Dry Hydrogen Plasma Cleaning for Local Epitaxial Growth

An argon/hydrogen discharge plasma was created with a UHV compatible plasma source. This low energy plasma was utilized to remove - in a single step - the native oxide and the hydro- carbons from the wafer surface at substrate temperatures be- tween 100°C and 400°C. During the plasma cleaning procedure, residual gas ions were monitored to elucidate the process chem- istry. To optimize the procedure, the interfaces between the plasma cleaned wafer and the MBE grown epilayer were investi- gated by scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (XTEM). The cleaning process was also applied to patterned silicon substrates. Subsequent local epitaxial growth by MBE at 550°C without the typical high temperature annealing step was achieved, suggesting that the in-situ dry cleaning procedure caused no surface damage.