Research On Trench-gate 2D-pseudo-super Junction LDMOS

The basic structure of Lateral Double-diffused Metal Oxide Semiconductor Field Effect Transistor(LDMOS)is introduced.The breakdown voltage?on-state performance?advantage and application of it are briefly analyzed.At the same time,the technologies for optimizing drift region are discussed and summarized in detail,especially for Reduced SURface Field(RESURF)?super-junction technology and trench structure.From the point of device structure,three new two dimensional(2D)pseudo-super-junction LDMOS structures are proposed.The devices are studied and the key parameters are optimized by simulating,as a result,high breakdown voltage and low specific on-resistance are achieved simultaneously.Trench-Gate 2D pseudo-super-junction LDMOS: Alternate doping P/N pillars are applied in the trench-gate LDMOS,and heavily doped N+ region in drain is extended to N-drift.When device is in a state of reverse voltage,P-pillar and N-pillar is in low potential and high potential respectively,so that drift region can deplete fully.I-V characteristic and voltage properties are analyzed based on the physical knowledge of power device and simulation of MEDICI.Finally,breakdown voltage of 500 V are achieved which improved by 32.6% compared with conventional LDMOS,and specific on-resistance decreased by 62.5%.Trench-Gate 2D pseudo-super-junction LDMOS with Step-doping P-pillar: Based on the conventional structure,technology of changing concentration is applied to optimize the drift region.Technology of lateral variable doping is applied to design P-pillar,and doping concentration becoming lower from source to drain.On the one hand,new electric field generates at the interface of junction P1/P2 and junction P2/P3;On the other hand,charge imbalance caused by substrate-assisted-depletion effect is eased.Finally,breakdown voltage of 814 V and specific on-resistance of 0.19? ·cm2 are achieved simultaneously.2D pseudo-super-junction LDMOS with trench drift region: Based on the conventional structure,technology of changing drift region shape is applied to optimize the drift region.Oxide trenches are introduced to drift region to fold it.On the one hand,drift region becomes longer due to the folded drift region;On the other hand,specific on-resistance is decreased due to the shorter measure of device.Same level of Breakdown Voltage can be achieved in 35?m drift region while conventional structure in 50?m drift region.