| 摘要 |
PURPOSE:To obtain a mask ROM having a large memory capacity for a unit area by a method wherein a conductor layer connected to a conductor layer is formed in a field region under a gate electrode corresponding to information to be stored. CONSTITUTION:A memory cell field region surrounded by a field oxide film 2 is formed on a P-type Si substrate 1 and a polycrystalline Si electrode 4 is formed on the field region with a gate oxide film 3 between. An N-type conductor region 5 is formed in the field region exposed from the electrode 4. A conductor layer 6 is formed also in the field region (gate region) beneath the electrode 4 by N-type impurity diffusion. A gate capacitor is composed of the electrode 4, the conductor layer 6 and the gate oxide film 3. If information is programmed with this constitution, a source region which is necessary in a conventional MOS memory cell can be eliminated, so that a mask ROM having a larger memory capacity corresponding to the eliminated source region can be formed. |
