1,721,383 research outputs found
A linear time algorithm for binary tree sequences transformation using left-arm and right-arm rotations
No full text[[abstract]]In this paper, we consider a transformation on binary trees using new types of rotations. Each of the newly proposed rotations is permitted only at nodes on the left-arm or the right-arm of a tree. Consequently, we develop a linear time algorithm with at most n-1 rotations for converting weight sequences between any two binary trees. In particular, from an analysis of aggregate method for a sequence of rotations, each rotation of the proposed algorithm can be performed in a constant amortized time. Next, we show that a specific directed rooted tree called rotation tree can be constructed using one of the new type rotations. As a by-product, a naive algorithm for enumerating weight sequences of binary trees in lexicographic order can be implemented by traversing the rotation tree. (c) 2006 Elsevier B.V. All rights reserved.[[note]]SC
Mechanism of high density plasma chemical vapor deposition phosphosilicate glass process without in-situ plasma chamber clean
No full text[[abstract]]Plasma chamber dry clean after chemical vapor deposition (CVD) was widely used in the plasma enhanced CVD processes. The effects of the plasma clean periodicity on the deposited film qualities were explored in this research. The variations of the film qualities of high-density plasma phosphosilicate glass (HDP-PSG) were found for consecutive film deposition. The comparisons in the film qualities such as phosphorous concentration, stress, thickness and wet etch rate for successively depositing wafers after plasma chamber dry clean were studied. The phosphorous concentrations were measured using X-ray fluorescence (XRF) method. The consecutively depositing wafers exhibited comparable phosphorous concentrations from the XRF results. The stress of the first three wafers had 10% difference. The first wafer had the most compressive stress. The film thickness of the first wafer was 30-40 nm thicker than that of the third wafer. The film wet etch rate also showed a decreasing trend. The first wafer had 10% higher wet etch rate than the third wafer. The secondary ion mass spectrometry (SIMS) analysis displayed that the first wafer had more uniform phosphorous distribution. The different phosphorus depth profile generated the different wet etch rate performance for the consecutive deposition wafers. These differences in the film qualities were caused by the chamber out-gassing. The residual gas analysis (RGA) was used to monitor the chamber out-gassing. The oxygen and moisture from the chamber out-gassing impacted the HDP-PSG film qualities for no in situ plasma chamber clean. (C) 2004 Elsevier B.V. All rights reserved.[[note]]SC
Effects of wetting ability of plating electrolyte on Cu seed layer for electroplated copper film
No full text[[abstract]]This work examines the impact of the wetting ability of a plating electrolyte on the Cu seed layer on copper electroplating performance. The contact angle of the electrolyte on the Cu seed is highly sensitive to additive decomposition in the electrolyte, as well as being sensitive to Cu seed self-annealing. The contact angle of the electrolyte decreases in the presence of polyethylene glycol (PEG), which forms complexes with chloride ions and is absorbed on the Cu surface during plating. However, the consumption of the additives, particularly that of chloride ions, degrades this adsorption. Additionally, the increase in Cu-seed surface roughness owing to self-annealing also reduces electrolyte wettability, compared to the as-received Cu-seed layer. The poor wettability can be improved with additional rinsing. The x-ray photoelectron spectroscopy (XPS) spectrum demonstrates that the Cu surface was covered with a native cupric-hydroxide layer after rinsing, which was hydrophilic (as in the aqueous-plating bath) and had improved wettability. This study also correlates the contact angle with the trapped defects in the electroplated film, which in turn influence the electrical characteristics of the interconnection. The experimental results show that the poor wettability of the plating electrolyte on the Cu seed significantly influences the fluctuations of the Cu interconnect resistance. This conclusion is valuable in designing Cu damascene processes. (C) 2004 American Vacuum Society.[[note]]SC
Effect of inter-level dielectrics on electromigration in damascene copper interconnect
No full text[[abstract]]The impact of dielectric materials on the reliability of advanced copper (Cu) interconnect is of growing importance. The effect of barrier dielectrics and low-k materials of Inter-Level Dielectric (ILD) on the electromigration (EM) in the line and via-line structure of dual-damascene Cu interconnects was analyzed. The resulting electromigration behavior can then be attributed to Cu barrier layer or low-k dielectrics, depending on the test structure. The SiN barrier layer showed a better electromigration endurance compared to SiC barrier layer for narrow Cu line structure. We had also observed that the carbon-doped oxide (CDO) low-k samples had a higher drift velocity, which results in less electromigration endurance on the via-line structure compared to fluorosilicate glass (FSG). (c) 2005 Elsevier B.V. All rights reserved.[[note]]SC
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
Extraction of effective dielectric constants and the effect of process damage of low-k dielectrics for advanced interconnects
No full text[[abstract]]In this paper, the line-to-line parasitic capacitance of an advanced interconnects with a low-k dielectric (k < 3.0) was extracted by electrical measurement on comb-serpentine structures with various spacing. The empirical values are higher than the prediction from the filed solver, especially in the small geometries. A model was derived based on the damage of low-k dielectric during processing, which causes the increase of the dielectric constant. Then, the effective dielectric constant was evaluated by both simulation and theoretical models. The k value of damage zone was determined from blanket wafer by mercury probe after oxygen plasma treatment. Good agreement was obtained after we modified the simulation structure to include the damage zone. Especially, the concept of low-k damage due to plasma treatment was characterized for the first time. Thus, it is possible to use this model in the future study, such as the porous low-k in 65 nm or even 45 nm generations. (c) 2006 Elsevier B.V All rights reserved.[[note]]SC
Finding a longest common subsequence between a run-length-encoded string and an uncompressed string
No full text[[abstract]]In this paper, we propose an O(min {mN, Mn}) timealgorithm for finding a longest common subsequence of strings X and Y with lengths M and N, respectively, and run-length-encoded lengths in and n, respectively. We propose a new recursive formula for finding a longest common subsequence of Y and X which is in the run-length-encoded format. That is, Y = y(1)y(2) ... y(N) and X = r(1)(l1) r(2)(l2) ... r(m)(1m), where r(i) is the repeated character of run i and l(i) is the number of its repetitions. There are three cases in the proposed recursive formula in which two cases are for r(i) matching y(j). The third case is for r(i) mismatching y(j). We will look specifically at the prior two cases that r(i) matches y(j). To determine which case will be used when r(i) matches y(j), we have to find a specific value which can be obtained by using another of our proposed recursive formulas. (C) 2007 Elsevier Inc. All rights reserved.[[note]]SC
A Note on "An improved upper bound on the queuenumber of the hypercube"
No full text[[abstract]]None[[note]]SC
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