| 摘要 |
PURPOSE:To increase the degree of freedom of a design by arranging elements constituting an RAM cell and an ROM cell and a layout and forming the RAM cell or the ROM cell only by varying a wiring with Al and the like. CONSTITUTION:P-type diffusion layers PP1-PP3 and N-type diffusion layers NN1-NN5 are shaped to a semiconductor substrate 1. These surfaces are coated with insulating films, an address line A0 and gate electrodes PS1, PS2 are formed by polycrystalline silicon, these surfaces are coated with insulating films, and contact holes H1-H6 are bored. When Al is evaporated and wirings Al1, Al2, a grounding conductor GND and a power line VDD are formed through selective etching, a memory cell corresponding to one bit of an RAM is acquired. When wirings Al3, Al4, a grounding conductor GND and a power line VDD are shaped by Al, a memory cell corresponding to two bits of an ROM is obtained. Accord ingly, the degree of freedom of a design is increased. |
