| 摘要 |
PURPOSE:To reduce the occurrence of interference noise and parasitic capacities related to a bit line so as to secure stable operations by forming memory cells on one surface of a semiconductor layer and the bit line on the other surface. CONSTITUTION:Since a bit line 24 is formed on one surface of a Si substrate 11, with a transistor 12 and capacity element 13 being provided on the other surface, the distance (d) between metallic wiring 25 and substrate 11 is small. In addition, since a thick SiO2 film 32 exists between the bit line 24 and substrate 11, the interference noise and parasitic capacity between the bit line 24 and substrate 11 are also small. Trenches 32 are deep due to the thick SiO2 film 31, etc. However, since the electric current flowing through the bit line 24 is small from the first, a polycrystalline Si film 33 has a better coverage than the metallic wiring 25 has and since the film 33 contains phosphor, the Si film 33 is low in resistance. Therefore, the deep trenches 32 do not cause any trouble. |
