Abstract: A DRAM device having improved performance of peripheral circuitry is described. The performance is improved by selectively having MOS transistors with a thinner gate oxide in peripheral circuits having a lower voltage applied to their gate electrodes. The DRAM device will maintain reliability by having MOS transistors with a thicker gate oxide in the memory cells and selected peripheral circuitry that are subjected to a higher voltage at their gate electrodes. Further this invention describes methods of fabricating the DRAM device with selectively placed multiple gate oxide thickness.

Abstract: A DRAM device having improved performance of peripheral circuitry is described. The performance is improved by selectively having MOS transistors with a thinner gate oxide in peripheral circuits having a lower voltage applied to their gate electrodes. The DRAM device will maintain reliability by having MOS transistors with a thicker gate oxide in the memory cells and selected peripheral circuitry that are subjected to a higher voltage at their gate electrodes. Further this invention describes methods of fabricating the DRAM device with selectively placed multiple gate oxide thickness.

Abstract: A DRAM device having improved performance of peripheral circuitry is described. The performance is improved by selectively having MOS transistors with a thinner gate oxide in peripheral circuits having a lower voltage applied to their gate electrodes. The DRAM device will maintain reliability by having MOS transistors with a thicker gate oxide in the memory cells and selected peripheral circuitry that are subjected to a higher voltage at their gate electrodes. Further this invention describes methods of fabricating the DRAM device with selectively placed multiple gate oxide thickness.

Abstract: A method for making a DRAM MOSFET integrated circuit and resulting device having low leakage and long retention time in a semiconductor wafer is described. A pattern of gate dielectric and gate electrode structures is provided over the semiconductor wafer having a first conductivity imparting dopant in the cell array region and the peripheral circuits region of the integrated circuit. The pattern of gate dielectric and gate electrode structures as a mask for ion implantation to form lightly doped regions of a second and opposite conductivity imparting dopant in the semiconductor wafer wherein certain of the lightly doped regions within the cell array region are to be bit line regions and capacitor node regions. A capacitor is formed within the cell array region. An interlevel dielectric insulating layer is formed over the surface of the structure. A highly doped bit line contact is formed to the bit line regions.

Abstract: Lightly Depleted PMOS (LDP) substrate-plate trench-capacitor (SPT) cell Array architecture is disclosed including three types of devices: An enhancement NMOS transistor (ENMOS) which has a n+ poly gate with a positive threshold voltage range, an enhancement PMOS transistor (EPMOS) having a p+ poly gate with a negative threshold voltage range, and a lightly depleted PMOS transistor (LDPMOS) having a p+ poly gate. The LDPMOS is used as the access transistor in the SPT cell with body biased at the power supply voltage VDD, and can also be used in the write drivers. A sense amplifier is included which is a CMOS cross-coupled latch. An n-well is biased at a lower voltage than VDD, such as (VDD--Vg) where Vg is the silicon bandgap, and the lower thresholds enhance faster sensing. The CMOS cross-coupled latch is activated by turning on latching devices.

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: A method of forming a bridge contact between a source diffusion region of a transfer gate FET and a polysilicon-filled trench storage capacitor electrodes of the FET. A layer of titanium is evaporated at a temperature of approximately 370.degree. C., so that the titanium has a substantially columnar grain structure and a minimum of matrix material. The bottom portions of the columnar grains have a lateral length that approximates the lateral length of the dielectric separating the source diffusion from the poly-filled trench. Thus, upon sintering at 700.degree. C. in an N.sub.2 atmosphere, titanium silicide will form over all exposed silicon regions as well as the dielectric, without shorting the FET electrodes together.

Abstract: Two embodiments of a wordline boost clock circuit that can be used in high speed DRAM circuits are disclosed. The clock circuits require only one boost capacitor and discharge the wordlines faster, improving the DRAM access time. The basic feature of the clock circuit is in the floating gate structure of the nmos device which drives the load to negative during the boosting. In the first embodiment of the clock, the gate of a first device is connected to a first node through a second device. A second node, connected to a wordline, is discharged through the first and a third device when a third node is high with a fourth node low. After a sufficient discharge of the second node, the fourth node is pulled to VDD turning the second device on and a fourth device off. The first (NMOS) transistor has its gate and drain connected together and forms a diode.

Abstract: A complementary MOS one-capacitor dynamic RAM cell which operates with a non-boosted wordline without a threshold loss problem and which includes one storage capacitor and n- and p-type transfer devices connected to the storage capacitor which function as two complementary transistor devices having gates controlled by complementary signals on the RAM wordlines.

Abstract: A boost clock signal generator which provides a boost clock signal from a pair of phase clocks. A pair of differentially-connected FET transistors which generate a boost clock signal. The transistors have drain connections connected to each of two clock signals, and commonly connected sources which form an output terminal for the boost clock signal. A series pass FET transistor is connected with each gate of the differential transistors for maintaining the gate at a floating voltage potential. A pair of capacitive elements couple the drain of each pair of differentially-connected FET transistors to the gate of an opposite transistor. A first and second logic circuit are connected to the series pass FET transistors for enabling one or the other of the differnetially-connected FET transistors into conduction.

Abstract: A complementary MOS one-capacitor dynamic RAM cell which operates with a non-boosted wordline without a threshold loss problem and which includes one storage capacitor and n- and p-type transfer devices connected to the storage capacitor which function as two complementary transistor devices having gates controlled by complementary signals on the RAM wordlines.

Abstract: An integrated, self-aligned trench-transistor structure including trench CMOS devices and vertical "strapping transistors" wherein the shallow trench transistors and the strapping trench-transistors are built on top of buried source junctions. A p- epitaxial layer is grown on a substrate and contains an n-well, an n+ source and a p+ source regions. Shallow trenches are disposed in the epitaxial layer and contain n+ polysilicon or metal, such as tungsten, to provide the trench CMOS gates. A gate contact region connects the trenches and the n+ polysilicon or metal in the trenches. The n+ polysilicon or metal in the trenches are isolated by a thin layer of silicon dioxide on the trench walls of the gates. The p+ drain region, along with the filled trench gate element and the p+ source region, form a vertical p-channel (PMOS) trench-transistor. The n+ drain region, along with filled trench gate element and the n+ source form a vertical n-channel (NMOS) transistor.

Abstract: A new high density vertical trench transistor and trench capacitor DRAM (dynamic-random-access memory) cell is described incorporating a wafer with a semiconductor substrate and an epitaxial layer thereon including a vertical transistor disposed in a shallow trench stacked above and self-aligned with a capacitor in a deep trench. The stacked vertical transistor 14 has a channel partly on the horizontal surface and partly along the shallow trench sidewalls. The drain of the access transistor is a lightly-doped drain structure connected to a bitline element. The source of the transistor, located at the bottom of the transistor trench and on top of the center of the trench capacitor, is self-aligned and connected to polysilicon contained inside the trench capacitor. Three sidewalls of the access transistor are surrounded by thick oxide isolation and the remaining one side is connected to drain and bitline contacts.

Abstract: A semiconductor memory cell structure incorporating a vertical access transistor over a trench storage capacitor including a semiconductor wafer having a semiconductor substrate and an epitaxial layer disposed thereon. A relatively deep polysilicon filled trench is disposed in the epitaxial layer and substrate structure, the deep trench having a composite oxide/nitride insulation layer over its vertical and horizontal surfaces to provide a storage capacitor insulator. A relatively shallow trench is disposed in the epitaxial layer over the deep trench region, the shallow trench having an oxide insulation layer on its vertical and horizontal surfaces thereof. A neck structure of epitaxial polysilicon material extends from the top surface of the polysilicon filled deep trench to the bottom surface of the shallow trench.

Abstract: A dynamic random access memory (DRAM) is comprised of a first and a second input/output (I/O) bus, a first and a second I/O sense amplifier, and a first and a second I/O bus precharge circuit. A control circuit is responsive to the state of a mode control signal for enabling the operation of the I/O buses and the precharge circuits such that in one mode of operation the DRAM operates in a conventional single bit per CAS cycle page mode. In a second mode of operation a high speed dual bit per CAS cycle page mode is achieved, wherein the I/O buses are alternately enabled, one being enabled when CAS is asserted and the other being enabled when CAS is deasserted. The dual bit mode of operation provides also for precharging the I/O bus which is not enabled during the period when the other bus is enabled.

Abstract: A fabrication process for providing an epitaxial layer on a silicon substrate and over predefined insulator-capped islands which forms a self-aligned contact window in the epitaxial layer.Application of the method to a three-dimensional dynamic random access memory (DRAM) device structure is shown, with an access transistor formed in monocrystalline silicon stacked on top of a trench capacitor. A fabrication method therefor is shown wherein the contact window for the source-to-trench connection is formed by self-aligned lateral epitaxial growth, followed by a contact-connection formation step using either a second epitaxial growth or a CVD refill and strapping process. The invention can be further applied to other device structures using the described principles, and more specifically to an inverter structure having the driver device stacked over the load-resistor as another example, which can be used as a basic building circuit unit for logic circuits and static-RAM cell.

Abstract: This invention relates generally to Dynamic Random Access Memory (DRAM) cells and more particularly relates to a DRAM cell wherein the storage capacitor of the cell is disposed in a trench formed in a semiconductor substrate. Still more particularly, it relates to a DRAM cell wherein at least a portion of the substrate is heavily doped and forms the counterelectrode of the storage capacitor while a heavily doped polycrystalline plug disposed in the trench capacitor forms the other electrode of the storage capacitor. The DRAM cell includes a field effect access transistor disposed in a well which is opposite in conductivity type to that of the substrate. The well itself is formed in a lightly doped portion of the substrate and may be n or p-type conductivity with the other portions of the cell having conductivity types appropriate for devices fabricated in the CMOS environment.

Abstract: A CMOS boost word-line clock and decoder-driver circuit which can be used for CMOS DRAM's with substrate bias in addition to VDD supply. A boost word-line clock circuit including simple CMOS inverters is used for the word-line boost and the possible voltage overshoot, which usually occurs because of capacitor two-way boost, can be completely eliminated. Also, the circuit can be triggered by a single clock. A high performance decoder circuit is provided in combination with the aforesaid CMOS boost word-line clock circuit, such decoder using NMOS pass-gate in the decoder driver and providing fast word-line boosting. The timing between the decoder and the word-line clock activation is not crucial.

Abstract: Dynamic random access memory (DRAM) devices are taught wherein individual cells, including an access transistor and a storage capacitor are formed on a single-crystal semiconductor chip, and more particularly a three-dimensional dynamic random access memory (DRAM) device structure is described having a single-crystal access transistor stacked on top of a trench capacitor and a fabrication method therefor wherein crystallization seeds are provided by the single-crystal semiconductor area surrounding the cell and/or from the vertical sidewalls of the trench and wherein the access transistor is isolated by insulator. In the structure, a trench is located in a p+ type substrate containing heavily doped N+ polysilicon. A composite film of SiO.sub.2 /Si.sub.3 N.sub.4 /SiO.sub.2 is provided for the capacitor storage insulator. A thin layer of SiO.sub.2 is disposed over the polysilicon. A lightly doped p-type epi silicon layer is located over the substrate and SiO.sub.2 layer.

Abstract: A voltage boosting circuit combination for semiconductor memory word-lines having a charge/discharge circuit including a first pair of MOSFET's and connected to a first clock signal. An output lead is connected from the charge/discharge circuit to a word-line of a semiconductor memory. The first clock signal .PHI.A thereon is connected to the charge/discharge circuit for actuating the MOSFET's to produce a voltage change on the output lead from a first voltage level to a second voltage level. The circuit combination also includes a threshold voltage circuit having a second pair of MOSFET's, which is connected to a second clock signal .PHI.C for controlling the voltage level in the threshold voltage circuit. A lead is provided connecting the threshold voltage circuit to the charge/discharge circuit. The circuit combination further includes an output signal boosting circuit having a third pair of MOSFET's which is connected to a third clock signal .PHI.