[show abstract][hide abstract] ABSTRACT: We derive an efficient and accurate computer-aided-design-based design methodology for the optimization of floating field-limiting ring terminations. The proposed approach is based on an iterative optimization of the ring-to-ring spacings starting from the outermost ring and proceeding back toward the main junction. Physics-based simulations show that each optimization step does not impair the previous one, thus allowing to easily identify the minimum number of rings needed to achieve the desired termination efficiency yet minimizing the number of simulation steps. The accuracy of the method is thoroughly discussed on the basis of comparisons against either literature results or experimental data.
IEEE Transactions on Electron Devices 02/2011; · 2.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this paper, we present a quantitative study of the effects of lifetime engineering treatments on the switching operation of power diodes, with special regards to the whole energy consumption. Not only single platinum diffusion and helium implantation processes, but also the combined effects for both treatments have been analyzed. Results show that care must be taken when choosing the lifetime treatment because univocal rules are difficult to draw.
IEEE Transactions on Electron Devices 12/2009; · 2.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this paper, a study of the effects on both lifetime and resistivity, induced by helium implantation processes, is presented. A wide range of implantation energies (from 3.5 MeV to 5.8 MeV) and doses (from 1middot108 atm/cm2 to 2middot1011 atm/cm2) is considered and, for each of them, the resistivity profile and the lifetime profile are measured and compared with that of the unprocessed material. Moreover, the temperature dependence of that profile is analysed in the usual operation range of power devices. Results show that a high helium dose not only reduces the recombination lifetime but significatively affects the resistivity too. The temperature dependence of the two parameters is such that they play different roles at high or low temperature
[show abstract][hide abstract] ABSTRACT: The paper presents the results of the application of physics-based mixed-mode simulations to the analysis and optimization of the reverse recovery for Si-based fast recovery diodes (FREDs) using Platinum (Pt) lifetime killing. The trap model parameters are extracted from Deep Level Transient Spectroscopy (DLTS) characterization. The model is validated against experimental characterization carried out on the current International Rectifier (IR) FRED PiN technology. Improved designs, using emitter control efficiency and merged PiN–Schottky structures, are analyzed. Comparison between simulated and measured results are presented.
[show abstract][hide abstract] ABSTRACT: In this work we present an experimental study on the effects of helium implantation in silicon. Doses in the range 1 times 10<sup>10 </sup> - 5 times 10<sup>11</sup> atoms/cm<sup>2</sup> have been analysed. Results show that, increasing the dose, a saturation effect on the minimum lifetime that can be achieved occurs, while a marked effect on the resistivity of the material appears. The temperature dependence of the resistivity show that changes are due to a trap effect related to an energy level in the bandgap placed at Ec-0.23 eV that is the same of the dominant recombination center induced by helium implantation
Power Semiconductor Devices and ICs, 2005. Proceedings. ISPSD '05. The 17th International Symposium on; 06/2005
[show abstract][hide abstract] ABSTRACT: Recent studies suggest that lattice damage induced by helium or proton ion implantation can be used to control the electrical behavior of bipolar semiconductor devices, such damage directly affecting the mean time (lifetime) of electrons and holes over and above their equilibrium values. However, a lack of knowledge exists regarding the nature of the defects produced by ion implantation, in particular, their stability with time and temperature and effectiveness in controlling recombination processes.In this paper we have reconstructed and characterized the damage profile induced by helium implantation in silicon by making direct measurements of the lifetime profile made on specially fabricated test devices. Results show that the shape of the defect profile differs from that predicted by Monte Carlo simulations. Also, a considerable increase in the resistivity of the layer, not expected with He implantation, has been found. Finally, energy levels affecting the recombination of minority carriers have been given.
[show abstract][hide abstract] ABSTRACT: The distribution of recombination centers induced in Si epi-substrates by helium (He) implantation is obtained for the first time by direct measurement of local recombination lifetime profile along the layer, using the ac differential lifetime profiling technique. The different energy levels of the recombination centers induced by He implantation at different doses and energies have been extracted, as a function of the position in the layer, by temperature scanning of the lifetime profiles. The lifetime measurements clearly demonstrate the presence of a secondary defect distribution that extend from the region of maximum primary damage both at lower and higher depths respect to the stopping range depth, due to the relatively large concentration of primary defects created near the stopping range, and give a coherent picture of the effects of He implant on the "local" lifetime.
IEEE Electron Device Letters 10/2004; · 2.79 Impact Factor