Conventional and Un-Conventional Lithography for Fabricating Thin Film Functional Devices

Thin film devices are conquering many aspects of today’s life, and continuous shrinking of building block dimensions of these structures enhances their performances and makes them economically attractive. This chapter is an overview of some conventional and unconventional lithography techniques used to fabricate thin film functional structures. Several aspects of pattern transfer were addressed with emphasis on the limits of these lithography techniques. We have thus highlighted the issue of pitch resolution for optical lithography and discussed some aspect of proximity effects for electron beam lithography. Pattern transfer from resist image to the wafer was also discussed. Considered as unconventional, we discussed several aspects linked to thin film fabrication using nanoimprint and nanosphere lithography techniques

Path-creating networks in the field of next generation lithography: outline of a research project

Der Beitrag stellt ein Forschungsprojekt vor, das die möglichen technologischen Pfade bei der Entwicklung von Halbleitern untersucht, die schließlich zu einer Produktion, also zu einer Umsetzung des technologischen Fortschritts, führen. An solch einem Vorgang sind Personen mit unterschiedlichem wissenschaftlichem Hintergrund (optische Physik, Elektrotechnik, Chemie) und verschiedene Gesellschaftsbereiche (Wissenschaft, Wirtschaft, Staat) beteiligt. In diesem Zusammenhang stellt sich nun die Ausgangsfrage des Projektes, in welchem Umfang, unter welchen Bedingungen und Organisations-Netzwerken die Kreation eines neuen technologischen Pfades möglich ist. In das Thema einführend, wird zunächst der Forschungsstand zum Zusammenhang zwischen der Theorie der Pfadabhängigkeit und dem Konzept der Pfadkreation im Prozess der Technologieentwicklung beschrieben. Auf dieser Grundlage folgt die Konzeptionalisierung des dargestellten Forschungsprojektes. Im Anschluss wird das empirische Untersuchungsfeld in seinen Grundzügen präsentiert: die Entwicklung einer neuen Lithographie-Generation für Halbleiter mit besonderer Berücksichtigung der unterschiedlichen technologischen Pfade, die als realisierbar anzusehen sind. So gilt es, bei der Betrachtung der Pfadkreation von technologischen Neuerungen die Entwicklung reflexiver interorganisationaler Netzwerke zu betrachten. Gemäß der spezifischen Forschungsfragen werden abschließend das Forschungsdesign und die methodologische Vorgehensweise präsentiert. So ist das Projekt auf den Zeitraum von 2004 bis 2009 zugeschnitten und umfasst drei Interviewphasen. Auf diese Weise kann der Innovationsprozess der nächsten Lithographie-Generation in Realzeit bis zur voraussichtlichen Produktion dieser neuen Systemtechnologie untersucht werden. (ICG2

a methodology for understanding path dependence and path creation

Although an increasing number of studies of technological, institutional and organizational change refer to the concepts of path dependence and path creation, few attempts have been made to consider these concepts explicitly in their methodological accounts. This paper addresses this gap and contributes to the literature by developing a comprehensive methodology that originates from the concepts of path dependence and path creation – path constitution analysis (PCA) – and allows for the integration of multi-actor constellations on multiple levels of analysis within a process perspective. Based upon a longitudinal case study in the field of semiconductors, we illustrate PCA ‘in action’ as a template for other researchers and critically examine its adequacy. We conclude with implications for further path-oriented inquiries

Surface Percolation and Growth. An alternative scheme for breaking the diffraction limit in optical patterning

A nanopatterning scheme is presented by which the structure height can be controlled in the tens of nanometers range and the lateral resolution is a factor at least three times better than the point spread function of the writing beam. The method relies on the initiation of the polymerization mediated by a very inefficient energy transfer from a fluorescent dye molecule after single photon absorption. The mechanism has the following distinctive steps: the dye adsorbs on the substrate surface with a higher concentration than in the bulk, upon illumination it triggers the polymerization, then isolated islands develop and merge into a uniform structure (percolation), which subsequently grows until the illumination is interrupted. This percolation mechanism has a threshold that introduces the needed nonlinearity for the fabrication of structures beyond the diffraction limit.Comment: 10 pages, 8 figure

CHEMICALLY AMPLIFIED RESISTS FOR ELECTRON BEAM LITHOGRAPHY

This thesis describes the development of chemically amplified resists for electron beam lithography. The techniques and concepts oflithography are discussed and the motivations for the development of chemically amplified resists are examined. The experimental techniques used in this work are then described. Two groups of resists, derivatives of fullerene and derivatives of triphenylene, were tested for chemical amplification and the results obtained from the research are presented. A systematic study of the response of several methanofullerenes and polysubstituted triphenylene derivatives before and after chemical amplification is presented. Films of the compounds were prepared by dissolving the resists in solvents such as chloroform and adding to the solution various concentrations of certain photoacid generators and crosslinkers, and spin coating the mixture on hydrogen terminated silicon wafers. The films were irradiated using 20 keY electrons. Post exposure bakes between 90 to 120 'C for 30 to 180 s were applied to the resists before development with non-polar solvents such as monochlorobenzene. Most of the chemically amplified resists showed sensitivity enhancement compared to their pure counterparts. Fullerene derivative, 3' H-cyclopropa [I, 9, 5, 6] fullerene-C60-Ih - 3', 3'- carboxylic [ 2-2-(2-hydroxyethoxy) ethoxyl ethyl] ester (a mixture of adducts) demonstrated the highest sensitivity enhancement with the incorporation of an epoxy novolac crosslinker and bis[4-di(phenylsulfonio) phenyl]sulfide bis(hexafluorophoshate) as photoacid generator with a sensitivity of -8 ~Clem' and a resolution of -24 nm. The polysubstituted triphenylene derivative, 2,6,10-trihydroxy-3,7,11- tri(pentyloxy) triphenylene, showed a sensitivity of -5 ~Clem' when the crosslinker hexamethoxymethylmelamine and the photoacid generator triphenylsulfonium triflate were added to the compound. However, fine patterning in the resist was not very successful due to acid diffusion. An alternative triphenylene derivative similar to 2,6, 1 0-trihydroxy-3,7, 11- tri(pentyloxy) triphenylene, with epoxides incorporated into the structure showed better results with the photoinitiator bis[ 4-di(pheny lsulfonio) phenyl]sulfide bis(hexa fluorophoshate). The chemically amplified C51epoxide demonstrated a sensitivity of ~9 f..!C/cm2 and a resolution of 40 nm. The etch durabilities of these chemically amplified resists for dry plasma etching with SF6 are reasonably high, comparable to a conventional high durability novolac resist

Electrostatic Deflection and Correction Systems

Tato diplomová práce se věnuje prozkoumání možností dynamické korekce vad v elektronové litografii. Pro výpočty byl zvolen elektronový litograf BS600. Práce se zabývá korekcí vad vychýlení třetího řádu: zklenutí pole, astigmatismu a zkreslení. Aberace byly spočteny jak pro současný magnetický vychyolvací systém, tak pro nově navržený elektrostatický deflektor. Vlastnosti a vady obou vychylovacích a korekčních systémů byly porovnány.The aim of this master's thesis is to explore and study dynamic aberration correction options in electron-beam lithography systems. For the calculations, the thesis uses the optical column of the BS600 electron-beam writer. The thesis focuses on corrections of the third order field curvature, astigmatism, and distortion aberrations of the currently used magnetic deflection system and a newly designed electrostatic deflection system. The parameters of the two deflection and correction systems were compared.

Resolution Improvement and Pattern Generator Development for theMaskless Micro-Ion-Beam Reduction Lithography System

The shrinking of IC devices has followed the Moore's Law for over three decades, which states that the density of transistors on integrated circuits will double about every two years. This great achievement is obtained via continuous advance in lithography technology. With the adoption of complicated resolution enhancement technologies, such as the phase shifting mask (PSM), the optical proximity correction (OPC), optical lithography with wavelength of 193 nm has enabled 45 nm printing by immersion method. However, this achievement comes together with the skyrocketing cost of masks, which makes the production of low volume application-specific IC (ASIC) impractical. In order to provide an economical lithography approach for low to medium volume advanced IC fabrication, a maskless ion beam lithography method, called Maskless Micro-ion-beam Reduction Lithography (MMRL), has been developed in the Lawrence Berkeley National Laboratory. The development of the prototype MMRL system has been described by Dr. Vinh Van Ngo in his Ph.D. thesis. But the resolution realized on the prototype MMRL system was far from the design expectation. In order to improve the resolution of the MMRL system, the ion optical system has been investigated. By integrating a field-free limiting aperture into the optical column, reducing the electromagnetic interference and cleaning the RF plasma, the resolution has been improved to around 50 nm. Computational analysis indicates that the MMRL system can be operated with an exposure field size of 0.25 mm and a beam half angle of 1.0 mrad on the wafer plane. Ion-ion interactions have been studied with a two-particle physics model. The results are in excellent agreement with those published by the other research groups. The charge-interaction analysis of MMRL shows that the ion-ion interactions must be reduced in order to obtain a throughput higher than 10 wafers per hour on 300-mm wafers. In addition, two different maskless lithography strategies have been studied. The dependence of the throughput with the exposure field size and the speed of the mechanical stage has been investigated. In order to perform maskless lithography, different micro-fabricated pattern generators have been developed for the MMRL system. Ion beamlet switching has been successfully demonstrated on the MMRL system. A positive bias voltage around 10 volts is sufficient to switch off the ion current on the micro-fabricated pattern generators. Some unexpected problems, such as the high-energy secondary electron radiations, have been discovered during the experimental investigation. Thermal and structural analysis indicates that the aperture displacement error induced by thermal expansion can satisfy the 3{delta} CD requirement for lithography nodes down to 25 nm. The cross-talking effect near the surface and inside the apertures of the pattern generator has been simulated in a 3-D ray-tracing code. New pattern generator design has been proposed to reduce the cross-talking effect. In order to eliminate the surface charging effect caused by the secondary electrons, a new beam-switching scheme in which the switching electrodes are immersed in the plasma has been demonstrated on a mechanically fabricated pattern generator

Scanning evanescent wave lithography for sub-22nm generations

Current assumptions for the limits of immersion optical lithography include NA values at 1.35, largely based on the lack of high-index materials. In this research we have been working with ultra-high NA evanescent wave lithography (EWL) where the NA of the projection system is allowed to exceed the corresponding acceptance angle of one or more materials of the system. This approach is made possible by frustrating the total internal reflection (TIR) evanescent field into propagation. With photoresist as the frustrating media, the allowable gap for adequate exposure latitude is in the sub-100 nm range. Through static imaging, we have demonstrated the ability to resolve 26 nm half-pitch features at 193 nm and 1.85 NA using existing materials. Such imaging could lead to the attainment of 13 nm half-pitch through double patterning. In addition, a scanning EWL imaging system was designed, prototyped with a two-stage gap control imaging head including a DC noise canceling carrying air-bearing, and a AC noise canceling piezoelectric transducer with real-time closed-loop feedback from gap detection. Various design aspects of the system including gap detection, feedback actuation, prism design and fabrication, software integration, and scanning scheme have been carefully considered to ensure sub-100 nm scanning. Experiments performed showed successful gap gauging at sub-100 nm scanning height. Scanning EWL results using a two-beam interference imaging approach achieved pattern resolution comparable to static EWL imaging results. With this scanning EWL approach and the imaging head developed, optical lithography becomes extendable to sub-22 nm generations