Ta 2O 5 films were deposited by plasma-enhanced atomic layer deposition (PEALD) and thermal ALD on native oxide surface (SiO x/Si). The properties of as-deposited and forming gas annealed films were examined and qualitatively compared with respect to nanostructural, nanochemical, capacitance-voltage and leakage-current-voltage (J L-V), and oxide breakdown characteristics. Although high-resolution transmission electron microscopy showed structurally sharp Ta 2O 5/SiO x interfaces in forming gas annealed PEALD Ta 2O 5/SiO x/Si stacks, electron energy loss spectroscopy revealed interdiffusion of Ta and Si across this interface, the indiffusion length of Ta being higher than the outdiffusion length of Si. The consequent formation and enhancement of Ta-O-Si bond linkages in thicker Ta 2O 5 films were clearly reflected in the J L- V data. Moreover, the fixed charge density (Q f=5 × 10 11q C/cm -2) was thickness invariant in PEALD Ta 2O 5. For similar PEALD and ALD Ta 2O 5 thickness in Ta 2O 5/SiO x/Si stacks, the latter showed a lower D it and higher defect density, results attributed to protons and hydroxyl groups, respectively, which stem from water used as an oxidant for the thermal ALD process.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures|
|State||Published - 2006|
ASJC Scopus subject areas
- Condensed Matter Physics
- Electrical and Electronic Engineering