The central objective of this dissertation is to investigate thermal resilience of FeRAM for advanced 3D memory-on-logic architecture. In such architectures, the stacked configuration results in elevated operating temperatures, making thermal management a significant challenge. To address this challenge, this work systematically explores the interplay among oxygen-reservoir interfacial layers, ALD deposition techniques, and electrode materials in ferroelectric capacitors, and investigates how these factors govern defect chemistry, phase stability, and microstructural evolution in fluorite ferroelectrics. Because the microstructure of fluorite ferroelectrics plays a critical role in determining device performance and reliability, detailed studies of domain wall structures, their characteristics, and grain size statistics have been conducted. By combining materials engineering, process optimization, and microstructural analysis, this dissertation explores strategies to realize thermally robust ferroelectric capacitors with improved endurance and stable polarization behavior. These insights provide practical design guidelines for ferroelectric devices intended for reliable operation across a wide temperature range.