Jelle Demeulemeester

Pt redistribution during Ni(Pt) silicide formation

We report on a real-time Rutherford backscattering spectrometry study of the erratic redistribution of Pt during Ni silicide formation in a solid phase reaction. The inhomogeneous Pt redistribution in Ni(Pt)Si films is a consequence of the low solubility of Pt in Ni2Si compared to NiSi and the limited mobility of Pt in NiSi. Pt further acts as a diffusion barrier and resides in the Ni2Si grain boundaries, significantly slowing down the Ni2Si and NiSi growth kinetics. Moreover, the observed incorporation of a large amount of Pt in the NiSi seeds indicates that Pt plays a major role in selecting the crystallographic orientation of these seeds and thus in the texture of the resulting Ni1−xPtxSi film.

The influence of Pt redistribution on Ni1−xPtxSi growth properties

We have studied the influence of Pt on the growth of Ni silicide thin films by examining the Pt redistribution during silicide growth. Three different initial Pt configurations were investigated, i.e., a Pt alloy (Ni+Pt/⟨Si⟩), a Pt capping layer (Pt/Ni/⟨Si⟩) and a Pt interlayer (Ni/Pt/⟨Si⟩), all containing 7 at. % Pt relative to the Ni content. The Pt redistribution was probed using in situ real-time Rutherford backscattering spectrometry (RBS) whereas the phase sequence was monitored during the solid phase reaction (SPR) using in situ real-time x-ray diffraction. We found that the capping layer and alloy exhibit a SPR comparable to the pure Ni/⟨Si⟩ system, whereas Pt added as an interlayer has a much more drastic influence on the Ni silicide phase sequence. Nevertheless, for all initial sample configurations, Pt redistributes in an erratic way. This phenomenon can be assigned to the low solubility of Pt in Ni2Si compared to NiSi and the high mobility of Pt in Ni2Si compared to pure Ni. Real-time RBS furt...

Nucleation and diffusion during growth of ternary Co1−xNixSi2 thin films studied by complementary techniques in real time

The growth kinetics of ternary Co1−xNixSi2 thin films was studied in real time. The “Kissinger” method was applied to the results of ramped sheet resistance measurements to extract the apparent activation energy for the growth process. By simultaneously acquiring sheet resistance, x-ray diffraction and laser light scattering data on one hand and combining resistance measurements and Rutherford backscattering spectrometry on the other hand, we could distinguish between the initial, nucleation controlled thin film growth, and the subsequent diffusion controlled growth. The apparent activation energy for the initial growth decreases with increasing Ni concentration as a result of a lower nucleation barrier for the ternary disilicide. The markedly different microstructure of the ternary Co1−xNixSi2 films with respect to pure CoSi2 layers lies at the origin of a lower activation energy for the diffusion controlled growth of the ternary films. Despite the low activation energy, these films grow at a much slower...

Simultaneous real-time x-ray diffraction spectroscopy, Rutherford backscattering spectrometry, and sheet resistance measurements to study thin film growth kinetics by Kissinger plots

When the Kissinger method is used to investigate thin film growth kinetics, activation energies obtained are often significantly higher than those of Arrhenius plots based on isothermal studies. The reason for the higher activation energies is related to the sensitivity of the Kissinger analysis to nucleation effects. In fact, this often undesirable effect opens the possibility of studying nucleation barriers in a semiquantitative way. Furthermore, we show that these nucleation effects can be filtered out by a more careful application of the Kissinger method, and activation energies that are consistent with Arrhenius plots are then obtained.

(Invited) Assessment of Ge1-xSnx Alloys for Strained Ge CMOS Devices

Strained Ge CMOS Devices S. Takeuchi, Y. Shimura, T. Nishimura, B. Vincent, G. Eneman, T. Clarysse, J. Demeulemeester, K. Temst, A. Vantomme, J. Dekoster, M. Caymax, R. Loo, O. Nakatsuka, A. Sakai, and S. Zaima Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan Covalent Materials Co., Ltd., Higashikou, Seirou-machi, Kitakanbara-gun, Niigata 957-0197, Japan Imec, Kapeldreef 75, B-3001 Leuven, Belgium Instituut voor Kernen Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531, Japan

On the growth kinetics of Ni(Pt) silicide thin films

We report on the effect of Pt on the growth kinetics of δ-Ni2Si and Ni1−xPtxSi thin films formed by solid phase reaction of a Ni(Pt) alloyed thin film on Si(100). The study was performed by real-time Rutherford backscattering spectrometry examining the silicide growth rates for initial Pt concentrations of 0, 1, 3, 7, and 10 at. % relative to the Ni content. Pt was found to exert a drastic effect on the growth kinetics of both phases. δ-Ni2Si growth is slowed down tremendously, which results in the simultaneous growth of this phase with Ni1−xPtxSi. Activation energies extracted for the Ni1−xPtxSi growth process exhibit an increase from Ea = 1.35 ± 0.06 eV for binary NiSi to Ea = 2.7 ± 0.2 eV for Ni1−xPtxSi with an initial Pt concentration of 3 at. %. Further increasing the Pt content to 10 at. % merely increases the activation energy for Ni1−xPtxSi growth to Ea = 3.1 ± 0.5 eV.

Sn diffusion during Ni germanide growth on Ge1-xSnx

We report on the redistribution of Sn during Ni germanide formation on Ge1–xSnx/〈Ge(100)〉 and its influence on the thin film growth and properties. These results show that the reaction involves the formation of Ni5Ge3 and NiGe. Sn redistributes homogenously in both phases, in which the Sn/Ge ratio retains the ratio of the as-deposited Ge1–xSnx film. Sn continues to diffuse after full NiGe formation and segregates in two regions: (1) at the interface between the germanide and Ge1–xSnx and (2) at the surface, which has major implications for the thin film and contact properties.

Artificial neural networks applied to the analysis of synchrotron nuclear resonant scattering data

The capabilities of artificial neural networks (ANNs) have been investigated for the analysis of nuclear resonant scattering (NRS) data obtained at a synchrotron source. The major advantage of ANNs over conventional analysis methods is that, after an initial training phase, the analysis is fully automatic and practically instantaneous, which allows for a direct intervention of the experimentalist on-site. This is particularly interesting for NRS experiments, where large amounts of data are obtained in very short time intervals and where the conventional analysis method may become quite time-consuming and complicated. To test the capability of ANNs for the automation of the NRS data analysis, a neural network was trained and applied to the specific case of an Fe/Cr multilayer. It was shown how the hyperfine field parameters of the system could be extracted from the experimental NRS spectra. The reliability and accuracy of the ANN was verified by comparing the output of the network with the results obtained by conventional data analysis.

On the interplay between relaxation, defect formation, and atomic Sn distribution in Ge(1−x)Sn(x) unraveled with atom probe tomography

Ge(1−x)Sn(x) has received a lot of interest for opto-electronic applications and for strain engineering in advanced complementary-metal-oxide-semiconductor technology, because it enables engineering of the band gap and inducing strain in the alloy. To target a reliable technology for mass application in microelectronic devices, the physical problem to be addressed is to unravel the complex relationship between strain relaxation (as induced by the growth of large layer thicknesses or a thermal anneal) and defect formation, and/or stable Sn-cluster formation. In this paper, we study the onset of Sn-cluster formation and its link to strain relaxation using Atom Probe Tomography (APT). To this end, we also propose a modification of the core-linkage [Stephenson et al., Microsc. Microanal. 13, 448 (2007)] cluster analysis method, to overcome the challenges of limited detection efficiency and lateral resolution of APT, and the quantitative assessment for very small clusters (<40 atoms) embedded in a random distr...

(Invited) GeSn Technology: Impact of Sn on Ge CMOS Applications

S. Zaima, O. Nakatsuka, Y. Shimura, S. Takeuchi, B. Vincent, F. Gencarelli, T. Clarysse, J. Demeulemeester, K. Temst, A. Vantomme, M. Caymax, and R. Loo Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan Research Fellow of the Japan Society for the Promotion of Science Covalent Silicon Co., Higashikou, Seirou-machi, Kitakanbara-gun, Niigata 957-0197, Japan imec, Kapeldreef 75, B-3001 Leuven, Belgium Instituut voor Kernen Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium