SRAM cells with two P-well structure
US6677649B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 5, 2000 |
| Grant date | Jan 13, 2004 |
| Priority date | — |
| Expiry date | May 5, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S257/904
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Prior known static random access memory (SRAM) cells are required that a diffusion layer be bent into a key-like shape in order to make electrical contact with a substrate with a P-type well region formed therein, which would result in a decrease in asymmetry leading to occurrence of a problem as to the difficulty in micro-patterning. To avoid this problem, the P-type well region in which an inverter making up an SRAM cell is formed is subdivided into two portions, which are disposed on the opposite sides of an N-type well region NW1 and are formed so that a diffusion layer forming a transistor has no curvature while causing the layout direction to run in a direction parallel to well boundary lines and bit lines. At intermediate locations of an array, regions for use in supplying power to the substrate are formed in parallel to word lines in such a manner that one regions is provided per group of thirty two memory cell rows or sixty four cell rows.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.