Atomic layer deposition of Er2O3 thin films from Er tris-guanidinate and water: process optimization, film analysis and electrical properties

For the first time, the combination of the homoleptic erbium tris-guanidinate metalorganic complex ([Er(NMe2-Guan)(3)]) simply with water yielded high quality Er2O3 thin films on Si(100) substrates employing the atomic layer deposition (ALD) process. The process optimization to grow good quality Er2O3 layers was performed by varying the Er precursor pulse time, water pulse time and purge time. The high reactivity of the Er compound towards water and good thermal stability in the temperature range of 150-275 degrees C (ALD window) resulted in homogeneous, stoichiometric Er2O3 layers with high growth rates (1.1 angstrom per cycle) and the as-deposited films crystallized in the cubic phase. The saturation behavior at different temperatures in the ALD window and the linear dependence of film thickness as a function of precursor pulse time confirmed the true ALD process. The potential of Er2O3 thin films as gate dielectrics was verified by performing capacitance-voltage (C-V) and current-voltage (I-V) measurements. Dielectric constants estimated from the accumulation capacitance were found to be in the range of 10-13 for layers of different thicknesses (15-30 nm).