In this study, we investigate the reaction mechanisms of precursor adsorption during the atomic layer deposition (ALD) using density functional theory (DFT) calculations and ideal-gas methods; herein, we considered adsorption of tris(dimethylamino)silane (TDMAS) on a hydroxylated SiO₂ surface to be the example for our investigation. When the reaction free energy is calculated, the DFT results obtained at 0 K suggest that the dissociation of a hydrogen atom from TDMAS is favorable upon TDMAS adsorption, which is inconsistent with the experimental results where one dimethylamino group is released. The experimental results can be accurately predicted when enthalpy and entropy changes are considered at elevated temperatures, thereby indicating the significance of finite-temperature effects in free-energy changes for solid-gas reactions. We analyze the changes in enthalpy and entropy and find that dimethylamine is a more favorable gaseous product than H₂ owing to its larger translational and rotational entropy.

在这项研究中，我们使用密度泛函理论 (DFT) 计算和理想气体方法研究了原子层沉积 (ALD) 过程中前体吸附的反应机制；在此，我们考虑了三（二甲氨基）硅烷（TDMAS）在羟基化 SiO ₂上的吸附表面作为我们调查的例子。当计算反应自由能时，在 0 K 下获得的 DFT 结果表明，TDMAS 吸附时氢原子从 TDMAS 上解离是有利的，这与释放一个二甲氨基的实验结果不一致。当考虑高温下的焓变和熵变时，可以准确预测实验结果，从而表明有限温度效应对固气反应自由能变化的重要性。我们分析了焓和熵的变化，发现二甲胺是比 H ₂更有利的气态产物，因为它具有更大的平移和旋转熵。