Non-volatile memory technologies capable of operating at temperatures exceeding 200°C are critical for applications in harsh environments such as automotive engine control units, aerospace black box recorders, and space-grade computing systems. Conventional flash memory, which relies on charge storage in floating gates, degrades rapidly under thermal stress due to leakage currents, trap-assisted tunneling, and material instability. Emerging solutions, including silicon carbide (SiC)-based resistive random-access memory (RRAM) and ferroelectric memories, offer superior thermal resilience through advanced material engineering and novel switching mechanisms.

Conventional flash memory fails at high temperatures primarily due to three mechanisms. First, increased thermal energy accelerates charge leakage from the floating gate, reducing data retention times. At temperatures above 150°C, the insulating oxide layers that isolate the floating gate experience enhanced electron tunneling, leading to premature charge loss. Second, the dielectric materials used in flash cells, such as silicon dioxide and silicon nitride, undergo structural degradation, including trap generation and interface state formation, which further exacerbates leakage. Third, the metal-oxide-semiconductor (MOS) components suffer from threshold voltage instability due to thermally activated dopant diffusion and gate oxide breakdown. These factors collectively limit flash memory to operating temperatures below 125°C, making it unsuitable for extreme environments.

Silicon carbide-based RRAM presents a promising alternative due to SiC’s wide bandgap (3.2 eV for 4H-SiC), high thermal conductivity (4.9 W/cm·K), and chemical inertness. RRAM operates by forming and rupturing conductive filaments in an insulating matrix, a mechanism less sensitive to thermal fluctuations than charge storage. SiC’s high breakdown field (3 MV/cm) ensures stable resistive switching even at elevated temperatures. Studies have demonstrated that SiC RRAM devices maintain stable resistance states with minimal drift at 300°C, with endurance exceeding 10^5 cycles. The key to this performance lies in the selection of electrode materials and switching layers. For example, tungsten (W) and platinum (Pt) electrodes paired with SiC or hafnium oxide (HfO₂) switching layers exhibit reduced ion migration and filament instability under thermal stress.

Ferroelectric memories, particularly those utilizing hafnium zirconium oxide (HZO), offer another high-temperature solution. Unlike traditional ferroelectric materials like lead zirconate titanate (PZT), which suffer from fatigue and imprint at high temperatures, HZO-based ferroelectric field-effect transistors (FeFETs) exhibit robust polarization retention. The orthorhombic phase of HZO, stabilized through careful doping and annealing, maintains its ferroelectric properties up to 400°C. FeFETs store data via polarization switching in the gate dielectric, eliminating charge leakage concerns. Recent experiments show that HZO FeFETs retain over 80% of their initial polarization after 10^4 cycles at 250°C, making them suitable for long-term data storage in harsh conditions.

In engine control units (ECUs), high-temperature non-volatile memory ensures reliable operation near combustion chambers, where ambient temperatures can exceed 200°C. Conventional electronics require bulky cooling systems, increasing weight and complexity. SiC RRAM and FeFETs enable compact, energy-efficient ECUs with direct integration into hot zones, improving response times and reducing system failures. Black box recorders in aerospace applications demand memory that survives not only high temperatures but also mechanical shock and radiation. The inherent radiation hardness of SiC, combined with the thermal stability of RRAM, meets these stringent requirements. Space-grade computing systems benefit from these technologies by eliminating the need for thermal shielding, reducing payload mass, and enhancing mission longevity.

Material innovations continue to push the boundaries of high-temperature memory. For RRAM, research focuses on optimizing filament composition and interface engineering to suppress thermal diffusion. Doping switching layers with aluminum or nitrogen enhances thermal stability by increasing the activation energy for ion migration. In ferroelectric memories, scaling HZO thickness while maintaining crystallinity improves switching uniformity and reduces operating voltages. Emerging concepts like interfacial phase-change memory (iPCM) and oxide-based conductive bridge RAM (CBRAM) also show potential for extreme-temperature operation, though further development is needed to match the maturity of SiC RRAM and HZO FeFETs.

The transition from lab-scale demonstrations to industrial adoption requires addressing manufacturing challenges. SiC RRAM necessitates precise control over stoichiometry and defect density during deposition, while HZO FeFETs demand atomic-level uniformity in thin-film growth. Advances in atomic layer deposition (ALD) and molecular beam epitaxy (MBE) are critical for achieving the required material quality. Standardization of reliability metrics, such as data retention at 300°C and cycling endurance under thermal shock, will accelerate commercialization.

Non-volatile memory technologies capable of withstanding extreme temperatures are enabling a new generation of electronics for demanding environments. By overcoming the limitations of conventional flash through material innovation and novel switching mechanisms, SiC RRAM and ferroelectric memories are paving the way for reliable high-temperature operation in automotive, aerospace, and space applications. Continued research into material stability and device architecture will further enhance performance, ensuring these technologies meet the growing demands of industrial and mission-critical systems.