Calcium fluoride (CaF₂) is a wide-bandgap dielectric material with broad optical applications due to its wide range of transparency. Defects in its crystal structure can affect these properties, making it important to understand the formation and behavior of such defects. This study investigates electron trapping in the silicon dioxide (SiO₂) layer during electron beam deposition of 50-277 nm thick CaF₂ thin films on Si/SiO₂ substrates. The Si/SiO2 substrates consisted of a thermally grown amorphous 1 µm thick SiO2 layer on a Si wafer. The photoelectron emission (PE) technique was used to study charge transfer and trapping in SiO₂. The PE current was excited by UV photons with an energy range of 4-6 eV. The results demonstrated that the deposition of CaF₂ films filled electron traps in the SiO₂ layer by the mechanism explained in [1], leading to the appearance of distinct maxima in the PE spectra. These maxima persisted for several days in 125 nm or thinner films but relaxed within several hours in 277 nm films when exposed to air. This difference is attributed to different concentrations of ionized F centers at the SiO₂-CaF₂ interface. These results were explained by a proposed scheme suggesting that the high irradiation dose during the fabrication of the 277 nm thick film led to the formation of a region with an increased concentration of ionized F centers at the SiO2-CaF2 interface. When the films were exposed to air, additional defects known as (O2--VA) centers were formed. The intensity of the PE spectrum then underwent a relatively rapid relaxation due to electron transfer from SiO2 traps to (O2--VA) centers. In films with a thickness of 125 nm or less, the relaxation is much slower due to the low concentration of ionized F centers. In addition, the study confirmed the possibility of a 260 nm electron escape depth for CaF2 material.