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International audience; Local mechanical properties of submicron features are of particular interest due to their influence on macroscopic material performance and behaviour. This study is focused on local nanomechanical measurements, based on the latest Atomic Force Microscopy (AFM) mode, where the peak force set point is finely controlled at each pixel. After probe calibration, we evaluate the impact of spring constant of two AFM hand-crafted natural full diamond tips with steel cantilevers, used for mapping. Based on the fast capture of the cantilever deflection at each pixel and real time force curve analysis in the elastic region, AFM local measured contact moduli mappings of the silica beads ('50 GPa) incorporated in an epoxy resin matrix, are compared with those determined using classical instrumented nanoindentation tests. Our analyses show that with the two AFM probes, without local residual deformation, the high moduli of the silica beads measured with this advanced AFM mode are within the standard deviation of the values determined by classical nanoindentation. Lay Description: The knowledge of material properties at the nanometer scale is a key parameter for well understanding and determining the behavior of material at macroscopic scale. In this paper, we compare two methods (an advanced mode and a classical one) based on the analysis of probes in interaction with the surface of studied material. We focus on a latest developed mode for determining local mechanical properties with a very high spatial resolution. For the advanced mode, we also consider two different hand-crafted probes. Our analyses show that with the high spatial resolution advanced mode, local mechanical properties are well determined. We also highlight the impact of the properties of the used probes for this advanced mode. In a final step, the power of the presented investigation lies in the fact that it does not modify the topography of the surface.

In the present work, Film Bulk Acoustic Resonators (FBAR) based on 700 nm-thick LiTaO3 films have been fabricated and characterized. Two orientations of single crystal LiTaO3 thin films have been investigated: (i) $\mathrm{Y}+42^{\circ}$ -cut, in which the longitudinal wave exhibits an electromechanical coupling factor similar to the one of the longitudinal wave in c-axis AlScN; and (ii) X-cut, in which the fast shear wave displays a larger electromechanical coupling coefficient and a lower Temperature Coefficient of Frequency (TCF) than for $\mathrm{Y}+42^{\circ}$ -cut. In both cases, we have demonstrated resonators in the 1–3 GHz range, with electromechanical coupling factors close to respectively 6.6 and 17.4% and quality factors of 230 and 400. Moreover, the X-cut LiTaO3 FBAR displays lower TCF values than those previously reported for LiNbO3 FBAR, with measured temperature coefficients of the resonance and antiresonance frequency of +16 (± 3) and −42 (± 2) ppm/K, respectively. LiTaO3 appears therefore as an appealing candidate for the next generation of wide bandwidth RF filters.

This paper presents a study of the physicochemical and the dielectric characteristics of capacitor structures, with an organosilicate polymer fabricated by initiated chemical vapor deposition as dielectric. The polymer evaluated is the poly(trivinyltrimethylcyclotrisiloxane), and a comparative study on different bottom electrodes was performed. Preliminary results demonstrate that iCVD technique permits the deposition of low roughness, low defect and uniform polymer films, and the dielectric fabricated exhibits a high breakdown field and an original dielectric behaviour, which makes it a prominent candidate for high voltage 3D capacitors.

Directed Self-Assembly (DSA) of Block Copolymer (BCP) is a promising lithography approach to achieve high resolution pattern dimensions. The current chemo-epitaxy process used to induce block copolymer self-alignment is showing today its limitations. This is due to the resolution limitation of conventional lithography technics needed for the guide formation, used to achieve BCP alignment. This paper introduces a new chemo-epitaxy process, named ACE (Arkema-CEA), which is based on sidewall image transfer (SIT) patterning. This process has the great advantage to offer guides of small critical dimension (CD) and pitch that allows the integration of high χ BCP. In this paper, different parameters of the ACE process are investigated (commensurability, spacer CD …) in order to precisely determine the DSA process window defining the best conditions for BCP alignment. Process window with multiplication factor ranging from 2 to 4 are obtained on BCP under investigation.

Actually, thermally induced thin-films dewetting silicon in the silicon-on-insulator is a way to obtain silicon agglomerates with a size and a density fixed by the silicon film thickness. In this paper we report a new method to monitor both the size and the density of the Si agglomerates thanks to the deposition of a carbon-like layer. We show that using a 5-nm thick layer of silicon and additional ≤1-nm carbonated layer; we obtain agglomerates sizes ranging from 35 nm to 60 nm with respectively an agglomerate density ranging from 38 μm −2 to 18 μm −2 . Additionally, for the case of strained silicon films an alternative dewetting mechanism can be induced by monitoring the chemical composition of the sample surface.

Direct metal bonding represents an advanced joining technology that allows vertical stacking with electrical conduction and even heat dissipation. For most metals used as bonding layers, direct bonding when operating at ambient air involves metal oxides. The bonding interface saddles with a trapped oxide layer that might affect electrical conduction and even complete sealing of bonding interface. Titanium especially, because of its high affinity with oxygen, makes oxide free direct bonding very difficult. In the mean time, the remarkable getter effect of Ti matrix allows the dissolution of oxygen during post bonding annealing. In this paper, the bonding limits with regards to the titanium thickness have been investigated. The key role of layer roughness on the bonding quality and energy has been pointed out. A titanium thickness below 10nm appears as a limit for an oxide free bonding.

The bonding of hydrophobic, reconstructed (001) Si surfaces obtained with high temperature H2 processes has been studied with atomic force microscopy, low energy electron diffraction spectroscopy, X-ray reflectivity and bonding energy measurements. Surface reconstruction is shown to strongly affect bonding mechanisms. As a consequence, bonding energies of such surfaces are significantly higher, in the room temperature −500 °C range, than those of “HF-last” surfaces.

Scanning capacitance microscopy (SCM) measurements have been performed on highly doped Si monolayers both in constant-dV and constant-dC modes. The performances of these operating modes have been compared in terms of both signal sensitivity to high doping levels and spatial resolution. A higher sensitivity to boron-doped Si monolayers separated by 30 nm in constant-dC mode is observed. This result is attributed to a higher intrinsic spatial resolution for this latter mode and suggests the further ability of the constant-dC mode to deconvolute the SCM signal to carrier distribution near highly doped layers.

International audience; The use of reconstructed silicon wafers obtained after high temperature annealing under H-2 atmosphere was demonstrated as an efficient way for increasing the bonding energy of silicon hydrophobic bonding (Rauer et al. 2013). Mechanisms occurring in these bondings are the focus of this paper. Si bonding interface closure was analyzed at the nanometer scale using X-Ray Reflectivity and Fourier Transform InfraRed spectroscopy in multiple internal reflexion mode. These two characterization techniques enable one to follow the interface closure taking under consideration mechanical and chemical aspects. We have shown that the terrace morphology and the monohydride surface termination specific to reconstructed Si surfaces both play a role in obtaining an efficient bonding gap closure after annealing at low temperature.

The influence of capping layer composition was examined in accelerated stress-migration performance of AlCu(0.5%) narrow stripe lines. Using resistance monitoring and Scanning Electron Microscopy, we determined that metallisation with bilayer Ti TiN ARC top layer induced more stress voiding than metallisation with single TiN ARC layer. These experimental results are discussed on the basis of a void growth mechanism provided by diffusion at the interface between AlCu and ARC top layer.

Dark current is a drastic specification for any kind of sensor and particularly for imagers dedicated to low light level. We propose here a method for optimizing the InGaAs photodiode properties. An anomalous doping profile feature revealed by scanning capacitance microscopy is counterbalanced by modifying Zn-diffusion process. We analyze the electrical results before further investigation.

In this work, we report a series of Kelvin Force Microscopy (KFM) measurements, suitable to observe the topography and the contact potential difference (CPD) distribution of the following stack: CdTe/CdS/ITO/glass. The sample is prepared by mechanical polishing after cleavage to decrease the roughness. In order to have a better understanding of the charge transport inside the solar cell and to vary the Fermi level pinning effect, different bias are applied to the sample. The CPD variations with different bias on cross‐section in dark condition are presented. We observe the reverse bias widens the CdTe/CdS depletion region. Under illumination, electron and holes are generated near the interface and varies the CPD distribution. Additionally, the chemical composition of each layer has been investigated by nano‐Auger electron spectroscopy (AES). We observe the interdiffusion at the CdTe/CdS interface and determine the composition of the active layers to be CdTe/CdS0.7Te0.3.

In this work, we explore the potential of Kelvin Force Microscopy (KFM) measurements to investigate the lateral charge transport in SiN layers with two different compositions (standard, std, and Silicon rich, Si–rich). The dynamics of the lateral spread of the trapped charge is analyzed with the help of three dimensional numerical device simulations.

The analysis of the Work Function measurements, of different materials, using the Kelvin Force Microscopy technique (KFM) is not trivial. Various artifacts can alter the interpretation of KFM results. Thus a good understanding of experimental conditions effects, involved in a measurement procedure, is essential to provide a reliable interpretation and avoid false conclusions. In this paper, we present an experimental study of the most relevant parameters influencing KFM measurements performed alternatively under air and nitrogen conditions. We investigate the effects of the tip‐sample separation, the tip shape, the relative humidity and the modulation signal applied to the probe. We provide arguments and discussions in order to explain experimentally observed behaviors. We also propose experimental settings and protocols by providing the most convenient conditions for reliable KFM results.

We report the electrical characterization of vertically aligned nano‐objects by Scanning Spreading Resistance Microscopy (SSRM). In this paper, we show that this method is well suited to evaluate the individual electrical properties of carbon nanofibers and of n‐doped silicon nanowires. In the first example, carbon nanofibers exhibit a wide range of resistance which could be explained by the convolution of roughness and of surface oxidation of the TiN layer. An interpretation based on electrical contact resistance model is proposed here to explain this observation. In the second example, n‐doped Si NWs exhibit various range of resistance depending of the Phosphorus/Silicon ratio, which highlighted the control of the doping level.

The high field mobility enhancement in sSOI devices is still unexplained as for now. This work proposes an experimental and theoretical investigation of the physical mechanisms responsible for such a gain. For the first time, we show by atomic force microscopy (AFM) measurements that the surface roughness of sSi is drastically reduced compared to unstrained Si. Introduced into a Kubo-Greenwood model, this improved roughness perfectly reproduces the experimental mobility enhancement at high effective fields (ges1 MV/cm) for a wide range of temperature (50 K-300 K).

Currently, the work‐functions of metal gates are determined using capacitance‐versus‐gate‐voltage measurements of a dedicated MOS capacitor structure. Alternatively, Kelvin Force Microscopy (KFM) is a promising technique which allows the work‐function to be measured with high spatial resolution (

We investigate small artificial quantum dots obtained by geometrically controlled resistive confinement in low mobility silicon-on-insulator nanowires. Addition spectra were recorded at low temperature for various dot areas fixed by lithography. We compare the standard deviation of the addition spectra with theory in the high electron concentration regime. We find that the standard deviation scales as the inverse area of the dot and its absolute value is comparable to the energy spacing of the one particle spectrum., Comment: 4 pages, 5 figures

Grain sizes and crystallographic orientations of Cu were analyzed versus linewidth in damascene Cu interconnects. Pure bamboo lines were not obtained because grain size decreased as linewidth was reduced. Comparison of electromigration results, for wide line Chemical vapor deposition-Cu (3 μm) polycrystalline structure, and narrow lines (0.5 μm) quasi-bamboo structure, provided almost the same activation energy E a ∼0.65 eV, even though the poor (2 0 0) texture has rotated in the film plane for the narrow damascene lines. These results are in agreement with copper diffusion involving surface diffusion. Besides, even with a polycrystalline crystallographic orientation, PVD-Cu samples showed a better activation energy value E a =1.02 eV.

International audience

We have studied the etching properties of silicon-on-insulator (SOI) substrates in recently developed chromium-free solutions containing halogens. We have shown that the presence of halogen compounds X (I−, Br−…) in HF/HNO3/CH3COOH solutions is required for a selective and preferential etching on SOI. The etching rate of such solutions increases with the dissolved halogen concentrations. The chemical reactivity of Si-X (X = Br−, I−..) bonds has been analyzed by X-ray Photoelectron Spectroscopy (XPS), Pseudo-MOS (flatband potential) and Kelvin Force Microscopy (KFM) measurements. A negative shift of flatband potential values is explained by an increasing concentration of halogen compounds in the solution and a substitution of Si-H (F) bonds by Si-X bonds during the reaction. Though Si-X bonds, and more particularly Si-I bonds, have been confirmed only at trace levels using XPS, we believe that the formation of Si-X bonds is supported by a mechanism of surface dipoles. Unexpectedly, no significant change in...

This article reports on the use of atomic force microscopy coupled with a simple wet chemical sample preparation to characterize processes involved in the realization of 0.4 μm metal on silicon contacts. Photolithography and contact etching processes both lead to high aspect ratio topography (≳4). The samples are imaged after a preparation which removes the high aspect ratio and leads to a better image. The main parameters of this new procedure are highlighted in this report, namely contact area for lithography and etching processes and silicon consumption for the etching process. The contact silicidation process is also monitored, and the electrical results are correlated with the silicide thickness formed in the contact.