| Patent application number | Description | Published |
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| 20110255325 | SEMICONDUCTOR DEVICE - An object is to provide a semiconductor device having a novel structure, which can hold stored data even when not powered and which has an unlimited number of write cycles. A semiconductor device includes a memory cell including a widegap semiconductor, for example, an oxide semiconductor. The memory cell includes a writing transistor, a reading transistor, and a selecting transistor. Using a widegap semiconductor, a semiconductor device capable of sufficiently reducing the off-state current of a transistor included in a memory cell and holding data for a long time can be provided. | 10-20-2011 |
| 20110280061 | SEMICONDUCTOR DEVICE - A semiconductor device includes a plurality of memory cells including a first transistor and a second transistor, a reading circuit including an amplifier circuit and a switch element, and a refresh control circuit. A first channel formation region and a second channel formation region contain different materials as their respective main components. A first gate electrode is electrically connected to one of a second source electrode and a second drain electrode. The other of the second source electrode and the second drain electrode is electrically connected to one of input terminals of the amplifier circuit. An output terminal of the amplifier circuit is connected to the other of the second source electrode and the second drain electrode through the switch element. The refresh control circuit is configured to control whether the switch element is turned on or off. | 11-17-2011 |
| 20120012845 | SEMICONDUCTOR DEVICE - A semiconductor device with a novel structure is provided, which can hold stored data even when no power is supplied and which has no limitations on the number of writing operations. A semiconductor device is formed using a material which enables off-state current of a transistor to be reduced significantly; e.g., an oxide semiconductor material which is a wide-gap semiconductor. With use of a semiconductor material which enables off-state current of a transistor to be reduced significantly, the semiconductor device can hold data for a long period. In a semiconductor device with a memory cell array, parasitic capacitances generated in the nodes of the first to the m-th memory cells connected in series are substantially equal, whereby the semiconductor device can operate stably. | 01-19-2012 |
| 20120014157 | SEMICONDUCTOR DEVICE - A plurality of memory cells included in a memory cell array are divided into a plurality of blocks every plural rows. A common bit line is electrically connected to the divided bit lines through selection transistors in the blocks. One of the memory cells includes a first transistor, a second transistor, and a capacitor. The first transistor includes a first channel formation region. The second transistor includes a second channel formation region. The first channel formation region includes a semiconductor material different from the semiconductor material of the second channel formation region. | 01-19-2012 |
| 20120033484 | SEMICONDUCTOR DEVICE AND DRIVING METHOD THEREOF - The semiconductor device is formed using a material which allows a sufficient reduction in off-state current of a transistor; for example, an oxide semiconductor material, which is a wide gap semiconductor, is used. When a semiconductor material which allows a sufficient reduction in off-state current of a transistor is used, the semiconductor device can hold data for a long period. In addition, the timing of potential change in a signal line is delayed relative to the timing of potential change in a write word line. This makes it possible to prevent a data writing error. | 02-09-2012 |
| 20120033485 | SEMICONDUCTOR DEVICE - In a semiconductor device which includes a bit line, m (m is a natural number of 3 or more) word lines, a source line, m signal lines, first to m-th memory cells, and a driver circuit, the memory cell includes a first transistor and a second transistor for storing electrical charge accumulated in a capacitor, and the second transistor includes a channel formed in an oxide semiconductor layer. In the semiconductor device, the driver circuit generates a signal to be output to a (j−1)th (j is a natural number of 3 or more) signal line with the use of a signal to be output to a j-th signal line. | 02-09-2012 |
| 20120033486 | SEMICONDUCTOR DEVICE AND METHOD FOR DRIVING SEMICONDUCTOR DEVICE - It is an object to provide a semiconductor device with a novel structure in which stored data can be held even when power is not supplied, and does not have a limitation on the number of writing operations. A semiconductor device includes a plurality of memory cells each including a transistor including a first semiconductor material, a transistor including a second semiconductor material that is different from the first semiconductor material, and a capacitor, and a potential switching circuit having a function of supplying a power supply potential to a source line in a writing period. Thus, power consumption of the semiconductor device can be sufficiently suppressed. | 02-09-2012 |
| 20120033487 | SEMICONDUCTOR DEVICE AND DRIVING METHOD THEREOF - A semiconductor device including a nonvolatile memory cell in which a writing transistor which includes an oxide semiconductor, a reading transistor which includes a semiconductor material different from that of the writing transistor, and a capacitor are included is provided. Data is written to the memory cell by turning on the writing transistor and applying a potential to a node where a source electrode (or a drain electrode) of the writing transistor, one electrode of the capacitor, and a gate electrode of the reading transistor are electrically connected, and then turning off the writing transistor, so that the predetermined amount of charge is held in the node. Further, when a p-channel transistor is used as the reading transistor, a reading potential is a positive potential. | 02-09-2012 |
| 20120033510 | SEMICONDUCTOR DEVICE - An object is to provide a semiconductor device with a novel structure, which can hold stored data even when power is not supplied and which has an unlimited number of write cycles. The semiconductor device is formed using a memory cell including a wide band gap semiconductor such as an oxide semiconductor. The semiconductor device includes a potential change circuit having a function of outputting a potential lower than a reference potential for reading data from the memory cell. When the wide band gap semiconductor which allows a sufficient reduction in of state current of a transistor included in the memory cell is used, a semiconductor device which can hold data for a long period can be provided. | 02-09-2012 |
