Silber, Dieter
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Silber, Dieter
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Silber, Dieter
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Silber, D.-H.
Silber, D.
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Item type:Publication, Turning-On behavior of high voltage optically and electrically triggered thyristors(2010-02-02); ; 1a.Usage of LTTs in high voltage switching applications like HVDC and SVC simplifies/avoids the control circuitry and thereby offers robust power systems with lower production cost. 1b. Integration of protection against all possible fault triggering mechanisms (including reapplied dv/dt) is possible. Therefore, LTTs offer a genuine alternative to ETTs in very high voltage switching applications.2a.Dynamic punch-through reduces turn-on delay in symmetrical thyristors. Kirk effect displaces the hot spot during triggering from cathode side to anode side in asymmetrical thyristors2b. Tandem 13kV thyristor offers an increase of 5kV in blocking voltage with only doubling the on-state losses, without any significant difference in switching losses compared to an 8kV thyristor.2c. Anode shunting is the better alternative solution for the problem of blocking at high temperatures in Tandem 13kV thyristors. A weak anode shunting density, which causes only a negligible increase in the on-state losses, is sufficient to ensure blocking at high temperatures. 3a. An integrated lateral resistance is necessary to protect the inner AGs and thereby to increase the di/dt capability of a thyristor. However, heat distribution across the integrated lateral resistance shall be homogeneous.3b. Homogeneous heat distribution is achieved by a non-linear resistance structure which also provides an enhanced protection to the inner AGs without increasing the minimum triggering voltage and therefore results in a higher di/dt capability.3c. Negative resistance (Snap-back) phase of the non-linear resistor is forbidden. A method to eliminate snap-back is investigated.4a. Several novel gate structures with the aim of increasing the di/dt capability of thyristors are investigated.-Reducing the p emitter efficiency or completely eliminating the p emitter in the AG1 region.-Reduced Current Gain (RCG) AG-Self Turn Off (STO) AG-Capacitive ballastingThese novel gate structures are submitted at the German patent office for patent rights.4b. A concept of using an LTT as a pilot thyristor with a segmented n emitter to trigger a main ETT is investigated with the aim of achieving protection against fault reapplied dv/dt triggering.doctoral thesis461 136 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Untersuchung und Entwicklung von Stromsensorkonzepten für Leistungsbauelemente mit lateralem und vertikalem Stromfluß.(2001-01-23); ; ; A new monolithic integrated high side current sense principle is developed and investigated for power semiconductor devices with lateral and vertical current flow. In such devices the well-known low side sense principles are unsuitable. The special requirements for the integration and the signal processing are discussed in detail. As an example, the new concept is presented with a lateral-vertical transistor (LV-transistor). The load current enters the device on the top of the chip and it is divided to flow to a vertical and lateral main contact. The current distribution in the device depends on the device layout and the operating point. The usual integrated low side current sense principle consists of a current mirror and a sense resistor in the current path. Therefore, only the lateral current component in the LV-transistor could be detected. Especially in the case of turning off the device and simultaneous current control the sense signal will be ambiguous. In the new concept the sense resistor is directly connected to the high voltage side in the load current path, so that the relation between the sense signal and the load current is almost independent of the device parameters. The new current sense concept allows the detection of the current level and makes the current control in a lateral-vertical power switch possible. This is investigated and demonstrated by a test structure of an LV-transistor under ohmic load and an external control system. The temperature and voltage dependence of the sense signal is simulated and measured to define the demands for the subsequent circuitry. For a simple MOS-transistor the results are compared with the behaviour of the low side current sense principle in the case of detecting a current flag. However, it is a disadvantage of the concept, that the sense signal must be transferred from the high voltage side to the low voltage side for further processing. The possibility of signal transfer by monolithic integrated high resistive polysilicon resistors on the RESURF-region is investigated by numeric simulation and measurement. The reactions of the integrated components on the breakdown behaviour of an LV-transistor are simulated and classified as uncritical in respect of the application. The disturbing effects on the sense signal are caused mainly by capacitive coupling between the power device and the high ohmic transfer resistors and determine the critical frequency of the system. Finally, some parasitic influences for the case of current control are analysed and the demands for the processing circuit are discussed. As a result, the fundamental problems of the high side sense principle are investigated for a special LV-device and appropriate solutions are proposed.doctoral thesis259 113 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Design, Simulation and Analysis of Novel Types of Unipolar Diodes(2013-06-03); ; ; With the growing demand of low and medium voltage switch-mode power supplies (SMPS) for use in the state-of-the-art integrated circuits, the development of output rectifiers with low forward voltage drop and low reverse leakage current becomes essential. In low voltage SMPS applications (1 to 5 V), the on-state loss of the fast recovery p-i-n diode or the Schottky diode contributes greatly to the total power loss in power supplies. This is due to their forward threshold voltage. One possible way to achieve low on-state losses is to reduce or remove the forward threshold voltage. The first part of this thesis is mainly devoted to a novel Regenerative diode structure based on Silicon material. Its main advantages are reduction or removal of forward threshold voltage and much improved reverse characteristics without the necessity of a gate control like in synchronous rectifiers. The silicon unipolar device application is, however, restricted to relatively low voltages because of on-state and blocking problems at device blocking capabilities above 200 V. For high voltage applications (> 200 V), SiC Schottky or JBS rectifiers have demonstrated a good differential on state resistance and reasonable blocking behavior. In principle, one could try to construct a Regenerative diode like device based on SiC material, but poor hole mobility and much less developed integrated device technology seem to discourage such efforts. However, the second part of this thesis work presents a simulation study on a Si/6H-SiC heterojunction. The p-Si/N-6H-SiC heterojunction diode behaves like a Schottky diode but with much lower threshold voltage than that of the 6H-SiC SBD. Therefore, the heterojunction diode has better on state characteristics than 6H-SiC SBD without sacrificing in blocking.doctoral thesis301 181 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Charakterisierung und Einfluss parasitärer elektromagnetischer Effekte in leistungselektronischen Systemen(2007-04-11); ; ; Structure-caused parasitic electromagnetic effects have a great importance in power electronic modules and systems, since they affect both their function mode and the security of the system. This work deals with the extraction of parasitic elements from the circuit layout based on field theory, clarifies its different influences on the switching process of power semiconductors and points constructional proposals for solution out for the avoidance or reduction of parasitic effects.Using a PEEC ("Partial element Equivalent Circuit") approach it is shown, how partial elements with consideration of skin- and proximity-effect can be determined by suitable computer simulations from the power electronic circuit layout. For typical module dimensions partial self and mutual inductances of the conductors, bond wires and busbars are indicated, whereby also the influence of the substrate thickness and the dependence on the frequency are examined.It is shown by simulations that layout-dependent inductive positive and negative feedbacks between power and control circuit can affect the switching behaviour of power transistors considerably. It is illustrated, as this inductive coupling can be used consciously, in order to adjust switching speeds and to realize a symmetrical switching behaviour in the parallel connection of power devices.On the basis of a half bridge module on DCB substrate it is shown by simulation and measurement that eddy currents in the backside metallization of the substrate have a great influence on the symmetrical load of IGBTs in a parallel connection.During the turn-off phase of bipolar power devices paralleled in power modules very disturbing high frequency oscillations in the range between 70 MHz and 700 MHz have sometimes been observed. The excitation mechanism of these spontaneously appearing oscillations in the tail current phase can be explained by a transit-time diode effect which works in analogy to a BARITT-type diode. The new PETT-effect ("Plasma Extraction Transit Time") is based on a periodic extraction of holes from the electron-hole plasma in combination with a suitable transit-time of the charge carriers passing the space-charge region. The LC resonant circuit is formed by the junction capacitances of the power devices itself and the parasitic inductances between the chips arranged in parallel. The experiences from measurements are confirmed by suitable device simulations. The observed oscillations react very sensitively to changes in the operating parameters (temperature, DC link voltage and tail current level) and the natural frequency of the resonant circuit.In order to absorb PETT oscillations in the power module considerably or prevent their emergence, three new constructional measures based on the integration of resistive elements are presented. The effectiveness of these measures is confirmed by electromagnetic field simulations.During dynamic current measurements with magneto-resistive sensors in power modules measuring errors were observed because of parasitic proximity effects. It is shown by electromagnetic field simulation that the measuring errors can be substantially suppressed by adding a ferrite core or an eddy current plate brought in the position suitably.doctoral thesis490 340 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Leistungsbauelemente in der Automobilindustrie: Erhöhung der Robustheit von Schutz- und Nutzstrukturen bei verringerten Flächen(2010-11-29); ; ; The target of this thesis is to provide an insight of the internal sequences of semiconductor devices under extreme electrical and thermal load. In addition, the limits of typical high voltage devices of a BCDMOS technology are shown. New options to increase the robustness within device development are explained using examples and afterwards generalized. Specific protection structures need to be used additionally if these options are not sufficient to achieve the required robustness. The related problems and limits are demonstrated using examples. First, an introduction to Smart Power and its process details, an overview about field effect transistors, bipolar structures in general and especially thyristors are given. Following ESD and ISO events, dualization and characteristics of H-bridges are analysed. The basic behaviour of power transistors is discussed. The so called Dual Thyristor is developed based on the theoretical background and its applications are shown. The Dual Thyristor combines significantly increased self protective characteristics with an excellent performance as a power switch. In this work an integrated version for a BCDMOS technology for Infineon Technologies AG is introduced. The Dual Thyristor as High-Side-Switch for an Half Bridge or H-Bridge has better cost/performance-indicators compared to p-channel and n-channel switches including driver stages. Lateral High-Voltage-Devices are discussed. Complex simulations are necessary to demonstrate the destruction processes. 2D simulation gives a first insight to internal processes. Parallelization of 2D-structures at the same or different sizes allows further qualitative improved statements about trigger behaviour of the parasitic bipolar transistor. However, the 3D thermodynamic simulation with extended simulation time of several weeks is needed to get quantitative valid statements regarding the device behaviour. Construction rules for a robust design are derived. For example, smooth doping profile from drift region to drain contact. Appropriate doping profile of the body towards the drift region enables dynamic base push out. A new construction of the drift region allows accumulation of carriers for the on state and further improved extraction of carriers in the off state combined with reduced length of drift region. All this measures can be realized at the same cost or with improved cost/performance ratio. Protection structures are used if a device is not able to fulfil the strong robustness requirements especially in the field of automotive applications. The internal workflows under extreme overload conditions, as trigger behaviour of bipolar and thyristor structures and the hence resulting problems are demonstrated using examples. Simulations demonstrate moving and jumping filaments. This can only be shown within 3D electrothermal simulations causing huge simulation effort. Thereof, a new possibility to adjust holding voltage for highly efficient bipolar structures is developed. The dynamically changing emitter efficiency when moving towards high injection is used. Finally, recommendations for circuit development, the state of technology as well as future trends are defined. The results of this thesis enable to increase the robustness of lateral high voltage and power devices. Thus, Infineon Technologies AG could reduce the device area up to a factor of three using the new technology. At the same time the specifications of the old technology are fulfilled. In the past, similar robustness could only be achieved by using vertical structures with significantly worse DC characteristics (e.g., RON, ISAT , VBD). The area increases by a factor of 1.7 to 2.4 using the vertical structures. In this thesis was demonstrated that new area optimized applications at reduced costs and the fulfilment of the same requirements are possible.doctoral thesis287 290 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Neue Sicherungselemente und Leistungsschalter auf der Basis des Dualen Thyristors(2007-04-20); ; ; The Phd thesis presents a simulation study on power device structures based on a dualization of the thyristor equivalent circuit. This dualization results in new power devices, namely, "Circuit Breaker" and "Safe Controlled Power Switch". Both the circuit breaker and the safe controlled power switch can be used to protect against over currents. The circuit breaker exhibits self protection against over currents while the safe controlled power switch with inherent over current turn-off capability is controlled by the MOS gates of the device. These novel power devices have very good on-state characteristics that are comparable to the on-state characteristics of the injection enhancement IGBTs.doctoral thesis335 147 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Simulationsuntersuchungen zur Grenzbelastbarkeit von IGBTs im Abschaltvorgang(2010-12-17); ; ; Within the frame of this thesis turn-off behaviour of IGBTs was investigated, focussed on Trench IGBT design. Temperature was introduced as additional mean for the device's behaviour. The existence of filament oscillations is proved. Neighbouring relations influence the sequence of the current-concentration carrying transistors. The filament self-extinguishing through plasma extraction is shown as driving force for the filaments' transition from one IGBT to another. Gate backlash was recognized as a reason for oscillation. The parasitic capacity of trench IGBTs was devoted attention. The oscillation itself as destructive mechanism was ruled out. It became clear, that temperature and thermal runaway make up the final destruction mechanism. Thermal feedback is the prerequisite for a stable local latch-up. Considerations were taken to provide conditions for informative, yet fast to be computed simulation setups. Variants of the trench cell were examined regarding their turn-off capabilities.doctoral thesis318 254 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Neue Emitterkonzepte für Hochspannungsschalter und deren Anwendung in der Leistungselektronik(2003-08-27); ; ; Nowadays conventional power pin-diodes have reached a mature development level in which no essential improvements can be expected. To drastically improve on state and switching properties, new design concepts are needed. Some solutions can be found in the literature. However, they show severe disadvantages from the chip fabrication and applicationpoint of view. New design concepts for silicon diodes with a blocking voltage larger than 2-3kV arepresented in this work. Using an additional gate signal terminal, the emitter efficiency of the p-emitter can be controlled, resulting in a state dependent suitable on-state and turn off bahaviour. The diode is therefore called Emitter Controlled Diode = ECD. Additional advantages are the blocking capability under all operating conditions compared to otherdesign concepts, good turn off characteristics even under critical switching conditions and apositive temperature coefficient. Investigations under severe turn off conditions have shown, that the turn on of a parasitic bipolar transistor is not critical. Comparing the emitter controlled diode with a conventional pin-diode with same power losses the current density can be increased by 30% and the silicon area can be reduced as well. Emitter controlled diodes can be fabricated with the standard power MOSFET production process. No additional masks or local lifetime control is needed.The basic concepts developed in this thesis are used to design an emitter controlled diode.The technological realisation has already been started.doctoral thesis292 334 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Physical Modelling of Advanced SiGeTransistors(2009-10-13); ; ; Many demanding high speed applications like optical communication operating at 40-100 Gb/s and 77 GHz automotive radar require transistors with a cutoff frequency fT of 200 GHz or above. Additionally, these applications also need transistors with high breakdown voltages, which are used e.g. for ESD protection and driver stages. Furthermore, 77 GHz automotive radar applications require varactors with sufficiently high tuning range to be integrated on the same chip. Such an integration of high voltage transistors and varactors with high tuning range into high frequency SiGe bipolar technologies is challenging due to the requirement of a shallow collector for the high speed transistor. In this work, a novel concept with two epitaxial layers is proposed for the simultaneous integration of high speed transistors, high voltage transistors, and varactors with high tuning range on the same chip. Using this concept, high speed transistors with 209 GHz cut-off frequency have been combined with high voltage transistors providing an emitter-collector breakdown voltage of 5 V. Additionally, the same concept allowed the development and optimization of a varactor for a voltage controlled oscillator (VCO)with high tuning range of 13 GHz and sufficiently low phase noise suitable for 77 GHz automotive radar applications. Process and device simulations leading to the optimum device combination, and design considerations related to the process flow, are presented. This work also describes extensive investigations of the emitter, collector, and base for improving the speed of future high speed transistors. As a part of emitter optimization, it has been found that by using a relatively simple un-doped silicon cap instead of the conventional p-doped silicon cap the cutoff frequency fT increases by 15 GHz (10%). This is verified by simulation and experiment. Using the double epi concept, the collector thickness of the high speed transistor can be reduced independent from the requirements of the high voltage transistor. A detailed simulation study concerning the collector thickness and doping for achieving high speed is presented as a part of collector optimization. Investigations show that by using a thin collector of 40 nm and a high collector doping of 1.5 angstroem 10^18 cm-3 in the standard high speed transistor an improvement in cutoff frequency of 45 GHz can be achieved. As a result of base optimization, it has been found that the combination of lateral emitter scaling down to 80 nm, a thin emitter-base spacer of 30 nm, high doping of 2 angstroem 10^20 cm-3 in the extrinsic base link region, and extending the base contact towards the emitter increases the maximum oscillation frequency fmax of the high speed transistor up to 700 GHz, which means a doubling of the present performance.doctoral thesis277 136 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Experimentelle Untersuchungen zu Minoritätsträger-Diffusionskonstanten in Silizium(2004-04-16); ; ; In the present study the transportation parameter diffusion coefficient of minority carriers in silicon is determined experimentally. Measurements take place over a entire range of temperature and over a entire range of doping concentration of holes in n-silicon and of electrons in p-silicon. The results are compared with the usually used data. The mobility model according to D.B.M. Klaassen, used in many device simulators, is used as reference. The mobility values are converted into diffusion coefficients with the help of the einstein relationship. Special attention is given to the experimental method. Special value is put to determine the diffusion coefficient in a maximally direct way. The focus of the present study is the practical development and application of the experiment. The mobility model according to Klaassen is confirmed for high temperatures for all measured doping concentrations. With doping concentrations below the Mott-transition deviations exist between measurement results and converted mobilities according to Klaassen. The deviations increase with decreasing of temperature on the one hand, and with increasing of doping concentration on the other hand and can be explained with excitons. Therefor a weighted average diffusion coefficient is formed wich lies between the diffusion coefficient according to Klaassen and the diffusion coefficient of the excitons. The weighting factor is the relative exciton concentration. The comparison between this weighted averaged diffusion coefficient with the measurement results supplies a very good agreement over the entire range of temperature. With doping concentrations above the Mott-transition no excitons can form. Here, the measurement results are compared with converted mobilities according to Klaassen. The comparison between these two diffusion coefficients also results in a very good agreement over the entire range of temperature.doctoral thesis261 108