| 摘要 |
PURPOSE:To prevent soft errors and to sufficiently increase a storage capacity of a memory capacitor by burying trenches having different depths with an insulating film, adhering a second Si substrate, then forming a special MOSFET and capacitors to form an SOI structure. CONSTITUTION:A first trench 73 is formed in a first silicon semiconductor substrate 71, a second trench 74 shallower then the trench 73 is then formed, and then trenches 73, 74 are filled with an insulating film 76. Then, after a second silicon semiconductor substrate 77 is adhered to the substrate 71, and the substrate 71 is reduced in thickness to expose the bottom of the trench 73. Thereafter, a MOS field effect transistor having a drain region 82 adjacent to the trench 73 and a source region 81 opposed to the trench 74 is formed. Subsequently, a cell plate 84 opposed to the region 82 is formed on the substrate 71 through an insulating film 83. |
