The Design And Research Of Novel Trench LDMOS Structure

Lateral power device is considered as the core device in the power integrated circuit.The research of lateral high-voltage power devices is mainly focused on achieving high voltage,low power consumption,and miniaturization of power device.Although the long length and low concentration of drift region can achieve high breakdown voltage,it can also increase the specific on-resistance simultaneously.And this phenomenon is called 2.5 power "silicon limit"problem which exists between specific on-resistance and breakdown voltage.Modulation of two-dimensional fields,which is based on the concept of the self-adapted balance of charge,is an effective method to improve breakdown voltage for device.Aiming at optimizing the characteristics of breakdown voltage and specific on-resistance,The dissertation proposed two new structures on the basis of two different balance mechanisms that occur distinctively in the induced charge and polarization charge.one of the two structures is SOI trench lateral power device,the other is bulk silicon trench lateral power device.The paper has finished donumerical simulation and mechanism research by the TCAD tools,designed process preparation and layout designation of new structures.(1)The BDT SOI TLDMOS(Body Depletion Terminal SOI Trench LDMOS)structure has been proposed.The features of device is that there are vertical body depletion terminal in the oxide trench of drift region and highly doped N pillar.According to the self-adaptive balance mechanism of inductive charge,the inductive charge induced by body depletion plate and the ionization charge in the drift region meet the self-adaptive balance requirement when the device is in the off-state,which reshape the distribution of the electric field,enhance the dialect trench electric field,assist depleting drift region and improve the concentration of drift region.In the on-state,the highly doped N pillar can provide low resistance current channel to realize the drop of specific on-resistance.The simulation results in Medici showed that the BV is 668V,the Ron,sp is 44.7m?·cm2,and The FOM is 9.98MW·cm-2,respectively.Compared with traditional trench SOI LDMOS with the same cell pitch,The BV is increased by 43%,Ron,sp is reduced by 83.1%.(2)The HKLR LDMOS(high-K Low Specific on-Resistance LDMOS)structure has been proposed.The structure has three characteristics.There are high K dialect trench,thin highly doped N pillar and a trench gate.According to the self-adaptive balance mechanism of polarization charge,the polarization charge bounded by high K dialect trench and the ionization charge in the drift region meet the self-adaptive balance requirement when the device is in the off-state,which optimize the distribution of the electric field,enhance the bulk electric field,assist depleting drift region,and improve the concentration of drift region.In the on-state,the highly doped N pillar provide a low resistance current channel so that can reduce specific on-resistance.And the trench gate can form MIS capacitance structure both in the drift region and trench gate oxide layer to assist depleting drift region and to provide low resistance current channel.The simulation results in Medici showed that the BV is 534V,the Ron,sp is 70.6m?·cm2,and the FOM is 4.039MW cm-2,respectively.Compared with the same cell pitch of traditional structure,BV is increased by 19.5%,Ron,sp is reduced by 53.4%.(3)On the premise of process technical conditions which are already exited,the dissertation designed two different complete sets of process preparation scheme for the two new structures respectively.At the end of the dissertation,the layout design of new structure is finished according to the rule of layout design.