Search

We have developed silicon epitaxial wafers with high gettering capability using hydrocarbon molecular ion implantation for advanced Complementary Metal-Oxide-Semiconductor (CMOS) image sensors. These wafers have three unique silicon wafer characteristics for improvement of CMOS device electrical parameter such as high metallic impurity gettering, oxygen out-diffusion barrier effects from Czochralski silicon (CZ) substrate and hydrogen passivation effect for interface state defect at Si/SiO2. We demonstrate that double epitaxial growth silicon wafers have an extremely high gettering capability during CMOS device fabrication process. We also found that gettering capability strongly dependence on oxygen impurity amount in hydrocarbon molecular ion implantation projection range. We believe that this novel silicon wafer can drastically contribute to the improvement of CMOS image sensor device performance such as white spot defect and dark current.

We discuss the needs and challenges of deployable security research by sharing our experience designing CryptoGuard, a high-precision tool for detecting cryptographic application programming interface misuses. Our project has produced multiple benchmarks as well as measurement results on state-of-the-art solutions. [ABSTRACT FROM AUTHOR]

Hermetic sealing microelectronic devices in package become more and more of a challenge for manufacturers due to the complexity of thermal management, getter integration, and material selection and interactions. Such complexity drives the original equipment manufacturer (OEM) to deliver the equipment and technology to meet manufacturers’ requirements. This study has successfully demonstrated that a vacuum reflow technology is able to deliver packages with an excellent hermetic seal. The measured leak rates of these two package types are about two orders of magnitude better than the requirement by Mil-Std 883 method 1014 specification. The result is clear that optimization of the force applied to the lid and package during seal process is essential and the force density of 5 kPa is able to produce a great hermeticity for the two packages under study. A good solder joint strength is essential to deliver a package with hermeticity but is not enough, while a weak joint strength is not possible to achieve hermeticity. [ABSTRACT FROM AUTHOR]

Thispaper introduces a novel, inherently simple, and all-silicon wafer-level fabrication and hermetic packaging method developed for MEMS devices. The proposed method uses two separate SOI wafers to form highly-doped through-silicon vias (TSVs) and suspended MEMS structures, respectively. These SOI wafers are then bonded by Au-Si eutectic bonding at 400 °C, achieving hermetic sealing and signal transfer without requiring any complex via or trench refill process steps. The package vacuum is measured using encapsulated MEMS resonators to be as low as 15 mTorr with the help of successfully activated thin-film getters. The combined fabrication and packaging yield is around %89 and chips still maintain a package pressure below 100 mTorr after more than 6 years. The packages show an extremely high strong bonding strength (>40 MPa) and are proved to remain hermetic after temperature cycling (25 °C-85 °C) and harsh temperature shock (5 min@300 °C) tests. The all-silicon MEMS resonators fabricated and packaged using the proposed method project up to a $2.3\times $ enhancement in the bias instability and $\sim 4\times $ in the temperature sensitivity of frequency output compared to an identical MEMS resonator fabricated using the silicon-on-glass (SOG) technology. [ABSTRACT FROM AUTHOR]

Gettering sinks for metallic impurities formed by carbon-cluster ion implantation in epitaxial silicon wafers have been investigated using technology computer-aided design and atom probe tomography (APT). We found that the defects formed by carbon-cluster ion implantation consist of carbon and interstitial silicon clusters (carbon-interstitial clusters). Vacancy-type clusters are not dominant gettering sinks for metallic impurities in the carbon-cluster ion implanted region. APT data indicated that the distribution of oxygen atoms in the defects differs between Czochralski-grown silicon and epitaxial silicon wafers. The high gettering efficiency observed in carbon-cluster ion implanted epitaxial silicon wafers in comparison with Czochralski-grown silicon wafers is due to the distribution of oxygen atoms in the defects. Defects not containing O atoms provide strong gettering sinks for metallic impurities. These defects are formed by only carbon-interstitial clusters. Oxygen atoms inside the defects modify the amount of carbon-interstitial cluster formation on the defects. It is suggested that the gettering efficiency for metallic impurities in carbon-cluster ion implanted epitaxial silicon wafer is determined by the amount of carbon-interstitial clusters.

Presence of a native oxide interlayer degrades seriously the contact resistivity ($\rho _{{\text {c}}}$) of co-deposited TiSi (CD-TiSi) on Si:P. The oxide cannot be scavenged by the CD-TSi due to its low solid solubility of O. We tackle the problem by capping the CD-TiSi with an O gettering cap. Utilizing a Ti cap and two-step post-metal rapid thermal anneal, we reduce the $\rho _{{\text {c}}}$ of the CD-TiSi on ${2}\times {10}^{{21}}$ cm $^{-{3}}$ doped Si:P by ${\sim }{3}$ times, down to ${\sim }{2} \times {10}^{-{9}}\,\,\Omega \cdot \text {cm}^{{2}}$. We also demonstrate efficiency of a La cap to scavenge the oxide. [ABSTRACT FROM AUTHOR]

Due to the impact of arcing on high-purity surfaces and bound residual gases, current interruption operations may influence the internal pressure in vacuum interrupters (VIs). In this paper, we investigate the temporal development of internal pressure in VIs immediately after a current interruption operation, both intrusively using a vacuum gauge and nonintrusively using the magnetron method. By means of an experimental test setup that consists of a vacuum test system to vary the internal pressure in punctured, nonvented VIs with active getter elements, we performed experimental test series under variation of internal pressure and arcing time. The experimental results indicate that arcing during the interruption operation predominantly causes a significant decrease in the internal pressure of up to several orders of magnitude, depending on the arcing time and the initial pressure before the current interruption operation. Based on a test series with passivated getter elements, we found that active getter elements have only a minor influence on the observed pressure decrease. With regard to a condition assessment of vacuum circuit breakers, we discuss the impact of the observed pressure reduction effect on the possibility of predicting the remaining service life of installed VIs. [ABSTRACT FROM PUBLISHER]

Si CMOS image-sensor (CIS) cells were designed by implementing proximity relaxation gettering sites of hydrogen-ion implantation-induced nanocavities (20–35 nm in diameter) underneath Si photodiode regions to enhance the sensing margin of output voltage in CIS cells. They enabled almost no degradation in the output voltage sensing margin, although ~ $ 10^{{\mathsf {14}}}$ cm $^{{\mathsf {-2}}}$ of Fe, Cu, Ni, and Co contaminants were introduced in the photodiode regions of CIS cells, demonstrating an excellent relaxation gettering ability. However, Si CIS cells designed with p/p++ epitaxial wafers, which are widely used, showed that the sensing margin of the CIS cells significantly decreased as the concentration of Cu and Ni contaminants in the Si photodiode regions increased, indicating no segregation gettering ability. [ABSTRACT FROM PUBLISHER]

Recently, room temperature trapped ion atomic clock development at the Jet Propulsion Laboratory (JPL) has focused on three directions: 1) ultrastable atomic clocks, usually for terrestrial applications emphasizing ultimate stability performance and autonomous timekeeping; 2) new atomic clock technology for space flight applications that require strict adherence to size, weight, and power requirements; and 3) miniature clocks. In this paper, we concentrate on the first direction and present a design and the initial results from a new ultrastable clock referred to as L10 that achieves a short-term stability of 4.5 \times 10^\mathrm -14/\tau ^\mathrm 1/2 and an initial measurement of no significant drift with an uncertainty of 2.4 \times 10^\mathrm -16 /day over a two-week period. [ABSTRACT FROM PUBLISHER]

This paper reported the IGZO and IZO thin-film transistor (TFT) with titanium-oxide semiconductor as channel capping layer. After the \TiOx Gettering process, the oxygen vacancies in IGZO channel were successfully modified to maximize the carrier concentration and device mobility. The superior transfer characteristics included a low sub-threshold swing of 79 mV/decade, a very high mobility of \68~\cm^2/\V\cdot\s, and good on/off-current ratio of \5.61\times \10^6. However, the IZO channel with nano-crystallized grains and without Ga atom doping showed unfavorable transistor characteristics. In addition to apparently degraded transfer properties, the spontaneously oxidized \TiOx capping layer also lead to an increase of channel parasitic resistance that limits the output driving current. Therefore, we believe that the existence of Ga–O bonds among IGZO channel would be helpful to stabilize oxygen diffusion behavior and electric structure during Gettering process. [ABSTRACT FROM PUBLISHER]

Consecutive absorption/desorption cycles of the ZrCo–H2 system were studied to simulate the real International Thermonuclear Experimental Reactor (ITER) hydrogen getter system. A ZrCo getter was used in this paper instead of the depleted uranium (DU) getter material, which has been recently considered as the hydrogen getter in ITER. In a cyclic pressure-composition isotherm (PCI) measurement, the high-pressure Sievert apparatus seems impractical to describe the equilibrium state of the ZrCo–H2 system in detail, especially for the desorption stage. This high-pressure PCI apparatus, however, shows cause and effect well, from the previous getter state to the following state in presenting hydriding/dehydriding performance. In case of the ZrCo–H2 system or in case of the DU–H2 system having multiple getter bed battery, a similar affection by previous getter status might be related and a similar aspect could be shown to consider further ITER design; for example, a need for control logic from PCI measurements using a high-pressure Sievert apparatus. [ABSTRACT FROM PUBLISHER]

This paper reports a novel and inherently simple fabrication process, so-called advanced MEMS (aMEMS) process, that is developed for high-yield and reliable manufacturing of wafer-level hermetic encapsulated MEMS devices. The process enables lead transfer using vertical feedthroughs formed on an Silicon-On-Insulator (SOI) wafer without requiring any complex via-refill or trench-refill processes. It requires only seven masks to fabricate the hermetically capped sensors with an experimentally verified process yield of above 80%. Hermetic encapsulation is achieved by Au–Si eutectic bonding at 400 °C, and the pressure inside the encapsulated cavity has been characterized to be as low as 1 mTorr with successfully activated thin-film getters. The pressure inside the encapsulated cavity can also be adjusted in the range of 1 mTorr-5 Torr by various combinations of outgassing and gettering options in order to satisfy the requirements of different applications. The package pressure is being monitored for the selected chips and is observed to be stable below 10 mTorr since their fabrication about 10 months ago. The shear strengths of several packages are measured to be as high as 30 MPa with average shear strength of 22 MPa, indicating a mechanically strong bonding. The robustness of the packages is tested by thermal cycling between 100 °C and 25 °C, and absolutely no degradation is observed in the hermeticity and the package pressure. The package pressure is also verified to remain unchanged after storing the packages at a high storage temperature of 150 °C for 24 h. Furthermore, the packaged chips are observed to withstand a high temperature shock test performed at 300 °C for 5 min, at the end of which the characteristics of the encapsulated sensor indicates that the package still remains hermetic (no detectable leaks) and also the package pressure remains constant at $\sim 20$ mTorr. [2014-0338] [ABSTRACT FROM AUTHOR]

This study involved developing a low-power and high-mobility metal–oxide thin-film transistor that incorporated a bilayer IGZO/IGZO:Ti semiconductor material. Compared with control metal–oxide TFTs, the bilayer IGZO TFT through thickness modulation of IGZO:Ti can reach the smallest subthreshold swing (85 mV/decade) and the highest field effect mobility (49 cm2/Vs) at a drive voltage of <3 V. This performance level improvement can be attributed to the gettering effect caused by the IGZO:Ti capping layer and its dual advantages, which enhance device mobility and improve gate swing. [ABSTRACT FROM PUBLISHER]

The microengineered MEMS-type ion-sorption micropump with field-emission electron source has been shown. Effective emission properties of the carbon nanotubes cathode ensure satisfactory efficiency of residual gas ionization, showing possibility of active pumping of circa 0.05 cm3 volume down to 10-5 hPa. Measurement of ion current allows estimation of vacuum level inside the microcavity. [ABSTRACT FROM AUTHOR]

Lighting is responsible for the consumption of more than 2650 TWh of energy per year, corresponding to about 20\% of the global electricity consumption. All the strategies and international policies pushing for the adoption of more efficient light sources are assuming a real important role for energy saving and for the reduction of greenhouse gas emissions. This paper will illustrate technological approaches that can contribute at improving the performance of low-pressure mercury lamps and high-intensity-discharge lamps. Advancements and optimization of materials, such as getters, active amalgams, and starting amalgams, can allow to produce light sources with superior characteristics. Concerning the aspect related to innovative materials, it is worth underlining that many of the fluorescent lamps today available on the market are using advanced technological solutions based on stable mercury compounds for accurate and reliable Hg dosing, down to very low levels. [ABSTRACT FROM PUBLISHER]

Radiochemical diagnostic techniques such as solid- and gas-phase capsule debris analysis may prove to be successful methods for establishing the success or failure of ignition experiments at the National Ignition Facility (NIF). Samples in the gas phase offer the most direct method of collection by simply pumping out the large target chamber following a NIF shot. The target capsules will be prepared with dopants, which will produce radioactive noble-gas isotopes upon activation with neutrons or charged particles. We have designed and constructed the Radchem Apparatus for Gas Sampling (RAGS) in order to collect postshot gaseous samples for NIF capsule diagnostics. The design of RAGS incorporates multiple stages intended to cryogenically purify, transfer, and count the radioactive decays from gaseous products synthesized in NIF experiments. An implementation timeline at NIF is discussed. [ABSTRACT FROM AUTHOR]

This paper reports on the characteristics of a spin-on dielectric which has been used as the rear-surface passivation layer to achieve 20% efficient screen-printed (SP) boron back-surface field (B-BSF) solar cells. The dielectric provides, in a single thermal step, both stable passivation of a heavily doped \p^+ surface and strong gettering of iron which is a common contaminant in high-temperature boron diffusion processes. It was found that gettering of silicon substrates, contaminated during boron diffusion, is most effective when the dielectric is deposited on top of the boron-doped layer. The effect of dielectric charge density on passivation of \p^+ surfaces was also studied and a very high charge density of - \10^13\ \cm^-2 was found to be necessary to significantly improve the passivation on surfaces with a boron concentration > \10^19\ \cm^-3. [ABSTRACT FROM PUBLISHER]

Ni-metal-induced lateral crystallization (NILC) of amorphous silicon (α-Si) has been employed to fabricate polycrystalline silicon (poly-Si) thin-film transistors. However, current crystallization technology often leads to Ni and NiSi2 precipitates being trapped, thus degrading the performance of the device. We proposed using α-Si-coated wafers as Ni-gettering substrates. After bonding the gettering substrate with the NILC poly-Si film, both the Ni-metal impurity within the NILC poly-Si film and the leakage current were greatly reduced, thus increasing the ON/OFF current ratio. [ABSTRACT FROM AUTHOR]

We report a high performance indium-gallium-zinc oxide (IGZO)/IGZO:Ti bilayer metal–oxide thin-film transistor (TFT) with a low drive voltage of <2~V. Compared with conventional IGZO TFTs, the novel bilayer metal–oxide TFTs through IGZO thickness modulation can reach the lowest off current of 1.6\times 10^-11~A, smallest sub-threshold swing of 73 mV/decade, and highest mobility of 63 cm^2/Vs, which may create the potential application for high resolution display. [ABSTRACT FROM AUTHOR]

We observe a trend between initial leakage currents in polycrystalline HfOx resisitive random access memory (RRAM) cells (before forming) and the forming voltages. This trend points to the dominant role played by conduction paths located at grain boundaries, which is promoted by the oxygen deficiency in HfOx. One of these paths is then converted into the conductive filament responsible for nonvolatile resistance switching. In addition, we find that by engineering the RRAM stack, the forming voltage can be tuned-up to meet specific RRAM requirements, such as lower power and forming-less operations. [ABSTRACT FROM AUTHOR]

Polycrystalline silicon thin-film transistors (TFTs) fabricated by seed-induced crystallization (SIC) have large leakage currents due to defects that consist of Ni impurities. Here, we describe a novel method of gettering to remove Ni impurities using a Si gettering layer that is separated from the active layer by a chemical \SiO2 etch stop interlayer formed by dipping into \H2\SO4. The leakage current, the on/off ratio, and a channel breakdown voltage were greatly improved. These results were explained by lowered trap-state density in the channel. [ABSTRACT FROM AUTHOR]

Ion diffusion and gettering in YBCO oxides were studied, The experiment was carried out by implanting Si or Ni ions into epitaxial YBCO films and subsequently annealing the samples at different temperatures ranging from 450/spl deg/C to 1050/spl deg/C. Secondary ion mass spectroscopy (SIMS) analysis was used to determine ion profiles. At an annealing temperature of 750/spl deg/C, the silicon ions started to getter towards the peak of the silicon concentration, which has the maximum concentration. This gettering process continued annealing temperature was increased and reached the maximum at 850/spl deg/C. Further increases in annealing temperatures caused the ions to outdiffuse and intermix with YBCO. In contrast, nickel ions do not show gettering effect, rather they outdiffuse after annealing. The crystal damage caused by the implantation and chemical reaction between implanted ions and target material seemed to be the main reason of this gettering effect. [ABSTRACT FROM PUBLISHER]

Bad smells are signs of potential problems in code. Detecting and resolving bad smells, however, remain time-consuming for software engineers despite proposals on bad smell detection and refactoring tools. Numerous bad smells have been recognized, yet the sequences in which the detection and resolution of different kinds of bad smells are performed are rarely discussed because software engineers do not know how to optimize sequences or determine the benefits of an optimal sequence. To this end, we propose a detection and resolution sequence for different kinds of bad smells to simplify their detection and resolution. We highlight the necessity of managing bad smell resolution sequences with a motivating example, and recommend a suitable sequence for commonly occurring bad smells. We evaluate this recommendation on two nontrivial open source applications, and the evaluation results suggest that a significant reduction in effort ranging from 17.64 to 20 percent can be achieved when bad smells are detected and resolved using the proposed sequence. [ABSTRACT FROM AUTHOR]