Nanowire structure with selected stack removed for reduced gate resistance and method of fabricating same
AssigneeInternational Business Machines Corporation
InventorsHongmei Li, Junjun Li, Xiaoping Liang, Kai Zhao
Life of this patent
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Abstract
Methods to fabricate a stacked nanowire field effect transistor (FET) with reduced gate resistance are provided. The nanowire stack in the stacked nanowire FET can be provided by first forming a material stack of alternating sacrificial material layers and nanowire material layer. The sacrificial material layers and selected nanowire material layers in the material stack are subsequently removed to increase a vertical distance between two active nanowire material layers.
Claims20
A method of forming a semiconductor structure comprising:
- forming a material stack on a substrate, the material stack comprising, from bottom to top, at least a first nanowire material layer, a second nanowire material layer and a top nanowire material layer that are separated from each other by a respective sacrificial material layer;
- forming a hard mask layer on the top nanowire material layer of the material stack;
- patterning the hard mask layer and the top nanowire material layer to provide a vertical stack of a hard mask layer portion and a top nanowire material layer portion, each of the hard mask layer portion and the top nanowire material layer portion including a fin portion connected at each end to a respective supporting portion;
- forming a sacrificial spacer on each sidewall of the vertical stack;
- removing exposed portions of a sacrificial material layer located beneath the top nanowire material layer portion that are not covered by the sacrificial spacer or the vertical stack to expose portions of the second nanowire material layer;
- removing portions of the second nanowire material layer that are not covered by the supporting portions of the hard mask layer portion;
- removing the sacrificial spacer;
- patterning at least a remaining portion of the sacrificial material layer, the first nanowire material layer and another sacrificial material layer overlying the first nanowire material layer to provide a sacrificial material layer portion, a first nanowire material layer portion and another sacrificial material layer portion, each of the sacrificial material layer portion, the first nanowire material layer portion and the another sacrificial material layer portion including a fin portion connected at each end to a respective supporting portion;
- and
- removing fin portions of the sacrificial martial layer portion and the another sacrificial material layer portion.
The method of claim 3, wherein each of the sacrificial material layers comprises Si and each of the nanowire material layers comprises SiGe.
A method of forming a semiconductor structure comprising:
- forming a material stack on a substrate, the material stack comprising alternating nanowire material layers and sacrificial material layers, wherein at least one nanowire material layer located between an upper nanowire material layer and a lower nanowire material layer has an etch selectivity with respect to each of the upper and lower nanowire material layers;
- patterning the material stack to form a vertical stack of alternating nanowire material layer portions and sacrificial material layer portions, wherein each of the alternating nanowire material layer portions and sacrificial material layer portions comprises a fin portion connected at each end to a respective supporting portion;
- removing the fin portion of the at least one nanowire material layer portion;
- and
- removing the fin portions of the sacrificial material layer portions.
A semiconductor structure comprising:
- a first group of vertically stacked nanowires located in a first device area of a substrate, wherein the nanowires in the first group are vertically spaced from each other by a first vertical distance;
- and
- a second group of vertically stacked nanowires located in a second device area of the substrate, wherein the nanowires in the second group are vertically spaced from each other by a second vertical distance,
- wherein the first vertical distance is more than two times greater than the second vertical distance.
Dependencies are inferred from the claim text.