bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Mobility Two-Dimensional Electron Gas in Modulation-Doped Si/SiGe Heterostructures
Authors: Wang P. J. , Meyerson B. S. , Ismail K. , Fang F. F. , Nocera J. 
Published: March 2011

ABSTRACTWe report record-high electron mobilities obtained in the Si/SiGe alloy system via single-junction n-type modulation-doped Si/Si0.7Ge0.9 heterostructurcs grown by the ultra-high vacuum chemical vapor deposition technique. Peak electron mobilities as high as 1,800 cm2/Vs, 9,000 cm2/Vs and 19,000 cm2/Vs were measured at room temperature, 77K and 1.4K, respectively. These high mobilities resulted from excellent Si/SiGe interfacial properties by employing a compositional graded Si/SiGe superlattice prior to the growth of a thick S0.7Ge0.3 buffer, which brought about a dramatic reduction of the threading dislocation density in the active Si channel. Two thin phosphorous-doped layers were incorporated in the SiGe barrier and at its surface to supply electrons to the Si channel and to suppress the surface depletion, respectively. The transport properties of these heterostructurcs were determined to be those of a two dimensional electron gas at Si/SiGe heterointerfaces at low temperatures.
Columnar Structure Growth by Silicon Molecular Beam Epitaxy
Authors: Xie Y. H. , Gilmcr G. H. , Fitzgerald E. A. , Michel J. 
Published: March 2011

ABSTRACTSi columnar structures were fabricated using Si MBE on Si substrates with column sizes in the order of ∼ 100 Å. The objective is to explore a viable approach to fabricate quantum wire structures. The growth of the structures, which was due to the growth instability, was an excellent example of a self-limiting process. The dependence of column morphology on the critical parameters, e.g., Si molecular beam incident angle, substrate temperature, substrate rotation, speed, etc., were demonstrated. Comparison between the experimental and the computer simulation results demonstrated the importance of the latent heat related atom migration as compared to the normal surface diffusion at low substrate temperatures and several A/s beam fluxes. A substrate temperature window (≈125°C) was observed which allowed the fabrication of crystalline micro-columns on Si (100) substrates. RHEED studies indicated that the crystalline micro- columns were heavily twined. The twinning phenomenon was also observed in the computer simulation results and interpreted as a result of the reduction in twin formation energy due to the extremely small dimension of the columns. Thermal stability of the columnar structures is discussed. Finally, photoluminescence studies and some potential applications are also discussed.
Molecular Beam Epitaxial Growth of Very High Mobility Two-Dimensional Electron Gases in Si/GeSi Heterostructures
Authors: Xie Y. H. , Fitzgerald E. A. , Mii Y. J. , Monroe D. , Thiel F. A. , Weir B. E. , Feldman L. C. 
Published: March 2011

ABSTRACTWe report the fabrication of modulation doped Si/Gex Si1−x heterostructures by molecular beam epitaxy. The samples are characterized by Rutherford backscattering spectrometry, cross-sectional transmission electron microscopy, electron beam induced current, Hall measurement, and the magnetoresistance (Shubnikov-de Haas) measurements. Threading dislocation densities of = 106cm−2 are observed for relaxed Ge0.3Si0.7 films on Si (100). The modulation doped structures fabricated on these Ge0.3 Si0.7 films contain two-dimensional electron gases with mobilities ranging from 60,000 to 96,000 cm2/V - s at 4.2 K.
Reduction of p+-n+ Junction Tunneling Current for Base Current Improvement in Si/SiGe/Si Heterojunction Bipolar Transistors
Authors: Matutinović-Krstelj Ž , Prinz E. J. , Schwartz P. V. , Sturm J. C. 
Published: March 2011

ABSTRACTA reduction of parasitic tunneling current by three orders of magnitude in epitaxial p+-n+ junctions grown by Rapid Thermal Chemical Vapor Deposition (RTCVD) compared to previously published ion implantation results is reported. These results are very important for the reduction of base current in scaled homojunction and Si/SiGe/Si heterojunction bipolar transistors. High reduction in tunneling currents allows higher limits to transistor base and emitter dopings. Significant tunneling was observed when the doping levels at the lighter doped side of the junction were of the order of 1×1019cm−3 for both Si/Si and SiGe/Si devices. These results were confirmed by I-V measurements performed at different temperatures. Since the tunneling current is mediated by midgap states at the junction, these results demonstrate the high quality of the epitaxial interface.
Silicon Germanium Heterobipolar Transistor Structures with Extremely High Base Doping
Authors: Kasper E. , Kibbel H. , König U. 
Published: March 2011

ABSTRACTThe complete layer sequence of a SiGe-HBT including the emitter contact is grown by Si-MBE. The base doping level was increased from 1018/cm3 up to 1020/cm3 which resulted in very low intrinsic base sheet resistivities (0.27 kΩ/□ for a 50 nm base). With a base Ge content x = 32 % the highest current gain β=5000 could be obtained. A SiGe spacer between base and collector improved the DC-characteristics considerably.
Channel Profile Engineering of MOSFETs using Delta Doping
Authors: Wood Andrew C. G. , O'Neill Anthony G. 
Published: March 2011

ABSTRACTThe influence of the location, dose and width of the doping spike in a delta doped MOSFET is investigated theoretically. Calculations are performed for a range of n and p type 5M0SFETS, and the importance of each design parameter of the device is assessed. The optimum device has a delta layer around 2 0nm deep, with a sheet doping density around 1012cm−2 for the pMOSFET and 5.1011cm−2 for the nMOSFET. The effect of diffusion of the dopant during processing on the device performance is also considered, and it is found that this causes a shift in the threshold voltage of the device. The layer width should ideally be kept below 5nm.
Subsurface Growth of CoSi2 by Deposition of Co on Si-Capped CoSi2 Seed Regions
Authors: Fathauer R. W. , George T. , Pike W. T. 
Published: March 2011

ABSTRACTAt a growth temperature of 800°C, Co deposited on Si (111) diffuses through a Si cap and exhibits oriented growth on buried CoSi2 grains, a process referred to as endotaxy. This occurs preferentially to surface nucleation of CoSi2 provided the thickness of the Si cap is less tfian a critical value between 100 and 200 nm for a deposition rate of 0.01 nm/s. Steady-state endotaxy is modeled under the assumption that the process is controlled by Co diffusion.
Low Temperature Growth of Group II–A Fluoride Layers on Silicon as Buffer for Heteroepitaxial IV–VI and II–VI Compound Semiconductors
Authors: Blunier S. , Zogg H. , Tiwari A. N. , Maissen C. , Weibel H. , Hoshino T. , Theodoropol S. 
Published: March 2011

ABSTRACTWe present our new development of low temperature (<450°C) MBE growth of group II-a fluorides on Si (111) and infrared sensor fabrication in Pb1−xSnxSe grown on such fluoride layers. The stacked CaF2-BaF2 buffer helps to overcome the large lattice and thermal mismatch between the Si-substrate and the narrow gap chalcogenide. Despite a rather nominal quality of the low temperature grown CaF2 layer, the 200nm thick epitaxial BaF2 top layer is of good structural perfection as judged from RBS channelling yield, RHEED-patterns and microscopy. The fluoride buffers were successfully overgrown with Pb1−xSnxSe and small IR-sensor arrays with up to 10.5μm cut-off wavelength were fabricated in the layers. The performance of these sensors is as good as for sensors fabricated with the high temperature buffer layer growth process.
Gas Source Silicon Molecular Beam Epitaxy
Authors: Hirayama H. , Hiroi M. , Koyama K. , Tatsumi T. , Sato M. 
Published: March 2011

ABSTRACTGas source silicon molecular beam epitaxial (Si-MBE) growth is microscopically governed by a disociative adsorption of silicon hydrides, such as Si2H6 source gas molecules on Si surface. The dissociative adsorption generates SiH species on the surface. From this hydride phase, hydrogen desorbs thermaly. The temperature dependence of the growth rate indicated that the hydrogen desorption from the SiH is the rate limiting step. In HBO2 Knudsen cell doping, B adsorbates block the surface migration. Such a blocking effect can be avoided by B2H6 gas dopant, because of the similar incorpration mechanism of B2H6 to that of Si2H6. However, in PH3 gas doping, a crystal quality degradation was observed at a high doping range due to the preferentially high sticking coefficient of PH3 and the resulting surface dangling bond termination. The selective epitaxial growth of a B doped layer using Si2H6 and B2H6 was applied to a novel structured base fabrication for super self-aligned selectively grown base transistor (SSSBT). A successful achievement of the SSSBT fabrication indicates the high potentiality of gas source Si-MBE to the sub-micron size ultra-high speed bipolar large scale integrated (LSI) circuits.
Epitaxial Growth of Perovskite Type Oxide Films OH Si Substrates
Authors: Ishiwara H. , Mori H. , Jyokyu K. , Ueno S. 
Published: March 2011

ABSTRACTEpitaxial growth conditions of perovskite type oxide films on Si substrates are theoretically considered from a viewpoint of lattice matching. Then, epitaxial growth of SrTiO3 films and BaTiO3 films on Si (100) substrates has been tried, in which in order to deoxidize the SiO2 layers on the substrates, thin Sr layers are deposited prior to deposition of the oxide films. It has been found from X-ray diffraction, reflection high energy diffraction, and Rutherford backscattering analyses that SrTiO3 films grow epitaxially on Si (100) substrates under the optimum conditions of the Sr layer thickness, deposition temperature, and annealing temperature.
Growth of Silicon-Germanium Alloys by Atmospheric-Pressure Chemical Vapor Deposition at Low Temperatures
Authors: Agnello P. D. , Sedgwick T. O. , Goorsky M. S. , Ott J. , Kuan T. S. , Scilla G. , Kesan V. P. 
Published: March 2011

ABSTRACTDichlorosilanc and germane were used to grow silicon-germanium alloys at temperatures as low as 550°C at atmospheric pressure. Germanium mole fractions as high as 44% were obtained and the layers exhibit smooth surface morphology. Silicon-gcrmanium/silicon multilayers with abrupt hctero-intcrfaccs have been achieved. Cross Section Transmission Electron Microscopy, (XTEM) and High Resolution X-Ray Diffraction, (HRXRD) characterization of the hetero-interface abruptness will be presented. Recent results on two-dimensional (2-D) hole mobility structures grown by this technique will also be reported. Selective growth of silicon-germanium on oxide patterned silicon wafers was also demonstrated. A significant feature of the selective deposition is the lack of faceting at the oxide sidcwall, which has been commonly observed in high temperature silicon growth.
Experimental and Model Studies of Dopant Segregation During Growth of Silicon Films by Molecular Beam Epitaxy
Authors: Ni W. -X. , Hansson G. V. , Sundgren J. -E. , Markert L. C. , Greene J. E. 
Published: March 2011

ABSTRACTDopant incorporation and surface segregation are studied for thermal Sb and Al cases. The values of the incorporation probability and the segregation ratio have been mainly determine by SIMS measurements. The doping kinetics is discussed using a multi-site model including high dopant surface coverage effects. The calculated results were in good agreement with experimental data.
Evaluation on Electromigration and Stressmigration of Metal Interconnections by Hardness Measurements
Authors: Nakagawa T. , Miyatake H. , Maeda T. , Kuroda K. , Tokushige N. , Inoue R. , Kudo J. , Ashida T. 
Published: March 2011

ABSTRACTIt is well known that the grain size of interconnections made from aluminum alloys affects electromigration and stressmigration tolerance. The hardness of three kinds of aluminum alloys is measured and it is shown that it has a strong correlation between the grain size of the aluminum alloy films. Stressmigration testing is done for those aluminum alloy films and it is found that the SM tolerance of aluminum films can be judged by the hardness of the films. Electromigration testing is also done and the results also confirm the correlation between EM tolerance and hardness of the aluminum films. Hardness measurements are simple and have the possibility of rough estimation of EM and SM tolerance. This method have the merit of saving time for life test.
Silicon Carbide Whisker Reinforced Aluminum with Improved Temperature Resistance due to the Use of a Phosphate Binder
Authors: Chiou Jeng-Maw , Chung D. D. L. 
Published: March 2011

ABSTRACTSilicon carbide whisker reinforced aluminum with improved temperature resistance, increased tensile strength and decreased coefficient of thermal expansion was obtained by using a phosphate binder instead of a commonly used silica binder for preparing the SiC whisker preform, to which liquid aluminum was infiltrated in order to form the composite. The composite is attractive for applications as a heat sink with a low coefficient of thermal expansion.
Numerical Simulation & Experimental Investigation of SMT Laser Microsoldering Thermal Process
Authors: Chunqing Wang , Yiyu Qian , Yihong Jiang 
Published: March 2011

ABSTRACTIn this paper, a numerical simulation of thermal process in the SMT laser microsoldering joint has been developed, in which, the influence on thermal process of the factors such as the thermal conductivity variation of solder with temperature, light reflection coefficient of the lead wire surface, and heat exchange on the surface of SMT materials all have been considered. In order to carry this numerical calculation practice and prove it's results, the reflexive characteristic of light wave to the SMT materials has been gauged, and the dynamic temperature process of laser microjoint has been measured by a new experimental method which was invented by the authors.The results of numerical simulation have been borne out by the tests, and the influences of heating parameters on thermal process has been analysed in this paper. The conclusions will be advantageous to the further study of the microjoint quality control in the SMT laser microsoldering.
Modelling and Characterization of Submicron P-Channel MOSFET's Locally Degraded by Hot Carrier Injection
Authors: Hassein-Bey A. , Cristoloveanu S. 
Published: March 2011

ABSTRACTThe influence of the localized defective channel region formed by hot carrier injection on the basic characteristics of P-channel transistors is systematically investigated and modeled. A practical method of parameter extraction in stressed P-MOSFET's is proposed. It is based on the comparison of Ids(Vg) characteristics before and after stress in weak and strong inversion.
Impact of Oxygen during Post-Gate Processing on MOS Device Characteristics
Authors: Lee Steven S. , Lo G. Q. , Kwong D. L. 
Published: March 2011

ABSTRACTThe effects of post-gate processing in N2+O2 (0˜40%) ambient (e.g., source/drain annealing, BPSG densification and reflow) on the initial MOS characteristics and reliability are discussed in this study. In comparison with processing in pure N2 ambient, it is found that processing in N2+O2-enriched ambient causes a significant, but, transient low-field breakdown of MOS capacitors on both n- and p-wells when electron injection occurs at the poly-gate/SiO2 interface. As a result, the p-channel MOSFETs with high concentration-O2 (˜40%) processing have an excess (i.e., two orders of magnitude) gate leakage current. The experimental results seem to suggest that the annealing in O2-enriched ambient (vs. pure N2 ambient) may induce positive charges near the poly-gate/SiO2 interface which reduce the electron tunneling barrier. Our results also suggest that the induced positive-charges are annihilated immediately upon the application of electric fields.
Enhanced Gate Oxide Reliability through Fluorine Incorporation and the Influence of Polysilicon Process Variations
Authors: MacWilliams K. P. , Lowry L. E. , Lin S. T. , Song M. , Cole R. , Brown S. 
Published: March 2011

ABSTRACTThere has been some uncertainty as to the impact of fluorine (F) on SiO2 quality and reliability. Several laboratories have shown greatly enhanced quality and reliability with fluorinated oxides, while others have been unable to repeat the results. In addition, the laboratories which have shown enhanced reliability with the fluorinated oxides have differed in their interpretation of the mechanism by which the enhancement occurs. X-ray diffraction stress measurements, partial time dependent dielectric breakdown (TDDB) measurements, SIMS depth profiling, transmission electron microscopy, standard high/low frequency C-V measurements, and hot-carrier aging of variously processed MOSFETs have been used to investigate a variety of fluorinated films. We believe that the apparent lack of consistency of the effects of fluorine on MOSFET reliability between laboratories may be explained by slight variations in the gate polysilicon processing which result in variations in polysilicon morphology. The polysilicon morphology determines both mechanical stress and F diffusion which ultimately impacts interface state density and thus hot carrier reliability.
Properties of SiO2 Films Fabricated by Microwave ECR Plasma Processing with and without Energetic Particle Bombardment During Film Deposition. Part II: Electronic Properties
Authors: Chau T. T , Mejia S. R. , Kao K. C. 
Published: March 2011

ABSTRACTSilicon dioxide (SiO2) films were fabricated by microwave ECR plasma processing at 300°C, the range of the film thicknesses being 200 - 300 Å. Two groups of films were fabricated; group A with the substrates placed in a position directly facing the plasma so that the substrates as well as the on-growing films were subjected to bombardment of energetic particles produced in the plasma, and group B with the substrates placed in a processing chamber physically separated from the plasma chamber in order to prevent or suppress the damaging effects resulting from these energetic particle bombardment. It has been found that group A films are poor in both the capacitance-voltage (C-V) and the current-voltage (I-V) characteristics, possibly due to dust particles created by the gas phase reaction of SiH4 and ionic bombardment and radiation damage during film deposition. Group B films, on the other hands, exhibit good electronic properties. On the basis of their I-V and C-V characteristics, group B films yield an average breakdown strength of about 10 MV/cm, an oxide bulk charge density on the order of 1014 q/cm3 and an interface trap density on the order of 1011 cm−2 eV−1 which are approaching those of high quality thermally grown oxides and they are suitable for use as gate insulator for MOS devices.
Modulated Reflectance and Surface Topography Imaging: New Tools for Microelectronics Reliability
Authors: Smith W. Lee 
Published: March 2011

ABSTRACTNew methods of probing beyond the limits of optical penetration have been developed using sensitive laser modulated reflectance techniques. Coupled with this subsurface defect detection method is a new surface topography imaging method. Together, these techniques nondestructively produce submicron-resolution images of surface and subsurface inhomogeneities in microelectronic structures. The measurables of these techniques are related to current reliability subjects. In interconnect metalization processes, defects such as stress- and electromigration-induced voids, precipitates of silicon or copper, sidewall notches, and hillocks and pits are images with these techniques. Sequential stressand-probe nondestructive testing allows the growth rate and other dynamical processes to be documerited. In silicon substrates, metal contamination and crystallographic defects are detected. In this talk, the measurement techniques are described and examples of their usage for VLSI reliability improvement are related.
Investigations of Residual Chlorine on Etched AlCu Metal Lines by Total Reflection X-Ray Fluorescence (TXRF)
Authors: Hockett R. S. , Herman M. H. , Mu X. C. , Ma Li-Jia 
Published: March 2011

ABSTRACTThe present trend in the silicon IC industry is toward the replacement of AlSi metallization by AlCu(Si). However, the addition of Cu to Al(Si) increases the sensitivity of the metallization to moisture corrosion. Total reflection X-Ray Fluorescence (TXRF) with a detection limit in the 1012 atoms/cm2 range is used to measure the residual Cl on Al(Cu) as a function of processing. The results indicate that significant Cl can remain even after standard ash and chemical solvent resist removal. Furthermore, a need is identified to study some unexpected sources of Cl (e.g., air) and the chemistry of its removal from Al films, and this can be now be done easily using TXRF.
Metastable Pitting Corrosion of Aluminum, Al-Cu, and Al-Si Thin Films in Dilute HF Solutions and its Relevancy to the Processing of Integrated Circuit Interconnections
Authors: Scully J. R. , Peebles D. E. 
Published: March 2011

ABSTRACTWe have investigated the pitting corrosion of Al, Al-Cu, and Al-Si thin films in dilute hydrofluoric acid solution. Additions of Cu and, to a lesser extent, Si cause an increase in open circuit potentials (OCP), pit densities and pit sizes as compared to pure Al. Pits in Al-Cu alloys are associated with Cu depleted grain boundaries which are galvanically coupled to adjacent θ-phase precipitates. Pits formed in Al-Si alloys are associated with the Al matrix which is galvanically coupled to Si nodules. θ-Al2Cu has different electrochemical characteristics than Al even though both maintain a thin Al surface oxide. θ-Al2Cu has a more positive OCP, above the average pit repassivation potential for pure Al. Since θ-Al2Cu supports cathodic reactions at enhanced rates compared to pure Al, its presence raises the potential of the adjacent pure Al grain boundary to values near its average breakdown potential and above its average repassivation potential. Metastable pitting is thus promoted.
Sub-Micron Contact Filling and Electromigration of Selfion-Enhanced Physical Vapor Deposited Aluminum Films
Authors: Hummel R. E. , Malone D. W. 
Published: March 2011

ABSTRACTThe electromigration resistance, the sub-micron contact area filling capability, the crystal structure, the preferred orientation, and the CMOS device characteristics of self-ion-enhanced physical vapor deposited aluminum metallizations have been studied. It has been found that optimal conditions can be achieved by increasing the deposition rate and by applying some ionization and acceleration of the aluminum particles.