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摘要
Tetrakis-diethylamino hafnium (TDEAH), tris-diethyl amino aluminum (TDEAA), and ozone were used for the atomic layer deposition (ALD) of HfO2, Al2O3, and HfAlOx films. The ALD rates were measured to be 1.1 angstrom/cycle for HfO2 and 1.3 angstrom/cycle for Al2O3. The ALD temperature windows were found to be between 200 and 325 degrees C for TDEAA, and between 200 and 275 degrees C for TDEAH. The overlap of these ALD windows between 200 and 275 degrees C is critical for ALD of the composite film, HfAlOx. In addition to the overlapping ALD temperature windows, the two metal precursors have similar thermal characteristics, as shown by TGA and differential scanning calorimetry. As-deposited films and films postannealed at 600 and 800 degrees C films were analyzed using Fourier transformed infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy, and x-ray diffraction (XRD) techniques. FTIR spectra revealed interfacial oxide growth during deposition of both HfO2 and Al2O3 whose thickness increased with annealing temperature. The FTIR data also indicated hydroxyl and nitrate groups in the films; these species were removed after annealing in Ar at a temperature of >= 600 degrees C. Both FTIR and XRD results indicated the crystallization of pure HfO2 after annealing at temperatures as low as 600 degrees C. On the other hand, pure Al2O3 remained amorphous after annealing at temperatures up to 800 degrees C. XRD data of the composite HfAlOx film show that films deposited by alternating five cycles of HfO2 and one cycle of Al2O3 remained amorphous after annealing at 600 degrees C. Rutherford backscattering analysis of HfAlOx deposited with a varied number of alternating HfO2 and Al2O3 cycles demonstrated a strong correlation between the cyclic dosage of TDEAA and TDEAH and the film composition.
- 出版日期2007-12
