| 摘要 |
<p>A manufacturing method of a mask-ROM of two-layered gate electrode structure is provided. With this method, a cell transistor having a first-layered gate is converted into the depletion type according to data to be stored in the following manner. That is, a first conductive layer (32) is insulatively formed over a semi-conductor substrate (10) of a first conductivity type, a silicon nitride film (36) is formed on the first conductive layer (32), a polysilicon film (38) is formed on the silicon nitride film (36), the polysilicon film (38) is patterned and then altered into a silicon oxide film (46) so as to increase its volume, and the silicon nitride film (36) is patterned with the silicon oxide film (46) used as a mask to form windows (48) for permitting impurity to be doped therethrough. Then, impurity (54) for converting cell transistors into the depletion type according to data to be stored is doped from the windows (48) into the substrate (10) through the first conductive layer (32).</p> |
