Philippe C. Adell

Mechanisms of Enhanced Radiation-Induced Degradation Due to Excess Molecular Hydrogen in Bipolar Oxides

Bipolar junction test structures packaged in hermetically sealed packages with excess molecular hydrogen (H2) showed enhanced degradation after radiation exposure. Using chemical kinetics, we propose a model that quantitatively establishes the relationship between excess H2 and radiation-induced interface trap formation. Using environments with different molecular hydrogen concentrations, radiation experiments were performed and the experimental data showed excellent agreement with the proposed model. The results, both experimentally and theoretically, showed increased radiation induced degradation with H2 concentration, and device degradation saturate at both high and low ends of H2 concentrations.

Assessing and mitigating radiation effects in Xilinx SRAM FPGAs

This work intends to help designers assess and mitigate radiation effects in systems that use SRAM-based FPGAs. Several methodologies combining experimental procedure, mitigation strategies and technical aspects are discussed.

The Effects of Hydrogen in Hermetically Sealed Packages on the Total Dose and Dose Rate Response of Bipolar Linear Circuits

It is demonstrated with test transistors and circuits that a small amount of hydrogen trapped in hermetically sealed packages can significantly degrade the total dose and dose rate response of bipolar linear microelectronics. In addition, we show that when exposed to an atmosphere of 100% molecular hydrogen dies with silicon nitride passivation are unaffected, whereas dies with silicon carbide or deposited oxides become very soft at high and low dose rate.

Radiation Effects in Power Systems: A Review

To guarantee mission success and minimize the risk of anomalies in space, current space-power architectures are designed conservatively and use electronics that are several generations behind the current state of the art. In parallel, the commercial industry is burgeoning with exciting new solutions for power management; however, their reliability and radiation robustness for space application have yet to be proven. The goal of this paper is to review common radiation issues related to power converters, which are the main design blocks of current space power system architectures. We first provide some background material and introduce the basic principles of power converter operation, as well as a brief introduction of common radiation effect that might damage these designs. Then, we explain common radiation-induced failure mechanisms (radiation-induced failure or instability) or temporary perturbations observed in various converter topologies. Their radiation hardness is compared based on simulation and experimental studies reported in the literature. Some radiation hardening by design solutions and mitigation techniques are also presented. Finally, we provide a status of emerging technologies under consideration for the next-generation of space power systems.

Modeling the Radiation Response of Fully-Depleted SOI n-Channel MOSFETs

A continuous analytical model for radiation-induced degradation in fully-depleted (FD) silicon on insulator (SOI) n-channel MOSFETs is presented. The combined effects of defect buildup in the buried oxide and band-to-band tunneling (BBT) have been shown to be the primary mechanisms that determine the radiation effects on the electrical characteristics. Closed-form expressions for the front and back-gate surface potential incorporate these effects, thereby enabling accurate modeling of the degraded current voltage characteristics that result from ionizing radiation exposure.

Irradiation With Molecular Hydrogen as an Accelerated Total Dose Hardness Assurance Test Method for Bipolar Linear Circuits

High dose rate irradiation with hydrogen stress is proposed as an accelerated total dose test method for bipolar linear circuits. The method is validated across process and circuit technologies with five parts that are commonly used in space: a comparator (LM193 from National Semiconductor), a voltage regulator (HSYE-117 RH from Intersil), a voltage reference (LT1019 from Linear Technology), a JFET input op amp (OP42 from Analog Devices) and a temperature transducer (AD590 from Analog Devices). The testing technique could rapidly establish an upper bound to the low dose rate response of parts in space and help with the part selection process in the design phase of a mission. Radiation hardness assurance implications are discussed.

Investigation of Single-Event Transients in Linear Voltage Regulators

Single-event transients (SETs) from heavy ions and laser beam are investigated for two positive adjustable linear voltage regulators: the RH117 from linear technology and the HS-117RH from Intersil. Both positive and negative going transients are observed. The role of input voltage, load capacitance and supply current on the SET response is discussed.

Impact of VCO Topology on SET Induced Frequency Response

Laser experiments performed on two SiGe voltage controlled oscillator (VCO) circuit topologies show different output spectrums. Analytical models demonstrate that spectral response is determined by design features that impact modulated amplitude or frequency characteristic of transient signals. Further analysis of the two circuits shows the DC bias condition dependence on the topology during laser strikes, which is the main cause of the frequency and amplitude modulation of the transient output signal.

Single-Event Transient Testing of Low Dropout PNP Series Linear Voltage Regulators

Recommendations are provided for Single Event Transient (SET) testing of low dropout (LDO) PNP series linear voltage regulators. A combination of SPICE circuit simulations and pulsed laser irradiations are used to demonstrate that the equivalent series resistance (ESR), loading conditions and regulator stability are the key elements that govern LDO regulators SET response. Pulsed laser testing of several light-like candidates shows similar SET trends and dependences. Due to the additional circuits introduced in an LDO design, we reveal the existence of a thermal shutdown mode that can be triggered by a single event that is also load dependent.

Modeling Low Dose Rate Effects in Shallow Trench Isolation Oxides

Low dose rate experiments on field-oxide-field-effect-transistors (FOXFETs) fabricated in a 90 nm CMOS technology indicate that there is a dose rate enhancement factor (EF) associated with radiation-induced degradation. One dimensional (1-D) numerical calculations are used to investigate the key mechanisms responsible for the dose rate dependent buildup of radiation-induced defects in shallow trench isolation (STI) oxides. Calculations of damage EF indicate that oxide thickness, distribution of hole traps and hole capture cross-section affect dose rate sensitivity. The dose rate sensitivity of STI oxides is compared with the sensitivity of bipolar base oxides using model calculations.