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AssigneeMicron Technology, Inc.
InventorsCem Basceri, Mark Visokay, Thomas M. Graettinger, Steven D. Cummings
Estimating the term…
An enhanced-surface-area conductive layer compatible with high-dielectric constant materials is created by forming a film or layer having at least two phases, at least one of which is electrically conductive. The film may be formed in any convenient manner, such as by chemical vapor deposition techniques, which may be followed by an anneal to better define and/or crystallize the at least two phases. The film may be formed over an underlying conductive layer. At least one of the at least two phases is selectively removed from the film, such as by an etch process that preferentially etches at least one of the at least two phases so as to leave at least a portion of the electrically conductive phase. Ruthenium and ruthenium oxide, both conductive, may be used for the two or more phases. Iridium and its oxide, rhodium and its oxide, and platinum and platinum-rhodium may also be used. A wet etchant comprising ceric ammonium nitrate and acetic acid may be used. In the case of this etchant and a ruthenium/ruthenium oxide film, the etchant preferentially removes the ruthenium phase, leaving a pitted or “islanded” surface of ruthenium oxide physically and electrically connected by the underlying conductive layer. The remaining pitted or islanded layer, together with the underlying conductive layer, if any, constitutes an enhanced-surface-area conductive layer. The enhanced-surface-area conductive layer may be used to form a plate of a storage capacitor in an integrated circuit, such as in a memory cell of a DRAM or the like.
A method of forming a conductive structure, comprising:
A method of forming a conductive structure, the method comprising:
A method of forming a conductive structure, the method comprising:
A method of forming an enhanced-surface-area conductive structure, the method comprising:
A method of forming an enhanced-surface-area conductive structure, the method comprising:
A method of forming a conductive structure, the method comprising:
A method of forming a conductive structure, the method comprising:
A method of forming a conductive structure, the method comprising:
Dependencies are inferred from the claim text.
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From the US filing history. Foreign family members aren’t listed.
Electrodes: having non-planar surfaces, e.g. formed by texturisation
Capacitors having no potential barriers: having dielectrics comprising perovskite structures
Inorganic electric semiconductor devices
Term ended 28 Oct 2020 (estimated)
This invention relates to semiconductor devices and the fabrication thereof, and particularly to ruthenium-containing conductive layers and the formation and use thereof.
A capacitor generally includes two electrical conductors in close proximity to, but separated from, each other. The two conductors form the “plates” of the capacitor, and may be separated by a dielectric material. When a voltage is applied across the plates of a capacitor, electrical charge accumulates on the plates. If the plates are electrically isolated essentially immediately after a voltage is applied, the accumulated charge may be stored on the plates, thus “storing” the applied voltage difference.
The fabrication of integrated circuits involves the formation of conductive layers for use as various circuit components, including for use as capacitor plates. Memory circuits, such as DRAMs the like, use conductive layers to form the opposing plates of storage cell capacitors.
FIG. 1 is a cross-section of a structure with layers used in an example of a process according to one embodiment of the present invention.
FIG. 2 is a cross-section of the layers of FIG. 1 after separation or crystallization of separate phases within one of the layers.
FIG. 3 is a cross-section of the layers of FIG. 2 after preferential removal of one of the phases.
The present invention allows the creation of a surface-area-enhanced conductive layer that has improved compatibility with high-dielectric-constant (“high-κ”) dielectric materials.
This is achieved by forming a layer of material having at least two phases, at least one of phase of which is a conductive material. The layer may be formed over an underlying conductive layer. The layer may have two or more phases in an as-deposited state. The layer may also be treated in physical and/or chemical environments, after or during deposition, which environments enhance, control, or influence the development of zones of different phases within the layer.
After the layer having at least two phases is formed, at least one of the phases is selectively removed, leaving at least one of the phases of a conductive material behind. The remaining conductive phase or phases form, together with the underlying conductive layer, if any, an enhanced-surface area conductive layer which may be used to form a plate of a storage capacitor in an integrated circuit, such as in a memory cell of a DRAM or the like. If the material chosen to form the enhanced-surface-area conductive layer is relatively resistant to oxidation-induced decreases in conductivity, as with an oxygen-containing conductor such as ruthenium oxide, for example, then the tendency toward silicon dioxide formation may be reduced or eliminated, providing improved compatibility for use with high-dielectric-constant dielectric materials.