Over the last 50 years, the effects of cumulative radiation damage in microelectronics, and now nanoelectronics, have continually presented a design and assurance challenge to space flight missions. Feature sizes, that is, the size of the unit structure in microelectronics, has continually decreased, which has presented an added complexity to testing and assuring microelectronic devices. This paper outlines the paradigm shifts of total ionizing dose (TID) and displacement damage (DD) effects as device sizes have reduced and highlights some of the strategies developed to insert apply microelectronics into space. The current trends of the technology are analyzed in context of future JPL and NASA missions.

This chapter reviews the effects of space radiation on microelectronic devices, and shows how device scaling has affected their vulnerability to radiation. The most dramatic impact has been on single-particle effects, particularly those caused by galactic cosmic rays. New effects can occur at the microscopic level, including permanent damage from the interaction of a single energetic particle when it strikes the gate of a metal oxide semiconductor (MOS) transistor. Scaling also impacts device complexity, not only because advanced circuits use such large number of transistors but also because of the complex processing steps needed to design individual transistors that can function with such small feature sizes and meet the requirements necessary for competitive performance. Many of the practical problems that need to be addressed in space are related to the complex design methods used to fabricate scaled devices.

As part of an on-going “data mining” effort, the response to single event upsets (SEU) of the Clementine 2.1 Gb Solid State Data Recorder (SSDR) was compared to that of the two Cassini 2.5 gigabit (2.1 Gb usable for data) Solid State Recorders (SSRs) to see what lessons could be learned. Both systems were evaluated for their sensitivities to SEUs before flight. Estimates of the in-situ environments for the two missions allow evaluation of the ability of SEU models and ground tests to predict flight performance using actual data. The DRAMS that make up the solid state recorders, despite having different manufacturers, appear to have similar SEU cross-sections. This similarity has permitted a comparison of the effects of the ambient environments on the systems for two very different missions (lunar versus Saturn). Initial results from previous studies had revealed a nearly constant background upset rate for both systems of ~71 bit flips/day for the SSDR and ~280 for the SSRs due to the Galactic Cosmic Ray background. While there was no obvious correlation with a solar proton event recorded by Clementine on 20-21 February 1994 nor with trapped protons during its brief passage through the Earth’s radiation belts, the Cassini SSRs showed pronounced responses to both solar proton event and Saturn trapped radiation environments. This difference is explained here by applying the proton cross-sections measured for Cassini to the Clementine observations—the new results show that the protoninduced upset rates would have been too low to be observed by Clementine. This study completes the original Clementine SSDR analyses and, in the process, demonstrates agreement between the Cassini SSR upsets and the JPL SATRAD proton radiation model. Finally, the lunar orbit variations in the SSDR upset rates observed by Clementine are reevaluated using a new methodology—the pronounced lunar orbit altitude dependence is shown to fit the expected variation in GCR fluxes due to lunar shielding.

A new methodology for using scanning picosecond laser microscopy to simulate cosmic ray induced radiation effects as a function of temperature is described in detail. The built system is centered on diffraction-limited focusing of the output from a broadband (690-960 nm) ultrafast Ti:sapphire Tsunami laser pumped by a 532 nm Millennia laser. An acousto-optic modulator is used to provide pulse picking down to event rates necessary for the technologies and effects under study. The temperature dependence of the charge generation process for ions and photons is briefly reviewed and the need for wavelength tunability is discussed. An appropriate wavelength selection is critical for proper emulation of ion events over a wide temperature range. The system developed is detailed and illustrated by way of example on a deep-submicron complementary metal-oxide semiconductor test structure.

Radiation damage is investigated in optocouplers with power MOSFET output stages. They differ from conventional optocouplers, incorporating an intermediate photovoltaic chip to allow the MOSFET gate voltage to be controlled by the light-emitting diode. These optocouplers are sensitive to ionization as well as displacement damage, and can fail catastrophically from degradation in either the power MOSFET or the LED. Radiation testing must take both mechanisms into account.

dose irradiations for the AD8233 LM1 36-2.53 (ELDRS) High Dose Level (HDL), Low Dose Level (LDL), Total LTc1417, MC35072, DG304A, and the AD590 were Ionizing Dose (TID) performed at the high and low dose rate (HDR and LDR) Co- I. INTRODUCTION HIS paper reports recent Total Ionizing Dose (TID) test T results obtained at the Jet Propulsion Laboratory (JPL). The results discussed in this paper refer to testing performed during the past year. These microelectronic devices were candidates for applications in space missions. Two of these part types are built on bulk CMOS processes. The other parts are fabricated on conventional linear bipolar processes which make them susceptible to enhanced low dose rate sensitivity (ELDRS) (1)-(3). In addition, unbiased bipolar devices are often more sensitive to radiation damage at low dose rates than biased devices (4). The objective in most cases is to determine whether the biased or unbiased condition represents the worst- case condition during irradiation and to determine if these devices are susceptible to ELDRS. The results described below characterize these devices for use in a wide range of dose environments of space.

Abstract

GaAs micro-electromechanical RF relays fabricated by surface micromachining techniques were characterized for their response to total ionizing dose. Microrelays with two different geometries were studied. For one geometry, changes in switch actuation voltage at moderate dose levels were observed. For an alternative geometry, no change in actuation voltage was observed. A mechanism for dielectric charge trapping and its effect on the electrostatic force is proposed.

This paper documents radiation effects observed in selected spacecraft at the system and subsystem levels, and where possible, relates them to predicted radiation effects in parts. Comparisons are also made as functions of design paradigm, assurance philosophy, and the vintage and complexity of the parts and the system.

Total dose tests of six different low dropout voltage regulators show sensitivity to both dose rate and bias during exposure. All devices tested exhibited Enhanced Low Dose Rate Sensitivity (ELDRS) and performed worse for the unbiased irradiation condition. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact on hardness assurance methodology is discussed.

Spacecraft performance requirements drive the utilization of commercial-off-the-shelf (COTS) components and emerging technologies in systems. The response of these technologies to radiation is often complex. This engenders a set of emerging radiation hardness assurance (RHA) issues which include displacement damage in optocouplers, high-precision and hybrid devices, enhanced low dose rate (ELDR) and proton damage enhancement (PDE) in linear circuits, linear transients, and catastrophic single event effects (SEEs) phenomena. NASA has developed an approach to designing reliable space systems which address these emerging RHA issues. This programmatic methodology includes hazard definition, hazard evaluation, requirements definition, evaluation of device usage, and application of radiation engineering techniques with the active involvement of designers. Risk assessment is an integral constituent in the approach as is an established program to assess future technology needs for programs.

The effects of irradiation at very low dose rates are discussed for hardened CMOS devices from two different manufacturers. For some devices, rate effects were important even at dose rates of 0.04 rad(Si)/s, so that even lower dose rates may be required to characterize their behavior for some applications. Modeling approaches for low dose rates are discussed, and linearity of the charge generation processes is shown to be an important factor in modeling. Interface state generation for one process was highly nonlinear, which reduced the impact of annealing and super recovery on device hardness.

Super recovery of the gate threshold voltage has been observed for several types of commercial NMOS integrated circuits. These devices have characteristic recovery times that are as much as four orders of magnitude shorter than those reported for hardened oxides. Since these fast recovery times are comparable to the irradiation times used in conventional total dose facilities, their failure levels are strongly affected by the dose rate used for testing. An empirical model has been developed that predicts the general features of super recovery, and can be used to calculate the dependence of circuit failure levels on dose rate.

Very large annealing rates have been observed for total dose damage in a commercial microprocessor. The annealing behavior has a complex dependence on bias conditions and dose rate, and persists for time periods in excess of 106 s. With positive bias applied, super recovery of the gate threshold voltage occurs so that the voltage shift at long times is opposite to that observed at short times afte...

Mechanisms are identified that can cause the transient response of digital logic circuits to depend on the logic state in which they are irradiated. Several of these mechanisms depend on surface topology, and for these cases the sensitive logic states can be determined by examining the topology. General approaches for transient radiation testing are also discussed for several MSI and LSI device technologies.

Methods are described for evaluating neutron damage in the types of operational amplifiers that are typically used in modern tactical systems. Critical electrical parameters are discussed, and the internal current sources are identified as important control parameters for hardness assurance. These current sources are more important than internal transistor gain in determining internal operating ma...