Abstract: Conventional chalcogenide materials are hard to remain ferroelectricity when miniatured and poorly compatible with CMOS, hafnium zirconium oxide （HZO） ferroelectric devices compensate the intrinsic defects of conventional chalcogenide with their ability to be miniaturized to within 10 nm with good ferroelectric capacity and still have good compatibility with CMOS. That is why HZO materials have attracted much attention from academia and industry, this material is a promising alternative to dynamic random memories for non-volatile ferroelectric memories （FERAM） and ferroelectric transistor-based integrated circuits. Based on the most widely used TiN/HZO/TiN stack, the in-situ ALD technique with high-end application prospects was used to grow TiN electrodes, and the growth rate of the electrode layers and their nanometer-scale film thickness were well controlled. The diffusion of elements at the stack interface was investigated, and the phenomenon of external diffusion of interfacial elements was found by time-of-flight secondary ion mass spectrometry. The mechanism of the external diffusion behaviour was investigated by angle-resolved X-ray photoelectron spectroscopy, and a possible theoretical explanation was proposed, i.e., the external diffusion of interfacial elements due to the surfactant effect triggered by the redox reaction between TiN and HZO. This work shed light to the application of HZO-based FERAM.