Test for weak SRAM cells
US7200057B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 2004 |
| Grant date | Apr 3, 2007 |
| Priority date | — |
| Expiry date | Mar 10, 2024 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2029/5006
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for testing a static random access memory (SRAM) array for the presence of weak defects. A 0/1 ratio is first written to the memory array (step 100), following which the bit lines BL and BLB are pre-charged and equalized to a threshold detection voltage (step 102). The threshold detection voltage is programmed according to the 0/1 ratio of cells, so as to take into account specific cell criterion and/or characteristics. Next, the word lines associated with all of the cells in the array are enabled substantially simultaneously (step 104), the bit lines are then shorted together (step 106), the word lines are disabled (step 108) and the bit lines are released (step 110). Following these steps, the contents of the SRAM array are read and compared against the original 0/1 ratio (step 112). 10 Any cells whose contents do not match the original 0/1 ratio (i.e. those whose contents have flipped) are marked or otherwise identified as “weak” (step 114).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.