Rad (radiation) Hard Devices used in Space, Military Applications, Nuclear Power in-situ Instrumentation Savanna Krassau 4/21/2017 Abstract: Environments with large amounts of radiation create design challenges for integrated circuits. A single charged particle can knock loose thousands of electrons, resulting in noise, signal spikes, inaccurate data and worse: total system failure.

Introduction to Rad Hard Devices The Need for Rad Hard Devices Types of Radiation Types of Radiation Damage Rad Hard Solutions Physical Rad-Hardening Techniques Logical Rad-Hardening Techniques

Dead Robots Fukushima

Outer Space

Types of Radiation Cosmic Rays: protons, alpha particles, heavy ions with x-ray and gamma-ray radiation Solar Particle Events: from the sun, protons and heavy ions with x-ray radiation Nuclear Reactors: produce gamma and neutron radiation

Types of Radiation Damage Semiconductors are susceptible to radiation Perspective: Human workers have a 2-5 rads/year limit. Most commercial electronics can survive ration levels in silicon of at least 500-1000 rads Single Event Effects Caused by one single energetic particle Total Ionizing Dose Effects A measure of how much radiation has accumulated over the lifetime of the device

Single Event Effects in Detail Single Event Upsets Errors caused by ionizing the medium they pass through leaving electron-hole pairs Single Event Latchup More and more current is dragged into the substrate which can cause the entire circuit to breakdown Single Event Burnout A heavy ion passed through a transistor and deposited enough charge to turn the transistor on

Total Ionizing Dose Effects in Detail Cumulative Damage Measured by Industry Causes slow gradual degradation of device’s performance However, a total dose of 5000 rads to delivered to a Si based device seconds to minutes will cause long term damage Energy is absorbed in SiO2 liberates charge carries which diffuse or drift to other locations where they are trapped

Physical Rad-Hardening Techniques Insulating Substrates Radiation-tolerant SRAM Wide band-gap Substrate Shielding the Package against Radioactivity Shielding the chips by using Depleted Boron

Logical Rad-Hardening Techniques Error Correcting Memory Uses parity bit and a scrubber circuit continuously sweeps the RAM Redundant Elements Duplication of critical components, or three component voting system Watchdog Timers Hard reset if watchdog is allowed to timeout

Conclusion Electronics for Space, the Military, and Nuclear Power Applications have to meet requirements which are very different from those or ordinary consumer products because they need to withstand higher levels of radiation

References http://www-physics.lbl.gov/~spieler/radiation_effects/rad_tutor.pdf http://www.datarespons.com/electronics-in-space/ http://spectrum.ieee.org/tech-talk/semiconductors/design/radiationhardening-101 http://www.huffingtonpost.com/entry/fukushima-anniversary-robots_us_56e62cdae4b065e2e3d65712 https://www.nasa.gov/feature/goddard/real-martians-how-to-protect-astronauts-from-space-radiation-on-mars http://news.stanford.edu/2017/03/28/new-nano-devices-withstand-extreme-environments-of-space/

Five Take Away Points There is a need for Rad Hard devices because of extreme environments with high levels of radiation Types of radiation: cosmic, solar, and nuclear Single Event Effects are caused by a single energized particle Total Ionizing Dose is cumulative radiation There are techniques both physical and logical to make devices radiation resistant