| 摘要 |
PURPOSE:To largely improve the integration degree by forming a plurality of memory cells in a recess by multi-dividing a polycrystalline Si as a capacitor formed in the recess. CONSTITUTION:An Si dioxide film 22 is removed by etching with a photo resist 23 as a mask, and the recess is provided on the surface of an Si substrate 21, thereafter the substrate 21 is covered with an Si dioxide film 24 by a thermal oxidation method, and further the polycrystalline Si 25, an Si dioxide film 26, and an Si nitride film 27 are successively formed. Afterwards, the entire surface except the capacitance isolation region in the recess is covered with a photo resist 28. Besides, a part of the films 26 and 27 of the isolation region and of the Si 25 are removed with the resist 28 as a mask. Next, when an Si dioxide film 29 is formed at the isolation region, the Si 25 is divided into two, and therefore the capacitance is divided into two. Only the accumulation capacitance can be increased without increasing the surface area by forming the Si 25 deeply in the substrate 21. |
