A permanent free tropospheric observatory at Pico summit in the Azores Islands? Past measurements (2001–2005) and future plans.

AGU Fall Meeting. San Francisco, California, 5-9 December 2005.Pico mountain in the Azores Islands provides a base for continuous, free tropospheric measurements that is unique in the central North Atlantic region. The PICO-NARE station was installed there in 2001 as a temporary observatory. However, the location proved ideal for studies of aged emissions from anthropogenic (N. American) and boreal fire (N. American and Russian) emissions, as well as for less frequent interception of European and African plumes. As a result, station operation was continued through summer 2005, and we are planning for continuing operation and conversion into a permanent Portuguese GAW station in the future. This poster will provide an overview of the station, the measurements made there, typical transport pathways to the station and interannual variability in transport, and an overview of the full suite of multi-season observations and key findings from measurements to date. In addition, data availability and near-term and long-term plans for the station's future will be discussed

The Formation of TiN-Encapsulated Cu Interconnects

ABSTRACTA TiN(0)-encapsulated copper structure was made by annealing a Cu-10 at%Ti alloy film evaporated on a SiO2/Si(100) substrate in N2 or NH3 ambiente. During thermal cycling, the tensile stress in the nitridated films is in the range of 200 to 800 MPa. The stress relaxation depends on the cooling cycle and the presence of interlayer between film and substrate. A fast heating rate (70°C/min.) to 550°C in an NH3 ambient can effectively suppress the formation of Cu3Ti and enhance the TiNχ(0) formation near the surface of the copper film. This self-encapsulated Cu structure exhibits good adhesion to SiO2 and oxidation resistance. A fully encapsulated Cu fine line structure can be achieved by annealing a Cu-10at%Ti alloy film in an Ar ambient at 550°C and then in an NH3 ambient at 550°C to form TiOχ/Ti5Si3 adhesion layer and TiN(O) layer, respectively.</jats:p

Stability And Precipitation Kinetics In Si_1-yC_y/Si and Si_1-x-yGe_xC/Si Heterostructures Prepared by Solid Phase Epitaxy

ABSTRACTThis study investigates the stability of Metastable Si1-yCy/Si heterostructures during rapid thermal annealing (RTA) over a temperature range of 1000 – 1150° C Heterostructures of Si1-yCy/Si and Si1-x-yGexCy/Si (x=0.077, y ≤ .0014) were formed by solid phase epitaxy from C implanted, preamorphized substrates using a 30 Minute 700° C anneal in N2. The occupancy of C in substitution lattice sites was monitored by Fourier Transform Infrared Absorption spectroscopy. The layer strain was monitored by rocking curve x-ray diffraction and the structural changes in the layers were determined using plan-view and X-sectional transmission electron Microscopy (TEM). For anneals of 1150° C or above, all the substitutional C was lost from the Si lattice after 30 seconds. TEM verified that the strain relaxation was the result of C precipitating into highly aligned βSiC particles rather than by the formation of extended defects. No nucleation barrier was observed for the loss of substitutional C Preliminary results will also be discussed for Si1-x-yGexCy/Si heterostructures where there is the additional factor of the competition between strain energy and the chemical driving forces.</jats:p

Stability and precipitation kinetics in Si{sub 1{minus}y}C{sub y}/Si and Si{sub 1{minus}x{minus}y}Ge{sub x}C{sub y}/Si heterostructures prepared by solid phase epitaxy

This study investigates the stability of metastable Si{sub 1{minus}y}C{sub y}/Si heterostructures during rapid thermal annealing (RTA) over a temperature range of 1,000--1,150 C. Heterostructures of Si{sub 1{minus}y}C{sub y}/Si and Si{sub 1{minus}x{minus}y}Ge{sub x}C{sub y}/Si (x {equals} 0.77, Y {<=} .0014) were formed by solid phase epitaxy from C implanted, preamorphized substrates using a 30 minute 700 C anneal in N{sub 2}. The occupancy of C in substitution lattice sites was monitored by Fourier Transform Infrared Absorption spectroscopy. The layer strain was monitored by rocking curve X-ray diffraction and the structural changes in the layers were determined using plan-view and X-sectional transmission electron microscopy (TEM). For anneals of 1,150 C or above, all the substitutional C was lost from the Si lattice after 30 seconds. TEM verified that the strain relaxation was the result of C precipitating into highly aligned {beta}SiC particles rather than by the formation of extended defects. No nucleation barrier was observed for the loss of substitutional C. Preliminary results will also be discussed for Si{sub 1{minus}x{minus}y}Ge{sub x}C{sub y}/Si heterostructures where there is the additional factor of the competition between strain energy and the chemical driving forces

Metastable Sic and SiGeC Alloys by Carbon Implantation and Solid Phase Epitaxy

ABSTRACTWe demonstrate the formation of metastable Si1-yCy and Si1-y-xGexCy alloys by C ion implantation and solid phase epitaxial regrowth. Carbon was introduced into Si and SiGe layers by 5, 12 and 25 keV implants to achieve nearly uniform profiles of 0.7 and 1.4 at.% C. The 0.7 at.% C specimens exhibit the highest quality epitaxial layers after SPE regrowth, whereas in higher C concentration specimens solid phase regrowth was impeded. The localized vibrational mode of C occupying substitutional lattice sites in the diamond lattice provides a signature of the metastable phase and is used to monitor the loss of stability due to precipitation of silicon carbide. The Sic and SiGeC alloys retained substitutional carbon during 30 minute isochronal anneals up to 850°C.</jats:p

Dielectric Function and Band Gaps of Si_1−xC_x AND Si_0.924−xGe_0.076C_x (0≤x≤0.014) Semiconductor Alloys Grown on Si

ABSTRACTWe have characterized the optical properties of heteroepitexial Si1−xCx and Si0.924−xGe0.076Cx (0≤x≤0.014) alloys grown on Si substrates by solid phase epitaxy using spectroscopic ellipsometry. The measured dielectric function confirms that the samples are of good crystalline quality. We determined the E1 and E2 band gaps by lineshape-fitting the features in the second derivative spectra of the dielectric functions. Also, we discuss the shift of the band gaps with C concentration arising from strain and chemical alloying.</jats:p

HREM In-Situ Studies of Electron Irradiation Effects in Oxides

ABSTRACTHigh resolution electron microscope (HREM) studies provide the ability to study desorption and sputtering from the perspective of the analysis of the resultant materials, their structure, composition and atomic registry (orientation with respect to the original,material and the irradiation). This is a neglected facet of surface irradiation effects research, yet it is the most important from the technological point of view. In the current study, surface electron irradiation processes in oxides were studied in-situ in a Hitachi H-9000 HREM operated at incident electron energies of 100–300 keV. It was found that a wide range of processes occur in the HREM which are dependent on the energy and flux of the incident electrons and on the material properties. Both ballistic and electronic irradiation damage was observed and the material responses included surface sputtering, amorphisation, chemical disordering, desorption of O and metal surface layer creation, surface roughening and bulk defect creation.</jats:p