A floating memristor with a nano-battery between a top and bottom floating gates is disclosed. The floating memristor includes a nano-battery, a top floating gate assembly disposed on an anode of the nano-battery, and a bottom floating gate assembly disposed on a cathode of the nano-battery. The floating memristor is an artificial synapse. The top floating gate assembly and the anode of the nano-battery convert electric signal to ionic signal by tunneling effect and field effect to simulate a presynaptic membrane. The electrolyte of the nano-battery is an ionic channel as a synaptic gap. The anode and the bottom floating gate transfer the ionic signal to electric signal by field effect and tunneling effect to simulate a postsynaptic membrane.

A semiconductor memory device includes a semiconductor member extending in a first direction, a first interconnect extending in a second direction crossing the first direction, and a first electrode disposed between the semiconductor member and the first interconnect. A curvature radius of a corner portion facing the semiconductor member in the first electrode is larger than a curvature radius of a corner portion facing the first interconnect in the first electrode.

An object is to provide a semiconductor device having a novel structure with a high degree of integration. A semiconductor device includes a semiconductor layer having a channel formation region, a source electrode and a drain electrode electrically connected to the channel formation region, a gate electrode overlapping with the channel formation region, and a gate insulating layer between the channel formation region and the gate electrode. A portion of a side surface of the semiconductor layer having the channel formation region and a portion of a side surface of the source electrode or the drain electrode are substantially aligned with each other when seen from a planar direction.

The degree of integration of a semiconductor device is enhanced and the storage capacity per unit area is increased. The semiconductor device includes a first transistor provided in a semiconductor substrate and a second transistor provided over the first transistor. In addition, an upper portion of a semiconductor layer of the second transistor is in contact with a wiring, and a lower portion thereof is in contact with a gate electrode of the first transistor. With such a structure, the wiring and the gate electrode of the first transistor can serve as a source electrode and a drain electrode of the second transistor, respectively. Accordingly, the area occupied by the semiconductor device can be reduced.

A semiconductor device is described, which includes a first transistor, a second transistor, and a capacitor. The second transistor and the capacitor are provided over the first transistor so as to overlap with a gate of the first transistor. A semiconductor layer of the second transistor and a dielectric layer of the capacitor are directly connected to the gate of the first transistor. The second transistor is a vertical transistor, where its channel direction is perpendicular to an upper surface of a semiconductor layer of the first transistor.

A thin film transistor is deposited over a portion of a metal layer over a substrate. A memory element is coupled to the thin film transistor to provide a first memory cell. A second memory cell is over the first memory. A logic block is coupled to at least the first memory cell.

A low-power-consuming semiconductor device that can store analog data stably and very accurately is provided at low cost. The semiconductor device includes a power supply portion, a sensor portion, and a memory element portion. The sensor portion acquires analog data. The memory element portion stores the analog data. A channel formation region of a transistor included in the memory element portion is formed in an oxide semiconductor film. The semiconductor device does not include an analog/digital converter circuit and has functions of measuring and storing analog data.

Provided is a highly integrated semiconductor device, a semiconductor device with large storage capacity with respect to an area occupied by a capacitor, a semiconductor device capable of high-speed writing, a semiconductor device capable of high-speed reading, a semiconductor device with low power consumption, or a highly reliable semiconductor device. The semiconductor device includes a first transistor, a second transistor, and a capacitor. A conductor penetrates and connects the first transistor, the capacitor, and the second transistor. An insulator is provided on a side surface of the conductor that penetrates the capacitor.

A memory device which stores a large amount of data is provided. The memory device includes a first transistor, a second transistor, a third transistor, a first capacitor, a second capacitor, and first to third wirings. The first transistor includes an oxide semiconductor in a channel formation region, the second transistor includes silicon in a channel formation region, and the third transistor includes silicon in a channel formation region. The first capacitor is provided in the same layer as the first transistor. A region of the second capacitor and a region of the first capacitor overlap with each other. The thickness of a dielectric of the second capacitor is preferably larger than the thickness of a dielectric of the first capacitor.

A semiconductor device capable of generating a signal (e.g., a potential signal or a current signal) suitable for usage environment or a purpose. The semiconductor device includes a first memory circuit, a first circuit, and a second memory circuit. The first circuit converts a digital signal input from the first memory circuit into an analog signal. The first memory circuit includes an input node, an output node, a transistor, and a capacitor. The capacitor is electrically connected to the output node. The transistor can control a conduction state between the input node and the output node. An analog signal is input to the input node from the first circuit. The transistor includes an oxide semiconductor layer where a channel formation region is formed.