Effect of deposition conditions of poly Si1−xGex films and Ge atoms on the electrical properties of poly Si1−xGex (x=0,0.6)/HfO2 gate stack

The effect of interfacial reactions at the poly Si1−xGex/HfO2 interface on the electrical properties of metal–oxide–semiconductor (MOS) capacitors with a poly Si1−xGex (x=0,0.6)/HfO2 gate stack was investigated relative to the deposition conditions for the poly Si1−xGex films, the Ge content of the poly Si1−xGex films, and the annealing temperatures, by the electrical measurements and x-ray photoelectron spectroscopy. With an increase in hydrogen induced from doping or from deposition gas used during the deposition of poly Si1−xGex (x=0,0.6) films, the accumulation capacitance of the MOS capacitors with a poly Si1−xGex/HfO2 gate stack became anomalous and the leakage current increased significantly, due to the formation of hydroxyl(OH–) ions or the partial reduction of HfO2 at the grain boundary. With an increase in Ge content of the poly Si1−xGex films, silicate formation became dominant at the poly Si1−xGex/HfO2 interface, resulting in a significant decrease in leakage current.