Experimental Study on SOI LIGBT with Field Plate Resistances at Anode Side

A novel snapback-free SOI LIGBT with Field Plate Resistances (FPR) is proposed and experimentally investigated. The FPR consisting of multiple polysilicon resistances 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. 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 turnoff loss ( $E_{\text{off}}$ ). A 439V FPR SOI LIGBT is fabricated and decreases the $E_{\text{off}}$ by 36% at the expense of 7% increasement in on-state voltage drop ( $V_{\text{on}}$ ) compared with the conventional SOI LIGBT. The experimental results show that the proposed FPR SOI LIGBT could achieve a good tradeoff relationship between the $E_{\text{off}}$ and $V_{\text{on}}$ .