bluuebunny/crossref_metadata_2025 huggingface dataset:
HIGH TEMPERATURE ULTRA HIGH VOLTAGE SIC THYRISTORS
Authors: Singh R. , Creamer S. , Lieser E. , Jeliazkov S. , Sundaresan S.
Published: October 2015

Through a systematic study, Silicon Carbide Gate Turn Off (GTO) Thyristors with record performance are demonstrated. Several Anode-Gate interdigitation schemes (raster, hex and involute) were explored to investigate their effect on the static as well as switching characteristics. An optimized edge-termination was employed that resulted in the achievement of near-theoretical forward blocking voltages (>8.1kV), and high yields (>60% on 8mm×8mm) on GTO Thyristors with 60μm/5×1014 cm−3 voltage-blocking epitaxial layers. A low differential specific on-resistance of 2.55 mΩ-cm2, and low on-state voltage drop were measured at 500 A/cm2. High Temperature forward I-V and reverse I-V characteristics show extremely stable performance with temperature, in contrast to state-of-the-art Si GTO Thyristors. Turn-on transient characteristics show a stable delay time of about 400 nano-seconds, and a rise-time that decreases with increasing temperature. Detailed high temperature turn-off measurements conducted using Anode-Switched mode was used to extract the value of minority carrier lifetimes as a function of temperature for the first time.
Metallurgy for SiC Die Attach for Operation at 500°C
Authors: Zheng Ping , Henson Phillip , Johnson R. Wayne , Chen Liangyu
Published: October 2015

Metallurgy for high temperature SiC die attach involves the substrate metallization, die metallization, and die attach material. This paper examines off-eutectic Au-Sn as the die attach alloy with a PtAu thick film metallization on AlN substrates. A pure Au thick film layer was printed over the PtAu thick film layer. The SiC backside metallizations evaluated were Ti/TaSi/Pt/Au and Cr/NiCr/Au. Die shear tests were performed after aging at 500°C and after thermal cycling. The shear test results and failure surface analysis are discussed.

Nanoparticle Ag and liquid transient phase bonding with Ag based metallurgies have been proposed for high temperature die attach. Data on the migration of sintered nano-particle Ag and thin film Ag dc bias during storage in air at 300°C and 375°C are presented. Migration of Ag is a potential failure mechanism for Ag based high temperature metallurgies.
Characterization of Thick Film Technology for 300°C Packaging
Authors: Zhang Rui , Johnson R. Wayne , Tilak Vinayak , Zhang Tan , Shaddock David
Published: October 2015

Geothermal well logging and instrumentation applications require electronics capable of 300°C operation. SiC device technology enables the design and fabrication of analog circuits that can operate at these temperatures. However, to build functional circuits, an interconnection and packaging technology must be demonstrated to provide interconnectivity between different SiC devices and passive components. For long-term operation, organic based packaging is limited to ∼250°C with careful selection of materials. Thick film technology based on ceramics and metals has potential for higher operating temperatures. In this work the effect of 300°C storage on the adhesion of different thick film Au conductors and a multilayer dielectric have been studied. In addition, the electrical properties of the dielectric have been studied as a function of temperature and of high temperature aging. Assembly technologies: component attach, wire bonding and external lead attach have also been investigated and the results are reported.
Assessment of Au-Ge Die Attachment for an Extended Junction Temperature Range in Power Applications
Authors: Tanimoto Satoshi , Matsui Kohei , Murakami Yoshinori , Yamaguchi Hiroshi , Okumura Hajime
Published: October 2015

A eutectic Au-Ge (12 wt%) die attach system has traditionally been used in electrical characterization of SiC devices in a temperature range up to 300°C. However, only fragmentary results have been reported concerning the applicability of the system. In this paper, a eutectic Au-Ge die attach system composed of 0.3-mm-thick, 2×2 mm2 SiC dies soldered on ceramic (SiN) substrates with Ni/Au-plated Cu foil is systematically discussed on the basis of the results of storage tests at 300°C and thermal cycle tests ranging from −40°C to 300°C. Die attachments were performed at ~400°C by using a vacuum reflow soldering system. Shear testing of the samples indicated that the initial dies had very strong shear strength of more than 100 MPa. After 300°C storage for 3000 hours in air, it was found that their shear strength markedly dropped, but still maintained an average value two times larger than the JAITA standard of 6.2 MPa specified in IEC 749 for die shear strength. The test results for a thermal cycle from −40°C to 300°C showed that although the shear strength of the samples gradually declined with an increasing number of cycles, it was still 10 MPa on average even after 2000 cycles.
A 200 °C Quad-Output Buck Type Switched Mode Power Supply IC
Authors: Goff Daniel T. , Majerus Steve J. A. , Merrill Walter
Published: October 2015

A high temperature (>200 °C), quad-output, buck type switched-mode power supply (SMPS) IC capable of operating over a wide input supply range of 6 V to 15 V is described. The IC is a compact power supply solution for multi-voltage microprocessors, sensors, and actuators. The SMPS topology is a 112 kHz fixed-frequency, synchronous buck converter with slope compensation. A novel internal feedback design enables the output voltages to be pin-programmed to one of three common supply voltages—5 V, 3.3 V, or 1.8 V—while an external resistor divider can also be used for arbitrary voltage programming. Integrated power supply output MOSFET switches minimize the external part count and synchronous rectification reduces power dissipation and improves current capacity. The IC was fabricated in a conventional, low-cost, 0.5 μm bulk CMOS foundry process. Patented circuit design techniques allow the IC to operate in excess of 200 °C and circuit operation was demonstrated at ambient temperatures up to 225 °C. The foundry process is optimized for 5 V applications, however, the IC accepts input voltages up to 15 V and can produce outputs up to 10 V by utilizing extended drain single- and double-sided NMOS and PMOS transistors for the linear regulator pass transistor, error amplifier, and SMPS switches. The high-side FETs are controlled through capacitive coupled level shift circuits to ensure the gate-oxide voltage limits are not exceeded while still maintaining fast signal transitions. The IC also includes a tunable, 25 MHz monolithic oscillator that is programmable over a SPI serial interface. The oscillator bias current is comprised of a programmable constant-gm bias current and a programmable PTAT bias current. The programmability can be used to set the oscillation frequency, but can also be used together with a calibration curve on a microcontroller to achieve a more stable oscillation frequency over temperature. The output current of the quad SMPS was limited to 70 mA by a lower than expected saturation current of the extended-drain PMOS switch devices. The system showed good line regulation (<0.1%) and 50% load step response stability (+/− 100 mV) at a nominal output current of 50 mA when tested at 200 °C ambient.
Strength and Reliability of High Temperature Transient Liquid Phase Sintered Joints
Authors: Moeini S. Ali , Greve Hannes , McCluskey F. Patrick
Published: October 2015

Low-temperature transient liquid phase sintering (LT-TLPS) can be used to form high-temperature joints between metallic interfaces at low process temperatures. In this paper, we will describe the processing and shear strength, along with the shock fatigue resistance of sintered joints made by this process. Joints made from different ratios of Ni and Cu high melting temperature constituents paired with Sn-based low melting temperature constituents have been evaluated. For the shear studies, the softening behavior of test samples joined by Ni-Sn3.5Ag and (Ni,Cu)-Sn3.5Ag sinter pastes have been assessed using a fixture designed for high temperature shear testing up to 600°C. The reliability of sinter paste joints in drop-shock environments will be discussed. It is shown that joints formed from these sinter pastes possess improved drop-shock reliability compared to Sn3.5Ag solder joints and melting temperatures considerably higher than those of conventional high temperature solders (e.g. Pb5.0Sn2.5Ag).
Recent Progress in Thin Film Multichip Packaging for High Temperature Digital Electronics
Authors: Fang Kun , Isaacs-Smith Tami , Johnson R. Wayne , Vert Alexey , Zhang Tan , Shaddock David
Published: October 2015

A thin film material and process technology is being developed and evaluated for high temperature (300°C) digital multichip modules for use in geothermal well instrumentation. The substrate technology selected is AlN to minimize the difference in the coefficient of thermal expansion between the substrate and the SiC digital die. A thin film/plated Ti/Ti:W/Au metallization is used with a plasma enhanced chemical vapor deposited Si3N4 to create multilayer interconnections. Active components are assembled to the interconnect substrate using Au stud bump thermocompression bonding. The Au stud bump maintains a monometallic interface between the substrate Au pad surface and the Au pads on the SiC die. A digital circuit has been built and successfully tested as an initial demonstration.
Analog and Logic High Temperature Integrated Circuits based on SiC JFETs
Authors: Alexandrov Peter , Li Xueqing , O'Grady Matt , Hostetler John
Published: October 2015

Harsh environment applications such as electrical actuation on military and commercial aircraft, advanced engine controls, downhole energy exploration, propulsion systems of hybrid and all electric vehicles, and space exploration require sensor interfaces, control circuits, and power systems with electronics capable of operating at high temperatures. Wide band-gap materials such as SiC can be used to build devices with high operating temperatures due to their fundamental material properties. This paper presents initial results on developing basic analog and logic integrated circuits based on SiC JFET technology. Analog and logic integrated circuits were built using enhancement vertical channel lateral JFET transistors, metal film resistors and lateral p-n diodes. The analog circuits built include different types of operational amplifiers. The logic circuits include NOT, NAND, AND, NOR and OR gates. Transistors and integrated circuits were packaged in ceramic DIP packages and tested at temperatures up to 500 °C. The tested JFETs show proper operation up to the maximum tested temperature of 500 °C. The operational amplifiers remained functional at temperatures up to 430 °C. Basic logic circuits showed proper operation up to the maximum tested temperature of 500 °C.
Experimental results of testing high-temperature-high-current pulsed operation of SiC MOSETs and SiC diodes
Authors: Morris Steven A. , Zhao Ruichen , Krugliak Zinovy
Published: October 2015

Using hot plate experiments testing to a maximum temperature of 200 °C, we performed tests to determine the maximum single pulse current allowable for Cree CMF20120D SiC MOSFETs and Cree C4D40120D Schottky diodes. Using single pulse switching of a resonant circuit, a half-sine shaped current pulse of 5∼10 μsec duration was used to test the devices. A criterion for maximum allowable peak current was determined from the point of dramatic increase in conduction loss as a function of peak current. At 200 °C, maximum single pulse current was found to be 200 amp for the SiC MOSFET and about 500 amp for the SiC Schottky diode (both legs in parallel). We also report measurements of leakage current on the devices as a function of temperature, and will present measurements on an IGBT device of comparable current rating for comparison. Simple measurements of this type are a useful way of determining operational limits of SiC devices at temperatures that are not reported in the device data sheet.
500 kHz – 5 MHz Phase-Locked Loops in High-Temperature Silicon Carbide CMOS
Authors: Shepherd Paul , Rahman Ashfaqur , Ahmed Shamim , Francis A Matt , Holmes Jim , Mantooth H. Alan
Published: October 2015

Silicon Carbide (SiC) integrated circuits processes show promise for improved performance in high temperature, high radiation, and other extreme environments. The circuits described are the first implementations of phase-locked or delay-locked loops in SiC. The PLL utilizes a common charge-pump topology including a fully integrated passive loop filter, and were designed with a target maximum operating frequency of 5 MHz. Component blocks use novel topologies to optimize performance in a SiC CMOS process. Experimental results of both the complete PLL as well as the Phase Frequency Detector and Voltage Controlled Oscillator components are presented. Operation of the PLL at frequencies up to 1.5 MHz is demonstrated through test results of unpackaged die.
500 °C operation of AlGaN/GaN and AlInN/GaN Integrated Circuits
Authors: Gaevski Mikhail , Deng Jianyu , Simin Grigory , Gaska Remis
Published: October 2015

High-temperature technology platform has been developed utilizing planar III-nitride heterostructures approach. The record high electron concentration and mobility in 2DEG channel of III-nitride devices result in very high operation speed and are remarkably stable within a broad temperature range, allowing device operation above 500 °C. The developed IC technology is based on three key elements: (1) exceptional quality III-nitride heterostructure with very high carrier concentration and mobility that enables IC fast operation in a broad temperature range; (2) heterostructure field effect transistor approach that provides fully planar IC structure which is easy to scale and to combine with the other high temperature electronic components; (3) robust design with self-compensating 2DEG load resistors, advance metallization and high-k passivation/gate dielectrics, specially developed for high temperature operation. The feasibility of technology was demonstrated by modeling, design and fabrication of inverter and differential amplifier type of ICs using III-nitride heterostructures. IC's performance was studied using probe station with heating chuck in ambient atmosphere. Temperature stability of structures with various barrier compositions was compared. At temperature exceeding 500 °C the developed ICs show the leakage currents below 10−7A, unit-gain bandwidth above 1 MHz and internal response time 45 ns.
Topside Nanocrystalline Diamond Integration on AlGaN/GaN HEMTs for High Temperature Operation
Authors: Koehler Andrew D. , Anderson Travis J. , Tadjer Marko J. , Feygelson Tatyana I. , Hite Jennifer K. , Hobart Karl D. , Pate Bradford B. , Kub Francis J. , Eddy Charles R.
Published: October 2015

GaN high electron mobility transistors (HEMTs) performance is limited by increased channel temperature, particularly resulting from self-heating during high power operation. Topside nanocrystalline diamond (NCD) layers have been integrated on AlGaN/GaN (HEMTs) to improve thermal management. HEMTs with NCD heat-spreading layers exhibit a 20% decrease in peak channel temperature compared to reference HEMTs, measured by Raman thermography, as well as improved sheet carrier density, transconductance, sheet resistance, Hall mobility, on-state resistance, and breakdown voltage. A “gate after diamond” approach is implemented to improve the thermal budget of the deposition process while maintaining the integrity of the Schottky gate electrode in a scalable process. Processing improvements for integrating NCD-capping with the HEMT are being pursued, such as eliminating the SiNx passivation interlayer, such that the NCD film is directly on the AlGaN barrier, as well as a sacrificial gate process. Also, boron doped p+-NCD films were implemented as gate electrodes for the AlGaN/GaN HEMT to place the heat-spreading layer in direct contact with the heat source, for a thermally stable heat-spreading gate contact.
High Temperature Tantalum-MnO2 Capacitors: >200° C
Authors: Jasso H. , Tempel K. , Bishop H.
Published: October 2015

For years, the Tantalum SMD MnO2 Capacitor, in its solid-state structure, was typically rated with a maximum temperature rating of 125°C. The introduction of advanced technology, some time ago, allowed increasing the maximum working temperature to 150°C, 175°C and 200 °C respectively. Now, with the introduction of more advanced materials, such as carbon and silver, and the implementation of state of the art processes such as Nickel platting, optimizing chemical impurity (F-Tech) and a non-destructive testing technique (SBDS), the temperature range capability of Tantalum SMD MnO2 Capacitor can be extended to more than 200°C. This paper will provide the current results obtained during the development process of new T501 series (>200°C), parametric and statistical data are shown for each tests performed. A discussion of the advantages related to the use of these new technologies is included. The path forward to get a final qualification for this product is also discussed. Potential application areas for this new Tantalum SMD MnO2 series are explored in the latter stages of this presentation.
Stacked Ceramic Capacitors for High Temperatures (≥200°C)
Authors: Bultitude John , Jones Lonnie , McConnell John , Gurav Abhijit
Published: October 2015

High temperature applications at 200°C or above in electronics for down-hole drilling are driving the development of capacitors with ever more reliable performance. Deeper wells with increased temperatures and pressures have resulted in exposure to harsher conditions for longer times for the electronics used in the extraction tools and deep-well control instrumentation. The capacitor solutions currently available for 200°C operation are reviewed by value and rated voltage. Some key reliability factors attributed of the various technologies are identified. The recent development of stacks made using multi-layer ceramic capacitors (MLCC) of Class-I C0G type dielectric material with nickel inner electrodes are outlined with respect to their performance benefits at ≥ 200°C. Due to its linear dielectric nature this material exhibits highly stable capacitance as a function of temperature and voltage. The development of higher voltages and larger case size capacitors using this technology is discussed together with their incorporation into stacked ceramic capacitors by soldering on lead frames. Stacks of multi-layer ceramic capacitors (MLCC) allow capacitance to be maximized within the volume available. However, the solder interconnects must be evaluated to assess the long term reliability of the stacks at higher temperatures particularly with respect to maintaining mechanical and electrical integrity. The development of a custom high temperature shear test to evaluate the performance of different solder interconnects at temperatures from 200 to 260°C is described. Evaluations of two different HMP Pb-based solders are presented. The high and low temperature shear test data acquired for these solders is analyzed in terms of the strain and strain energy when force is applied. Changes in performance after exposure to temperatures ≥ 200°C are assessed. The results are interpreted with respect to the values required to survive high g-forces and the performance of the different solder compositions. Performance considerations for high shear strength interconnects at 200°C and beyond are discussed.
Class-I and Class-II Ceramic Capacitors for High Temperature Applications
Authors: Gurav Abhijit , Xu Xilin , Magee Jim , Phillips Reggie , Ashburn Travis
Published: October 2015

There is a growing need for ceramic capacitors for applications at temperatures of 150°C or above, such as electronics for down-hole drilling and exploration, geothermal energy generation and power electronics. Conventional X7R and X8R type ceramic capacitors are designed for applications up to 125°C and 150°C, respectively. At temperatures above 150°C, these types of capacitors typically suffer from degradation of reliability performance and severe reduction in capacitance, especially under DC bias conditions. Recently, a Class-I C0G dielectric has been developed using nickel electrodes for high temperature application up to 200°C and beyond. Due to its linear dielectric nature, this material exhibits highly stable capacitance as a function of temperature and voltage. Multi-layer Ceramic Capacitors (MLCC) made from this material can be qualified as X9G with robust reliability. We have also developed a modified-X7R dielectric composition with nickel internal electrodes to design robust reliability in this Class-II dielectric at 175°C. This paper will report electrical properties and reliability test data on these Class-I C0G and Class-II ceramic capacitors at high temperatures of 150–200°C and above.
Development of a 300°C capable SiC based operational amplifier
Authors: Tilak Vinayak , Chen Cheng-Po , Losee Peter , Andarawis Emad , Stum Zachary
Published: October 2015

Silicon carbide based ICs have the potential to operate at temperatures exceeding that of conventional semiconductors such as silicon. Silicon carbide (SiC) based MOSFETs and ICs were fabricated and measured at room temperature and 300°C. A common source amplifier was fabricated and tested at room temperature and high temperature. The gain at room temperature and high temperature was 7.6 and 6.8 respectively. A SiC MOSFET based operational amplifier was also fabricated and tested at room temperature and 300°C. The small signal open loop gain at 1kHz was 60 dB at room temperature and 57 dB at 300°C. Long term stability testing at 300°C of the MOSFET and common source amplifiers showed very little drift.
Characterization of Circuit Blocks for Configurable Analog-Front-End
Authors: Ohme Bruce W. , Larson Mark R. , Tulpule Bhal , Behbahani Alireza
Published: October 2015

Analog functions have been implemented in a Silicon-on-Insulator (SOI) process optimized for high-temperature (>225°C) operation. These include a linear regulator/reference block that supports input voltages up to 50V and provides multiple independent voltage outputs. Additional blocks provide configurable sensor excitation levels of up to 10V DC and/or 20V AC-differential, with current limiting and monitoring. A dual-channel Programmable-Gain-Instrumentation Amplifier (PGIA) and a high-level AC input block with programmable gain and offset serve signal conditioning, gain, and scaling needs. A multiplexer and analog buffer provide an output that is scaled and centered for down-stream A-to-D conversion.

Limited component availability and high component counts deter development of sensing and control electronics for extreme temperature (>200°) applications. Systems require front-end power conditioning, sensor excitation and monitoring, response amplification, scaling, and multiplexing. Back-end Analog-to-Digital conversion and digital processing/control can be implemented using one or two integrated circuit chips, whereas the front-end functions require component counts in the dozens.

The low level of integration in the available portfolio of SOI devices results in high component count when constructing signal conditioning interfaces for aerospace sensors. These include quasi-DC sensors such as thermo-couples, strain-gauges, bridge transducers as well as AC-coupled sensors and position transducers, such as Linear Variable Differential Transducers (LVDT's). Furthermore, a majority of sensor applications are best served by excitation/response voltage ranges that typically exceed the voltage range of digital electronics (either 5V or 3.3V in currently available digital IC's for use above 200°C). These constraints led Embedded Systems LLC to design a generic device which was implemented by Honeywell as an analog ASIC (Application Specific Integrated Circuit).

This paper will describe the ASIC block-level capabilities in the context of the typical applications and present characterization data from wafer-level testing at the target temperature range (225C).

This material is based upon work performed by Honeywell International under a subcontract from Embedded Systems LLC, funding for which was provided by the U.S. Air Force Small Business Innovative Research program.
High Temperature 0.35 Micron Silicon-on-Insulator CMOS Technology
Authors: Kappert Holger , Dreiner Stefan , Dittrich Dirk , Grella Katharina , Kelberer Andreas , Klusmann Miriam , Kordas Norbert , Kosfeld Andre , Schmidt Alexander , Paschen Uwe , Kokozinski Rainer
Published: October 2015

Silicon-on-Insulator (SOI) is the most commonly used technology for integrated circuits capable of operating at high temperature. Due to the efficient reduction of leakage current paths much higher operation temperatures are achievable with SOI than with bulk technologies. Published work on high temperature CMOS circuits typically refers to technologies with a minimum feature size of 0.8 to 1.0 micron [1][2][3] even though for complex digital circuits this results in large die size. Technologies with smaller feature size are available but typically not suitable for reliable high temperature operation due to high leakage currents, decreasing threshold voltages over temperature or reliability issues with the standard aluminum metallization.

Fraunhofer IMS has developed a high temperature 0.35 micron thin film SOI technology. The mixed signal technology provides numerous devices, e.g. specific transistors for analog and digital circuit design, diodes, resistors and voltage independent capacitors. Also non-volatile memory cells (EEPROM) are available. In addition the technology is equipped with a tungsten metallization for highly reliable operation even at high temperatures. An overview on the new technology including characterization results of devices and test circuits is given in this paper.
A 200 °C Motor Control ASIC
Authors: Majerus Steve J. A. , Goff Daniel T. , Merrill Walter
Published: October 2015

A custom application-specific integrated circuit (ASIC) has been designed for positional control of brushless DC or servo motors in high-temperature (>200 °C) environments. Applications would include valve and position control for aerospace and industrial systems. Patented high-temperature circuit design techniques facilitate hightemperature operation from a conventional, low-cost, 0.5-micron bulk CMOS foundry process. The ASIC is highly integrated to enable software- and processor-free local control of motor position, and uses external power MOSFETs for motor commutation. Motor position can be controlled in open- or closed-loop modes with an integrated rotational variable displacement transformer (RVDT) direct digital synthesis (DDS) waveform generator, rail-to-rail op-amp driver and demodulation circuit. The ASIC can accept both analog (0–10 V) or digital (SPI bus) position setpoint commands from an external controller. Motor position is indicated by both analog and digital output signals. The full-scale displacement of the controlled motor is programmable from 5 to 8 bits of resolution, permitting 32–256 positions of control. Safety features such as a 500-ms power-on delay, overtemperature and motor overcurrent detection, and control signal undervoltage lockout were included to minimize the need for external control.

ASIC bench-test results confirmed circuit functionality at ambient temperatures up to 225 °C using room-temperature power MOSFETs and motor load. ASIC performance at the 8-bit level was demonstrated, although the clock oscillator frequency shifted by about 15% over the full temperature range. Control of the motor at 200 °C was also demonstrated, although moderate loss of motor holding torque was observed due to internal heat generation in the motor. The ASIC was combined with commercially-available off-the-shelf high-temperature components on a printed wiring board (PWB) to form a compact (4 × 3.5 inch) motor control demonstration system capable of prolonged operation at temperatures beyond 200 °C. Environmental and long-term testing of the PWB is planned to demonstrate system reliability.
Highly Integrated and Isolated Universal Half-Bridge Power Gate Driver and Associated Flyback Power Supply for High Temperature and High Reliability Applications
Authors: Gras David , Pautrel Christophe , Fanaei Amir , Thepaut Gregory , Chabert Maxime , Laplace Fabien , Picun Gonzalo
Published: October 2015

In this paper we present a highly integrated, high-temperature isolated, half-bridge power gate driver demo board, based on turnkey X-REL chipset: XTR26010 (High-Temperature Intelligent Gate Driver), XTR40010 (High-Temperature Isolated Two Channel Transceiver), XTR30010 (High-Temperature PWM Controller), and XTR2N0825 (High-Temperature 80V N-Channel Power MOSFET).

The XTR26010 is the key circuit in this chipset for power gate drive application. The XTR26010 circuit has been designed with a high focus in offering a robust, reliable and efficient solution for driving a large variety of high-temperature, high-voltage, and high-efficiency power transistors (SiC, GaN, Si) existing in the market. Furthermore, the XTR26010 circuit implements an unprecedented functionality for high-temperature drivers allowing safe operation at system level by preventing any cross-conduction between high-side and low-side switches, through isolated communication between high-side and low-side drivers.

The XTR40010 is used for isolated data communication between a microcontroller or a PWM controller with the power driver (XTR26010).

For supplying the half-bridge gate driver, a compact isolated flyback power supply has been developed thanks to the versatile voltage mode PWM controller XTR30010 and the XT2N0825 N-Channel MOSFET. The full system has been successfully tested while driving different brands of SiC MOSFETs up to Ta=200°C, 600kHz of switching frequency and 600V high-voltage bus (limited by isolation transformers used). The demo board presented can be easily modified to drive other SiC and GaN transistors available in the market. The 200°C limitation of the demo board is due to passives, PCB material, and the solder paste used. However, all X-REL active circuits have been qualified within specifications well above 230°C.
High Temperature Isolated Switch Mode Power Supply with Integrated Power and Feedback Transformer
Authors: Snyder Harold L.
Published: October 2015

High temperature switch mode power supplies (SMPS) typically utilize magnetic solutions such as low permeability transformers for isolation from ground loops. However, imposed design constraints almost always restrict the size of switch mode power supply systems to less than the minimum space necessary for a good design, resulting in only adequate and sometimes unreliable switch mode power supply designs. Integrating the control loop and magnetic system functions is implemented by taking advantage of the bi-directional characteristics of transformers, which allows the designer an opportunity to further minimize the design space by eliminating unnecessary loop components. This is a prudent step prior to the construction of high temperature hybrids and multichip modules. Combining the operation of both the control loop and the magnetic transformer allows the designer to reduce the size of the design, regain the ability to provide a good design in the volume allotted, while still maintaining loop stability. The design procedure for this integrated control loop and magnetics system is examined, and an example circuit is simulated in SPICE with a Jiles-Atherton hysteresis model, and the circuit is realized through construction and measurements which are presented for a single forward based design targeted for operation at high temperatures.
8-15 KV HIGH TEMPERATURE SIC PIN AND SCHOTTKY RECTIFIERS
Authors: Singh Ranbir , Sundaresan Siddarth
Published: October 2015

his paper reports on ultra-high voltage, >15 kV SiC PiN rectifiers exhibiting >95% of the avalanche rating and 115 V/μm. This is one of a few reports on > 15 kV blocking voltages measured on any single semiconductor device, and the highest percentage of the avalanche limit ever reported on devices fabricated on > 100 μm thick SiC epilayers. Excellent stability of on-state voltage drop (VF) is displayed by 5.76 mm2 and large-area, 41 mm2 PiN rectifiers, when continually biased at high current densities for several days. The impact of carrier lifetime on the device performance for SiC bipolar devices with ultra-thick (≥100 μm) base layers is investigated by comparing I-V-T characteristics of SiC PiN rectifiers fabricated on 100 μm and 130 μm thick epilayers.
Dielectric Performance of a High Purity HTCC Alumina at High Temperatures - A Comparison Study with other Polycrystalline Alumina
Authors: Chen Liang-Yu
Published: October 2015

A very high purity (99.99+%) high temperature co-fired ceramic (HTCC) alumina has recently become commercially available. The raw material of this HTCC alumina is very different from conventional HTCC alumina, and more importantly there is no glass additive in this alumina material for co-firing processing. Previously, selected HTCC and LTCC (low temperature co-fired ceramic) alumina materials were evaluated at high temperatures as dielectric and compared to a regularly sintered 96% polycrystalline alumina (96% Al2O3), where 96% alumina was used as the benchmark. A prototype packaging system based on regular 96% alumina with Au thick-film metallization successfully facilitated long term testing of high temperature silicon carbide (SiC) electronic devices for over 10,000 hours at 500°C. In order to evaluate this new high purity HTCC alumina for possible high temperature packaging applications, the dielectric properties of this HTCC alumina substrate were measured and compared with those of 96% alumina and a previously tested LTCC alumina from room temperature to 550°C at frequencies of 120 Hz, 1 KHz, 10 KHz, 100 KHz, and 1 MHz. A parallel-plate capacitive device with dielectric of the HTCC alumina and precious metal electrodes were used for measurements of the dielectric constant and dielectric loss of the co-fired alumina material in the temperature and frequency ranges. The capacitance and AC parallel conductance of the capacitive device were directly measured by an AC impedance meter, and the dielectric constant and parallel AC conductivity of the dielectric were calculated from the capacitance and conductance measurement results. The temperature and frequency dependent dielectric constant, AC conductivity, and dissipation factor of the HTCC alumina substrate are presented and compared to those of 96% alumina and a selected LTCC alumina. Other technical advantages of this new co-fired material for possible high packaging applications are also discussed.
Silicon Capacitors with extremely high stability and reliability ideal for high temperature applications
Authors: Bunel Catherine , Lengignon Laurent
Published: October 2015

With the wide range of existing capacitors, the end user's requirements are roughly met but most of the capacitors see their performances largely impacted when they are submitted to high temperature. In this paper we present the Silicon Capacitors highly recommended for applications in the geothermal, oil well logging, automotive and military. They can operate in a wide operating temperature range and they withstand temperature up to 250°C, with extremely high insulation resistance and very good stability. These capacitors, already extensively used for years in miniaturized equipment and computers, feature high miniaturization with a large capacitance to volume ratio, thanks to the IPDiA 3D Silicon technology, extremely stable and reliable even at 100μm thickness. Available in hundreds or thousands of nanofarads, in various sizes and custom configurations, these capacitors are usable at low frequencies but they are also appropriate for RF applications. The recent progress in the 3D Silicon Capacitor IPDIA technology, which moves the world wide record from 250nF/mm2 up to 550nF/mm2, will give even more room to higher integration. This is an ultra key driver to growth for High reliability applications.
The Thermal Integrity of Integrated GaN Power Modules
Authors: Roberts J. , MacElwee T. , Yushyna L.
Published: October 2015

In this paper the authors describe GaN (gallium nitride) power switching transistors that use copper post and substrate via interconnect techniques. These transistors can be matrixed to allow a parallel array of the devices to provide very low on-resistance and high operating voltages. At 150 °C the basic building block which is a 2 × 2 mm die, provides 1200 V / 14 A. A 2×2 matrix array of these transistors provides for example, 1200 V / 56 A operation. The overall GaN device size is 4 × 4 mm. This high current density is achieved by using a unique castellated island topology. This provides short fingers that are not required to carry high current. No high current tracks are provided on-chip because on-chip metal is typically less than 3 microns thick. The die has 12 copper posts on the source islands that carry the current to the CMOS driver device. The CMOS driver is used in a cascode configuration which allows the normally-on GaN transistor to be operated with convenient normally-off functionality. The two devices are combined in a modular assembly. The paper provides a thermal analysis of the assembly. The objective of the design is to keep the ‘junction’ temperature of the GaN transistor below 150 °C.
High temperature, Smart Power Module for aircraft actuators
Authors: Falahi Khalil El , Hascoët Stanislas , Buttay Cyril , Bevilacqua Pascal , Phung Luong-Viet , Tournier Dominique , Allard Bruno , Planson Dominique
Published: October 2015

More electric aircraft require converters that can operate over a wide temperature range (−55 to more than 200°C). Silicon carbide JFETs can satisfy these requirements, but there is a need for suitable peripheral components (gate drivers, passives. . . ). In this paper, we present a “smart power module” based on SiC JFETs and dedicated integrated gate driver circuits. The design is detailed, and some electrical results are given, showing proper operation of the module up to 200°C.
Robust True LDO Linear Voltage Regulator and Digitally Trimmable Buffered Precision Voltage Reference for High-Temperature, Low-Voltage Applications
Authors: Dusé Yoann , Laplace Fabien , Joubert Nicolas , Montmayeur Xavier , Zitouni Noureddine , Vieusses Sebastien , Thepaut Gregory , Anota Arnaud , Picun Gonzalo
Published: October 2015

We present in this paper two new products for high-temperature, low-voltage (2.8V to 5.5V) power management applications. The first product is an original implementation of a monolithic low dropout regulator (XTR70010), able to deliver up to 1A at 230°C with less than 1V of dropout. This new voltage regulator can source an output current level up to 1.5A. The regulated output voltage can be selected among 32 preset values from 0.5V to 3.6V in steps of 100mV, or it can be obtained with a pair of external resistors. The circuit integrates complex analog and digital control blocks providing state of the art features such as UVLO protection, chip enable control, soft start-up and soft shut-down, hiccup short-circuit protection, customer selectable thermal shut-down, input power supply protection, output overshoot remover and stability over an extremely wide range of load capacitances. The circuit offers a fair ±2% absolute accuracy and is guaranteed latch-up free.

The second product is an advanced high-temperature, low-power, digitally trimmable voltage reference (XTR75020). Thanks to a custom, 1-wire serial interface, the absolute precision and the temperature coefficient can be adjusted in order to obtain an accuracy better than 0.5% with a temperature coefficient bellow ±20ppm/°C. On-chip OTP memory for trimming of absolute value and temperature coefficient makes the circuit extremely accurate and almost insensitive to drifts over time and temperature. The circuit features a class AB output buffer able to source or sink up to 5mA and remains stable with any load capacitance up to 50μF. The XTR75020 has nine preset possible output voltages. The source and sink short circuit current always remains bellow 25mA. The quiescent current consumption is 300μA typical at 230°C while the standby current is, in all cases, under 20μA.

Both devices are designed on a latch-up free silicon-on-insulator process.
Latchup Immunity in High Temperature Bulk CMOS Devices
Authors: Lowther R. , Morris W. , Gifford D. , Duff D. , Fuller R.
Published: October 2015

High density, low power 180nm and 130nm CMOS SRAMs have been manufactured on bulk silicon wafers using a modified CMOS commercial process that hardens the junction isolation and has demonstrated latchup immunity at temperatures >200°C. TCAD simulations confirmed by high temperature testing indicate that a latch up free performance of SRAMs manufactured on bulk silicon modified by the HardSIL™ technology will easily extrapolate to 250°C. These process modifications result in significantly more robust CMOS circuits making them more suitable for highly reliable operations in extreme environments – such as radiation and high temperature. The unique capability of HardSIL™ technology to enhance existing IC products has demonstrated excellent results with several commercial circuits. This new approach enables the conversion of commercial off the shelf (COTS) circuits to hardened hi-rel commercial circuits with dramatically improved survivability to either radiation or high temperatures. Latchup immunity has been demonstrated on two high-density bulk silicon CMOS SRAMs: a 16Mbit asynchronous SRAM manufactured at the 180nm design node and an 8Mbit dual port synchronous SRAM manufactured at 130nm. Both parts were produced in a high-volume, low-defect commercial CMOS fabrication facility in the USA. The SRAM parts were packaged in ceramic packages and characterized at temperatures ranging from 25°C to 225°C. Characterization data indicates both excellent static leakage and dynamic circuit performance for both SRAMs at these elevated temperatures. Device test structures designed with typical layout spacing rules were evaluated to quantify latchup and isolate the various leakage mechanisms. Detailed results for these test structures are presented and compared to the SRAMs using the modified HardSIL™ process.
Reliability Assessment of Passives for 300°C and 350°C
Authors: Shaddock David , Vert Alexey , Zhang Tan , Zhang Rui , Johnson R. Wayne
Published: October 2015

Highly accelerated life testing (HALT) is used to quickly assess the reliability of passive components for geothermal applications operating at 300°C ambient temperatures. The HALT methodology uses combined stresses to accelerate the failure of capacitors and resistors. This paper describes the test methodology and results on capacitors and resistors at 300°C and 350°C. Life models for the components are presented.
Enhanced High Temperature Power Controller
Authors: Henfling Joseph A. , Atcitty Stan , Maldonado Frank
Published: October 2015

This paper describes an implementation strategy used to develop a high temperature power controller. The system is based on using high-temperature (HT) silicon-on-insulator (SOI) technology with silicon carbide (SiC) based integrated circuits (ICs) to create an efficient, high-temperature power controller. Two drives were tested with this system, one using normally off JFET switching and the other using MOSFET switching. Normally off JFETs made from SiC were used to drive the output loads. Such circuit designs will improve the efficiency of future smart grid power controllers.
ESEM as a Tool for Studying High Temperature Electronics
Authors: Svensson Stefan , Ericson Fredric , Hjort Klas , Klintberg Lena
Published: October 2015

Researchers studying materials and processes at high temperatures are often restricted to do evaluation afterwards and at room temperature using e.g. scanning electron microscopy (SEM). Limited by high vacuum, outgassing and non-conducting samples are difficult to study with SEM. For such samples, environmental scanning electron microscope (ESEM) is an alternative that is particularly suited also for high temperature in-situ studies. The electron detector in the ESEM make use of otherwise unwanted scattering of electrons as an amplifier of the signal, and by using differential pumping, it is possible to introduce several mbar of either oxygen, water vapor, or a gas of choice into the sample chamber while still maintaining the high-vacuum in the electron column. The auxiliary gas neutralizes surface charges built up by the electron beam, which makes it possible to image non-conductive and outgassing samples, thus making it possible to study e.g. polymeric and high temperature materials. Our ESEM, FEI XL30, have a heating stage making it possible to reach temperatures up to 1500°C. Equipped with electrical feed-throughs, the instrument can be used to study high temperature phenomena on electrically activated components.

ESEM is an instrument that has found its use for biological and organic samples. However, less work has been done using it for high temperature processes. Here, we show real-time imaging of the sintering of dielectric and Ag thick-film prints on AlN substrates. The use of the electrical feed-throughs to activate electrical components and study them at high temperatures is also demonstrated. ESEM is a versatile tool for high temperature studies and in-situ analysis of electrical components, solder processes and different die-attach materials.
250°C Operating Temperature Dielectric Film Capacitors
Authors: Donhowe Mark , Lawler Jeff , Souffie Sean , Stein E. Lee
Published: October 2015

High operating temperature electronic components are needed for a variety of military, aerospace, down-hole, and electric vehicle applications. One of the limiting technologies is the availability of highly reliable capacitors that operate at temperatures greater than 150°C and up through 250°C.

This paper introduces a high breakdown strength dielectric film Gore has developed for metallized film capacitors. In addition to exceptionally high breakdown voltages, the 6 μm PTFE film exhibits low dissipation factor and stable capacitance over a wide temperature range. Film properties were tested from −50°C to 250°C and both wound film/foil and metallized film capacitors were fabricated and tested from RT to 300°C.
Reliability Testing on a Multilayer Chip Inductor Fabricated From a Ferrite With a 350 °C Curie Point
Authors: Galipeau James , Slama George
Published: October 2015

As more electronics are used in down-hole energy exploration, under the hood automotive applications, and in other environments where temperatures exceed 200 °C; there is a need for compact passive magnetic components that operate reliably at elevated temperatures. Most ferrites used to make multi layer ceramic inductors have Curie temperatures in the 100–200 °C range. As temperatures rise above the Curie point ferrites lose their magnetic properties and become paramagnetic. This means that traditional multi-layer ceramic inductors suffer severe performance degradation when operated at elevated temperatures. Therefore, ferrite materials with higher Curie temperatures need to be developed to increase device performance and reliability at these high temperatures. In this work inductors were made from a low-temperature, co-fire compatible, ferrite with a Curie temperature of 350 °C. The inductors were first subjected to a 1000 hour life test at 300 °C during which the electrical parameters were found to change no more than 4 %. The inductance, resistance, core loss, and saturation flux density of the inductors were measured at various temperatures. Additional testing focused on the effect of temperature on the device's frequency profile and performance changes under thermal cycling and thermal shock.