Study On Mechanism And Characteristics Of Thin SOI-based High-speed And Low-power IGBT

The rapid development of modern industry and high-tech technology urgently needs the supply of power energy.Power semiconductor devices,as the mainstay of supporting the efficient use of energy and the environmentally friendly use of energy,assume the pivotal role of power conversion and support the major strategic development of the country.Insulated gate bipolar transistor?IGBT?device is a compound full-control,voltage-driven power device that combines the advantages of field effect transistors and bipolar junction transistors,which owns large input impedance,low driving power,and low on-voltage(V_ON)and has been widely used in green energy,rail transportation,high-voltage power grid transmission,and industrial automation.Thin-film lateral IGBT based on Silicon-on-Insulator?SOI LIGBT?is a new type of IGBT,which provides significant advantages for conversion systems based on power converters in terms of energy efficiency,cost,integration miniaturization,and stability.However,due to the conductance modulation caused by the large injection effect,the V_ONN is improved,and the turn-off loss(E_OFF)is limited.The contradiction of thin-film LIGBT between the V_ON and the E_OFF is particularly serious,and the saturation current capability is weak,which limited by the influence of the Si-SiO₂ interface recombination and the equivalent JFET region.Under the guidance of theory and technology,this paper proposes two new thin-film SOI-based LIGBT devices to address the scientific problems,focusing on the improvements of saturaturation current capability,breakdown voltage?BV?,fast switching,and low loss.1.Based on the concept of carrier storage technology and variation of lateral doping?VLD?theory,a new thin film SOI LIGBT with a thickened drift region and folded trench gate is proposed.The device is characterized by a stepped thickened drift region and a folded trench gate.In the forward blocking process,the constant dopped drift region owns impurities with a laterally varied distribution,thereby achieving high blocking voltage.In the conduction process,the SiO₂ near the cathode compresses the drift thickness and acts as a dielectric barrier?DB?,which hinders the hole from being collected directly by the cathode,enhancing the conductance modulation effect and reducing V_ON.The introduction of the folded trench gate greatly increases the effective channel density within limited chip area.And the T-shaped P+cathode region improves hole collection efficiency and vertical channels provide low-resistance for hole,thus improving the latch-up immunity and short-circuit capability.The simulation results show that compared with the traditional structure,the new device has an increase of 53%in the E_OFF under the same V_ON and an increase of 23%in the V_ON under the same E_OFF.At higher operating currents?200A/cm²?,the V_ON of the new device is improved by 38%,which has a better overall performance.The saturation current density of the new structure is increased by 250%compared to the traditional structure,and the short-circuit time increased by 60%.2.Based on the carrier injection enhancement technique?IE?and theory of the anode potential control technique,a new high-speed,low-power-consumption thin film SOI LIGBT device with dual localized oxide grooves is proposed.The new structure owns low V_ON,fast turn-off capability,and compatibility with CMOS processes.The use of LOCOS avoids the difficulty of thin film etching and ensures the quality and reliability of the film.The new structure uses linear variable doping technology to achieve high breakdown voltage.During the forward conduction,the LOCOS trench beneath gate compresses the carrier path extremely,and acts as a dielectric barrier to hinder holes.And the high-concentration electron accumulation layer?EAL?as an injection source injects electrons into the drift region to enhance the conductance modulation effect,and thus reducing the V_ON.And the LOCOS groove in the anode region separates P+and N+in space to avoid a decrease in hole injection efficiency.The path from the N+region to the buffer layer is extremely compressed by this groove,which enlarges the anode distribution resistance,avoiding snapback phenomenon during conduction.During the turn-off process,the N+provides a fast extraction path for electrons,which speeds up the switching speed and effectively improves the problem of tail current.The simulation results show that compared with the traditional structure,the new device improves the E_OFF by 40%under the same V_ON and the on-voltage drop by 25%under the same E_OFF.In addition,the new structure reduces the time of tail current from 174ns to 84ns.Compared with the traditional structure,the saturation current density of the new one has increased by 23%and the short-circuit time has only increased by 13.6%.