Thin Ga2O3 insertion layer for phase structure and electrical property evolutions in ferroelectric Hf0.5Zr0.5O2 capacitors

Abstract

In this study, gallium oxide (Ga2O3) insertion layers (ILs) of varying thicknesses were embedded within Hf0.5Zr0.5O2 (HZO) films using atomic layer deposition (ALD). Devices with Ga2O3 ILs grown for fewer than 4 ALD Ga2O3 cycles exhibit a reduction in both remnant polarization (Pr) and coercive field (Ec). Notably, the device incorporating a IL with 2 ALD Ga2O3 cycles demonstrates strong performance, achieving a 2Pr of 47.0 μC/cm2 and an Ec of 0.92 MV/cm. In contrast, for devices with ILs exceeding 8 ALD Ga2O3 cycles, the 2Pr value remains near 18 μC/cm2, while Ec increases significantly. These divergent behaviors can be attributed to the different diffusion states of the insertion IL. For a low number of ALD Ga2O3 cycles, it is the diffusion of Ga3+ ions into the HZO region adjacent to the IL that results in a reduced Ec. Conversely, with higher ALD Ga2O3 cycles, the IL forms a continuous layer that physically divides the 10 nm HZO film into two sections, which leads to a further decrease in Pr and an increase in Ec. Furthermore, the progressive disruption of vertical grain boundaries by the growing insertion layer (IL) leads to a continuous decrease in leakage current. This work demonstrates the effective modulation of HZO devices via a Ga2O3 insertion layer, offering a methodology and data reference for enhancing device reliability.