bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of Silicon Nitride Films Prepared by Combination of Catalytic-Nitridation and Catalytic-Cvd
Authors: Izumi A. , Kikkawa A. , Higashimine K. , Matsumura H. 
Published: June 2019

AbstractThis paper reports about the interface of silicon nitride (SiNx) formed on Si(100) prepared by combination of catalytic-nitridation and catalytic-vapor deposition method in a catalytic chemical vapor deposition system. It is found that flat interface of SiNx/Si(100) is formed by inserting nitridation layer before growing the SiNx films.
High-rate (> 1nm/s) and low-temperature (< 400°C) deposition of silicon nitride using an N2/SiH4 and NH3/SiH4 expanding thermal plasma
Authors: Hong J. , Kessels W.M.M. , Sanden M.C.M. van de 
Published: June 2019

AbstractHigh-rate (> 1 nm/s) and low-temperature (50– 400°C) deposition of silicon nitride (a-SiNx:H) films has been investigated by the expanding thermal plasma (ETP) technique using SiH4 as Si-containing and N2 or NH3 as N-containing precursor gases. The structural, optical and electrical properties of the a-SiNx:H films have been studied by elastic recoil detection, spectroscopic ellipsometry, infrared spectroscopy, dark conductivity measurements and atomic force microscopy. The film properties of the ETP deposited a-SiNx:H films in this low-temperature range are discussed in terms of deposition rate, atomic composition, UV-VIS optical and IR vibrational properties, conductivity, and surface topography of the films.
Switch-On Transients And Static Characteristics Of Polymorphous And Amorphous Silicon Thin-Film Transistor
Authors: Tripathi V. , Mohapatra Y. N. 
Published: June 2019

AbstractHydrogenated polymorphous silicon (Pm-Si:H) being an admixture of amorphous and ordered phase silicon shows improved optical and electrical properties due to the presence of nanocrystallites. In order to compare the dynamic and steady state electrical properties in a-Si:H and pm-Si:H, bottom gate Thin Film Transistors (TFT) of these materials were fabricated with SiO2 as the insulating layer. The active materials were deposited using plasma-enhanced chemical vapor deposition (PECVD) by varying pressure, temperature and hydrogen dilution. Transfer characteristics of TFTs made using pm-Si:H show lower leakage current, higher on-current and sharper volt per decade change as compared to similar TFTs made from a-Si:H. Density of states in pm-Si:H as calculated from field effect conductance using incremental method is observed to be an order of magnitude lower than in a-Si:H based devices. To compare dynamic characteristics, we studied the switch-on transient characteristics of polymorphous and amorphous silicon TFTs by pulsing the gate to different voltages in the temperature range of 150-300K. The switch-on transients are trap limited with overall better switching characteristics for pm-Si:H samples. An initial rising transient in case of pm-Si:H is activated with an effective energy of 0.3 eV. The origins of transients are interpreted in terms of trap limited carrier dynamics and charge redistribution within the distribution of localized states.
Dependences of Structural Parameters on the Characteristics of Poly-Si Thin-Film Transistors after Plasma Passivation
Authors: Yu Cheng-Ming , Huang Tiao-Yuan , Lei Tan-Fu , Lin Horng-Chih 
Published: June 2019

AbstractThe effects of NH3 and H2 plasma passivation on the characteristics of poly-Si thin-film transistors with source/drain extensions induced by a bottom sub-gate were studied. Our results show that significant improvements in device performance can be obtained by both passivation methods. Moreover, NH3-plasma-treatment appears to be more effective in reducing the off-state leakage, subthreshold swing, compared to H2 plasma passivation. NH3 plasma treatment is also found to be more effective in reducing the anomalous subthrehold hump phenomenon observed in non-plasma-treated short-channel devices. Detailed analysis suggests that all these improvements can be explained by the more effective passivation of the traps distributed in both the front and back sides of the channel by NH3 plasma treatment.
Photoelectron spectroscopic investigations of very thin a-Si:H layers
Authors: Schmidt M. , Schoepke A. , Milch O. , Lussky Th. , Fuhs W. 
Published: June 2019

AbstractWe report on a detailed study on gap-state distribution in thin amorphous silicon layers (a-Si:H) with film thicknesses between 5 nm and 20 nm on c-Si wafers performed by UV excited photoelectron spectroscopy (UV-PES). We measured how the work function, the gap state density, the position of the Fermi-level and the Urbach-energy depend on the layer thickness and the doping level of the ultra thin a-Si:H(n) layers. It was found, that for phosphorous doping the position of the Fermi level saturates at EF–EV=1.47 eV. This is achieved at a gas phase concentration of 10000 ppm PH3in the SiH4/H2mixture which was used for the PECVD deposition process. The variation of the doping level from 0 to 20000 ppm PH3addition results in an increase of the Urbach energy from 65 meV to 101 meV and in an increase of the gap state density at midgap (EV-Ei= 0.86eV) from 3·1018to 2·1019cm-3eV-1.
Determination of Defect Densities by Constant Photocurrent Method – Comparison of AC and DC Methods
Authors: Main Charlie. , Reynolds Steve , Zrinšća Ivica. , Merazga Amar 
Published: June 2019

AbstractWe report on discrepancies in the absorption spectrum of a-Si:H measured by DC and AC constant photocurrent methods (CPM). Our measurements reveal discrepancies in the absorption coefficient alpha, of up to an order of magnitude. DC measurement gives the higher value for alpha at photon energies below the Urbach tail. In this paper we examine free carrier generation paths in AC CPM, and the influence of these paths on the photocurrent frequency response to modulated sub-gap illumination. A simple kinetic model is used to attempt to explain quantitatively the differences in the photocurrent frequency response for sub- and super-gap excitation. At first sight the basic AC technique is of doubtful validity, even at exciting frequencies as low as 1 Hz, since maintaining a constant AC photocurrent does not guarantee a constant carrier lifetime. On the other hand, the DC method involves several parallel excitation paths, obfuscating attempts to extract a density of states from the absorption spectrum. We demonstrate that a simple variation of AC CPM can provide a more accurate means of determining the density of states than DC CPM.
Metastable Defects in the Amorphous Silicon-Germanium Alloys
Authors: Cohen J. David 
Published: June 2019

AbstractThis paper first briefly reviews a few of the early studies that established some of the salient features of light-induced degradation in a-Si,Ge:H. In particular, I discuss the fact that both Si and Ge metastable dangling bonds are involved. I then review some of the recent studies carried out by members of my laboratory concerning the details of degradation in the low Ge fraction alloys utilizing the modulated photocurrent method to monitor the individual changes in the Si and Ge deep defects. By relating the metastable creation and annealing behavior of these two types of defects, new insights into the fundamental properties of metastable defects have been obtained for amorphous silicon materials in general. I will conclude with a brief discussion of the microscopic mechanisms that may be responsible.
Temperature Dependence of the Decay of Optically Excited Charge Carriers in Amorphous Silicon
Authors: Whitaker J. , Taylor P. C. 
Published: June 2019

AbstractWe report the temperature dependence of the growth and decay of the optically induced electron spin resonance (LESR) on short and long time scales (10-3 s < t < 2500 s). This range of times spans the region between previously published photoluminescence and the LESR data. In addition, we examine the steady-state density of optically excited charge carriers as a function of temperature. These measurements lead to a better understanding of the band tail structure of amorphous silicon as well as the kinetics of the excitation and recombination processes.
Improvement of Gate Oxide Integrity in Low Temperature Poly Silicon TFT
Authors: Lee Seok-Woo , Nam Dae Hyun , Yoon Jin Mo , Seo Hyun Sik , Lim Kyoung Moon , Kim Chang-Dong 
Published: June 2019

AbstractThe electrical characteristics of SiH4-based PECVD gate oxide have been investigated with respect to gate oxide integrity (GOI) and its reliability. It was found that the GOI of poly-Si TFT integrated on glass substrate strongly depended on the charge trapping and deep level interface states generation under Fowler-Nordheim stress (FNS). By applying elevated temperature postanneal without vacuum break after the gate oxide deposition, highly reliable gate oxide was obtained. Under FNS, ID-VG curve showed severe shift and degradation of subthreshold slope, which were reduced by adopting post-annealed gate oxide. Besides, the TFT with post-annealed gate oxide showed around 10 times higher charge to breakdown than that of as-deposited gate oxide. Charge to breakdown of MOS capacitors were also studied. By applying post-annealed gate oxide, charge to breakdown drastically improved, which could be explained by reduced charge trapping under FNS.
Characteristics of Bottom Gate Thin Film Transistors with Silicon rich poly-Si1-xGex and poly-Si fabricated by Reactive Thermal Chemical Vapor Deposition
Authors: Shimizu Kousaku , Zhang JianJun , Lee Jeong-Woo , Hanna Jun-ichi 
Published: June 2019

AbstractIn the fabrication of thin film transistors (TFTs), little attention has been paid to the polycrystalline silicon thin films prepared at low temperatures where the glass substrates are adopted so far. Since the film quality is not sufficient to achieve high mobility, e.g., over 50 cm2/Vs in spite of high benefit in their industrial fabrication. We have fabricated bottom gate TFTs with poly-Si and poly- Si1-xGex thin films deposited at 450°C by newly developed low-temperature LPCVD technique and characterized electrical characteristics of the TFTs: disilane and a small amount of either germanium tetrafluoride or fluorine were used as material gases and helium as carrier gas. Thermal annealing for dopant activation and atomic hydrogen treatment for defect passivation were carried out. We found that the defect elimination process is important for improving TFT performance significantly. Finally the mobility of p-channel and n-channel TFTs have attained 36.3-54.4 cm2/Vs and 57 cm2/Vs, respectively.
Bandtail Limits to Solar Conversion Efficiencies in Amorphous Silicon Solar Cells
Authors: Zhu K. , Yang J. , Wang W. , Schiff E. A. , Liang J. , Guha S. 
Published: June 2019

AbstractWe describe a model for a-Si:H based pin solar cells derived primarily from valence bandtail properties. We show how hole drift-mobility measurements and measurements of the temperature-dependence of the open-circuit voltage VOC can be used to estimate the parameters, and we present VOC(T) measurements. We compared the power density under solar illumination calculated with this model with published results for as-deposited a-Si:H solar cells. The agreement is within 4% for a range of thicknesses, suggesting that the power from as-deposited cells is close to the bandtail limit.
Evolution of Crystallinity in Mixed-Phase (a+μc)-Si:H as Determined by Real Time Spectroscopic Ellipsometry
Authors: Ferlauto A. S. , Ferreira G. M. , Koval R.J. , Pearce J.M. , Wronski C.R. , Collins R.W. , Al-Jassim M. M. , Jones K. M. 
Published: June 2019

AbstractThe ability to characterize the phase of the intrinsic (i) layers incorporated into amorphous silicon [a-Si:H] and microcrystalline silicon [μc-Si:H] thin film solar cells is critically important for cell optimization. In our research, a new method has been developed to extract the thickness evolution of the μc-Si:H volume fraction in mixed phase amorphous + microcrystalline silicon [(a+μc)-Si:H] i-layers. This method is based on real time spectroscopic ellipsometry measurements performed during plasma-enhanced chemical vapor deposition of the films. In the analysis, the thickness at which crystallites first nucleate from the a-Si:H phase can be estimated, as well as the nucleation density and microcrystallite cone angle. The results correlate well with structural and solar cell measurements.
P- and N-Type Microcrystalline SiC Fabricated by rf Plasma CVD with Ethane Gas
Authors: Toyama T. , Nakano Y. , Kosuge T. , Asano A. , Okamoto H. 
Published: June 2019

AbstractWe have been investigated p- and n-type microcrystalline Si1-xCx (μc-SiC) films fabricated by a conventional rf (13.56 MHz) plasma CVD method with a use of a new carbon source of C2H6 gas at a low substrate temperature on a glass substrate. The Si crystallites incorporated in μc-SiC films retain with a carbon content up to 9 at.%. Both of p- and n-type μc-SiC films show relative high dark conductivities of on the order of 10-3 S/cm with optical energy gaps, E04, of~2eV. In infrared spectra, any pronounced features due to C-Hn vibration mode are not found in C2H6-based μc-SiC films, which is different from the case of CH4-based μc-SiC films.
Hot-Wire Chemical Vapor Deposition for Epitaxial Silicon Growth On Large-Grained Polycrystalline Silicon Templates
Authors: Mason M. S. , Chen C.M. , Atwater H.A. 
Published: June 2019

AbstractWe investigate low-temperature epitaxial growth of thin silicon films on Si [100] substrates and polycrystalline template layers formed by selective nucleation and solid phase epitaxy (SNSPE). We have grown 300 nm thick epitaxial layers at 300°C on silicon [100] substrates using a high H2:SiH4 ratio of 70:1. Transmission electron microscopy confirms that the films are epitaxial with a periodic array of stacking faults and are highly twinned after approximately 240 nm of growth. Evidence is also presented for epitaxial growth on polycrystalline SNSPE templates under the same growth conditions.
Structural Evolution of Nanocrystalline Germanium Thin Films with Film Thickness and Substrate Temperature
Authors: Jordan William B. , Carlson Eric D. , Johnson Todd R. , Wagner Sigurd 
Published: June 2019

AbstractThe structure of germanium thin films prepared on glass by plasma enhanced chemical vapor deposition was characterized by Raman spectroscopy, atomic force microscopy (AFM) and field emission scanning electron microscopy (SEM). Crystallinity, surface roughness, and grain size were measured as functions of film thickness and deposition temperature. Grain nucleation was apparent for films as thin as 10 nm. Over the thickness range studied, grain size increased with film thickness, whereas average surface roughness started to increase with film thickness, but then remained fairly constant at approximately 1 nm for a film thickness greater than 25 nm.
Material Aspects of Reactively MF-Sputtered Zinc Oxide for TCO Application in Silicon Thin Film Solar Cells
Authors: Hüpkes Jürgen , Rech Bernd , Kluth Oliver , Müller Joachim , Siekmann Hilde , Agashe Chitra , Bochem Hans P. , Wuttig Matthias 
Published: June 2019

AbstractAl-doped ZnO films were deposited on glass in an in-line system by reactive mid-frequency (MF) magnetron sputtering. The influence of substrate position on the film properties as well as the relation between static and dynamic deposition are studied. All films showed low resistivity (<4x10-4 Ωcm) and excellent transparency (> 80 % in the visible region). The resistivity ρ for substrate positions above the sputter craters (race tracks) is up to a factor of two higher than on other positions where the smallest ρ is 1.9 x 10-4 Ωcm. Major differences in statically deposited films as a function of the position on the substrate are found for the structural film properties as characterized by x-ray diffraction (XRD) and etching behaviour. The different surface textures obtained after etching are directly related to variations in the short-circuit current densities of amorphous silicon p-i-n solar cells prepared on these etched ZnO:Al films.
The a-Si:H Growth Mechanism: Temperature Study of the SiH3 Surface Reactivity and the Surface Silicon Hydride Composition During Film Growth
Authors: Kessels W.M.M. , Barrell Y. , Oever P.J. van den , Hoefnagels J.P.M. , Sanden M.C.M. van de 
Published: June 2019

AbstractWe report on two experimental studies carried out to reveal insight into the interaction of SiH3 radicals with the a-Si:H surface as assumed essential in the a-Si:H growth mechanism. The surface reaction probability β of SiH3 on the a-Si:H has been investigated by spectroscopic means as a function of the substrate temperature (50 - 450°C) using the time-resolved cavity ringdown technique. The silicon hydrides –SiHx on the a-Si:H surface during deposition have been studied by the combination of in situ attenuated total reflection infrared spectroscopy and argon ion-induced desorption of surface hydrogen. For SiH3 dominated plasma conditions, it is found that the surface reactivity of SiH3 is independent of the substrate temperature with β = 0.30±0.03 whereas the silicon hydride composition on the a-Si:H surface changes drastically for increasing substrate temperature (from –SiH3 to =SiH2 to ≡SiH). The implications of these observations for the a-Si:H growth mechanism are addressed.
Effects of Excitation Frequency and H2 Dilution on Cluster Generation in Silane High-Frequency Discharges
Authors: Shiratani Masaharu , Koga Kazunori , Harikai Atsushi , Ogata Takanori , Watanabe Yukio 
Published: June 2019

AbstractReduction of cluster amount in silane discharges is the key to decreasing microstructure parameter Rα of a-Si:H films deposited with the discharges. The cluster amount is found to be reduced more than one order of magnitude using 60 MHz discharges instead of 28 MHz ones or using H2 dilution of an H2/SiH4 ratio of 5. The cluster-suppressed plasma CVD using 60 MHz discharges realizes deposition of a-Si:H films of Rα~ 0 at a fairly high rate of 0.55 nm/s. Moreover, a downstream cluster collection method of high sensitivity has been developed for detecting a small amount of clusters formed under deposition conditions of Rα < 0.01.
The Correlation of Adhesion Strength with Barrier Structure in Cu Metallization
Authors: Sekiguchi A. , Koike J. , Ueoka K. , Ye J. , Okamura H. , Otsuka N. , Ogawa S. , Maruyama K. 
Published: June 2019

AbstractAdhesion strength in sputter-deposited Cu thin films on various types of barrier layers was investigated by scratch test. The barrier layers were Ta1-xNx with varied nitrogen concentration of 0, 0.2, 0.3, and 0.5. Microstructure observation by TEM indicated that each layer consists of mixed phases of β;-Ta, bcc-TaN0.1, hexagonal-TaN, and fcc-TaN, depending on the nitrogen concentration. A sulfur- containing amorphous phase was also present discontinuously at the Cu/barrier interfaces in all samples. Scratch test showed that delamination occurred at the Cu/barrier interface and that the overall adhesion strength increased with increasing the nitrogen concentration. A good correlation was found between the measured adhesion strength and the composing phases in the barrier layer.
Properties and Barrier Material Interactions of Electroless Copper used for Seed Enhancement
Authors: Witt C. , Pfeifer K. 
Published: June 2019

AbstractThe conventionally used sequence for copper damascene metallization consists of barrier deposition, physical vapor deposition (PVD) Cu seed and electroplated copper. Due to the limited step coverage of PVD copper, the extendibility of this sequence to feature dimensions below 90 nm is at risk. To reduce the risk of pinch-off of very small features, the PVD layer thickness will be reduced well below 100 nm, the drawback being poor seed coverage at the bottom of the features. Void free fill by electroplating is hence at risk by both pinch-off and discontinuous seed coverage (3-5). In this paper, the use of a conformal metal deposition method, electroless copper, to enhance PVD seed layers as thin as 10 nm is presented. It is demonstrated that sparse, discontinuous copper films provide a catalytic surface for electroless copper deposition. With electroless copper, void-free copper fill of 12.5 aspect ratio (AR) trenches (70 nm width) and 8.3 AR vias is achieved. Furthermore, 6 nm thin electroless copper films were integrated in a dual damascene process and electrically characterized. A yield of approximately 85% was achieved on via chains (360000 links, 0.25 by 1.1 μm vias), with 10 nm PVD seed. This was comparable to the yield when using 100 nm PVD seed. Hydrogen, generated as a byproduct during the electroless copper ion reduction, was found in the copper deposits as well as in the barrier films underneath. In some cases, spontaneous blistering in the plated copper film was observed, and is believed to be due to hydrogen incorporation. The interaction of electroless copper films with various barrier materials (PVD Ta, PVD TaN, CVD TiN(Si) and combinations) is discussed. Electromigration test results presented in this paper indicate that the failure mechanism is not qualitatively different from reference samples with the conventional PVD seed.
Electromigration Study of Cu Dual-damascene Interconnects with a CVD MSQ Low k Dielectric
Authors: Lu Xia , Lee Ki-Don , Yoon Sean , Matsuhashi Hideki , Lu Michael , Zhang Kai , Ho Paul S. 
Published: June 2019

AbstractElectromigration reliability in Cu dual-damascene interconnects with a CVD MSQ low k dielectric was investigated. Statistical studies were carried out using the critical length (LC) test structures containing multi-link line/via elements with varying line lengths. EM lifetime characteristics, critical current density-length product (jL)c, and failure mechanisms were discussed and compared with Cu/oxide structures. Our results suggested that the diffusion at the cap layer interface was the dominant mechanism for EM mass transport. The confinement effect, in terms of an effective modulus B, can be used to account for the shorter EM lifetime and smaller critical current density-length product (jL)c observed for Cu/CVD MSQ low k interconnects. Failure analysis by FIB confirmed the presence of multiple failure modes including voiding at the via bottom, Cu extrusion and delamination at Cu/cap layer interface.
Characterization of CVD TixCyNz Films Deposited as Diffusion Barriers for Cu on Low-k Dielectrics Methylsilsequiazane
Authors: Gau W.C. , Liu P.T. , Chang T.C. , Chen L.J. 
Published: June 2019

AbstractMetal organic chemical vapor deposition (MOCVD) TixCyNz films were deposited by using tetrakis-dimethylamino-titanium (TDMAT) and NH3 as a reaction gas at temperatures from 325 to 400°C with multi-layer Ar/NH3 plasma treatment. Effects of annealing and Ar/NH3 plasma treatment on the microstructure, composition, and electrical properties of TixCyNz films were studied. By multi-layers plasma treatment, the resistivity of TixCyNz barriers decreased from 960 to 548 νΔ–cm and the concentration of oxygen in barrier films are also decreased. The integration of the TixCyNz with low-k methylsilsesquiazane (MSZ) was investigated through Cu/CVD-TixCyNz/SiO2 and Cu/CVD-TixCyNz /MSZ capacitors after being annealed in furnace at temperatures from 500 to 800°C. With thermal annealing in N2 ambient for 30 min, Cu/CVD-TixCyNz/ MSZ structure remains metallurgically stable up to 700°C.