| Monolithic integrated intelligent power chip is applied in household appliances and motors now.As one of the most important devices in monolithic integrated intelligent power chip,SOI-FRD is used as the freewheeling diode.For the further development of monolithic integrated intelligent power chip,the power consumption and area of SOI-FRD need to be optimized.Therefore,it is necessary to study and design a new SOI-FRD with excellent reverse recovery characteristics.Firstly,the working principle of conventional SOI-FRD are discussed and studied by theoretical analysis and simulations.Secondly,a few simulations of different structures are carried out,which show that Deep Oxide Trench(DOT)technology can speed up reverse recovery process,but waveform oscillation of the diode is observed and the process of DOT are hard.Diode's reverse recovery characteristics can be improved by Junction Barrier Schottky technology,but its breakdown voltage gets decreased.Diode's reverse recovery features can also be made better by Self-Adjusting p Emitter Efficiency technology,but on-set voltage of diode is too high.So a new SOI-FRD with multiple deep oxide trenches on thick SOI is proposed.Multiple deep oxide trenches are applied in the new structure,which realizes 603 V breakdown voltage.And the length of drift area is shorter than that in the conventional structure,which reduces the region and size of device to optimize device's reverse recovery rate and on-set voltage.Multiple deep oxide trenches can avoid dynamic punch-through and more holes can be captured during reverse recovery process,which is beneficial to increasing the reverse recovery softness factor.Finally,the process and layout of the proposed structure are designed.The test results show that breakdown voltage of the proposed structure is 603 V,forward turn-on voltage is 1.2V,reverse recovery time is 122 ns,and waveform doesn't oscillated.Compared with the similar product,the reverse recovery time of proposed structure reduces by 28 ns. |
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