| 摘要 |
PURPOSE:To lower impedance just under a memory on the writing of a memory cell by limitedly forming a second buried layer having concentration higher than that of a first buried layer just under the memory cell on the first buried layer. CONSTITUTION:A first N<+> type buried layer 2 is shaped onto a P-type semiconductor substrate 1, and second N<+> type buried layers 11 is formed. An N-type epitaxial layer 5 is grown, and two kinds of grooves 3, 4 for insulation isolation are cut and buried with an insulator. An N-type diffusion layer 6, a P-type diffusion layer 8 and an N-type diffusion layer 9 are shaped, and electrodes 10A, 10B are formed. Accordingly, the second buried layer 11 is constituted only just under a memory cell. |
