Abstract: A semiconductor processing method of forming field isolation oxide relative to a silicon substrate includes, i) rapid thermal nitridizing an exposed silicon substrate surface to form a base silicon nitride layer on the silicon substrate; ii) providing a silicon nitride masking layer over the nitride base layer, the base and masking silicon nitride layers comprising a composite of said layers of a combined thickness effective to restrict appreciable oxidation of silicon substrate thereunder when the substrate is exposed to LOCOS conditions; and iii) exposing the substrate to oxidizing conditions effective to form field isolation oxide on substrate areas not masked by the base and masking silicon nitride layers composite.

Abstract: A method of fabricating a gate having a barrier layer of titanium silicide is comprised of the steps of forming a layer of gate oxide. The gate oxide may be formed using a standard LOCOS process. A layer of doped polysilicon is deposited over the layer of gate oxide. A layer of titanium silicide is formed in a predetermined relationship with respect the layer of doped polysilicon, i.e., it may be deposited on top of the polysilicon or formed in a top surface of the polysilicon layer. A layer of tungsten silicide is deposited on top of the layer of titanium silicide. The layers of gate oxide, doped polysilicon, titanium silicide, and tungsten silicide are etched to form the gate. A gate thus fabricated is also disclosed.

Abstract: A method of fabricating a gate having a barrier layer of titanium silicide is comprised of the steps of forming a layer of gate oxide. The gate oxide may be formed using a standard LOCOS process. A layer of doped polysilicon is deposited over the layer of gate oxide. A layer of titanium silicide is formed in a predetermined relationship with respect the layer of doped polysilicon, i.e., it may be deposited on top of the polysilicon or formed in a top surface of the polysilicon layer. A layer of tungsten silicide is deposited on top of the layer of titanium silicide. The layers of gate oxide, doped polysilicon, titanium silicide, and tungsten silicide are etched to form the gate. A gate thus fabricated is also disclosed.

Abstract: A semiconductor processing method of forming field isolation oxide relative to a silicon substrate includes, i) rapid thermal nitridizing an exposed silicon substrate surface to form a base silicon nitride layer on the silicon substrate; ii) providing a silicon nitride masking layer over the nitride base layer, the base and masking silicon nitride layers comprising a composite of said layers of a combined thickness effective to restrict appreciable oxidation of silicon substrate thereunder when the substrate is exposed to LOCOS conditions; and iii) exposing the substrate to oxidizing conditions effective to form field isolation oxide on substrate areas not masked by the base and masking silicon nitride layers composite.

Abstract: A method of fabricating a gate having a barrier layer of titanium silicide is comprised of the steps of forming a layer of gate oxide. The gate oxide may be formed using a standard LOCOS process. A layer of doped polysilicon is deposited over the layer of gate oxide. A layer of titanium silicide is formed in a predetermined relationship with respect the layer of doped polysilicon, i.e., it may be deposited on top of the polysilicon or formed in a top surface of the polysilicon layer. A layer of tungsten silicide is deposited on top of the layer of titanium silicide. The layers of gate oxide, doped polysilicon, titanium silicide, and tungsten silicide are etched to form the gate. A gate thus fabricated is also disclosed.

Abstract: A LOCOS process is enhanced by enhancing the depth of field oxide in regions having a narrow field oxide width. Subsequent to forming a pattern of nitride to define the field oxide and active area, photoresist is applied to selected areas of the wafer. An impurity is then applied to the underlying semiconductor substrate in areas not protected by photoresist and nitride. The impurity results in an enhanced oxidation rate and therefore compensates for a thinning effect in selected field oxide areas, such as those having a narrow width. Subsequent formation of the field oxide results in the doped material being consumed by the oxide.

Abstract: A polysilicon layer is provided with a p-type impurity, and masked with an oxide mask to define a p-type region of the polysilicon layer. A second impurity is then provided into first unmasked regions of the polysilicon layer. A second oxide mask is deposited and anisotropically etched to form spacers adjacent to the first oxide mask. The spacers define two diffusion barrier regions of the polysilicon layer adjacent to the p-type region. An n-type impurity is then provided into second unmasked regions of the polysilicon layer to form two n-type regions adjacent the diffusion barrier regions. The diffusion barrier regions prevent cross diffusion of the p-type and the n-type impurities within the polysilicon layer, while also being of sufficient dimensions to permit normal p/n operations.

Abstract: An existing stacked capacitor fabrication process is modified to construct a three-dimensional stacked capacitor, referred to as a Stacked I-Cell (SIC). The SIC design defines a capacitor storage cell that in the present invention is used in a DRAM process. The SIC is made up of a polysilicon storage node structure having a I-shaped cross-sectional upper portion with a lower portion extending downward and making contact to an active area via a buried contact. The polysilicon storage node structure is overlaid by polysilicon with a dielectric sandwiched in between to form a completed SIC capacitor. The novel 3-dimensional shaped polysilicon storage node plate having an adjustable I-shaped cross-section, allows substantial capacitor plate surface area of 200% or more to be gained at the storage node over that of a conventional STC.

Abstract: A polysilicon layer is provided with a p-type impurity, and masked with an oxide mask to define a p-type region of the polysilicon layer. A second impurity is then provided into first unmasked regions of the polysilicon layer. A second oxide mask is deposited and anisotropically etched to form spacers adjacent to the first oxide mask. The spacers define two diffusion barrier regions of the polysilicon layer adjacent to the p-type region. An n-type impurity is then provided into second unmasked regions of the polysilicon layer to form two n-type regions adjacent the diffusion barrier regions. The diffusion barrier regions prevent cross diffusion of the p-type and the n-type impurities within the polysilicon layer, while also being of sufficient dimensions to permit normal p/n operations.

Abstract: This invention relates to semiconductor circuit memory storage devices and more particularly to a process to develop three-dimensional stacked capacitor cells using a high dielectric constant material as a storage cell dielectric and a combination of conductively doped polysilicon and metal silicide as the capacitor plates of a storage cell for use in high-density dynamic random access memory (DRAM) arrays. The present invention teaches how to fabricate three-dimensional stacked capacitors by modifying an existing stacked capacitor fabrication process to construct the three-dimensional stacked capacitor cell incorporating a high dielectric constant material as the cell dielectric that will allow denser storage cell fabrication with minimal increases of overall memory array dimensions. A capacitance gain of 3 to 10.times. or more over that of a conventional 3-dimensional storage cell is gained by using a high dielectric constant material as the storage cell dielectric.

Abstract: A polysilicon layer is provided with a p-type impurity, and masked with an oxide mask to define a p-type region of the polysilicon layer. A second impurity is then provided into first unmasked regions of the polysilicon layer. A second oxide mask is deposited and anisotropically etched to form spacers adjacent to the first oxide mask. The spacers define two diffusion barrier regions of the polysilicon layer adjacent to the p-type region. An n-type impurity is then provided into second unmasked regions of the polysilicon layer to form two n-type regions adjacent the diffusion barrier regions. The diffusion barrier regions prevent cross diffusion of the p-type and the n-type impurities within the polysilicon layer, while also being of sufficient dimensions to permit normal p/n operations.

Abstract: A lateral extension stacked capacitor (LESC) using a modified stacked capacitor storage cell fabrication process. The LESC is made up of polysilicon structure, having a spherical ended v-shaped cross-section. The storage node plate of the LESC is overlaid by polysilicon with a dielectric sandwiched in between and connects to an access device's active area via a buried contact. The plate extends to an adjacent storage node but is isolated from the adjacent node by less than the critical resolution dimension of a given lithographic technology. The addition of the polysilicon structure increases storage capability 50% without enlarging the surface area defined for a normal buried digit line stacked capacitor cell.

Abstract: A stacked comb spacer capacitor (SCSC) using a modified stacked capacitor storage cell fabrication process. The SCSC is made up of polysilicon structure, having a spiked v-shaped (or comb-shaped) cross-section, located at a buried contact and extending to an adjacent storage node overlaid by polysilicon with a dielectric sandwiched in between. The creation of the spiked polysilicon structure increases storage capability 50% without enlarging the surface area defined for a normal buried digit line stacked capacitor cell. Removing the dielectric residing under the backside of the storage node cell plate and filling that area with polysilicon increases storage capacity by an additional 50% or more.

Abstract: A method of fabricating a semiconductor wafer comprises providing an electrically conductive area on a semiconductor wafer. Multiple alternating layers of first and second materials are provided atop the wafer. The first and second materials need be selectively etchable relative to one another. The multiple layers are etched and the electrically conductive area upwardly exposed to define exposed edges of the multiple layers projecting upwardly from the electrically conductive area. One of the first or second materials is selectively isotropically etched relative to the other to produce indentations which extend generally laterally into the exposed edges of the multiple layers. A layer of electrically conductive material is applied atop the wafer and electrically conductive area, and fills the exposed edge indentations.

Abstract: An existing stacked capacitor fabrication process is modified to construct a three-dimensional stacked capacitor, referred to as a Stacked H-Cell (SHC). The SHC design defines a capacitor storage cell that in the present invention is used in a DRAM process. The SHC is made up of a polysilicon storage node structure having a H-shaped cross-sectional upper portion with a lower portion extending downward and making contact to an active area via a buried contact. The polysilicon storage node structure is overlaid by polysilicon with a dielectric sandwiched in between to form a completed SHC capacitor. The novel 3-dimensional shaped polysilicon storage node plate having an H-shaped cross-section, allows substantial capacitor plate surface area of 200% or more to be gained at the storage node over that of a conventional STC.

Abstract: A multi-poly spacer, double-plate, stacked capacitor or MDSC using a modified stacked capacitor storage cell fabrication process. The MDSC is made up of a rectangular boxed-shaped polysilicon storage node structure, having multiple poly post residing in a buried contact used to connect the MDSC to an active area. The polysilicon storage node structure is overlaid by polysilicon with a dielectric sandwiched in between to form a completed MDSC. Developing the MDSC from a planarized surface allows the capacitor to be fabricated with only 2 photomask steps. With the 3-dimensional shape and a texturized surface of a polysilicon storage node plate, substantial capacitor plate surface area of 100% or more is gained at the storage node.

Abstract: A double dynamic random access memory (DRAM) cell comprising two vertically stacked access transistors and storage capacitors. A first access transistor is formed on a silicon substrate. A seed contact to the first access transistor is then utilized for growing an intermediate silicon substrate by Confined Lateral Selective Epitaxial Overgrowth (CLSEG). A second access transistor is formed upon the intermediate silicon substrate. A storage capacitor for the first access transistor may be formed as a trench capacitor in the silicon substrate. A storage capacitor for the second access transistor may be stacked on the second access transistor. A common buried bit line connects the two access transistors.

Abstract: A mushroom double stacked capacitor (mushroom cell) using a modified stacked capacitor storage cell fabrication process. The mushroom cell is made up of polysilicon structure, having a mushroom extended V-shaped cross-section. The storage node plate of the mushroom cell is overlaid by polysilicon with a dielectric sandwiched in between and connects to an access device's active area via a buried contact. The plate extends to an adjacent storage node but is isolated from the adjacent node by less than the critical resolution dimension of a given lithographic technology. The shape of the polysilicon structure increases storage capability 200% or more without enlarging the surface area defined for a normal buried digit line stacked capacitor cell.

Abstract: A mushroom double stacked capacitor (mushroom cell) using a modified stacked capacitor storage cell fabrication process. The mushroom cell is made up of polysilicon structure, having a mushroom extended V-shaped cross-section. The storage node plate of the mushroom cell is overlaid by polysilicon with a dielectric sandwiched in between and connects to an access device's active area via a buried contact. The plate extends to an adjacent storage node but is isolated from the adjacent node by less than the critical resolution dimension of a given lithographic technology. The shape of the polysilicon structure increases storage capability 200% or more without enlarging the surface area defined for a normal buried digit line stacked capacitor cell.

Abstract: A low-stress process for creating field isolation regions on a silicon substrate that are fully recessed with respect to active areas. The field isolation regions, which have no bird's beak transition regions at their edges, are created by oxidizing an epitaxially-grown layer of silicon, the edges of which are isolated from active area silicon by a an oxide-backed silicon nitride spacer. Each nitride spacer is contiguous with a horizontal silicon nitride layer segment that protects an active area from oxidation during thermal field oxidation. A modification of the process, which requires the deposition of an additional silicon dioxide layer and a wet etch to remove spacers created from that additional layer, further reduces stress during thermal oxidation of the epitaxially-grown silicon layer by providing a void around the periphery of the epitaxial layer for expansion during the thermal oxidation thereof.