| 摘要 |
PURPOSE:To increase the value of storage capacity, augment reading voltage and obtain an MOSRAM resisting noises by a method wherein a junction area of an N layer or an inversion layer and a semiconductor substrate is increased. CONSTITUTION:An N type buried layer 7' is also formed on a P epitaxial layer 1b on a P type substrate 1a with an N type buried layer 12, and connected by an N layer 11. The layers 12, 7' each have corrugated uneven sections on junction surfaces with the layers 1a, 1b, and the layer 7' is a charge accumulation layer or an inversion layer. Storage capacity is made up by the MOS capacity of the poly Si3 of the first layer and the N layer 7' and junction capacity between the layer 7' and the layer 1b, between the layer 11 and the layer 1b, between the layer 12 and the layer 1b and between the layer 12 and the substrate 1a. Reading voltage is increased because a junction area of the N type inversion layer 7' and the N type buried layer 12 is wide and junction capacity is large. According to this constitution, the concentration of the substrate 1a can be augmented independently of the threshold voltage of an MOSFET and the capacity of a bit wire, and storage capacity can be increased. |
