Semiconductor device and method for driving semiconductor device
First Claim
1. A semiconductor device comprising:
- a memory cell comprising a first transistor including an oxide semiconductor and a second transistor including a material other than the oxide semiconductor;
a driver circuit configured to drive the memory cell; and
a potential generating circuit configured to generate potentials supplied to the driver circuit,wherein the driver circuit comprises;
a data buffer configured to hold a first data to be written into the memory cell;
a writing circuit configured to write a second data with one potential of the potentials into the memory cell in accordance with the first data;
a reading circuit configured to read the second data written into the memory cell; and
a verifying circuit configured to verify whether the second data agrees with the first data or not,wherein the one potential is a write potential for the memory cell where the second data agrees with the first data, andwherein the write potential is changed to another potential of the potentials, for the memory cell where the second data does not agree with the first data.
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Accused Products
Abstract
A semiconductor device with a novel structure is provided, in which the operation voltage is reduced or the storage capacity is increased by reducing variation in the threshold voltages of memory cells after writing. The semiconductor device includes a plurality of memory cells each including a transistor including an oxide semiconductor and a transistor including a material other than an oxide semiconductor, a driver circuit that drives the plurality of memory cells, and a potential generating circuit that generates a plurality of potentials supplied to the driver circuit. The driver circuit includes a data buffer, a writing circuit that writes one potential of the plurality of potentials into each of the plurality of memory cells as data, a reading circuit that reads the data written into the memory cells, and a verifying circuit that verifies whether the read data agrees with data held in the data buffer or not.
142 Citations
28 Claims
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1. A semiconductor device comprising:
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a memory cell comprising a first transistor including an oxide semiconductor and a second transistor including a material other than the oxide semiconductor; a driver circuit configured to drive the memory cell; and a potential generating circuit configured to generate potentials supplied to the driver circuit, wherein the driver circuit comprises; a data buffer configured to hold a first data to be written into the memory cell; a writing circuit configured to write a second data with one potential of the potentials into the memory cell in accordance with the first data; a reading circuit configured to read the second data written into the memory cell; and a verifying circuit configured to verify whether the second data agrees with the first data or not, wherein the one potential is a write potential for the memory cell where the second data agrees with the first data, and wherein the write potential is changed to another potential of the potentials, for the memory cell where the second data does not agree with the first data. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor device comprising:
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memory cells each comprising a first transistor including an oxide semiconductor and a second transistor including a material other than the oxide semiconductor; a driver circuit configured to drive the memory cells; and a potential generating circuit configured to generate potentials supplied to the driver circuit, wherein the driver circuit comprises; a data buffer configured to hold a first data to be written into the memory cells; a writing circuit configured to write a second data with one potential of the potentials into the memory cells in accordance with the first data; a reading circuit configured to read the second data written into the memory cells; and a verifying circuit configured to verify whether the second data agrees with the first data or not, wherein the one potential is a write potential for a part of the memory cells where the second data agree with the first data; and wherein the write potential is changed to another potential of the potentials, for the others of the memory cells where the second data does not agree with the first data. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method for driving a semiconductor device comprising a memory cell comprising a first transistor including an oxide semiconductor and a second transistor including a material other than the oxide semiconductor, the method comprising the steps of:
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holding a first data to be written into the memory cell in a data buffer; writing a second data with one potential of potentials into the memory cell in accordance with the first data; reading the second data written into the memory cell; verifying whether the second data agrees with the first data or not; and determining the one potential as a first write potential for the memory cell where the second data agrees with the first data, or changing the first write potential to another potential of the potentials, for the memory cell where the second data does not agree with the first data. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A method for driving a semiconductor device comprising memory cells each comprising a first transistor including an oxide semiconductor and a second transistor including a material other than the oxide semiconductor, the method comprising the steps of:
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holding a first data to be written into the memory cells in a data buffer; writing a second data with one potential of potentials into the memory cells in accordance with the first data; reading the second data written into the memory cells; verifying whether the second data agrees with the first data or not; determining the one potential as a first write potential for a first part of the memory cells where the second data agrees with the first data; and changing the first write potential to another potential of the potentials, for a second part of the memory cells where the second data does not agree with the first data. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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Specification