Wet and Siconi® cleaning sequences for SiGe p-type metal oxide semiconductor channels

• Published in: Microelectronic engineering 2018-02, Vol.187-188, p.84-89
• Main Authors: Raynal, P.E., Loup, V., Vallier, L., Martin, M., Moeyaert, J., Pelissier, B., Rodriguez, Ph, Hartmann, J.M., Besson, P.
• Format: Article
• Language: English
• Subjects: Carbon; Channels; Chemical composition; Cleaning; Contaminants; Deionization; Efficiency; Epitaxial growth; Field effect transistors; Germanium oxides; Hafnium; MOSFETs; P-type semiconductors; Physics; Queues; Semiconductor devices; Semiconductors; SiGe Siconi® preclean WET clean Grazing XPS Source drain epitaxy; Silicon; Silicon dioxide; Silicon germanides; Silicon oxides; Surface preparation; Transistors
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2017.12.003

The low temperature integration of new materials (such as SiGe channels for the holes) is mandatory in advanced metal oxide semiconductor field effect transistors (i.e. in 14nm technology node devices and beyond). In this paper, we have investigated the removal of SiGe oxides prior to Selective epitaxial Growth of Si or SiGe:B in Sources/Drains regions. A very efficient removal of contaminants (C, F, O…) is mandatory if the H2 bake that precedes epitaxy is removed because of thermal budget constraints. As germanium is very reactive in the air, in-situ surface preparation schemes (conducted for instance in a Siconi® chamber) might be useful on SiGe surfaces. This way, the queue-time issues associated with “HF-Last” (HF/HCl follow by deionization water rinse) processes in single wafer wet cleaning tools are avoided. Germanium-rich SiGe layers (Si0.6Ge0.4) were used to characterize the native oxide removal efficiency of “HF-Last” and Siconi® processes. Then, a new surface preparation strategy was developed based on i) a wet chemical oxide formation followed by ii) a standard Siconi® process whose efficiency towards SiO2 has conclusively been demonstrated. Parallel Angle Resolved X-ray Photoelectron Spectroscopy was used to study the chemical composition of the native or chemical oxide and evaluate the efficiency of that treatment on carbon, germanium oxide and silicon oxide. [Display omitted] •The high reactivity of SiGe surfaces to air-reoxidation limits the performances of HF-based wet treatments before epitaxy•in-situ Siconi preparations do not allow C contamination removal•Cleaning Sequences based on the combination of wet and an in-situ dry treatment are proposed as pre epi surface preparations•SC1 cleanings can be used in the wet step of the sequence