Investigation of atomic vapour deposited TiN/HfO2/SiO2 gate stacks for MOSFET devices

HfO2 films were grown by atomic vapour deposition (AVD) on SiO2/Si (1 0 0) substrates. The positive shift of the flat band voltage of the HfO2 based metal-oxide-silicon (MOS) devices indicates the presence of negative fixed charges with a density of 5 × 1012 cm−2. The interface trap charge density of HfO2/SiO2 stacks can be reduced to 3 × 1011 eV−1 cm−2 near mid gap, by forming gas annealing. The extracted work function of 4.7 eV preferred the use of TiN as metal gate for PMOS transistors. TiN/HfO2/SiO2 gate stacks were integrated into gate-last-formed MOSFET structures. The extracted maximum effective mobility of HfO2 based PMOS transistors is 56 cm2/Vs.