Frank Hille

600 V Reverse Conducting (RC-)IGBT for Drives Applications in Ultra-Thin Wafer Technology

Reverse conducting IGBTs are fabricated in a large productive volume for soft switching applications, such as inductive heaters, microwave ovens or lamp ballast, since several years. To satisfy the requirements of hard switching applications, such as inverters in refrigerators, air conditioners or general purpose drives, the reverse recovery behavior of the integrated diode has to be optimized. Two promising concepts for such an optimization are based on a reduction of the charge- carrier lifetime or the anti-latch p+ implantation dose. It is shown that a combination of both concepts will lead to a device with a good reverse recovery behavior, low forward and reverse voltage drop and excellent over current turn- off capability of a trench field-stop IGBT.

Investigations on the ruggedness limit of 6.5 kV IGBT

The save operating area (SOA) of high voltage 6.5 kV IGBTs has been investigated. The ruggedness of the IGBT with planar cell structure is limited by the hole current density in the cell structure arriving from the avalanche generation under turn-off conditions. The impact of current density, V/sub cc/ and vertical IGBT structure on the ruggedness has been taken into account. With a modified cell design the avalanche generation can be reduced significantly. Simulations with a trench IGBT promises additional SOA improvement.

Numerical analysis of cosmic radiation-induced failures in power diodes

Silicon power diodes can run into thermal destruction due to cosmic radiation-induced effects. We performed electro-thermal coupled device simulations in order to explain the failure mechanism. The results are compared to ion irradiation experiments. We find a strong heating located at the point where the incident ion deposits charge with a temperature rise which can explain melting of used materials.

The new power semiconductor generation: 1200V IGBT4 and EmCon4 Diode

This paper presents Infineonpsilas latest 1200 V power semiconductor generation: IGBT4 and EmCon4 diode. The new technology comes as a family optimized for applications in three different power levels: low, medium, and high power. Each part is balanced accordingly in its dynamic and static losses, switching frequency, and softness. In this paper the new technology is introduced, the electrical and thermal performance discussed in detail.

Tailoring of field-stop layers in power devices by hydrogen-related donor formation

Hydrogen-related donors can be formed by using only a moderate thermal budget, so that this process can be used to create field-stop layers in thin power devices. The electrical characteristics of 1200 V IGBTs and diodes provided with such field-stop layers are presented and compared with the characteristics of conventionally processed devices. Moreover, tailoring the field-stop distribution by multi-energy proton implantations offers new opportunities for optimizing the performance of power devices.

Predictive physical model of cosmic-radiation-induced failures of power devices

In the last ten years, the hardening of silicon high power devices against cosmic-radiation-induced failure gained decisive importance. A systematic improvement of the robustness against cosmic radiation requires a fundamental physical understanding of the microscopic mechanisms which lead to the failure or even destruction of power devices. We performed detailed 3D thermo-electrical device simulations to study the local self-heating in the device in order to explain the failure and destruction mechanisms and compared the results with experimental data obtained from nucleon irradiation experiments. Several diode designs with varying doping concentration and vertical size of the device were investigated.

Carrier lifetime characterization using an optimized free carrier absorption technique

We investigated the correlation of the high-level lifetime of platinum-diffused power diodes with the platinum diffusion temperature, varying over a range of 40 K, and the operating temperature, varying from 223 K to 398 K. The high-level lifetime has been extracted from carrier profiles determined by an optimized free carrier absorption technique, assuming a homogeneous lifetime over the base region. We find an exponential dependence of the high-level lifetime on the operating temperature and no dependence of the injection levels under investigation. Therefore, the recombination processes can be properly described by using the Shockley-Read-Hall model in the electrothermal device simulation. The mean high-level-lifetime for a calibrated device simulation is only 20% lower than the experimentally determined one. The simulated carrier distributions are in very good agreement with the experiment if a weak lifetime gradient in the base region is assumed.

Reliability aspects of copper metallization and interconnect technology for power devices

Abstract The introduction of thick copper metallization and topside interconnects as well as a superior die attach technology is improving the performance and reliability of IGBT power transistor technologies significantly. The much higher specific heat capacity and higher thermal conductivity increases the short circuit capability of IGBTs, which is especially important for inverters for drives applications. This opens the potential to further optimize the electrical performance of IGBTs for higher energy efficiency. The change in metallization requires the introduction of a reliable barrier against copper diffusion and copper silicide formation. This requires the development of an efficient test method and reliability assessment according to a robustness validation approach. In addition, the new metallization enables interconnects with copper bond wires, which yield, together with an improved die attach technology, a major improvement in the power cycling capability.

Novel emitter controlled diode with copper metallization in ultrathin wafer technology: Setting a performance benchmark

Electrical characterization results (e.g. softness, cosmic ray hardness, surge current) of a novel freewheeling diode with reduced thickness and copper metallization are shown.

Power Cu metallization for future power devices — Process integration concept and reliability

A novel power Cu front side chip metallization for insulated-gate bipolar transistors (IGBTs) and freewheeling diodes (FWDs) enabling thick Cu wire wedge bonding on active area is reported. In the continuing race to higher power density, main limitations of IGBT power modules are given by short circuit robustness requirements of the IGBT and power cycling capability of the front side Al wedge bond interconnect. Both topics are addressed by Infineons 5th Generation of IGBT with XT joining technology [1, 2] enabling power density steps far beyond 30%. The developed Cu metallization with a special barrier layer structure allows Cu wedge bonding with high yield and extremely high reliability. The paper is describing firstly the device fabrication and secondly a novel reliability testing method (based on wafer level) covering the possible impact of the wire bond process.