Jochen Rinderknecht

Nano-raman spectroscopy with metallized atomic force microscopy tips on strained silicon structures

In this paper, intensity enhancements of the Raman signal from strained silicon films utilizing the tip enhanced Raman spectroscopy (TERS) effect are reported. Specially shaped metallized atomic force microscopy tips have been prepared by sputter deposition of thin silver films onto sharpened quartz tips and subsequent focused ion beam (FIB) modification. Raman signal enhancements of more than 20%, which are attributed to the strained silicon film of 70nm thickness only, have been obtained due to approaching the TERS tips the laser spot. On samples with patterned trench structures prepared by FIB milling, lateral sample scans have been performed. These scans revealed a resolution of strained silicon lines with center-to-center distances below 250nm, well below the classical optical diffraction limit. Based on an analysis of the stress state in the strained silicon structures, relaxation effects close to the trench edges have been investigated. The described approach of nano-Raman spectroscopy is promising...

Analytics and Metrology of Strained Silicon Structures by Raman and Nano‐Raman Spectroscopy

Straining the active regions in MOSFET devices is one of the key contributors to increase device performance in present and future technology nodes. Since dedicated strain on the transistor level is required with opposite sign for NMOS and PMOS transistors, the need to measure strain locally has become a challenge for analytics and metrology. Raman spectroscopy is capable of obtaining strain information non‐destructively on the sub‐μm scale, and therefore, this technique has been considered for process monitoring. In this paper it will be shown for silicon‐germanium thin films, how both strain and composition can be determined independently by measuring two phonon modes of the film. This technique enables fast measurement of mechanical strain and chemical composition with high accuracy on the μm‐scale. Thus, the micro‐Raman technique is well suited for metrology of strained silicon test structures. Furthermore, it is shown that mechanical strain close to silicon‐germanium structures can be measured with n...

In situ high-temperature synchrotron-radiation diffraction studies of Ni and Co-Ni silicidation processes

Silicidation processes in nanoscale Ni and CoNi (5at.% Ni) layers on different silicon substrates were investigated using X-ray diffraction. The phase formation sequences as well as the formation and transition temperatures between 200 and 750 °C were studied. The impact of different silicon substrates, i.e., polycrystalline Si and (100) oriented Si single-crystal substrates as well as the impact of different species of dopants (As, P) were analysed. The thermal range of the desired low resistance target phases NiSi and Co0.95Ni0.05Si2 was determined. The temperatures for phase formation and phase transitions are significantly lowered on polycrystalline Silicon substrates.

Temperature‐Dependent Stress Measurements at Inlaid Copper Interconnect Lines

The 3‐dimensional stress state of inlaid copper line structures in low‐k dielectrics was measured using synchrotron micro X‐ray diffraction (μ‐XRD) at temperatures between 25°C and 450°C. The barrier layer (Ta or TaN/Ta) had only a low impact on the stress‐temperature behaviour. However, an additional thick SiOxFy capping layer lowered the room temperature stress significantly compared to copper lines with a thin SiCxNy passivation. The effect of this thick capping layer on the slope of the stress‐temperature curve was even more dramatic. Samples without a thick SiOxFy capping layer showed a transition from in‐plane tensile stress to compressive stress between 150°C and 250°C, while samples capped with thick SiOxFy reached this point at higher temperatures or in some cases even stayed tensile up to 400°C. This shift was also dependent on the copper line width. Furthermore, in 4μm wide lines with thick SiOxFy cap the out‐of‐plane stress became more tensile with increasing temperature, leading to a reverse ...

Micro-XRD Stress And Texture Study Of Inlaid Copper Lines - Influence Of ILD, Liner And Etch Stop Layer

The influence of ILD, liner and etch stop layer on the room temperature stress state of copper line test structures was examined by micro‐XRD. Test structures consisted of large arrays of parallel lines with line widths of 0.18 μm and 1.8 μm. All these parameters have an influence on the room temperature stress state, whereas the variation of the liner and the ILD showed the largest effects. The change from a full low‐k stack to a hybrid stack, where SiO2 ILD is use for the ‘via layer’ only and low‐k material for the ‘line layer’ results in completely different parameter dependencies. The relationship between copper microstructure and the resulting stress in copper lines is discussed.