Center for CompleX Analysis

We have investigated silicon-germanium (SiGe) line structures employing metallic apertures in combination with Raman spectroscopy to obtain high-spatial strain resolution below the diffraction limit. The apertures were cut into specifically shaped electrochemically etched tungsten tips, which were adjusted within the Raman laser beam on the sample surface by a tuning fork atomic force microscope. With this setup, line structures on patterned SiGe films with a center-to-center distance down to 200 nm were resolved in the Raman scans, evidently indicating a resolution clearly below the far-field Raman resolution of about 600 nm for the used instrument. This setup allows improved local strain analysis by Raman spectroscopy and shows potential for further near-field Raman applications.

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 8C 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 Co Ni Si 0.95 0.05 2 was determined. The temperatures for phase formation and phase transitions are significantly lowered on polycrystalline Silicon substrates. 

For Ni silicidation a lamp based anneal, a furnace anneal and a heater based anneal have been used. Ni silicidation on unstructured Si wafers is characterized by means of sheet resistance, XRD and AES. In the second part of this paper the characterization is extended to product wafers using sheet resistance measurements, transistor performance and product yield to investigate the suitability of the different techniques and processes. We will show that all of the above techniques are suitable for NiSi formation if the thermal budget of the 1st anneal step is sufficient to react enough Ni to Ni rich silicide phases or NiSi. A 2nd anneal step after sequential Ni strip has been found to be of minor importance as the backend processing will finish the NiSi formation in case of Nickel rich phases being left after the Ni 1st anneal step. In the direct comparison of NiSi vs. CoSi the former showed equivalent or better yield and performance.

Raman intensity enhancement induced by nanoprobes (metal particles and metallised tips) approached to a strained silicon sample surface is reported. With silver nanoparticles deposited onto a silicon surface, high enhancements in the vicinity of particles were ...

In this paper, the influence of the formation history of a thin Ni 1-x Pt x :Si film on its thermal stability is investigated. Film degradation manifests itself as a transformation of the continuous film into physically separated islands, resulting in a sheet resistance increase. Higher silicide peak formation temperatures were observed to result in a reduced thermal stability. As a result an improved silicide thermal stability is demonstrated for conductive heating as compared to laser/flash msec anneal. This improved thermal stability is discussed in terms of stress, grain size and Pt distribution. The observed thermal stability differences can be explained in terms of the residual stress in the film.