILs include near-field focusing and imaging [11], optical data storage [19], and maskless direct-write lithography [20]. Furthermore, the introduction of plasmonic structures on the bottom of the SIL could further improve performance and resolution [21].…”

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confidence: 99%

Subwavelength-size solid immersion lens

et al. 2011

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We report on the fabrication and characterization of nanoscale solid immersion lenses (nano-SILs) with sizes down to a subwavelength range. Submicrometer-scale cylinders fabricated by electron-beam lithography are thermally reflowed to form a spherical shape. Subsequent soft lithography leads to nano-SILs on transparent substrates for optical characterization. The optical characterization is performed using a high-resolution interference microscope with illumination at 642 nm wavelength. The focal spots produced by the nano-SILs show both spot-size reduction and enhanced optical intensity, which are consistent with the immersion effect. © 2011 Optical Society of America OCIS codes: 220.4241, 310.6628, 180.3170. Hooke first discussed the immersion technique to improve the imaging performance of a microscope in 1678 [1]. Although the concept of homogeneous immersion preceded Abbe's pioneering work, he constructed the first oil-immersion lens in developing the imaging theory of microscopy [2]. Abbe also developed the standard measure of performance of an objective lens, the numerical aperture (NA), which is defined as [3]where θ is the angle a ray makes with the optical axis (half the angle of the focusing cone), and n is the refractive index of the medium through which the rays pass. In 1990, Mansfield et al. developed a new immersion concept, which is termed solid immersion lens (SIL) [4]. Focusing in the center of a hemispherical solid leads to normal incidence of the rays with respect to the spherical interface. Therefore, there is no refraction at the interface between the spherical solid and the surrounding medium (e.g., air), leading to an increase in the NA by a factor of n (the refractive index of the solid medium) as shown in Eq. (1). At the beginning, the fabrication of SILs was limited to macroscopic size (i.e., millimeter scale). Advances in micro-and nanofabrication technologies enabled the development of different types of SILs, including diffractive SILs [5], micrometer-size SILs [6-9], nanoscale spherical lenses [10], and wavelength-scale SILs [11].The goal of this Letter is to report on the fabrication and optical characterization of nanoscale SILs (nanoSILs) with sizes down to subwavelength range. In general, for structures smaller than the optical wavelength, design methods for larger devices, such as ray optics, are not applicable. More specifically, subwavelength-scale lenses cannot simply be considered to be refractive optical surfaces. However, recent modeling work has shown that subwavelength-scale SILs are still expected to produce a reduced size focal spot [11], the so-called immersion effect. To the best of our knowledge, in this Letter we report the first experimental demonstration of the immersion effect in subwavelength-scale nano-SILs.Electron-beam lithography (EBL) was used to form cylindrical nanostructures with two dimensions: (1) 600 nm diameter and 200 nm height; and (2) 450 nm diameter and 150 nm height, which are shown in the scanning electron microscope (SEM) images of Fi...

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Near-field photolithography with a solid immersion lens

Cited by 146 publications

References 15 publications

Extension of solid immersion lens technology to super-resolution Raman microscopy

Extension of solid immersion lens technology to super-resolution Raman microscopy

Solid immersion lens applications for nanophotonic devices

Subwavelength-size solid immersion lens

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