Nonvolatile semiconductor storage apparatus
US7505315B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 5, 2007 |
| Grant date | Mar 17, 2009 |
| Priority date | — |
| Expiry date | Sep 5, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/0483
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A nonvolatile semiconductor storage apparatus comprises a memory cell array having a plurality of memory cells which are connected to word lines and to bit lines and in each of which different information of x (x is an integer equal to or larger than 3) bits is stored in association with 2x threshold voltages, the x-bit information being able to be read from each memory cell by applying a read voltage to the corresponding word line; a row decoder connected to the word lines to supply voltages to the word lines to operate the memory cells; and a sense amplifier device connected to the bit lines to read data stored in the memory cells and to hold the read data and data written to the memory cells, wherein the x-bit information corresponding to a certain threshold voltage differs from that corresponding to the adjacent threshold voltage by only 1 bit, 2x−1 of the read voltages are each set for a pair of adjacent threshold voltages, and applying any of the read voltages to the word line determines the x-bit information stored in the memory cell, and at least two read voltages are set in order to determine information for each of the x bits.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.