Suppression of silicidation and crystallization by atmosphere controlled annealing for poly-crystalline silicon/ Hf O2 Si O2 Si gate stack structures

The suppression of silicidation and crystallization of gate dielectrics for polycrystalline- SiHf O2 Si O2 Si gate sack structures by controlling annealing ambient has been investigated using photoemission and x-ray absorption spectroscopy. It is found that both silicidation and crystallization are suppressed by a mixture gas (nitrogen and oxygen) annealing. Meanwhile, by nitrogen annealing at the same partial pressure, both silicidation and crystallization occur. In the case of oxygen annealing, silicidation does not occur while only crystallization occurs. From these results, it is concluded that nitrogen and oxygen gases play a role of preventing silicidation and crystallization, respectively.