Abstract: A nonvolatile memory cell having a contact area between a phase-change material such as a chalcogenide and a heat source which is smaller than photolithographic limits is described. To form this cell, a conductive or semiconductor pillar is exposed at a dielectric surface and recessed by selective etch. A thin, conformal layer of a spacer material is deposited on the dielectric top surface, the pillar top surface, and the sidewalls of the recess, then removed from horizontal surfaces by anistropic etch, leaving a spacer on the sidewalls defining a reduced volume within the recess. The phase change material is deposited within the spacer, having a reduced contact area to the underlying conductive or semiconductor pillar.

Abstract: A method is described to form a nonvolatile memory cell having a contact area between a phase-change material such as a chalcogenide and a heat source which is smaller than photolithographic limits. A conductive or semiconductor pillar is exposed at a dielectric surface and recessed by selective etch. A thin, conformal layer of a spacer material is deposited on the dielectric top surface, the pillar top surface, and the sidewalls of the recess, then removed from horizontal surfaces by anistropic etch, leaving a spacer on the sidewalls defining a reduced volume within the recess. The phase change material is deposited within the spacer, having a reduced contact area to the underlying conductive or semiconductor pillar.

Abstract: An antifuse contains a first silicide layer, a grown silicon oxide antifuse layer on a first surface of the first silicide layer, and a first semiconductor layer having a first surface in contact with the antifuse layer.

Abstract: The surface of a conductive layer such as a conductive nitride, a conductive silicide, a metal, or metal alloy or compound, is exposed to a dopant gas which provides an n-type or p-type dopant. The dopant gas may be included in a plasma. Semiconductor material, such as silicon, germanium, or their alloys, is deposited directly on the surface which has been exposed to the dopant gas. During and subsequent to deposition, dopant atoms diffuse into the deposited semiconductor, forming a thin heavily doped region and making a good ohmic contact between the semiconductor material and the underlying conductive layer.

Abstract: A bottom-gate thin film transistor having a silicide gate is described. This transistor is advantageously formed as SONOS-type nonvolatile memory cell, and methods are described to efficiently and robustly form a monolithic three dimensional memory array of such cells. The fabrication methods described avoid photolithography over topography and difficult stack etches of prior art monolithic three dimensional memory arrays of charge storage devices. The use of a silicide gate rather than a polysilicon gate allows increased capacitance across the gate oxide.

Abstract: A nonvolatile memory cell according to the present invention comprises a bottom conductor, a semiconductor pillar, and a top conductor. The semiconductor pillar comprises a junction diode, including a bottom heavily doped region, a middle intrinsic or lightly doped region, and a top heavily doped region, wherein the conductivity types of the top and bottom heavily doped region are opposite. The junction diode is vertically oriented and is of reduced height, between about 500 angstroms and about 3500 angstroms. A monolithic three dimensional memory array of such cells can be formed comprising multiple memory levels, the levels monolithically formed above one another.

Abstract: The present invention relates to use of selective oxidation to oxidize silicon in the presence of tungsten and/or tungsten nitride in memory cells and memory arrays. This technique is especially useful in monolithic three dimensional memory arrays. In one aspect of the invention, the silicon of a diode-antifuse memory cell is selectively oxidized to repair etch damage and reduce leakage, while exposed tungsten of adjacent conductors and tungsten nitride of a barrier layer are not oxidized. In some embodiments, selective oxidation may be useful for gap fill. In another aspect of the invention, TFT arrays made up of charge storage memory cells comprising a polysilicon/tungsten nitride/tungsten gate can be subjected to selective oxidation to passivate the gate polysilicon and reduce leakage.

Abstract: The invention is a chemically grown oxide layer which prevents dopant diffusion between semiconductor layers. The chemically grown oxide layer may be so thin that it does not form a barrier to electrical conduction, and thus may be formed within active devices such as diodes or bipolar transistors. Such a chemically grown oxide film is advantageously used to prevent dopant diffusion in a vertically oriented polysilicon diode formed in a monolithic three dimensional memory array.

Abstract: A memory device includes at least one diode memory cell. The diode is fabricated in a low resistivity, programmed state.

Abstract: A method of making a nonvolatile memory device includes fabricating a diode in a low resistivity, programmed state without an electrical programming step. The memory device includes at least one memory cell. The memory cell is constituted by the diode and electrically conductive electrodes contacting the diode.

Abstract: When chemical mechanical planarization (CMP) is used to planarize a surface coexposing patterned features and dielectric fill, where patterned features and the fill are formed of materials having very different CMP removal rates or characteristics, the planarized surface may have excessively rough, dishing or recessing may take place, or one or more or the materials may be damaged. In structures in which planarity is important, these problems can be prevented by forming a capping layer on the patterned features, wherein the CMP removal rate of the material forming the capping layer is similar to the CMP removal rate of the dielectric fill.

Abstract: The invention provides for a junction diode including a heavily doped first region having a first conductivity type, a second lightly doped or intrinsic region having a second conductivity type, and a third heavily doped region having a second conductivity type. The junction diode comprises more than one semiconductor or semiconductor alloy. In preferred embodiments, the lightly doped or intrinsic region has a higher proportion of germanium than on or the other or both of the heavily doped regions. In preferred embodiments, the junction diode is vertically oriented, and the top region has a higher proportion of silicon than the other regions.

Abstract: A memory cell is formed of a semiconductor junction diode in series with an antifuse. The cell is programmed by rupture of the antifuse. The semiconductor junction diode comprises silicon, the silicon crystallized in contact with a silicide. The suicide apparently provides a template for crystallization, improving crystallinity and conductivity of the diode, and reducing the programming voltage required to program the cell. It is advantageous to reduce a dielectric layer (such as an oxide, nitride, or oxynitride) intervening between the silicon and the silicon-forming metal during the step of forming the silicide.

Abstract: A bottom-gate thin film transistor having a silicide gate is described. This transistor is advantageously formed as SONOS-type nonvolatile memory cell, and methods are described to efficiently and robustly form a monolithic three dimensional memory array of such cells. The fabrication methods described avoid photolithography over topography and difficult stack etches of prior art monolithic three dimensional memory arrays of charge storage devices. The use of a silicide gate rather than a polysilicon gate allows increased capacitance across the gate oxide.

Abstract: An improved method for fabricating a three dimensional monolithic memory with increased density. The method includes forming conductors preferably comprising tungsten, then filling and planarizing; above the conductors forming semiconductor elements preferably comprising two diode portions and an antifuse, then filling and planarizing; and continuing to form conductors and semiconductor elements in multiple stories of memories. The arrangement of processing steps and the choice of materials decreases aspect ratio of each memory cell, improving the reliability of gap fill and preventing etch undercut.

Abstract: An improved method for fabricating a three dimensional monolithic memory with increased density. The method includes forming conductors preferably comprising tungsten, then filling and planarizing; above the conductors forming semiconductor elements preferably comprising two diode portions and an antifuse, then filling and planarizing; and continuing to form conductors and semiconductor elements in multiple stories of memories. The arrangement of processing steps and the choice of materials decreases aspect ratio of each memory cell, improving the reliability of gap fill and preventing etch undercut.

Abstract: An improved method for fabricating a three dimensional monolithic memory with increased density. The method includes forming conductors preferably comprising tungsten, then filling and planarizing; above the conductors forming semiconductor elements preferably comprising two diode portions and an antifuse, then filling and planarizing; and continuing to form conductors and semiconductor elements in multiple stories of memories. The arrangement of processing steps and the choice of materials decreases aspect ratio of each memory cell, improving the reliability of gap fill and preventing etch undercut.

Abstract: An improved method for fabricating a three dimensional monolithic memory with increased density. The method includes forming conductors preferably comprising tungsten, then filling and planarizing; above the conductors forming semiconductor elements preferably comprising two diode portions and an antifuse, then filling and planarizing; and continuing to form conductors and semiconductor elements in multiple stories of memories. The arrangement of processing steps and the choice of materials decreases aspect ratio of each memory cell, improving the reliability of gap fill and preventing etch undercut.

Abstract: A thin film transistor with a channel less than 100 angstroms thick, preferably less than 80 angstroms thick, preferably less than 60 angstroms thick. The very thin channel reduces variability of threshold voltage from one TFT to the next. This is particularly advantageous for TFT memory arrays. It is possible that an extremely thin channel restricts the size of grains, forcing many small grains to be formed.

Abstract: A method for forming a contact in a three dimensional monolithic memory is disclosed. In a preferred embodiment, the method comprises depositing a conductive layer over and in contact with a plurality of antifuses, wherein said antifuses are part of a story of active devices formed above a substrate; patterning and etching said conductive layer and insulating dielectric to form a contact void; and filling the contact void, wherein the conductive layer does not comprise silicon.