bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chimney-Shaped and Plateau-Shaped Gate Electrode Field Emission Arrays
Authors: Tarntair F. G. , Wang C. C. , Hong W. K. , Huang H. K. , Cheng H. C. 
Published: April 2011

AbstractA triode structure of chimney-shaped field emitter arrays is proposed in this article. This triode structure includes the chimney-shaped emitter, thermal oxidation dioxide, and the plateau-shaped singlecrystalline silicon gate electrode. For the application of the matrix-addressable and large area flat panel display, the uniform structure of the emitters and the yield become critical manufacturing issues when attempting to control nano-meter size features. The uniformity and yield of the chimney-shaped emitters are very well controlled. The nano-sized gate-to-emitter separations can be created by the changing thickness of the insulator. The uniformity of the insulator and emitter material can be controlled within 3% which can be obtained by most large area thin film deposition tools, not by photolithography.
UHV STM of Cesium on Oxygenated Epitaxial Diamond (100) Films
Authors: Stallcup R.E. , Perez J.M. 
Published: April 2011

AbstractThe effects of Cs on oxygenated epitaxial diamond (100) films are studied using ultrahigh vacuum (UHV) scanning tunneling microscopy (STM). The epitaxial diamond (100) films are grown on synthetic diamond substrates using chemical vapor deposition and are boron doped. Before Cs deposition and oxygenation, UHV STM imaging of the epitaxial (100) films reveals a (2×l) dimer reconstruction. After Cs deposition and oxygenation, steps with relatively smooth surfaces are observed using positive tip voltages. Using negative tip voltages, many round bright structures approximately 20 Å in diameter are observed on the surface. We propose that these bright structures are Cs atoms or clusters of Cs atoms. Since these structures are only observed for negative tip voltages, they have a large number of empty states. Our observations are compared with recent theoretical predictions for Cs adsorbed on oxygenated diamond (100).
Field Emission Properties of Ion Beam Synthesized SiC/Si Heterostructures by MEVVA Implantation
Authors: Chen Dihu , Wong S. P. , Cheung W.Y. , Luo E.Z. , Wu W. , Xu J.B. , Wilson I.H. , Kwok R.W.M. 
Published: April 2011

AbstractPlanar SiC/Si heterostructures were formed by high dose carbon implantation using a metal vapor vacuum arc ion source. The variations of the field emission properties with the implant dose and annealing conditions were studied. A remarkably low turn-on field of IV/μm was observed from a sample implanted at 35 keV to a dose of 1.0×1018 cm−2 with subsequent annealing in nitrogen at 1200°C for 2h. The chemical composition depth profiles were determined from x-ray photoelectron spectroscopy and the surface morphology was observed by atomic force microscopy. The formation of a thin surface stoichiometric SiC layer and the formation of densely distributed small protrusions on the surface are believed to be the two factors responsible for the efficient electron field emission.
Theoretical Analysis of Fowler Nordheim Parameterization and RLC Characteristics for Ring Cathode Field Emitter Arrays for Next Generation RF Amplifiers
Authors: Jensen K. L. 
Published: April 2011

AbstractOf all applications for which field emitter arrays (FEAs) are being designed, RF vacuum microelectronics is the most technically challenging application. The current density is typically three orders of magnitude larger than that required for displays (which require < 0.1 A/cm2). Due to their high current density capabilities and instant turn-on, FEAs may be a promising alternative to thermionic emitters for use in Inductive Output Amplifiers (IOAs). An analytical model of a field emitter is used to estimate Fowler Nordheim A and B parameters, effective resistance and capacitance of the array under several GHz modulation, signal propogation lengths, total current and current density, and effects of emitter non-uniformity on the basis of array geometry and materials. Estimates of inductance, resistance, and capacitance are made to estimate the drive power required to produce a bunched electron beam for Inductive Output Amplifier applications. An electronic efficiency of 32% with 15 dB gain may be possible from an array producing 260 mA peak, 71 mA average, current at 10 GHz using a TWT helix 1.51 cm long.
Nanoporous Silica For Low K Dielectrics
Authors: Ramos T. , Rhoderick K. , Roth R. , Brungardt L. , Wallace S. , Drage J. , Dunne J. , Endisch D. , Katsanes R. , Viemes N. , Smith D. M. 
Published: April 2011

ABSTRACTAs integrated circuit sizes decrease below 0.25 microns, device performance will no longer improve at the same rate as for past generations because of RC interconnect delay which becomes significant as compared to the intrinsic gate delay. Parallel approaches to address this are to use a lower resistance metal (i.e., copper instead of aluminum) and to use a dielectric material with a dielectric constant significantly below that of dense silica (∼4). Recently, considerable progress has been made in development of thin films of nanoporous silica for these applications. Advantages include high thermal stability, small pore size, similarity to conventional spin-on deposition processes and spin-on glass precursors and final material (silica). The dielectric constant of nanoporous silica can be tailored between ∼1 and 3 which allows its’ implementation at multiple technology nodes in integrated circuit manufacture.Recent development efforts have been focused on; 1) simpler and more reproducible deposition processes, 2) a more complete understanding of processing-property relationships for this material, 3) scale-up of manufacturing to yield a range of precursor products with stability for at least six months and very high purity, and 4) working with customers to integrate this material into both aluminum/gapfill and copper/damascene process flows. This paper targets several specific issues related to nanoporous silica use including water adsorption, pore size distribution control, processing at commercially viable throughputs, and obtaining thickness and dielectric uniformity across 200 mm wafers and wafer to wafer.
Dielectric Anisotropy of Organic Interlayer Dielectrics Confined in Submicron
Authors: Cho T. H. , Todd E. Ryan , Ho Paul S. 
Published: April 2011

ABSTRACTDielectric anisotropy was studied using two fluorinated polymers(fluorinated polyirnide and fluorinated poly(aryl ether)), which are promising candidate as interlayer dielectrics(LLD). From the measurement of the optical anisotropy, the fluorinated polyimide has larger birefringence than fluorinated poly(aryl ether) because the fluorinated polyimide is a rigid rod-like polymer, while the fluorinated poly(arly ether) has an ether linkage to allow the flexibility. The large optical birefringence in the fluorinated polyimide may indicate the large dielectric anisotropy. The dielectric anisotropy of more flexible fluorinated poly(arly ether) was very similar to the expected anisotropy from optical birefringence, but the fluorinated polyimide with rigid rod-like chains has much smaller dielectric anisotropy than expected in the spin-coated film. From the FTLR spectra of the rigid rod-like polymer, the olecular orientation of the rod-like polymer confined in the submicron gaps is shown to be different from that of the blanket film spin-coated on the substrate. This change of the molecular orientation in the confined submicron gap is responsible for the change of the dielectric anisotropy.
A Novel Method to Determine The Mechanical Properties of Ultra-Thin Films.
Authors: White C. C. , Wu W. L. 
Published: April 2011

ABSTRACTRecent experimental results based on x-ray reflectivity[1, 2], and ellipsometry[3] have demonstrated that physical properties of polymer films thinner than one micron may deviate significantly from bulk values[4]. The mechanical properties of the ultra-thin films (sub-micron) are experimentally difficult to determine with precision. The quartz crystal microbalance is an established technique for measuring properties of polymer thin films of a few microns thick. [5–7] Recently this quartz crystal microbalance technique has been modified for measuring the mechanical properties of sub-micron polymer films with high precision. The details and preliminary results from this recently modified quartz crystal microbalance technique will be presented.
Process Integration issues for Interlevel Dielectric Materials for Sub-quarter Micron Silicon Integrated Circuits
Authors: Parihar Vijay , Singh R. 
Published: April 2011

ABSTRACTThe continued miniaturization towards sub-quarter micron feature size mandates the search for low dielectric constant interlayer dielectric materials. A large number of materials and processing techniques has been suggested, but so far none of the proposed dielectric materials as well as processing techniques have been integrated into standard integrated circuit processing. In this paper, a new approach has been formulated for integration of low-k dielectric materials for future integrated circuits.
Electron Beam Processing for Spin-on Polymers and its Applications to Back-End-of-Line (BEOL) Integration
Authors: Yang J. J. , Gill J. , Kennedy J. , Wang S.-Q. , Forester L. , Ross M. 
Published: April 2011

ABSTRACTThe versatility of e-beam processing provides the capability of tailoring the properties of spin-on polymers. Using different e-beam processing schemes, one can obtain a variety of films such as a homogeneous film with modified properties from the original, a film with variable properties as a function of depth, or a film having two distinct layers. In this paper, we demonstrated how to utilize this advantage of e-beam process to facilitate integration of spin-on polymers in the back-end-of-line manufacturing.
Low-Dielectric Constant SiO(F,C) Films for ULSI Interconnections Prepared by CF4 Plasma Ion Implantation
Authors: Zhou Yuanzhong , Qin Shu , Chan Chung , Chu Paul K. 
Published: April 2011

ABSTRACTPlasma ion implantation (PII) doping technique has been utilized to prepare a new lowdielectric constant (low k) material SiO(F,C). Fluorine and carbon were implanted into SiO2 films by CF4 PII using an ICP plasma reactor. The effective dielectric constant of the films was significantly reduced after PH doping. An analysis of a double layer model indicated that a high quality dielectric layer with a dielectric constant down to 2.8 can be achieved by an optimized PII process. Contrasting to other conventional low-k material techniques, PII process also improved bulk resistivity and electrical field breakdown strength. The improvement possibly resulted from adding carbon into the films. The etching effect of CF4 PII could be beneficial to planarization and gap filling of dielectric interlayer.
Pulsed Plasma Enhanced Chemical Vapor Deposition from CH2F2, C2H2F4, and CHCIF2
Authors: Labelle Catherine B. , Lau Kenneth K. S. , Gleason Karen K. 
Published: April 2011

ABSTRACTPulsed plasma enhanced chemical vapor deposition films have been grown from C2H2F4, CH2F2, and CHCLF2. C-Is x-ray photoelectron spectroscopy (XPS) indicates a prevalence ofC-CF species in the films from C2H2F4and CH2F2, whereas CF2species dominate the films from CHC1F2. The CFxspecies distributions for the films are largely controlled by the competition between CF2-producing and HF elimination reactions in the pulsed plasmas. Dominance by HF elimination produces films with highC-CF and CF concentrations (e.g., CH2F2), whereas dominance by CF2-producing reactions leads to films with higher CF2concentrations (e.g., CHCIF2). The % CF3in the film is lowest for the precursor having the lowest F:H ratio, CH2F2. Little or no hydrogen was detected in the deposited films. Thermal degradation of films from C2H2F4and CH2F2, as probed by solid-state nuclear magnetic resonance (NMR) spectroscopy, shows a loss through CF3detachment and HF elimination. Pulsed plasma films from all three precursors gave dielectric constants of 2.4, with loss tangents on the order of 10−2. Dielectric measurements of pulsed plasma films from hexafluoropropylene oxide (HFPO) gave a dielectric constant of 2.0 ± 0.1 with a loss tangent of 0.009.
Phase Separation Behaviors Of Polyimide Blends
Authors: Ryu C. H. , Bae Y. C. 
Published: April 2011

ABSTRACTWe investigated phase behaviors of polyimide blends such as polyethermide(PEI)/polystyrene(PS), PEI/polyamideimide(PAI), PEI/polyethyleneoxide(PEO), and PAI/PEO systems. Our sample systems exhibited lower critical solution temperature(LCST) phase behaviors. In the PEI/PS system, phase transition occurred near or above the glass transition temperature(Tg) of PS and the critical temperature of the system increased with decreasing molecular weight of PS. For PEI/PAI and PEI/PEO systems, the critical temperature of PEI/PAI system is higher than that of PEI/PEO system. Phase transition temperatures of PAI/PEO systems appeared near or below the melting point of PEO.
The Closed-Form Solutions For The Breakdown Voltages Of 6H-SiC Reachthrough Diodes
Authors: Lee You-Sang , Byeon D.-S. , Choi Y.-I. , Park I.-Y. , Han Min-Koo 
Published: April 2011

ABSTRACTThe closed-form analytic solutions for the breakdown voltage of 6H-SiC RTD, reachthrough diode, having the structure of p+-n-n+, are successfully derived by solving the impact ionization integral using effective ionization coefficient in the reachthrough condition. In the region of the lowly doped epitaxial layer, the breakdown voltages of 6H-SiC RTD nearly constant with the increased doping concentration. Also the breakdown voltages of 6H-SiC RTD decrease, in the region of the highly doped epitaxial layer, which coincides with Baliga'seq. [1].
Hot Spots In 4H Sic P+N Diodes Studied By The Optical Beam Induced Current Technique
Authors: Frischholz M. , Nordgren K. , Rottner K. , Seidel J. , Schöner A. , Bakowski M. 
Published: April 2011

ABSTRACTThe optical beam induced current (OBIC) technique allows a direct imaging of high voltage PN junctions at a microscopic level under reverse operating conditions by measuring the local variation of the photocurrent. In this paper we focus on the application of the UV-OBIC technique for failure analysis of 4H SiC high voltage P+N diodes.4H SiC P+N diodes with a 2-zone junction termination extension were used. The diodes were characterized in terms of reverse leakage current and breakdown voltage. Various devices were chosen for failure analysis on the base of early breakdown and/or excessive leakage current for OBIC measurements to study extrinsic failures. As a reference we selected diodes that blocked more than 2 kV with a leakage current density of typically less than 0.1 μA/cm2.OBIC measurements have been used to detect failures in devices that manifest themselves as peaks or “hot spots” in the photocurrent distribution. Early breakdown of diodes could be attributed to formation of hot spots in the periphery of the diodes. The appearance of a hot spot preceded any noticeable increase in reverse leakage current and is thus a very sensitive tool to identify defective diodes already at low voltage levels.The photocurrent generated by illumination of hot spots has been measured as a function of reverse bias voltage and the current multiplication factor has been determined.
Study of Stimulated Emission in InGaN/GaN Multi-Quantum Wells in the Temperature Range of 175 k to 575 k
Authors: Bidnyk S. , Cho Y. H. , Schmidt T. J. , Krasinski J. , Song J. J. , Keller S. , Mishra U. K. , Denbaars S. P. 
Published: April 2011

ABSTRACTWe present the results of an experimental study on stimulated emission (SE) in optically pumped InGaN/GaN multi-quantum well (MQW) structures in the temperature range of 175 K to 575 K. Samples used in this work consisted of 12 QWs and the GaN barriers were intentionally doped with different Si concentrations. The effect of doping on the SE thresholds of the MQWs were investigated. We observed that the SE spectra were comprised of many narrow peaks of less than I Å full width at half maximum (FWHM). No broadening of the FWHMs of the peaks occurred as the temperature was raised from 175 to 575 K. The SE threshold was measured as a function of temperature and compared with that of a thin GaN film. Low SE thresholds were attributed to high quantum efficiency of the MQWs, possibly associated with large carrier localization. A characteristic temperature of 162 K was derived from the temperature dependence of the SE threshold. The integrated emission intensity versus pumping density was examined for different temperatures. This study shows that InGaN/GaN MQWs are suitable for the development of laser diodes that can operate well above room temperature.
Reaction Processes At The Initial Stage of Diamond Nucleation on The Surface of Si(111)
Authors: Xie Fangqing , Chen Youcun , Zhang Qingzhe , Lin Zhangda 
Published: April 2011

ABSTRACTThe thermal behavior of CHx(x=2–3) radicals and H atoms adsorbed on Si(111) surface was investigated using high-resolution electron-energy-loss spectroscopy (HREELS), quadrupole mass spectrometry (QMS), and low-energy electron diffraction (LEED). We found that CHx(x=2–3) radicals in the top adlayers of saturate adsorption were not stable, and the loose structures among a few top adlayers broke up completely till 550K. TDMS(thermal desorption mass spectrometry) analysis showed significant desorption of atomic hydrogen, CH2 and CH3. In the region of 550K-750K, only H2 was detected by TDMS, and we speculate that the CHx(x=2–3) species catenate each other, and form a network of hydrocarbon, which is possibly the initial stage of diamond nucleation on Si. This formed network was not stable above 800K, C2 hydrocarbon species were observed after the thermal desorption temperature was over 800K. HREELS measurement demonstrated that no H atoms existed when substrate temperature reached 980K. Compared with the result reported by S.-Tong Lee for diamond(Ref. 12), we conclude that low stability of hydrocarbon species on Si is the dominant reason that results in the difficulty of diamond nucleation on perfect Si surface.
Spatial characterization of Doped Sic Wafers
Authors: Burton J. C. , Sun L. , Pophristic M. , Li J. , Long F. H. , Feng Z. C. , Ferguson I. 
Published: April 2011

ABSTRACTRaman spectroscopy has been used to investigate wafers of both 4H-SiC and 6H-SiC. The wafers studied were semi-insulating and n-type (nitrogen) doped with concentrations between 2.1 × 1018 cm−3 and 1.2 × 1019 cm−3. Significant coupling of the A1 longitudinal optical (LO) phonon to the plasmon mode was observed. The position of this peak shows a direct correlation with the carrier concentration. Examination of the Raman spectra from different positions on the wafer yielded a rudimentary spatial map of the carrier concentration. This data is compared with a resistivity map of the wafer. These results suggest that Raman spectroscopy of the LO phonon-plasmon mode can be used as a noninvasive, in situ diagnostic for SiC wafer production and substrate evaluation.
Phase Separation and Ordering in InGaN alloys
Authors: Doppalapudi D. , Basu S. N. , Moustakas T. D. 
Published: April 2011

ABSTRACTWe investigated phase separation and long-range atomic ordering in InGaN alloys grown on (11–20) sapphire substrates by molecular beam epitaxy (MBE). Compositional inhomogeneities were found in films grown at substrate temperatures ranging from 650 – 675°C when the indium content was larger than 20%. Upon annealing to 725°C, these films underwent phase separation, similar to films grown at 725° C.These InGaN films also showed the evidence of long-range atomic ordering, with the order parameter being a function of film composition and the growth parameters. A competition between ordering and phase separation has been observed, suggesting that the driving force for both phenomena is lattice strain in the alloy.
Low-Temperature Homoepitaxial Growth of Gan Using Hyperthermal Molecular Beams
Authors: Michel A. , Chen E. , Thomson D. , Nam O. , Davis R. F. , Lamb H. H. 
Published: April 2011

ABSTRACTIn situ cleaning of MOCVD-grown GaN/AlN/6H-SiC substrates using NH3-seeded supersonic molecular beams was investigated. Removal of surface carbon and oxygen contaminants was achieved by heating at 730°C under a hyperthermal NH 3 beam. Oxygen is removed primarily by thermal desorption; however, carbon removal requires an NH3 flux. Atomically smooth surfaces with regular steps are obtained after NH3 beam cleaning. Homoepitaxial growth of smooth, highly textured GaN films was accomplished at 700°C by employing a 0.61-eV NH3 beam and an effusive Ga source.
GaN Etching in BCl3/Cl2 Plasmas
Authors: Shul R. J. , Ashby C. I. H. , Willison C. G. , Zhang L. , Han J. , Bridges M. M. , Pearton S. J. , Lee J. W. , Lester L. F. 
Published: April 2011

ABSTRACTGaN etching can be affected by a wide variety of parameters including plasma chemistry and plasma density. Chlorine-based plasmas have been the most widely used plasma chemistries to etch GaN due to the high volatility of the GaClx and NClx etch products. The source of Cl and the addition of secondary gases can dramatically influence the etch characteristics primarily due to their effect on the concentration of reactive Cl generated in the plasma. In addition, high-density plasma etch systems have yielded high quality etching of GaN due to plasma densities which are 2 to 4 orders of magnitude higher than reactive ion etch (RIE) plasma systems. The high plasma densities enhance the bond breaking efficiency of the GaN, the formation of volatile etch products, and the sputter desorption of the etch products from the surface. In this study, we report GaN etch results for a high-density inductively coupled plasma (ICP) as a function of BCl3:Cl2 flow ratio, dc-bias, chamber pressure, and ICP source power. GaN etch rates ranging from ∼100 Å/min to > 8000 Å/min were obtained with smooth etch morphology and anisotropic profiles.
The Role of the In Source IN InN Growth from Molecular Beams
Authors: Donovan S. M. , Gila B. , MacKenzie J. D. , Lee K. N. , Abernathy C. R. , Wilson R. G. , Muhr G. T. 
Published: April 2011

ABSTRACTInN has been grown in a gas-source MBE system using an RF nitrogen plasma source and standard TMI, solution TMI and solid In. Both solid and solution TMI produce InN with electron and carbon concentrations ≥ 1020 cm−3. Solution TMI-derived material, however, contains significantly less oxygen (8 × 1018 cm−3 vs. ≥ 1020 cm−3 for solid TMI). While the amine used to liquefy the TMI helps to displace the ether believed to be responsible for the oxygen contamination, it also appears to interfere with the growth, resulting in poorer morphology than for standard TMI. While solid In produced the lowest carrier concentration (≤ mid-1018 cm−3), it also produced the worst morphology of the sources examined, presumably due to poor surface mobility. Based on this data, it appears that carbon can play a significant role in the electrical properties of InN, and that the In source is critical in determining the structural quality.
Double Channel AlGaN/GaN Heterostructure Field Effect Transistor
Authors: Gaska R. , Shur M. S. , Yang J. W. , Fjeldly T. A. 
Published: April 2011

ABSTRACTWe report on a Double Channel A1GaN/GaN Heterostructure Field Effect Transistor, where the bottom channel is formed by a GaN-AlGaN-GaN Semiconductor-Insulator-Semiconductor structure. The series resistance for the bottom channel is strongly dependent on the drain bias. This new design demonstrates that the current carrying capability of AlGaN/GaN HFETs can be enhanced using multi channel structures.