Room-temperature deposition of HfNx barrier by radical-assisted surface reaction for through-silicon-via in three-dimensional LSI

We have demonstrated the preparation of a low-temperature-deposited HfNx film as a diffusion barrier applicable to the Cu-through-silicon-via. The sputter deposition of the Hf film without substrate heating and the subsequent radical-assisted surface nitridation reaction successfully forms a thin film of Hf3N2 in a single phase; this so far has not been obtained by reactive sputtering. The obtained phase is actually stable at temperatures up to 500 °C and shows excellent barrier properties comparable to those of the HfN barrier interposed between Cu and SiO2, deposited by reactive sputtering at 350–400 °C.