Lateral Power Device Vertical Electric Field Modulation Mechanism And New Device Design

As a critical component in power ICs,lateral power devices have always been the focus and focus of research for related practitioners.The device's breakdown voltage and turn-on performance are the most critical factors for high-voltage integrated circuits,and the optimization techniques at home and abroad for lateral power devices have never stopped.Also in the process of device optimization,the problem of vertical breakdown voltage limitation of lateral power devices becomes more and more prominent.The REBULF theory and electric field modulation techniques,etc.,provide guidance for the optimization of power device performance.Based on this and combined with the optimization process of power device,this paper proposes the theory of vertical electric field modulation of the lateral power device and optimizes the vertical electric field of the lateral power device.Based on this,two new device structures are proposed,ADSL LDMOS and ADSL SJ-LDMOS.For the problem of vertical pressure limitation of the lateral power device,this paper proposes a kind of solution.The specific innovations in this paper include:(1)By analyzing the optimization technical ideas of the bulk and vertical electric field optimization ideas of lateral power devices,combined with REBULF theory and electric field modulation technology,etc.,aiming at optimizing the vertical electric field distribution of lateral power devices and solving the problem of vertical pressure limitation,On the basis of the above-mentioned optimization theory of vertical pressure limitation and structural optimization,the vertical electric field modulation theory of the lateral power device is proposed.This theory optimizes the vertical electric field of the lateral power device,fully exploits the breakdown voltage capability of the device substrate,alleviates the breakdown voltage saturation of the lateral power device,optimizes the vertical electric field distribution of the device,and also has a sufficient optimization effect on the surface electric field.Proposed a new theory for the lateral power device vertical pressure problem.(2)Combining the optimization theory and structure optimization of vertical breakdown voltage,and based on the theory of vertical electric field modulation of lateral power devices proposed in this paper,a novel LDMOS structure with vertical assisted deplete substrate layer is proposed for the typical lateral power device LDMOS.Research shows that when the lengths of the drift regions of conventional LDMOS and ADSL LDMOS are both 70?m,the breakdown voltage increases from 462V to 897V,an increase of about 94%,and Figure-Of-Merit(FOM)is also increase from 0.55 MW/cm~2 to 1.24 MW/cm~2,an increase of 125%.Therefore,the device performance of the new structure ADSL LDMOS has been greatly improved compared to the conventional LDMOS.Furthermore,the ADSL layer is optimized by partitioned doping optimized.Based on the new structure,the breakdown voltage rises to 938V in the double partition and 947V in the three partitions.At the end of this chapter,the detailed process of the process preparation technology for the new structure device is given.(3)On the basis of a novel LDMOS structure with vertical assisted depleted substrate layers,applying the vertical electric field modulation technology and lateral super-junction power devices,a new type of SJ LDMOS structure with vertical assisted deplete substrate layer,namely ADSL SJ-LDMOS,is proposed.Research shows that the newly proposed ADSL SJ-LDMOS increases the breakdown voltage from 273V to 445V when the length of the drift region and the conventional SJ-LDMOS are both 30?m,an increase of about63%,and a merit FOM also from 3.764MW/cm~2.Increased to 6.828MW/cm~2,an increase of 81.4%.