Bulletin of the American Physical Society
2005 APS March Meeting
Monday–Friday, March 21–25, 2005; Los Angeles, CA
Session U44: Focus Session: Interfaces, Characterization, and Fabrication |
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Sponsoring Units: GIMS Chair: Karen Waldrip, Sandia National Labs Room: LACC 518 |
Thursday, March 24, 2005 8:00AM - 8:36AM |
U44.00001: Combined Surface Analytical Methods to Characterize Degradative Processes in Anti-Stiction Films in MEMS Devices Invited Speaker: The performance and reliability of microelectromechanical (MEMS) devices can be highly dependent on the control of the surface energetics in these structures. Examples of this sensitivity include the use of surface modifying chemistries to control stiction, to minimize friction and wear, and to preserve favorable electrical characteristics in surface micromachined structures. Silane modification of surfaces is one classic approach to controlling stiction in Si-based devices. The time-dependent efficacy of this modifying treatment has traditionally been evaluated by studying the impact of accelerated aging on device performance and conducting subsequent failure analysis. Our interest has been in identifying aging related chemical signatures that represent the early stages of processes like silane displacement or chemical modification that eventually lead to device performance changes. We employ a series of classic surface characterization techniques along with multivariate statistical methods to study subtle changes in the silanized silicon surface and relate these to degradation mechanisms. Examples include the use of spatially resolved time-of-flight secondary ion mass spectrometric, photoelectron spectroscopic, photoluminescence imaging, and scanning probe microscopic techniques to explore the penetration of water through a silane monolayer, the incorporation of contaminant species into a silane monolayer, and local displacement of silane molecules from the Si surface. We have applied this analytical methodology at the Si coupon level up to MEMS devices. This approach can be generalized to other chemical systems to address issues of new materials integration into micro- and nano-scale systems. * This work was supported by the United States Department of Energy under Contract DE-AC04-94AL85000. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration. [Preview Abstract] |
Thursday, March 24, 2005 8:36AM - 8:48AM |
U44.00002: Role of interface in nanocrystalline diamond film internal friction Thomas Metcalf, Xiao Liu, Brian Houston, James Butler, Tatyana Feygelson Nanocrystalline diamond films are an emergent material for use in the fabrication of nanoscale mechanical devices. Because the performance of many mechanical structures is limited by the internal friction of the material from which they are made, understanding the origin of the internal friction of these materials is essential for developing high-quality films and devices. Recent experiments suggest that the mechanical loss of a nanocrystalline diamond film is dominated by the so-called transition region, the initial growth surface of a film that is composed of growing crystallites before they coalesce into a film. This partially amorphous layer is thought to have a substantially higher internal friction than the fully dense nanocrystalline film that subsequently grows. To investigate this, we have prepared several 0.5 $\mu$m thick nanocrystalline diamond films in which the thickness of the transition region varies over a large range. The internal friction and shear modulus of the films were measured between 0.4 K and room temperature. The films are grown on silicon double paddle oscillator substrates, which have an extremely low background internal friction to permit sensitive measurements of film mechanical properties. Subsequent to measurement, the substrate is etched away so that the transition layer of the film can be examined and its characteristics correlated with the film measurements. [Preview Abstract] |
Thursday, March 24, 2005 8:48AM - 9:00AM |
U44.00003: TEM-STM for Novel Nanotechnological Experimentation Joel Vaughn, Martin-E. Kordesch, Saw-Wai Hla We present the design and construction of a miniature scanning tunneling microscope (STM) to be used inside a transmission electron microscope (TEM). In our system, the entire STM head is fitted inside the TEM sample holder, which allows for both TEM imaging/diffraction and STM-tip indentation experiments. The positioning of STM-tip over the desired sample locations can be guided through the real time TEM images. In addition to the nano indentation experiments, the STM program also allows the state-of-the-art control of atom/molecule manipulation procedures [1]. This hybrid TEM-STM system can be used for nanoscale manipulation, electrical characterization and mechanical strength examination of various nanomaterials including nanowires, nanotubes and quantum dots. [1]. S.-W. Hla, K.-F. Braun, V. Iancu, A. Deshpande, Nano Lett. 4 (2004) 1997-2001. This work is financially supported by the NSF-NIRT grant no. DMR- 0304314 and the US-DOE grant no. DE-FG02-02ER46012. [Preview Abstract] |
Thursday, March 24, 2005 9:00AM - 9:12AM |
U44.00004: Photoacoustic Characterization of Nanoelectromechanical Systems A. Kumar, O. Balogun, T. Kouh, Kamil Ekinci, T.W. Murray A photoacoustic microscopy system has been developed to study the nanomechanical properties of Nanoelectromechanical Systems (NEMS). In these experiments, the fundamental flexural resonances of doubly-clamped nanomechanical beams are excited photo-thermally and the resulting displacements are detected using optical interferometry. Our system uses an amplified electroabsorption modulated laser source, and allows excitation at frequencies up to 5 GHz. Femtometer scale displacements of NEMS are detectable using a path-stabilized Michelson interferometer and narrowband phase sensitive detection techniques. Our measurements have enabled the determination of resonance parameters such as resonance frequencies and mechanical quality ($Q)$ factors, elastic constants and mode shapes. The results are compared to a theoretical model for photothermal excitation of doubly clamped beams. Our measurements indicate that photoacoustic microscopy is well suited for the nondestructive evaluation and opto-mechanical operation (actuation and transduction) of NEMS. This project is supported by the NSF under grant No. 0304446. [Preview Abstract] |
Thursday, March 24, 2005 9:12AM - 9:24AM |
U44.00005: Observation of the skin-depth effect on the Casimir force between metallic surfaces Mariangela Lisanti, Davide Iannuzzi, Federico Capasso We have measured the attractive Casimir force between a metallic plate and a transparent sphere covered with a palladium thin film. When the thickness of the coating is less than the skin-depth of the electromagnetic modes that mostly contribute to the interaction, the force is significantly smaller than that measured with a thick bulk-like film. Our results are in agreement with theoretical predictions and are the first direct evidence of the skin-depth effect on the Casimir force between metallic surfaces. [Preview Abstract] |
Thursday, March 24, 2005 9:24AM - 9:36AM |
U44.00006: On the torque on birefringent plates induced by quantum fluctuations Jeremy Munday, Davide Iannuzzi, Federico Capasso, Yuri Barash We present detailed numerical calculations of the mechanical torque induced by quantum fluctuations of the electromagnetic field on two parallel birefringent plates with in plane optical anisotropy, separated by either vacuum or a liquid (ethanol). The torque is found to vary as sin(2$\theta )$, where $\theta $ represents the angle between the two optical axes, and its magnitude rapidly increases with decreasing plate separation d. For a 40 $\mu $m diameter disk made out of calcite which is kept parallel to a Barium Titanate plate at a distance d=100 nm, the maximum torque (at $\theta =\pi $/4) is on the order of $\sim 10^{-18}$ N$\cdot $m. We propose an experiment to observe this torque when the Barium Titanate plate is immersed in ethanol and the other birefringent disk is placed on top of it. In this case the retarded van der Waals (or Casimir-Lifshitz) force between the two birefringent slabs is repulsive. The disk would float parallel to the plate at a distance where its net weight is counterbalanced by the retarded van der Waals repulsion, free to rotate in response to very small driving torques. [Preview Abstract] |
Thursday, March 24, 2005 9:36AM - 9:48AM |
U44.00007: Nonlinear dynamics of micro-opto-mechanical cavities Florian Marquardt, Jack Harris, Steven M. Girvin We present a detailed theoretical analysis of the nonlinear dynamics of a cantilever moving under the influence of radiation pressure, as it carries one of the mirrors of a Fabry-Perot cavity. We will discuss the existence and the properties of multiple stable dynamical attractors, the influence of noise, the possibility of tailoring the effective potential via multi-color laser input, and the effects of the dynamics on the output light. We will comment on the relevance of this analysis for existing and planned implementations of micro-opto-mechanical cavities. [Preview Abstract] |
Thursday, March 24, 2005 9:48AM - 10:24AM |
U44.00008: Novel Method for Gas Sampling Nanoliter MEMS Packages to Determine Hermeticity Invited Speaker: Microelectromechanical systems (MEMS) are attractive for applications requiring complicated, small electrically operated ``machines.'' These complicated devices typically contain many moving parts and very large voltage gradients can exist across material interfaces. Thus, proper control of the internal atmosphere is a crucial requirement. The most definitive way to assess the hermeticity of the package is to sample and analyze the gas. MEMS packages are of various sizes and have internal volumes that range from about a milliliter down to tens of nanoliters. As the MEMS package size decreases, characterization of the internal atmosphere becomes increasingly difficult. Analysis of gases within milliliter-sized volumes is challenging enough with conventional technology; however, nanoliter-sized volumes are impossible. In this paper, we present a newly developed method for sampling a variety of MEMS packages, including those that have an internal volume of 30 nanoliters. The approach that was developed is radically different from standard techniques because of the custom hardware used and the pulsed method for gas introduction into the residual gas analyzer. This change enables not only the analysis of these small MEMS packages, but also a rapid way to analyze the gases repetitively in a statistically significant manner (e.g., gas from each package was analyzed \textit{dozens of times during a 20 minute time period}). Challenges resulting from this paradigm shift include calibration, and sample and manifold preparation (will also be discussed). [Preview Abstract] |
Thursday, March 24, 2005 10:24AM - 10:36AM |
U44.00009: Bottom-up Fabrication of Nanoelectromechanical Systems by Two-layer Nanoimprint Lithography Chien-Chih Huang, Taejoon Kouh, Kamil L. Ekinci Nanoelectromechanical Systems (NEMS) are being developed for a variety of applications as well as for accessing new regimes of fundamental research. NEMS are electromechanical systems --- much like Microelectromechanical Systems (MEMS) --- mostly operated in their resonant modes, with dimensions in the deep submicron. Up to now, for the most part, researchers\textbf{ }have employed ``\textit{top-down}'' techniques to create NEMS devices from semiconductor materials --- i.e., high-resolution lithography followed by various etching techniques. Here, we describe a ``\textit{bottom-up}'' imprint lithographic approach to fabricate freely suspended nanomechanical beam resonators. In this approach, we first fabricate an anchor layer upon the wafer using nanoimprint lithography and film deposition. A subsequent step of imprint upon the anchors followed by thin film deposition and lift-off creates the suspended nanomechanical devices. We have used optical displacement detection techniques to characterize the electromechanical properties of our devices. [Preview Abstract] |
Thursday, March 24, 2005 10:36AM - 10:48AM |
U44.00010: Piezoelectric Aluminum Nitride Thin Films Deposited onto Metal Layer for Micromachined Ultrasonic Transducers Qianghua Wang, Jianzeng Xu, Changhe Huang, Ratna Naik, Gregory W. Auner Aluminum nitride (AlN) thin films were deposited onto metal on silicon substrates by plasma source molecular beam epitaxy (PSMBE) system. The low deposition temperature of 300-450 deg. C was chosen to make the process compatible with standard Si IC technology. X-ray diffraction (XRD) data show highly textured c-axis oriented films with strong (0002) AlN peaks. Micromachined ultrasonic transducers (MUT) have been successfully fabricated using Al/AlN/Al sandwich structure on silicon resonator. Electrical properties of AlN thin films and MUT devices were systematically characterized. The resonance of the flexural acoustic mode of our MUTs was determined at about 200kHz from the impedance measurements. The effective couple factor was derived from the resonant frequency and anti-resonant frequency of MUT devices. The development of this technology would have a great potential in the integration of acoustic sensing/transducing with MEMs technology. [Preview Abstract] |
Thursday, March 24, 2005 10:48AM - 11:00AM |
U44.00011: Nanostructured electron beam deposited resonator combined with nanoparticles for mechanical single-electron transport Hyun Kim, Hua Qin, Robert Blick We present an integrated approach to build nano- electromechanical systems for single electron transport devices. By combining electron beam lithography with nanoparticles and direct three-dimensional electron-beam induced carbon growth, we have developed a scheme for fabricating an electromechanical single-electron transistor (emSET) for ultra-high frequencies. This process commands a size reduction of the metallic island and an improvement of the mechanical forces involved. We demonstrate how to combine two fabrication techniques for the realization of NEMS-SET devices. This will finally leads to Coulomb blockade effects and mechanical resonances in the GHz range. [Preview Abstract] |
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