Novel Structure Design And Performance Research On Silicon-on-Insulator Lateral Insulated Gate Bipolar Transistor

Insulated Gate Bipolar Transistor?IGBT?has advantages of Bipolar Junction Transistors and Metal-Oxide-Semiconductor Field-Effect Transistors.It is easy to control,and has low conductive voltage,high current density and breakdown voltage.It is one of the most important power semiconductor devices.Lateral IGBT?LIGBT?is the combination of IGBT,integrated circuit technique and silicon-on-insulator?SOI?technology.SOI-LIGBT is widely used in power management,various electronic equipment drives and smart switches due to its higher integrity,lower power consumption,more excellent isolation.Although the market demand of SOI-LIGBT is powerful,the technology of SOI-LIGBT is monopolized by a few foreign enterprises.Therefore,research on the higher performance SOI-LIGBT is very significant with national policy of vigorously developing semiconductor industry.High performance SOI-LIGBT needs faster turnoff speed,lower turnoff loss,lower conductive voltage and higher current density.In this dissertation,firstltly,relationship between the snapback and the anode region resistance in the shorted anode structure is studied.Then relationship between the excess carriers and variation of lateral doping?VLD?layer during inductive load turnoff stage is studied focusing on the tradeoff between turnoff loss and conductive voltage.Finally,the trigger and quit mechanism of latch up effect is studied.Therefore,three kinds of new structures are proposed in order to improve the performance of SOI-LIGBT.The main contents and innovations are as follows:1.Two kinds of SOI-LIGBT with the improved anode region are proposed,which can increase the turnoff speed,save the anode region area,suppress and eliminate snapback phenomenon.?a?SOI-LIGBT with L-shaped extraction path?LEP SOI-LIGBT?.L-shaped electron extraction path is achieved in the N-buffer region through the location of P buried layer,P+region,N+region in the anode region.Thus sufficient high R_SAis achieved in the less anode region area.During on-state stage,the electron current flows through the sufficient big resistance R_SA,and it thus make the P+/N-buffer junction turn ON avoiding snapback phenomenon.During off-state stage,the excess electrons in the drift region near the anode region are extracted rapidly through the L-shaped extraction path,hence the faster turnoff speed is achieved.The influence of the key parameters of L-shaped extraction path on the forward characteristics is analyzed in depth.Compared with STA SOI-LIGBT and SSA SOI-LIGBT,the anode region area of the LEP LIGBT reduces by 63%and 77%,respectively,and the turnoff time reduces by 40%and 28%,respectively,at conductive voltage of1.23V.?b?SOI-LIGBT with double L-shaped extraction path?DLP SOI-LIGBT?.Based on the LEP SOI-LIGBT,the structure includes the polysilicon L-shaped extraction path,forming double L-shaped extraction path in order to decrease the anode region area.DLP SOI-LIGBT eliminates snapback phenomenon with the same device length of the conventional SOI-LIGBT.Compared with the conventional SOI-LIGBT,the simulation reveals that the turnoff loss and the turnoff time of DLP SOI-LIGBT reduces by 23%and about 39%,respectively.2.Two kinds of SOI-LIGBT with the improved drift region are proposed,which can improve the tradeoff between turnoff loss and the conductive voltage.?a?SOI-LIGBT with p-typed buried variation of lateral doping layer.P-typed buried variation of lateral doping layer is introduced into the conventional LIGBT in this structure.The influence of the key parameters of p-typed buried variation of lateral doping layer on the turnoff characteristics is analyzed.The proposed simple model of d V/dt reveals that doping dose and gradient produce a marked effect on the assistant depletion of the buried layer and the extraction of excess carriers while keeping the breakdown voltage.Compared with UPB SOI-LIGBT,the turnoff loss reduces by 29.4%at the conductive voltage of 1.13 V(current density of 100A·cm^-2),and reduces by 69.4%at the conductive voltage of 1.3 V(current density of 200A·cm^-2).?b?Trench gate SOI-LIGBT with p-typed buried variation of lateral doping layer?TG VLD SOI-LIGBT?.P-typed buried variation of lateral doping layer is introduced into the trench gate SOI-LIGBT.Simulation results show that turnoff loss of TG VLD SOI-LIGBT reduces by 65.3%and24.2%,respectively,compared with TG SOI-LIGBT and UPB TG SOI-LIGBT at the conductive voltage of 1.01V(current density of 100A·cm^-2).3.SOI-LIGBT with self-biased PMOS?SP SOI-LIGBT?with the improved cathode region is proposed,which can increase the current density of device.Combined the inserted self-biased PMOS with NMOS in the cathode region,lower anode voltage can trigger latch up effect.Consequently,the carrier concentration distribution results in higher current density.Through mechanism analysis and simulation software,the influence of the key parameters of self-biased PMOS on the forward characteristics is analyzed in depth.At the conductive voltage of 2.59V,the current density increases by 47%compared with the conventional SOI-LIGBT;the turnoff loss of SP SOI-LIGBT reduces51.28%,66.15%and 83.17%at the current density of 100A·cm^-2,300A·cm^-2 and 500A·cm^-2respectively,compared with the conventional SOI-LIGBT.Therefore,the tradeoff between turnoff loss and conductive voltage achieves large improvement.