Bombardment-induced silicide formation at rhenium-silicon interfaces studied by XPS and TEM

Reiche, R.; Oswald, Steffen; Hofman, D.; Thomas, Jürgen; Wetzig, K.

doi:10.1007/s002160051448

Cited by 18 publications

(8 citation statements)

References 2 publications

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“…silicide formation during atomic mixing) has already been done by the ion sputtering at the interface under investigation. 22 The only way to minimize damage would be the use of ions of much lower energy from glow discharges or alternative ion guns.…”

Section: Information On Buried Interfaces After Sputter Preparationmentioning

confidence: 99%

Angle‐resolved XPS: a critical evaluation for various applications

Oswald¹,

Zier²,

Reiche³

et al. 2006

Surface & Interface Analysis

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Angle-resolved X-ray photoelectron spectroscopy (ARXPS) is widely accepted as a useful tool for nondestructive in-depth analysis of near surface regions. In the present paper, it is shown for a variety of applications which kind of qualitative and quantitative information can be derived from ARXPS measurements in conjunction with appropriate mathematical modeling. The method is limited mainly by problems arising from contamination, roughness or preparation-induced damage. Furthermore, especially for more complex surface structures, it must be considered that the information content of ARXPS is strongly limited and the calculations have to be supported by other knowledge.

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Section: Information On Buried Interfaces After Sputter Preparationmentioning

confidence: 99%

Angle‐resolved XPS: a critical evaluation for various applications

Oswald¹,

Zier²,

Reiche³

et al. 2006

Surface & Interface Analysis

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“…The sputter rate was about 1 nm min -1 . For sputter-depth profiling ion bombardment-induced silicide formation and intermixing can be expected, as observed in the systems Ta/Si [10] or Re/Si [11]. The resulting set of spectra of our sputter depth profile was again analysed using target factor analysis, which resulted in the same principal components as in the case of the deposition series (Figs.…”

Section: Depth Profilementioning

confidence: 99%

XPS investigations of thin tantalum films on a silicon surface

et al. 2003

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Ultra thin tantalum-based diffusion barriers are of great interest in copper metallisation technology. Even the smallest amounts of copper that diffuse into the active silicon regions on a microprocessor will alter their semiconducting properties thus leading to failure of the device. In the present work Ta films were deposited on silicon by electron beam evaporation and magnetron sputtering. The background of this study is investigation of interface formation, which is expected to have substantial influence on the properties of thin Ta films. All experiments were carried out under UHV conditions. This was necessary because Ta is a very reactive metal and is readily oxidized even at low oxygen partial pressure. The Ta4f peak, as a sensitive indicator of the chemical state, was analysed and compared to that for standard samples. Silicide formation is assumed to occur at the Ta/Si interface.

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“…Investigations of Ta films on Si with sputter depth profiling also confirmed the formation of silicides at the interface Ta/Si [10,16]. However, investigations at other metal/silicon systems showed that silicide formation can also occur as the result of the energy impact from the sputter ions themselves [11,17]. To eliminate this effect, we tried to prepare a non-damaged interface at a 5 nm thick Ta film (here on SiO 2 substrate) by help of low energy ion (Ar + , 1.5 keV) pre-sputtering up to the first Si information occurred in the XP spectra.…”

Section: Xps and Arxps Investigationsmentioning

confidence: 99%

Growth studies of Ta‐based films on Si with STM and XPS

Zahn

Oswald

Fülle

et al. 2007

Phys. Status Solidi (c)

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The aim of the experiments was the characterization of the first stages of film growth on silicon substrates with scanning tunneling microscopy (STM) and angle-resolved X-ray photoelectron spectroscopy (ARXPS). Thin Ta films were deposited in situ by magnetron sputtering onto Si in the thickness range from less than one monolayer up to 10 nm. The results of the experiments show a formation of tantalum silicide at the interface to the substrate. The local current-voltage characteristics obtained by scanning tunneling spectroscopy (STS) measurements show that the first stages of tantalum silicide growth are characterized by island formation. The in situ STM results are in good agreement with those of the ARXPS investigations. 1 Introduction Nowadays, copper is the material for metallic interconnects for the (ultra) large-scale integration in microelectronic devices. Because the copper diffusion into silicon must be minimized, additional diffusion barriers are necessary in such microelectronic devices using copper as wiring material. Up to now tantalum-based thin films are widely used as such barriers [1, 2] and were investigated with different experimental methods [3][4][5]. As a consequence of decreasing barrier thicknesses the knowledge of the first stages of thin film growth on the substrate is necessary [4]. Our experiments on magnetron sputtered ultra thin tantalum-based films complete the knowledge of the tantalum barrier system by results of scanning tunneling microscopy (STM) in comparison with results of X-ray photoelectron spectroscopy (XPS). This leads to additional information about the interface chemistry and the island-like film growth at the silicon substrate, because of the use of high lateral resolved STM also in its spectroscopic I(U)-mode (STS). In measurements with the constant current mode, STM provides hybrid information consisting of both the sample topography and the chemical states on the surface. The tunneling tip exactly follows the sample topography only if the sample surfaces are chemically homogeneous. The spectroscopic STS method in the scanning tunneling microscope also provides information on the sample's electronic surface state. Therefore it is possible to get local information about different chemical compounds on the surface with high lateral resolution using the measurement of the current voltage characteristics in dependence on local position on the sample. Complementary, XPS can deliver large-area information of element composition and chemical bonds at the surfaces. Investigation of surface chemistry is done with the analysis of peak shifts and/or peak shape changes of the photoelectron peaks. By additional use of the angle-resolved XPS (ARXPS) with appropriate model calculations [6,7] one can also get morphological information (film thickness, island growth) which can be compared with the STM/STS results. In this paper we will discuss the results of investigations of tantalum-based ultra thin layers deposited by reactive DC magnetron sputtering. Because of the high reactivi...

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Bombardment-induced silicide formation at rhenium-silicon interfaces studied by XPS and TEM

Cited by 18 publications

References 2 publications

Angle‐resolved XPS: a critical evaluation for various applications

Angle‐resolved XPS: a critical evaluation for various applications

XPS investigations of thin tantalum films on a silicon surface

Growth studies of Ta‐based films on Si with STM and XPS

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