Effect of film composition and structure on the crystallization point of atomic layer deposited HfAlOx using metal (diethylamino) precursors and ozone

Atomic layer deposition (ALD) of HfAlOx on Si(1 0 0) was carried out using tetrakis-diethylamino hafnium (TDEAH) and tris-diethylamino aluminum (TDEAA) as metal precursors and ozone as oxidizer. ALD temperature windows of TDEAA and TDEAH overlapped between 200 and 275 °C, which is critical for ALD of composite HfAlOx films. Rutherford backscattering analysis of HfAlOx shows a strong correlation between the number of ALD cycles of alumina and hafnia being alternated and the film composition. Grazing incidence X-ray diffraction analyses of thermally annealed films indicate that a higher Al concentration increases the crystallization temperature and degree of crystallization. In addition to composition, crystallization of HfAlOx film also depends on the film structure defined by the deposition cycle sequence. For example, films deposited by alternating TDEAH/O3 and TDEAA/O3 cycles in a 2:1 ratio were found to have a lower degree of crystallization than films deposited by alternating in a 4:2 ALD cycle ratio, even though the ratios of Hf and Al are the same.