| AVS 63rd International Symposium & Exhibition | |
| Novel Trends in Synchrotron and FEL-Based Analysis Focus Topic | Tuesday Sessions |
| Session SA+AS+BI+MI-TuA |
| Session: | Synchrotron and XFEL Advances for Biological Systems (2:20-3:40 pm)/Synchrotron Radiation at the Frontiers of Device Technology (4:20-6:20 pm) |
| Presenter: | Thierry Conard, IMEC, Belgium |
| Authors: | T. Conard, IMEC, Belgium V. Spampinato, IMEC, Belgium L. Nyns, IMEC, Belgium S. Sioncke, IMEC, Belgium J.M. Ablett, Synchrotron SOLEIL- Ligne GALAXIES, France W. Vandervorst, IMEC, KU Leuven, Belgium |
| Correspondent: | Click to Email |
The use of InGaAs as a high carrier mobility CMOS-channel material requires a proper electrical passivation of its interface with the gate dielectric. One of the passivation schemes investigated involves the use of Sulphur. In this work, high-k stacks on Sulphur passivated InGaAs substrates involving both Al2O3 and HfO2 are investigated. A major question related to the use of Sulphur relates to the chemical states at the interfaces. XPS is traditionally an important technique for interface analysis but faces several challenges in its application to the above mentioned stacks. First, due to the large number of elements involved, numerous peak interferences are present limiting the choice of useful photoemission peaks. Second, relevant stacks have total thicknesses of the order of 4 nm, which lead to very low intensities , certainly for minority elements like Sulfur. In this work, we discuss the impact of the H2S passivation temperature as well as the use of TMA pre-pulses in the growth of Al2O3. We show that the Sulphur bind to In but that no As-S or Ga-S bonds could be detected. The use of a TMA pre-pulse after surface passivation leads to a reduction of the amount of Sulphur present at the interface and likely increases the amount of In-O bonds. Higher temperature H2S passivation leads to a reduction of the amount of Sulphur at the surface.
We also observe that the presence/absence of S at the interface, as well as the presence of the Al2O3 buffer, which has a major impact on the relative peak position in the spectra between the substrate and the overlayer. This will be compared with the electrical characteristics of the stacks.
Finally, we show that using the Sessa software, full quantification of the stack can be obtained under the condition that all instrumental parameters are correctly taken into account.