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Browsing by Author "Marconi, Mario C., advisor"

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    Applications of extreme ultraviolet compact lasers to nanopatterning and high resolution holographic imaging
    (Colorado State University. Libraries, 2008) Wachulak, Przemyslaw Wojciech, author; Marconi, Mario C., advisor
    This dissertation describes two applications of extreme ultraviolet light in nanotechnology. Using radiation with a wavelength in the extreme ultraviolet (EUV) range allows to reach scales much smaller than with a conventional visible illumination. The first part of this dissertation describes a series of experiments that allowed the patterning at nanometer scales with sub-100nm resolution. Two types of photoresists (positive tone - PMMA and negative tone - HSQ) were patterned over the areas up to a few mm2 with features as small as 45nm using the interferometric lithography approach, reaching resolution equivalent to the wavelength of the illumination - 46.9nm. For the nanopatterning experiments two types of interferometers were studied in detail: Lloyd's mirror configuration and an amplitude division interferometer. Both approaches are presented and their advantages and drawbacks are discussed. The second part of the dissertation focuses on holographic imaging with ultimate resolution approaching the wavelength of the illumination. Different experiments were performed using Gabor's in-line holographic configuration and its capabilities in the EUV region were discussed. Holographic imaging was performed with different objects: AFM probes, spherical markers and carbon nanotubes. The holograms were stored in a high resolution recording medium - photoresist, digitized with an atomic force microscope and numerically reconstructed using a code based on the Fresnel propagator algorithm achieving in the reconstructed images the ultimate wavelength resolution. The resolution for the carbon nano-tubes images was assessed by two independent measurements: the knife-edge test resulting 45.5nm and an algorithm based on the correlation between the reconstructed image and a set of templates with variable resolution obtained by successive Gaussian filtering. This analysis yielded a resolution ~46nm. A similar algorithm that allowed for the simultaneous assessment of the resolution and the size of the features was used in EUV microscopy images confirming the validity and robustness of the code. A very fast, non-recursive reconstruction algorithm based on fast Fourier transform allowed for three dimensional surface reconstruction of the hologram performed by optical numerical sectioning, with a lateral resolution ~200nm and depth resolution ~2μm.
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    Coherent EUV lithography with table-top laser
    (Colorado State University. Libraries, 2012) Urbanski, Lukasz, author; Marconi, Mario C., advisor; Bartels, Randy A., committee member; Menoni, Carmen S., committee member; Putkaradze, Vakhtang, committee member
    This dissertation describes alternative techniques of optical lithography in the extreme ultraviolet (EUV) region of the electromagnetic spectrum. The pursuit of the Moore's law forces the semiconductor industry to transfer to shorter wavelengths of illumination in projection lithography. The EUV light is perhaps the most viable candidate for the next generation integrated circuits printing. However, the EUV lithography encounters many challenges associated with the very nature of the light it is using. Many novel techniques and materials are being applied at the same time in the lithography process. As such the process itself is far from being reliable. Thus the solutions are being sought among the alternative methods of printing in the nano-scale that would aid to temporarily overpass the resolution gap. This thesis contains a description of several alternative techniques of nanofabrication with the EUV light. For each method the analytical description is provided that is further corroborated with numerical model simulations. Furthermore every technique presented here is verified experimentally. The proposed techniques are discussed in terms of their applicability as a self consistent nanofabrication process. The illumination source for all the techniques presented is the capillary discharge laser (CDL) that was engineered at Colorado State University; it is characterized in the chapter 2 of this dissertation. The CDL is an unbeatable table-top source of high average power illumination with the degree of coherence that is sufficient for coherent nano-scale printing. A separate chapter is dedicated to the description of the fabrication protocol of a diffractive optical element (the mask) used in the EUV nanopatterning techniques. This particular chapter is intended to serve as a potential reference manual for the EUV masks fabrication. The coherent EUV nanofabrication techniques described in the chapters 4-6 are: the holographic projection lithography, generalized Talbot imaging (GTI), and de-magnified generalized Talbot imaging. A separate chapter is devoted to the defect tolerance property of the GTI technique.
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    Periodic metallic nanostructures fabricated by coherent Talbot lithography in a table top system
    (Colorado State University. Libraries, 2013) Li, Wei, author; Marconi, Mario C., advisor; Menoni, Carmen S., committee member; Wu, Mingzhong, committee member
    This thesis describes a novel technique of extreme ultraviolet (EUV) lithography. A compact nanofabrication system that combines Talbot lithography and a table top extreme ultraviolet laser illumination is presented. The lithographic method based on the Talbot effect provides a robust and simple experimental setup that is capable to print arbitrary periodic structures over millimeter square areas free of defects. Test structures were printed and metalized by ion beam etching system which was rebuilt and calibrated as part of this work. The results demonstrate that a complete coherent extreme ultraviolet lithographic process based on a table top system has the capability to fabricate functional periodic metallic nanostructures. Preliminary results and prospects for future work are also presented at the end of this thesis.
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    Progress in coherent lithography using table-top extreme ultraviolet lasers
    (Colorado State University. Libraries, 2016) Li, Wei, author; Marconi, Mario C., advisor; Menoni, Carmen S., advisor; Wu, Mingzhong, committee member; Krapf, Diego, committee member
    Nanotechnology has drawn a wide variety of attention as interesting phenomena occurs when the dimension of the structures is in the nanometer scale. The particular characteristics of nanoscale structures had enabled new applications in different fields in science and technology. Our capability to fabricate these nanostructures routinely for sure will impact the advancement of nanoscience. Apart from the high volume manufacturing in semiconductor industry, a small-scale but reliable nanofabrication tool can dramatically help the research in the field of nanotechnology. This dissertation describes alternative extreme ultraviolet (EUV) lithography techniques which combine table-top EUV laser and various cost-effective imaging strategies. For each technique, numerical simulations, system design, experiment result and its analysis will be presented. In chapter II, a brief review of the main characteristics of table-top EUV lasers will be addressed concentrating on its high power and large coherence radius that enable the lithography application described herein. The development of a Talbot EUV lithography system which is capable of printing 50nm half pitch nanopatterns will be illustrated in chapter III. A detailed discussion of its resolution limit will be presented followed by the development of X-Y-Z positioning stage, the fabrication protocol for diffractive EUV mask, and the pattern transfer using self- developed ion beam etching, and the dose control unit. In addition, this dissertation demonstrated the capability to fabricate functional periodic nanostructures using Talbot EUV lithography. After that, resolution enhancement techniques like multiple exposure, displacement Talbot EUV lithography, fractional Talbot EUV lithography, and Talbot lithography using 18.9nm amplified spontaneous emission laser will be demonstrated. Chapter IV will describe a hybrid EUV lithography which combines the Talbot imaging and interference lithography rendering a high resolution interference pattern whose lattice is modified by a custom designed Talbot mask. In other words, this method enables filling the arbitrary Talbot cell with ultra-fine interference nanofeatures. Detailed optics modeling, system design and experiment results using He-Ne laser and table top EUV laser are included. The last part of chapter IV will analyze its exclusive advantages over traditional Talbot or interference lithography.