Abstract: A semiconductor device having a novel structure is provided. The semiconductor device includes a CPU and an accelerator. The accelerator includes a first memory circuit and an arithmetic circuit. The first memory circuit includes a first transistor. The first transistor includes a semiconductor layer containing a metal oxide in a channel formation region. The arithmetic circuit includes a second transistor. The second transistor includes a semiconductor layer containing silicon in a channel formation region. The first transistor and the second transistor are provided to be stacked. The CPU includes a CPU core including a flip-flop provided with a backup circuit. The backup circuit includes a third transistor. The third transistor includes a semiconductor layer containing a metal oxide in a channel formation region.

Abstract: In a memory cell including a ferroelectric capacitor, data is read without data destruction. When the reading operation is performed in the memory cell including the ferroelectric capacitor, voltage applied to the counter electrode of the ferroelectric capacitor is gradually increased so as not to cause polarization destruction in the ferroelectric capacitor. A first reading operation from the memory cell is performed by applying a first voltage that does not cause polarization inversion of the ferroelectric layer to the capacitor, a second reading operation from the memory cell is performed by applying a second voltage that does not cause polarization inversion of the ferroelectric layer to the capacitor, and the second voltage is higher than the first voltage.

Abstract: A ferroelectric device including a metal oxide film having favorable ferroelectricity is provided. The ferroelectric device includes a first conductor, a metal oxide film over the first conductor, and a second conductor over the metal oxide film. The metal oxide film has ferroelectricity. The metal oxide film has a crystal structure. The crystal structure includes a first layer and a second layer. The first layer contains first oxygen and hafnium. The second layer contains second oxygen and zirconium. The hafnium and the zirconium are bonded to each other through the first oxygen. The second oxygen is bonded to the zirconium.

Abstract: A memory device which includes a gain-cell memory cell formed using an n-channel transistor and in which a potential lower than a potential applied to a bit line is not necessary is provided. Memory cells included in the memory device are arranged in a matrix, and each of the memory cells is connected to a write word line, a write bit line, a read word line, and a read bit line. The write word line is arranged in parallel to one of directions of a row and a column of memory cells arranged in a matrix, and the write bit line is arranged in parallel to the other of the directions of the row and the column. The read word line is arranged in parallel to the one of the directions of the row and the column of the memory cells arranged in a matrix, and the read bit line is arranged in parallel to the other of the directions of the row and the column.

Abstract: A memory device which includes a gain-cell memory cell formed using an n-channel transistor and in which a potential lower than a potential applied to a bit line is not necessary is provided. Memory cells included in the memory device are arranged in a matrix, and each of the memory cells is connected to a write word line, a write bit line, a read word line, and a read bit line. The write word line is arranged in parallel to one of directions of a row and a column of memory cells arranged in a matrix, and the write bit line is arranged in parallel to the other of the directions of the row and the column. The read word line is arranged in parallel to the one of the directions of the row and the column of the memory cells arranged in a matrix, and the read bit line is arranged in parallel to the other of the directions of the row and the column.

Abstract: A semiconductor device with a novel structure is provided. The semiconductor device includes a memory circuit including a first transistor and a second transistor. The first transistor is formed on a silicon substrate. The second transistor is formed in a layer above a layer where the first transistor is provided. The first transistor includes a first gate electrode and a first back gate electrode with a first channel formation region interposed therebetween. The first gate electrode is electrically connected to one of a source and a drain of the second transistor. The first back gate electrode is formed using a region where an impurity element imparting a conductivity type is selectively introduced in the silicon substrate. The second transistor includes a second channel formation region. The second channel formation region includes a metal oxide.

Abstract: A semiconductor device includes a CPU and an accelerator that includes a first memory circuit, a driver circuit, and a product-sum operation circuit. The first memory circuit includes a first data retention portion, a second data retention portion, and a data reading portion. The first data retention portion, the second data retention portion, and the data reading portion each include a first transistor. The first transistor contains a metal oxide in a channel formation region. First data stored in the first data retention portion and second data stored in the second data retention portion are each weight data input to the product-sum operation circuit. The product-sum operation circuit has a function of performing product-sum operation of the weight data and input data input through the driver circuit. The product-sum operation circuit and the driver circuit each include a second transistor. The second transistor contains silicon in a channel formation region.

Abstract: A semiconductor device having a novel structure is provided. The semiconductor device includes a CPU and an accelerator. The accelerator includes a first memory circuit and an arithmetic circuit. The first memory circuit includes a first transistor. The first transistor includes a semiconductor layer containing a metal oxide in a channel formation region. The arithmetic circuit includes a second transistor. The second transistor includes a semiconductor layer containing silicon in a channel formation region. The first transistor and the second transistor are provided to be stacked. The CPU includes a CPU core including a flip-flop provided with a backup circuit. The backup circuit includes a third transistor. The third transistor includes a semiconductor layer containing a metal oxide in a channel formation region.

Abstract: A memory device which includes a gain-cell memory cell formed using an n-channel transistor and in which a potential lower than a potential applied to a bit line is not necessary is provided. Memory cells included in the memory device are arranged in a matrix, and each of the memory cells is connected to a write word line, a write bit line, a read word line, and a read bit line. The write word line is arranged in parallel to one of directions of a row and a column of memory cells arranged in a matrix, and the write bit line is arranged in parallel to the other of the directions of the row and the column. The read word line is arranged in parallel to the one of the directions of the row and the column of the memory cells arranged in a matrix, and the read bit line is arranged in parallel to the other of the directions of the row and the column.

Abstract: A memory device which includes a gain-cell memory cell formed using an n-channel transistor and in which a potential lower than a potential applied to a bit line is not necessary is provided. Memory cells included in the memory device are arranged in a matrix, and each of the memory cells is connected to a write word line, a write bit line, a read word line, and a read bit line. The write word line is arranged in parallel to one of directions of a row and a column of memory cells arranged in a matrix, and the write bit line is arranged in parallel to the other of the directions of the row and the column. The read word line is arranged in parallel to the one of the directions of the row and the column of the memory cells arranged in a matrix, and the read bit line is arranged in parallel to the other of the directions of the row and the column.

Abstract: A memory device which includes a gain-cell memory cell formed using an n-channel transistor and in which a potential lower than a potential applied to a bit line is not necessary is provided. Memory cells included in the memory device are arranged in a matrix, and each of the memory cells is connected to a write word line, a write bit line, a read word line, and a read bit line. The write word line is arranged in parallel to one of directions of a row and a column of memory cells arranged in a matrix, and the write bit line is arranged in parallel to the other of the directions of the row and the column. The read word line is arranged in parallel to the one of the directions of the row and the column of the memory cells arranged in a matrix, and the read bit line is arranged in parallel to the other of the directions of the row and the column.

Abstract: A novel semiconductor device, a semiconductor device with low power consumption, or a semiconductor device capable of retaining data for a long period is provided. The semiconductor device includes a first selection circuit connected to a plurality of first memory circuits, a second selection circuit connected to a plurality of second memory circuits, and a third selection circuit connected to a plurality of third memory circuits, thereby being capable of conducting power gating of each of the first memory circuits, each of the second memory circuits, or each of the third memory circuits separately. Accordingly, the memory circuits to which data is not written or from which data is not read can be kept in a state where power supply thereto is stopped, so that power consumption of the semiconductor device can be reduced.

Abstract: A minute current measurement method is provided. In the current measurement method, a first potential is applied to a first terminal of a transistor under test, a second potential is applied to a first terminal of a first transistor, the first transistor is turned on to accumulate a predetermined charge in a node electrically connecting a second terminal of the transistor under test with a second terminal of the first transistor, a third potential of an output terminal of a read circuit electrically connected to the node is measured, the first transistor is turned off, a fourth potential of the output terminal of the read circuit electrically connected to the node is measured, the amount of the charge held by the node is estimated from the amount of change in the potential of the output terminal of the read circuit (e.g.

Abstract: A novel semiconductor device, a semiconductor device with low power consumption, or a semiconductor device capable of retaining data for a long period is provided. The semiconductor device includes a first selection circuit connected to a plurality of first memory circuits, a second selection circuit connected to a plurality of second memory circuits, and a third selection circuit connected to a plurality of third memory circuits, thereby being capable of conducting power gating of each of the first memory circuits, each of the second memory circuits, or each of the third memory circuits separately. Accordingly, the memory circuits to which data is not written or from which data is not read can be kept in a state where power supply thereto is stopped, so that power consumption of the semiconductor device can be reduced.

Abstract: A semiconductor device has a non-volatile memory cell including a write transistor which includes an oxide semiconductor and has small leakage current in an off state between a source and a drain, a read transistor including a semiconductor material different from that of the write transistor, and a capacitor. Data is written or rewritten to the memory cell by turning on the write transistor and applying a potential to a node where one of a source electrode and drain electrode of the write transistor, one electrode of the capacitor, and a gate electrode of the read transistor are electrically connected to one another, and then turning off the write transistor so that the predetermined amount of charge is held in the node.

Abstract: A minute current measurement method is provided. In the current measurement method, a first potential is applied to a first terminal of a transistor under test, a second potential is applied to a first terminal of a first transistor, the first transistor is turned on to accumulate a predetermined charge in a node electrically connecting a second terminal of the transistor under test with a second terminal of the first transistor, a third potential of an output terminal of a read circuit electrically connected to the node is measured, the first transistor is turned off, a fourth potential of the output terminal of the read circuit electrically connected to the node is measured, the amount of the charge held by the node is estimated from the amount of change in the potential of the output terminal of the read circuit (e.g.

Abstract: To provide a semiconductor device whose power can be turned off without the need for a peripheral circuit for data to escape temporarily and in which stored data is not lost even in an off state of the power of the device, and a memory device including the semiconductor device. In a holding circuit of the semiconductor device, a transistor that includes a semiconductor layer (at least a channel formation region) including an oxide semiconductor material with which small off-state current can be achieved is used. Further, the semiconductor device includes a switching element which enables a comparison circuit in which comparison between data stored in the holding circuit and reference data input from the outside does not need to be performed to become forcibly inactive.

Abstract: A semiconductor device has a non-volatile memory cell including a write transistor which includes an oxide semiconductor and has small leakage current in an off state between a source and a drain, a read transistor including a semiconductor material different from that of the write transistor, and a capacitor. Data is written or rewritten to the memory cell by turning on the write transistor and applying a potential to a node where one of a source electrode and drain electrode of the write transistor, one electrode of the capacitor, and a gate electrode of the read transistor are electrically connected to one another, and then turning off the write transistor so that the predetermined amount of charge is held in the node.

Abstract: A semiconductor device including a first transistor and a second transistor and a capacitor which are over the first transistor is provided. A semiconductor layer of the second transistor includes an offset region. In the second transistor provided with an offset region, the off-state current of the second transistor can be reduced. Thus, a semiconductor device which can hold data for a long time can be provided.

Abstract: A semiconductor device has a non-volatile memory cell including a write transistor which includes an oxide semiconductor and has small leakage current in an off state between a source and a drain, a read transistor including a semiconductor material different from that of the write transistor, and a capacitor. Data is written or rewritten to the memory cell by turning on the write transistor and applying a potential to a node where one of a source electrode and drain electrode of the write transistor, one electrode of the capacitor, and a gate electrode of the read transistor are electrically connected to one another, and then turning off the write transistor so that the predetermined amount of charge is held in the node.