The Evaluation of Interface Quality in HfO₂ Films Probed by Time-Dependent Second-Harmonic Generation

Time-dependent second-harmonic generation (TD-SHG) is an emerging sensitive and fast method to qualitatively evaluate the interface quality of the oxide/Si heterostructures, which is closely related to the interfacial electric field. Here, the TD-SHG is used to explore the interface quality of atomic layer deposited HfO₂ films on Si substrates. The critical SHG parameters, such as the initial SHG signal and characteristic time constant, are compared with the fixed charge density ((Formula presented.)) and the interface state density ((Formula presented.)) extracted from the conventional electrical characterization method. It reveals that the initial SHG signal linearly decreases with the increase in (Formula presented.), while (Formula presented.) is linearly correlated to the characteristic time constant. It verifies that the TD-SHG is a sensitive and fast method, as well as simple and noncontact, for evaluating the interface quality of oxide/Si heterostructures, which may facilitate the in-line semiconductor test.