Non-volatile flash memory having a specific difference between source/floating gate and drain/floating gate overlapped portions
View Patent ↗A structure of a non-volatile flash memory, in which a punch-through current is suppressed and the area of a memory cell is reduced, is provided. The non-volatile flash memory being a NOR type non-volatile flash memory provides floating gates and a common source line, and drains. And at the structure of the non-volatile flash memory, a region overlapped one of the drains and one of the floating gates in a memory cell is larger than a region overlapped the common source and one of the floating gates in the memory cell.
1. A structure of a non-volatile flash memory that is a NOR type non-volatile flash memory, which provides floating gates and a common source line, wherein:
the difference (a−b) between a region “a” overlapped one of drains and one of said floating gates in a memory cell, and a region “b” overlapped a source and one of said floating gates in said memory cell is 0.02 μm or more.
2. A structure of a non-volatile flash memory that is a NOR type non-volatile flash memory, which provides floating gates and a common source line in accordance with claim 1 , wherein:
said source is composed of first sources and a second source, and said first sources and said second source are formed in a state that said first and second sources are contacted with one another, and said first sources are formed at regions overlapped with said floating gates.
3. A structure of a non-volatile flash memory that is a NOR type non-volatile flash memory, which provides floating gates and common source line in accordance with claim 2 , wherein:
the impurity concentration of said second source is higher than that of said first sources.
4. A structure of a non-volatile flash memory that is a NOR type non-volatile flash memory, which provides floating gates and a common source line in accordance with claim 2 , wherein:
said source composed of said first and second sources is formed in a state that said first and second sources are unified.
5. The structure of claim 1 , wherein “a” is more that 0.03 μm and “b” is less than 0.01 μm.
6. The structure of claim 1 , wherein (a−b) is more that 0.05 μm.