ICMCTF2004 Session C3: Engineered Photonic Thin Films and Structures

Tuesday, April 20, 2004 1:30 PM in Room Sunset

Tuesday Afternoon

Time Period TuA Sessions | Abstract Timeline | Topic C Sessions | Time Periods | Topics | ICMCTF2004 Schedule

Start Invited? Item
1:30 PM C3-1 Growth of Functional Nanoporous Thin Films
K. Robbie (Queen's University, Canada)
Thin films deposited from vapor arriving at off-normal incidence exhibit porous nanostructure arising from geometrical shadowing at the atomic scale. The properties of these films differ, sometimes significantly, from those of the constituent materials in bulk form. For examples, magnetic anisotropy, induced by oblique vapor deposition, is exploited in the storage tape used in most consumer video recorders. Recent explorations of these thin films will be discussed, with examples of fractal growth effects, crystal texture, optical filters, photonic crystals, magnetic anisotropy, and biological response. The ultrahigh vacuum evaporator designed specifically for study of these coatings will be described.
2:10 PM C3-3 Optical and Microstructural Properties of Nanocomposite Metal-dielectric Materials Containing Elongated and Aligned Particles Made by Ion Irradiation
J.-M. Lamarre (Ecole Polytechnique de Montreal, Canada); Z. Yu, C. Harkati, S. Roorda (University of Montreal, Canada); L. Martinu (Ecole Polytechnique de Montreal, Canada)
Recent developments in optical technology require new materials for both active and passive devices such as waveguides and switches. In the present work we study nanocomposite films formed by metal nanoparticles (i.e. Au) embedded in a dielectric matrix (SiO2) as a potential material for optical systems. The coatings were deposited by a hybrid technique combining plasma-enhanced chemical vapor deposition (PECVD) and pulsed-DC sputtering. The concentration and spatial distribution of the metal particles were controlled by the deposition parameters, while the particle size and size distribution can be further adjusted by appropriate annealing. Subsequently, the nanocomposite samples were exposed to an energetic ion beam (30 MeV), which transformed the spherical particles to high aspect ratio ellipsoids. The long axes of the ellipsoids are aligned in the direction of the ion beam. The microstructure was studied by spectroscopic-ellipsometry, Rutherford backscattering (RBS) and transmission electron microscopy (TEM).
2:30 PM C3-4 Cermet Coatings for Solar Stirling Space Power
D.A. Jaworske (NASA Glenn Research Center)
Cermet coatings, molecular mixtures of metal and ceramic, are being considered for the heat inlet surface of a solar Stirling space power convertor. In this application, the role of the cermet coating is to absorb as much of the incident solar energy as possible. Cermet coatings are made using sputter deposition, and different metal and ceramic combinations can be created. The ability to mix metal and ceramic at the atomic level offers the opportunity to tailor the compositon and the solar absorptance of these coatings. Several candidate cermet coatings were created and their solar absorptance was characterized as-manufactured and after exposure to elevated temperatures. Coating composition was purposely varied through the thickness of the coating. As a consequence of changing composition, islands of metal are thought to form in the ceramic matrix. Computer modeling indicates that diffusion of the metal atoms plays an important role in island formation while the ceramic plays an important role in locking the islands in place. Much of the solar spectrum is absorbed as it passes through this labyrinth. This paper will discuss the solar absorption characteristics of as-deposited cermet coatings as well as the solar absorption characteristics of the coatings after heating. The role of diffusion and island formation, during the deposition process and during heating, will also be discussed.
2:50 PM C3-5 Gold-alumina Cermet Photothermal Films
B.W. Woods, D.W. Thompson, J.A. Woollam (University of Nebraska-Lincoln)

Cermet films of gold and aluminum oxide were sputter deposited onto silicon substrates. These films consisted of small gold grains embedded in a matrix of aluminum oxide, and were designed to absorb visible radiation and reflect infrared radiation. Ex situ and in-situ spectroscopic ellipsometry were used to characterize film optical constants from vacuum ultraviolet to middle infrared. The optical constants, for cermet films with gold volume fractions ranging from 0 to 1, were used in predictive optical models. Thermal performance was optimized by weighting the fit of the predictive optical models to an ideal reflectance spectrum. The weighting factor emphasized fitting in more significant spectral ranges and deemphasized fitting in less significant wavelength ranges. Emittance and absorptance were calculated along with a new figure of merit based on energy balances. Reflectance data were used to verify film performance.

Research supported by NASA Glenn Research Center grant number NAG3-2219.

3:10 PM C3-6 Advanced Lithography Techniques for Engineering Nanoscale Structures in Photonic Materials
J. Beauvais (Université de Sherbrooke, Canada)

Many research groups both in academia and in industry are currently developing innovative nanoscale devices which could have a tremendous impact in the general areas of photonics and electronics. However techniques for fabricating these devices and nanostructures must be available for use with production tools in order for them to find real applications. There are currently two major approaches under study as fabrication methods for nanodevices: these are microfabrication based techniques and molecular assembly techniques. The microfabrication approach, which is to be discussed here, is strongly based on the technology developed over the past decades for the fabrication of electronic devices and integrated circuits. The continued miniaturisation of these devices has far surpassed expectations for a technology developed initially for micrometer sized structures, and this approach now encompasses the fabrication of devices with dimensions well below 100 nm, even in production environments. There are also methods under study which do not yet meet industry standards in terms of, for example, throughput and repeatability, but which have shown significant promise. These include new techniques such as nano-imprint lithography, as well as established research tools such as electron beam lithography, which are becoming more and more relevant as several equipment manufacturers are now developing new types of production level tools.

The International Techology Roadmap for Semiconductors is the established norm by the semiconductor integrated circuit (IC) industry to assess the technology requirements over the next fifteen years. The objective of this roadmap is to ensure that all the players involved in the development of integrated circuit fabrication technology can focus on the advancements needed in performance in order to meet future generations of semiconductor ICs. It is hard to ignore this roadmap since by definition it covers state of the art microfabrication technology that would appear likely to be put to use for nanodevice fabrication. Lithography is one important aspect of the roadmap and this is of great concern for the development of fabrication techniques suitable for nanodevice fabrication. While the list of candidate technologies for sub-100 nm resolution has evolved over the years, the current list in the roadmap still includes extreme ultraviolet lithography, proximity X-ray lithography, projection electron lithography, direct-write electron lithography, as well as extensions of the current deep ultraviolet (DUV) lithography using schemes such as optical proximity correction and phase shift masks. While it is very debatable as to which one, if any, of these technologies will ever be adopted in a production environment, there is a growing feeling that the industry may adopt a mix and match approach, making use of high resolution but lower throughput techniques such as electron beam lithography for specific applications. And while this latter technique is well known, several recent advances show promise for novel nanodevice fabrication. These include several methods which do away with the problems associated with electron beam resists, problems which become extremely severe at very high resolution. New sensitive layers have recently appeared which can be deposited by evaporation techniques, opening the way for extremely fine lithography patterning on fully 3-dimensional surfaces, well beyond the capabilities of current DUV lithography. This paper will discuss the deposition methods and properties of these new electron sensitive layers, their use in the fabrication of advanced devices, and their impact on the competitive positioning of electron beam lithography with respect to the other competing technologies for the sub-100 nm technology market. Other applications of these new resist materials in other types of lithography (such as the preparation of advanced masks for nano-imprint lithography) will also be addressed.

Time Period TuA Sessions | Abstract Timeline | Topic C Sessions | Time Periods | Topics | ICMCTF2004 Schedule