Semiconductor memory device
US4942556A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 10, 1989 |
| Grant date | Jul 17, 1990 |
| Priority date | — |
| Expiry date | Jul 10, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C29/44
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a defect relieving technology which replaces defective memory cells of a semiconductor memory device by spare memory cells, use is made of an associative memory. Address information of a defective memory cell is stored as a reference data of the associative memory, and new address information of a spare memory cell is written down as output data of the associative memory. A variety of improvements are made to the associative memory. For instance, a plurality of coincidence detection signal lines of the associative memory are divided into at least two groups, and one group among them is selected by switching means. Reference data of the associative memory comprises three values consisting of binary information of "0" and "1", and don't care value "X". The associative memory further includes a plurality of electrically programable non-volatile semiconductor memory elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.