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In this work, we compare the results of different Cliff–Lorimer (Cliff & Lorimer 1975) based methods in the case of a quantitative energy dispersive spectrometry investigation of light elements in ternary C–O–Si thin films. To determine the Cliff–Lorimer (C–L) k-factors, we fabricated, by focused ion beam, a standard consisting of a wedge lamella with a truncated tip, composed of two parallel SiO2 and 4H-SiC stripes. In 4H-SiC, it was not possible to obtain reliable k-factors from standard extrapolation methods owing to the strong CK-photon absorption. To overcome this problem, an extrapolation method exploiting the shape of the truncated tip of the lamella is proposed herein. The k-factors thus determined, were then used in an application of the C–L quantification procedure to a defect found at the SiO2/4H-SiC interface in the channel region of a metal-oxide field-effect-transistor device. As in this procedure, the sample thickness is required, a method to determine this quantity from the averaged and normalized scanning transmission electron microscopy intensity is also detailed. Monte Carlo simulations were used to investigate the discrepancy between experimental and theoretical k-factors and to bridge the gap between the k-factor and the Watanabe and Williams ζ-factor methods (Watanabe & Williams, 2006).

In this paper the electrical and structural characteristics of n-MOSFETs fabricated on 4H SiC with a process based on nitrogen (N) implantation in the channel region before the growth of the gate oxide are reported for low (5x1018 cm-3) and high (6x1019 cm-3) N concentration at the SiO2/SiC interface. The electron mobility and the free carrier concentration in the MOSFET channel were evaluated by Hall effect measurement. The MOSFETs with the higher N concentration had the best electrical characteristics in terms of threshold voltage and field effect mobility, in spite of a lowering of the electron mobility in the channel. The latter is a negative drawback of the fabrication process that probably can be ascribed to an incomplete recovery of the implantation damage or to a high density of interstitial N atoms present in the channel region. In fact, the MOSFETs with the superior electrical performances were fabricated with the higher N+ dose and the shorter thermal oxidation time. However, no evidence of extended defects, clusters or nano-particles in SiC at the interface with the gate oxide was found in every SiC MOSFETs devices observed by electron transmission microscopy

A previously developed Monte Carlo code has been extended to the X-ray microanalysis in a (scanning) transmission electron microscope of plan sections, consisting of bilayers and triple layers. To test the validity of this method for quantification purposes, a commercially available NiOx (x ∼ 1) thin film, deposited on a carbon layer, has been chosen. The composition and thickness of the NiO film and the thickness of the C support layer are obtained by fitting to the three X-ray intensity ratios I(NiK)/I(OK), I(NiK)/I(CK), and I(OK)/I(CK). Moreover, it has been investigated to what extent the resulting film composition is affected by the presence of a contaminating carbon film at the sample surface. To this end, the sample has been analyzed both in the (recommended) “grid downward” geometry and in the upside/down (“grid upward”) situation. It is found that a carbon contaminating film of few tens of nanometers must be assumed in both cases, in addition to the C support film. Consequently, assuming the proper C/NiOx/C stack in the simulations, the Monte Carlo method yields the correct oxygen concentration and thickness of the NiOx film.

A technology computer aided design homemade tool, IMPACT, is described. The mechanical models and the numerical implementation are presented. Details are given about the methodology to calibrate and validate the implementation. This tool is used for the analysis of the processing of a micromachined cantilever. The originality of the study lies in (i) the capability to simulate almost all the sources of stress taking into account the complex rheological behaviours of the materials, (ii) the experimental determination of the mechanical properties of various thin film materials, and (iii) the validation of the calculations by direct comparisons with the measured deformations of the cantilever.

Test structures consisting of shallow trench isolation (STI) structures are fabricated using advanced silicon (Si) technology. Different process parameters and geometrical features are implemented to investigate the residual mechanical stress in the structures. A technology computer aided design homemade tool, IMPACT, is upgraded and optimized to yield strain fields in deep submicron complementary metal–oxide–semiconductor devices. Residual strain in the silicon substrate is measured with micro-Raman spectroscopy (m-RS) and/or convergent beam electron diffraction (CBED) for large (25 micron) and medium size (2 micron), while only CBED is used for deep submicron STI (0.22 micron). We propose a methodology combining CBED and technology computer aided design (TCAD) with m-RS to assess the accuracy of the CBED measurements and TCAD calculations on the widest structures. The method is extended to measure (by CBED) and calculate (by TCAD) the strain tensor in the smallest structures, out of the reach of the m-RS technique. The capability of determining, by both measurement and calculation, the strain field distribution in the active regions of deep submicron devices is demonstrated. In particular, it is found that for these structures an elastoplastic model for Si relaxation must be assumed.

The use of TiSi 2 layers as ohmic contacts in complementary MOS (CMOS) devices is expected to introduce large distortions in the underlying silicon which may degrade the device performances. In this work, the TEM technique known as convergent beam electron diffraction (CBED) has been employed to map the strain distributions across 〈1 1 0〉 cross-sectional specimens of sub-quarter-micron CMOS structures. Different experimental set-ups in terms of energy filtering, liquid nitrogen cooling and zone axis have been explored and compared to each other by using three differently equipped microscopes. The strain induced on silicon by TiSi 2 layers has then been investigated, quantified and compared with that due to the presence of an oxide isolation trench. Also, the effects of depositing a TiN capping layer on TiSi 2 have been analysed. Our results show that its presence results in a more tensile strain without altering the strain distribution trend.

In this work we present some recent results concerning the α-particles irradiation of Si1−yCy alloy epitaxially grown on silicon. The study of the damage process is interesting because of the extensive use of backscattering technique as a tool of characterisation of this kind of materials and because of the possibility of adding information about the transformations that this metastable material undergoes. We point out that the irradiation damage process causes a change in the material structure different from that due to the thermal treatments. The irradiation damage occurs at a rate much higher than in Si, however it involves only a silicon atom fraction that appears to be proportional to the substitutional carbon content.

The Large Angle Convergent Beam Electron Diffraction (LACBED) technique has been applied to determination of the tetragonal mismatch in coherent Si/Si1−xGex/Si heterostructures. Two-dimensional (2D) dynamical simulation of the LACBED patterns has been performed and compared with the corresponding experimental ones. A good agreement is found in the whole simulated area, particularly as regards the splitting of the Bragg contours, due to the strain field present in the TEM cross-sections.

MMoO 4 /SiO 2 composites (M=Ni or Co) were prepared by a sol–gel procedure involving Si(OMe) 4 , M(NO 3 ) 2 and (NH 4 ) 6 Mo 7 O 24 as starting materials. The dried gels were treated at increasing temperatures until crystalline grains of MMoO 4 highly dispersed in the amorphous silica matrix were formed (675°C). They were evidenced by XRD and TEM measurements. Beside supporting the MMoO 4 mixed oxide, the silica xerogel appears to play the important role of stabilizing the β-phase of nickel molybdate, which otherwise would turn into the α-phase at room temperature. The catalytic activity of the β-NiMoO 4 /SiO 2 composite in the oxidative dehydrogenation of isobutane was compared with related systems containing the metastable β-molybdate.

X-ray microanalysis, when performed in an analytical electron microscope (AEM) equipped with an energy dispersive spectrometer (EDS), is a powerful technique for determining chemical composition at high spatial resolution.The basic aspects of the generation and detection of X-rays will be reviewed and the problem of quantification of thin films (composition and thickness) will be discussed.

The relaxation which occurs along the thinning direction of transmission electron microscopy (TEM) cross-sections of heterostructures is still poorly known. This has so far prevented the accurate determination of the corresponding bulk mismatch values from convergent-beam electron diffraction (CBED) patterns. In this paper it is demonstrated that, by using elasticity theory, it is possible to deduce a simple relationship for (001) heterostructures which relates the latice mismatches along the different crystallographic directions of the TEM specimen, as deduced from a single CBED pattern, to the bulk value. Both 〈001〉 and 〈110〉 orientations of the TEM cross-sections are considered. However, to obtain accurate results, the validity of the kinematical approach used to deduce mismatches from high-order Laue zone line patterns must be critically checked; it depends on the crystallographic projection, on the beam voltage and, in the case of Si1−xGex heterostructures, on the Ge concentration. It is fou...

The behavior of silicon slices very heavily implanted (1.5\ifmmode\times\else\texttimes\fi{}${10}^{17}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$) with phosphorus was investigated by transmission electron microscopy and secondary neutral mass spectrometry (SNMS) after annealing at 800, 850, 900, and 1000 \ifmmode^\circ\else\textdegree\fi{}C. Precipitation of large monoclinic, and partially orthorhombic, SiP particles takes place in the most heavily doped region. From the shape of the SNMS profiles in the dissolution stage of these precipitates, we determined the concentration ${\mathit{C}}_{\mathrm{sat}}$ of P in equilibrium with the conjugate phase: ${\mathit{C}}_{\mathrm{sat}}$=2.45\ifmmode\times\else\texttimes\fi{}${10}^{23}$exp(-0.62/kT) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. This concentration has to be compared with the equilibrium concentration ${\mathit{n}}_{\mathit{e}}$ of the electrically active dopant. To this end, more accurate determinations of ${\mathit{n}}_{\mathit{e}}$ were performed on heavily P-doped polysilicon films. It was found that ${\mathit{n}}_{\mathit{e}}$=1.3\ifmmode\times\else\texttimes\fi{}${10}^{22}$exp(-0.37/kT) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. Hence for T\ensuremath{\gtrsim}750 \ifmmode^\circ\else\textdegree\fi{}C, ${\mathit{C}}_{\mathrm{sat}}$ exceeds ${\mathit{n}}_{\mathit{e}}$ and the concentration (${\mathit{C}}_{\mathrm{sat}}$-${\mathit{n}}_{\mathit{e}}$) of inactive mobile P increases with temperature. The formation and the diffusion behavior of this inactive dopant are in keeping with a preprecipitation phenomenon. \textcopyright{} 1996 The American Physical Society.

The convergent beam electron diffraction (CBED) technique has been applied to determine the lattice strain in Si1−xGex/Si heterostructures and in local isolation structures. Both plan and cross-sections have been investigated by transmission electron microscopy. In the heterostructures, the strain value obtained by CBED along the growth direction ɛCRED is affected by a relaxation induced by the thinning process in a direction normal to the cross-section plane, being generally smaller than the bulk tetragonal value ɛT This effect can be overcome using the large angle CBED technique on plan sections. In addition, in the heterostructures the Ge concentration has been determined by energy dispersive X-ray spectrometry, allowing the pseudomorphicity of the samples to be evaluated. All the values of strain and Ge concentration thus obtained are in good agreement with those deduced from Rutherford backscattering spectrometry. In isolation structures, the CBED technique has been applied to determine the d...

Si1−xGex heterostructures have been grown by molecular beam epitaxy, with nominal compositions of 10 and 15 at %. Analytical electron microscopy, Rutherford backscattering spectrometry and ion channeling have been used in order to determine film thickness, Ge molar fraction and tetragonal distortion. The actual Ge concentrations were found to be smaller than the nominal ones. For all the SiGe films a coherent growth was found, with a small deviation from the perfect tetragonal distortion. The good agreement found between the results obtained by each analytical technique demonstrate that these methods of characterization are powerful tools for the control of the epitaxial layer parameters.

A Monte Carlo code, previously set up to simulate electron energy loss spectra of carbon films on silicon at 100 kV, has been extended to the analysis, at 300 kV, of a Si/SiO 2/ Si structure; the final goal is the determination of the oxygen concentration in SiO x precipitates embedded in a Si matrix. The upgrading of the programme has required the introduction of relativistic kinematics and relativistic corrections to elastic and inelastic cross sections. The Si/SiO 2 /Si samples have been prepared by CVD deposition of a 16 nm thick silicon film onto a silicon wafer covered with a 11 nm thick thermal oxide. The thickness of both films has been checked by transmission electron microscopy on cross sections

The precipitation and dissolution of monoclinic SiAs, in Si samples implanted with 1 and 1.5\ifmmode\times\else\texttimes\fi{}${10}^{17}$ ${\mathrm{As}}^{+}$/${\mathrm{cm}}^{2}$, was followed at 800, 900, and 1050 \ifmmode^\circ\else\textdegree\fi{}C by transmission electron microscopy (TEM) and secondary neutral mass spectrometry. It has been found that the concentration ${\mathit{C}}_{\mathrm{sat}}$ of mobile As, which diffuses after equilibration with the monoclinic SiAs precipitates, is given by ${\mathit{C}}_{\mathrm{sat}}$=1.3\ifmmode\times\else\texttimes\fi{}${10}^{23}$ exp(-0.42/kT) ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$, where kT is in eV. This saturation concentration includes different states of As in equilibrium with the monoclinic phase at the annealing temperatures, namely, (i) the electrically active and (ii) the inactive mobile dopant. The results presented in this paper indicate that the inactive As is in the form of clusters. The link between the clustering phenomenon and the presence of small particles detected by TEM observations is also discussed.

The molecular carbonyl cluster HFeCo3(CO)12(1) affords an ultrafine Fe–Co powder by thermal treatment under inert atmosphere. Several magnetic or magneto–structural transformations have been evidenced by thermomagnetic analysis (TMA) from 20 to 950 °C. Transmission electron microscopy (TEM) investigations on samples treated at an intermediate temperature showed the presence of both mono- and bi-metallic crystallites of nanometric size. The saturation magnetization was found to increase with increasing annealing temperature, while the opposite behaviour was found for coercitivity. A comparison was made with the magnetic properties of the cast FeCo3 alloy.

Backscattering and ion channeling measurements have been carried out on 〈100〉 silicon wafers implanted with a dose of 3×1016 As+/cm2. These samples have been submitted to laser annealing and then to various thermal annealings in the 350–1000 °C temperature range. Three different crystallographic directions, 〈100〉, 〈110〉, and 〈111〉, have been explored. The deactivated As atom displacement with respect to the lattice sites has occurred already by the first stage of electrical deactivation at 350 °C. The average displacement is constant in the considered temperature range and has been found equal to 0.23±0.06 A making an angle of 23±8° with the [100] direction. By comparing this finding with the local atomic As arrangement, deduced from previously reported extended x‐ray absorption fine structure measurements performed on the same samples, new cluster models are presented. These models consist of As2V and As4V clusters during the very early stage of deactivation, and of several As4V clusters grouped together...

The thermal evolution of monoclinic SiAs precipitates at 1050° C in silicon samples implanted with 1 and 1.5×1017 As/cm2 was followed by transmission electron microscopy (TEM) and secondary neutral mass spectrometry (SNMS). These experiments show, for the first time, the coexistence of two different states of As in silicon, i.e., the electrically active and the inactive mobile dopant, in equilibrium with monoclinic SiAs precipitates. Moreover, they provide, for the saturation concentration of As in silicon, which includes both these states, a value of 3×1021 cm−3 at 1050° C.

The tetrahedral heterobimetallic cluster (C 5 H 5 )NiRu 3 H 3 (CO) 9 , 1 , when decomposed on KOH-modified γ-alumina, produces an effective heterogeneous catalyst for ammonia synthesis. Bimetallic particles have been evidenced on the support surface by analytical electron microscopy; their main size is 4.0 nm and their Ni/Ru atomic ratio is practically the same as that of the starting cluster. The treatment of unsupported 1 with alcoholic KOH gives a black, conductive, amorphous alloy powder. In this case, the ultrafine and bimetallic nature of the individual particles was also revealed by analytical TEM investigations.

Silicon wafers have been implanted with As+ ions at an energy of 100 keV and a dose of 1 × 1017 cm−2 and subsequently annealed at 1050°for 15 min. This results in a peak As concentration of 7 × 1021 cm−3, which is far beyond the solid solubility value of arsenic in silicon at this annealing temperature. Rod-like precipitates, dislocations, and small precipitate-like defects have been observed by transmission electron microscopy. From the analysis of several diffraction patterns taken on a number of rod-like particles at different tilt angles, it has been unambiguously found that they have the structure of the monoclinic SiAs compound previously reported in literature. The stoichiometry of the precipitates has been confirmed by x-ray microanalysis. To our knowledge, this is the first time that this SiAs phase is detected in As+-implanted silicon.

Molybdenum silicide is investigated because of its possible application in a self‐aligned process for ultra large scale integration technology. p+/n shallow junctions are fabricated by boron implantation through Mo films or MoSi2 layers and rapid thermal annealing. Both procedures enable us to obtain junctions as shallow as 130 nm with very good electrical characteristics (reverse current density 1 nA/cm2 at −1 V, ideality factor 1.05 and contact resistivity 1×10−6 Ω cm2). The influence of a surface preamorphization with different thicknesses on junction depth and electrical characteristics is reported.

A method to perform nanobeam diffraction (NBD) in a transmission electron microscope with high spatial resolution and low convergence angle is proposed. It is based on the use of a properly fabricated condenser aperture of 1 mu m in diameter, which allows an electron beam about 10 nm in size to be focused on the sample, with a convergence angle in the 0.1 mrad range. Examples of NBD patterns taken in an untilted < 110 > cross section of a silicon device are shown. Their quality is adequate for spot position determination and hence to obtain, in principle, quantitative strain information. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3003581]

Laser‐annealed and further thermally annealed arsenic implanted silicon specimens have been investigated in a range of doses from 1×1016 to 5×1016 As/cm2, with different experimental techniques: electrical measurements, transmission electron microscopy (TEM), double‐crystal x‐ray diffractometry (DCD), and extended x‐ray absorption fine structure analysis (EXAFS). On the as laser‐annealed samples, in the whole range of doses examined, a lattice contraction of the doped layer has been evidenced by DCD, whereas, on the same specimens, EXAFS measurements have shown the presence of a local expansion around substitutional As atoms. The relationship between strain and carrier concentration has been found to be approximately linear and can be described by the presence of a size and an electronic effect, as recently proposed in the literature. The former effect represents the atomic size contribution, while the latter is the strain induced by the variation of the conduction‐band minima due to the doping. After a s...

A method of X-ray microanalysis based on a Monte Carlo code, recently developed to determine simultaneously both the composition and the thickness of thin self-supporting films, has been applied to the analysis of titanium silicide films in a 300 kV transmission electron microscope. The film composition corresponds well to the TiSi 2 phase, as determined from diffraction patterns, whereas its thickness is very close to the one obtained by convergent-beam diffraction in an adjacent silicon region. In addition, the bootstrap method of statistics is applied to evaluate, from the experimental errors, the accuracy of the analytical results.

Summary A method to extract accurate information on the displacement field distribution from split high-order Laue zones lines in a convergent-beam electron diffraction pattern of nanostructures has been developed. Starting from two-dimensional many beam dynamical simulation of HOLZ patterns, we assembled a recursive procedure to reconstruct the displacement field in the investigated regions of the sample, based on the best fit of a parametrized model. This recursive procedure minimizes the differences between simulated and experimental patterns, taken in strained regions, by comparing the corresponding rocking curves of a number of high-order Laue zone reflections. Due to its sensitivity to small displacement variations along the electron beam direction, this method is able to discriminate between different models, and can be also used to map a strain field component in the specimen. We tested this method in a series of experimental convergent-beam electron diffraction patterns, taken in a shallow trench isolation structure. The method presented here is of general validity and, in principle, it can be applied to any sample where not negligible strain gradients along the beam direction are present.

Silicon-germanium thin films have been analyzed by EDS microanalysis in a field emission gun scanning transmission electron microscope (FEG-STEM) equipped with a high angular dark-field detector (STEM/HAADF). Several spectra have been acquired in the same homogeneous area of the cross-sectioned sample by drift-corrected linescan acquisitions. The Ge concentrations and the local film thickness have been obtained by using a previously described Monte Carlo based “two tilt angles” method. Although the concentrations are in excellent agreement with the known values, the resulting confidence intervals are not as good as expected from the precision in beam positioning and tilt angle position and readout offered by our state-of-the-art microscope. The Gaussian shape of the SiKα and GeKα X-ray intensities allows one to use the parametric bootstrap method of statistics, whereby it becomes possible to perform the same quantitative analysis in sample regions of different compositions and thicknesses, but by doing only one measurement at the two angles.

High order Laue zone lines present in the central disk of convergent beam electron diffraction patterns have been used to determine the bulk mismatch in thinned, cross‐sectioned heterostructures, where a relaxation occurs along the thinning direction. The position of these lines is sensitive to lattice parameters along different crystallographic directions, so that information on the residual strain along the growth and the thinning directions can be extracted from a single diffraction pattern. This information has been properly combined using the isotropic elasticity theory to give the bulk mismatch. The results are in good agreement with independently obtained bulk measurements.

Residual stresses can significantly affect the performances of silicon micro-structures. The understanding of the residual stress growth during their processing is of great importance. However, the experimental tracing of the stress at the various stages of the machining is still almost impossible. Quantitative modelling of these problems is the alternative to provide guidelines for the minimization of the residual stresses. In this paper, we describe a technology computer aided design homemade tool, IMPACT. The mechanical models and the numerical implementation are presented. We give details about our methodology to calibrate and validate our implementation. The originality of this study lies in (1) the capability to simulate almost all the sources of stress taking into account of the complex rheological behaviors of the materials, (2) the experimental determination of the mechanical properties of various thin film materials and (3) the validation of the calculations by direct comparisons with measured deformations in the micro-structures.

Convergent beam electron diffraction is a technique available in any modern transmission electron microscope. It allows the determination of the strain tensor in crystals at the nanometer scale. The basic principles of the method and examples of application to microelectronic devices are given.

The electrical deactivation of Sb atoms highly implanted (2 and 5×1016 ions/cm2) in crystalline silicon is studied by the extended x‐ray absorption fine structure (EXAFS) method. By following the evolution of the local atomic environment around the Sb atoms it is shown that the description of the deactivation process must take into account the existence of vacancy complexes, SbV2, in addition to the usual antimony rhombohedric precipitates. These vacancy complexes are already present after laser annealing in the 5×1016 ions/cm2 case. Co‐implantation with boron delays the precipitation of Sb particles, by forming new complexes, SbBV or SbB2, with a Sb atom surrounded by two sites (B and/or vacancy).

The convergent beam electron diffraction technique (CBED) of the transmission electron microscopy (TEM) has been employed to determine the strain distribution along a cutline parallel to the padoxide/Si interface in a 0.80 micron wide recessed-LOCOS structure. The values of the components of the strain tensor so obtained have been compared with those computed by two simulator codes. It has been found that both the LOCOS morphology and the strain distribution deduced from TEM images and TEM/CBED patterns, respectively, were in agreement with the simulation results, if some oxidation-related parameters were modified.

The effect on spatial resolution of the spherical aberration of the objective prefield of a Philips CM30 (S)TEM has been investigated. For this purpose, the lattice mismatch of a 20 nm thick Si-Ge film in a cross-sectioned Si/Si0.9Ge0.1/Si heterostructure has been determined by convergent beam electron diffraction (CBED), performed at 100 kV with a spot size of 20 nm. It has been found that, if the disk of minimum confusion is focused onto the specimen plane, the measurement is not affected by a change in the size of the condenser-2 aperture. Therefore, the mismatch information is contained within the Gaussian part of the electron probe. In strain profile determinations by CBED, this allows one to use higher beam intensities (larger C2-apertures) with improved signal/noise ratios and reduced sample drift due to shorter acquisition times.

The Monte Carlo simulation has been applied to the determination of composition and thickness of thin Si1-x Ge x alloys in cross-sectioned, pseudomorphic Si1-x Ge x /Si heterostructures. The experimental intensity of the SiKα, GeLα and GeKα X-rays have been measured in an analytical electron microscope and ratioed. Two methods have been applied: the ‘2-tilt angle method’, which is based on the convergence of the I(SiKα)/I(GeLα) ratios at two different tilt angles, and the ‘2-ratio method’, which uses the I(SiKα)/I(GeKα) and the I(SiKα)/I(GeLα) ratios at a fixed angle. It is found that both methods give solutions, but not in the whole Ge concentration range investigated (from 5 up to 30 at.%). The best way is to apply the ‘2-tilt angle method’, but using I(SiKα)/I(GeKα) ratios.

An overview is given of transmission electron microscopy techniques to address strain with nm scale spatial resolution. In particular the possibilities and limitations of (large angle) convergent beam electron diffraction ((LA)CBED) and electron diffraction contrast imaging (EDCI) techniques are discussed in detail. It will be shown by a few case studies that unique and quantitative information on local strain distributions can be obtained by the combined use of both (LA)CBED and EDCI in correlation with three dimensional finite element simulations of the strain distributions in the thinned specimen.

Using isotropic elasticity theory it is possible to determine the bulk mismatch in thinned, cross-sectioned heterostructures, where a relaxation occurs along the thinning direction. This is accomplished by measuring, in the central disk of a single Convergent Beam Electron Diffraction (CBED) pattern, the position of the High Order Laue Zone lines, which are sensitive to lattice parameters along different crystallographic directions. The results obtained in both uniform and graded Sil-xGex/Si heterostructures are in good agreement with bulk values deduced from independent techniques.

It is now widely accepted that one of the major issues for the future deep sub-micron integrated circuit (IC) technologies regarding yield, device performance and stability and device and product reliability, is the mechanical stress built up in the layers and substrate. It is therefore important to give a quantitative account of these stresses and this can only be achieved by disposing of reliable, performant (as to spatial resolution) and quantitative techniques for the local stress determination in the substrate, of adequate and dedicated process simulation tools and of sensitive methods to analyse the stress effects on device performance.The only experimental technique presently available which allows the strain field distribution in sub-micron CMOS devices is the convergent beam electron diffraction technique of the transmission electron microscopy. Its sensitivity is of the order of 10-4 and its spatial resolution is of 1 nm if a TEM/FEG is employed.