| 摘要 |
PURPOSE:To prevent the disconnection from a word line by only etching the periphery of a recessed part a little by a method wherein a gate electrode is formed on sidewalls of the recessed part and in the periphery at an opening part of the recessed part. CONSTITUTION:A gate insulating film 28 is formed on the surface of a recessed part 24 and on the surface of a semiconductor substrate 21 surrounded by a LOCOS film 22. A gate electrode 29 is formed, via the gate insulating film 28, on sidewalls of the recessed part 24, in the periphery of the bottom adjacent to the sidewalls and in the periphery of an opening part of the recessed part 24. The gate electrode 29 is formed of a polysilicon film, and phosphorus is diffused to it. About the half of an element region 23 surrounded by the LOCOS film 22 is covered with the gate electrode 29; the electrode is extended in the upward and downward directions and forms a structure united to a word line. As a method to form the gate electrode 29, the recessed part 24 is first filled completely with polysilicon, and an etching-back operation is executed. In succession, the polysilicon is laminated again in the horizontal direction. After that, the outside of a region to be used as a guard is removed by an etching operation; then, the recessed part in the center is formed by an etching operation. Consequently, the electrode can be formed without a fear that it is disconnected from the word line. |
