Semiconductor memory device having a large storage capacity and a high speed operation
US5677887A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Mar 10, 1995 |
| Grant date | Oct 14, 1997 |
| Priority date | — |
| Expiry date | Mar 10, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S257/904
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A semiconductor static memory device, which has an increased storage capacity without imposing an increased access time, includes first, second and third metallic layers. To begin, word lines for the transfer MOSFETS are formed of the same polysilicon layer used to form the gate electrodes of the transfer MOSFETs of the memory device. A metallic layer of the first layer is used for local word lines, with the polysilicon word lines and local word lines being connected at their ends or inside of cell arrays. A metallic layer of the second layer is used for bit layers, and a metallic layer of the third layer is used for main word lines. Consequently, the word lines have a decreased time constant, allowing fast memory access. Each of sense amplifiers used in the memory device are formed with MOSFETs, which are disposed divisionally in adjacent locations. Preferably the gate electrodes of the divided MOSFETs are located symmetrically. In this case, the offset voltage of the sense amplifiers decreases significantly.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.