Papers by Author: K. Opsomer

Abstract: In this study, Co germanide Schottky barrier diodes on n-Ge (100) substrate were fabricated by sputtering metal Co on Ge, followed by annealing in vacuum at 700°C. The influence of annealing time was investigated on both the electrical properties of Co germanide Schottky barrier diodes and on the phase formation on n-Ge (100) substrate. With increasing annealing times growing or transformation of germanide entities occurs leading to reduction of the trap concentration and therefore the leakage current.

Abstract: In this paper, the deep levels occurring in Fe- or Co-germanide Schottky barriers on ntype Ge have been studied by Deep Level Transient Spectroscopy (DLTS). As is shown, no traps have been found for germanidation temperatures up to 500 oC, suggesting that in both cases no marked metal in-diffusion takes place during the Rapid Thermal Annealing (RTA) step. Deep acceptor states in the upper half of the Ge band gap and belonging to substitutional Co and Fe can be detected by DLTS only at higher RTA temperatures (TRTA). For the highest TRTA, deep levels belonging to other metal contaminants (Cu) have been observed as well. Simultaneously, the reverse current of the Schottky barriers increases with TRTA, while the barrier height is also strongly affected.

Abstract: Nickel monosilicide (NiSi) is a key material in microelectronics and its thermomechanical properties play an important role in determining the stress/strain field generated in a transistor structure. The Coefficient of Thermal Expansion (CTE) is of particular importance in the determination of such a field. As NiSi is used in microelectronics in its polycrystalline form, it becomes of particular interest to study the thermomechanical behaviour of the NiSi aggregate, considered as a unique macroscopic body. The grain orientation of a 120 nm polycrystalline NiSi film grown on single crystal silicon has been studied by means of electron diffraction, and the evaluation of the CTE tensor of the film in the wafer reference frame has been performed by weighted averaging the single grain contributions. The results clearly show the importance of orientation distribution in determining the value of the equivalent coefficient of thermal expansion of the aggregate.