摘要:
A system of Flash EEprom memory chips with controlling circuits serves as non-volatile memory such as that provided by magnetic disk drives. Improvements include selective multiple sector erase, in which any combinations of Flash sectors may be erased together. Selective sectors among the selected combination may also be de-selected during the erase operation. Another improvement is the ability to remap and replace defective cells with substitute cells. The remapping is performed automatically as soon as a defective cell is detected. When the number of defects in a Flash sector becomes large, the whole sector is remapped. Yet another improvement is the use of a write cache to reduce the number of writes to the Flash EEprom memory, thereby minimizing the stress to the device from undergoing too many write/erase cycling.
摘要:
An improved electrically erasable and programmable read only memory (EEprom) structure and processes of making it which results in a denser integrated circuit, improved operation and extended lifetime. In order to eliminate certain ill effects resulting from tolerances which must be allowed for registration of masks used in successive steps in forming the semiconductor structures, spacers are formed with reference to the position of existing elements in order to form floating gates and define small areas of these gates where, in a controlled fashion, a tunnel erase dielectric is formed. Alternatively, a polysilicon strip conductor is separated into separate control gates by a series of etching steps that includes an anisotropic etch of boundary oxide layers to define the area of the control gates that are coupled to the erase gate through an erase dielectric. In either case, the polysilicon layer strip can alternatively be separated by growing oxide thereon until it is completely consumed. A technique for forming a pure oxide dielectric layer of uniform thickness includes depositing a thin layer of an undoped polysilicon material and then oxidizing its surface until substantially the entire undoped polysilicon layer is consumed and made part of the resulting oxide layer. Overlapping doped regions are provided in the substrate by an ion implantation mask that adds spacers to the mask aperture to change its size between implants.
摘要:
A vertical trench etched several microns deep into the silicon extending into a buried diffusion region is used to confine a vertical interconnect element. This element can be a high resistivity undoped polycrystalline silicon load resistor, a medium resistivity doped polycrystalline silicon load resistor, or a low resistivity interconnect to the buried diffusion region. This new structure can be used in compact and scalable MOS and bipolar inverters and in bistable memory storage cells.
摘要:
A memory cell comprises a substrate of a first conductivity type (preferably N type) in which is formed a first region of opposite conductivity type. Second, third and fourth regions of first conductivity type are then formed in the first region, said second and third regions being separated by a first portion of the first region and said third and fourth regions being separated by a second portion of the first region. A fifth region of first conductivity type is then formed in the second portion of the first region and a first electrode is attached to the fifth region. This electrode is electrically isolated from the second, third and fourth regions and extends on insulation over the first portion of said first region to said second region and also extends over said third region and a part of the second portion of said first region. This electrode is covered by insulation. A word line is then formed over the insulation on the first electrode so as to overlie the first electrode and together with the first electrode forms a dual electrode. The dual electrode structure forms a read transistor with channel length measured by the extent of the first portion between said second region and said third region and a write transistor with channel length measured by the separation between said third region and said fifth region, and a storage junction formed between said fifth region and said first region. By varying the voltage on the third region during the driving of the word line to either a positive or negative voltage, the charge on the first electrode is varied thereby varying the threshold voltage of the read transistor as seen by the word line. A plurality of memory cells such as described can be used to form an array and by varying either the capacitive coupling between the word line or third region and the first electrode in a selected memory cell or, alternatively, by varying the voltage applied to the third region during the writing on said first electrode of stored charge, this particular cell can be used as a reference cell during the read operation.
摘要:
The floating gate in an N channel EPROM cell extends over the drain diffusion and over a portion of the channel thereby to form a "drain" capacitance between the drain and the floating gate and a "channel" capacitance between the channel and the floating gate. A control gate overlaps the floating gate and extends over the remainder of the channel near the source diffusion thereby to form a "control" capacitance between the channel and the control gate. These three capacitances form the coupling for driving each cell. The inversion region in the channel directly under the control gate is established directly by a "write or read access" voltage applied to the control gate. The inversion region in the channel directly under the floating gate is established indirectly through the drain and control capacitances and the channel capacitance by the control gate voltage and by another write access voltage applied to the drain. In effect, the drain voltage is coupled to the portion of the channel adjacent to the drain through the series driving circuit formed by the drain capacitance and the channel capacitance. During write, hot electrons from the write channel current are directed toward and injected into the floating gate by the transverse electric field between the floating gate and the underlying channel. Stored injection charge on the floating gate raises the conduction threshold of the programmed cell, causing the cell to remain nonconductive during read when standard ("low") access voltages are applied to the control gate. An unprogrammed cell conducts in response to the low read voltages applied to its control gate and drain drive circuit. A cell is erased either by ultraviolet illumination or by electrons from the floating gate tunneling through a region of thinned oxide. The non-symmetrical arrangement of the control gate and floating gate with respect to source and drain allows a very dense array implementation.
摘要:
The specification describes an integrated device for the input protection of MOS circuits. It consists of an MOS capacitor formed by the thinning of a section of the input gate dielectric, SiO.sub.2, and the thinning of an adjoining section of the gate metal, Al. An incoming pulse of static charge with high amplitude and short duration will break down the thinned dielectric of the capacitor before breaking down the relatively thick portion of the gate dielectric. Since the metal over the thin dielectric is also relatively thin, it evaporates from the vicinity of the fault by the generated Joule heat immediately following the breakdown. Thus, the breakdown is self healed and can be repeated many times without damaging the circuit.
摘要:
An integrated non-volatile memory circuit is formed by first growing a thin dielectric layer on a semiconductor substrate surface, followed by depositing a layer of conductive material such as doped polysilicon on this dielectric layer, the conductive material then being separated into rows and columns of individual floating gates. Cell source and drain diffusions in the substrate are continuously elongated across the rows. Field dielectric deposited between the rows of floating gates provides electrical isolation between the rows. Shallow trenches may be included between rows without interrupting the conductivity of the diffusions along their lengths. A deep dielectric filled trench is formed in the substrate between the array and peripheral circuits as electrical isolation. Various techniques are included that increase the field coupling area between the floating gates and a control gate. Other techniques increase the thickness of dielectric between control gates in order to decrease the field coupling between them.
摘要:
A peripheral card having a Personal Computer (“PC”) card form factor and removably coupled externally to a host system is further partitioned into a mother card portion and a daughter card portion. The daughter card is removably coupled to the mother card. In the preferred embodiment, a low cost flash “floppy” is accomplished with the daughter card containing only flash EEPROM chips and being controlled by a memory controller residing on the mother card. Other aspects of the invention includes a comprehensive controller on the mother card able to control a predefined set of peripherals on daughter cards connectable to the mother card; relocation of some host resident hardware to the mother card to allow for a minimal host system; a mother card that can accommodate multiple daughter cards; daughter cards that also operates directly with hosts having embedded controllers; daughter cards carrying encoded data and information for decoding it; and daughter cards with security features.
摘要:
A three-dimensional non-volatile memory system is disclosed including a memory array utilizing shared pillar structures for memory cell formation. A shared pillar structure includes two non-volatile storage elements. A first end surface of each pillar contacts one array line from a first set of array lines and a second end surface of each pillar contacts two array lines from a second set of array lines that is vertically separated from the first set of array lines. Each pillar includes a first subset of layers that are divided into portions for the individual storage elements in the pillar. Each pillar includes a second subset of layers that is shared between both non-volatile storage elements formed in the pillar. The individual storage elements each include a steering element and a state change element.
摘要:
A NAND controller for interfacing between a host device and a flash memory device (e.g., a NAND flash memory device) fabricated on a flash die is disclosed. In some embodiments, the presently disclosed NAND controller includes electronic circuitry fabricated on a controller die, the controller die being distinct from the flash die, a first interface (e.g. a host-type interface, for example, a NAND interface) for interfacing between the electronic circuitry and the flash memory device, and a second interface (e.g. a flash-type interface) for interfacing between the controller and the host device, wherein the second interface is a NAND interface. According to some embodiments, the first interface is an inter-die interface. According to some embodiments, the first interface is a NAND interface. Systems including the presently disclosed NAND controller are also disclosed. Methods for assembling the aforementioned systems, and for reading and writing data using NAND controllers are also disclosed.