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- Title
Comparative study of pulsed laser deposited HfO<sub>2</sub> and Hf-aluminate films for high-kgate dielectric applications.
- Authors
Zhu, J.; Liu, Z.G.
- Abstract
The thermal stability and the electrical properties of HfO2 and Hf-aluminate films prepared by the pulsed laser deposition technique have been investigated by X-ray diffraction, differential thermal analysis, capacitance-voltage correlation, leakage-current measurements and high-resolution transmission electron microscopy observation, respectively. A crystallization transformation from HfO2 amorphous phase to polycrystalline monoclinic structure occurs at about 500 °C. In contrast, the amorphous structure of Hf-aluminate films remains stable at higher temperatures up to 900 °C. Rapid thermal annealing at 1000 °C for 3 min leads to a phase separation in Hf-aluminate films. Tetragonal HfO2(111) is predominant, and Al2O3 separates from Hf-aluminate and is still in the amorphous state. The dielectric constant of amorphous HfO2 and Hf-aluminate films was determined to be about 26 and 16.6, respectively, by measuring a Pt/dielectric film/Pt capacitor structure. A very small equivalent oxide thickness (EOT) value of 0.74 nm for a 3-nm physical thickness Hf-aluminate film on a n-Si substrate with a leakage current of 0.17 A/cm2 at 1-V gate voltage was obtained. The interface at Hf-aluminate/Si is atomically sharp, while a thick interface layer exists between the HfO2 film and the Si substrate, which makes it difficult to obtain an EOT of less than 1 nm.
- Subjects
THIN films; DIELECTRICS; PULSED laser deposition; X-ray diffraction; THERMAL analysis
- Publication
Applied Physics A: Materials Science & Processing, 2005, Vol 80, Issue 8, p1769
- ISSN
0947-8396
- Publication type
Article
- DOI
10.1007/s00339-003-2479-8