| 摘要 |
PURPOSE:To acquire a semiconductor memory device which enables high integration without using a parasitic transistor by forming a storage node by a well using a single well-isolated MOS transistor as a memory cell. CONSTITUTION:A p-type well 2 is formed in each memory cell formation region of an n-type silicon substrate 1 through ion implantation of boron. A gate electrode 6 is formed in each p-type well 2 by a polycrystalline silicon film through a gate insulating film 5. Arsenic is ion-implanted using the gate electrode 6 as a mask to form an n-type source layer 7 and a drain layer 8. In the memory cell, the p-type well 2 which is formed for each MOS transistor is a storage node. Difference in threshold value voltage of a MOS transistor in accordance with difference in electric potential of the p-type well 2 in floating state is made to correspond to information '0', '1'. Write of information '1' is carried out by causing impact ionization near a drain and by charging the well 2 by a hole generated then. |
