Abstract: An internal voltage regulator for a synchronous random access memory (“SDRAM”) uses a regulator circuit to supply power to charge pumps that is separate from a regulator circuit that supplies power to the arrays of the SDRAM. The regulator supplies an output voltage to the charge pumps that is maintained constant as the external supply voltage is increased beyond its normal operating range. In contrast, a regulated circuit that supplies power to the arrays increases as the supply voltage is increase beyond its normal operating range. As a result, the voltage regulator allows the arrays to be stress tested with a relatively high regulated output voltage without applying an excessive and potentially damaging regulated output voltage to the charge pumps.

Abstract: An electrostatic discharge protection device for integrated circuit is formed in a substrate and contains pad contact, rail contact and a deep oxide in a trench in the substrate which isolates pad and rail contacts. The substrate is doped with a first dopant type with a first concentration. A second dopant type in a first inner and a first outer region forms the pad contact; both regions are formed on the substrate. The first inner region is doped higher than the first outer region. Similarly a second dopant type in a second inner and a second outer region forms the rail contact; both regions are formed on the substrate. The second inner region is doped higher than the second outer region. Buried layers are formed of the first dopant type in a second concentration under the pad and rail contacts and under the deep oxide.

Abstract: An electrostatic discharge protection device is formed in a substrate and contains a drain area of a first dopant concentration abutting an extended drain area having a dopant concentration lower than the first dopant concentration. Similarly, a highly doped source area abuts a lower doped source extension area. The source and drain are laterally bounded by oxide regions and covered by an insulation layer. The areas of lower doping prevent charge crowding during an electrostatic discharge event by resistively forcing current though the nearly planer bottom surface of the drain, rather than the curved drain extension. In addition, a highly doped buried layer can abut an area of a graded doping level. By adjusting the doping levels of the graded areas and the buried layers, the substrate breakdown voltage is pre-selected.

Abstract: A variable voltage is provided to gates of isolation transistors in DRAM devices between digit lines containing many storage cells and a sense amplifier. The gate of the isolation transistor is provided a voltage pumped higher than the supply voltage during read time to ensure that a small differential voltage on the digit lines is correctly read. A lower voltage is provided at sense time such that the isolation gate provides a higher resistance during sense time. During restore time, the isolation gate voltage is again raised above the operating voltage to minimize the effects of isolation transistor threshold voltage, Vt. In further embodiments, the higher voltage is only provided during restore time and the read and sense voltages are varied between the higher and lower voltage.

Abstract: An electrostatic discharge protection device is formed in a substrate and contains a drain area of a first dopant concentration abutting an extended drain area having a dopant concentration lower than the first dopant concentration. Similarly, a highly doped source area abuts a lower doped source extension area. The source and drain are laterally bounded by oxide regions and covered by an insulation layer. The areas of lower doping prevent charge crowding during an electrostatic discharge event by resistively forcing current though the nearly planer bottom surface of the drain, a rather than the curved drain extension. In addition, a highly doped buried layer can abut an area of a graded doping level. By adjusting the doping levels of the graded areas and the buried layers, the substrate breakdown voltage is pre-selected.

Abstract: A circuit for programming and reading an antifuse includes a bias circuit for applying a positive voltage to a first terminal of the antifuse, and a programming circuit for coupling a second terminal of the antifuse to an external terminal to allow a relatively large negative programming voltage to be applied to the antifuse. Significantly, the programming voltage is coupled to the antifuse over a conductive path that is isolated from any semiconductor device in the integrated circuit. As a result, the programming voltage cannot overstress any semiconductor devices, thereby allowing the magnitude of the programming voltage to be significantly larger that permitted by conventional antifuse circuits. After the antifuse has been programmed, the antifuse circuit is prepared for use by connecting a jumper from the conductive programming path to ground, thereby grounding the second terminal of the antifuse.

Abstract: A method and apparatus for testing of semiconductor memory devices. In one embodiment, a test mode of operation is defined for a memory device. In a normal mode of operation, a row line than addressed memory cell is asserted in response to applied external signals corresponding to the beginning of a write-back phase of a read-modify-write cycle. The row line is deasserted on response to applied external signals corresponding to the end of the write-back phase. In the test mode of operation, the row line is asserted in response to the appropriate applied external signals, but deassertion in response to the appropriate applied external signals is suppressed. Instead, deassertion of the row line is forced only upon expiration of a programmable, predetermined time interval following initiation of the write-back phase. The programmable delay can be established by means of an R-C time constant delay circuit.

Abstract: A variable voltage is provided to gates of isolation transistors in DRAM devices between digit lines containing many storage cells and a sense amplifier. The gate of the isolation transistor is provided a voltage pumped higher than the supply voltage during read time to ensure that a small differential voltage on the digit lines is correctly read. A lower voltage is provided at sense time such that the isolation gate provides a higher resistance during sense time. During restore time, the isolation gate voltage is again raised above the operating voltage to minimize the effects of isolation transistor threshold voltage, Vt. In further embodiments, the higher voltage is only provided during restore time and the read and sense voltages are varied between the higher and lower voltage.

Abstract: An internal voltage regulator for a synchronous random access memory (“SDRAM”) uses a regulator circuit to supply power to charge pumps that is separate from a regulator circuit that supplies power to the arrays of the SDRAM. The regulator supplies an output voltage to the charge pumps that is maintained constant as the external supply voltage is increased beyond its normal operating range. In contrast, a regulated circuit that supplies power to the arrays increases as the supply voltage is increase beyond its normal operating range. As a result, the voltage regulator allows the arrays to be stress tested with a relatively high regulated output voltage without applying an excessive and potentially damaging regulated output voltage to the charge pumps.

Abstract: A method and circuit for rapidly equilibrating paired digit lines of a memory array of a dynamic random access memory device is described. The equilibrate circuit includes a bias-circuit coupled to sense amplifier circuitry for adjusting the equilibrate voltage during testing. A method is described for testing memory cell margin by adjusting the equilibrate voltage until an error is detected. The bias circuit is described as a pull-up transistor coupled to a common mode of a cross-coupled n-sense amplifier.

Abstract: A method and circuit for rapidly equilibrating paired digit lines of a memory array of a dynamic random access memory device is described. The equilibrate circuit includes a bias-circuit coupled to sense amplifier circuitry for adjusting the equilibrate voltage during testing. A method is described for testing memory cell margin by adjusting the equilibrate voltage until an error is detected. The bias circuit is described as a pull-up transistor coupled to a common mode of a cross-coupled n-sense amplifier.

Abstract: An internal voltage regulator for a synchronous random access memory “SDRAM”) uses a regulator circuit to supply power to charge pumps that is separate from a regulator circuit that supplies power to the arrays of the SDRAM. The regulator supplies an output voltage to the charge pumps that is maintained constant as the external supply voltage is increased beyond its normal operating range. In contrast, a regulated circuit that supplies power to the arrays increases as the supply voltage is increase beyond its normal operating range. As a result, the voltage regulator allows the arrays to be stress tested with a relatively high regulated output voltage without applying an excessive and potentially damaging regulated output voltage to the charge pumps.

Abstract: A method and apparatus for testing of semiconductor memory devices. In one embodiment, a test mode of operation is defined for a memory device. In a normal mode of operation, a row line to an addressed memory cell is asserted in response to applied external signals corresponding to the beginning of a write-back phase of a read-modify-write cycle. The row line is deasserted on response to applied external signals corresponding to the end of the write-back phase. In the test mode of operation, the row line is asserted in response to the appropriate applied external signals, but deassertion in response to the appropriate applied external signals is suppressed. Instead, deassertion of the row line is forced only upon expiration of a programmable, predetermined time interval following initiation of the write-back phase. The programmable delay can be established by means of an R-C time constant delay circuit.

Abstract: A circuit is provided to isolate a contact pad from a logic circuit of a die once the contact pad is no longer needed. This circuit can take many forms including a CMOS multiplexer controlled by a fuse or anti-fuse, an NMOS or PMOS pass gate controlled by a fuse or anti-fuse, or even a fusible link which is severed to effect isolation. Additionally, a circuit is provided that switchably isolates one of two contact pads from a logic circuit.

Abstract: A method and circuit for rapidly equilibrating paired digit lines of a memory array of a dynamic random access memory device is described. The equilibrate circuit includes a bias-circuit coupled to sense amplifier circuitry for adjusting the equilibrate voltage during testing. A method is described for testing memory cell margin by adjusting the equilibrate voltage until an error is detected. The bias circuit is described as a pull-up transistor coupled to a common mode of a cross-coupled n-sense amplifier.

Abstract: A variable voltage is provided to gates of isolation transistors in DRAM devices between digit lines containing many storage cells and a sense amplifier. The gate of the isolation transistor is provided a voltage pumped higher than the supply voltage during read time to ensure that a small differential voltage on the digit lines is correctly read. A lower voltage is provided at sense time such that the isolation gate provides a higher resistance during sense time. During restore time, the isolation gate voltage is again raised above the operating voltage to minimize the effects of isolation transistor threshold voltage, Vt. In further embodiments, the higher voltage is only provided during restore time and the read and sense voltages are varied between the higher and lower voltage.

Abstract: The invention is a circuit and method for controlling a high potential at a significant node by controlling the potential at a control input to an electrical device in electrical communication with the significant node. The potential of the control input is controlled by a control circuit. In a first embodiment the control circuit is a potential generator, and in a second embodiment the control circuit is a programmable circuit. The programmable circuit provides a potential at the control input that is directly proportional to a supply potential until a maximum potential is reached at which time the control input is maintained at the maximum potential.

Abstract: The present invention discloses an on chip decoupling capacitor structure having a first decoupling capacitor with one electrode formed in the conductively doped silicon substrate and a second electrode made of conductively doped polysilicon. The second electrode is a common electrode to a second decoupling capacitor overlying and thereby coupled in parallel to said first decoupling capacitor. The second capacitor's first electrode is the common electrode and its second electrode is made of conductively doped polysilicon. The electrodes made of the conductively doped polysilicon may be further enhanced by forming a silicided material, such as tungsten silicide, thereon. The decoupling capacitors' dielectric can be formed from high dielectric constant materials, such as TEOS, oxide, nitride or any combination thereof.

Abstract: A semiconductor memory device includes a plurality of row lines, a plurality of column lines, and a common storage cell plate. The memory device also includes a cell plate generator which produces a reference voltage. The reference voltage is connected to the common storage cell plate. A row decoder connects a row line voltage to selected individual row lines. A stress mode detection circuit receives a row line stress voltage and generates a stress mode signal in response. The row decoder is responsive to the stress mode signal to simultaneously bias all of the row lines to the row line stress voltage. At least one equilibrate circuit is also connected to receive the stress mode signal and is responsive to the stress mode signal to bias the column lines to the reference voltage. The memory device is furthermore responsive to the stress mode signal to ground the reference voltage.

Abstract: The invention is an output driver circuit of a dynamic random access memory (DRAM) wherein the output driver is wired in a push-pull configuration. The push-pull configuration comprises a pull-up portion and a pull-down portion serially connected at an output node. The pull-up portion comprises a an n-channel metal oxide semiconductor (NMOS) transistor having a gate potential determined by a programmable circuit. In the preferred embodiment the programmable circuit provides a potential to the gate node of the NMOS that is directly proportional to the supply potential until a maximum programmed gate potential is reached. The programmable circuit maintains the maximum programmed gate potential for further increases in the supply potential. The pull-down portion comprises a pull-down NMOS transistor interposed between the output node and ground. The pull-down NMOS transistor is controlled by a pull-down signal on the gate node. When actuated the pull-down transistor provides a low logic level at the output node.