Nucleation, Hydroxylation, and Crystallization Effects in ALD SrO

作者：Wang Han; Jiang Xiaoqiang; Fu Kan; Willis Brian G^*

来源：Journal of Physical Chemistry C, 2013, 117(22): 11578-11583.

DOI：10.1021/jp3126472

The atomic layer deposition (ALD) of SrO thin films from strontium bis(tri(isopropyl)cyclopentadienyl) (Sr((C5Pr3H2)-Pr-i)(2)) and H2O was studied by using in situ real-time spectroscopic ellipsometry (RTSE), ex situ X-ray photoelectron spectroscopy (XPS), and grazing-incidence X-ray diffraction (GI-XRD). It is found that with H2O as the oxidant, deposition temperature strongly affects film composition. At 250 degrees C films consist of polycrystalline Sr(OH)(2) while at 350 degrees C polycrystalline SrO is observed. The growth per cycle (GPC) is found to be sensitive not only to the crystalline phase (Sr(OH)(2) vs SrO) but also the crystalline orientation. For films prepared at high temperatures and subsequently cooled for continued growth at lower temperatures, an unusual transient growth per cycle (GPC) enhancement of over 160% for more than 100 cycles is observed. The enhancement is found to be related to the orientation of the Sr(OH)(2) phase, which is influenced by the underlying crystal texture of the substrate. Substrate nucleation effects were also observed for growth on SiO2/Si substrates. A Sr silicate layer with stoichiometry close to Sr2SiO4 forms spontaneously during ALD growth and transiently enhances the GPC.

• 出版日期2013-6-6