Papers

AVS2004 Session EW-WeL: Advances in SPM and Other Analytical Techniques

Wednesday, November 17, 2004 12:00 PM in Room Exhibit Hall B

Wednesday Afternoon

Start	Invited?	Item
12:00 PM		EW-WeL-1 Quantitative and Chemical State Analysis of Cross-Sectional GaAs/AlAs Superlattice Using the Newly Developed Scanning Auger Nanoprobe M. Suzuki, N. Urushihara, N. Sanada, A. Yamamoto, H. Iwai, R. Oiwa, Y. Ohashi (ULVAC-PHI, Inc., Japan) Using Auger electron microscopy, so far, because of the electron beam diameter, thermal/mechanical drift and noise, it has been difficult to achieve a spatial resolution of less than 10 nm. The newly developed scanning Auger nanoprobe (PHI-700) consists of a cylindrical mirror analyzer with a coaxial Schottky field emission electron gun and an eight channel multi-channel detector. The instrument is housed in an acoustic isolation chamber in order to secure a vibration-free analysis environment. The secondary electron imaging and Auger signal imaging spatial resolutions are 6 nm and less than 7 nm, respectively, with an electron beam of 1 nA, 20 kV. We have examined Auger observations of cross-sectional surfaces of epitaxially grown GaAs/AlAs superlattice systems with this instrument. It was easy to obtain Auger elemental mapping showing the GaAs(10 nm)/AlAs(10 nm) structure. Generally speaking, Auger signal intensity is in proportion to the atomic density for the element of interest. Although the atomic densities of As atoms in GaAs and AlAs are almost the same, the As intensity from a GaAs layer is extremely different from that from an AlAs layer. Its intensity, defined as peak-to-peak strength in differential spectra, from GaAs layers is twice as strong as that from AlAs layers. It was also found that the Al peak shape gradually changes from the interface with GaAs layer to the center of AlAs layer, though the Ga peak shape does not change at the center of GaAs layer and at the interface. In the presentation, we will detailedly discuss the sensitivity factors in GaAs and AlAs layers and chemical state variation across the cross-sectional multilayer surface.
12:20 PM		EW-WeL-2 Ultimate Nanoprobing in UHV: Four Independent Scanning Tunneling Microscopes Navigated by High Resolution UHV SEM M. Maier, J. Westermann (OMICRON NanoTechnology GmbH, Germany) A main challenge in Nanotechnology is the integration of single nano-devices into large integrated circuits. Device technologies require high resolution topographical and chemical analysis with well established experimental techniques or electrical characterization using standard probing systems. Nevertheless, typical instrumentation lacks from one fundamental problem: Bridging dimensions of a fully integrated circuit down to the nanometer range (or even atomic scale) of single devices by using an adequate integrated navigation system. Moreover, sensitive nano-devices require ultra clean conditions, a goal which is best achieved under true UHV conditions. To meet these new requirements, we have established a new approach integrating state-of-the-art SPM technology with high resolution electron microscopy and spectroscopy: (1) Bridging dimensions and rapid navigation; (2) Combining different surface analysis methods at the very same sample area to gain complementary information; (3) Pushing each single technology to its inherent limits. The UHV NANOPROBE facilitates four independent Scanning Tunneling Microscopes, each one equipped with 3D coarse positioning and full STM capability. A UHV Gemini SEM column with ultimate resolution down to 3nm is used for probe navigation and rapid localization of sample features or devices. STM imaging is engaged to exactly position the local probe. Using STM probe approach technology, a controlled electrical contact is ensured to finally perform a four-point measurement on the nano-scale. Beyond that, the UHV Gemini SEM column itself has unsurpassed performance: Low beam energies down to 100eV avoid sample damage and makes imaging on insulators possible. Beam currents up to 10nA make this electron source an ideal base for high resolution chemical analysis with Scanning Auger Microscopy below the 10nm benchmark.
12:40 PM		EW-WeL-3 Advances in Nanoindentation and Application to Ultra-Thin DLC Films J.M. Burkstrand, S. Downs (Hysitron, Inc.); J.F. Moulder (Physical Electronics, USA) Recent trends in miniaturization of devices and demands for high-performance materials dictate a change in the way that materials are characterized. Understanding of the structure, properties and role of processing at the nanoscale is crucial to achieving the desired performance, regardless of the size scale of the final product. Nanomechanical characterization is a relatively new solution for materials testing, expanding on the range of capabilities of traditional hardness testing. Nanoindentation provides superior lateral and vertical resolution, allowing testing of surface properties or single phases of multi-phase materials. Typical nanoindentation and nanoscratching provide measurement of mechanical properties such as modulus, hardness, fracture toughness, friction coefficients and wear resistance. Hysitron has developed a new technique called modulus mapping which measures the spatial variation of a materialâ?Ts modulus in the near surface region. This nondestructive testing technique has been applied to very thin DLC films, <3 - 10nm, used in the storage industry and has produced some very interesting and exciting results. The modulus maps can quickly distinguish different areas with dissimilar mechanical properties which result from variations in deposition. A more complete picture of the ultra-thin properties emerges when these results are combined with other nanoindentation results and with XPS depth profiles of the same materials.
1:00 PM		EW-WeL-4 Nano-structuring and Nano-manipulation with Scanning Probe Microscopy S. Wu (Molecular Imaging) Nanotechnology extends to all areas of research, from nanodevices to single molecular interactions. Scanning Probe Microscopy provides the perfect tool for nanostructuring and nanomanipulation, so that components such as nanoparticles, nanowires, atoms, and molecules can be analyzed and engineered to nanodevices for applications such as nanoelectronics, drug delivery and disease diagnoses. Molecular Imaging has invested more than 10 years of innovative research in the development of advanced scanning probe technology for controlled environments such as atmosphere, fluid and temperature. The workshop will focus on the application of PicoSPM® system in nanostructuring and nanomanipulation. Nanostructuring will demonstrate examples from both mechanical and electric lithography. Nanomanipulation will discuss examples of pushing and aligning of nanoparticals and nanowires. The study of electronic properties of single molecular wires, and conductive properties of thin films such as self-assembled monolayers with current sensing techniques will also be covered. An in depth review of PicoTREC^TM will be presented. PicoTREC allows simultaneous imaging and mapping of single molecule interactions. Using PicoTREC, reasearchers can quickly distinguish between species that are engaged in molecular binding events and those that are not engaged in molecular binding events thus eliminating the need to perform slow and tedious force spectroscopy experiments to get the same results. It is now possible to conduct molecular recognition experiments with AFM easily and to get results in less time. Scientists can explore dynamic properties of biological systems such as antibody-antigen, ligand-receptor, drug-receptor, DNA-protein, and DNA-DNA.
1:20 PM		EW-WeL-5 Recent Developments in Scanning Probe Microscopy M. Serry (Veeco Instruments) This workshop will introduce new and inventive scanning probe microscopy (SPM) technology including the Digital Instruments EnviroScope that combines modular environmental controls, a sealed hermetic sample chamber, and a wide range of imaging modes to bring superior application flexibility to research and industrial facilities. The EnviroScope allows SPM experiments to be conducted in air, vacuum, and fluid with environmental control. We will also review basic and advanced SPM techniques including force spectroscopy, nanolithography and nanomanipulation, scanning thermal microscopy, and liquid imaging using the Digital Instruments CP-II SPM. These advanced techniques are continuing to be vital to both researchers and educators in the material, physical and life science research areas. The CP-II SPM combines closed-loop scanning, integrated high-magnification color optics, and an intuitive graphical user interface to offer a powerful and easy-to-use scanning probe microscope.