Texas Instruments Corporation

David J McElroy

Manzur Gill

Sung-Wei Lin

John Frederic Schreck

Sebastiano D'Arrigo

C Rinn Cleavelin

Graham S Tubbs

Brian W Huber

Cetin Kaya

Phat C Truong

G R Rao

Yoichi Miyai

Benjamin H Ashmore, Jr

John Howard MacPeak

Harvey J Stiegler

Eddie Hearl Breashears

Pradeep L Shah

Debra J Dolby

Hideyuki Fukuhara

Timmie M Coffman

Inn K Lee

Wiley Preston Snuggs

Iano D'Arrigo

Charles J Southard

Gerald R Rogers

Buster Ashmore

Circuits for applying a programming voltage and erase voltage to memory cells in a nonvolatile memory device are disclosed. The reverse breakdown of p-n junctions within the memory cells is prevented by providing a clamping p-n junction in the path used to apply the program or erase voltage to the memory cells. The clamping p-n junction will breakdown before the p-n junctions within the memory cells, protecting the memory cells from the adverse effects of a reverse breakdown condition.

Nonvolatile memory device having program and/or erase voltage clamp

A method for fabricating a semiconductor device includes the steps of: forming fuses (40) and conductive pads (46) above a semiconductor substrate (43); depositing a layer of cap oxide (44) over the fuses and the conductive pads; sintering the cap oxide; etching back the layer of cap oxide until the top surface of an insulator (42) over the fuses and the top surfaces of the conductive pads are exposed; performing electrical tests (48) by way of the conductive pads; trimming (50) at least a part of the fuses with a laser beam; depositing a silicon nitride layer (52) overall; depositing a mask coating over the silicon nitride; patterning the mask coating (54) to expose the conductive pads; and etching the mask coating and the silicon nitride layer to expose the conductive pads.

Method for fabricating a semiconductor device with laser programable

An electrically-erasable, electrically-programmable, read-only-memory cell array is formed in pairs at a face of a semiconductor substrate (22). Each memory cell includes a source region (11) and a drain region (12), with a corresponding channel region between. A Fowler-Nordheim tunnel-window (13a) is located over the source line (17) connected to source (11). A floating gate (13) includes a tunnel-window section. A control gate (14) is disposed over the floating gate (13), insulated by an intervening inter-level dielectric (27). The floating gate (13) and the control gate (14) include a channel section (Ch). The channel section (Ch) is used as a self-alignment implant mask for the source (11) and drain (12) regions, such that the channel-junction edges are aligned with the corresponding edges of the channel section (Ch). The memory cell is programmed by hot-carrier injection from the channel to the floating gate (13), and erased by Fowler-Nordheim tunneling from the floating gate (13) through the tunnel window (13a) to the source-line (17 ). The program and erase regions of the cells are physically separate from each other, and the characteristics, including the oxides, of each of those regions may be made optimum independently from each other.

Method of making an EEPROM cell with separate erasing and programming

The drain-to-source voltage and current for programming a selected nonvolatile memory cell 10 are achieved efficiently by pumping the source 11 of a selected cell 11 to a voltage less than the voltage VSS at the reference-voltage terminal of the memory cell array while, at the same time, pumping the drain 12 of the selected cell 10 to a voltage greater than the voltage VCC, which may be 3 V, at the supply-voltage terminal of the memory cell array. The cell substrate W2 is pumped to a voltage close to the voltage of the source 11 and, optionally, below the voltage of the source 11. One or more simple charge-pump circuits convert the output of the voltage supply VCC to a source-drain voltage and current capable of programming the selected nonvolatile cell 10 by hot carrier injection.

Method and circuitry for programming floating-gate memory cell using a

An integrated circuit structure and process relating to a self-aligned window at the recessed junction of two insulating regions formed on the surface of a semiconductor body. The window may include a trench forming an isolation region between doped semiconductor regions, or may include an electrical conductor connected to a doped semiconductor region, or may include an electrical conductor separated from doped semiconductor regions by an electrical insulator. Embodiments include, but are not limited to, a field-effect transistor, a tunnelling area for a floating gate transistor, and an electrical connection to a doped area of the substrate.

Method of producing a self-aligned window at recessed intersection of

A nonvolatile memory has pairs of cells in which each cell includes a control gate, a floating gate and a source/drain diffusion. A first cell in each of the pairs is producible to have one value of floating-gate to diffusion capacitance. A second cell in each of the pairs is producible to have a second value of floating-gate to diffusion capacitance different from the first value. The memory includes a first circuit for applying a first erasing pulse to the control gates and the diffusions of the first cells of the pairs and includes a second circuit for applying a second erasing pulse to the control gates and the diffusions of the second cells of the pairs. The first erasing pulse is adjustable to have a different magnitude than the second erasing pulse in order to narrow the margin of erased threshold voltages and thereby compensate for misalignment.

EEPROM array with narrow margin of voltage thresholds after erase

A wordline-decode system of a nonvolatile memory array is split into three smaller decoding subsystems (a Read-Mode Decode Subsystem, a Program/Erase-Mode Decode Subsystem and a Segment-Select Decoder Subsystem). The segmented array has small bitline capacitance and requires few input connections to each decoding subsystem. The Read-Mode Decoder circuitry and the Program/Erase-Mode Decoder circuitry are separated, allowing the Read-Mode Decoder circuitry to be desired for high speed access and allowing the Program/Erase-Mode Decoder circuitry to be desired for high voltage operation. Buried-bitline segment-select transistors reduce the area required for those transistors. Erasing may be performed after first checking each row of a segment to determine the present of any over-erased cells. Programming may be performed by allowing the common source-column lines of the selected segment to float and by placing preselected voltages on the appropriate wordline and drain-column line.

Segmented, multiple-decoder memory array and method for programming a

A structure and method for improving the sense margin of nonvolatile memories is disclosed. An improvement to the sense margin of nonvolatile memories is accomplished by improving the margin both for 'ones' at low control gate voltage Vcc and for 'zeros' at high control gate voltage Vcc. Improvement in sensing at low control gate voltages Vcc is accomplished by skewing the sense amplifier response characteristics by forming the channel length of the reference memory cell to have a longer channel length than the memory cells of the array.

Skewed reference to improve ones and zeros in EPROM arrays

A method is described for programming an array of EEPROM cells. Programming occurs through a Fowler-Nordheim tunnel window (34) between a source bitline (24) and a floating gate conductor (42) of a selected cell. The voltages applied to the control gate and to the source are selected to differ sufficiently to cause electrons to be drawn through the tunnel window (34) from the source region (24) to the floating gate conductor (42). The non-selected bitlines have a voltage impressed thereon that is of sufficient value to prevent inadvertent programming of cells in the selected row. The non-selected wordlines (48) have a voltage impressed thereon that is of sufficient value to prevent erasing of programmed non-selected cells.

Programming of an electrically-erasable, electrically-programmable,

An electrically-erasable, electrically-programmable ROM or an EEPROM is constructed using a floating-gate transistor with or without a split gate. The floating-gate transistor may have a self-aligned tunnel window of sublithographic dimension positioned on the opposite side of the source from the channel and drain, in a contact-free cell layout, enhancing the ease of manufacture and reducing cell size. In this cell, the bitlines and source/drain regions are buried beneath relatively thick silicon oxide and the floating gate extends over the thick silicon oxide. Programming and erasing are accomplished by causing electrons to tunnel through the oxide in the tunnel window. The tunnel window has a thinner dielectric than the remainder of the oxides under the floating gate to allow Fowler-Nordheim tunneling. Trenches and ditches are used for electrical isolation between individual memory cells, allowing an increase in cell density.

Method of manufacturing an EEPROM with trench-isolated bitlines

An electrically-erasable, electrically-programmable ROM or an EEPROM is constructed using an enhancement transistor merged with a floating-gate transistor, where the floating-gate transistor has a small self-aligned tunnel window positioned on the opposite side of the source from the channel and drain, in a contact-free cell layout, enhancing the ease of manufacture and reducing cell size. In this cell, the bitlines and source/drain regions are buried beneath relatively thick silicon oxide, which allows a favorable ratio of control gate to floating gate capacitance. Programming and erasing are provided by the tunnel window area on the outside of the source (spaced from the channel). The tunnel window has a thinner dielectric than the remainder of the floating gate to allow Fowler-Nordheim tunneling.

Method of making an electrically-erasable, electrically-programmable

According to the invention, an integrated circuit with improved capacitive coupling is provided, and includes a first conductor (20), a second conductor (16), and a third conductor (22). The second conductor (22) and third conductor (16) are disposed adjacent each other, separated by an insulator region (60). The first conductor (20) contacts the third conductor (16) and extends across a portion of the third conductor (22). The first and third conductors are separated by an insulator region (54). A voltage applied to first conductor (20) and the second conductor (16) is capacitively coupled to third conductor (22).

Integrated circuit with improved capacitive coupling

A contact-free floating-gate non-volatile memory cell array and process with silicided NSAG bitlines and with source/drain regions buried beneath relatively thick silicon oxide. The bitlines have a relatively small resistance, eliminating the need for parallel metallic conductors with numerous bitline contacts. The array has relatively small bitline capacitance and may be constructed having relatively small dimensions. Isolation between wordlines and between bitlines is by thick field oxide. Wordlines may be formed from silicided polycrystalline or other material with low resistivity. Coupling of programming and erasing voltages to the floating gate is improved by extending the gates over the thick field oxide and perhaps by using an insulator with relatively high dielectric constant between the control gate and the floating gate. The resulting structure is a dense cross-point array of progammable memory cells.

Cross-point contact-free floating-gate memory array with silicided

According to the invention, an integrated circuit with improved capacitive coupling is provided, and includes a first conductor (20), a second conductor (16), and a third conductor (22). The second conductor (22) and third conductor (16) are disposed adjacent each other, separated by an insulator region (60). The first conductor (20) contacts the third conductor (16) and extends across a portion of the third conductor (22). The first and third conductors are separated by an insulator region (54). A voltage applied to first conductor (20) and second conductor (16) is capacitively coupled to third conductor (22).

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Houston, TX, United States of America

David J McElroy