Thermal Atomic Layer Deposition of TiNx Using TiCl4 and N2H4

Atomic layer deposition (ALD) of titanium nitride (TiN) is carried out by the alternate surface reactions of titanium tetrachloride (TiCl4) and hydrazine (N2H4) at temperatures ranging from 150 to 350°C. The film deposition process is monitored in situ by quartz piezoelectric microweighing (QPM) and Fourier transform infrared spectroscopy (FTIRS). The QPM data detects the self-limiting character of the surface reactions between TiCl4 and N2H4, as well as the linearity of the film growth with the number of cycles at 200 and 225°C. The growth constant of the TiNx film is found to be 0.36 A/cycle at the optimum growth temperature of 275°C. The roughness and density of the 116.3-A-thick film deposited at this temperature are determined to be 7.2 A and 87.5% (of the TiN volume’s density), respectively. The X-ray photoelectron spectroscopy (XPS) analysis of these films shows the content of chlorine impurities to be below the instrument’s sensitivity limit (<0.2 аt %) and the oxygen content to be near 14 at %. The X-ray diffraction measurements indicate the cubic polycrystalline structure of these films. The FTIRS method is used for surface deposition chemistry at 200 and 275°C. The possibility of depositing titanium-aluminum nitride (TiAlxNy) films by ALD with trimethylaluminum (TMA) as a precursor is also shown. Films deposited at 275°С are found to contain oxygen and chlorine impurities near 3 and 4 at %, respectively.