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At least 91 records · Page 5

Learning From Failure: Boosting Cycling Endurance of Optical Phase Change Materials

Chalcogenide phase change materials (PCMs) are a unique class of compounds whose switchable optical and electronic properties have fueled an explosion of emerging applications in microelectronics and microphotonics. Key to any application is the ability of PCMs to reliably switch between crystalline and amorphous states over a large number of cycles. While this issue has been extensively studied in the case of microelectronic memories, current PCM-based optical devices suffer from much inferior endurance. To understand the failure mechanisms limiting endurance of PCMs specifically in microphotonic devices, we have developed an on-chip resistive micro-heater platform and an automatic multi-modal characterization system to analyze cycling performance of optical PCMs. Reversible switching of large-area PCM devices over 50,000 cycles was demonstrated.

Optical phase change material↗

The efficacy of post porosity plasma protection against vacuum-ultraviolet damage in porous low-k materials

As of today, plasma damage remains as one of the main challenges to the reliable integration of porous low-k materials into microelectronic devices at the most aggressive node. One promising strategy to limit damage of porous low-k materials during plasma processing is an approach we refer to as post porosity plasma protection (P4). In this approach, the pores of the low-k material are filled with a sacrificial agent prior to any plasma treatment, greatly minimizing the total damage by limiting the physical interactions between plasma species and the low-k material. Interestingly, the contribution of the individual plasma species to the total plasma damage is not fully understood. In this study, we investigated the specific damaging effect of vacuum-ultraviolet (v-UV) photons on a highly porous, k = 2.0 low-k material and we assessed the P4 protective effect against them. It was found that the impact of the v-UV radiation varied depending upon the v-UV emission lines of the plasma. More importantly, we successfully demonstrated that the P4 process provides excellent protection against v-UV damage.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Mathematics of Gas Ingress of Hermetic Packages

Herein, we have derived a gas ingress and egress equation from the first principles of ideal gases. This work is intended to benefit the hermetic microelectronics packaging community, but it may be applied to other fields that require a deep understanding of gas ingress and egress dynamics. The equation outlined herein encompasses package material properties, package characteristics, hermetic testing conditions, and service conditions. It serves as a practical utility for calculating package pressure changes due to gas ingress and egress and, therefore, a power tool for component and system service life predictions.

42 ENGINEERING↗

Atoms-to-devices models for post-irradiation annealing kinetics in III-V semiconductors

Understanding atomic displacement damage and propagating this understanding into validated defect-aware radiation damage models is a critical step toward achieving predictive, atoms-to-systems assessment of radiation vulnerabilities of microelectronics. These models are essential for evaluating the performance and reliability of nuclear stockpile components or space-based electronics (satellites). The goal of this project was to bridge a fundamental science gap between defect spectroscopies and atomistic modeling of radiation-induced defects on the one hand, and simulations of device response on the other hand, to develop predictive defect-aware damage models for high-fidelity device simulations of radiation-damaged III-V semiconductors.

36 MATERIALS SCIENCE↗

Ultracompliant Heterogeneous Copper–Tin Nanowire Arrays Making a Supersolder

Due to the substantial increase in power density, thermal interface resistance that can constitute more than 50% of the total thermal resistance has generally become a bottleneck for thermal management in electronics. However, conventional thermal interface materials (TIMs) such as solder, epoxy, gel, and grease cannot fulfill the requirements of electronics for high-power and long-term operation. Here, we demonstrate a high-performance TIM consisting of a heterogeneous copper-tin nanowire array, which we term 'supersolder' to emulate the role of conventional solders in bonding various surfaces. The supersolder is ultracompliant with a shear modulus 2-3 orders of magnitude lower than traditional solders and can reduce the thermal resistance by two times as compared with the state-of-the-art TIMs. This supersolder also exhibits excellent long-term reliability with >1200 thermal cycles over a wide temperature range. By resolving this critical thermal bottleneck, the supersolder enables electronic systems, ranging from microelectronics and portable electronics to massive data centers, to operate at lower temperatures with higher power density and reliability.

36 MATERIALS SCIENCE↗

Advanced Power Electronics and Electric Machines

NLR's advanced power electronics and electric machines (APEEM) research group develops world-class experimental and modeling capabilities to design and evaluate efficient and reliable power electronics and electric machines, as well as innovative thermal management systems to maximize their performance. They also design, fabricate, and characterize advanced power electronics packaging and are developing state-of-health monitoring techniques.

25 ENERGY STORAGE↗

Commercial Parts Technology Qualification Processes

Many high-reliability systems, including space systems, use selected commercial parts (including Plastic Encapsulated Microelectronics or PEMs) for unique functionality, small size, low weight, high mechanical shock resistance, and other factors. Predominantly this usage is subjected to certain 100% tests (typically called screens) and certain destructive tests usually (but not always) performed on the flight lot (typically called qualification tests). Frequently used approaches include those documented in EEE-INST-002 and JPL DocID62212 (which are sometimes modified by the particular aerospace space systems manufacturer). In this study, approaches from these documents and several space systems manufacturers are compared to approaches from a launch systems manufacturer (SpaceX), an implantable medical electronics manufacturer (Medtronics), and a high-reliability transport system process (automotive systems). In the conclusions section, these processes are outlined for all of these cases and presented in tabular form. Then some simple comparisons are made. In this introduction section, the PEM technology qualification process is described, as documented in EEE-INST-002 (written by the Goddard Space Flight Center, GSFC), as well as the somewhat modified approach employed at the Jet Propulsion Laboratory (JPL). Approaches used at several major NASA contractors are also described

Cooper, Mark S.↗

A fifty channel electrically scanned pressure module

A unique miniature pressure sensor system consisting of an array of fifty integrated sensor pressure transducers with integral electronic logic and switching is described. Solid state processing of the piezoresistive array is combined with hybrid microelectronics to produce a very small, dense (80 cc displacement), high reliability pressure measuring system. Application to high speed data acquisition, energy conservation in wind tunnels and flight test is discussed. Test data are presented typifying system performance.

Mallon, J. R.↗

Standards for Epoxies Used in Microelectronics

Improved qualification standards and test procedures for epoxy adhesives used in assembly of high-reliability hybrid microcircuits listed in new report. Objective of standards to resolve problems in areas of outgassing, bond shear strength, corrosivity, volume resistivity, ionic impurities, electrical stability, and frequency of qualification testing. pp

Caruso, S. V.↗

Probing Plasticity and Strain-Rate Effects of Indium Submicron Pillars Using Synchrotron Laue X-ray Microdiffraction

We present that mechanical behaviors and especially the strain-rate responses at the nanoscales of low melting temperature metals, such as indium have not been much studied. Indium is one of the key materials or alloy-components in advanced microelectronics and nanotechnology industry, and understanding their mechanical behaviors at nanoscales becomes increasingly important to ensure lifetime reliability of their applications in novel nanoscale devices or advanced systems (for packaging at the nanoscales, for instance). Synchrotron X-ray microdiffraction has been utilized to examine defect structures of nanoscale materials as well as their strain-rate responses. Nanoscale or advanced microelectronics packaging, for instance, require acceptable levels of drop test results. For these low melting temperature materials especially, this technique offers a unique advantage as conventional methods such as TEM and EBSD will expose the structure to high energy electron beams that may significantly alter the microstructure and defect structure during analysis. Using this approach, we found interesting differences in term of X-ray peak broadening after deformation with different strain rates, which could indicate differences in plasticity mechanisms in the submicron pillars of indium, which could be important for its applications in nanodevices. Finally, understanding these differences could lead to better control of mechanical properties of low melting temperature metals at the nanoscales and thus have important implications for nanodevice reliability.

36 MATERIALS SCIENCE↗

Failure Analysis of Solder Joints

Soldering is a critical filler material joining process found in nearly all modern electronics. Ensuring solder joint reliability is crucial for the safety, performance, and cost-effectiveness of microelectronics.

42 ENGINEERING↗

Predictions for Radiation Shielding Materials

Radiation from galactic cosmic rays (GCR) and solar particle events (SPE) is a serious hazard to humans and electronic instruments during space travel, particularly on prolonged missions outside the Earth s magnetic fields. Galactic cosmic radiation (GCR) is composed of approx. 98% nucleons and approx. 2% electrons and positrons. Although cosmic ray heavy ions are 1-2% of the fluence, these energetic heavy nuclei (HZE) contribute 50% of the long-term dose. These unusually high specific ionizations pose a significant health hazard acting as carcinogens and also causing microelectronics damage inside spacecraft and high-flying aircraft. These HZE ions are of concern for radiation protection and radiation shielding technology, because gross rearrangements and mutations and deletions in DNA are expected. Calculations have shown that HZE particles have a strong preference for interaction with light nuclei. The best shield for this radiation would be liquid hydrogen, which is totally impractical. For this reason, hydrogen-containing polymers make the most effective practical shields. Shielding is required during missions in Earth orbit and possibly for frequent flying at high altitude because of the broad GCR spectrum and during a passage into deep space and LunarMars habitation because of the protracted exposure encountered on a long space mission. An additional hazard comes from solar particle events (SPEs) which are mostly energetic protons that can produce heavy ion secondaries as well as neutrons in materials. These events occur at unpredictable times and can deliver a potentially lethal dose within several hours to an unshielded human. Radiation protection for humans requires safety in short-term missions and maintaining career exposure limits within acceptable levels on future long-term exploration missions. The selection of shield materials can alter the protection of humans by an order of magnitude. If improperly selected, shielding materials can actually increase radiation damage due to penetration properties and nuclear fragmentation. Protecting space-borne microelectronics from single event upsets (SEUs) by transmitted radiation will benefit system reliability and system design cost by using optimal shield materials. Long-term missions on the surface of the Moon or Mars will require the construction of habitats to protect humans during their stay. One approach to the construction is to make structural materials from lunar or Martian regolith using a polymeric material as a binder. The hydrogen-containing polymers are considerably more effective for radiation protection than the regolith, but the combination minimizes the amount of polymer to be transported. We have made composites of simulated lunar regolith with two different polymers, LaRC-SI, a high-performance polyimide thermoset, and polyethylene, a thermoplastic.

Kiefer, Richard L.↗

Microelectronic DNA assay for the detection of BRCA1 gene mutations

Mutations in BRCA1 are characterized by predisposition to breast cancer, ovarian cancer and prostate cancer as well as colon cancer. Prognosis for this cancer survival depends upon the stage at which cancer is diagnosed. Reliable and rapid mutation detection is crucial for the early diagnosis and treatment. We developed an electronic assay for the detection of a representative single nucleotide polymorphism (SNP), deletion and insertion in BRCA1 gene by the microelectronics microarray instrumentation. The assay is rapid, and it takes 30 minutes for the immobilization of target DNA samples, hybridization, washing and readout. The assay is multiplexing since it is carried out at the same temperature and buffer conditions for each step. The assay is also highly specific, as the signal-to-noise ratio is much larger than recommended value (72.86 to 321.05 vs. 5) for homozygotes genotyping, and signal ratio close to the perfect value 1 for heterozygotes genotyping (1.04).

Validation Studies↗

A production parylene coating process for hybrid microcircuits

The real impetus for developing a production parylene coating process for internal hybrid passivation came as a result of the possibility of loose conductive particles in hybrid microelectronic circuits, causing intermittent and sometimes permanent failures. Because of the excellent mechanical properties of parylene, it is capable of securing the loose particles in place and prevent such failures. The process of coating described consists of (1) vaporizing the initial charge, which is in the form of a dimer; (2) conversion of the dimer into a reactive monomer; and (3) deposition and subsequent polymerization of the monomer in the deposition chamber which forms a uniform parylene film over all the cold surfaces in contact. Experimental results are discussed in terms of wire bond reliability, resistor drift, high-temperature storage characteristics of parylene, and coating acceptance standards. It is concluded that internal cavities of microelectronic circuits can be successfully coated with parylene provided appropriate tooling is used to protect external leads from the parylene monomer.

Kale, V. S.↗