bluuebunny/crossref_metadata_2025_split huggingface dataset:
Strain Measurements in a Thermally-Cycled Flip-Chip PBGA Solderball
Authors: Drexler E. S. 
Published: April 2011

AbstractThe mismatch between the coefficients of thermal expansion of silicon chips and their organic substrates has been mitigated through the practice of using underfill in flip-chip packages. Yet solder fatigue and package failures still occur. This is particularly true for flip-chips on organic substrates that are thermally cycled between low (−55 °C) and high temperatures (125 °C). In this study, I used electron-beam moir6 to measure displacements and calculate strains in a solderball contained in a flip-chip plastic-ball grid array package. A crossed-line grating with a pitch of 450 nm was used to allow detailed measurements of the local displacements from a cross section of a flip-chip package. Elastic displacements were observed and measured, and the v-field displacements, out of the plane of the chip, were more significant than the shear or u-field, in the plane of the chip, displacements. Larger v-field displacements were measured near the center of the silicon chip than at the edge of the chip.
Effect of Cu on Al Interfacial Mass Transport in Bamboo Rie and Damascene Al(Cu)
Authors: Proost J. , Li H. , Witvrouw A. , Maex K. 
Published: April 2011

AbstractIn this work, the electromigration (EM)-behaviour of bamboo RIE and damascene Al(Cu) interconnects has been studied by drift experiments. For RIE lines, both lattice and interface EM can be operative, depending on the Cu-distribution. Cu-alloying only retains its retarding effect for Al-diffusion at metallic interfaces, while the accompanying presence of an incubation time was found to become rate-controlling for the EM-performance at operating conditions. Contrary to the case of polycrystalline lines, the higher EM-threshold still observed for bamboo damascene relative to RIE is now insufficient to compensate for the significantly increased Cudepletion rate in bamboo damascene due to both geometrical and metallurgical reasons.
Silicide Contacts for Sub-0.25 μm Devices
Authors: Chen L. J. , Cheng S. L. , Chang S. M. , Peng Y. C. , Huang H. Y. , Cheng L. W. 
Published: April 2011

AbstractLow resistivity TiSi2, CoSi2 and NiSi are the three primary candidates for metal contacts in sub-0.25 μ m devices. In the present paper, we review recent progress in the investigations of lowresistivity contacts, which include enhanced formation of C54-TiSi2 on (001)Si by tensile stress, high temperature sputtering, and interposing Mo or TiN layer, improved thermal stability of C54-TiSi2 by the addition of N2 during Ti sputtering or N implantation in (001)Si, self-aligned formation of CoSi2 on the selective epitaxial growth silicon layer on (001)Si, effects of stress on the epitaxial growth of CoSi2 on (001 )Si, improvement of thermal stability of CoSi2 by nitrogen ion implantation or high temperature sputtering, and improvement of thermal stability of NiSi by nitrogen ion implantation or compressive stress.
Diffusion Barriers for Mobile Ions in 256M DRAMs
Authors: Gambino J. P. , Parks C. C. , Hegde S. , Domenicucci A. G. 
Published: April 2011

AbstractIn this study, we investigate the diffusion of mobile ions through thin PSG or SiN layers using secondary ion mass spectrometry (SIMS). The diffusivity of Na through either layer is about 100,000X slower than through SiO2. Hence, thin layers of these materials are effective barriers for short anneals at 400°C. However, there is significant diffusion of both Na and K through these layers at 550°C. This suggests that improved cleans will be required to remove mobile ion contamination after interconnect processes.
Effects of Seeding Layers on Electroless Copper Deposition
Authors: Liu Kai Yu , Tse Man Siu , Goh Wang Ling 
Published: April 2011

AbstractCopper has been actively pursued as the most promising candidate for replacing the current Al metallization for ULSI interconnection because of its higher electrical conductivity and resistance to electromigration. In this work, we present our experimental results on electroless copper deposition on various seeding layers from a formaldehyde-based solution with EDTA as a complexing agent. For electroless plating, a seeding layer is essential for the initiation of copper deposition. X-ray diffraction analysis revealed a variation in the crystallographic orientation of the electroless deposited copper with different underlying seeding layers. The seeding layer is the key factor affecting copper nucleation and grain growth. The initial nucleation behaviors of electroless copper deposition on palladium and copper seeding layers were investigated. The microstructure of electroless deposited copper blanket films was studied using both SEM and AFM, and the crystallinity was analyzed using XRD. The crystal orientation and surface texture of the electroless deposited copper films could be modified by thermal annealing in vacuum (10E-6 Torr) for 30 min at temperatures ranging from 200°C to 300°C. The ratio of crystal orientation, I(111)/I(200) increased with higher annealing temperature, indicating enhanced growth of the (111) crystal structure.
Stress Enhanced Arsenic Diffusion In Titanium Salicided Junctions By Implantation Into C49 TiSi2 and Rapid Thermal Annealing
Authors: Sohn Dong Kyun , Park Ji-Soo , Bae Jong-Uk , Hub Yun-Jun , Park Jin Won 
Published: April 2011

AbstractWe studied reverse leakage current in n+/p titanium-salicided shallow junctions using C49 Ti-silicide as a diffusion source. After Ti deposition, rapid thermal annealing (RTA) was performed to form the C49 Ti-silicide. Subsequently, arsenic ions were implanted and a 2nd RTA was carried out at 850 °C to form the low resistivity C54 Ti-silicide. In spite of no drive-in process following the 2nd annealing, the implanted As diffused well into Si substrate and the reverse leakage current of the n+/p junctions was reduced to two orders of magnitude lower. Since the high chemical affinity of As to Ti-silicide trapped the dopant in the silicide, it has been known that Ti or Ti-silicide cannot be used as a diffusion source. However, in this work, we found that the C49 Ti-silicide acted as a diffusion source of As ions. The reason of fast diffusivity is attributed to the generation of high tensile stress induced by As implantation.
X-ray Photoelectron Spectroscopic Studies of Cu-AI alloy/SiO2 Interfaces
Authors: Wang Pei-I , Yang G. -R. , Murarka S. P. , Lu T. -M. 
Published: April 2011

AbstractCu-Al alloys have been recommended for application as the diffusion barriers/adhesion promoters for advanced copper based metallization schemes. In this study interfacial reaction between Cu-Al alloy/SiO2 is investigated by x-ray photoelectron spectroscopy (XPS). A set of thin Cu-Al alloy films, about 30Å in thickness, are deposited on SiO2 substrates. These were directly examined by XPS. This is followed by a study of the interface formation during bias temperature stressing (BTS) of metal/dielectric interfaces in Cu/Cu-5at.%AI/SiO2 subjected to the electrical testing. Core-level spectra of silicon and aluminum obtained indicate that the reduction of silicon dioxide initiates at room temperature when the aluminum concentration in the copper alloys reaches about 5 atomic percent. The silicon diffusion into metal or vice versa is found to be suppressed during the low temperature anneal (300°C) by the Al2O3 interfacial layer. Also, a difference is present in the observed chemical states and interfacial reaction progressing between sputter and electron-beam deposited films. The films of Cu doped with Al appear to act as a suitable diffusion barrier and adhesion promoter between SiO2 and Cu.
HDP-FSG Integration in Multilevel Interconnect Devices
Authors: M'saad Hichem , Vellaikal Manoj , Zhang Lin , Witty Derek 
Published: April 2011

AbstractHDP-FSG has been integrated as an inter-metal dielectric in a multilevel interconnect scheme. Process regimes for obtaining stable HDP-FSG films were identified. Gap-fill of high aspect ratio structures was achieved for 0.18µm technology node. HDP-FSG film stability, homogeneity, and impurity content were evaluated. In addition to the development of the HDP-FSG process, integration of the interconnect module was investigated and optimized. Analysis of the AI/FSG interface integrity was tested for gap-fill and corrosion with SEM and for fluorine diffusion with SIMS. CMP rate of the FSG was determined and compared to HDP-USG. Al metallization integration approaches in conjunction with FSG were identified.
Integration Challenges of Inorganic Low-K (K≤2.5) Materials with Cu for Sub-0.25µm Multilevel Interconnects
Authors: Yu K. C. , Defilippi J. , Tiwari R. , Sparks T. , Smith D. , Olivares M. , Selinidis S. , Zhang J. , Junker K. , Braekelmann G. , Farkas J. , Lee K. S. , Filipiak S. , Lindell M. , Watanabe J. K. , Wetzel J. T. , Jawarani D. , Herrick M. T. , Cave N. G. , Hobbs C. C. , Stankus J. J. , Mora R. , Freeman M. , Van Gompel T. , Denning D. , Fowler B. W. , Garcia S. , Newton T. , Pena D. , Keyes C. , Nguyen T. , Kirksey S. , Neil T. , Conner J. , Lee J. J. , Fox R. , Hershey R. , Crabtree P. , Sieloff D. D. , Blumenthal R. , Weitzman E. J. 
Published: April 2011

AbstractThe recent introduction of dual inlaid Cu and oxide based interconnects within sub-0.25μm CMOS technology has delivered higher performance and lower power devices. Further speed improvements and power reduction may be achieved by reducing the interconnect parasitic capacitance through integration of low-k interlevel dielectric (ILD) materials with Cu. This paper demonstrates successful multi-level dual inlaid Cu/low-k interconnects with ILD permittivities ranging from 2.0 to 2.5. Integration challenges specific to inorganic low-k and Cu based structures are discussed. Through advanced CMP process development, multi-level integration of porous oxide materials with moduli less than 0.5 GPa is demonstrated. Parametric data and isothermal annealing of these Cu/ low-k structures show results with yield comparable to Cu/oxide based interconnects.
Low Dielectric Constant Sicoh Films As Potential Candidates for Interconnect Dielectrics
Authors: Grill A. , Perraud L. , Patel V. , Jahnes C. , Cohen S. 
Published: April 2011

AbstractThe quest to improve the high performance in ULSI circuits, is driving the search for new materials with low dielectric constants (k=2.5–3.0) for the back end of the line (BEOL) interconnect structures. Novel SiCOH films comprising Si, C, O and H, have been deposited by a PECVD deposition technique. The films have been characterized as-deposited and after anneals of up to 8 hours at 400°C. The atomic composition of the films has been determined by RBS and FRES analysis and their optical properties have been determined by FTIR and index of refraction measurements. The mechanical properties have been determined by measurements of stress and of crack development velocity in water. Metal insulator silicon structures have been used to test the electrical properties of the SiCOH films. After an initial stabilization anneal, the SiCOH films are thermally stable up to 400°C have low tensile stresses (<50 MPa), an extremely low crack propagation velocity, and a hydrophobic behavior. According to the deposition conditions the films have dielectric constants in the range of 2.8 to 3.5. These film properties, combined with an easy-to-integrate deposition process indicate that the material has a strong potential as an interconnect dielectric.
Chemical and Thermal Stability of Fluorinated Amorphous Carbon Films for Interlayer Dielectric Applications
Authors: Chang J. P. , Krautter H. W. , Zhu W. , Opila R. L. , Pai C. S. 
Published: April 2011

AbstractThe thermal and chemical stability of low k fluorinated amorphous carbon (a-C:F) material, deposited by a novel co-sputtering process using both polytetrafluoroethylene (PTFE) and graphite targets was investigated. Thin films of a-C:F with fluorine concentration of 2–55% were deposited, and carbon is observed by XPS in four distinct chemical states, C-C, C-F, C-F2, C-F 3. The relative intensity of C-Fx to C-C increased in intensity with increasing fluorine content and decreasing deposition temperature. Formation of tantalum fluoride was observed upon deposition of tantalum nitride, and the defluorination of the film could lead to reliability and delamination problems.
Wave Polymerization During Vapor Deposition of Porous Parylene-N Dielectric Films
Authors: Erjavec James , Sikita John , Beaudoin Stephen P. , Raupp Gregory B. 
Published: April 2011

AbstractParylene-N films vapor deposited near liquid nitrogen temperature (77 K) undergo a unique ‘wave’ polymerization process in which a rapidly moving reaction front is apparent as the film changes from translucent to optically opaque. This moving reaction front produces a highly porous polymer film. The porosity of these films is approximately 80%. By capturing the wave process on video we have quantified the moving ‘wave’ velocity, which averages 11 cm/s. Timeaveraged deposition rates of the resulting opaque, porous films are more than 8 μm/min. This rate is more than two orders of magnitude greater than the measured deposition rates of nonporous films that are deposited at higher temperatures, at otherwise fixed conditions of monomer delivery rate and deposition chamber pressure.
Effect of Film Thickness and Cure Temperature on the Mechanical Properties of FOx® Flowable Oxide Thin Films
Authors: Liou Huey-Chiang , Pretzer John 
Published: April 2011

AbstractThe mechanical properties and thermal stresses of FOx thin films at different thickness and cured at different temperatures have been investigated by a nanoindentor and a profilometer. In this study, the correlation between structure change, thickness, Si-H/Si-O ratio, modulus, hardness, and calculated coefficient of thermal expansion (CTE) of FOx films have been established. The results show that the modulus of 400°C cured FOx film decreases with increasing film thickness while the hardness slightly varies with increasing film thickness. The calculated CTE of FOx film increases with increasing film thickness. In addition, both the modulus and hardness of FOx films increase with increasing curing temperature. However, the calculated CTE of FOx film decreases with increasing curing temperature. The Si-H/Si-O ratio increases with increasing film thickness but decreases with increasing curing temperature. These results indicate that the increase in modulus and hardness and the decreases in CTE for FOx films are either due to the remaining of Si-H bonds in FOx film at different film thickness or the conversion of Si-H into Si-O when forming the network structure in the FOx film at higher curing temperatures.
Processing and Characterization of Silica Xerogel Films for Low-K Dielectric Applications
Authors: Jain Anurag , Rogojevic Svetlana , Nitta Satya V. , Pisupatti Venumadhav , Gill William N. , Wayner Peter C. , Plawsky Joel L. , Standaert T. E. F. M. , Oehrlein G. S. 
Published: April 2011

AbstractSurface modified silica xerogel films of high porosity (60 - 90 %) and uniform thickness (0.4–2 μm) were fabricated at ambient pressure on silicon and silicon dioxide. The rheological properties that govern film uniformity were determined. A relation between the final dried film thickness and spin speed was developed. The porosity and thickness of the films could be controlled independently. The same porosity could be obtained over a wide range of aging time and temperature combinations. Fracture toughness was measured using the edge-lift-off technique. The best values were comparable to concrete. Surface modification was affected by treating the film with trimethylcholorosilane (TMCS) and other modifiers. Moisture adsorption was studied at 100% RH using a quartz crystal microbalance technique. Depending upon the degree and kind of surface treatment, films absorbed as much as 32% or as little as 2% of their weight in water. Dielectric constants (K), losses and breakdown strengths were comparable to values for calcined, bulk aerogels. Thin (≤ 500 Å) films of Copper (Cu) and Tantalum (Ta) were deposited on xerogel films and subjected to thermal annealing. No diffusion was observed within the limits of RBS. High-density plasma etching showed that the films etch an order of magnitude faster than conventional SiO2 films.
Morphological Transitions in Fluorinated and Non-Fluorinated Parylenes
Authors: Morgen Michael , Zhao Jie-Hua , Rhee Seung-Hyun , Ryant E. Todd , Ho Huei-Min , Plano Mary Anne , Ho Paul S. 
Published: April 2011

AbstractA study of temperature-induced crystallinity changes in fluorinated and nonfluorinated parylene thin films using differential scanning calorimetry, thermal stress and wide angle x-ray diffraction measurements is presented. The nonfluorinated parylene (ppx-N) is shown to undergo two phase transitions between 200°C and 300°C. Both transitions show at least some degree of reversibility. The high temperature (β1-β2) transition is accompanied by a sudden shift in stress, which is attributed to a contraction of the polymers chains. A single, reversible phase transition, occurring between 360°C and 400°C, is observed for fluorinated parylene (ppx-F). This transition is likewise marked by a significant shift in stress, and is apparently due to a similar chain contraction.
Morphological transition of Ge islands on Si(001) grown by LPCVD
Authors: Goryll M. , Vescan L. , Lüth H. 
Published: April 2011

ABSTRACTHut- and dome-shaped islands have been observed during low-pressure vapour phase epitaxy (LPVPE) of Ge on Si(001) at 700°C. The experiments show that a coarsening process occurs in connection with the deposition process, leading to an island height increase with increasing deposition time (total Ge-coverage was kept constant). The shape transition from huts to domes, which takes place after hut clusters have reached a baselength of 80nm, indicates that huts are not a stable configuration. Photoluminescence measurements show a linear correlation between hut cluster density and integrated photoluminescence intensity.
Self-Assembling of Epitaxial Nisi2 In Si(001)
Authors: Teichert S. , Falke M. , Beddies G. , Hinneberg H.-J. 
Published: April 2011

ABSTRACTThe preparation of buried epitaxial layers of a compound ABx in a matrix of the material A can be performed by allotaxy [1]. In the first process step a distribution of ABx precipitates is prepared in the matrix A by codeposition of A and B. This contribution reports on the spatial distribution and the crystallographic orientation of NiSi2precipitates in the Si- matrix. Cross-section transmission electron microscopy was utilized to characterize the samples. The observed depth distribution of Ni in the Si matrix differs remarkably from the calculated distribution given by the deposition rates of Si and Ni. This redistribution of Ni results in two well distinguishable bands of NiSi2precipitates - a narrow one and a broad one - in the Si matrix. The narrow band consists of epitaxial NiSi2 precipitates; and a mixture of epitaxially and twinned grown NiSi2precipitates is formed in the broad band. Under certain deposition conditions self-ordering of the NiSi2precipitates in the narrow band has been observed parallel and perpendicular to the growth direction. In these cases the diameter of the epitaxial NiSi2precipitates varies between 12 and 50 A and the distance between them is in the order of some 10 Å.
Effects of hydrogen in AlAs growth by atomic hydrogenassisted molecular beam epitaxy
Authors: Jang Kee-Youn , Okada Yoshitaka , Kawabe Mitsuo 
Published: April 2011

ABSTRACTThe transition temperature Tc for the AlAs growth to change from/to a nucleation mode and step-flow mode have been studied on vicinal GaAs substrates (A-surface and B-surface) in molecular beam epitaxy (MBE) and atomic hydrogen-assisted MBE (H-MBE) using reflection high-energy electron diffraction (RHEED). The lowering of Tc was clearly observed in H-MBE compared to conventional MBE. For growth of AlAs on vicinal GaAs substrate in H-MBE, atomic H is thought to promote not only the re-evaporation of Al adatoms on the terrace, but also the incorporation of Al at the step edges, thereby facilitating a step-flow growth mode at a lower temperature than in MBE. The differences in the fundamental growth mode between on A-surface and B-surface have also been studies based on the differences in the atomic structure between the two substrates.
Low-Temperature Si (111) Homoepitaxy and Doping Mediated by a Monolayer of Pb
Authors: Dubon O.D. , Evans P.G. , Chervinsky J.F. , Spaepen F. , Aziz M.J. , Golovchenko J.A. 
Published: April 2011

ABSTRACTThe codeposition of Pb during Si (111) molecular beam homoepitaxy leads to high-quality crystalline films at temperatures for which films deposited on bare Si (111) are amorphous. Like other growth mediating elements-- commonly called surfactants-- Pb segregates to the film surface. Ion channeling and transmission electron microscopy reveal nearly defect-free epitaxy for a Pb coverage of one monolayer and temperatures as low as 310 °C. We have deposited films up to 1000 Å in thickness with no indication that this is an upper limit for high-quality epitaxy. However, a decrease in the Pb coverage during growth by only one tenth of a monolayer leads to highly defective films at these temperatures. The codeposition of both As and Pb results in a striking enhancement of the film quality as well. In this case, while the Pb again segregates to the film surface, the As is incorporated into the film with no apparent segregation. Lead-mediated Si epitaxy on As-terminated Si (111) produces high-quality films in which the As remains buried at the substrate-film interface. These results show Pb-mediated Si (111) homoepitaxy to be a promising strategy for the synthesis of layered structures having abrupt nanoscale dopant profiles
Self-Limited GaAs Wire Growth by Movpe and Application to InAs Quantum Dot Array
Authors: Aritsuka Yuuki , Umeda Tetsuhito , Motohisa Junichi , Fukui Takashi 
Published: April 2011

ABSTRACTWe investigate the growth mode and the growth mechanisms of selectively grown GaAs nanometer wire structures by metalorganic vapor phase epitaxy (MOVPE). The nanometer wire structures with (111)A or (111)B facet sidewalls are grown on SiNx masked (001) GaAs with line and space pattern openings. As the growth proceeds, the growth rates increase because Ga atoms migrate from SiNx mask surface and (111) facet sidewalls. After the wire formation with triangular cross section is complete, no further growth occurs on the top of the wires, which is called self-limited growth mode. The shape and width of the top area are observed using a scanning electron microscope (SEM) and an atomic force microscope (AFM), and the mechanism of self-limited growth is discussedWe also simulate the growth rate during selective area growth. From the comparison with the experimental results and the simulation, we estimate the amounts of Ga atom migration from SiNx mask area and (111) facet sidewalls to the wire areas.Finally, we form InAs quantum dots on these GaAs wires, and observe photoluminescence spectra from QDs.
Recent Progress in SiC Microwave MESFETs
Authors: Allen S. T. , Sheppard S. T. , Pribble W. L. , Sadler R. A. , Alcorn T. S. , Ring Z. , Palmour J. W. 
Published: April 2011

ABSTRACTSiC MESFET's have shown an RF power density of 4.6 W/mm at 3.5 GHz and a power added efficiency of 60% with 3 W/mm at 800 MHz, demonstrating that SiC devices are capable of very high power densities and high efficiencies. Single devices with 48 mm of gate periphery were mounted in a hybrid circuit and achieved a maximum RF power of 80 watts CW at 3.1 GHz with 38% PAE.