New Structures Of Power Schottky Rectifiers And The Simulation Research

Schottky Barrier diodes (SBD) work on the contact barrier between the metal andsemiconductor. It is widely used as high frequency rectifier, detection and frequency mixingat low power, large electronic current output occasions. Nevertheless, the reverse breakdownvoltage of Silicon SBD is quite low at present. In order to reduce the specific on-resistanceand improve the reverse voltage capability of the device, some new type structures aredesigned and we obtain improved power Schottky with high performance, low powerconsumption, low cost and high reliability.In this work, the design of the power Schottky device structure and the investigation ofthe performance simulation technology are carried out in the two-dimensional devicesimulation software Silvaco TCAD. The theory and performance of Schottky barrier diode(SBD) are studied. The important electrical indicators of power Schottky diode are specificon-resistance, reverse blocking voltage, reverse leakage current, reverse recoverycharacteristics and output capacitance. These features are the most important indicators for theperformance, cost and reliability of the power Schottky. In addition for super junctionSchottky barrier diode, the charge balance is very important. In order to improve thesefeatures in this work, some new structures of power Schottky barrier diode are proposed toimprove the contradictory relationship of power Schottky diodes between conduction lossesand switching costs:(1) A novel trench MOS barrier Schottky rectifier with a variable K dielectric layer(VK-TMBS).VK-TMBS shows the increasing forward current density and the reduction in specificon-resistance (Ronsp), as compared to a regular trench MOS barrier Schottky (TMBS) rectifier.VK-TMBS attains a breakdown voltage of140V, which is larger than that of the originalTMBS. The forward voltage drop of TMBS is0.64V at180A/cm2, and that of VK-TMBS is0.59V. The Rsp of VK-TMBS is26.7%smaller than that of the TMBS. The numericalsimulation results indicate that the proposed device features high performance with animproved figure of merit.(2) A super junction Schottky barrier diode with trench metal-oxide-semiconductor(MOS) structure (TM-SJ-SBD).TM-SJ-SBD is proposed and studied by two-dimensional numerical simulations. Thedevice shows the decreasing leakage current compared to the common super junction Schottky barrier diode (SJ-SBD) without considerable degradation of forward characteristics.With optimized parameters, TM-SJ-SBD attains a breakdown voltage of178V, which issimilar to the SJ-SBD, and a leakage current of1.57×10-5A/cm2at130V reverse bias, whichis46.5%smaller than that of the SJ-SBD. In addition the TM-SJ-SBD achieves softer reverserecovery characteristics, the reverse recovery charge of TM-SJ-SBD is54.2%reduction thanthe SJ-SBD and the reverse recovery peak current is67.9%reduction than that of the SJ-SBD.(3) A super junction Schottky barrier diode with double layer (DSJ-SBD). These threetypes of Schottky barrier diode are proposed to improve the performance of Trench MOSBarrier Schottky (TMBS) and super junction Schottky barrier diode (SJ-SBD).DSJ-SBD is designed with double layer super junction. DSJ-SBD improves thebreakdown voltage at charge imbalance and DSJ-SBD shows the decreasing outputcapacitance and reverse recovery peak current. The new structure can reduce the static anddynamic losses. Due to the low level doping layer super junction, DSJ-SBD can improvebreakdown voltage with the same charge imbalance. The depth of the doble layer superjunction is a very important parameter and it is studied and discussed.