The role of C and N dopants incorporation in phase change materials

Phase change memory (PCM) technology is considered to be among the most promising alternatives to conventional technologies in embedded memories [1]. To allow operation at relatively high temperatures in embedded applications, it is crucial to improve the stability of the amorphous phase. Carbon and nitrogen doping have been shown to significantly increase the crystallization temperature [1-3]. Moreover, the high RESET current requirement [2], which is a limit to the scalability of GeTe and GST, can be reduced by the incorporation of a dopant element [4]. In this presentation we focus on correlating experimental results and ab initio simulations to understand the effect of C and N incorporation in GeTe and GST PCM devices. Understanding the effect of dopants on the change of electronic properties and the mechanisms of the phase transformation requires analysis of the local order and structure of the amorphous to crystalline phases. In this context, we demonstrate that carbon and nitrogen deeply affects the structure and the dynamical properties of the amorphous phase of GeTe. In particular, the inclusion of N and C dopant elements in GeTe has a drastic effect on the vibrational modes of GeTe therefore improving the stability of the glass. This effect goes with an increased mechanical rigidity explaining why these doped GeTe compounds have a higher crystallization temperature than the undoped ones. Finally we will explore, mainly by FTIR and XRD measurements, the effect of C and N dopants during the annealing of amorphous PCMaterials towards their crystalline phases. These results will be discussed in order to understand the origin of the differences of the doped PCMaterials amorphous phase stability (data retention) observed between full sheet materials and the materials integrated in PCM devices. [1] A. Fantini et al., 2010 IEEE International Electron Devices Meeting (IEDM), 2010, pp. 29.21.21-29.21.24. [2] G. Betti Beneventi et al., Solid-State Electronics, 65-66 (2011) 197-204. [3] V. Sousa et al., EPCOS 2011. [4] Q. Hubert et al., IMW 2012.A.R.C. Themoter

Bioluminescence enhancement through fusion of optical imaging and cinematic video flow

International audienceOptical imaging is an efficient mean to measure biological signal. However, it can suffer from low spatial and temporal resolution while animal deformable displacements could also degrade significantly the localization of the measurements. In this paper, we propose a novel approach to perform fusion of cinematic flow and optical imaging towards enhancement of the biological signal. To this end, fusion is reformulated as a population (all vs. all) registration problem where the two (being spatially aligned) signals are registered in time using the same deformation field. Implicit silhouette and landmark matching are considered for the cinematic images and are combined with global statistical congealing-type measurements of the optical one. The problem is reformulated using a discrete MRF, where optical imaging costs are expressed in singleton (global) potentials, while smoothness constraints as well as cinematic measurements through pair-wise potentials. Promising experimental results demonstrate the potentials of our approach

Work Function Tuning of TixSiyNz Electrodes Using Partial Saturation of Chemisorbing Surface during Pulsing Chemical Vapor Deposition

International audienceIn this article, the achievement of TixSiyNz metal gates with tunable work function is demonstrated using partial saturation during pulsing chemical vapor deposition. Thin films were deposited on SiO2 using a pulse sequence with tetrakisdimethyl amido titanium, NH3, and SiH4 precursors. By adjusting the silane pulse, the chemisorption kinetics of silane on the surface is finely tuned to control the composition of TixSiyNz layers. Their effective work functions were measured in metal-oxide-semiconductor capacitors. Results indicate that the effective work function can be accurately monitored in the range of 4.35-4.60 eV by adjusting the silane pulse time

Grain morphology of Cu damascene lines

International audienceThe evolution of the grain structure through annealing of narrow damascene Cu interconnects is important for any further design of highly integrated circuits. Here we present a comprehensive transmission electron microscopy study of damascene lines between 80 nm and 3000 nm wide. Experimental results clearly indicate that morphology evolutions through annealing are strongly influenced by the line width. If the lines are wider than 250 nm a strong connection between the grain structure within the lines and the overburden copper is present at least after sufficient annealing. Once the lines are as small as 80 nm the grain structure within the lines are only weakly connected to the overburden copper grown above. (C) 2009 Elsevier B.V. All rights reserved

Pattern size dependence of grain growth in Cu interconnects

International audienceFine Cu interconnects possess small grains that increase the electrical resistivity of the interconnects. We have performed an extensive transmission electron microscopy study of the grain growth in lines of different sizes, using a recently developed automated indexing method. Different annealing processes were conducted, some with the presence of a top layer that possesses very large grains. Quantification (by crystallographic indexation and mapping) of grain growth in lines as narrow as 80 nm was achieved. We found that grain growth is clearly impeded by geometrical constraints

Modeling and analysis of concentration profiles obtained by in-situ SAXS during cross-flow ultrafiltration of colloids

International audienceConcentration profiles and structural organization of different colloidal suspensions in the vicinity of membrane during ultrasonic-assisted ultrafiltration were previously evidenced from non-destructive, real-time, in-situ SAXS measurements (Jin et al., 2014 [11], Jin et al., 2014 [12]). On the basis of these obtained results, this paper explored by numerical calculation, four key factors of the buildup of concentrated polarization layer in such process (matter accumulation, flow property, permeability and osmotic pressure). Two different kind of systems have been studied: anisotropic Laponite clay particles and soft casein micelle particles. For all the systems and filtration conditions investigated, the results have shown that the level of matter accumulated is directly linked to calculated permeation flux and in accordance with the experimental one. The rheological parameters introduced in the calculations have allowed to deduce the charts of yield stress in the concentrated layers and revealed the important role of suspensions flow properties in the mechanisms of filtration involved near the membrane surface. The measured properties of the accumulated layers have been computed with a recent model based upon permeability and osmotic pressure (Bouchoux et al., 2013 [17]). It has been shown good agreement between modeled and experimental values in permeation flux for all the different systems and filtration explored