The impact of process technology (the fabrication process used to manufacture integrated circuits) on MCU radiation tolerance is a critical consideration for space missions, aerospace applications, and other scenarios where exposure to ionizing radiation is a concern. Let%27s explore this topic in detail:

1. Radiation Effects on MCUs:
- MCUs, like all semiconductor devices, are susceptible to radiation-induced effects when exposed to high-energy particles (such as cosmic rays, solar particles, or terrestrial radiation).
- Ionizing radiation can cause various issues, including:
- Single Event Effects (SEEs):
- Single Event Upsets (SEUs): Bit flips due to charge deposition in sensitive regions (e.g., memory cells, flip-flops).
- Single Event Latchup (SEL): Parasitic thyristor-like behavior triggered by heavy-ion strikes.
- Single Event Transients (SETs): Temporary voltage spikes caused by charge collection.
- Total Ionizing Dose (TID) Effects:
- Gradual accumulation of radiation damage over time.
- Threshold voltage shifts, leakage current increase, and performance degradation.
- Displacement Damage Effects:
- Atomic displacement due to neutron interactions.
- Can lead to long-term degradation of device properties.
- Dose Rate Effects:
- Radiation dose rate affects the severity of damage.
- High dose rates can cause prompt effects (e.g., SEE), while low dose rates lead to gradual degradation.

2. Process Technology Impact:
- The choice of process technology significantly influences MCU radiation tolerance:
- Feature Size (Node):
- Smaller feature sizes (e.g., 28nm, 14nm, 7nm) increase sensitivity to radiation.
- Reduced feature sizes lead to thinner gate oxides, smaller transistors, and higher charge collection probabilities.
- However, advanced nodes also offer better performance and power efficiency.
- Technology Node Innovations:
- FinFETs (used in modern processes) exhibit improved radiation hardness compared to planar transistors.
- SOI (Silicon-on-Insulator) technology reduces charge collection.
- Triple Well Structures enhance radiation tolerance.
- Process Variability:
- Smaller nodes are more sensitive to process variations.
- Variability affects device parameters (threshold voltage, oxide thickness) and can impact radiation response.
- Metal Layers and Interconnects:
- Metal layers contribute to the overall radiation hardness.
- Advanced processes use more metal layers, which can mitigate radiation effects.
- Gate Oxide Thickness:
- Thinner gate oxides increase sensitivity to radiation.
- Designers must strike a balance between oxide thickness and performance.
- Doping Profiles:
- Well-controlled doping profiles affect radiation response.
- Properly designed wells and isolation structures enhance radiation tolerance.

3. Mitigation Techniques:
- Error Correction Codes (ECC):
- ECC schemes detect and correct memory errors caused by radiation.
- Used in flash memory, RAM, and other storage elements.
- Redundancy Techniques:
- Redundant elements (e.g., redundant rows/columns in memory arrays) allow recovery from radiation-induced faults.
- Shielding and Packaging:
- Shielding materials (e.g., metal cans) protect sensitive components.
- Hermetic packaging reduces moisture and contamination.
- Radiation-Hardened Libraries:
- Specialized libraries with radiation-hardened cells.
- Used in critical parts of the design.

4. Conclusion:
- Process technology impacts MCU radiation tolerance.
- Designers must balance performance, power, and radiation hardness.
- Rigorous testing and simulation are essential to validate radiation performance.

In summary, process technology choices significantly affect MCU radiation tolerance. Advanced nodes offer better performance but require careful design to mitigate radiation effects¹²³.


(1) 2019 NEPP ETW: Radiation Effects on ARM Devices. https://nepp.nasa.gov/workshops/etw2019/talks/0619WED/0830 - Guertin - ARMETW_2019_V6_pres.pdf.
(2) Evaluation of Ionizing Radiation Effects on Device Modules ... - Springer. https://link.springer.com/article/10.1007/s10836-020-05890-5.
(3) STM32H753 vs STM32H23 radiation tolerance - STMicroelectronics Community. https://community.st.com/t5/stm32-mcus-products/stm32h753-vs-stm32h23-radiation-tolerance/td-p/595991.
(4) Radiation Effects on Digital Devices | SpringerLink. https://link.springer.com/chapter/10.1007/978-3-031-15717-2_3.

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