| 摘要 |
<p>The dynamic mixed RAM/ROM memory is formed on the same semiconductor substrate and consists of a network of memory points arranged in rows and columns with address lines along the rows and read/write lines and polarisation lines along the columns. Each RAM memory point is a single MOS transistor with two levels of poly-Si. The source or drain is formed by a diffuse N+ zone of the substrate connected to a read/write line, while the other is formed by an inverse zone created by a band of poly-Si of the first level connected to a band of poly-Si having a polarisation potential (VDD). The inverse zone is thus w.r.t. the substrate and the first level poly-Si band, a storage capacitor for memorising binary information. The transistor grid is formed from a region of second level poly-Si connected to one of the address lines. The ROM memory points are defined by poly-Si at two levels which are those of the poly-Si of the RAM memory points. The ROM memory points forming part of a given column are all connected to an inverse zone created by a polarisation voltage line formed by the first level of poly-Si and connected by one end to the polarisation potential although at a uniform distance from the substrate such that each memory point presents a capacitive storage. Only the memory points affected by a given binary level (0) are provided with an MOS transistor (59) which connects, by its drain-source pathway, the storage capacity of this point to the respective read/write line.</p> |
