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Presentation of TP1 / DFG research unit 1713 “Sensoric micro- and nano systems

The determination of built-in strain in semiconductor devices with nanometer spatial resolution and high sensitivity is needed for the characterization of nanoscale electronic devices. Kelvin probe force microscopy (KPFM) is an atomic force microscopy-based method that provides the spatially resolved surface potential at the sample surface, fulfilling the requirements on resolution and sensitivity. The contrast observed in KPFM imaging is often attributed to stress, but there are only a few reports on the application of KPFM for quantitative stress analysis [1]. In this contribution we focus on the application of KPFM for analysis of stress in silicon devices, such as copper through silicon vias and silicon membranes. The experimental results are compared with density functional theory calculations of strained silicon. This work provides critical insights into the quantitative determination of stress at the nanoscale that so far has gone largely unnoticed in the scanning probe microscopy community. [1] W. Li, D.Y. Li, J. Appl. Phys. 99, 073502 (2006).

Carbon nanotubes (CNTs) are a promising material for novel sensor and interconnect applications. In both cases, the device performance depends strongly on the electronic properties of the tubes. Methods for tuning the electronic structure and especially the band gap are highly desirable. A computational study of cobalt decorated CNTs, by means of density functional theory, reveals that very few cobalt atoms can have a significant impact on the electronic structure, turning semiconducting CNTs into the metallic state. This is further verified by quantum transport simulations. The influence of different amounts of cobalt is also investigated.

The formation of nickel silicides has been studied by X-ray diffraction experiments using synchrotron radiation (SR). A high temperature chamber was used to investigate the phase formation and transition processes under quasi-static conditions at temperatures from 200 to 650 °C. Samples with different dopants, several metal layer thicknesses as well as samples with and without a 150 A TiN capping layer on single-crystal (001) and polycrystalline silicon substrates were examined. While n-type dopants like P and As had no significant impact on the silicidation processes, boron decreased the range of thermal stability of the low-resistivity phase NiSi. A TiN capping layer shifts both these formation and transition temperatures to higher values.

The direction of current research activities by international producers of ignition elements for airbag systems is developing cheap elements which are possible to be integrated into an ignition microsystem. These integrated ignition element is the most important actuator in the whole airbag system. In conformity with the integration of ignitor structure and electronic parts Si became the basic material. Related materials were selected for functional coatings. The investigations involved preparation, characterization, testing, simulation and reliability of the functional coatings for ignition structures. Poly-Si was used as reference material to compare our results with the literature. Furthermore hydrides of titanium, zirconium and hafnium were investigated. Optimaly conversions of the metallic coatings (deposited by sputtering) after a heat treatment in a hydrogen atmosphere could be observed by X-Ray Diffraction and the nuclearphysical 15N-method (Figure 1). After a heat treatment (110°C, on air) the evaluation of stability over the time was performed by analysing the sheet resistance for TiHx- and HfHx - probes. The divergence of the resistance values related to the start value (without heat treatment) amounts 5% for TiHx and 1% for HfHx. Accordingly to /1/ the thermal stability of the metal hydrides increases from Ti to Hf. To obtain suitable design parameters for the ignition elements, a coupled electrical and thermal simulation was performed by the commercial ANSYS FEM program. Figure 2 shows an example of the good agreement between the curves of the simulated thermal behavior and the measured current. /1/ Streb, Wasserstoff in den Metallen Titan, Zircon und Hafnium, Thesis, Frankfurt am Main, 1984 /2/ Weiß U., Löbner B., Abschlußbericht SIFA-MST, "Schneller Anzünder", Januar 1999 /3/ Weiß U., Dünnschichtanzündelement für pyrotechnische Wirkmassen, Patent DE 19721929

A focused ion beam system working with 35 keV Co+ ions has been used to produce CoSi2 interconnects by means of ion beam synthesis. The capability of maskness patterning of the focused ion beam, ist large depth of focus and the possibility of a dynamic focus control allow the fabrication of interconnects in three-dimensional devices with this method. Investigations have been performed using polycrystalline, amorphous and single crystalline silicon substrates. The influence of implantation does has been studied, the electrical resistance and thermal stability of the interconnects has been measured. For room temperature implantation and annealing at 600°C for 1h resistivities between 34 and 60 µ( cm have been obtained for the various substrate materials. CoSi2 interconnects have been found to be thermally stable up to 700°C. In order to demonstrate this method interconnection lines have been fabricated on the sloped walls of deep anisotropically etched grooves 280 µm.

Siliconoxynitride layers with thicknesses between 5 and 10 nm were grown on (100) oriented silicon by rapid thermal processing (RTP) using either N20 or NH3 as nitridant. In order to study the trapping behaviour at the interface and in die insulator bulk, capacitance-voltage (CV) and current-voltage (IV) measurements have been performed combined with different magnitudes of Fowler-Nordheim stress. In addition, Deep Level Transient Spectroscopy (DLTS) has been applied for interface state detection. Auger Electron Spectroscopy (AES) has been used to obtain depth profiles for Si, N, 0 and C. The deconvolution of die AES signal displays significant peak contributions related to intermedium oxidation states. Nuclear Reaction Analysis (NRA) was successfully applied for hydrogen detection in buried SiOXNY thin films.

A focused beam of Co+ ions has been used to produce CoSi2 interconnects by means of ion beam synthesis. Investigations have been performed using polysilicon, amorphous and crystalline silicon substrates. The influence of implantation dose and annealing temperature on the resistivity has been studied. For room temperature implantation and annealing 600°C for 1h, a resistivity of about 60µ(*cm has been obtained independent of the subtrate type. The CoSi2 layers have been found to be stable up to 700°C. CoSi2 interconnects have been fabricated on the slope walls of 200µm deep anisotropically etched grooves using a dynamic focus control of the focused ion beam.

Paoli Ashe Smith writes his mother during World War I.

Paoli Ashe Smith writes his mother during World War I.

Paoli Ashe Smith writes his mother during World War I.

Paoli Ashe Smith writes his mother during World War I.

Paoli Ashe Smith writes his mother during World War I.

Paoli Ashe Smith writes his mother during World War I.

Paoli Ashe Smith writes his mother during World War I.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.

Enclosed with this letter is a letter to Frank S. Daniel, City National Bank of Tuscaloosa, and a legal document pertaining to Netta T. McCorvey's estate.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.

The digitization of this collection was funded by a gift from EBSCO Industries.

This item also has the thank you card response from the family of T. M. Holley.

Enclosed with this letter is a letter from Henry Tonsmeire to Helen Strudwick and Dotie Vaughan, Demopolis, Alabama, July 8, 1915.