Multi-gate NOR flash thin-film transistor (TFT) string arrays (“multi-gate NOR string arrays”) are organized as stacks of horizontal active strips running parallel to the surface of a silicon substrate, with the TFTs in each stack being controlled by vertical local word-lines provided along one or both sidewalls of the stack of active strips. Each active strip includes at least a channel layer formed between two shared source or drain layers. Data storage in the TFTs of an active strip is provided by charge-storage elements provided between the active strip and the control gates provided by the adjacent local word-lines. Each active strip may provide TFTs that belong to one or two NOR strings, depending on whether one or both sides of the active strip are used.

Systems and methods disclosed herein are related to a memory system. In one aspect, the memory system includes a first set of memory cells and a second set of memory cells; a first group of switches, each including: a first electrode connected to first electrodes of the first subset of memory cells, and a second electrode; a second group of switches, each including: a first electrode connected to first electrodes of the second subset of memory cells, and a second electrode; and a third group of switches, each including: a first electrode connected to a first global bit line, and a second electrode connected to the second electrodes of the first group of switches and the second electrodes of the second group of switches.

A memory structure, includes (a) active columns of polysilicon formed above a semiconductor substrate, each active column extending vertically from the substrate and including a first heavily doped region, a second heavily doped region, and one or more lightly doped regions each adjacent both the first and second heavily doped region, wherein the active columns are arranged in a two-dimensional array extending in second and third directions parallel to the planar surface of the semiconductor substrate; (b) charge-trapping material provided over one or more surfaces of each active column; and (c) conductors each extending lengthwise along the third direction. The active columns, the charge-trapping material and the conductors together form a plurality of thin film transistors, with each thin film transistor formed by one of the conductors, a portion of the lightly doped region of an active column, the charge-trapping material between the portion of the lightly doped region and the conductor, and the first and second heavily doped regions. The thin film transistors associated with each active column are organized into one or more vertical NOR strings.

Multi-gate NOR flash thin-film transistor (TFT) string arrays are organized as three dimensional stacks of active strips. Each active strip includes a shared source sublayer and a shared drain sublayer that is connected to substrate circuits. Data storage in the active strip is provided by charge-storage elements between the active strip and a multiplicity of control gates provided by adjacent local word-lines. The parasitic capacitance of each active strip is used to eliminate hard-wire ground connection to the shared source making it a semi-floating, or virtual source. Pre-charge voltages temporarily supplied from the substrate through a single port per active strip provide the appropriate voltages on the source and drain required during read, program, program-inhibit and erase operations. TFTs on multiple active strips can be pre-charged separately and then read, programmed or erased together in a massively parallel operation.

NOR memory strings may be used for implementations of logic functions involving many Boolean variables, or to generate analog signals whose magnitudes are each representative of the bit values of many Boolean variables. The advantage of using NOR memory strings in these manners is that the logic function or analog signal generation may be accomplished within one simultaneous read operation on the NOR memory strings.

A method in a memory circuit for rapidly determining the location of a file includes (a) associating the file with a timestamp and a unique identifier index number when the file is stored or updated in the memory circuit, and storing in a look-up table in the memory circuit the associated timestamp and an address associated with where the file is stored; (b) receiving a search request that specifies a unique identifier index number of a file to be located; and (c) using exclusive-or (XOR) circuits or content addressable memory (CAM) circuits to compare the unique identifier index number in the search request with the unique identifier index number stored in the look-up table, and reporting, when a match is found between the unique identifier index number in the search request and the unique identifier index number stored in the look-up table, the timestamp and address associated with the match.

A memory structure, includes (a) active columns of polysilicon formed above a semiconductor substrate, each active column extending vertically from the substrate and including a first heavily doped region, a second heavily doped region, and one or more lightly doped regions each adjacent both the first and second heavily doped region, wherein the active columns are arranged in a two-dimensional array extending in second and third directions parallel to the planar surface of the semiconductor substrate; (b) charge-trapping material provided over one or more surfaces of each active column; and (c) conductors each extending lengthwise along the third direction. The active columns, the charge-trapping material and the conductors together form a plurality of thin film transistors, with each thin film transistor formed by one of the conductors, a portion of the lightly doped region of an active column, the charge-trapping material between the portion of the lightly doped region and the conductor, and the first and second heavily doped regions. The thin film transistors associated with each active column are organized into one or more vertical NOR strings.

A memory structure, includes (a) active columns of polysilicon formed above a semiconductor substrate, each active column extending vertically from the substrate and including a first heavily doped region, a second heavily doped region, and one or more lightly doped regions each adjacent both the first and second heavily doped region, wherein the active columns are arranged in a two-dimensional array extending in second and third directions parallel to the planar surface of the semiconductor substrate; (b) charge-trapping material provided over one or more surfaces of each active column; and (c) conductors each extending lengthwise along the third direction. The active columns, the charge-trapping material and the conductors together form a plurality of thin film transistors, with each thin film transistor formed by one of the conductors, a portion of the lightly doped region of an active column, the charge-trapping material between the portion of the lightly doped region and the conductor, and the first and second heavily doped regions. The thin film transistors associated with each active column are organized into one or more vertical NOR strings.

A memory structure, includes (a) active columns of polysilicon formed above a semiconductor substrate, each active column extending vertically from the substrate and including a first heavily doped region, a second heavily doped region, and one or more lightly doped regions each adjacent both the first and second heavily doped region, wherein the active columns are arranged in a two-dimensional array extending in second and third directions parallel to the planar surface of the semiconductor substrate; (b) charge-trapping material provided over one or more surfaces of each active column; and (c) conductors each extending lengthwise along the third direction. The active columns, the charge-trapping material and the conductors together form a plurality of thin film transistors, with each thin film transistor formed by one of the conductors, a portion of the lightly doped region of an active column, the charge-trapping material between the portion of the lightly doped region and the conductor, and the first and second heavily doped regions. The thin film transistors associated with each active column are organized into one or more vertical NOR strings.

Multi-gate NOR flash thin-film transistor (TFT) string arrays (multi-gate NOR string arrays) are organized as stacks of horizontal active strips running parallel to the surface of a silicon substrate, with the TFTs in each stack being controlled by vertical local word-lines provided along one or both sidewalls of the stack of active strips. Each active strip includes at least a channel layer formed between two shared source or drain layers. Data storage in the TFTs of an active strip is provided by charge-storage elements provided between the active strip and the control gates provided by the adjacent local word-lines. Each active strip may provide TFTs that belong to one or two NOR strings, depending on whether one or both sides of the active strip are used.