Design Of Split-gate DMOS With Critical Dimension Of 0.13?m

The Split-gate DMOS is a kind of trench MOSFET structure,adopting the principle of charge balance,which can improve the epitaxial layer doping concentration to reduce the conduction resistance Ron,sp.It's shield-gate can make the Cgd/Ciss ratio reduced to improving the ability of dv/dt of the device.The Split-gate DMOS also has a great FOM(RDS*Qg)value,especially in the field of low voltage power MOSFET.As the representative of the semiconductor companies abroad,Infineon and Fairchild has developed the mature split-gate DMOS process line and generations of the split-gate DMOS products,which have surpass the domestic both in product features and technology level.The domestic products still have certain gaps when compared with similar foreign products.Therefore,it has a great significance of researching independently based on the 0.13 ?m process of the split-gate DMOS to enrich domestic low pressure DMOS with high performance.The structure simulation of split-gate DMOS is carried out by using the electric parameter simulation software MEDICI according to the requirements.Some important parameters,such as cell size,cell concentration,and the length of shielding grid were optimized based on the basic theory of split-gate DMOS.The optimization of the cell voltage BV=59.7V,the specific on resistance Ron,sp=3.3×10-4?·cm2,threshold voltage Vth= 2.8V,gate drain capacitance Cgd=1.22×10-3 pF/?m2.Finally,compared the split-gate DMOS with U-MOSFET and CC-MOSFET with similar structure parameters about the mian electrical parameters,and make a summary of the advantage of the split-gate DMOS designed.The split-gate DMOS has also designed in process manufacturing based on the 0.13?m production line and the simulation of the device structure,by using the electric parameter simulation software TSUPREM4.The paper especially introduced the fabrication method of the shield gate and a control gate,optimized important parameters such as the implant dose,implant time on pbody,and designed an optimization terminal structure based on process steps.The split-gate structure after the process optimization has the cell voltage BV=66.3V,the specific on resistance Ron,sp=3.3×10-4?·cm2,threshold voltage Vth= 3.1V,gate drain capacitance Cgd=1.29×10-3 pF/?m2,and terminal withstand voltage=63.4V.In the end,an improved split-gate DMOS structure has been proposed which can optimize the capacitance parameters of the cell under the condition of the same breakdown voltage,and the resistance does not increased obviously.The simulation results indicated that the design of split-gate DMOS based on 0.13?m technology is reasonable and the electrical parameters of the device meet the design requirements.