Device Design And Mechanism Study Of Novel High-voltage Low-power IGBT

LIGBT（Lateral Insulated Gate Bipolar Transistor）not only has the advantages of low conduction loss and high input impedance,but also is easy to integrate in the chip.Thanks to the conductance modulation effect,LIGBT has a low on-state voltage drop(V_on),which is accompanied by a large turnoff loss(E_off)due to the large number of carriers stored in the drift region.To solve this problem and optimize the V_on-E_offtradeoff relation of LIGBT without introducing snapback phenomenon,two new LIGBT structures are proposed in this thesis.1.A novel snapback-free SOI LIGBT with Field Plate Resistances（FPR）is proposed and experimentally investigated.The FPR consisting of multiple polysilicon resistors is located above the field oxide at the anode side,which is compatible with the planar poly gate design.The two sides of FPR are connected with the P+anode and N+anode,respectively.Hence,the FPR not only effectively increases the anode distributed resistance to eliminate the snapback effect in the on-state,but also provides an electron extraction path during the turnoff period to accelerate the turning off and decrease the E_off.A 439V FPR SOI LIGBT is fabricated and decreases the E_offby 36%at the expense of 7%increasement in V_oncompared with the conventional SOI LIGBT.Thus,the proposed FPR LIGBT could achieve a good tradeoff relationship between the E_offand Von.2.A novel SOI lateral insulated gate bipolar transistor（LIGBT）featuring a U-shape trench anode（UTA）is proposed and investigated.The UTA consists of P+anodes,N+anode and U-shape P-region,and the N+anode connects to the N-buffer through a low doped N-region.In the on-state with low anode voltage（V_A）,the N-region is depleted by the U-shape P-region to increase the anode distribution resistance and thus suppress the snapback effect.During the turnoff period with V_Aincreasing,the depleted N-region turns into neutral region to form an additional electron extracting path to decrease the E_off.Therefore,the UTA LIGBT obtains better tradeoff relationship between E_offand V_on.In the blocking state,the UTA LIGBT exhibits a MOS breakdown mode instead of an open base PNP bipolar breakdown mode.Compared with separated shorted anode（SSA）LIGBT at the same current density of 100A/cm2,the UTA LIGBT decreases the E_offby 71.6%at the same V_onand reduces the V_onby 23.1%at the same E_off,respectively.