Research On Key Technology For High Voltage LDMOS Design

The high voltage power integrated circuits have widely used in the motor drive circuits, industryal control circuits, automotive electronics and switching power supply. The high voltage power devices design and high-low voltage compatible process also become hot topic to research at present. Because of the LDMOS (Lateral Double Diffused MOSFET) device, the source, the gate, the drain at the surface of chip, then the electrodes are located at the surface of device, so very easy to be integrated monolithically with other low voltage signal circuits through interconnects, and LDMOS commonly used in the high voltage power integrated circuits. In the integrated circuits, should the superior performance device,and LDMOS devices have advantages of large gain, high voltage, low distortion, So have widely applied in power integrated circuits, application range and have broad market prospects.High performance LDMOS devices have widely use, the breakdown voltage and on-resistance is the key when design, traditional LDMOS is hard to make the breakdown voltage and on-resistance to achieve the best matching requirements. In this article used software Tsuprem4set established LDMOS device structure, used software MEDICI simulation the device performance.The article, Mainly researched the key technology of LDMOS design, mainly included drift region analysis, RESURF technology analysis, field plate technology analysis and the temperature characteristic analysis of the device.(1) Drift region, Researched the drift region doping concentration, drift region length and thickness of the drift region, researched device characteristics. Set up different parameters of the device structure, researched device breakdown characteristic simulation,comparative analysis, and summarize the influence of these parameters about device.(2) The RESURF technology, According to the principle of RESURF technology to establish the reasonable structure device, researched RESURF technology structure of LDMOS devices, arounded when obtain the optimal device structure, its epitaxial layer impurity density of unit area (Ntot) is not a fixed value, researched the relationship between epitaxial layer impurity density of unit area and RESURF, to further optimize the device structure, and concluded a function between epitaxial layer impurity density of unit area and the concentration of the substrate.(3)Field plate technology, Researched the principle of field plate, and established the drain field plate for LDMOS, Researched the field plate device characteristics, analyzed the influence of different length of field plate the device. With field plate structure of LDMOS devices, can effectively restrain the.surface electric field, to prevent the device breakdown on the surface, to improve the breakdown voltage.(4)The temperature characteristics, According to the established device structure, to researched the temperature characteristics of the device.