Research On The Quasi Super Junction Devices With Optimized Electric Flux Distribution

Power electronics technology is a key part in the application of electric power.As the basis of power electronics technology,the development of power electronic devices aiming at lower energy consumption and lower cost is of great significance to save Resources and protect Environment.For the power semiconductor devices,optimization of the breakdown voltage?V_b?,on-state voltage drop(V_on)/specific on-resistance(R_on,sp),switching loss(E_swiching)and other performance can satisfy these goals.However,the Metal Oxide Semiconductor Field Effect Transistor?MOSFET?faces a contradiction between increase in V_b and decrease in R_on,sp.Techniques like Super Junction?SJ?and a series of quasi SJ techniques,including Oppositely Doped Island?DOI?and High-K?HK?dielectric modulation are proposed to solve this problem.These techniques can optimize the tradeoff between V_b and R_on,sp in MOSFET.SJ technique achieves the best performances.However,the other two techniques are superior in simple fabrication process and high tolerance to the process deviations.Besides,the Insulated Gate Bipolar Transistor?IGBT?faces a contradiction between reduction in V_on and decrease in turn-off loss(E_off).Likewise,the application of SJ in IGBT can optimize this tradeoff.However,considering the complicated fabrication process of SJ technique and its strict requirement of charge balance,its application in IGBT will be difficult.Based on the above problems,this paper analyzes the optimized electric flux distribution in the voltage-sustaining region of the devices using quasi SJ techniques,such as DOI and HK dielectric modulation,and does researches on their applications in IGBT.The main contents are as follows:1.A novel IGBT with Oppositely Doped Islands?DOI-IGBT?is proposed.After analyzing the structure of DOI in IGBT,and simulating the DOI-IGBT,it is found that DOI can increase V_b of IGBT.Besides,DOI reduces E_off of IGBT by 12%because it helps the drift region deplete rapidly during the turn-off transient.By thinning the DOI-IGBT,it can obtain a turn-off loss 52%lower than the field stop IGBT?FS-IGBT?with the same V_b.2.A novel IGBT with High-K dielectric modulation?HK-IGBT?is proposed.By adding an HK dielectric between Gate and the drift region of IGBT,the effect of electric flux transferring is obtained in the drift region by the HK dielectric,and the Gate-drift capacitance is increased.Therefore,the voltage-sustaining capability of IGBT is improved.However,the on-state current of HK-IGBT is lower than FS-IGBT because the HK dielectric occupies the conductive path.Besides,the depletion of the drift region accelerates in the turn-off transient due to the HK dielectric,and the current tail completely disappears.Hence,E_off of HK-IGBT is 66%lower than that of FS-IGBT.After the introduction of the carrier stored layer,the on-state characteristic of HK-IGBT can be improved.In this case,HK-IGBT obtains an E_off 86%lower than FS-IGBT.3.Based on the HK-IGBT,a novel IGBT with High-K dielectric film and Si O₂?HKF-IGBT?is proposed.Because HK dielectric film can have better quality and characteristics than HK dielectric pillar under the current technology,the HKF-IGBT is more feasible.Although the thickness of the HK dielectric film is only 400 nm,the effect of HK dielectric modulation can be enhanced by increasing the permittivity of the dielectric.Therefore,the voltage-sustaining capacity of HKF-IGBT is still higher than FS-IGBT,and its turn-off loss can be reduced by 62%.Moreover,compared to HK-IGBT,the signal fluctuation during the turn-off transient of HKF-IGBT is slighter.4.Based on the HK-IGBT,a novel IGBT with Part of the effect of High-K dielectric modulation?PHK-IGBT?is proposed.The feature of PHK-IGBT is that the thickness of HK dielectric is only half of the thickness of the drift region.This device has three advantages.First,the HK dielectric modulation achieves a flat and uniform electric field distribution in the voltage-sustaining region,and increases V_b of IGBT.Second,HK dielectric increases the Gate-drift capacitance and the carrier concentration of the drift region at on-state,and reduces V_on of IGBT.Third,HK dielectric accelerates the depletion of the drift region in the turn-off transient and reduces the turn-off loss of IGBT.By adding another HK dielectric with higher permittivity between Gate and the previous HK dielectric,the device can have a better optimization on the tradeoff between V_on and E_off,and the E_off is reduced by 57%compared to that of FS-IGBT.