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Description
Reliable non-volatile memories capable of operating under radiation are essential for harsh-environment applications, such as microsatellites in low Earth orbit (LEO). Radiation-tolerant devices can improve mission reliability while reducing system complexity and the need for additional radiation mitigation techniques. Resistive random-access memory (RRAM) is a promising candidate due to its non-volatility, ion-based resistive switching (RS) mechanism, and multi-level storage capability, which significantly enhances memory density. However, its radiation tolerance is still under investigation.
This work studies the total ionizing dose (TID) effects of HfO₂-based one-transistor-one-resistor (1T1R) RRAM arrays fabricated in IHP’s 130 nm BiCMOS technology under X-ray and γ-ray irradiation. Since the access transistor is the most radiation-sensitive element of the memory cell, the array integrates an enclosed layout transistor (ELT) as a radiation-hardened-by-design (RHBD) solution. Memory cells were programmed into four resistance states, i.e., one high resistance state (HRS) and three low resistance states (LRSs), and irradiated up to 1 Mrad(Si). Retention was periodically monitored during irradiation under worst-case conditions, while the electrical characteristics of the stand-alone ELT were also evaluated.
The results indicate a high degree of radiation tolerance under both irradiation sources, with no resistance drift observed during γ-ray exposure. At a higher X-ray dose rate, the stability of the cells was state-dependent. While cells programmed to the LRS showed no resistance drift, approximately 42% of the cells in HRS exhibited resistance variations. The ELT exhibited negligible variations in its electrical characteristics under both irradiation sources. Furthermore, all cells could be reprogrammed and no degradation of the RS parameters was observed after 1 Mrad(Si) exposure.
This work was financially supported by the DFG under Project 551916740.
