Abstract: A static random access memory (SRAM) cell includes a SRAM circuit and a programmable resistor connected to a storage node of the SRAM circuit. The SRAM circuit can be any type of SRAM circuit, such as a 3T, negative differential resistance (NDR) transistor-based circuit, or a 6T (conventional SRAM) circuit. The programmable resistor can be formed in a metal layer above the SRAM circuit to minimize the area requirements for the memory cell. Just before shutdown of the SRAM cell, the resistance state of the programmable resistor is changed (if necessary) based on the data value stored at the storage node. The programmable resistor provides a non-volatile indication of the stored data value at the time of power off. Then, when power is restored to the SRAM cell, a data value based on the resistance state of the programmable resistor is written back into the SRAM circuit.

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 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 method of making an n-channel metal-insulator-semiconductor field-effect transistor (MISFET) that uses charge trapping for altering channel conductivity characteristics is disclosed. Other suitable and conventional processing steps are used to finalize completion of the fabrication of the charge trapping device so that the entire process is compatible and achieved with CMOS processing techniques, and so that non-charge trapping devices can be formed at the same time in a common sequence of manufacturing operations.

Abstract: A silicon based semiconductor device and method uses charge trapping to alter a density of carriers available in a channel of a field effect transistor (FET) for conduction. The charge trapping mechanism can be controlled by a source-drain bias voltages applied to the FET, so that the device can be turned off through a control mechanism separate from a gate voltage.

Abstract: A two-terminal NDR device can be formed by coupling the gate and drain of an NDR-capable FET, such that the coupled gate and drain form a first terminal and the source of the NDR-capable FET forms the second terminal. By applying an appropriate body bias between the body and source of an NDR-capable FET configured in this manner, the NDR-capable FET can be forced to operate with a negative threshold voltage, thereby allowing the resulting two-terminal device to exhibit the desired NDR characteristics. This two-terminal device can, for example, be used as a load element in a static random access memory (SRAM) cell and various other circuits where the NDR behavior of the device would be beneficial.

Abstract: Static random access memory (SRAM) performance is enhanced through the use of appropriate latch strength control. For example, latch strength in an SRAM cell is increased during data store operations to reduce power dissipation and improve reliability. Latch strength can also be increased to improve read speed, while latch strength can be reduced to improve write speed. In an SRAM cell including at least a negative differential resistance (NDR) device as a pull-up element, this type of latch control can be achieved through appropriate biasing of the NDR device(s). For example, drain-to-source bias can be increased or decreased to increase or decrease, respectively, latch strength. Similarly, gate-to-source bias can be increased or decreased to increase or decrease, respectively, latch strength.

Abstract: A silicon based semiconductor device and method uses charge trapping to alter a density of carriers available in a channel of a field effect transistor (FET) for conduction. The charge trapping mechanism can be controlled by a source-drain bias voltages applied to the FET, so that the device can be turned off through a control mechanism separate from a gate voltage.

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: 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: An enhanced method of writing and reading a memory device, such as an SRAM using negative differential resistance (NDR) elements), is disclosed. This is done through selective control of biasing of the active elements in a memory cell. For example in a write operation, a memory cell is placed in an intermediate state to increase write speed. In an NDR based embodiments, this is done by reducing a bias voltage to NDR FETs so as to weaken the NDR element (and thus disable an NDR effect) during the write operation. Conversely, during a read operation, the bias voltages are increased to enhance peak current (as well as an NDR effect), and thus provide additional current drive to a BIT line. Embodiments using such procedures achieve superior peak to valley current ratios (PVR), read/write speed, etc.

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: An n-channel field effect transistor (FET) includes a switchable negative differential resistance (SNDR) characteristic. The n-channel SNDR FET is configured as a depletion mode device, and biased so that it operates essentially as a p-channel device. The device is suitable as a replacement for a p-channel pull-up devices in logic gates (including in inverters) and memory cells.

Abstract: Static random access memory (SRAM) performance is enhanced through the use of appropriate latch strength control. For example, latch strength in an SRAM cell is increased during data store operations to reduce power dissipation and improve reliability. Latch strength can also be increased to improve read speed, while latch strength can be reduced to improve write speed. In an SRAM cell including at least a negative differential resistance (NDR) device as a pull-up element, this type of latch control can be achieved through appropriate biasing of the NDR device(s). For example, drain-to-source bias can be increased or decreased to increase or decrease, respectively, latch strength. Similarly, gate-to-source bias can be increased or decreased to increase or decrease, respectively, latch strength.

Abstract: A two terminal, silicon based negative differential resistance (NDR) element is disclosed, to effectuate 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 two-terminal NDR device can be formed by coupling the gate and drain of an NDR-capable FET, such that the coupled gate and drain form a first terminal and the source of the NDR-capable FET forms the second terminal. By applying an appropriate body bias between the body and source of an NDR-capable FET configured in this manner, the NDR-capable FET can be forced to operate with a negative threshold voltage, thereby allowing the resulting two-terminal device to exhibit the desired NDR characteristics. This two-terminal device can, for example, be used as a load element in a static random access memory (SRAM) cell and various other circuits where the NDR behavior of the device would be beneficial.

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 memory cell includes a pull-up element that exhibits a refresh behavior that is dependent on the data value stored in the memory cell. The pull-up element is an NDR FET connected between a high voltage source and a storage node of the memory cell. The NDR FET receives a pulsed gate bias signal, wherein each pulse turns on the NDR FET when a logic HIGH value is stored at the storage node, and further wherein each pulse does not turn on the NDR FET when a logic LOW value is stored at the storage node. In this fashion a DRAM cell (and device) can be operated without a separate refresh cycle.

Abstract: A CMOS based n-channel metal-insulator-semiconductor field-effect transistor (MISFET) that exhibits a useful negative differential resistance effect is disclosed. The resulting device can be incorporated into a number of useful applications, including as part of a memory device, a logic device, etc.