Study And Design Of Novel High Voltage LDMOS Structure Based On SiC/Si

High voltage LDMOS?Lateral Double-diffused MOSFET?is the key device of power electronic equipment and power electronic system.It has the characteristics of high withstand voltage,high power,large current,easy integration,compatibility with CMOS process,etc.It is widely used as switching devices in power integrated circuits,and its key performance indexes are breakdown voltage and specific on-resistance.Si-based power MOS devices are the main commercial semiconductor power devices at present,but there is a contradiction of 2.5 power between the breakdown voltage and the specific on-resistance,which restricts the full play of the performance of Si-based power devices,and its development is limited by the"silicon limit".As a typical representative of the third generation of wide band gap semiconductor materials,SiC is widely concerned because of its advantages such as wide band gap,high critical breakdown electric field,strong radiation resistance,high thermal conductivity and other advantages.SiC-based MOS devices have better characteristics than Si-based MOS devices,but due to the particularity of the materials,the traditional silicon process is not completely applicable for the manufacturing of SiC devices,and the manufacturing process of SiC MOS devices still has many unstable key points of processes.In order to solve these problems faced by semiconductor power devices and obtain high-performance semiconductor power devices?high withstand voltage,low power loss,and large current?,based on the research of SiC/Si heterojunction,the following three novel high-voltage LDMOS structures are proposed:?1?A novel SiC/Si heterojunction LDMOS with reversed L-shaped field plate.Modulating the lateral and vertical electric field distribution of the device by introducing the reversed L-shaped field plate and the stepped oxide layer,and utilizing the high critical breakdown field,the high thermal conductivity of the SiC material and the mature silicon technology to improve the performance of device and the tradeoff between the breakdown voltage?BV?and the specific on resistance(R_on,sp).The simulation results show that,the BV of this device is increased from 226V and 720V to 992V compared with the conventional Si LDMOS and SiC LDMOS respectively,while maintaining a low specific on-resistance R_on,spof 27.62m?·cm².?2?A trench gate SiC/Si heterojunction LDMOS with a channel accumulation layer.A high concentration channel accumulation layer is introduced in the drift region to provide a low resistance carrier transport path.Combining the advantages of SiC and Si materials,the device further achieves high breakdown voltage BV and low specific on-resistance R_on,sp.The simulation results show that the device achieves a high breakdown voltage?BV?of1060V and a low specific on-resistance(R_on,sp)of 8.9 m?·cm².Compared with the conventional Si LDMOS and SiC LDMOS,the BV of this device increased by 832V and339V respectively.?3?A thin drift region SI-SiC/Si LDMOS with a semi-insulating SiC buried layer,by adopting semi-insulating?SI?SiC material to replace the Si O₂ layer in the SOI structure and utilizing the high thermal conductivity and high critical breakdown electric field of SiC to achieve high breakdown voltage and effectively solve the heat dissipation problem of SOI LDMOS device.The simulated results have indicated that this device achieves a 200V level withstand voltage of the same size structure,and obtains a breakdown voltage?BV?of 236V and a specific on-resistance(R_on,sp)of 4.0m?·cm².Compared with conventional SOI-based structure and Si-based structure,the specific on-resistance decreased by 30.6%and 54.4%,respectively,and the FOM increased by 87.8%and 157.4%.The surface temperature of the device decreased by 118K and 15K respectively,which has excellent heat dissipation effect.The device has obvious advantages in high-power applications considering heat dissipation and power loss.