Capacitors based on hafnium zirconium oxide atomic layer deposition with CMOS applications

In the last 5 years, has been a surge of technological interest in ferroelectric hafnium zirconium oxides (HZO) thin films as ferroelectric materials for emerging memories. Ferroelectricity in fluorite type of ferroelectric oxides has been explained by appearance of polar orthorhombic Pca21 phase in HZO or HfO2 polymorphic oxides. Thickness downscaling, grain size, or doping, with transitional metals, are known to favour stabilization of desired orthorhombic phase. However, the ferroelectric properties under applied electrical field (such as remanent polarization, coercive field and especially endurance) are strongly dependent on the adjacent layers present in the final device stacks (metals, semiconductor, and dielectric oxides) and the thermal treatment process conditions. High endurance and wake-up free ferroelectric stacks with sustained remanent polarization can be achieved by careful tuning of dopant content, layers thickness and the choice of the metal electrodes and interfacial layers. To achieve this target, we need to carefully tune the characteristics of the films through understanding the first stages of the film growth by atomic layer deposition, paying particular attention to the interfacial regions between the ferroelectric oxide and metal electrodes. The surface, bulk, and interfacial properties of the films will be studied using the existing physical and chemical analyses tool available at imec and finally correlate their characteristics with their electrical properties (such as remanent polarization, coercive field, endurance, and capacitance).