Semiconductor device and its control method
View Patent ↗A semiconductor device includes sectors having memory cells connected to local word lines, decoders selecting the sectors, and a circuit generating, in erasing of a selected sector, a control signal that causes a corresponding one of the decoders associated with the selected sector to be temporarily unselected. Each of the sectors includes a pull-up transistor that is driven by a corresponding one of the decoders via a corresponding one of global word lines connecting the sectors and drives one of the local word lines, and the pull-up transistor is kept OFF by the control signal.
1. A semiconductor device comprising:
sectors comprising memory cells connected to local word lines;
decoders selecting the sectors via global word lines;
a dummy line; and
a first circuit coupling the dummy line with the global word lines at the time of discharging the local word lines after erasing using a negative voltage applied to the local word lines.
2. The semiconductor device as claimed in claim 1 , further comprising a bias circuit biasing a given voltage to the dummy line in reading and programming.
3. The semiconductor device as claimed in claim 1 , further comprising a second circuit generating, while erasing a selected sector, a first control signal that causes a corresponding one of the decoders associated with the selected sector to be temporarily unselected.
4. The semiconductor device as claimed in claim 1 , further comprising a third circuit generating, while programming a selected sector, a plurality of second control signals that cause the local word lines of unselected sectors to be in a floating state.
5. A method of controlling a semiconductor device comprising the steps of:
selecting one of a plurality of sectors comprising memory cells connected to local word lines; and
coupling a dummy line with a global word line at the time of discharging the local word lines after erasing using a negative voltage applied to the local word lines.
6. The method as claimed in claim 5 , further comprising:
generating a first control signal, while erasing a selected sector, that causes a corresponding decoder associated with the selected sector to be temporarily unselected.
7. The method as claimed in claim 5 , further comprising:
generating a plurality of second control signals, while programming a selected sector, that cause the local word lines of unselected sectors to be in a floating state.
8. The semiconductor device as claimed in claim 4 , wherein:
each of the sectors comprises a pull-up transistor and a pull-down transistor for driving one of the local word lines, both transistors being driven by a corresponding one of the decoders; and
the plurality of second control signals turning off the pull-up and pull-down transistors in the unselected sectors in programming.
9. The semiconductor device as claimed in claim 4 , wherein the unselected local word lines in the selected sector are set to ground.
10. The method as claimed in claim 7 , wherein the unselected local word lines in the selected sector are set to ground.
11. The method of controlling a semiconductor device as claimed in claim 7 , wherein each of the sectors comprises a pull-up transistor and a pull-down transistor for driving one of the local word lines, both transistors being driven by the corresponding decoder associated with the selected sector; and
the plurality of second control signals turning off the pull-up and pull-down transistors in the unselected sectors in programming.