Abstract:
Conventional fabrication of sidewall oxide around an ONO-type memory cell stack usually produces Bird's Beak because prior to the fabrication, there is an exposed sidewall of the ONO-type memory cell stack that exposes side parts of a plurality of material layers respectively composed of different materials. Certain materials in the stack such as silicon nitrides are more difficult to oxidize than other materials in the stack such polysilicon. As a result oxidation does not proceed uniformly along the multi-layered height of the sidewall. The present disclosure shows how radical-based fabrication of sidewall dielectric can help to reduce the Bird's Beak formation. More specifically, it is indicated that short-lived oxidizing agents (e.g., atomic oxygen) are able to better oxidize difficult to oxidize materials such as silicon nitride and the it is indicated that the short-lived oxidizing agents alternatively or additionally do not diffuse as deeply through already oxidized layers of the sidewall such as silicon oxide layers. As a result, a more uniform sidewall dielectric can be fabricated with more uniform breakdown voltages along it height.
Abstract:
Substrate isolation trench (224) are formed in a semiconductor substrate (120). Dopant (e.g. boron) is implanted into the trench sidewalls by ion implantation to suppress the current leakage along the sidewalls. During the ion implantation, the transistor gate dielectric (520) faces the ion stream, but damage to the gate dielectric is annealed in subsequent thermal steps. In some embodiments, the dopant implantation is an angled implant. The implant is performed from the opposite sides of the wafer, and thus from the opposite sides of each active area. Each active area includes a region implanted from one side and a region implanted from the opposite side. The two regions overlap to facilitate threshold voltage adjustment.
Abstract:
In integrated circuit fabrication, an etch is used that has a lateral component. For example, the etch may be isotropic. Before the isotropic etch of a layer (160), another etch of the same layer is performed. This other etch can be anisotropic. This etch attacks a portion (160X2) of the layer adjacent to the feature to be formed by the isotropic etch. That portion is entirely or partially removed by the anisotropic etch. Then the isotropic etch mask (420) is formed to extend beyond the feature over the location of the portion subjected to the anisotropic etch. If that portion was removed entirely, then the isotropic etch mask may completely seal off the feature to be formed on the side of that portion, so the lateral etching will not occur. If that portion was removed only partially, then the lateral undercut will be impeded because the passage to the feature under the isotropic etch mask will be narrowed.
Abstract:
Conventional fabrication of sidewall oxide around an ONO-type memory cell stack usually produces Bird's Beak because prior to the fabrication, there is an exposed sidewall of the ONO-type memory cell stack that exposes side parts of a plurality of material layers respectively composed of different materials. Certain materials in the stack such as silicon nitrides are more difficult to oxidize than other materials in the stack such polysilicon. As a result oxidation does not proceed uniformly along the multi-layered height of the sidewall. The present disclosure shows how radical-based fabrication of sidewall dielectric can help to reduce the Bird's Beak formation. More specifically, it is indicated that short-lived oxidizing agents (e.g., atomic oxygen) are able to better oxidize difficult to oxidize materials such as silicon nitride and the it is indicated that the short-lived oxidizing agents alternatively or additionally do not diffuse as deeply through already oxidized layers of the sidewall such as silicon oxide layers. As a result, a more uniform sidewall dielectric can be fabricated with more uniform breakdown voltages along it height.
Abstract:
Nonvolatile memory wordlines (160) are formed as sidewall spacers on sidewalls of control gate structures (280). Each control gate structure may contain floating and control gates (120, 140), or some other elements. Pedestals (340) are formed adjacent to the control gate structures before the conductive layer (160) for the wordlines is deposited. The pedestals will facilitate formation of the contact openings (330.1) that will be etched in an overlying dielectric (310) to form contacts to the wordlines. The pedestals can be dummy structures. A pedestal can physically contact two wordlines.
Abstract:
In integrated circuit fabrication, an etch is used that has a lateral component. For example, the etch may be isotropic. Before the isotropic etch of a layer (160), another etch of the same layer is performed. This other etch can be anisotropic. This etch attacks a portion (160X2) of the layer adjacent to the feature to be formed by the isotropic etch. That portion is entirely or partially removed by the anisotropic etch. Then the isotropic etch mask (420) is formed to extend beyond the feature over the location of the portion subjected to the anisotropic etch. If that portion was removed entirely, then the isotropic etch mask may completely seal off the feature to be formed on the side of that portion, so the lateral etching will not occur. If that portion was removed only partially, then the lateral undercut will be impeded because the passage to the feature under the isotropic etch mask will be narrowed.
Abstract:
The present invention provides a bipolar transistor located on a semiconductor wafer substrate. The bipolar transistor may comprise a collector located in the semiconductor wafer substrate, a base located in the collector, and an emitter located on the base and in contact with at least a portion of the base, wherein the emitter has a low K layer located therein. The low K layer may be, for example, located proximate a side of the emitter, or it may be located proximate opposing sides of the emitter. In all embodiments, however, the low K layer does not interfere with the proper functioning of the bipolar transistor, and substantially reduces the emitter-base capacitance typically associated with conventional bipolar transistors.
Abstract:
Substrate isolation trench (224) are formed in a semiconductor substrate (120). Dopant (e.g. boron) is implanted into the trench sidewalls by ion implantation to suppress the current leakage along the sidewalls. During the ion implantation, the transistor gate dielectric (520) faces the ion stream, but damage to the gate dielectric is annealed in subsequent thermal steps. In some embodiments, the dopant implantation is an angled implant. The implant is performed from the opposite sides of the wafer, and thus from the opposite sides of each active area. Each active area includes a region implanted from one side and a region implanted from the opposite side. The two regions overlap to facilitate threshold voltage adjustment.
Abstract:
An ONO-type inter-poly insulator is formed by depositing intrinsic silicon on an oxidation stop layer. In one embodiment, the oxidation stop layer is a nitridated top surface of a lower, and conductively-doped, polysilicon layer. In one embodiment, atomic layer deposition (ALD) is used to precisely control the thickness of the deposited, intrinsic silicon. Heat and an oxidizing atmosphere are used to convert the deposited, intrinsic silicon into thermally-grown, silicon dioxide. The oxidation stop layer impedes deeper oxidation. A silicon nitride layer and an additional silicon oxide layer are further deposited to complete the ONO structure before an upper, and conductively-doped, polysilicon layer is formed. In one embodiment, the lower and upper polysilicon layers are patterned to respectively define a floating gate (FG) and a control gate (CG) of an electrically re-programmable memory cell. In an alternative embodiment, after the middle, silicon nitride of the ONO structure is defined, another layer of intrinsic silicon is deposited, by way of for example, ALD. Heat and an oxidizing atmosphere are used to convert the second deposited, intrinsic silicon into thermally-grown, silicon dioxide. An ONO structure with two thermally-grown, and spaced apart, silicon oxide layers is thereby provided.
Abstract:
Substrate isolation trench (224) are formed in a semiconductor substrate (120). Dopant (e.g. boron) is implanted into the trench sidewalls by ion implantation to suppress the current leakage along the sidewalls. During the ion implantation, the transistor gate dielectric (520) faces the ion stream, but damage to the gate dielectric is annealed in subsequent thermal steps. In some embodiments, the dopant implantation is an angled implant. The implant is performed from the opposite sides of the wafer, and thus from the opposite sides of each active area. Each active area includes a region implanted from one side and a region implanted from the opposite side. The two regions overlap to facilitate threshold voltage adjustment.