Research And Design Of The Safe Operating Aera Of SOI-LDMOS Based On Thick Film Process

Due to the advantages of low power consumption,high reliability,low cost and other advantages,intelligent power chips are widely used in power management,intelligent switches,motor drives,linear regulators,etc.Silicon on insulator-lateral diffused metal oxide semiconductor(SOI-LDMOS)is an important component of high voltage level conversion circuit in intelligent power chip.This requires SOI-LDMOS not only has high breakdown voltage and low on-resistance,but also must have a wide safe operating area.On the SOI substrate with poor heat dissipation performance,it is difficult to expand the safe operating area.This thesis analyzes the trigger mechanism of electric safe operating area and thermal safe operating area,and through the traditional LDMOS structure simulation discovered reasons.The electric field of the surface of silicon below drain field plate reaches the critical electric field value restriction electrical safe operating area,and thermal safe operating area is influenced by the parasitic transistor opened.While comparing the advantages and disadvantages of advanced technology,this thesis proposes a Step Partial SOI with P-type buried layer(PSP-LDMOS),the structure adopts the thin oxide layer deposition on P buried layer,to increase cooling device and extend the current path,realize the wide safe operating area.Finally,this thesis design the process and layout of the new structure.The test results showed that the electric safe operating area E-snapback voltage is 563V,the thermal safe operating area of on-state breakdown voltage is 475V,the range of thermal safe operating area is 4.06W/?m,and other electrical parameters such as on resistance have been optimized to improve,which meets the requirements of 550V power drive chip.