The Development Of High Performance And Low Cost Low Voltage Trench Double Diffused Mosfet

Stepping into the 21st century, the famous Moore's Law drives the industry of semiconductor into an exhibition period. Various high performance chips are widely used in people's lives. A huge market share has been occupied by power devices. In this special area, the power devices are mainly sorted by discrete devices and power integrated circuits, respectively.In this dissertation, Trench Double-diffused Metal-Oxide-Semiconductor Field-Effect-Transistor is presented, which is one of the most popular discrete devices applied in the low power application area. After studying the domestic and foreign research results, a method of assessing the merit and demerit of Trench DMOSFET by adjusting the figure of merit Ro n×Qgd has been introduced. Considering cost and design requirement, in order to achieve smaller Ro n, the approach of scaling down the pitch size to 1.4μm is provided finally. Meanwhile, the high risk of punch-through due to process limitation is described when channel length became smaller and source junction became shallower. The parasitic NPN bipolar effect will be induced by source photo resist lifting and source dose implanting to unexpected active area. Then the solution of using the poly stickup structure and trench contact technology without any extra mask and extra process steps are demonstrated. An optimized process window is found by simulation and wafer experiments. After comparing the final electric characteristics with original datasheet, the results are positive and acceptable. The low-voltage power trench DMOSFET has been successfully proven to get the highly stable performance and low specific-on-resistance finally.