Study of thermal properties of tetrakis(dimethylamido)zirconium as a precursor for atomic layer deposition processes

Tetrakis(dimethylamido)zirconium, Zr(NMe₂)₄, TDMAZ, is a sought-after precursor for obtaining ZrO₂ thin films by atomic layer deposition (ALD). Its thermochemical properties are poorly studied, which does not allow for efficient optimization of the layer growth conditions. In this paper, a comprehensive study of the TDMAZ thermal behavior in the condensed and gas phases was conducted. According to tensimetry (a static method with membrane-gauge manometer) results, the gas phase above the liquid compound consists of the dimer molecules Zr₂(NMe₂)₈, while their dissociation presumably to monomers occurs in unsaturated vapor. The temperature dependence of the saturated vapor pressure and the thermodynamic characteristics of the evaporation process in the temperature range of 60–110 °C were determined. According to the mass spectrometric analysis of the gas phase composition, the onset temperature of decomposition of vapor on the heated surface is 240±10 °C, with the maximum degree of thermolysis being achieved at temperatures above 280 °C. Based on the data obtained, temperature limits for vaporization and deposition in ALD processes from TDMAZ were recommended.