Dynamics of Interactions Between HF and Hafnium Oxide During Surface Preparation of High-K Dielectrics

The interactions of HF with hafnium oxide are important aspects of the post-etch cleaning of high-k dielectrics. The dynamics of these interactions during typical wafer rinsing are studied using a quartz crystal microbalance (QCM) equipped with a flow-through cell. A process model is developed showing that the overall rinse process consists of three simultaneous steps: adsorption, desorption, and etching involving fluoride species. The model is validated using the experimental data obtained in QCM. The key parameters of these process steps, namely, adsorption, desorption, and etch rate coefficients are determined using the combined experimental measurement and process modeling.