| 摘要 |
PURPOSE:To prevent a stepwise difference and a bowling from occurring in a trench by employing a mask having a window of the shape sequentially expanding outside from the surface of a mask toward the surface of a semiconductor substrate in an area of a window parallel to the surface of the substrate. CONSTITUTION:The inner wall of a window is dry etched under etching conditions of strong directivity to a semiconductor substrate 31 from above a reversely tapered mask pattern 41. Even when the mask layer 41 is etched and deformed, edge portions 39a always cover the exposed surface of the substrate in an overhanging state. Thus, the inner wall of the window 39 of the layer 41 remains reversely tapered shape. In this manner, since the inner wall of the window 39 is less directly contacted with etching ions, the abrupt film reduction of the layer 41 does not occur in a direction parallel to the surface of the substrate to eliminate a stepwise difference and a bowling on the inner wall of a trench to obtain a tapered trench 45.
|
