| 摘要 |
PURPOSE:To prevent the discharge between the projection at the upper end of a polysilicon layer and the edge part of a source diffusion layer and suppress the leak current between a gate and a source by providing the upper end of the polysilicon layer for a gate electrode in the section lower than the surface of the source diffusion layer. CONSTITUTION:An epitaxial layer 12, a base layer 13, and a source diffusion layer 14 are formed in order on a semiconductor substrate 11, and then a trench 15, which reaches the interior of the epitaxial layer 12, piercing each diffusion layer 13 and 14, is formed by anisotropic etching. Next, a gate oxide film 16 is formed inside the trench 15, and then the first polysilicon layer 17 is stacked, and it is made into conductive by adding n-type impurities to this, and an oxide film 18 is formed by selectively removing the interior of the layer. Then, the second polysilicon layer 19 is stacked on an oxide film 18, and it is flattened, being etched back within the oxide layer 18, thus the second polysilicon layer 19 for stopping the trench is formed. Next, a gate electrode is formed by etching the oxide film 18 and the first polysilicon film 17. |
