Non-full Depletion Mode And Its Experimental Realization Of The Lateral Superjunction

Superjunction?SJ?transfer the surface electric field into the body by introducing equivalent amount of balanced charge into the drift region,realizing the revolutionary transformation from the traditional resistance type sustaining-voltage layer to the junction type sustaining-voltage layer.The theory proves that the vertical super junction device reduces the"silicon limit"relationship R_on,sp?V_B^2.5 of the conventional power MOS device to R_on,sp?V_B^1.32,which is called the"milestone"of the power semiconductor device.The theoretical study shows that the vertical superjunction has the lowest specific on resistance when the drift region is not completely depleted.However,the non-depletion mode and minimum specific on-resistance have not been reported.The proposal of the Equivalent Substrate?ES?model has provided theoretical guidance to solve the SAD?Substrate assisted Depletion?effect of lateral superjunction devices,but this model is only in the theoretical stage at present,and no experimental reports have been reported.The significance of the study on the NFD mode of the lateral superjunction devices is to explore the performance limits that can be achieved by lateral superjunction devices,and narrow the gap between the actual production and theoretical limits.The main work,innovation points and related achievements of this paper are as follows:Firstly,the new working mode of NFD for vertical superjunction devices is introduced into the lateral superjunction devices for the first time.The charge field modulation effect in the vertical superjunction devices is used to analyze the lateral superjunction devices,and the lateral superjunction devices worked in the mode of non-full depletion are designed by learning superjunction devices and related literatures and the current technologies of LDMOS,the results show that the device has lower specific on-resistance under non-full depletion mode.Secondly,the equivalent substrate for the optimization of SOI-based lateral superjunction devices is designed and verified.Guided by equivalent substrate model gives the lateral superjunction device ideal substrate design thought,based on this,proposed a SOI ES-SJ LDMOS?Equivalent substrate-Superjunction LDMOS?new structure with an ideal substrate,the structure by optimizing the drift region doping method to achieve the ideal substrate,and the simulation verify this method can suppress the SAD effect completely,and obtain approximate rectangle of the electric field distribution,to ensure the lateral superjunction device the sustaining-voltage capacity at the same time as provides the ideal boundary conditions for the stack of the super junction.Finally,a lateral superjunction device with an ideal substrate worked in the non-full depletion mode is realized,and the experiment proves that lower R_on,sp in a non-full depletion mode and the accuracy of equivalent substrate model.The designed and optimized SOI-based ES-SJ LDMOS device has a test breakdown voltage of 477V,and the LDMOS device without superjunction has a test breakdown voltage of 484V.The experiment verifies that the proposed ideal substrate implementation method can completely suppress SAD effect.R_on,,sp is 30.9 m?·cm²,compared with the published experimental results,ES-SJ LDMOS device was reduced by 67.8%under the condition of the same voltage,compared with the traditional RESURF Triple condition was reduced by 28.4%,the experiment verifies the existence of the NFD mode with better performance.