bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interference-enhanced Raman Scattering in Strain Characterization of Ultra-thin Strained SiGe and Si Films on Insulator
Authors: Yin Haizhou , Hobart K.D. , Shieh S.R. , Peterson R.L. , Duffy T.S. , Sturm J.C. 
Published: April 2011

ABSTRACTInterference-enhanced Raman scattering was utilized to characterize strain in ultra-thin strained silicon-germanium (SiGe) and silicon layers on insulator. Strained SiGe and silicon films with thickness ranging from 10 to 30 nm on insulating borophosphorosilicate glass (BPSG) were formed by layer transfer techniques and/or strain manipulation via lateral expansion of strained films. The optical interference of the multiple reflections at the BPSG interfaces can substantially boost the reflectivity at the interfaces. The reflection improves Raman signal from SiGe and/or silicon films by increasing excitation intensity and Raman signal collection in the thin films. With the use of interference-enhanced Raman scattering, strain can be characterized at visible wavelengths for films as thin as 10 nm.
Reduced Pressure - Chemical Vapor Deposition of Ge thick layers on Si(001) for microelectronics and optoelectronics purposes
Authors: Hartmann J.M. , Papon A.M. , Holliger P. , Rolland G. , Billon T. , Rouvière M. , Vivien L. , Laval S. 
Published: April 2011

ABSTRACTGe-based photodetectors operating in the telecommunication wavelength range (1.3-1.6 μm) of silica fibers are highly desirable for the development of optical interconnections on SOI substrates. We have therefore investigated the structural and optical properties of Ge thick films grown directly onto Si(001) substrates using a production-compatible Reduced Pressure Chemical Vapor Deposition system. The thick Ge layers grown using a low-temperature / high temperature approach are in a definite tensile-strain configuration, with a threading dislocation density for as-grown layers of the order of 3×107 cm−2. The surface of those Ge thick layers is rather smooth, especially when considering the large lattice mismatch in-between Ge and Si. The root mean square roughness is indeed of the order of 2 nm only for as-grown layers. The layers produced are of high optical quality. An absorption coefficient α ≈10000 cm−1 @ 1.3μm (4500 cm−1 @ 1.55μm) has been found at room temperature for our Ge thick layers. A 30 meV bandgap shrinkage with respect to bulk Ge (0.77 eV ≎ 0.80 eV) is observed as well in those tensilestrained Ge epilayers.
Phosphorus and Boron Implantation into (100) Germanium
Authors: Suh Y. S. , Carroll M. S. , Levy R. A. , Sahiner A. , King C. A. 
Published: April 2011

ABSTRACTBoron and phosphorus were implanted into (100) Ge with energies ranging from 20-320 keV and doses of 5×1013 to 5×1016 cm−2. The as-implanted and annealed dopant profiles were examined using secondary ion mass spectrometry (SIMS) and spreading resistance profiling (SRP). The first four moments were extracted from the as-implanted profile for modeling with Pearson distributions over the entire energy range. The samples were annealed at 400, 600, or 800°C in nitrogen ambient. The dopant activation and diffusion were also examined and it was found that p-type sheet resistances immediately after boron implantation as low as 18 ohms/sq could be obtained without subsequent annealing.
Impact of Buffered Layer Growth Conditions on Grown-In Vacancy Concentrations in Molecular Beam Epitaxy Silicon Germanium
Authors: Shoukri Kareem M. , Haddara Yaser M. , Knights Andrew P. , Coleman Paul G. , Rahman Mohammad M. , Tatsuyama C.C. 
Published: April 2011

ABSTRACTSilicon-Germanium (SiGe) has become increasingly attractive to semiconductor manufacturers over the last decade for use in high performance devices. In order to produce thin layers of device grade SiGe with low concentrations of point defects and well-controlled doping profiles, advanced growth and deposition techniques such as molecular beam epitaxy (MBE) are used. One of the key issues in modeling dopant diffusion during subsequent processing is the concentration of grown-in point defects. The incorporation of vacancy clusters and vacancy point defects in 200nm SiGe/Si layers grown by molecular beam epitaxy over different buffer layers has been observed using beam-based positron annihilation spectroscopy. Variables included the type of buffer layer, the growth temperature and growth rate for the buffer, and the growth temperature and growth rate for the top layer. Different growth conditions resulted in different relaxation amounts in the top layer, but in all samples the dislocation density was below 106 cm−2. Preliminary results indicate a correlation between the size, type and concentration of vacancy defects and the buffer layer growth temperature. At high buffer layer growth temperature of 500°C the vacancy point defect concentration is below the PAS detectable limit of approximately 1015 cm−3. As the buffer layer growth is decreased to a minimum value of 300°C, large vacancy clusters are observed in the buffered layer and vacancy point defects are observed in the SiGe film. These results are relevant to the role played by point defects grown-in at temperatures below ∼350°C in modeling dopant diffusion during processing.
(A)thermal migration of Ge during junction formation in s-Si layers grown on thin SiGebuffer layers
Authors: Vandervorst W. , Pawlak B.J. , Janssens T. , Brijs B. , Delhougne R. , Caymax M. , Loo R. 
Published: April 2011

ABSTRACTSolid phase epitaxial regrowth (SPER) has been proven to be highly advantageous for ultra shallow junction formation in advanced technologies. Application of SPER to strained Si/SiGe structures raises the concern that the Ge may out diffuse during the implantation and/or anneal steps and thus reduce the strain in the top silicon layer.In the present studies we expose 8-30 nm strained silicon layers grown on thin relaxed SiGe-buffers, to implant conditions and anneal cycles, characteristic for formation of the junctions by solid phase epitaxial regrowth and conventional spike activation. The resulting Geredistribution is measured using SIMS. Based on the outdiffused Ge-profiles the Ge-diffusion coefficient has been determined in the temperature range of 800-1100C from which an activation energy of ∼ 3.6 eV can be deduced. Up to 1050 C, 10 min, even a 30 nm strained film remains highly stable and shows only very moderate outdiffusion.We also have observed a far more efficient, athermal Ge-redistribution process linked to the implantation step itself. This was studied by analysing the Ge-redistribution following an Asimplant (2-15 keV, 5 1014 – 3 1015 at/cm2). It is shown that the energy of the implant species (or more specifically the position of the damage distribution function relative to the Ge-edge) plays a determining factor with respect to the Ge-migration. For implants whereby the damage distribution overlaps with the Ge-edge, a very efficient transport of the Ge is observed, even prior to any anneal cycle. The migration is entirely correlated with the collision cascade and the resulting (forward!) Ge-recoil distribution. The scaling with dose for a given energy links the observed Ge-profile with a broadening mechanism related to the number of atom displacements induced in the sample within the vicinity of the Si-SiGe-transition.
Crystals (A Freshman Seminar): An Exercise on Cooperative and Peer Learning
Authors: Bokreta M. Krimo , Santiago-Avilés J. J. 
Published: April 2011

ABSTRACTWe have found that dividing the class of 20 students in groups of four brings agility to the group logistics and minimizes “defocusing” socialization. These are the teams of peer teachers. Each is responsible in carrying its own weight in the education of the team. They select their own “management” structure, as well as their agenda. The course itself starts with a month of lectures by the instructors and by visitors from other germane departments. The students organize visits to research labs on campus where research on crystalline materials is being performed, and invite researchers in the field to lecture the class. Each meeting period involves discussion of homework problems, where the groups, informally, present their findings. After this initial month, each team selects a topic among a wide gamut of possibilities and clears, with the instructors, the particular focus it wishes to develop further. The selected themes tend to group in science, technology, as well the general “lore” of crystals. So the themes range from the growth of crystals in reduced gravity, through the economic aspects of synthetic diamonds, to the folklore of crystals in healing. The particular selection of a theme is not as important as the way they research the topic, develop it and present it. The teams first present a survey of their topic to the class. We evaluate the presentation in terms of intellectual content and delivery. The students not only receive our feedback but also that of their peers. They have the chance to incorporate the comments in a second report, three weeks after the first when they are supposed to focus more on the initial theme and select a part for a more in-depth study. Final oral and written reports are due at the end of the semester.Through the semester the classroom atmosphere has been that of inquiry, critical thinking, accepting of all points of view and the pursuit of diverse perspectives. The students seem to be able to take with them these attitudes and maintain them in their team meetings and discussions.
Fundamental Study and Oxide Reliability of the MBE-Grown Ga2−xGdxO3 Dielectric Oxide for Compound Semiconductor MOSFETs
Authors: Kwo J. , Hong M. , Mannaerts J. P. , Lee Y. J. , Wu Y. D. , Lee W. G. , Milkap S. , Yang B. , Gustaffson T. 
Published: April 2011

ABSTRACTWe have extended our invented high k dielectrics Ga2−xGdxO3 oxide to compound semiconductors of AlGaAs, InGaAs, and InP, and demonstrated the formation of low leakage, insulating barrier on the (100) surface. Fundamental studies of the MOS diodes consisting of Au/GGG mostly on InGaAs are reported, including the crystal-chemical and electrical properties to address the oxide reliability issue. An atomically abrupt interface between the oxide/GaAs interface was achieved by the MBE growth. Systematic post annealing studies of varying temperature and gas species were carried out to improve the dielectric performance such as the reduction of frequency dispersion, voltage hysteresis, and interfacial state density Dit. We show that our results are essential to device processing based on the oxide, and to establish a viable GaAs MOSFET technology.
Experimental Study of Etched Back Thermal Oxide for Optimization of the Si/High-k Interface
Authors: Barnett Joel , Moumen N. , Gutt J. , Gardner M. , Huffman C. , Majhi P. , Peterson J.J. , Gopalan S. , Foran B. , Li H.-J. , Lee B.H. , Bersuker G. , Zeitzoff P. M. , Brown G.A. , Lysaght P. , Young C. , Murto R.W. , Huff H. R. 
Published: April 2011

ABSTRACTWe have demonstrated a uniform, robust interface for high-k deposition with significant improvements in device electrical performance compared to conventional surface preparation techniques. The interface was a thin thermal oxide that was grown and then etched back in a controlled manner to the desired thickness. Utilizing this approach, an equivalent oxide thickness (EOT) as low as 0.87 nm has been demonstrated on high-k gate stacks having improved electrical characteristics as compared to more conventionally prepared starting surfaces.
Next Generation of Thin Film Transistors Based on Zinc Oxide
Authors: Fortunato E. , Barquinha P. , Pimentel A. , Gonçalves A. , Pereira L. , Marques A. , Martins R. 
Published: April 2011

ABSTRACTWe report high performance ZnO thin film transistor (ZnO-TFT) fabricated by rf magnetron sputtering at room temperature with a bottom gate configuration. The ZnO-TFT operates in the enhancement mode with a threshold voltage of 19 V, a field effect mobility of 28 cm2/Vs, a gate voltage swing of 1.39 V/decade and an on/off ratio of 3×105. The ZnO-TFT present an average optical transmission (including the glass substrate) of 80 % in the visible part of the spectrum. The combination of transparency, high field-effect mobility and room temperature processing makes the ZnO-TFT a very promising low cost optoelectronic device for the next generation of invisible and flexible electronics.
Electrical properties of the La0.8Sr0.2MnO3 thin films on SrTiO3 substrate by an excimer laser metal organic deposition (ELMOD) process at low temperature
Authors: Tsuchiya T. , Yoshitake T. , Shimakawa Y. , Yamaguchi I. , Manabe T. , Kumagai T. , Kubo Y. , Mizuta S. 
Published: April 2011

ABSTRACTThe electrical properties of epitaxial La0.8Sr0.2MnO3 films on a SrTiO3(STO) substrate prepared by changing the laser fluence, the irradiation time and the film thickness using excimer laser metal organic deposition(ELMOD) at 500/cm2, the film showed a 3.9 % maximum temperature coefficient of resistance (TCR: defined as 1/R•dR/dT) which was obtained by the ArF laser irradiation at 80mJ/cm2 for 10min. At a constant fluence of 80mJ/cm2, the Tm (temperature of the maximum TCR) of the La0.8Sr0.2MnO3 films increased from 225K to near 250K with an increase in the irradiation time to 90min at which the TCR was almost 3.9%. The La0.8Sr0.2MnO3 film that showed the maximum TCR of 4.0% at 275K was obtained by the ELMOD process at 500°C using the optimum conditions (Flence:80mJ/cm2, Irradiation time: 90min, Film thickness: 80nm).
Characteristic of hydrogenated Ga-doped ZnO films grown by DC magnetron sputtering using H2/Ar gas
Authors: Takeda Satoshi , Fukawa Makoto 
Published: April 2011

ABSTRACTWe report characteristics of sputtered Ga-doped ZnO films grown in pure Ar (Ar-films) and H2/Ar gas mixture (H2/Ar-films). With increasing water partial pressure (PH2O), the resistivity of Ar-films significantly increased due to the decrease in both free carrier density and Hall mobility. The transmittance in the wavelength region of 300-400 nm for the films also increased with increasingPH2O. However, no significant PH2O dependence of the electrical and optical properties was observed for H2/Ar-films. Secondary ion mass spectrometry analysis revealed that hydrogen concentration in the Ar-films increased with increasing PH2O, indicating that the origin of the incorporated hydrogen is attributed to the residual water vapor in the coating chamber. On the contrary, the hydrogen concentration in H2/Ar-films was almost constant irrespective of PH2O and the concentration is obviously higher than that of Ar-films, indicating that the hydrogen primarily comes from H2 gas and the adsorption species due to H2 gas preferentially adsorb to the growing film surface over residual water vapor. Consequently, the effect of PH2O on the crystal growth was significantly reduced by H2 gas introduction, resulting in stability improvement.
Vibrational Lifetimes of Hydrogen in Silicon: Isotope Effects and MOSFET Reliability
Authors: Lüpke Gunter , Sun Baozhou , Tolk Norman H. , Feldman Leonard C. 
Published: April 2011

ABSTRACTCharacterization of defect and impurity reactions, dissociation and migration in semiconductors requires detailed understanding of rates and pathways of vibrational energy flow, of energy transfer channels and of coupling mechanisms between local modes and the phonon bath of the host material. Significant progress in reaching this goal has been accomplished in recent landmark studies exploring the excitation and dynamics of vibrational states associated with hydrogen in silicon. We describe recent experiments which measure the vibrational lifetime of the Si-H bond in various defect configurations and show the relationship between these lifetimes and silicon MOSFET reliability.
Hydrogen diffusion in polycrystalline boron doped and undoped diamond.
Authors: Ballutaud D. , Boutry-Forveille A. , Laroche J.-M. , Simon N. , Girard H. , Herlem M. , Etcheberry A. 
Published: April 2011

ABSTRACTHydrogen (deuterium used as tracer) diffusion experiments were performed on undoped and boron doped diamond films ([B] = 1019and 1020 cm−3) grown by plasma CVD or hot-filament assisted CVD. The samples were exposed either to a radiofrequency plasma or a microwave plasma at different temperatures between 400°C and 900°C. The deuterium profiles were analysed by secondary ion mass spectrometry (SIMS). The deuterium diffusion was explained mainly in term of trapping on intergranular defects. The passivation of boron acceptors, by B-D complex formation in the deuterium diffused superficial layers of the diamond films, was followed by electrochemical and mercury probe capacitance measurements. The results suggest a strong decrease of the free carrier density, which is in accordance with passivation of free carriers by deuterium trapping on dopant.
A Robust Process for Ion Implant Annealing of SiC in a Low-Pressure Silane Ambient
Authors: Rao S. , Saddow S.E. , Bergamini F. , Nipoti R. , Emirov Y. , Agrawal Anant 
Published: April 2011

AbstractHigh-dose Al implants in n-type epitaxial layers have been successfully annealed at 1600°C without any evidence of step bunching. Anneals were conducted in a silane ambient and at a process pressure of 150 Torr. Silane, 3% premixed in 97% UHP Ar, was further diluted in a 6 slm Ar carrier gas and introduced into a CVD reactor where the sample was heated via RF induction. A 30 minute anneal was performed followed by a purge in Ar at which time the RF power was switched off. The samples were then studied via plan-view secondary electron microscopy (SEM) and atomic force microscopy (AFM). The resulting surface morphology was step- free and flat.
Homoepitaxial growth and characterization of thick SiC layers with a reduced micropipe density
Authors: Tsuchida H. , Kamata I. , Izumi S. , Tawara T. , Jikimoto T. , Miyanagi T. , Nakamura T. , Izumi K. 
Published: April 2011

AbstractGrowth technique for thick SiC epilayers with a reduced micropipe density has been developed in a vertical hot-wall CVD reactor. Micropipe closing by growing an epilayer is possible with a nearly 100% probability for 4H-SiC substrates oriented (0001) and (000-1) off-cut towards either [11-20] or [1-100]. By applying the micropipe closing technique, a high-performance Schottky barrier diode (SBD) was demonstrated on a substrate including micropipes. Growth of low-doped and thick SiC epilayers is also possible with a good morphology at a high growth rate, and 14.4 kV blocking performance was demonstrated using a 210 μm-thick epilayer. Epitaxial growth on (000-1) substrates with low doping and a low epi-induced defect density was also demonstrated. Deep centers and impurities were investigated to determine the effective lifetime killer of the epilayers. Dislocations and stacking faults in epilayers grown on 4H-SiC substrates off-cut towards different directions were also investigated.
PVT Growth of 6H SiC Crystals and Defect Characterization
Authors: Dhanaraj Govindhan , Liu Feng , Dudley Michael , Zhang Hui , Prasad Vish 
Published: April 2011

AbstractSiC single crystals have been grown by seeded sublimation method using physical vapor transport (PVT) system designed and fabricated in our laboratory. A novel multi-segmented graphite insulation has been used for improved heat containment in the hot-zone. Numerical modeling was used to obtain the temperature field and predict various growth parameters. The grown crystals were characterized using AFM, SWBXT and chemical etching.
Atomic Force Microscope Observation of Growth and Defects on As-Grown (111) 3C-SiC Mesa Surfaces
Authors: Neudeck Philip G. , Trunek Andrew J. , Powell J. Anthony 
Published: April 2011

AbstractThis paper presents experimental atomic force microscope (AFM) observations of the surface morphology of as-grown (111) silicon-face 3C-SiC mesa heterofilms. Wide variations in 3C surface step structure are observed as a function of film growth conditions and film defect content. The vast majority of as-grown 3C-SiC surfaces consisted of trains of single bilayer height (0.25 nm) steps. Macrostep formation (i.e., step-bunching) was rarely observed, and then only on mesa heterofilms with extended crystal defects. As supersaturation is lowered by decreasing precursor concentration, terrace nucleation on the top (111) surface becomes suppressed, sometimes enabling the formation of thin 3C-SiC film surfaces completely free of steps. For thicker films, propagation of steps inward from mesa edges is sometimes observed, suggesting that enlarging 3C mesa sidewall facets begin to play an increasingly important role in film growth. The AFM observation of stacking faults (SF's) and 0.25 nm Burgers vector screw component growth spirals on the as-grown surface of defective 3C films is reported.
Growth of Large Diameter Semi-Insulating 6H-SiC Crystals by Physical Vapor Transport
Authors: Yoganathan M. , Gupta A. , Semenas E. , Emorhokpor E. , Martin C. , Kerr T. , Zwieback I , Souzis A. E. , Anderson T.A. , Tanner C.D. , Chen J. , Barrett D.L. , Hopkins R.H. , Johnson C.J. , Yan Fei , Choyke W.J. , Devaty R.P. 
Published: April 2011

AbstractSemi-insulating (SI) 6H-SiC boules up to 110mm in diameter have been grown by Physical Vapor Transport (PVT). SI properties have been achieved by vanadiumc compensation, which resulted in the room temperature electrical resistivity exceeding 2×1011ωcm. Low temperature photoluminescence (LTPL) data shows the presence of the deep intrinsic defect level UD-1 in addition to V4+. The nitrogen-bound exciton (NBE) luminescence is weak in heavily vanadium compensated 6H-SiC.
Coherent Chip-Scale Modeling for Copper CMP Pattern Dependence
Authors: Cai Hong , Park Tae , Boning Duane , Kim Hyungjun , Kang Youngsoo , Kim Sibum , Lee Jeong-Gun 
Published: April 2011

AbstractIn this research, we present an improved and coherent chip-scale model framework for copper bulk polishing, copper over-polishing, and barrier layer polishing. The integration of contact wear and density-step-height models is more seamlessly implemented and addresses inherent shortcomings of the previous model. In the new model, a local density is used instead of the effective density computed by way of a planarization length, and only a contact wear coefficient is used to characterize the long-range planarization capability, thus avoiding the conflict between the planarization length and the contact wear coefficient in capturing topography variation. In addition, the pressure computed for each 240×240 μm block using contact wear is further redistributed, using a linear height vs. pressure model, among 40×40 μm cells within that block. The same model framework is used for different polishing steps, so that it is possible to directly compare basic process characteristics, such as pad stiffness, of different polishing stages. Results with the new model show a significant improvement of the modeling accuracy to less than 100 Å of root mean square error. Furthermore, the new model framework can be adapted for the modeling of multi-level metallization processes.
Metrological Assessment of the Coefficient of Friction of Various Types of Silica Using the Motor Current During ILD-CMP
Authors: Jacobsen Harald , Stachowiak Eric , Zwicker Gerfried , Lortz Wolfgang , Brandes Ralph 
Published: April 2011

AbstractIn the work presented the coefficient of friction (COF) was firstly determined metrologically by a systematic assessment of motor currents for different products of pressure and velocity (p v). With all seven test slurries it could be shown that the inserted energy ECMP is proportional to the product of pressure and velocity. The COF of the parameter domain considered here does not depend on the inserted energy or the product of p v in a first approximation. For all tested slurries it was demonstrated that, both the COF and the removal rate (RR) behave analogously (low COF→ low RR).Measurements of the viscosity η have shown that η is not a constant in the shear rate range relevant for CMP. Using the obtained viscosity values a mean slurry film thickness in the range of 2,5 -C 6 μm could be calculated.