Nuclear Research Institute Develops 'Radiation-Hardened' Technology for Aerospace Nano Semiconductors

A semiconductor radiation-hardening technology against protons, which account for more than 80% of space radiation, has been developed domestically.

Space contains a large amount of various radiations, and radiation accounts for more than 30% of the causes of failures in products using semiconductors. This is why radiation-hardening technology that can withstand radiation is considered important in the development process of next-generation aerospace semiconductors.

(From left) Dr. Lee Yongsoo of the Korea Atomic Energy Research Institute (first author), Dr. Kang Changgu (corresponding author), and Professor Lee Byunghoon of Pohang University of Science and Technology (corresponding author). Provided by Korea Atomic Energy Research Institute

The Advanced Radiation Research Institute of the Korea Atomic Energy Research Institute (KAERI) announced on the 6th that Dr. Chang-Koo Kang's team from the Radiation Convergence Research Division and Professor Byung-Hoon Lee's team from Pohang University of Science and Technology (POSTECH) jointly developed a radiation-hardening technology that significantly suppresses nano-semiconductor errors.

The radiation-hardening technology developed by the joint research team physically separates the semiconductor surface from the external environment by stacking a passivation layer that blocks water and oxygen in the atmosphere, thereby suppressing nano-semiconductor errors caused by protons.

Using the atomic layer deposition method, which creates a gaseous state of material and chemically deposits a thin layer on the surface, a 10 nm thick aluminum oxide (Al2O3) passivation layer is stacked on the surface of zinc oxide (ZnO)-based nano-semiconductors.

The joint research team irradiated protons using a proton accelerator on both semiconductors with and without the passivation layer and compared and analyzed changes in electrical characteristics. As a result, they confirmed that the passivation layer very effectively suppresses changes in the electrical characteristics of semiconductors caused by proton irradiation.

Schematic diagram of radiation shielding technology for aerospace nano semiconductors. Provided by Korea Atomic Energy Research Institute

The health of a semiconductor is judged by changes in the ‘threshold voltage,’ which is the minimum voltage for current to flow, the ‘hysteresis index,’ which indicates changes in semiconductor output under the same conditions, the semiconductor’s ‘stress index,’ and the ‘noise value,’ which is an unwanted signal during semiconductor operation.

In the comparative analysis, semiconductors protected by the passivation layer showed a 60% reduction in threshold voltage change, and a 90% reduction in changes in hysteresis index and stress index after proton irradiation compared to unprotected semiconductors. Notably, the noise value was confirmed to remain unchanged even after proton irradiation.

This establishes a technological foundation capable of effectively protecting semiconductors from protons, which constitute the majority of space radiation. The joint research team expects that the developed technology will be utilized as a core technology for implementing radiation-hardening systems in next-generation aerospace nano-semiconductors.

The joint research team plans to advance the radiation impact evaluation analysis system to elucidate the detailed mechanisms of semiconductor radiation-hardening technology and continue research on radiation-hardened semiconductors at various circuit levels.

This research was conducted with the support of the Basic Research Project in Science and Engineering Fields by the Ministry of Science and ICT. The research results were published in the January issue of the international journal Nano Convergence.

Jung Byung-Yeop, director of the Advanced Radiation Research Institute at KAERI, said, “The technology developed by the joint research team is significant in that it is a case where a passivation layer was stacked on next-generation nano-semiconductors using atomic layer deposition and the actual radiation-hardening effect was verified.”