The local cathodoluminescence is used to study the point defects and their depth distribution in silicon oxide and silicon. The defects formed by two-coordinate silicon (Si=Si), oxygen vacancies (Si-Si, Si-Si-Si), non-bridgen oxygen (-O.), amorphous silicon and silicon nanoclusters have characteristic emission bands. High sensibility of cathodoluminescence method permits to study natural silicon oxide film, thin silicon oxide and silicon layers near the interface. In this paper an influence of the silicon type on the properties of SiO2/Si interface is discussed. It is shown that the quality of SiO2/Si interface depends not only on the technology process but on the silicon type and activator concentration. A high boron content in silicon leads to an increase of point defects concentration in silicon oxide and sometimes to an appearance of Si nanoclusters near the interface in the layer with 10-20 nm thickness. The concentration of intrinsic defects near the silicon oxide – n-silicon interface depends also on phosphorous concentration. But in this case low concentration of activator leads to a presence of high content of intrinsic defects in the first monolayers of silicon oxide and to a dramatical decrease of a content of these defects in films with thickness of more that 10 nm. On the contrary, the high concentration of activators leads to low content of intrinsic defects near the interface and a rise of its content in the film with thickness more that 10 nm.