Abstract: A read activity detector circuit for use in a random access memory array includes a plurality of synchronizer circuits operative to receive a plurality of respective reference clock signals having a frequency that is substantially the same as a core reference clock and having different phases relative to one another. Each of the synchronizer circuits, in response to a first control signal presented thereto, generates an output signal having a rising edge or a falling edge which is substantially aligned to a rising edge or a falling edge of the reference clock signal corresponding thereto. The activity detector circuit further includes a controller operative to receive the respective output signals from the plurality of synchronizer circuits and to generate an output signal as a function thereof which is indicative of data to be read from the random access memory array.

Abstract: In a thyristor based memory cell, one end of a reversed-biased diode is connected to the cathode of the thyristor. During standby, the second end of the diode is biased at a voltage that is higher than that at the cathode of the thyristor. During restore operation, the second end is pulled down to zero or even a negative value. If the cell is storing a “1,” the voltage at the thyristor cathode can be approximately 0.6 volt at the time of the pull down. The large forward-bias across the diode pulls down the thryistor cathode. This causes the thyristor to be restored. If the cell is storing a “0,” the voltage at the thyristor cathode can be approximately zero volt. The small or zero forward-bias across the diode is unable to disturb the “0” state. As a result, the memory cell is restored to its original state.

Abstract: A negative differential resistance (NDR) field-effect transistor element is disclosed, formed on a silicon-based substrate using conventional MOS manufacturing operations. Methods for improving a variety of NDR characteristics for an NDR element, such as peak-to-valley ratio (PVR), NDR onset voltage (VNDR) and related parameters are also disclosed.

Abstract: A reference cell produces a reference current that is about half of the current produced by a memory cell. The reference cell is essentially the same as the memory cell with an additional current reduction device that can be a transistor. Adjusting a reference voltage applied to the transistor allows the reference current to be varied. A control circuit to produce the reference voltage includes dedicated memory and reference cells and a feedback circuit that compares the two cells' currents. The feedback circuit applies the reference voltage to the reference cell of the control circuit and adjusts the reference voltage until the current from the reference cell is about half of the current from the memory cell. The reference voltage is then applied to other reference cells in a memory array.

Abstract: A negative differential resistance (NDR) field-effect transistor element is disclosed, formed on a silicon-based substrate using conventional MOS manufacturing operations. Methods for improving a variety of NDR characteristics for an NDR element, such as peak-to-valley ratio (PVR), NDR onset voltage (VNDR) and related parameters are also disclosed.

Abstract: A reference cell produces a reference current that is about half of the current produced by a memory cell. The reference cell is essentially the same as the memory cell with an additional current reduction device that can be a transistor. Adjusting a reference voltage applied to the transistor allows the reference current to be varied. A control circuit to produce the reference voltage includes dedicated memory and reference cells and a feedback circuit that compares the two cells' currents. The feedback circuit applies the reference voltage to the reference cell of the control circuit and adjusts the reference voltage until the current from the reference cell is about half of the current from the memory cell. The reference voltage is then applied to other reference cells in a memory array.

Abstract: The invention relates to a DNR (differential negative resistance) exhibiting device that can be programmed to store information as readable current amplitudes and to methods of making such a device. The stored data is semi-volatile. Generally, information written to a device in accordance with the invention can maintain its memory for a matter of minutes, hours, or days before a refresh is necessary. The power requirements of the device are far reduced compared to DRAM. The memory function of the device is highly stable, repeatable, and predictable. The device can be produced in a variety of ways.

Abstract: A dynamically-operating restoration circuit is used to apply a voltage or current restore pulse signal to thyristor-based memory cells and therein restore data in the cell using the internal positive feedback loop of the thyristor. In one example implementation, the internal positive feedback loop in the thyristor is used to restore the conducting state of a device after the thyristor current drops below the holding current. A pulse and/or periodic waveform are defined and applied to ensure that the thyristor is not released from its conducting state. The time average of the periodic restore current in the thyristor may be lower than the holding current threshold. While not necessarily limited to memory cells that are thyristor-based, various embodiments of the invention have been found to be the particularly useful for high-speed, low-power memory cells in which a thin capacitively-coupled thyristor is used to provide a bi-stable storage element.

Abstract: An integrated circuit is disclosed which includes a variety of NDR devices having different characteristics. The different NDR devices are formed to have different PVRs, different onset NDR voltages, etc. in a common substrate, by controlling various conventional processing operations, such as an implant, an anneal, an insulator film deposition, and the like.

Abstract: A multiple-level memory cell including a storage element formed of several polysilicon resistors connected in series between two input/output terminals; and a load in series with said resistive element, the midpoint of this series connection forming a read terminal of the memory cell, and the respective junction points of said resistors of the storage element being accessible.

Abstract: A variety of processes are disclosed for controlling NDR characteristics for an NDR element, such as peak-to-valley ratio (PVR), NDR onset voltage (VNDR) and related parameters. The processes are based on conventional semiconductor manufacturing operations so that an NDR device can be fabricated using silicon based substrates and along with other types of devices.

Abstract: A negative differential resistance (NDR) field-effect transistor element is disclosed, formed on a silicon-based substrate using conventional MOS manufacturing operations. Methods for improving a variety of NDR characteristics for an NDR element, such as peak-to-valley ratio (PVR), NDR onset voltage (VNDR) and related parameters are also disclosed.

Abstract: A circuit and a method are provided for facilitating control of bit lines in preparation for, or during, sense amplification of data signals from thinly capacitively-coupled thyristor (“TCCT”)-based memory cells. In accordance with a specific embodiment, a circuit and method are designed, among other things, to effectively minimize power consumption by memory cells and to increase speed and reliability of sense amplification. In another specific embodiment, the circuit and method are directed to TCCT-based memory cells.

Abstract: In a thyristor based memory cell, one end of a reversed-biased diode is connected to the cathode of the thyristor. During standby, the second end of the diode is biased at a voltage that is higher than that at the cathode of the thyristor. During restore operation, the second end is pulled down to zero or even a negative value. If the cell is storing a “1,” the voltage at the thyristor cathode can be approximately 0.6 volt at the time of the pull down. The large forward-bias across the diode pulls down the thryistor cathode. This causes the thyristor to be restored. If the cell is storing a “0,” the voltage at the thyristor cathode can be approximately zero volt. The small or zero forward-bias across the diode is unable to disturb the “0” state. As a result, the memory cell is restored to its original state.

Abstract: A memory device (such as an SRAM) using negative differential resistance (NDR) elements is disclosed. Body effect performances for NDR FETs (and other FETs) that may be used in such device are enhanced by floating a body of some/all the NDR FETs. Various embodiments using common or separate wells for such elements are illustrated to achieve superior body effect performance results, including a silicon-on-insulator (SOI) implementation.

Abstract: A dynamically-operating restoration circuit (106) is used to apply a voltage or current restore pulse signal to thyristor-based memory cells (108) and therein restore data in the cell using the internal positive feedback loop of the thyristor (110). In one example implementation, the internal positive feedback loop in the thyristor (110) is used to restore the conducting state of a device after the thyristor current drops below the holding current. A pulse and/or periodic waveform are defined and applied to ensure that the thyristor is not released from its conducting state. The time average of the periodic restore current in the thyristor may be lower than the holding current threshold. While not necessarily limited to memory cells that are thyristor-based, various embodiments of the invention have been found to be the particularly useful for high-speed, low-power memory cells in which a thin capacitively-coupled thyristor is used to provide a bi-stable storage element.

Abstract: A charge trapping device, and a method of forming the same is disclosed. Charge traps are optimally distributed through a trapping region based on controlling various conventional processing operations, such as an implant, an anneal, an insulator film deposition, and the like. In some embodiments, FETs can be configured to include a negative differential resistance (NDR) characteristic when they utilize a particular charge trap energy and distribution.

Abstract: A reference cell produces a voltage rise on a bit line that is proportional to, and preferably half of, the voltage rise on another bit line produced by a TCCT based memory cell in an “on” state. The reference cell includes an NDR device, a gate-like device disposed adjacent to the NDR device, a first resistive element coupled between the NDR device and the bit line, and a second resistive element coupled between a sink and the bit line. Resistances of the first and second resistive elements are about equal and about twice as much as the resistance of a pass transistor of the a TCCT based memory cell.

Abstract: A content addressable memory (CAM) cell includes a memory cell storing data values. The memory cell includes a surrounding-gate thyristor and an access transistor. The CAM cell also includes a compare circuit coupled among the memory cell and a match line. The compare circuit receives data and comparand data and affects a logical state of a match line in response to a predetermined relationship between the data and comparand data. The compare circuit includes a first transistor set coupled for conduction state control by signals representative of the data, and a second transistor set coupled for conduction state control by signals representative of the comparand data.

Abstract: A method of testing/stressing a charge trapping device, such as a negative differential resistance (NDR) FET is disclosed. By operating/stressing a charge trap device during/after manufacture, a distribution of charge traps can be altered advantageously to improve performance.

Abstract: The invention relates to a DNR (differential negative resistance) exhibiting device that can be programmed to store information as readable current amplitudes and to methods of making such a device. The stored data is semi-volatile. Generally, information written to a device in accordance with the invention can maintain its memory for a matter of minutes, hours, or days before a refresh is necessary. The power requirements of the device are far reduced compared to DRAM. The memory function of the device is highly stable, repeatable, and predictable. The device can be produced in a variety of ways.

Abstract: A two terminal, silicon based negative differential resistance (NDR) element is disclosed, to effectuate a type of NDR diode for selected applications. The two terminal device is based on a three terminal NDR-capable FET which has a modified channel doping profile, and in which the gate is tied to the drain. This device can be integrated through conventional CMOS processing with other NDR and non-NDR elements, including NDR capable FETs. A memory cell using such NDR two terminal element and an NDR three terminal is also disclosed.

Abstract: A memory cell is formed by an FET, a gate of which is connected to the word line and a drain of which is connected to the bit line; a capacitor, one end of which is connected to a source of the FET and the other end of which is connected to a first power supply; a first negative differential resistance element provided between the word line and the source of the FET; and a second negative differential resistance element provided between the source of the FET and a second power supply.

Abstract: The present invention provides a circuit and a method for providing nondestructive write operations and optimized memory access operations with reduced power consumption during memory access, such as during write operations. In one embodiment, a memory device comprises a memory cell configured to store a first data bit. The memory device also comprises a write access circuit coupled to the memory cell for providing a write data bit having a write data bit magnitude. The write access circuit is configured to adjust the write data bit magnitude to an intermediate logic state magnitude in a memory operation.

Abstract: A memory cell using both negative differential resistance (NDR) and conventional FETs is disclosed. A pair of NDR FETs are coupled in a latch configuration so that a data value passed by a transfer FET can be stored at a storage node. By exploiting an NDR characteristic, the memory cell can be implemented with fewer active devices. Moreover, an NDR FET can be manufactured using conventional MOS processing steps so that process integration issues are minimized as compared to conventional NDR techniques.

Abstract: A DMOS device is provided which is equipped with a floating gate having a first and second electrode in close proximity thereto. The floating gate is separated from one of the first and second electrodes by a thin layer of dielectric material whose dimensions and composition permit charge carriers to tunnel through the dielectric layer either to or from the floating gate. This tunneling phenomenon can be used to create a threshold voltage that may be adjusted to provide a precise current by placing a voltage between a programming electrode and the body/source and gate electrode of the device.

Abstract: A silicon-on-insulator (SOI) memory device (such as an SRAM) using negative differential resistance (NDR) elements is disclosed. Body effect performances for NDR FETs (and other FETs) that may be used in such device are enhanced by floating a body of some/all the NDR FETs.

Abstract: A reference cell produces a voltage rise on a bit line that is proportional to, and preferably half of, the voltage rise on another bit line produced by a TCCT based memory cell in an “on” state. The reference cell includes an NDR device, a gate-like device disposed adjacent to the NDR device, a first resistive element coupled between the NDR device and the bit line, and a second resistive element coupled between a sink and the bit line. Resistances of the first and second resistive elements are about equal and about twice as much as the resistance of a pass transistor of the a TCCT based memory cell.

Abstract: An integrated circuit device includes a charge pump for providing a bias signal to a field effect transistor (FET) that is capable of operating in a negative differential resistance mode. The bias signal is applied to a gate of the NDR FET to control the characteristics of the NDR behavior.

Abstract: A pair of cross-coupled inverters that hold a digital state are powered by supplies that also function as row select and column bit lines. A method of reading and writing the digital state of an individual cell, row of cells, or column of cells by manipulating these row-supply or column-supply lines. Reads and writes may be performed on either a row or column basis. A method for reading and logically OR'ing or AND'ing an entire row or column of cells. A method for querying on a row or column basis to function as a content addressable memory (CAM).

Abstract: Provided is a semiconductor memory having a memory cell structure capable of reducing soft error without complicating a circuit configuration. Specifically, an inverter (I1) consists of a NMOS transistor (N1) and a PMOS transistor (P1), and an inverter (I2) consists of a NMOS transistor (N2) and a PMOS transistor (P2). The inverters (I1, I2) are subjected to cross section. The NMOS transistor (N1) is formed within a P well region (PW0), and the NMOS transistor (N2) is formed within a P well region (PW1). The P well regions (PW0, PW1) are oppositely disposed with an N well region (NW) interposed therebetween.

Abstract: An active negative differential resistance element (an NDR FET) and a memory device (such as an SRAM) using such elements is disclosed. Soft error rate (SER) performance for NDR FETs and such memory devices are enhanced by adjusting a location of charge traps in a charge trapping layer that is responsible for effectuating an NDR behavior. Both an SER and a switching speed performance characteristic can be tailored by suitable placement of the charge traps.

Abstract: The present invention is directed to novel antifuse arrays and their methods of fabrication. According to an embodiment of the present invention an array comprises a plurality of first spaced apart rail-stacks having a top semiconductor material. A fill dielectric is located between the first plurality of spaced apart rail-stacks wherein the fill dielectric extends above the top surface of the semiconductor material. An antifuse material is formed on the top of the semiconductor material of the first plurality of spaced apart rail-stacks. A second plurality of spaced apart rail-stacks having a lower semiconductor material is formed on the antifuse material. In the second embodiment of the present invention the array comprises a first plurality of spaced apart rail-stacks having a top semiconductor material. A fill dielectric is located between the first plurality of spaced apart rail-stacks wherein the fill dielectric is recessed below the top surface of the semiconductor material.

Abstract: A semiconductor memory having a memory cell structure capable of reducing soft error without complicating a circuit configuration. Specifically, an inverter includes a NMOS transistor and a PMOS transistor, and an inverter includes a NMOS transistor and a PMOS transistor. The inverters are subjected to cross section. The NMOS transistor is formed within a P well region, and NMOS transistor is formed within a P well region. The P well regions are oppositely disposed with an N well region interposed therebetween.

Abstract: A memory cell is formed by an FET, a gate of which is connected to the word line and a drain of which is connected to the bit line; a capacitor, one end of which is connected to a source of the FET and the other end of which is connected to a first power supply; a first negative differential resistance element provided between the word line and the source of the FET; and a second negative differential resistance element provided between the source of the FET and a second power supply.

Abstract: A passive element memory array preferably biases selected X-lines to an externally received VPP voltage and selected Y-lines to ground. Unselected Y-lines are preferably biased to VPP minus a first offset voltage, and unselected X-lines biased to a second offset voltage (relative to ground). The first and second offset voltages preferably are identical and have a value of about 0.5 to 2 volts. The VPP voltage depends upon the memory cell technology used, and preferably falls within the range of 5 to 20 volts. The area otherwise required for an on-chip VPP generator and saves the power that would be consumed by such a generator. In addition, the operating temperature of the integrated circuit during the programming operation decreases, which further decreases power dissipation. When discharging the memory array, the capacitance between layers is preferably discharged first, then the layers are discharged to ground.

Abstract: A negative differential resistance device is provided that includes a first barrier, a second barrier and a third barrier. A first quantum well is formed between the first and second barriers. A second quantum well is formed between the second and third barriers.

Abstract: An integrated circuit device includes a charge pump for providing a bias signal to a field effect transistor (FET) that is capable of operating in a negative differential resistance mode. The bias signal is applied to a gate of the NDR FET to control the characteristics of the NDR behavior.

Abstract: A negative resistance device (NRD) has a MOSFET-like structure, and is biased by shorting the gate and source together at a fixed applied potential and applying a different fixed potential to the drain, and sweeping the bulk potential towards the drain potential, causing the bulk current to exhibit a negative resistance characteristic. The NRD may be used in a memory circuit (10) in which a resistor (R) is connected between the bulk (2) and a fixed potential. Two States of the circuit at which the current through the resistor matches that through the bulk of the NRD are stable, providing for bistable memory operation.

Abstract: A semiconductor memory which can secure the stability of data holding characteristics and data read/write characteristics for a tunnel diode having a small peak/valley ratio, and to provide a method for manufacturing such a semiconductor memory. The peak/valley ratio of a tunnel diode can be improved by arranging a tunnel insulating film on the bottom portion of the ground direct contact forming the tunnel diode; the resistance of high resistance load can further be increased by arranging a tunnel insulating film on the bottom portion of the storage node direct contact; and data holding characteristics can be improved while controlling the column current by setting the power voltage impressed to the high resistance load higher than the power voltage impressed to the bit line.

Abstract: A SRAM memory cell including two tunnel diodes coupled in series and a MOS FET. A first of the tunnel diodes may be formed in a shallow trench. A second of the tunnel diodes may be formed in a source or drain contact region of the FET. The FET acts as a pass gate to allow data to be read from or written to the memory cell when the gate of the FET is biased to turn the FET ON. The FET otherwise acts to prevent the datum stored in the memory cell from being altered when the FET is turned OFF. The memory cell may be formed to be unusually compact and has a reduced power supply requirements compared to conventional SRAM memory cells. As a result, a compact and robust SRAM having reduced standby power requirements is realized.

Abstract: A negative resistance device (NRD) has a MOSFET-like structure, and is biased by:

Abstract: A SRAM memory cell including two tunnel diodes coupled in series and a MOS FET. A first of the tunnel diodes may be formed in a shallow trench. A second of the tunnel diodes may be formed in a source or drain contact region of the FET. The FET acts as a pass gate to allow data to be read from or written to the memory cell when the gate of the FET is biased to turn the FET ON. The FET otherwise acts to prevent the datum stored in the memory cell from being altered when the FET is turned OFF. The memory cell may be formed to be unusually compact and has a reduced power supply requirements compared to conventional SRAM memory cells. As a result, a compact and robust SRAM having reduced standby power requirements is realized.

Abstract: A static memory cell having no more than three transistors. A static memory cell comprises a semiconductor substrate of a first conductivity type; a buried layer in the substrate, the buried layer having a second conductivity type opposite to the first conductivity type; a transistor formed over the buried layer, the transistor having a source of the second conductivity type, a gate, and a drain of the second conductivity type, the source having a depth in the substrate greater than the depth of the drain; and alternating layers of insulative and conductive material formed proximate the source, including two conductive layers and two insulative layers, one of the insulative layers being in junction relation to the source.

Abstract: A memory system is organized as a matrix including a memory cell at each intersection of a bit line with write and read word lines Each memory cell comprises a first FET 20 having its gate coupled to a write word line and its drain coupled to a bit line, a second FET 22 having its source coupled to the bit line and its drain coupled to a read word line, and first and second negative resistance devices 24,26 coupled in series between a supply voltage and a substrate voltage, the common point SN of the series-connected negative resistance devices being coupled to the source of the first PET and to the gate of the second FET. Preferably, the first FET 20 is a p-channel device, the second FET 22 is an n-channel device, and the first and second negative resistance devices 24,26 are RTDs. In a second embodiment, a memory system has a memory cell at each intersection of a bit line with a word line.

Abstract: A memory cell of an SRAM includes an access transistor, and an MIS switching diode. The access transistor has a drain electrode connected to a bit line of a corresponding column, a source electrode connected to a storage node, and a gate electrode connected to a word line of a corresponding row. The threshold voltage of the access transistor is small than the threshold voltage of a bit line load transistor. The MIS switching diode is connected between the storage node and a second power supply potential node. The switching initiate voltage of the MIS switching diode is greater than the difference between the first potential and the threshold voltage of the bit line load transistor, and smaller than the difference between the first potential and the threshold voltage of the access transistor. Thus, data can be read/written and held accurately.

Abstract: A memory array circuit has two memory sections. Each memory section has a matrix of column lines and row lines. A plurality of memory cells are arranged in the matrix, with each memory cell comprising a tunnel diode connected in series with a load, with a data node therebetween. The impedance characteristics of the tunnel diode and the load is such that at the data node, they intersect to form two or more points of stability. In one embodiment, a conventional access transistor is used to write data into and to read data out of the memory cell. In another embodiment an avalanche diode is used to write data into and to read data out of the memory cell.

Abstract: A transistorless memory cell for storing information as one of two possible bistable current states comprises (i) at least one first transistorless device exhibiting N-type negative differential resistance, including a high-impedance region, a low-impedance region and a negative-resistance region and having a polarity and (ii) at least one second transistorless device exhibiting an exponential or linear current-voltage characteristic and coupled to the first transistorless device. The read/write operation of the transistorless memory cell is performed in a current mode.

Abstract: A memory cell of an SRAM includes an access transistor, and an MIS switching diode. The access transistor has a drain electrode connected to a bit line of a corresponding column, a source electrode connected to a storage node, and a gate electrode connected to a word line of a corresponding row. The threshold voltage of the access transistor is small than the threshold voltage of a bit line load transistor. The MIS switching diode is connected between the storage node and a second power supply potential node. The switching initiate voltage of the MIS switching diode is greater than the difference between the first potential and the threshold voltage of the bit line load transistor, and smaller than the difference between the first potential and the threshold voltage of the access transistor. Thus, data can be read/written and held accurately.

Abstract: An n-type diffusion layer, an insulating layer and a first aluminum electrode are formed on a p-type silicon substrate. Fe.sup.2+ (divalent Fe) having a vacant orbit not filled with an electron is implanted into a region of the insulating layer to form an impurity atom layer. A second aluminum electrode is formed which is in contact with the n-type diffusion layer. A voltage that increases the potential of the first aluminum electrode is applied between the first and second aluminum electrodes. The voltage is increased. In this situation, when the fermi level of the n-type diffusion layer and an impurity level which is the energy level for filling the vacant orbit of the Fe.sup.2+ are matched, a resonance tunnelling current flows. Thereafter, when there is a change to the state of non-resonance state, a negative-resistance characteristic is exhibited in which the current decreases as the voltage is increased.