The interface trap level density, D-it, is one of the most important parameters of the SiO2-Si layer structure. C-V methods are suitable for measuring D-it. However, the importance of non-destructive, touch-free methods has recently been increasing. Contactless methods use capacitive coupling. Vibration (vibrating capacitor), temperature difference and light are used for surface excitation; interface trap level density can be determined from the change in the value of oxide surface potential (work function). The present article discusses a new method for determining SiO2-Si interface trap level density, D-it, by the vibrating capacitor method, focussing on theory, application and evaluation of the results. Measured potential maps are presented, and the results are converted into D-it distributions as examples for the application of this method.