1,720,958 research outputs found
Silicon epitaxial film growth on silicon substrate exposed to UV-excited NF3/H-2 gas for native oxide removal
No full textIn situ UV-excited NF3/H-2 gas phase cleaning for native oxide removal and Si epitaxial him growth experiments were carried out in a load-locked reactor equipped with a UV lamp and PEN heater. The effect of composition of NF3/H-2 and UV exposure on the etching characteristics of native oxide and thermal oxide has been studied. Main etching species were identified as F, NFx and HF. Hydrogen added to NF3 gas alleviates silicon surface pitting to result in the very smooth surface. RMS surface roughness was as low as 0.5 Angstrom at the ratio of H-2/NF3 of 3. Analysis of silicon eptaxial film showed the effectiveness of NF3/H-2 gas phase cleaning as the pretreatment process prior to silicon eptaxial him growth. (C) 1999 Published by Elsevier Science B.V. All rights reserved
SENSITIVITY ANALYSIS OF ION-IMPLANTED SILICON-WAFERS AFTER RAPID THERMAL ANNEALING
No full textIn this study, we have investigated sensitivities of the ion implanted silicon wafers processed by rapid thermal annealing (RTA), which can reveal the variation of sheet resistance as a function of annealing temperature as well as implantation parameters. All the wafers were sequentially implanted by the arsenic or phosphorous implantations at 40, 80, and 100 keV with the dose level of 10(14) to 2 x 10(16) ions/cm(2). Rapid thermal annealing was carried out for 10 s by the infrared irradiation at a temperature between 850 and 1150 degrees C in the nitrogen ambient. The activated wafer was characterized by the measurements of the sheet resistance and its uniformity mapping. The values of sensitivities are determined from the curve fitting of the experimental data to the fitting equation of col relation between the sheet resistance and process variables. From the sensitivity values and the deviation of sheet resistance, the optimum process conditions minimizing the effects of straggle in process parameters are obtained. As a result, a strong dependence of the sensitivity on the process variables, especially annealing temperatures and dose levels is also found. From the sensitivity analysis of the 10 s RTA process, the optimum values for the implant dose and annealing temperature are found to be in the range of 10(15) ions/cm(2) and 1050-1100 degrees C, respectively. The sensitivity analysis of sheet resistance will provide valuable data for accurate activation process, offering a guideline for dose monitoring and calibration of ion implantation process
Effects of deposition parameters on composition, structure, resistivity and step coverage of TiN thin films deposited by electron cyclotron resonance plasma-enhanced chemical vapor deposition
No full textTiN thin films of high quality-low impurity content, high crystallinity and low resistivity-were prepared by electron cyclotron resonance (ECR) plasma-enhanced chemical vapor deposition (PECVD) at low temperatures using TiCl4, N-2 and H-2. The effects of gas flow rate, microwave power and temperature on the composition, structure, resistivity and step coverage of the film were studied. Proper control of the H-2 flow rate was important in lowering the resistivity and impurity content of the films and enhancing the step conformality of the deposits. Increases in deposition temperature and in microwave power decreased the deposition rate, resistivity and impurity content of the film. Chlorine was below the detection limit of Auger electron spectroscopy (approximately 0.1 at.%), even at a deposition temperature of 30(310) degrees C. TiN film deposited at 250(400) degrees C showed a resistivity of 96 mu Omega cm and a bottom coverage of 47%. (C) 1997 Elsevier Science S.A.This research was supported by Korean Electronics and Telecommunications Research Institute (ETRI) through the future microelectronics project, 'Studies on Advanced Basic Technology'
Effect of temperature and substrate on the growth behaviors of chemical vapor deposited Al films with dimethylethylamine alane source
No full textAl films were deposited by pyrolysis of dimethylethylamine alane on Si, SiO2 and TiN substrates without a carrier gas. When Al was deposited on Si and SiO2 below 160 degrees C, the incubation time increased from 1 to 11 min as the substrate temperature decreased. But no incubation time was observed on TiN substrate. The nucleation activation energies (E-an) of Al on Si and SiO2 were 0.71 and 0.79 eV, respectively. The growth rate increased as the substrate temperature increased to 160 degrees C and then it decreased with further increase in the substrate temperature. The maximum growth rate of 600 nm/min was observed on TiN substrate. Below 160 degrees C, the growth activation energies (E-act) of Al on Si, SiO2, and TiN were 0.23, 0.34, and 0.1 eV, respectively. The difference in the growth rate and activation energy might be related to substrate conductivity. The texture of Al film was affected by TIN orientation and Al thickness. When the Si substrate was biased at + 100 V, the degree of Al(1 1 1) texture was greatly improved. Al film with low resistivity was denser than that with high resistivity. (C) 1998 Elsevier Science S.A. All rights reserved.This work was partially supported by the Ministry of Education through the Inter-University Semiconductor Research Center (ISRC-96-E-1039)
THIN-FILM TRANSISTORS WITH POLYCRYSTALLINE SILICON PREPARED BY A NEW ANNEALING METHOD
No full textA new annealing method, nucleation by rapid thermal annealing (RTA) and grain growth in furnace annealing, has been developed to obtain high-quality polycrystalline silicon (poly-Si) and to reduce the long annealing time for solid-phase crystallization (SPC) of amorphorus silicon (a-Si) film without a decrease in grain size. Poly-Si thin-film transistors (TFTs) were fabricated using this method and the electrical properties of poly-Si film were evaluated. We obtained higher field effect mobility (25 cm2/(V.s)) and better uniformity (less-than-or-equal-to 5% in 5-inch wafer) than those obtainable by the conventional furnace annealing
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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