L-Shape based Layout Fracturing for E-Beam Lithography

Layout fracturing is a fundamental step in mask data preparation and e-beam lithography (EBL) writing. To increase EBL throughput, recently a new L-shape writing strategy is proposed, which calls for new L-shape fracturing, versus the conventional rectangular fracturing. Meanwhile, during layout fracturing, one must minimize very small/narrow features, also called slivers, due to manufacturability concern. This paper addresses this new research problem of how to perform L-shaped fracturing with sliver minimization. We propose two novel algorithms. The first one, rectangular merging (RM), starts from a set of rectangular fractures and merges them optimally to form L-shape fracturing. The second algorithm, direct L-shape fracturing (DLF), directly and effectively fractures the input layouts into L-shapes with sliver minimization. The experimental results show that our algorithms are very effective

E-BLOW: E-Beam Lithography Overlapping aware Stencil Planning for MCC System

Electron beam lithography (EBL) is a promising maskless solution for the technology beyond 14nm logic node. To overcome its throughput limitation, recently the traditional EBL system is extended into MCC system. %to further improve the throughput. In this paper, we present E-BLOW, a tool to solve the overlapping aware stencil planning (OSP) problems in MCC system. E-BLOW is integrated with several novel speedup techniques, i.e., successive relaxation, dynamic programming and KD-Tree based clustering, to achieve a good performance in terms of runtime and solution quality. Experimental results show that, compared with previous works, E-BLOW demonstrates better performance for both conventional EBL system and MCC system

Nanoscale Fabrication by Intrinsic Suppression of Proximity-Electron Exposures and General Considerations for Easy & Effective Top-Down Fabrication

We present results of a planar process development based on the combination of electron-beam lithography and dry etching for fabricating high-quality superconducting photosensitive structures in the sub-100nm regime. The devices were fabricated by the application of an intrinsic proximity effect suppression procedure which makes the need for an elaborated correction algorithm redundant for planar design layouts which are orders of magnitude smaller than the backscattering length. In addition, we discuss the necessary considerations for extending the fabrication spatial scale of optical contactlithography with a mercury arc-discharge photon source down to the order of the exposure photon's wavelength ( sub-{\mu}m ), thereby minimizing the writing time on the electron-beam lithograph. Finally we developed a unique and novel technique for controlling the undercut during a planar lift-off fabrication procedure without cleaving the wafer.Comment: 10 figures, 51 reference

Improvements to the alignment process in electron-beam lithography

Electron beam lithography is capable of defining structures with sub-10 nm linewidths. To exploit this capability to produce working devices with structures defined in multiple 'lithographic steps' a process of alignment must be used. The conventional method of scanning the electron beam across simple geometrically shaped markers will be shown inherently to limit the alignment accuracy attainable. Improvements to alignment allow precise placement of elements in complex multi-level devices and may be used to realise structures which are significantly smaller than the single exposure resist limit. Correlation based alignment has been used previously as an alignment technique, providing improvements to the attainable accuracy and noise immunity of alignment. It is well known that the marker pattern used in correlation based alignment has a strong influence on the magnitude of the improvements that can be realised. There has, to date, however, been no analytical study of how the design of marker pattern affects the correlation process and hence the alignment accuracy possible. This thesis analyses the correlation process to identify the features of marker patterns that are advantageous for correlation based alignment. Several classes of patterns have been investigated, with a range of metrics used to determine the suitability and performance of each type of pattern. Penrose tilings were selected on this basis as the most appropriate pattern type for use as markers in correlation based alignment. A process for performing correlation based alignment has been implemented on a commercial electron beam lithography tool and the improvements to the alignment accuracy have been demonstrated. A method of measuring alignment accuracy at the nanometer scale, based on the Fourier analysis of inter-digitated grating has been introduced. The improvements in alignment accuracy realised have been used to facilitate the fabrication of 'nanogap' and 'nanowire' devices - structures which have application in the fields of molecular electronics and quantum conduction. Fabrication procedures for such devices are demonstrated and electrical measurements of such structures presented to show that it is a feasible method of fabrication which offers much greater flexibility than the existing methods for creating these devices

Resonant Waveguide Gratings for Color-Selective Diffraction

Resonant waveguide gratings (RWGs), also known as guided mode resonant (GMR) gratings or waveguide-mode resonant gratings, are dielectric structures where these resonant diffractive elements benefit from lateral leaky guided modes and can operate from UV to microwave frequencies, in many different configurations. Some of the guided light is diffracted out of the guide while propagating, coupled back to radiation and interferes with the non-coupled reflected or transmitted waves. This leads to a very high reflection or transmission, giving rise to a Fano or Lorentzian-like lineshape profile at the zeroth order. RWGs are intrinsically very sensitive to angle and wavelength variations, being therefore effective filtering structures, especially for collimated light. Thanks to their high degree of optical tunability (wavelength, phase, polarization, intensity) and the variety of fabrication processes and materials available, RWGs have been implemented in a broad scope of applications in research and industry, such as optical security features, refractive index and fluorescence biosensors, spectrometers and optical couplers. This thesis describes the development and realization of color-selective diffraction devices using RWGs. The properties of paired impedance matched RWGs with finite size and different grating periods, but sharing the same substrate and coated waveguide, are first investigated. In particular, a specific wavelength range is in-coupled inside the waveguide by the first grating from a white incident light beam, and out-coupled from the second grating at a different angle. Periodic arrays of such paired RWGs allow achieving color-selective diffraction. Moreover, specific design methods based on confocal prolate spheroids are derived and used to generate surfaces with different grating periods and orientations, which can filter a specific spectral portion of a point source and to redirect and focus it to another point in space, viz. the observation point. This patterning is particularly beneficial in applications where light re-focusing is required, such as optical security or optical combiners for near-eye displays. Realizations as optical security labels through smartphone-based authentication are presented and discussed. Since the fabrication of such devices is extremely demanding, a fabrication method is developed to reduce the exposure time for the electron beam lithography. This method is beneficial to efficiently fabricate gratings with different periods and oriented at different angles. In particular, a pre-fracturing of the grating lines in one or more smaller stripes, depending on the grating period, is first implemented, followed by the fracturing using a beam step size smaller than the beam diameter. In the last part, optical structures comprising a metallic layer and a dielectric layer on a corrugated glass substrate are described. In essence, the hybridization of plasmon and waveguide modes is studied and used to design a color-selective optical coupler where the hybridized modes are leaking into the substrate at the first diffraction order and are coupled as guided mode. Such coupler may be used as dispersive element when the white light source is divergent allowing, for example, the realization of inexpensive, compact and robust spectrometers

The Nanolithography Toolbox

This article introduces in archival form the Nanolithography Toolbox, a platform-independent software package for scripted lithography pattern layout generation. The Center for Nanoscale Science and Technology (CNST) at the National Institute of Standards and Technology (NIST) developed the Nanolithography Toolbox to help users of the CNST NanoFab design devices with complex curves and aggressive critical dimensions. Using parameterized shapes as building blocks, the Nanolithography Toolbox allows users to rapidly design and layout nanoscale devices of arbitrary complexity through scripting and programming. The Toolbox offers many parameterized shapes, including structure libraries for micro- and nanoelectromechanical systems (MEMS and NEMS) and nanophotonic devices. Furthermore, the Toolbox allows users to precisely define the number of vertices for each shape or create vectorized shapes using Bezier curves. Parameterized control allows users to design smooth curves with complex shapes. The Toolbox is applicable to a broad range of design tasks in the fabrication of microscale and nanoscale devices

Design of LCOS microdisplay backplanes for projection applications

De evolutie van licht emitterende diodes (LED) heeft ervoor gezorgd dat het op dit moment interessant wordt om deze componenten als lichtbron te gebruiken in projectiesystemen. LED’s hebben belangrijke voordelen vergeleken met klassieke booglampen. Ze zijn compact, ze hebben een veel grotere levensduur en ogenblikkelijke schakeltijden, ze werken op lage spanningen, etc. LED’s zijn smalbandig en kunnen een groterekleurenbereik realiseren. Ze hebben momenteel echter een beperkte helderheid. Naast de lichtbron is het type van de lichtklep ook bepalend voor de kwaliteit van een projectiesysteem. Er bestaan verschillende lichtkleptechnologieën waaronder die van de reflectieve LCOS-panelen. Deze lichtkleppen kunnen zeer hoge resoluties hebben en wordenvaak gebruikt in kwalitatieve, professionele projectiesystemen. LED’s zijn echter totaal verschillend van booglampen. Ze hebben een andere vorm, package, stralingspatroon, aansturing, fysische en thermische eigenschappen, etc. Hoewel er een twintigtal optische architecturen bekend zijn voor reflectieve beeldschermen (met een booglamp als lichtbron), zijn ze niet geschikt voor LED-projectoren en moeten nieuwe optische architecturen en een elektronische aansturing ontwikkeld worden. In dit doctoraat werd er hieromtrent onderzoek gedaan. Er werd uiteindelijk een driekleurenprojector (R, G, B) met een efficiënt LED-belichtingssysteem gebouwd met twee LCOS-lichtkleppen. Deze LEDprojector heeft superieure eigenschappen (zeer lange levensduur, beeldkwaliteit, etc.) en een matige lichtopbrengst