Abstract: A dual port SRAM is shown which comprises first and second word lines and first and second bit lines. A pair of semiconductor memory devices are cross coupled into a bistable circuit for storing true and complement logic levels and are coupled between common and power supply lines. A first access semiconductor is connected between the first bit line and one semiconductor memory device, and its control electrode is connected to the first word line. A second access semiconductor is connected between the second bit line and another of the semiconductor memory devices, and its control electrode is connected to the second word line. A write circuit is provided for applying write potentials to the first bit and word lines to switch the conduction states of the semiconductor memory devices.

Abstract: A sensing circuit for a dynamic random access memory structure is disclosed having first and second bit lines, one of the bit lines being a reference bit line which is held at a precharge voltage when a sense amplifier in the sensing circuit is latched, the sense amplifier includes first and second nodes and first, second, third and fourth transistor devices, the first and second transistor devices form an N-device cross-coupled pair and the third and fourth transistor devices form a P-device cross-coupled pair. The first node is connected to the first bit line and to the second and fourth transistor devices, and the second node is connected to the first and third transistor devices. A first isolation transistor device is connected to the first bit line and a second isolation transistor device is connected to the second bit line. A first clock signal line is connected to the first isolation transistor device and a second clock signal line is connected to the second isolation transistor device.

Abstract: A voltage regulator is provided for controlling an on-chip voltage generator which produces a boost voltage across a charge reservoir for supply to one input of a plurality of word line drivers in a memory array. The regulator is configured such that the charge reservoir voltage will track the power supply voltage and the difference between the power supply voltage and the charge reservoir voltage will be maintained substantially constant over a predefined power supply range. The voltage regulator includes a bandgap reference generator, a first differential circuit for producing a transition voltage from the reference voltage and the power supply voltage, a first transistor for comparing the power supply voltage with the boost voltage, a second transistor for comparing the transition voltage with the reference voltage and a latching comparator for equating the signal outputs from the first and second transistors so as to define a control signal for the on-chip voltage generator.

Abstract: A sensing circuit for dynamic random access memory is disclosed including a pair of bitlines precharged to a first voltage before sensing. A sense amplifier circuit is provided having one node thereof being connected to an external power supply via a switching means including pulsed sense clocks. Control means is provided and is connected to the switching means for controlling the switching means such that the voltage of the power supply is coupled to the node of the sense amplifier for activation for a predetermined period of time, thereby limiting the swing for the high-going bitline to a second voltage lower than said power supply voltage and higher than the first voltage. The reduced bit-line swings are achieved by means of the pulsed sense clocks and the pulse widths for sense clocks are determined by means of a reference bitlines connected to the control means.

Abstract: A wordline driver circuit for reading the contents of a Dynamic Random Access Memory (DRAM). The circuit is implemented in CMOS and is capable of pulling the wordlines to a negative potential with respect to the substrate, thereby decreasing the access time. An NMOS pull-down transistor channel is implemented as a P-well within an N-well. Applying a negative potential to the source of the pull-down transistor permits the transistor to be switched so that a negative potential is applied to the wordline when the NMOS pull-down transistor is gated into conduction. A PMOS pull-up transistor is serially connected to the NMOS pull-down transistor drain, permitting the wordline to be driven positively.

Abstract: A high density substrate plate DRAM cell memory device and process are described in which a buried well region is formed adjacent to deep trench capacitors such that the substrate region of DRAM transfer FETs can be electrically isolated from other FETs on a semiconductor substrate. The buried region is partially formed by ion implantation and diffusion to intersect the walls of the deep trenches.

Abstract: A folded bitline DRAM cell is described which includes a trench capacitor and a planar-configured access transistor. The access transistor is stacked over the capacitor and has a first terminal connected thereto. The access transistor includes a planar-oriented gate. A first wordline has a minor surface in contact with the gate and a major surface that is oriented orthogonally to the gate. An insulating pedestal is positioned adjacent the gate and a passing wordline is positioned on the pedestal, the passing wordline having a major surface parallel to the first wordline. In another embodiment, the folded bitline DRAM cell includes a vertically oriented access transistor having one terminal formed on the upper extent of a contact to the trench capacitor, to provide optimum electrical connection thereto.

Abstract: An improved latch-up protection circuit is disclosed which prevents damage to a CMOS integrated circuit chip due to transient surges or internal-circuitry initiated latch-ups and which clears any latch-up condition or SCR mode. In each embodiment, the latch-up protection circuit is integrated with an on-chip voltage regulation circuit which provides on-chip power to the internal chip circuitry. A first approach to implementing the latch-up protection circuit is to detect an average current through the power transistor of the voltage regulation circuit over a few microseconds. Should the average current exceed a preset value, then the power transistor is turned off and the power (V.sub.DDI) supplied to the internal chip circuitry is reduced to zero, thereby removing the latch-up condition. In a second approach, the on-chip voltage (V.sub.DDI) supplied to internal chip circuitry is compared with a reference voltage signal representative of the occurrence of a latch-up condition, i.e.

Abstract: A method is disclosed for fabricating a DRAM trench capacitor with multiple-pillars inside the trench for increased surface area.A thin pad oxide of a few tens of nonometers is grown on a silicon substrate. A layer of silicon nitride is deposited and another layer of oxide is then deposited. This provides the ONO stack. Then a layer of polysilicon, a layer of nitride, and a layer of large-grained polysilicon are deposited sequentially. Then, a trench is defined by a lithographic mask and the exposed large-grained polysilicon is etched in CF.sub.4. Since CF.sub.4 etches the polysilicon and nitride 20 at almost the same rates, the topographical features existed in the polysilicon layer is copied to the nitride layer. The nitride layer is partially etched. The RIE etching gas is then changed to a mixture of HBR, SiF.sub.4, Helium, and NF.sub.3 which gives a very directional polysilicon etching with a good selectivity to nitride and a very high selectivity to oxide.

Abstract: A computer system is described which includes a DRAM having a plurality of memory cells arranged in rows and columns. The system includes a row address buffer, and circuitry for generating a row address strobe signal that exhibits both active and inactive levels during each DRAM memory cycle and first and second transitions between those levels. A read-in circuit causes read-in of a row address to the DRAM's row address buffer. A delay circuit is responsive to a delayed lagging transition of a row address strobe signal to provide an extended duration control signal which delays an output from the row address buffer. A reset/precharge circuit is active during both the inactive row address strobe signal and the extended duration control signal to reset and precharge circuits and memory cells in the DRAM.

Abstract: A new interdigitated folded bit line (IFBL) architecture for a future generation high density semiconductor memory design is disclosed. In the architecture, the basic cross-point memory cells are organized orthogonally in rows and columns to form an array matrix. The bit lines run in a row direction while the word lines run in a column direction. Transfer transistors are designed to be shared with the same drain junction and the same bit line contact in order to save area. A choice of at least two described embodiments are provided. In one embodiment, referred to as the offset bit line structure, the bit lines are constructed by using two layers of interconnection lines to connect the interdigitated cells associated to it. By connecting the bit line contacts and with two different interconnecting layers and in an alternating row order, the true and complement bit lines and will run parallel to both sides of the memory array.

Abstract: Novel boosted power supplies are disclosed for an internal, on-chip regulator circuit which includes a differential amplifier coupler to a series regulating element operating as a source follower, and in which a voltage pump circuit is provided to generate a boosted power supply for the differential amplifier. The voltage pump preferably includes a ring oscillator for supplying pulses for the voltage pump. The new on-chip voltage regulators are designed for n-well CMOS technology circuits, and can be applied to BiCMOS as well as n-well CMOS circuits. The new circuits utilize voltage boosting techniques to increase the potential at the gate of the series regulating element operating as a source follower, and also improve the power supply rejection. Furthermore, these circuits preferably use clamping diodes to limit negative voltage swings at the gate of the series regulating element and to improve the settling time of the voltage regulator circuit.

Abstract: A DRAM is described including a plurality of operable storage cells, each cell including a capacitance for storing a charge indicative of data. The charge tends to dissipate below an acceptable level after a predetermined time interval T1 for a majority of the operable cells and for a minority of the operable cells, it dissipates below the acceptable level after a shorter time interval T2. The time between DRAM refresh cycles is adjusted so as to be greater than time interval T2. The DRAM comprises: a plurality of redundant storage cells; a decoder for receiving the address of an operable memory cell and providing a first output if the address indicates one of the operable cells of the minority of cells and a second output if the address indicates one of the operable cells of the majority. A switching circuit is responsive to the first output to enable access of a redundant stoarge cell and to prevent access of the minority storage cell.

Abstract: Output driver circuits which do not require two stacked PMOS pull-up transistors in order to interface a lower on-chip supply voltage with a higher voltage off-chip bus provide a significant savings in chip area for DRAMs. According to a first embodiment, an on-chip pump circuit generates the necessary voltage to interface to the external bus. A second embodiment detects and compares the external bus voltage to the on-chip V.sub.DD during tri-state. The higher voltage between the bus and V.sub.DD is used to control the PMOS pull-up device properly. A third embodiment is a hybrid of the first and second embodiments. The external bus is compared to V.sub.DD as in the second embodiment, but a higher-than-V.sub.DD voltage is generated on-chip as in the first embodiment. This on-chip generated voltage is used to control the PMOS pull-up device instead of the bus voltage when the bus voltage is higher than V.sub.DD.

Abstract: A stacked bit-line architecture utilizing high density cross-point memory arrays forms a DRAM semiconductor memory device. The true and complementary bit-line pairs connected to the respective memory cell arrays are formed in two metal layers, one above the other. A bit-line interconnector region is provided that uses a third interconnection layer together with the first and second layers to transpose the vertical stacking of each pair and to transpose the planar alignment of adjacent bit-line pairs. The DRAM memory cell array has a high density cross-point memory cell architecture that behaves electrically as a folded bit-line array.

Abstract: A wordline driver circuit is shown for a DRAM, the circuit comprising a PMOS transistor structure having one contact coupled to a wordline, a second contact coupled to a negative voltage supply and a gate coupled to a control input, the transistor having an N-well about the gate, first and second contacts. An isolating structure is positioned about the N-well to enable it to be a separately controlled from surrounding N-well structures. Pulse circuits are coupled to the transistor for applying, when activated, a potential that enables the wordline to transition to a more negative potential. A bias circuit is also provided for biasing the N-well at a first potential and a second lower potential, the second lower potential applied when the pulse circuits are activated. As a result, body effects in the PMOS transistor are minimized while at the same time enabling a boost potential to be applied to the wordline.

Abstract: A method is described for fabricating a novel double trench memory structure including a shallow trench access transistor adjacent to a deep trench storage capacitor. The described three-dimensional DRAM cell structure consists of shallow trench access transistors and deep trench storage capacitors in a n-well disposed on a semiconductor substrate. In the fabrication method, the vertical access transistors are built adjacent to the one side of one deep substrate-plate trench storage capacitor. Arrangement of the access transistors and trench storage capacitor are different from that of standard single trench cells. The layout of the double trench cell not only provides the advantages of small size, high packing density, lower soft error rate, and higher noise immunity for storage capacitor, but also leads to better performance and an efficient sensing scheme. The structure may be fabricated for p-channel or n-channel embodiments.

Abstract: A structure and fabrication process for a self-aligned, lightly-doped drain/source n-channel field-effect transistor wherein a trench is formed in a well region in a wafer including an epitaxial layer on a substrate. A first, heavily doped drain region and bit line element is formed around the trench on the surface of the well, and a second, lightly-doped drain region is formed proximate to the first drain region and self-aligned to the trench sidewalls. A source region is located beneath the trench, which is filled with polysilicon, above which is gate and further polysilicon forming a transfer wordline. The well region at the trench sidewalls are doped to control the device threshold level, and the device is thereby also located at a wordline/bitline cross-point.

Abstract: Circuitry for implementing a gate enhanced lateral transistor to provide a circuit having a bipolar current driving capability and an FET channel voltage drop. The circuits provide switching of the lateral transistor by enabling both gate and base connections. The device is merged into an FET providing essentially no voltage drop across the collector-emitter connections permitting the collector to reach a full power supply voltage.

Abstract: A method is described for fabricating a DRAM cell in a monocrystalline substrate wherein the cell includes an FET transistor and a capacitor. The method includes the steps of providing a buried storage capacitor in a trench in the substrate; forming a semiconductor mesa area juxtaposed to the buried storage capacitor; opening a channel to a contact of the storage capacitor; depositing a semiconductor layer over the mesa area and in the opened channel; removing a substantial portion of the conductive layer while leaving at least a connecting portion of the conductive layer deposited in the channel and in communication with the semiconductor mesa; and forming an FET gate structure including a source and drain on the mesa whereby the connecting conductive portion provides a conductive path between the FET and the capacitor.