Methods, systems, and devices for techniques for memory cells with sidewall and bulk regions in planar structures are described. A memory cell may include a first electrode, a second electrode, and a self-selecting storage element between the first electrode and the second electrode. A conductive path between the first electrode and the second electrode may extend in a direction away from a plane defined by a substrate. The self-selecting storage element may include a bulk region and a sidewall region. The bulk region may include a chalcogenide material having a first composition, and the sidewall region may include the chalcogenide material having a second composition that is different than the first composition. The bulk region and sidewall region may extend between the first electrode and the second electrode and in the direction away from the plane defined by the substrate.

Methods, systems, and devices for techniques that support sidewall structures for memory cells in vertical structures are described. A memory cell may include a first electrode, a second electrode, and a self-selecting storage element between the first electrode and the second electrode. The self-selecting storage element may extend between the first electrode and the second electrode in a direction that is parallel with a plane defined by the substrate. The self-selecting storage element may also include a bulk region and a sidewall region. The bulk region may include a chalcogenide material having a first composition, and the sidewall region may include the chalcogenide material having a second composition that is different than the first composition. Also, the sidewall region may extend between the first electrode and the second electrode.

A semiconductor device that can perform product-sum operation with low power is provided. The semiconductor device includes a switching circuit. The switching circuit includes first to fourth terminals. The switching circuit has a function of selecting one of the third terminal and the fourth terminal as electrical connection destination of the first terminal, and selecting the other of the third terminal and the fourth terminal as electrical connection destination of the second terminal, on the basis of first data. The switching circuit includes a first transistor and a second transistor each having a back gate. The switching circuit has a function of determining a signal-transmission speed between the first terminal and one of the third terminal and the fourth terminal and a signal-transmission speed between the second terminal and the other of the third terminal and the fourth terminal on the basis of potentials of the back gates. The potentials are determined by second data. When signals are input to the first terminal and the second terminal, a time lag between the signals output from the third terminal and the fourth terminal is determined by the first data and the second data.

The method includes setting conductances for corresponding non-volatile memory (NVM) devices of a cross-bar array to zero. The method further includes determining a plurality of pulse-widths for the corresponding plurality of NVM devices based on a corresponding plurality of programming errors. Additionally, the method includes programming the NVM devices using the determined pulse-widths. Also, the method includes measuring actual conductances for the corresponding NVM devices. Further, the method includes adjusting scaling factors for the corresponding NVM devices based on the actual conductances and the corresponding programming errors. Additionally, the method includes programming the corresponding NVM devices based on the determined pulse-widths and the scaling factors.

A memory circuit configured to perform multiply-accumulate (MAC) operations for performance of an artificial neural network includes a series of synapse cells arranged in a cross-bar array. Each cell includes a memory transistor connected in series with a memristor. The memory circuit also includes input lines connected to the source terminal of the memory transistor in each cell, output lines connected to an output terminal of the memristor in each cell, and programming lines coupled to a gate terminal of the memory transistor in each cell. The memristor of each cell is configured to store a conductance value representative of a synaptic weight of a synapse connected to a neuron in the artificial neural network, and the memory transistor of each cell is configured to store a threshold voltage representative of a synaptic importance value of the synapse connected to the neuron in the artificial neural network.

A semiconductor storage device includes a first wiring, a second wiring, an insulating portion, and a resistance changing film. The first wiring extends in a first direction. The second wiring extends in a second direction intersecting the first direction, and is provided at a location different from that of the first wiring in a third direction intersecting the first direction and the second direction. The insulating portion is provided between the first wiring and the second wiring in the third direction. The resistance changing film is provided between the first wiring and the second wiring in the third direction, is adjacent to the insulating film from a first side and a second side which is opposite to the first side in the first direction, and the resistance changing film being smaller than the second wiring in the first direction.

A method for fabricating memory device is provided. The method includes forming a transistor on a substrate. Further, a contact structure is formed on a source/drain region of the transistor. A conductive layer is formed on the contact structure. Four memory structures are formed on the conductive layer to form a quadrilateral structure.

According to one embodiment, a semiconductor memory device includes: a first and a second wirings; a third wiring disposed between them; a first phase change layer disposed between the first and the third wirings; a first conducting layer disposed on a first wiring side surface of the first phase change layer; a second conducting layer disposed on a third wiring side surface of the first phase change layer; a second phase change layer disposed between the third and the second wirings; a third conducting layer disposed on a third wiring side surface of the second phase change layer; and a fourth conducting layer disposed on a second wiring side surface of the second phase change layer. The first and the fourth conducting layers have coefficients of thermal conductivity larger or smaller than the coefficients of thermal conductivity of the second and the third conducting layers.

Methods, systems, and devices for restoring memory cell threshold voltages are described. A memory device may perform a write operation on a memory cell during which a logic state is stored at the memory cell. Upon detecting satisfaction of a condition, the memory device may perform a read refresh operation on the memory cell during which the threshold voltage of the memory cell may be modified. In some cases, the duration of the read refresh operation may be longer than the duration of a read operation performed by the memory device on the memory cell or on a different memory cell.

Methods and apparatus are disclosed for managing the storage of dynamic neural network data within bit-addressable memory devices, such phase change memory (PCM) arrays or other storage class memory (SCM) arrays. In some examples, a storage controller determines an expected amount of change within data to be updated. If the amount is below a threshold, an In-place Write is performed using bit-addressable writes via individual SET and RESET pulses. Otherwise, a modify version of an In-place Write is performed where a SET pulse is applied to preset a portion of memory to a SET state so that individual bit-addressable writes then may be performed using only RESET pulses to encode the updated data. In other examples, a storage controller separately manages static and dynamic neural network data by storing the static data in a NAND-based memory array and instead storing the dynamic data in a SCM array.