Dual mode ferroelectric random access memory (FRAM) cell apparatus and methods with imprinted read-only (RO) data
US9401196B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 11, 2015 |
| Grant date | Jul 26, 2016 |
| Priority date | — |
| Expiry date | Jun 11, 2035 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C2211/4013
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Read-only (“RO”) data to be permanently imprinted in storage cells of a memory array are written to the memory array. One or more over-stress conditions such as heat, over-voltage, over-current and/or mechanical stress are then applied to the memory array or to individual storage cells within the memory array. The over-stress condition(s) act upon one or more state-determining elements of the storage cells to imprint the RO data. The over-stress condition permanently alters a value of a state-determining property of the state-determining element without incapacitating normal operation of the storage cell. The altered value of the state-determining property biases the cell according to the state of the RO data bit. The bias is detectable in the cell read-out signal. A pre-written ferroelectric random-access memory (“FRAM”) array is baked. Baking traps electric dipoles oriented in a direction corresponding to a state of the pre-written data and forms am RO data imprint.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.