Non-volatile semiconductor memory device
A non-volatile semiconductor device in which the number of redundant cells is not increased in proportion to the number of simultaneously accessed bits, having a redundant cell layout which prevents an increase in access time. This non-volatile semiconductor memory device has a regular cell array in which a plurality of memory cells are arranged. The regular cell array is divided into N sector regions in the row direction. Each of the N sector regions is divided into n first memory blocks in the row direction. One of the n first memory blocks is a redundant memory block. The (n−1) first memory blocks correspond to (n−1) input/output terminals.
1. A non-volatile semiconductor memory device comprising:
a regular cell array in which a plurality of memory cells are arranged in a column direction and a row direction, each of the memory cells having first and second non-volatile memory cells that are controlled by one word gate and first and second control gates, wherein:
the regular cell array is divided in the row direction into N sector regions;
each of the N sector regions is divided in the row direction into n first memory blocks; and
one of the n first memory blocks is a redundant memory block including a plurality of redundant memory cells.
2. The non-volatile semiconductor memory device as defined in claim 1 , further comprising:
n sense amplifiers provided corresponding to the n first memory blocks; and
a plurality of pass circuits each of which supplies a current which is output from one of the memory cells selected in each of the n first memory blocks to corresponding one of the n sense amplifiers.
3. The non-volatile semiconductor memory device as defined in claim 2 , further comprising:
(n−1) data output terminals; and
a multiplex circuit which selects (n−1) sense amplifier outputs from the n sense amplifiers, and then supplies the selected (n−1) sense amplifier outputs respectively to the (n−1) data output terminals.
4. The non-volatile semiconductor memory device as defined in claim 2 , further comprising:
a reference cell region including at least one reference memory cell which supplies a reference current to the n sense amplifiers.
5. The non-volatile semiconductor memory device as defined in claim 4 , wherein:
the reference cell region is divided in the row direction into n second memory blocks;
one of the n second memory blocks is a redundant memory block; and
the reference current is respectively supplied from the n second memory blocks to the n sense amplifiers.
6. The non-volatile semiconductor memory device as defined in claim 5 ,
wherein the number of the memory cells arranged in the row direction in the n first memory blocks is equal to the number of the memory cells arranged in the row direction in the n second memory blocks.
7. The non-volatile semiconductor memory device as defined in claim 6 , wherein:
each of the N sector regions is divided in the column direction into M large blocks, each of the M large blocks being divided in the column direction into m small blocks; and
the number of the memory cells arranged in the column direction in each of the n second memory blocks is smaller than the number of the memory cells arranged in the column direction in each of the m small blocks.
8. The non-volatile semiconductor memory device as defined in claim 6 ,
wherein lower order addressed in row and column addresses used in the cell selection in the regular cell array is used in the cell selection in the reference cell region when data is read.
9. The non-volatile semiconductor memory device as defined in claim 1 , wherein:
each of the n first memory blocks includes four bit lines extending in the column direction; and
the number of the memory cells arranged in the row direction in each of the n first memory blocks is four.
10. The non-volatile semiconductor memory device as defined in claim 1 , further comprising:
a control gate driver section which drives the first and second control gates of each of the memory cells in the regular cell array,
wherein the control gate driver section includes N local control gate drivers provided corresponding to the N sector regions, each of the N local control gate drivers setting potentials of the first and second control gates in corresponding one of the sector regions independent of other sector regions.
11. The non-volatile semiconductor memory device as defined in claim 10 ,
wherein when data is erased, one of the N local control gate drivers is selected to supply an erase potential to the first and second control gates in corresponding one of the N sector regions, data being erased in units of each of the sector regions.
12. The non-volatile semiconductor memory device as defined in claim 1 ,
wherein each of the first and second non-volatile memory cells has an ONO film formed of an oxide film (O), a nitride film (N), and an oxide film (O) as a charge trap site.