Read-only memory and corresponding method of manufacturing by MOS technology

摘要

In a method for the manufacture of cells of a read-only memory, each cell comprises a MOS transistor formed by a first diffusion and a second diffusion of impurities of a first type in a semiconductor substrate with impurities of a second type. These two diffusions are separated by a channel surmounted by a gate. A thick oxide zone is made in the zone designed for the first diffusion, so that the making of the diffusions leads to a first diffusion in two parts separated by this thick oxide zone, a first part adjoining the channel and a second part on the periphery of the transistor. A particular encoding step makes it possible, by means of a mask, to eliminate the thick oxide in certain cells so that these encoded cells have a first continuous diffusion.